Lung protective mechanical ventilation and two year survival in patients with acute lung injury: prospective cohort study

PubMed Central

Colantuoni, Elizabeth; Mendez-Tellez, Pedro A; Dinglas, Victor D; Sevransky, Jonathan E; Dennison Himmelfarb, Cheryl R; Desai, Sanjay V; Shanholtz, Carl; Brower, Roy G; Pronovost, Peter J

2012-01-01

Objective To evaluate the association of volume limited and pressure limited (lung protective) mechanical ventilation with two year survival in patients with acute lung injury. Design Prospective cohort study. Setting 13 intensive care units at four hospitals in Baltimore, Maryland, USA. Participants 485 consecutive mechanically ventilated patients with acute lung injury. Main outcome measure Two year survival after onset of acute lung injury. Results 485 patients contributed data for 6240 eligible ventilator settings, as measured twice daily (median of eight eligible ventilator settings per patient; 41% of which adhered to lung protective ventilation). Of these patients, 311 (64%) died within two years. After adjusting for the total duration of ventilation and other relevant covariates, each additional ventilator setting adherent to lung protective ventilation was associated with a 3% decrease in the risk of mortality over two years (hazard ratio 0.97, 95% confidence interval 0.95 to 0.99, P=0.002). Compared with no adherence, the estimated absolute risk reduction in two year mortality for a prototypical patient with 50% adherence to lung protective ventilation was 4.0% (0.8% to 7.2%, P=0.012) and with 100% adherence was 7.8% (1.6% to 14.0%, P=0.011). Conclusions Lung protective mechanical ventilation was associated with a substantial long term survival benefit for patients with acute lung injury. Greater use of lung protective ventilation in routine clinical practice could reduce long term mortality in patients with acute lung injury. Trial registration Clinicaltrials.gov NCT00300248. PMID:22491953

Variable tidal volumes improve lung protective ventilation strategies in experimental lung injury.

PubMed

Spieth, Peter M; Carvalho, Alysson R; Pelosi, Paolo; Hoehn, Catharina; Meissner, Christoph; Kasper, Michael; Hübler, Matthias; von Neindorff, Matthias; Dassow, Constanze; Barrenschee, Martina; Uhlig, Stefan; Koch, Thea; de Abreu, Marcelo Gama

2009-04-15

Noisy ventilation with variable Vt may improve respiratory function in acute lung injury. To determine the impact of noisy ventilation on respiratory function and its biological effects on lung parenchyma compared with conventional protective mechanical ventilation strategies. In a porcine surfactant depletion model of lung injury, we randomly combined noisy ventilation with the ARDS Network protocol or the open lung approach (n = 9 per group). Respiratory mechanics, gas exchange, and distribution of pulmonary blood flow were measured at intervals over a 6-hour period. Postmortem, lung tissue was analyzed to determine histological damage, mechanical stress, and inflammation. We found that, at comparable minute ventilation, noisy ventilation (1) improved arterial oxygenation and reduced mean inspiratory peak airway pressure and elastance of the respiratory system compared with the ARDS Network protocol and the open lung approach, (2) redistributed pulmonary blood flow to caudal zones compared with the ARDS Network protocol and to peripheral ones compared with the open lung approach, (3) reduced histological damage in comparison to both protective ventilation strategies, and (4) did not increase lung inflammation or mechanical stress. Noisy ventilation with variable Vt and fixed respiratory frequency improves respiratory function and reduces histological damage compared with standard protective ventilation strategies.

Numerical simulation of volume-controlled mechanical ventilated respiratory system with 2 different lungs.

PubMed

Shi, Yan; Zhang, Bolun; Cai, Maolin; Zhang, Xiaohua Douglas

2017-09-01

Mechanical ventilation is a key therapy for patients who cannot breathe adequately by themselves, and dynamics of mechanical ventilation system is of great significance for life support of patients. Recently, models of mechanical ventilated respiratory system with 1 lung are used to simulate the respiratory system of patients. However, humans have 2 lungs. When the respiratory characteristics of 2 lungs are different, a single-lung model cannot reflect real respiratory system. In this paper, to illustrate dynamic characteristics of mechanical ventilated respiratory system with 2 different lungs, we propose a mathematical model of mechanical ventilated respiratory system with 2 different lungs and conduct experiments to verify the model. Furthermore, we study the dynamics of mechanical ventilated respiratory system with 2 different lungs. This research study can be used for improving the efficiency and safety of volume-controlled mechanical ventilation system. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of positive end-expiratory pressure and recruitment maneuvers in a ventilator-induced injury mouse model

PubMed Central

Franzi, Lisa M.; Linderholm, Angela L.; Last, Jerold A.; Adams, Jason Y.; Harper, Richart W.

2017-01-01

Background Positive-pressure mechanical ventilation is an essential therapeutic intervention, yet it causes the clinical syndrome known as ventilator-induced lung injury. Various lung protective mechanical ventilation strategies have attempted to reduce or prevent ventilator-induced lung injury but few modalities have proven effective. A model that isolates the contribution of mechanical ventilation on the development of acute lung injury is needed to better understand biologic mechanisms that lead to ventilator-induced lung injury. Objectives To evaluate the effects of positive end-expiratory pressure and recruitment maneuvers in reducing lung injury in a ventilator-induced lung injury murine model in short- and longer-term ventilation. Methods 5–12 week-old female BALB/c mice (n = 85) were anesthetized, placed on mechanical ventilation for either 2 hrs or 4 hrs with either low tidal volume (8 ml/kg) or high tidal volume (15 ml/kg) with or without positive end-expiratory pressure and recruitment maneuvers. Results Alteration of the alveolar-capillary barrier was noted at 2 hrs of high tidal volume ventilation. Standardized histology scores, influx of bronchoalveolar lavage albumin, proinflammatory cytokines, and absolute neutrophils were significantly higher in the high-tidal volume ventilation group at 4 hours of ventilation. Application of positive end-expiratory pressure resulted in significantly decreased standardized histology scores and bronchoalveolar absolute neutrophil counts at low- and high-tidal volume ventilation, respectively. Recruitment maneuvers were essential to maintain pulmonary compliance at both 2 and 4 hrs of ventilation. Conclusions Signs of ventilator-induced lung injury are evident soon after high tidal volume ventilation (as early as 2 hours) and lung injury worsens with longer-term ventilation (4 hrs). Application of positive end-expiratory pressure and recruitment maneuvers are protective against worsening VILI across all time points. Dynamic compliance can be used guide the frequency of recruitment maneuvers to help ameloriate ventilator-induced lung injury. PMID:29112971

Autophagy in pulmonary macrophages mediates lung inflammatory injury via NLRP3 inflammasome activation during mechanical ventilation

PubMed Central

Zhang, Yang; Liu, Gongjian; Dull, Randal O.; Schwartz, David E.

2014-01-01

The inflammatory response is a primary mechanism in the pathogenesis of ventilator-induced lung injury. Autophagy is an essential, homeostatic process by which cells break down their own components. We explored the role of autophagy in the mechanisms of mechanical ventilation-induced lung inflammatory injury. Mice were subjected to low (7 ml/kg) or high (28 ml/kg) tidal volume ventilation for 2 h. Bone marrow-derived macrophages transfected with a scrambled or autophagy-related protein 5 small interfering RNA were administered to alveolar macrophage-depleted mice via a jugular venous cannula 30 min before the start of the ventilation protocol. In some experiments, mice were ventilated in the absence and presence of autophagy inhibitors 3-methyladenine (15 mg/kg ip) or trichostatin A (1 mg/kg ip). Mechanical ventilation with a high tidal volume caused rapid (within minutes) activation of autophagy in the lung. Conventional transmission electron microscopic examination of lung sections showed that mechanical ventilation-induced autophagy activation mainly occurred in lung macrophages. Autophagy activation in the lungs during mechanical ventilation was dramatically attenuated in alveolar macrophage-depleted mice. Selective silencing of autophagy-related protein 5 in lung macrophages abolished mechanical ventilation-induced nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome activation and lung inflammatory injury. Pharmacological inhibition of autophagy also significantly attenuated the inflammatory responses caused by lung hyperinflation. The activation of autophagy in macrophages mediates early lung inflammation during mechanical ventilation via NLRP3 inflammasome signaling. Inhibition of autophagy activation in lung macrophages may therefore provide a novel and promising strategy for the prevention and treatment of ventilator-induced lung injury. PMID:24838752

Bench-to-bedside review: Inhaled nitric oxide therapy in adults

PubMed Central

Creagh-Brown, Benedict C; Griffiths, Mark JD; Evans, Timothy W

2009-01-01

Nitric oxide (NO) is an endogenous mediator of vascular tone and host defence. Inhaled nitric oxide (iNO) results in preferential pulmonary vasodilatation and lowers pulmonary vascular resistance. The route of administration delivers NO selectively to ventilated lung units so that its effect augments that of hypoxic pulmonary vasoconstriction and improves oxygenation. This 'Bench-to-bedside' review focuses on the mechanisms of action of iNO and its clinical applications, with emphasis on acute lung injury and the acute respiratory distress syndrome. Developments in our understanding of the cellular and molecular actions of NO may help to explain the hitherto disappointing results of randomised controlled trials of iNO. PMID:19519946

Lung Structure and the Intrinsic Challenges of Gas Exchange.

PubMed

Hsia, Connie C W; Hyde, Dallas M; Weibel, Ewald R

2016-03-15

Structural and functional complexities of the mammalian lung evolved to meet a unique set of challenges, namely, the provision of efficient delivery of inspired air to all lung units within a confined thoracic space, to build a large gas exchange surface associated with minimal barrier thickness and a microvascular network to accommodate the entire right ventricular cardiac output while withstanding cyclic mechanical stresses that increase several folds from rest to exercise. Intricate regulatory mechanisms at every level ensure that the dynamic capacities of ventilation, perfusion, diffusion, and chemical binding to hemoglobin are commensurate with usual metabolic demands and periodic extreme needs for activity and survival. This article reviews the structural design of mammalian and human lung, its functional challenges, limitations, and potential for adaptation. We discuss (i) the evolutionary origin of alveolar lungs and its advantages and compromises, (ii) structural determinants of alveolar gas exchange, including architecture of conducting bronchovascular trees that converge in gas exchange units, (iii) the challenges of matching ventilation, perfusion, and diffusion and tissue-erythrocyte and thoracopulmonary interactions. The notion of erythrocytes as an integral component of the gas exchanger is emphasized. We further discuss the signals, sources, and limits of structural plasticity of the lung in alveolar hypoxia and following a loss of lung units, and the promise and caveats of interventions aimed at augmenting endogenous adaptive responses. Our objective is to understand how individual components are matched at multiple levels to optimize organ function in the face of physiological demands or pathological constraints. Copyright © 2016 John Wiley & Sons, Inc.

Transport of pulmonary secretions by asymmetric high frequency oscillation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gruenauer, L.M.

1987-01-01

Asymmetric high frequency oscillation (AHFO) was investigated as a mechanism for augmenting the clearance of excess pulmonary secretions from the airways of the lungs. In vitro and in vivo models were developed to test its ability to predictably transport pulmonary secretions. The augmentation of mucus transport by 10 Hz AHFO was investigated in the canine trachea. Ventilation of eight dogs (2 studies each) was performed with three AHFO power settings in random order and conventional mechanical ventilation (CMV) before or after the AHFO trials. Prior to each trial, 35-45 ..mu..l of canine muscus mixed with a radiotagged colloid (/sup 99/Tc/supmore » m/) was instilled in the distal trachea. As the radiotagged mixture traveled up the trachea, tracheal muscus velocities (TMV) were recorded on six channels with a multidetector probe. CMV mean TMVs before and after AHFO were not significantly different. The mean TMV of 6.3 +/- 2.6 mm/min at 30% power AHFO was faster than the CMV mean TVM of 4.1 +/- 2.1 mm/min (p <0.05).« less

One-Lung Ventilation with Additional Ipsilateral Ventilation of Low Tidal Volume and High Frequency in Lung Lobectomy

PubMed Central

Feng, Yong; Wang, Jianyue; Zhang, Yang; Wang, Shiduan

2016-01-01

Background To investigate the protective effects of additional ipsilateral ventilation of low tidal volume and high frequency on lung functions in the patients receiving lobectomy. Material/Methods Sixty patients receiving lung lobectomy were randomized into the conventional one-lung ventilation (CV) group (n=30) and the ipsilateral low tidal volume high frequency ventilation (LV) group (n=30). In the CV group, patients received only contralateral OLV. In the LV group, patients received contralateral ventilation and additional ipsilateral ventilation of low tidal volume of 1–2 ml/kg and high frequency of 40 times/min. Normal lung tissues were biopsied for the analysis of lung injury. Lung injury was scored by evaluating interstitial edema, alveolar edema, neutrophil infiltration, and alveolar congestion. Results At 30 min and 60 min after the initiation of one-lung ventilation and after surgery, patients in the LV group showed significantly higher ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen than those in the CV group (P<0.001). Lung injury was significantly less severe (2.7±0.7) in the LV group than in the CV group (3.1±0.7) (P=0.006). Conclusions Additional ipsilateral ventilation of low tidal volume and high frequency can decrease the risk of hypoxemia and alleviate lung injury in patients receiving lobectomy. PMID:27166086

Aerosol delivery with two ventilation modes during mechanical ventilation: a randomized study.

PubMed

Dugernier, Jonathan; Reychler, Gregory; Wittebole, Xavier; Roeseler, Jean; Depoortere, Virginie; Sottiaux, Thierry; Michotte, Jean-Bernard; Vanbever, Rita; Dugernier, Thierry; Goffette, Pierre; Docquier, Marie-Agnes; Raftopoulos, Christian; Hantson, Philippe; Jamar, François; Laterre, Pierre-François

2016-12-01

Volume-controlled ventilation has been suggested to optimize lung deposition during nebulization although promoting spontaneous ventilation is targeted to avoid ventilator-induced diaphragmatic dysfunction. Comparing topographic aerosol lung deposition during volume-controlled ventilation and spontaneous ventilation in pressure support has never been performed. The aim of this study was to compare lung deposition of a radiolabeled aerosol generated with a vibrating-mesh nebulizer during invasive mechanical ventilation, with two modes: pressure support ventilation and volume-controlled ventilation. Seventeen postoperative neurosurgery patients without pulmonary disease were randomly ventilated in pressure support or volume-controlled ventilation. Diethylenetriaminepentaacetic acid labeled with technetium-99m (2 mCi/3 mL) was administrated using a vibrating-mesh nebulizer (Aerogen Solo(®), provided by Aerogen Ltd, Galway, Ireland) connected to the endotracheal tube. Pulmonary and extrapulmonary particles deposition was analyzed using planar scintigraphy. Lung deposition was 10.5 ± 3.0 and 15.1 ± 5.0 % of the nominal dose during pressure support and volume-controlled ventilation, respectively (p < 0.05). Higher endotracheal tube and tracheal deposition was observed during pressure support ventilation (27.4 ± 6.6 vs. 20.7 ± 6.0 %, p < 0.05). A similar penetration index was observed for the right (p = 0.210) and the left lung (p = 0.211) with both ventilation modes. A high intersubject variability of lung deposition was observed with both modes regarding lung doses, aerosol penetration and distribution between the right and the left lung. In the specific conditions of the study, volume-controlled ventilation was associated with higher lung deposition of nebulized particles as compared to pressure support ventilation. The clinical benefit of this effect warrants further studies. Clinical trial registration NCT01879488.

Predicting the response of the injured lung to the mechanical breath profile

PubMed Central

Smith, Bradford J.; Lundblad, Lennart K. A.; Kollisch-Singule, Michaela; Satalin, Joshua; Nieman, Gary; Habashi, Nader

2015-01-01

Mechanical ventilation is a crucial component of the supportive care provided to patients with acute respiratory distress syndrome. Current practice stipulates the use of a low tidal volume (Vt) of 6 ml/kg ideal body weight, the presumptive notion being that this limits overdistension of the tissues and thus reduces volutrauma. We have recently found, however, that airway pressure release ventilation (APRV) is efficacious at preventing ventilator-induced lung injury, yet APRV has a very different mechanical breath profile compared with conventional low-Vt ventilation. To gain insight into the relative merits of these two ventilation modes, we measured lung mechanics and derecruitability in rats before and following Tween lavage. We fit to these lung mechanics measurements a computational model of the lung that accounts for both the degree of tissue distension of the open lung and the amount of lung derecruitment that takes place as a function of time. Using this model, we predicted how tissue distension, open lung fraction, and intratidal recruitment vary as a function of ventilator settings both for conventional low-Vt ventilation and for APRV. Our predictions indicate that APRV is more effective at recruiting the lung than low-Vt ventilation, but without causing more overdistension of the tissues. On the other hand, low-Vt ventilation generally produces less intratidal recruitment than APRV. Predictions such as these may be useful for deciding on the relative benefits of different ventilation modes and thus may serve as a means for determining how to ventilate a given lung in the least injurious fashion. PMID:25635004

The Society for Translational Medicine: clinical practice guidelines for mechanical ventilation management for patients undergoing lobectomy.

PubMed

Gao, Shugeng; Zhang, Zhongheng; Brunelli, Alessandro; Chen, Chang; Chen, Chun; Chen, Gang; Chen, Haiquan; Chen, Jin-Shing; Cassivi, Stephen; Chai, Ying; Downs, John B; Fang, Wentao; Fu, Xiangning; Garutti, Martínez I; He, Jianxing; He, Jie; Hu, Jian; Huang, Yunchao; Jiang, Gening; Jiang, Hongjing; Jiang, Zhongmin; Li, Danqing; Li, Gaofeng; Li, Hui; Li, Qiang; Li, Xiaofei; Li, Yin; Li, Zhijun; Liu, Chia-Chuan; Liu, Deruo; Liu, Lunxu; Liu, Yongyi; Ma, Haitao; Mao, Weimin; Mao, Yousheng; Mou, Juwei; Ng, Calvin Sze Hang; Petersen, René H; Qiao, Guibin; Rocco, Gaetano; Ruffini, Erico; Tan, Lijie; Tan, Qunyou; Tong, Tang; Wang, Haidong; Wang, Qun; Wang, Ruwen; Wang, Shumin; Xie, Deyao; Xue, Qi; Xue, Tao; Xu, Lin; Xu, Shidong; Xu, Songtao; Yan, Tiansheng; Yu, Fenglei; Yu, Zhentao; Zhang, Chunfang; Zhang, Lanjun; Zhang, Tao; Zhang, Xun; Zhao, Xiaojing; Zhao, Xuewei; Zhi, Xiuyi; Zhou, Qinghua

2017-09-01

Patients undergoing lobectomy are at significantly increased risk of lung injury. One-lung ventilation is the most commonly used technique to maintain ventilation and oxygenation during the operation. It is a challenge to choose an appropriate mechanical ventilation strategy to minimize the lung injury and other adverse clinical outcomes. In order to understand the available evidence, a systematic review was conducted including the following topics: (I) protective ventilation (PV); (II) mode of mechanical ventilation [e.g., volume controlled (VCV) versus pressure controlled (PCV)]; (III) use of therapeutic hypercapnia; (IV) use of alveolar recruitment (open-lung) strategy; (V) pre-and post-operative application of positive end expiratory pressure (PEEP); (VI) Inspired Oxygen concentration; (VII) Non-intubated thoracoscopic lobectomy; and (VIII) adjuvant pharmacologic options. The recommendations of class II are non-intubated thoracoscopic lobectomy may be an alternative to conventional one-lung ventilation in selected patients. The recommendations of class IIa are: (I) Therapeutic hypercapnia to maintain a partial pressure of carbon dioxide at 50-70 mmHg is reasonable for patients undergoing pulmonary lobectomy with one-lung ventilation; (II) PV with a tidal volume of 6 mL/kg and PEEP of 5 cmH 2 O are reasonable methods, based on current evidence; (III) alveolar recruitment [open lung ventilation (OLV)] may be beneficial in patients undergoing lobectomy with one-lung ventilation; (IV) PCV is recommended over VCV for patients undergoing lung resection; (V) pre- and post-operative CPAP can improve short-term oxygenation in patients undergoing lobectomy with one-lung ventilation; (VI) controlled mechanical ventilation with I:E ratio of 1:1 is reasonable in patients undergoing one-lung ventilation; (VII) use of lowest inspired oxygen concentration to maintain satisfactory arterial oxygen saturation is reasonable based on physiologic principles; (VIII) Adjuvant drugs such as nebulized budesonide, intravenous sivelestat and ulinastatin are reasonable and can be used to attenuate inflammatory response.

The Society for Translational Medicine: clinical practice guidelines for mechanical ventilation management for patients undergoing lobectomy

PubMed Central

Zhang, Zhongheng; Brunelli, Alessandro; Chen, Chang; Chen, Chun; Chen, Gang; Chen, Haiquan; Chen, Jin-Shing; Cassivi, Stephen; Chai, Ying; Downs, John B.; Fang, Wentao; Fu, Xiangning; Garutti, Martínez I.; He, Jianxing; Hu, Jian; Huang, Yunchao; Jiang, Gening; Jiang, Hongjing; Jiang, Zhongmin; Li, Danqing; Li, Gaofeng; Li, Hui; Li, Qiang; Li, Xiaofei; Li, Yin; Li, Zhijun; Liu, Chia-Chuan; Liu, Deruo; Liu, Lunxu; Liu, Yongyi; Ma, Haitao; Mao, Weimin; Mao, Yousheng; Mou, Juwei; Ng, Calvin Sze Hang; Petersen, René H.; Qiao, Guibin; Rocco, Gaetano; Ruffini, Erico; Tan, Lijie; Tan, Qunyou; Tong, Tang; Wang, Haidong; Wang, Qun; Wang, Ruwen; Wang, Shumin; Xie, Deyao; Xue, Qi; Xue, Tao; Xu, Lin; Xu, Shidong; Xu, Songtao; Yan, Tiansheng; Yu, Fenglei; Yu, Zhentao; Zhang, Chunfang; Zhang, Lanjun; Zhang, Tao; Zhang, Xun; Zhao, Xiaojing; Zhao, Xuewei; Zhi, Xiuyi; Zhou, Qinghua

2017-01-01

Patients undergoing lobectomy are at significantly increased risk of lung injury. One-lung ventilation is the most commonly used technique to maintain ventilation and oxygenation during the operation. It is a challenge to choose an appropriate mechanical ventilation strategy to minimize the lung injury and other adverse clinical outcomes. In order to understand the available evidence, a systematic review was conducted including the following topics: (I) protective ventilation (PV); (II) mode of mechanical ventilation [e.g., volume controlled (VCV) versus pressure controlled (PCV)]; (III) use of therapeutic hypercapnia; (IV) use of alveolar recruitment (open-lung) strategy; (V) pre-and post-operative application of positive end expiratory pressure (PEEP); (VI) Inspired Oxygen concentration; (VII) Non-intubated thoracoscopic lobectomy; and (VIII) adjuvant pharmacologic options. The recommendations of class II are non-intubated thoracoscopic lobectomy may be an alternative to conventional one-lung ventilation in selected patients. The recommendations of class IIa are: (I) Therapeutic hypercapnia to maintain a partial pressure of carbon dioxide at 50–70 mmHg is reasonable for patients undergoing pulmonary lobectomy with one-lung ventilation; (II) PV with a tidal volume of 6 mL/kg and PEEP of 5 cmH2O are reasonable methods, based on current evidence; (III) alveolar recruitment [open lung ventilation (OLV)] may be beneficial in patients undergoing lobectomy with one-lung ventilation; (IV) PCV is recommended over VCV for patients undergoing lung resection; (V) pre- and post-operative CPAP can improve short-term oxygenation in patients undergoing lobectomy with one-lung ventilation; (VI) controlled mechanical ventilation with I:E ratio of 1:1 is reasonable in patients undergoing one-lung ventilation; (VII) use of lowest inspired oxygen concentration to maintain satisfactory arterial oxygen saturation is reasonable based on physiologic principles; (VIII) Adjuvant drugs such as nebulized budesonide, intravenous sivelestat and ulinastatin are reasonable and can be used to attenuate inflammatory response. PMID:29221302

Comparison of exogenous surfactant therapy, mechanical ventilation with high end-expiratory pressure and partial liquid ventilation in a model of acute lung injury.

PubMed

Hartog, A; Vazquez de Anda, G F; Gommers, D; Kaisers, U; Verbrugge, S J; Schnabel, R; Lachmann, B

1999-01-01

We have compared three treatment strategies, that aim to prevent repetitive alveolar collapse, for their effect on gas exchange, lung mechanics, lung injury, protein transfer into the alveoli and surfactant system, in a model of acute lung injury. In adult rats, the lungs were ventilated mechanically with 100% oxygen and a PEEP of 6 cm H2O, and acute lung injury was induced by repeated lung lavage to obtain a PaO2 value < 13 kPa. Animals were then allocated randomly (n = 12 in each group) to receive exogenous surfactant therapy, ventilation with high PEEP (18 cm H2O), partial liquid ventilation or ventilation with low PEEP (8 cm H2O) (ventilated controls). Blood-gas values were measured hourly. At the end of the 4-h study, in six animals per group, pressure-volume curves were constructed and bronchoalveolar lavage (BAL) was performed, whereas in the remaining animals lung injury was assessed. In the ventilated control group, arterial oxygenation did not improve and protein concentration of BAL and conversion of active to non-active surfactant components increased significantly. In the three treatment groups, PaO2 increased rapidly to > 50 kPa and remained stable over the next 4 h. The protein concentration of BAL fluid increased significantly only in the partial liquid ventilation group. Conversion of active to non-active surfactant components increased significantly in the partial liquid ventilation group and in the group ventilated with high PEEP. In the surfactant group and partial liquid ventilation groups, less lung injury was found compared with the ventilated control group and the group ventilated with high PEEP. We conclude that although all three strategies improved PaO2 to > 50 kPa, the impact on protein transfer into the alveoli, surfactant system and lung injury differed markedly.

Clinical Validation of 4-Dimensional Computed Tomography Ventilation With Pulmonary Function Test Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brennan, Douglas; Schubert, Leah; Diot, Quentin

Purpose: A new form of functional imaging has been proposed in the form of 4-dimensional computed tomography (4DCT) ventilation. Because 4DCTs are acquired as part of routine care for lung cancer patients, calculating ventilation maps from 4DCTs provides spatial lung function information without added dosimetric or monetary cost to the patient. Before 4DCT-ventilation is implemented it needs to be clinically validated. Pulmonary function tests (PFTs) provide a clinically established way of evaluating lung function. The purpose of our work was to perform a clinical validation by comparing 4DCT-ventilation metrics with PFT data. Methods and Materials: Ninety-eight lung cancer patients withmore » pretreatment 4DCT and PFT data were included in the study. Pulmonary function test metrics used to diagnose obstructive lung disease were recorded: forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity. Four-dimensional CT data sets and spatial registration were used to compute 4DCT-ventilation images using a density change–based and a Jacobian-based model. The ventilation maps were reduced to single metrics intended to reflect the degree of ventilation obstruction. Specifically, we computed the coefficient of variation (SD/mean), ventilation V20 (volume of lung ≤20% ventilation), and correlated the ventilation metrics with PFT data. Regression analysis was used to determine whether 4DCT ventilation data could predict for normal versus abnormal lung function using PFT thresholds. Results: Correlation coefficients comparing 4DCT-ventilation with PFT data ranged from 0.63 to 0.72, with the best agreement between FEV1 and coefficient of variation. Four-dimensional CT ventilation metrics were able to significantly delineate between clinically normal versus abnormal PFT results. Conclusions: Validation of 4DCT ventilation with clinically relevant metrics is essential. We demonstrate good global agreement between PFTs and 4DCT-ventilation, indicating that 4DCT-ventilation provides a reliable assessment of lung function. Four-dimensional CT ventilation enables exciting opportunities to assess lung function and create functional avoidance radiation therapy plans. The present work provides supporting evidence for the integration of 4DCT-ventilation into clinical trials.« less

Intermedin Stabilized Endothelial Barrier Function and Attenuated Ventilator-induced Lung Injury in Mice

PubMed Central

Müller-Redetzky, Holger Christian; Kummer, Wolfgang; Pfeil, Uwe; Hellwig, Katharina; Will, Daniel; Paddenberg, Renate; Tabeling, Christoph; Hippenstiel, Stefan; Suttorp, Norbert; Witzenrath, Martin

2012-01-01

Background Even protective ventilation may aggravate or induce lung failure, particularly in preinjured lungs. Thus, new adjuvant pharmacologic strategies are needed to minimize ventilator-induced lung injury (VILI). Intermedin/Adrenomedullin-2 (IMD) stabilized pulmonary endothelial barrier function in vitro. We hypothesized that IMD may attenuate VILI-associated lung permeability in vivo. Methodology/Principal Findings Human pulmonary microvascular endothelial cell (HPMVEC) monolayers were incubated with IMD, and transcellular electrical resistance was measured to quantify endothelial barrier function. Expression and localization of endogenous pulmonary IMD, and its receptor complexes composed of calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMPs) 1–3 were analyzed by qRT-PCR and immunofluorescence in non ventilated mouse lungs and in lungs ventilated for 6 h. In untreated and IMD treated mice, lung permeability, pulmonary leukocyte recruitment and cytokine levels were assessed after mechanical ventilation. Further, the impact of IMD on pulmonary vasoconstriction was investigated in precision cut lung slices (PCLS) and in isolated perfused and ventilated mouse lungs. IMD stabilized endothelial barrier function in HPMVECs. Mechanical ventilation reduced the expression of RAMP3, but not of IMD, CRLR, and RAMP1 and 2. Mechanical ventilation induced lung hyperpermeability, which was ameliorated by IMD treatment. Oxygenation was not improved by IMD, which may be attributed to impaired hypoxic vasoconstriction due to IMD treatment. IMD had minor impact on pulmonary leukocyte recruitment and did not reduce cytokine levels in VILI. Conclusions/Significance IMD may possibly provide a new approach to attenuate VILI. PMID:22563471

Comparison of 4-Dimensional Computed Tomography Ventilation With Nuclear Medicine Ventilation-Perfusion Imaging: A Clinical Validation Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradskiy, Yevgeniy, E-mail: yevgeniy.vinogradskiy@ucdenver.edu; Koo, Phillip J.; Castillo, Richard

Purpose: Four-dimensional computed tomography (4DCT) ventilation imaging provides lung function information for lung cancer patients undergoing radiation therapy. Before 4DCT-ventilation can be implemented clinically it needs to be validated against an established imaging modality. The purpose of this work was to compare 4DCT-ventilation to nuclear medicine ventilation, using clinically relevant global metrics and radiologist observations. Methods and Materials: Fifteen lung cancer patients with 16 sets of 4DCT and nuclear medicine ventilation-perfusion (VQ) images were used for the study. The VQ-ventilation images were acquired in planar mode using Tc-99m-labeled diethylenetriamine-pentaacetic acid aerosol inhalation. 4DCT data, spatial registration, and a density-change-based modelmore » were used to compute a 4DCT-based ventilation map for each patient. The percent ventilation was calculated in each lung and each lung third for both the 4DCT and VQ-ventilation scans. A nuclear medicine radiologist assessed the VQ and 4DCT scans for the presence of ventilation defects. The VQ and 4DCT-based images were compared using regional percent ventilation and radiologist clinical observations. Results: Individual patient examples demonstrate good qualitative agreement between the 4DCT and VQ-ventilation scans. The correlation coefficients were 0.68 and 0.45, using the percent ventilation in each individual lung and lung third, respectively. Using radiologist-noted presence of ventilation defects and receiver operating characteristic analysis, the sensitivity, specificity, and accuracy of the 4DCT-ventilation were 90%, 64%, and 81%, respectively. Conclusions: The current work compared 4DCT with VQ-based ventilation using clinically relevant global metrics and radiologist observations. We found good agreement between the radiologist's assessment of the 4DCT and VQ-ventilation images as well as the percent ventilation in each lung. The agreement lessened when the data were analyzed on a regional level. Our study presents an important step for the integration of 4DCT-ventilation into thoracic clinical practice.« less

Protective lung ventilation in operating room: a systematic review.

PubMed

Futier, E; Constantin, J M; Jaber, S

2014-06-01

Postoperative pulmonary and extrapulmonary complications adversely affect clinical outcomes and healthcare utilization, so that prevention has become a measure of the quality of perioperative care. Mechanical ventilation is an essential support therapy to maintain adequate gas exchange during general anesthesia for surgery. Mechanical ventilation using high tidal volume (VT) (between 10 and 15 mL/kg) has been historically encouraged to prevent hypoxemia and atelectasis formation in anesthetized patients undergoing abdominal and thoracic surgery. However, there is accumulating evidence from both experimental and clinical studies that mechanical ventilation, especially the use of high VT and plateau pressure, may potentially aggravate or even initiate lung injury. Ventilator-associated lung injury can result from cyclic alveolar overdistension of non-dependent lung tissue, and repetitive opening and closing of dependent lung tissue resulting in ultrastructural damage at the junction of closed and open alveoli. Lung-protective ventilation, which refers to the use of lower VT and limited plateau pressure to minimize overdistension, and positive end-expiratory pressure to prevent alveolar collapse at end-expiration, was shown to improve outcome in critically ill patients with acute respiratory distress syndrome (ARDS). It has been recently suggested that this approach might also be beneficial in a broader population, especially in critically ill patients without ARDS at the onset of mechanical ventilation. There is, however, little evidence regarding a potential beneficial effect of lung protective ventilation during surgery, especially in patients with healthy lungs. Although surgical patients are frequently exposed to much shorter periods of mechanical ventilation, this is an important gap in knowledge given the number of patients receiving mechanical ventilation in the operating room. This review developed the benefits of lung protective ventilation during surgery and general anesthesia and offers some recommendations for mechanical ventilation in the surgical context.

Lung-protective ventilation in abdominal surgery.

PubMed

Futier, Emmanuel; Jaber, Samir

2014-08-01

To provide the most recent and relevant clinical evidence regarding the use of prophylactic lung-protective mechanical ventilation in abdominal surgery. Evidence is accumulating, suggesting an association between intraoperative mechanical ventilation strategy and postoperative pulmonary complications in patients undergoing abdominal surgery. Nonprotective ventilator settings, especially high tidal volume (>10-12 ml/kg), very low level of positive end-expiratory pressure (PEEP, <5 cm H2O), or no PEEP, may cause alveolar overdistension and repetitive tidal recruitment leading to ventilator-associated lung injury in patients with healthy lungs. Stimulated by the previous findings in patients with acute respiratory distress syndrome, the use of lower tidal volume ventilation is becoming increasingly more common in the operating room. However, lowering tidal volume, though important, is only part of the overall multifaceted approach of lung-protective mechanical ventilation. Recent data provide compelling evidence that prophylactic lung-protective mechanical ventilation using lower tidal volume (6-8 ml/kg of predicted body weight), moderate PEEP (6-8 cm H2O), and recruitment maneuvers is associated with improved functional or physiological and clinical postoperative outcome in patients undergoing abdominal surgery. The use of prophylactic lung-protective ventilation can help in improving the postoperative outcome.

Variable mechanical ventilation

PubMed Central

Fontela, Paula Caitano; Prestes, Renata Bernardy; Forgiarini Jr., Luiz Alberto; Friedman, Gilberto

2017-01-01

Objective To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Methods Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE®, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". Results A total of 36 studies were selected. Of these, 24 were original studies, including 21 experimental studies and three clinical studies. Conclusion Several experimental studies reported the beneficial effects of distinct variable ventilation strategies on lung function using different models of lung injury and healthy lungs. Variable ventilation seems to be a viable strategy for improving gas exchange and respiratory mechanics and preventing lung injury associated with mechanical ventilation. However, further clinical studies are necessary to assess the potential of variable ventilation strategies for the clinical improvement of patients undergoing mechanical ventilation. PMID:28444076

Towards lung EIT image segmentation: automatic classification of lung tissue state from analysis of EIT monitored recruitment manoeuvres.

PubMed

Grychtol, Bartłomiej; Wolf, Gerhard K; Adler, Andy; Arnold, John H

2010-08-01

There is emerging evidence that the ventilation strategy used in acute lung injury (ALI) makes a significant difference in outcome and that an inappropriate ventilation strategy may produce ventilator-associated lung injury. Most harmful during mechanical ventilation are lung overdistension and lung collapse or atelectasis. Electrical impedance tomography (EIT) as a non-invasive imaging technology may be helpful to identify lung areas at risk. Currently, no automated method is routinely available to identify lung areas that are overdistended, collapsed or ventilated appropriately. We propose a fuzzy logic-based algorithm to analyse EIT images obtained during stepwise changes of mean airway pressures during mechanical ventilation. The algorithm is tested on data from two published studies of stepwise inflation-deflation manoeuvres in an animal model of ALI using conventional and high-frequency oscillatory ventilation. The timing of lung opening and collapsing on segmented images obtained using the algorithm during an inflation-deflation manoeuvre is in agreement with well-known effects of surfactant administration and changes in shunt fraction. While the performance of the algorithm has not been verified against a gold standard, we feel that it presents an important first step in tackling this challenging and important problem.

Potential Role of Lung Ventilation Scintigraphy in the Assessment of COPD

PubMed Central

Cukic, Vesna; Begic, Amela

2014-01-01

Objective: To highlight the importance of the lung ventilation scintigraphy (LVS) to study the regional distribution of lung ventilation and to describe most frequent abnormal patterns of lung ventilation distribution obtained by this technique in COPD and to compare the information obtained by LVS with the that obtained by traditional lung function tests. Material and methods: The research was done in 20 patients with previously diagnosed COPD who were treated in Intensive care unit of Clinic for pulmonary diseases and TB “Podhrastovi” Clinical Center, University of Sarajevo in exacerbation of COPD during first three months of 2014. Each patient was undergone to testing of pulmonary function by body plethysmography and ventilation/perfusion lung scintigraphy with radio pharmaceutics Technegas, 111 MBq Tc -99m-MAA. We compared the results obtained by these two methods. Results: All patients with COPD have a damaged lung function tests examined by body plethysmography implying airflow obstruction, but LVS indicates not only airflow obstruction and reduced ventilation, but also indicates the disorders in distribution in lung ventilation. Conclusion: LVS may add further information to the functional evaluation of COPD to that provided by traditional lung function tests and may contribute to characterizing the different phenotypes of COPD. PMID:25132709

Circuit compliance compensation in lung protective ventilation.

PubMed

Masselli, Grazia Maria Pia; Silvestri, Sergio; Sciuto, Salvatore Andrea; Cappa, Paolo

2006-01-01

Lung protective ventilation utilizes low tidal volumes to ventilate patients with severe lung pathologies. The compensation of breathing circuit effects, i.e. those induced by compressible volume of the circuit, results particularly critical in the calculation of the actual tidal volume delivered to patient's respiratory system which in turns is responsible of the level of permissive hypercapnia. The present work analyzes the applicability of the equation for circuit compressible volume compensation in the case of pressure and volume controlled lung protective ventilation. Experimental tests conducted in-vitro show that the actual tidal volume can be reliably estimated if the compliance of the breathing circuit is measured with the same parameters and ventilation technique that will be utilized in lung protective ventilation. Differences between volume and pressure controlled ventilation are also quantitatively assessed showing that pressure controlled ventilation allows a more reliable compensation of breathing circuit compressible volume.

Transpleural ventilation of explanted human lungs

PubMed Central

Choong, Cliff K; Macklem, Peter T; Pierce, John A; Lefrak, Stephen S; Woods, Jason C; Conradi, Mark S; Yablonskiy, Dimitry A; Hogg, James C; Chino, Kimiaki; Cooper, Joel D

2007-01-01

Background The hypothesis that ventilation of emphysematous lungs would be enhanced by communication with the parenchyma through holes in the pleural surface was tested. Methods Fresh human lungs were obtained from patients with emphysema undergoing lung transplantation. Control human lungs were obtained from organ donors whose lungs, for technical reasons, were not considered suitable for implantation. Lungs were ventilated through the bronchial tree or transpleurally via a small hole communicating with the underlying parenchyma over which a flanged silicone tube had been cemented to the surface of the lung (spiracle). Measurements included flow‐volume‐time curves during passive deflation via each pathway; volume of trapped gas recovered from lungs via spiracles when no additional gas was obtainable passively from the airways; and magnetic resonance imaging assessment of spatial distribution of hyperpolarised helium (3He) administered through either the airways or spiracles. Results In emphysematous lungs, passively expelled volumes at 20 s were 94% greater through spiracles than via the airways. Following passive deflation from the airways, an average of 1.07 litres of trapped gas volume was recoverable via spiracles. Regions were ventilated by spiracles that were less well ventilated via bronchi. Conclusions Because of the extensive collateral ventilation present in emphysematous lungs, direct communication with the lung parenchyma through non‐anatomical pathways has the potential to improve the mechanics of breathing and hence ventilation. PMID:17412776

Intraoperative mechanical ventilation for the pediatric patient.

PubMed

Kneyber, Martin C J

2015-09-01

Invasive mechanical ventilation is required when children undergo general anesthesia for any procedure. It is remarkable that one of the most practiced interventions such as pediatric mechanical ventilation is hardly supported by any scientific evidence but rather based on personal experience and data from adults, especially as ventilation itself is increasingly recognized as a harmful intervention that causes ventilator-induced lung injury. The use of low tidal volume and higher levels of positive end-expiratory pressure became an integral part of lung-protective ventilation following the outcomes of clinical trials in critically ill adults. This approach has been readily adopted in pediatric ventilation. However, a clear association between tidal volume and mortality has not been ascertained in pediatrics. In fact, experimental studies have suggested that young children might be less susceptible to ventilator-induced lung injury. As such, no recommendations on optimal lung-protective ventilation strategy in children with or without lung injury can be made. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanical Ventilation and Bronchopulmonary Dysplasia.

PubMed

Keszler, Martin; Sant'Anna, Guilherme

2015-12-01

Mechanical ventilation is an important potentially modifiable risk factor for the development of bronchopulmonary dysplasia. Effective use of noninvasive respiratory support reduces the risk of lung injury. Lung volume recruitment and avoidance of excessive tidal volume are key elements of lung-protective ventilation strategies. Avoidance of oxidative stress, less invasive methods of surfactant administration, and high-frequency ventilation are also important factors in lung injury prevention. Copyright © 2015 Elsevier Inc. All rights reserved.

Ventilatory Management During Normothermic Ex Vivo Lung Perfusion: Effects on Clinical Outcomes.

PubMed

Terragni, Pier Paolo; Fanelli, Vito; Boffini, Massimo; Filippini, Claudia; Cappello, Paola; Ricci, Davide; Del Sorbo, Lorenzo; Faggiano, Chiara; Brazzi, Luca; Frati, Giacomo; Venuta, Federico; Mascia, Luciana; Rinaldi, Mauro; Ranieri, V Marco

2016-05-01

During ex vivo lung perfusion (EVLP), fixed ventilator settings and monitoring of compliance are used to prevent ventilator-induced lung injury (VILI). Analysis of the airway pressure-time curve (stress index) has been proposed to assess the presence of VILI. We tested whether currently proposed ventilator settings expose lungs to VILI during EVLP and whether the stress index could identify VILI better than compliance. Flow, volume, and airway opening pressure were collected continuously during EVLP. Durations of mechanical ventilation, intensive care unit (ICU) and hospital lengths of stay were recorded in lung recipients. Fourteen lungs underwent EVLP and were transplanted. In 5 lungs, 95 ± 2% of the stress index values were within the 0.95 to 1.05 range (protected); in the remaining nine lungs, 69 ± 1% of the values were greater than 1.05 and 15 ± 3% were less than 0.95 (nonprotected). There was a significant (P < 0.05) increase in cytokine concentrations after 4 hours of EVLP in the nonprotected lungs. Durations of mechanical ventilation, ICU, and hospital lengths of stay were shorter in recipients of protected than that of nonprotected lungs (P < 0.05). There was no correlation between compliance during EVLP and duration of mechanical ventilation or ICU and hospital lengths of stay in recipients, but the stress index during EVLP was significantly correlated with the duration of mechanical ventilation and with ICU and hospital lengths of stay (P < 0.05). This small, preliminary study shows that ventilator settings currently proposed for EVLP may expose lungs to VILI. Use of the stress index to personalize ventilator settings needs to be tested in further clinical studies.

Protective mechanical ventilation does not exacerbate lung function impairment or lung inflammation following influenza A infection.

PubMed

Zosky, Graeme R; Cannizzaro, Vincenzo; Hantos, Zoltan; Sly, Peter D

2009-11-01

The degree to which mechanical ventilation induces ventilator-associated lung injury is dependent on the initial acute lung injury (ALI). Viral-induced ALI is poorly studied, and this study aimed to determine whether ALI induced by a clinically relevant infection is exacerbated by protective mechanical ventilation. Adult female BALB/c mice were inoculated with 10(4.5) plaque-forming units of influenza A/Mem/1/71 in 50 microl of medium or medium alone. This study used a protective ventilation strategy, whereby mice were anesthetized, tracheostomized, and mechanically ventilated for 2 h. Lung mechanics were measured periodically throughout the ventilation period using a modification of the forced oscillation technique to obtain measures of airway resistance and coefficients of tissue damping and tissue elastance. Thoracic gas volume was measured and used to obtain specific airway resistance, tissue damping, and tissue elastance. At the end of the ventilation period, a bronchoalveolar lavage sample was collected to measure inflammatory cells, macrophage inflammatory protein-2, IL-6, TNF-alpha, and protein leak. Influenza infection caused significant increases in inflammatory cells, protein leak, and deterioration in lung mechanics that were not exacerbated by mechanical ventilation, in contrast to previous studies using bacterial and mouse-specific viral infection. This study highlighted the importance of type and severity of lung injury in determining outcome following mechanical ventilation.

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery: study protocol for a randomized controlled trial.

PubMed

Spieth, Peter M; Güldner, Andreas; Uhlig, Christopher; Bluth, Thomas; Kiss, Thomas; Schultz, Marcus J; Pelosi, Paolo; Koch, Thea; Gama de Abreu, Marcelo

2014-05-02

General anesthesia usually requires mechanical ventilation, which is traditionally accomplished with constant tidal volumes in volume- or pressure-controlled modes. Experimental studies suggest that the use of variable tidal volumes (variable ventilation) recruits lung tissue, improves pulmonary function and reduces systemic inflammatory response. However, it is currently not known whether patients undergoing open abdominal surgery might benefit from intraoperative variable ventilation. The PROtective VARiable ventilation trial ('PROVAR') is a single center, randomized controlled trial enrolling 50 patients who are planning for open abdominal surgery expected to last longer than 3 hours. PROVAR compares conventional (non-variable) lung protective ventilation (CV) with variable lung protective ventilation (VV) regarding pulmonary function and inflammatory response. The primary endpoint of the study is the forced vital capacity on the first postoperative day. Secondary endpoints include further lung function tests, plasma cytokine levels, spatial distribution of ventilation assessed by means of electrical impedance tomography and postoperative pulmonary complications. We hypothesize that VV improves lung function and reduces systemic inflammatory response compared to CV in patients receiving mechanical ventilation during general anesthesia for open abdominal surgery longer than 3 hours. PROVAR is the first randomized controlled trial aiming at intra- and postoperative effects of VV on lung function. This study may help to define the role of VV during general anesthesia requiring mechanical ventilation. Clinicaltrials.gov NCT01683578 (registered on September 3 3012).

SU-C-BRA-06: Developing Clinical and Quantitative Guidelines for a 4DCT-Ventilation Functional Avoidance Clinical Trial

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradskiy, Y; Waxweiler, T; Diot, Q

Purpose: 4DCT-ventilation is an exciting new imaging modality that uses 4DCTs to calculate lung ventilation. Because 4DCTs are acquired as part of routine care, calculating 4DCT-ventilation allows for lung function evaluation without additional cost or inconvenience to the patient. Development of a clinical trial is underway at our institution to use 4DCT-ventilation for thoracic functional avoidance with the idea that preferential sparing of functional lung regions can decrease pulmonary toxicity. The purpose of our work was to develop the practical aspects of a 4DCT-ventilation functional avoidance clinical trial including: 1.assessing patient eligibility 2.developing trial inclusion criteria and 3.developing treatment planningmore » and dose-function evaluation strategies. Methods: 96 stage III lung cancer patients from 2 institutions were retrospectively reviewed. 4DCT-ventilation maps were calculated using the patient’s 4DCTs, deformable image registrations, and a density-change-based algorithm. To assess patient eligibility and develop trial inclusion criteria we used an observer-based binary end point noting the presence or absence of a ventilation defect and developed an algorithm based on the percent ventilation in each lung third. Functional avoidance planning integrating 4DCT-ventilation was performed using rapid-arc and compared to the patient’s clinically used plan. Results: Investigator-determined clinical ventilation defects were present in 69% of patients. Our regional/lung-thirds ventilation algorithm identified that 59% of patients have lung functional profiles suitable for functional avoidance. Compared to the clinical plan, functional avoidance planning was able to reduce the mean dose to functional lung by 2 Gy while delivering comparable target coverage and cord/heart doses. Conclusions: 4DCT-ventilation functional avoidance clinical trials have great potential to reduce toxicity, and our data suggest that 59% of lung cancer patients have lung function profiles suitable for functional avoidance. Our study used a retrospective evaluation of a large lung cancer patient database to develop the practical aspects of a 4DCT-ventilation functional avoidance clinical trial. (R.C., E.C., T.G.), NIH Research Scientist Development Award K01-CA181292 (R.C.), and State of Colorado Advanced Industries Accelerator Grant (Y.V.)« less

Intra-operative protective mechanical ventilation in lung transplantation: a randomised, controlled trial.

PubMed

Verbeek, G L; Myles, P S; Westall, G P; Lin, E; Hastings, S L; Marasco, S F; Jaffar, J; Meehan, A C

2017-08-01

Primary graft dysfunction occurs in up to 25% of patients after lung transplantation. Contributing factors include ventilator-induced lung injury, cardiopulmonary bypass, ischaemia-reperfusion injury and excessive fluid administration. We evaluated the feasibility, safety and efficacy of an open-lung protective ventilation strategy aimed at reducing ventilator-induced lung injury. We enrolled adult patients scheduled to undergo bilateral sequential lung transplantation, and randomly assigned them to either a control group (volume-controlled ventilation with 5 cmH 2 O, positive end-expiratory pressure, low tidal volumes (two-lung ventilation 6 ml.kg -1 , one-lung ventilation 4 ml.kg -1 )) or an alveolar recruitment group (regular step-wise positive end-expiratory pressure-based alveolar recruitment manoeuvres, pressure-controlled ventilation set at 16 cmH 2 O with 10 cmH 2 O positive end-expiratory pressure). Ventilation strategies were commenced from reperfusion of the first lung allograft and continued for the duration of surgery. Regular PaO 2 /F I O 2 ratios were calculated and venous blood samples collected for inflammatory marker evaluation during the procedure and for the first 24 h of intensive care stay. The primary end-point was the PaO 2 /F I O 2 ratio at 24 h after first lung reperfusion. Thirty adult patients were studied. The primary outcome was not different between groups (mean (SD) PaO 2 /F I O 2 ratio control group 340 (111) vs. alveolar recruitment group 404 (153); adjusted p = 0.26). Patients in the control group had poorer mean (SD) PaO 2 /F I O 2 ratios at the end of the surgical procedure and a longer median (IQR [range]) time to tracheal extubation compared with the alveolar recruitment group (308 (144) vs. 402 (154) (p = 0.03) and 18 (10-27 [5-468]) h vs. 15 (11-36 [5-115]) h (p = 0.01), respectively). An open-lung protective ventilation strategy during surgery for lung transplantation is feasible, safe and achieves favourable ventilation parameters. © 2017 The Association of Anaesthetists of Great Britain and Ireland.

TU-A-12A-02: Novel Lung Ventilation Imaging with Single Energy CT After Single Inhalation of Xenon: Comparison with SPECT Ventilation Images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Negahdar, M; Yamamoto, T; Shultz, D

Purpose: We propose a novel lung functional imaging method to determine the spatial distribution of xenon (Xe) gas in a single inhalation as a measure of regional ventilation. We compare Xe-CT ventilation to single-photon emission CT (SPECT) ventilation, which is the current clinical reference. Regional lung ventilation information may be useful for the diagnosis and monitoring of pulmonary diseases such as COPD, radiotherapy planning, and assessing the progression of toxicity after radiation therapy. Methods: In an IRB-approved clinical study, Xe-CT and SPECT ventilation scans were acquired for three patients including one patient with severe emphysema and two lung cancer patientsmore » treated with radiotherapy. For Xe- CT, we acquired two breath-hold single energy CT images of the entire lung with inspiration of 100% O2 and a mixture of 70% Xe and 30% O2, respectively. A video biofeedback system was used to achieve reproducible breath-holds. We used deformable image registration to align the breathhold images with each other to accurately subtract them, producing a map of the distribution of Xe as a surrogate of lung ventilation. We divided each lung into twelve parts and correlated the Hounsfield unit (HU) enhancement at each part with the SPECT ventilation count of the corresponding part of the lung. Results: The mean of the Pearson linear correlation coefficient values between the Xe-CT and ventilation SPECT count for all three patients were 0.62 (p<0.01). The Xe-CT image had a higher resolution than SPECT, and did not show central airway deposition artifacts that were present in the SPECT image. Conclusion: We developed a rapid, safe, clinically practical, and potentially widely accessible method for regional lung functional imaging. We demonstrated strong correlations between the Xe-CT ventilation image and SPECT ventilation image as the clinical reference. This ongoing study will investigate more patients to confirm this finding.« less

Simvastatin attenuates neutrophil recruitment in one-lung ventilation model in rats.

PubMed

Leite, Camila Ferreira; Marangoni, Fábio André; Camargo, Enilton Aparecido; Braga, Angélica de Fátima de Assunção; Toro, Ivan Felizardo Contrera; Antunes, Edson; Landucci, Elen Cristina Tiezem; Mussi, Ricardo Kalaf

2013-04-01

To investigate the anti-inflammatory effects of simvastatin in rats undergoing one-lung ventilation (OLV) followed by lung re-expansion. Male Wistar rats (n=30) were submitted to 1-h OLV followed by 1-h lung re-expansion. Treated group received simvastatin (40 mg/kg for 21 days) previous to OLV protocol. Control group received no treatment or surgical/ventilation interventions. Measurements of pulmonary myeloperoxidase (MPO) activity, pulmonary protein extravasation, and serum levels of cytokines and C-reactive protein (CRP) were performed. OLV significantly increased the MPO activity in the collapsed and continuously ventilated lungs (31% and 52% increase, respectively) compared with control (p<0.05). Treatment with simvastatin significantly reduced the MPO activity in the continuously ventilated lung but had no effect on lung edema after OLV. The serum IL-6 and CRP levels were markedly higher in OLV group, but simvastatin treatment failed to affect the production of these inflammatory markers. Serum levels of IL-1β, TNF-α and IL-10 remained below the detection limit in all groups. In an experimental one-lung ventilation model pre-operative treatment with simvastatin reduces remote neutrophil infiltration in the continuously ventilated lung. Our findings suggest that simvastatin may be of therapeutic value in OLV-induced pulmonary inflammation deserving clinical investigations.

Comparison of lung protective ventilation strategies in a rabbit model of acute lung injury.

PubMed

Rotta, A T; Gunnarsson, B; Fuhrman, B P; Hernan, L J; Steinhorn, D M

2001-11-01

To determine the impact of different protective and nonprotective mechanical ventilation strategies on the degree of pulmonary inflammation, oxidative damage, and hemodynamic stability in a saline lavage model of acute lung injury. A prospective, randomized, controlled, in vivo animal laboratory study. Animal research facility of a health sciences university. Forty-six New Zealand White rabbits. Mature rabbits were instrumented with a tracheostomy and vascular catheters. Lavage-injured rabbits were randomized to receive conventional ventilation with either a) low peak end-expiratory pressure (PEEP; tidal volume of 10 mL/kg, PEEP of 2 cm H2O); b) high PEEP (tidal volume of 10 mL/kg, PEEP of 10 cm H2O); c) low tidal volume with PEEP above Pflex (open lung strategy, tidal volume of 6 mL/kg, PEEP set 2 cm H2O > Pflex); or d) high-frequency oscillatory ventilation. Animals were ventilated for 4 hrs. Lung lavage fluid and tissue samples were obtained immediately after animals were killed. Lung lavage fluid was assayed for measurements of total protein, elastase activity, tumor necrosis factor-alpha, and malondialdehyde. Lung tissue homogenates were assayed for measurements of myeloperoxidase activity and malondialdehyde. The need for inotropic support was recorded. Animals that received a lung protective strategy (open lung or high-frequency oscillatory ventilation) exhibited more favorable oxygenation and lung mechanics compared with the low PEEP and high PEEP groups. Animals ventilated by a lung protective strategy also showed attenuation of inflammation (reduced tracheal fluid protein, tracheal fluid elastase, tracheal fluid tumor necrosis factor-alpha, and pulmonary leukostasis). Animals treated with high-frequency oscillatory ventilation had attenuated oxidative injury to the lung and greater hemodynamic stability compared with the other experimental groups. Both lung protective strategies were associated with improved oxygenation, attenuated inflammation, and decreased lung damage. However, in this small-animal model of acute lung injury, an open lung strategy with deliberate hypercapnia was associated with significant hemodynamic instability.

Adaptive support ventilation may deliver unwanted respiratory rate-tidal volume combinations in patients with acute lung injury ventilated according to an open lung concept.

PubMed

Dongelmans, Dave A; Paulus, Frederique; Veelo, Denise P; Binnekade, Jan M; Vroom, Margreeth B; Schultz, Marcus J

2011-05-01

With adaptive support ventilation, respiratory rate and tidal volume (V(T)) are a function of the Otis least work of breathing formula. We hypothesized that adaptive support ventilation in an open lung ventilator strategy would deliver higher V(T)s to patients with acute lung injury. Patients with acute lung injury were ventilated according to a local guideline advising the use of lower V(T) (6-8 ml/kg predicted body weight), high concentrations of positive end-expiratory pressure, and recruitment maneuvers. Ventilation parameters were recorded when the ventilator was switched to adaptive support ventilation, and after recruitment maneuvers. If V(T) increased more than 8 ml/kg predicted body weight, airway pressure was limited to correct for the rise of V(T). Ten patients with a mean (±SD) Pao(2)/Fio(2) of 171 ± 86 mmHg were included. After a switch from pressure-controlled ventilation to adaptive support ventilation, respiratory rate declined (from 31 ± 5 to 21 ± 6 breaths/min; difference = 10 breaths/min, 95% CI 3-17 breaths/min, P = 0.008) and V(T) increased (from 6.5 ± 0.8 to 9.0 ± 1.6 ml/kg predicted body weight; difference = 2.5 ml, 95% CI 0.4-4.6 ml/kg predicted body weight, P = 0.02). Pressure limitation corrected for the rise of V(T), but minute ventilation declined, forcing the user to switch back to pressure-controlled ventilation. Adaptive support ventilation, compared with pressure-controlled ventilation in an open lung strategy setting, delivers a lower respiratory rate-higher V(T) combination. Pressure limitation does correct for the rise of V(T), but leads to a decline in minute ventilation.

Spontaneous breathing during lung-protective ventilation in an experimental acute lung injury model: high transpulmonary pressure associated with strong spontaneous breathing effort may worsen lung injury.

PubMed

Yoshida, Takeshi; Uchiyama, Akinori; Matsuura, Nariaki; Mashimo, Takashi; Fujino, Yuji

2012-05-01

We investigated whether potentially injurious transpulmonary pressure could be generated by strong spontaneous breathing and exacerbate lung injury even when plateau pressure is limited to <30 cm H2O. Prospective, randomized, animal study. University animal research laboratory. Thirty-two New Zealand White rabbits. Lavage-injured rabbits were randomly allocated to four groups to receive low or moderate tidal volume ventilation, each combined with weak or strong spontaneous breathing effort. Inspiratory pressure for low tidal volume ventilation was set at 10 cm H2O and tidal volume at 6 mL/kg. For moderate tidal volume ventilation, the values were 20 cm H2O and 7-9 mL/kg. The groups were: low tidal volume ventilation+spontaneous breathingweak, low tidal volume ventilation+spontaneous breathingstrong, moderate tidal volume ventilation+spontaneous breathingweak, and moderate tidal volume ventilation+spontaneous breathingstrong. Each group had the same settings for positive end-expiratory pressure of 8 cm H2O. Respiratory variables were measured every 60 mins. Distribution of lung aeration and alveolar collapse were histologically evaluated. Low tidal volume ventilation+spontaneous breathingstrong showed the most favorable oxygenation and compliance of respiratory system, and the best lung aeration. By contrast, in moderate tidal volume ventilation+spontaneous breathingstrong, the greatest atelectasis with numerous neutrophils was observed. While we applied settings to maintain plateau pressure at <30 cm H2O in all groups, in moderate tidal volume ventilation+spontaneous breathingstrong, transpulmonary pressure rose >33 cm H2O. Both minute ventilation and respiratory rate were higher in the strong spontaneous breathing groups. Even when plateau pressure is limited to <30 cm H2O, combined with increased respiratory rate and tidal volume, high transpulmonary pressure generated by strong spontaneous breathing effort can worsen lung injury. When spontaneous breathing is preserved during mechanical ventilation, transpulmonary pressure and tidal volume should be strictly controlled to prevent further lung injury.

Histochemical alterations in one lung ventilation.

PubMed

Yin, Kingsley; Gribbin, Elizabeth; Emanuel, Steven; Orndorff, Rebecca; Walker, Jean; Weese, James; Fallahnejad, Manucher

2007-01-01

One lung ventilation is a commonly performed surgical procedure. Although there have been several reports showing that one-lung ventilation can cause pathophysiological alterations such as pulmonary hypoxic vasoconstriction and intrapulmonary shunting, there have been virtually no reports on the effects of one-lung ventilation on lung histology. Yorkshire pigs (11-17 kg) were anesthetized, a tracheotomy performed and a tracheal tube inserted. The chest was opened and one lung ventilation (OLV), was induced by clamping of the right main bronchus. OLV was continued for 60 min before the clamp was removed and two lung ventilation (TLV) started. TLV was continued for 30 to 60 min. Blood and lung biopsies were taken immediately before OLV, 30 min and 60 min of OLV and after restoration of TLV. Histological analyses revealed that the non-ventilated lung was totally collapsed during OLV. On reventilation, there was clear evidence of vascular congestion and alveolar wall thickening at 30 min after TLV. At 60 min of TLV, there was still vascular congestion. Serum nitrite levels (as an index of nitric oxide production) showed steady decline over the course of the experimental period, reaching a significantly low level on reventilation (compared with baseline levels before OLV). Lung MPO activity (marker of neutrophil sequestration) and serum TNFalpha levels were not raised during the entire experimental period. These results suggest that there was lung vascular injury after OLV, which was associated with reduced levels of nitric oxide production and not associated with an inflammatory response.

Comparison between conventional protective mechanical ventilation and high-frequency oscillatory ventilation associated with the prone position.

PubMed

Fioretto, José Roberto; Klefens, Susiane Oliveira; Pires, Rafaelle Fernandes; Kurokawa, Cilmery Suemi; Carpi, Mario Ferreira; Bonatto, Rossano César; Moraes, Marcos Aurélio; Ronchi, Carlos Fernando

2017-01-01

To compare the effects of high-frequency oscillatory ventilation and conventional protective mechanical ventilation associated with the prone position on oxygenation, histology and pulmonary oxidative damage in an experimental model of acute lung injury. Forty-five rabbits with tracheostomy and vascular access were underwent mechanical ventilation. Acute lung injury was induced by tracheal infusion of warm saline. Three experimental groups were formed: healthy animals + conventional protective mechanical ventilation, supine position (Control Group; n = 15); animals with acute lung injury + conventional protective mechanical ventilation, prone position (CMVG; n = 15); and animals with acute lung injury + high-frequency oscillatory ventilation, prone position (HFOG; n = 15). Ten minutes after the beginning of the specific ventilation of each group, arterial gasometry was collected, with this timepoint being called time zero, after which the animal was placed in prone position and remained in this position for 4 hours. Oxidative stress was evaluated by the total antioxidant performance assay. Pulmonary tissue injury was determined by histopathological score. The level of significance was 5%. Both groups with acute lung injury showed worsening of oxygenation after induction of injury compared with the Control Group. After 4 hours, there was a significant improvement in oxygenation in the HFOG group compared with CMVG. Analysis of total antioxidant performance in plasma showed greater protection in HFOG. HFOG had a lower histopathological lesion score in lung tissue than CMVG. High-frequency oscillatory ventilation, associated with prone position, improves oxygenation and attenuates oxidative damage and histopathological lung injury compared with conventional protective mechanical ventilation.

Comparison between conventional protective mechanical ventilation and high-frequency oscillatory ventilation associated with the prone position

PubMed Central

Fioretto, José Roberto; Klefens, Susiane Oliveira; Pires, Rafaelle Fernandes; Kurokawa, Cilmery Suemi; Carpi, Mario Ferreira; Bonatto, Rossano César; Moraes, Marcos Aurélio; Ronchi, Carlos Fernando

2017-01-01

Objective To compare the effects of high-frequency oscillatory ventilation and conventional protective mechanical ventilation associated with the prone position on oxygenation, histology and pulmonary oxidative damage in an experimental model of acute lung injury. Methods Forty-five rabbits with tracheostomy and vascular access were underwent mechanical ventilation. Acute lung injury was induced by tracheal infusion of warm saline. Three experimental groups were formed: healthy animals + conventional protective mechanical ventilation, supine position (Control Group; n = 15); animals with acute lung injury + conventional protective mechanical ventilation, prone position (CMVG; n = 15); and animals with acute lung injury + high-frequency oscillatory ventilation, prone position (HFOG; n = 15). Ten minutes after the beginning of the specific ventilation of each group, arterial gasometry was collected, with this timepoint being called time zero, after which the animal was placed in prone position and remained in this position for 4 hours. Oxidative stress was evaluated by the total antioxidant performance assay. Pulmonary tissue injury was determined by histopathological score. The level of significance was 5%. Results Both groups with acute lung injury showed worsening of oxygenation after induction of injury compared with the Control Group. After 4 hours, there was a significant improvement in oxygenation in the HFOG group compared with CMVG. Analysis of total antioxidant performance in plasma showed greater protection in HFOG. HFOG had a lower histopathological lesion score in lung tissue than CMVG. Conclusion High-frequency oscillatory ventilation, associated with prone position, improves oxygenation and attenuates oxidative damage and histopathological lung injury compared with conventional protective mechanical ventilation. PMID:29236845

Intraoperative mechanical ventilation strategies in patients undergoing one-lung ventilation: a meta-analysis.

PubMed

Liu, Zhen; Liu, Xiaowen; Huang, Yuguang; Zhao, Jing

2016-01-01

Postoperative pulmonary complications (PPCs), which are not uncommon in one-lung ventilation, are among the main causes of postoperative death after lung surgery. Intra-operative ventilation strategies can influence the incidence of PPCs. High tidal volume (V T) and increased airway pressure may lead to lung injury, while pressure-controlled ventilation and lung-protective strategies with low V T may have protective effects against lung injury. In this meta-analysis, we aim to investigate the effects of different ventilation strategies, including pressure-controlled ventilation (PCV), volume-controlled ventilation (VCV), protective ventilation (PV) and conventional ventilation (CV), on PPCs in patients undergoing one-lung ventilation. We hypothesize that both PV with low V T and PCV have protective effects against PPCs in one-lung ventilation. A systematic search (PubMed, EMBASE, the Cochrane Library, and Ovid MEDLINE; in May 2015) was performed for randomized trials comparing PCV with VCV or comparing PV with CV in one-lung ventilation. Methodological quality was evaluated using the Cochrane tool for risk. The primary outcome was the incidence of PPCs. The secondary outcomes included the length of hospital stay, intraoperative plateau airway pressure (Pplateau), oxygen index (PaO2/FiO2) and mean arterial pressure (MAP). In this meta-analysis, 11 studies (436 patients) comparing PCV with VCV and 11 studies (657 patients) comparing PV with CV were included. Compared to CV, PV decreased the incidence of PPCs (OR 0.29; 95 % CI 0.15-0.57; P < 0.01) and intraoperative Pplateau (MD -3.75; 95 % CI -5.74 to -1.76; P < 0.01) but had no significant influence on the length of hospital stay or MAP. Compared to VCV, PCV decreased intraoperative Pplateau (MD -1.46; 95 % CI -2.54 to -0.34; P = 0.01) but had no significant influence on PPCs, PaO2/FiO2 or MAP. PV with low V T was associated with the reduced incidence of PPCs compared to CV. However, PCV and VCV had similar effects on the incidence of PPCs.

WE-AB-202-04: Statistical Evaluation of Lung Function Using 4DCT Ventilation Imaging: Proton Therapy VS IMRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Q; Zhang, M; Chen, T

Purpose: Variation in function of different lung regions has been ignored so far for conventional lung cancer treatment planning, which may lead to higher risk of radiation induced lung disease. 4DCT based lung ventilation imaging provides a novel yet convenient approach for lung functional imaging as 4DCT is taken as routine for lung cancer treatment. Our work aims to evaluate the impact of accounting for spatial heterogeneity in lung function using 4DCT based lung ventilation imaging for proton and IMRT plans. Methods: Six patients with advanced stage lung cancer of various tumor locations were retrospectively evaluated for the study. Protonmore » and IMRT plans were designed following identical planning objective and constrains for each patient. Ventilation images were calculated from patients’ 4DCT using deformable image registration implemented by Velocity AI software based on Jacobian-metrics. Lung was delineated into two function level regions based on ventilation (low and high functional area). High functional region was defined as lung ventilation greater than 30%. Dose distribution and statistics in different lung function area was calculated for patients. Results: Variation in dosimetric statistics of different function lung region was observed between proton and IMRT plans. In all proton plans, high function lung regions receive lower maximum dose (100.2%–108.9%), compared with IMRT plans (106.4%–119.7%). Interestingly, three out of six proton plans gave higher mean dose by up to 2.2% than IMRT to high function lung region. Lower mean dose (lower by up to 14.1%) and maximum dose (lower by up to 9%) were observed in low function lung for proton plans. Conclusion: A systematic approach was developed to generate function lung ventilation imaging and use it to evaluate plans. This method hold great promise in function analysis of lung during planning. We are currently studying more subjects to evaluate this tool.« less

Negative pressure ventilation decreases inflammation and lung edema during normothermic ex-vivo lung perfusion.

PubMed

Aboelnazar, Nader S; Himmat, Sayed; Hatami, Sanaz; White, Christopher W; Burhani, Mohamad S; Dromparis, Peter; Matsumura, Nobutoshi; Tian, Ganghong; Dyck, Jason R B; Mengel, Michael; Freed, Darren H; Nagendran, Jayan

2018-04-01

Normothermic ex-vivo lung perfusion (EVLP) using positive pressure ventilation (PPV) and both acellular and red blood cell (RBC)-based perfusate solutions have increased the rate of donor organ utilization. We sought to determine whether a negative pressure ventilation (NPV) strategy would improve donor lung assessment during EVLP. Thirty-two pig lungs were perfused ex vivo for 12 hours in a normothermic state, and were allocated equally to 4 groups according to the mode of ventilation (positive pressure ventilation [PPV] vs NPV) and perfusate composition (acellular vs RBC). The impact of ventilation strategy on the preservation of 6 unutilized human donor lungs was also evaluated. Physiologic parameters, cytokine profiles, lung injury, bullae and edema formation were compared between treatment groups. Perfused lungs demonstrated acceptable oxygenation (partial pressure of arterial oxygen/fraction of inspired oxygen ratio >350 mm Hg) and physiologic parameters. However, there was less generation of pro-inflammatory cytokines (tumor necrosis factor-α, interleukin-6 and interleukin-8) in human and pig lungs perfused, irrespective of perfusate solution used, when comparing NPV with PPV (p < 0.05), and a reduction in bullae formation with an NPV modality (p = 0.02). Pig lungs developed less edema with NPV (p < 0.01), and EVLP using an acellular perfusate solution had greater edema formation, irrespective of ventilation strategy (p = 0.01). Interestingly, human lungs perfused with NPV developed negative edema, or "drying" (p < 0.01), and lower composite acute lung injury (p < 0.01). Utilization of an NPV strategy during extended EVLP is associated with significantly less inflammation, and lung injury, irrespective of perfusate solution composition. Copyright © 2018 International Society for the Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Low-Flow Extracorporeal Carbon Dioxide Removal Using the Hemolung Respiratory Dialysis System® to Facilitate Lung-Protective Mechanical Ventilation in Acute Respiratory Distress Syndrome.

PubMed

Akkanti, Bindu; Rajagopal, Keshava; Patel, Kirti P; Aravind, Sangeeta; Nunez-Centanu, Emmanuel; Hussain, Rahat; Shabari, Farshad Raissi; Hofstetter, Wayne L; Vaporciyan, Ara A; Banjac, Igor S; Kar, Biswajit; Gregoric, Igor D; Loyalka, Pranav

2017-06-01

Extracorporeal carbon dioxide removal (ECCO 2 R) permits reductions in alveolar ventilation requirements that the lungs would otherwise have to provide. This concept was applied to a case of hypercapnia refractory to high-level invasive mechanical ventilator support. We present a case of an 18-year-old man who developed post-pneumonectomy acute respiratory distress syndrome (ARDS) after resection of a mediastinal germ cell tumor involving the left lung hilum. Hypercapnia and hypoxemia persisted despite ventilator support even at traumatic levels. ECCO 2 R using a miniaturized system was instituted and provided effective carbon dioxide elimination. This facilitated establishment of lung-protective ventilator settings and lung function recovery. Extracorporeal lung support increasingly is being applied to treat ARDS. However, conventional extracorporeal membrane oxygenation (ECMO) generally involves using large cannulae capable of carrying high flow rates. A subset of patients with ARDS has mixed hypercapnia and hypoxemia despite high-level ventilator support. In the absence of profound hypoxemia, ECCO 2 R may be used to reduce ventilator support requirements to lung-protective levels, while avoiding risks associated with conventional ECMO.

[Losartan regulates oxidative stress via caveolin-1 and NOX4 in mice with ventilator- induced lung injury].

PubMed

Ling, Xuguang; Lou, Anni; Li, Yang; Yang, Renqiang; Ning, Zuowei; Li, Xu

2015-12-01

To investigate the effect of losartan in regulating oxidative stress and the underlying mechanism in mice with ventilator-induced lung injury. Thirty-six male C57 mice were randomly divided into control group, losartan treatment group, mechanical ventilation model group, and ventilation plus losartan treatment group. After the corresponding treatments, the lung injuries in each group were examined and the expressions of caveolin-1 and NOX4 in the lung tissues were detected. The mean Smith score of lung injury was significantly higher in mechanical ventilation model group (3.3) than in the control group (0.4), and losartan treatment group (0.3); the mean score was significantly lowered in ventilation plus losartan treatment group (2.3) compared with that in the model group (P<0.05). The expressions of caveolin-1 and NOX4 were significantly higher in the model group than in the control and losartan treatment groups (P<0.05) but was obviously lowered after losartan treatment (P<0.05). Co-expression of caveolin-1 and NOX4 in the lungs was observed in the model group, and was significantly decreased after losartan treatment. Losartan can alleviate ventilator-induced lung injury in mice and inhibit the expression of caveolin-1 and NOX4 and their interaction in the lungs.

A prototype of volume-controlled tidal liquid ventilator using independent piston pumps.

PubMed

Robert, Raymond; Micheau, Philippe; Cyr, Stéphane; Lesur, Olivier; Praud, Jean-Paul; Walti, Hervé

2006-01-01

Liquid ventilation using perfluorochemicals (PFC) offers clear theoretical advantages over gas ventilation, such as decreased lung damage, recruitment of collapsed lung regions, and lavage of inflammatory debris. We present a total liquid ventilator designed to ventilate patients with completely filled lungs with a tidal volume of PFC liquid. The two independent piston pumps are volume controlled and pressure limited. Measurable pumping errors are corrected by a programmed supervisor module, which modifies the inserted or withdrawn volume. Pump independence also allows easy functional residual capacity modifications during ventilation. The bubble gas exchanger is divided into two sections such that the PFC exiting the lungs is not in contact with the PFC entering the lungs. The heating system is incorporated into the metallic base of the gas exchanger, and a heat-sink-type condenser is placed on top of the exchanger to retrieve PFC vapors. The prototype was tested on 5 healthy term newborn lambs (<5 days old). The results demonstrate the efficiency and safety of the prototype in maintaining adequate gas exchange, normal acido-basis equilibrium, and cardiovascular stability during a short, 2-hour total liquid ventilator. Airway pressure, lung volume, and ventilation scheme were maintained in the targeted range.

Intravenous superoxide dismutase as a protective agent to prevent impairment of lung function induced by high tidal volume ventilation.

PubMed

Wu, Nan-Chun; Liao, Fan-Ting; Cheng, Hao-Min; Sung, Shih-Hsien; Yang, Yu-Chun; Wang, Jiun-Jr

2017-07-26

Positive-pressure mechanical ventilation is essential in assisting patients with respiratory failure in the intensive care unit and facilitating oxygenation in the operating room. However, it was also recognized as a primary factor leading to hospital-acquired pulmonary dysfunction, in which pulmonary oxidative stress and lung inflammation had been known to play important roles. Cu/Zn superoxide dismutase (SOD) is an important antioxidant, and possesses anti-inflammatory capacity. In this study, we aimed to study the efficacy of Cu/Zn SOD, administered intravenously during high tidal volume (HTV) ventilation, to prevent impairment of lung function. Thirty-eight male Sprague-Dawley rats were divided into 3 groups: 5 h ventilation with (A) low tidal volume (LTV; 8 mL/kg; n = 10), (B) high tidal volume (HTV; 18 mL/kg; n = 14), or (C) HTV and intravenous treatment of Cu/Zn SOD at a dose of 1000 U/kg/h (HTV + SOD; n = 14). Lung function was evaluated both at baseline and after 5-h ventilation. Lung injury was assessed by histological examination, lung water and protein contents in the bronchoalveolar lavage fluid (BALF). Pulmonary oxidative stress was examined by concentrations of methylguanidine (MG) and malondialdehyde (MDA) in BALF, and antioxidative activity by protein expression of glutathione peroxidase-1 (GPx-1) in the lung. Severity of lung inflammation was evaluated by white blood cell and differential count in BALF, and protein expression of inducible nitric oxide synthase (iNOS), intercellular adhesion molecule-1 (ICAM-1), tumor necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9), and mRNA expression of nuclear factor-κB (NF-κB) in the lung. We also examined protein expression of surfactant protein (SP)-A and D and we measured hourly changes in serum nitric oxide (NO) level. Five hours of LTV ventilation did not induce a major change in lung function, whereas 5 h of HTV ventilation induced apparent combined restrictive and obstructive lung disorder, together with increased pulmonary oxidative stress, decreased anti-oxidative activity and increased lung inflammation (P < 0.05). HTV ventilation also decreased SP-A and SP-D expression and suppressed serum NO level during the time course of ventilation. Cu/Zn SOD administered intravenously during HTV ventilation effectively reversed associated pulmonary oxidative stress and lung inflammation (P < 0.05); moreover, it preserved SP-A and SP-D expressions in the lung and increased serum nitric oxide (NO) level, enhancing vascular NO bioavailability. HTV ventilation can induce combined restrictive and obstructive lung disorders. Intravenous administration of Cu/Zn SOD during HTV ventilation can prevent lung function impairment and lung injury via reducing pulmonary oxidative stress and lung inflammation, preserving pulmonary surfactant expression, and enhancing vascular NO bioavailability.

Applications and interpretation of krypton 81m ventilation/technetium 99m macroaggregate perfusion lung scanning in childhood

NASA Astrophysics Data System (ADS)

Davies, Hugh Trevor Frimston

Radionuclide ventilation perfusion lung scans now play an important part in the investigation of paediatric lung disease, providing a safe, noninvasive assessment of regional lung function in children with suspected pulmonary disease. In paediatric practice the most suitable radionuclides are Krypton 81m (Kr81m) and Technetium 99m (Tc99m), which are jointly used in the Kr81m ventilation/Tc99m macroaggregate perfusion lung scan (V/Q lung scan). The Kr81m ventilation scan involves a low radiation dose, requires little or no subject cooperation and because of the very short half life of Kr81m (13 seconds) the steady state image acquired during continuous inhalation of the radionuclide is considered to reflect regional distribution of ventilation. It is now the most important noninvasive method available for the investigation of the regional abnormalities of ventilation characteristic of many congenital and acquired paediatric respiratory diseases, such as diaphragmatic hernia, pulmonary sequestration, bronchopulmonary dysplasia, foreign body inhalation and bronchiectasis. It improves diagnostic accuracy, aids clinical decision making and is used to monitor the progress of disease and response to therapy. Theoretical analysis of the steady state Kr81m ventilation image suggests that it may only reflect regional ventilation when specific ventilation (ventilation per unit volume of lung) is within or below the normal adult range (1-3 L/L/min). At higher values such as those seen in neonates and infants (8-15 L/L/min) Kr81m activity may reflect regional lung volume rather than ventilation, a conclusion supported by the studies of Ciofetta et al. There is some controversy on this issue as animal studies have demonstrated that the Kr81m image reflects ventilation over a much wider range of specific ventilation (up to 13 L/L/min). A clinical study of sick infants and very young children is in agreement with this animal work and suggests that the steady state Kr81m image still reflects regional ventilation in this age group. The doubt cast on the interpretation of the Kr81m steady state image could limit the value of V/Q lung scans in following regional lung function through childhood, a period when specific ventilation is falling rapidly as the child grows. Therefore the first aim of this study was to examine the application of this theoretical model to children and determine whether the changing specific ventilation seen through childhood significantly alters the interpretation of the steady state Kr81m image. This is a necessary first step before conducting longitudinal studies of regional ventilation and perfusion in children. The effect of posture on regional ventilation and perfusion in the adult human lung has been extensively studied. Radiotracer studies have consistently shown that both ventilation and perfusion are preferentially distributed to dependent lung regions during tidal breathing regardless of posture. There is little published information concerning the pattern in children yet there are many differences in lung and chest wall mechanics of children and adults which, along with clinical observation, have led to the hypothesis that the pattern of regional ventilation observed in adults may not be seen in children. Recent reports of regional ventilation in infants and very young children have provided support for this theory. The paper of Heaf et al demonstrated that these differences may in certain circumstances be clinically important. It is not clear however at what age children adopt the "adult pattern of ventilation". In addition to the problems referred to above, attenuation of Kr81m activity as it passes through the chest wall and the changing geometry of the chest during tidal breathing have made quantitative analysis of the image difficult although fractional ventilation and perfusion to each lung can be calculated from the steady state image. In clinical practise, therefore, ventilation and perfusion are usually assessed by inspection of the steady state image. The aims of the present study were therefore: 1. To critically assess Kr81m ventilation and Tc99m MAA perfusion images in children. 2. To derive fractional ventilation and perfusion to each lung in children with normal chest radiography and homogeneous distribution of the radionuclides. 3. To conduct further studies into the effects of gravity on regional lung function. 4. To apply the technique in clinical practise. 5. To attempt to improve quantitation of the Kr81m ventilation image.

Downregulated Smad4 Affects Extracellular Matrix Remodeling in Ventilator-induced Lung Injury.

PubMed

Huang, Xiaofang; Zhou, Wei; Ding, Shifang

2016-09-01

To explore the effect of Smad4 on the extracellular matrix remodeling in ventilator-induced lung injury (VILI). We randomized 24 C57BL/6 mice to 4 groups for treatment (n=6/group): control, ventilation, non-targeted (scramble) lentivirus transfection plus ventilation, and Smad4 small interfering RNA (siRNA) lentivirus transfection plus ventilation. Lentivirus was delivered by intranasal instillation. Four weeks later, the 3 ventilated groups underwent high tidal volume (VT 40mL/kg) ventilation to induce lung injury. After 72 hours, lungs were collected from the anesthetized live mice. Histological changes in lungs were evaluated by hematoxylin and eosin and Masson's staining. The expression of α-smooth muscle actin (α-SMA) was determined by immunohistochemistry, and the mRNA and protein levels of Smad4, α-SMA, and collagen I and III were detected by quantitative real-time PCR and western blotting analysis. Smad4 siRNAs significantly knocked down Smad4 expression (P<.05), which was increased with ventilation, thereby alleviating inflammatory cell infiltration. It also inhibited accumulation of α-SMA-positive myofibroblasts and pulmonary fibrosis, as seen by reduced collagen I and III expression (P<.05), induced by ventilation. Scramble siRNA treatment had no effect (P>.05). Smad4 gene silencing may be a therapeutic target for treating ventilator-induced lung injury and pulmonary fibrosis. © 2016 by the Association of Clinical Scientists, Inc.

Higher levels of spontaneous breathing reduce lung injury in experimental moderate acute respiratory distress syndrome.

PubMed

Carvalho, Nadja C; Güldner, Andreas; Beda, Alessandro; Rentzsch, Ines; Uhlig, Christopher; Dittrich, Susanne; Spieth, Peter M; Wiedemann, Bärbel; Kasper, Michael; Koch, Thea; Richter, Torsten; Rocco, Patricia R; Pelosi, Paolo; de Abreu, Marcelo Gama

2014-11-01

To assess the effects of different levels of spontaneous breathing during biphasic positive airway pressure/airway pressure release ventilation on lung function and injury in an experimental model of moderate acute respiratory distress syndrome. Multiple-arm randomized experimental study. University hospital research facility. Thirty-six juvenile pigs. Pigs were anesthetized, intubated, and mechanically ventilated. Moderate acute respiratory distress syndrome was induced by repetitive saline lung lavage. Biphasic positive airway pressure/airway pressure release ventilation was conducted using the airway pressure release ventilation mode with an inspiratory/expiratory ratio of 1:1. Animals were randomly assigned to one of four levels of spontaneous breath in total minute ventilation (n = 9 per group, 6 hr each): 1) biphasic positive airway pressure/airway pressure release ventilation, 0%; 2) biphasic positive airway pressure/airway pressure release ventilation, > 0-30%; 3) biphasic positive airway pressure/airway pressure release ventilation, > 30-60%, and 4) biphasic positive airway pressure/airway pressure release ventilation, > 60%. The inspiratory effort measured by the esophageal pressure time product increased proportionally to the amount of spontaneous breath and was accompanied by improvements in oxygenation and respiratory system elastance. Compared with biphasic positive airway pressure/airway pressure release ventilation of 0%, biphasic positive airway pressure/airway pressure release ventilation more than 60% resulted in lowest venous admixture, as well as peak and mean airway and transpulmonary pressures, redistributed ventilation to dependent lung regions, reduced the cumulative diffuse alveolar damage score across lungs (median [interquartile range], 11 [3-40] vs 18 [2-69]; p < 0.05), and decreased the level of tumor necrosis factor-α in ventral lung tissue (median [interquartile range], 17.7 pg/mg [8.4-19.8] vs 34.5 pg/mg [29.9-42.7]; p < 0.05). Biphasic positive airway pressure/airway pressure release ventilation more than 0-30% and more than 30-60% showed a less consistent pattern of improvement in lung function, inflammation, and damage compared with biphasic positive airway pressure/airway pressure release ventilation more than 60%. In this model of moderate acute respiratory distress syndrome in pigs, biphasic positive airway pressure/airway pressure release ventilation with levels of spontaneous breath higher than usually seen in clinical practice, that is, more than 30% of total minute ventilation, reduced lung injury with improved respiratory function, as compared with protective controlled mechanical ventilation.

Protective ventilation of preterm lambs exposed to acute chorioamnionitis does not reduce ventilation-induced lung or brain injury.

PubMed

Barton, Samantha K; Moss, Timothy J M; Hooper, Stuart B; Crossley, Kelly J; Gill, Andrew W; Kluckow, Martin; Zahra, Valerie; Wong, Flora Y; Pichler, Gerhard; Galinsky, Robert; Miller, Suzanne L; Tolcos, Mary; Polglase, Graeme R

2014-01-01

The onset of mechanical ventilation is a critical time for the initiation of cerebral white matter (WM) injury in preterm neonates, particularly if they are inadvertently exposed to high tidal volumes (VT) in the delivery room. Protective ventilation strategies at birth reduce ventilation-induced lung and brain inflammation and injury, however its efficacy in a compromised newborn is not known. Chorioamnionitis is a common antecedent of preterm birth, and increases the risk and severity of WM injury. We investigated the effects of high VT ventilation, after chorioamnionitis, on preterm lung and WM inflammation and injury, and whether a protective ventilation strategy could mitigate the response. Pregnant ewes (n = 18) received intra-amniotic lipopolysaccharide (LPS) 2 days before delivery, instrumentation and ventilation at 127±1 days gestation. Lambs were either immediately euthanased and used as unventilated controls (LPSUVC; n = 6), or were ventilated using an injurious high VT strategy (LPSINJ; n = 5) or a protective ventilation strategy (LPSPROT; n = 7) for a total of 90 min. Mean arterial pressure, heart rate and cerebral haemodynamics and oxygenation were measured continuously. Lungs and brains underwent molecular and histological assessment of inflammation and injury. LPSINJ lambs had poorer oxygenation than LPSPROT lambs. Ventilation requirements and cardiopulmonary and systemic haemodynamics were not different between ventilation strategies. Compared to unventilated lambs, LPSINJ and LPSPROT lambs had increases in pro-inflammatory cytokine expression within the lungs and brain, and increased astrogliosis (p<0.02) and cell death (p<0.05) in the WM, which were equivalent in magnitude between groups. Ventilation after acute chorioamnionitis, irrespective of strategy used, increases haemodynamic instability and lung and cerebral inflammation and injury. Mechanical ventilation is a potential contributor to WM injury in infants exposed to chorioamnionitis.

Respiratory mechanics in brain injury: A review.

PubMed

Koutsoukou, Antonia; Katsiari, Maria; Orfanos, Stylianos E; Kotanidou, Anastasia; Daganou, Maria; Kyriakopoulou, Magdalini; Koulouris, Nikolaos G; Rovina, Nikoletta

2016-02-04

Several clinical and experimental studies have shown that lung injury occurs shortly after brain damage. The responsible mechanisms involve neurogenic pulmonary edema, inflammation, the harmful action of neurotransmitters, or autonomic system dysfunction. Mechanical ventilation, an essential component of life support in brain-damaged patients (BD), may be an additional traumatic factor to the already injured or susceptible to injury lungs of these patients thus worsening lung injury, in case that non lung protective ventilator settings are applied. Measurement of respiratory mechanics in BD patients, as well as assessment of their evolution during mechanical ventilation, may lead to preclinical lung injury detection early enough, allowing thus the selection of the appropriate ventilator settings to avoid ventilator-induced lung injury. The aim of this review is to explore the mechanical properties of the respiratory system in BD patients along with the underlying mechanisms, and to translate the evidence of animal and clinical studies into therapeutic implications regarding the mechanical ventilation of these critically ill patients.

Effects of ventilation strategy on distribution of lung inflammatory cell activity

PubMed Central

2013-01-01

Introduction Leukocyte infiltration is central to the development of acute lung injury, but it is not known how mechanical ventilation strategy alters the distribution or activation of inflammatory cells. We explored how protective (vs. injurious) ventilation alters the magnitude and distribution of lung leukocyte activation following systemic endotoxin administration. Methods Anesthetized sheep received intravenous endotoxin (10 ng/kg/min) followed by 2 h of either injurious or protective mechanical ventilation (n = 6 per group). We used positron emission tomography to obtain images of regional perfusion and shunting with infused 13N[nitrogen]-saline and images of neutrophilic inflammation with 18F-fluorodeoxyglucose (18F-FDG). The Sokoloff model was used to quantify 18F-FDG uptake (Ki), as well as its components: the phosphorylation rate (k3, a surrogate of hexokinase activity) and the distribution volume of 18F-FDG (Fe) as a fraction of lung volume (Ki = Fe × k3). Regional gas fractions (fgas) were assessed by examining transmission scans. Results Before endotoxin administration, protective (vs. injurious) ventilation was associated with a higher ratio of partial pressure of oxygen in arterial blood to fraction of inspired oxygen (PaO2/FiO2) (351 ± 117 vs. 255 ± 74 mmHg; P < 0.01) and higher whole-lung fgas (0.71 ± 0.12 vs. 0.48 ± 0.08; P = 0.004), as well as, in dependent regions, lower shunt fractions. Following 2 h of endotoxemia, PaO2/FiO2 ratios decreased in both groups, but more so with injurious ventilation, which also increased the shunt fraction in dependent lung. Protective ventilation resulted in less nonaerated lung (20-fold; P < 0.01) and more normally aerated lung (14-fold; P < 0.01). Ki was lower during protective (vs. injurious) ventilation, especially in dependent lung regions (0.0075 ± 0.0043/min vs. 0.0157 ± 0.0072/min; P < 0.01). 18F-FDG phosphorylation rate (k3) was twofold higher with injurious ventilation and accounted for most of the between-group difference in Ki. Dependent regions of the protective ventilation group exhibited lower k3 values per neutrophil than those in the injurious ventilation group (P = 0.01). In contrast, Fe was not affected by ventilation strategy (P = 0.52). Lung neutrophil counts were not different between groups, even when regional inflation was accounted for. Conclusions During systemic endotoxemia, protective ventilation may reduce the magnitude and heterogeneity of pulmonary inflammatory cell metabolic activity in early lung injury and may improve gas exchange through its effects predominantly in dependent lung regions. Such effects are likely related to a reduction in the metabolic activity, but not in the number, of lung-infiltrating neutrophils. PMID:23947920

Correlation between alveolar ventilation and electrical properties of lung parenchyma.

PubMed

Roth, Christian J; Ehrl, Andreas; Becher, Tobias; Frerichs, Inéz; Schittny, Johannes C; Weiler, Norbert; Wall, Wolfgang A

2015-06-01

One key problem in modern medical imaging is linking measured data and actual physiological quantities. In this article we derive such a link between the electrical bioimpedance of lung parenchyma, which can be measured by electrical impedance tomography (EIT), and the magnitude of regional ventilation, a key to understanding lung mechanics and developing novel protective ventilation strategies. Two rat-derived three-dimensional alveolar microstructures obtained from synchrotron-based x-ray tomography are each exposed to a constant potential difference for different states of ventilation in a finite element simulation. While the alveolar wall volume remains constant during stretch, the enclosed air volume varies, similar to the lung volume during ventilation. The enclosed air, serving as insulator in the alveolar ensemble, determines the resulting current and accordingly local tissue bioimpedance. From this we can derive a relationship between lung tissue bioimpedance and regional alveolar ventilation. The derived relationship shows a linear dependence between air content and tissue impedance and matches clinical data determined from a ventilated patient at the bedside.

Mesenchymal Stem Cell Attenuates Neutrophil-predominant Inflammation and Acute Lung Injury in an In Vivo Rat Model of Ventilator-induced Lung Injury

PubMed Central

Lai, Tian-Shun; Wang, Zhi-Hong; Cai, Shao-Xi

2015-01-01

Background: Subsequent neutrophil (polymorphonuclear neutrophil [PMN])-predominant inflammatory response is a predominant feature of ventilator-induced lung injury (VILI), and mesenchymal stem cell (MSC) can improve mice survival model of endotoxin-induced acute lung injury, reduce lung impairs, and enhance the repair of VILI. However, whether MSC could attenuate PMN-predominant inflammatory in the VILI is still unknown. This study aimed to test whether MSC intervention could attenuate the PMN-predominate inflammatory in the mechanical VILI. Methods: Sprague-Dawley rats were ventilated for 2 hours with large tidal volume (20 mL/kg). MSCs were given before or after ventilation. The inflammatory chemokines and gas exchange were observed and compared dynamically until 4 hours after ventilation, and pulmonary pathological change and activation of PMN were observed and compared 4 hours after ventilation. Results: Mechanical ventilation (MV) caused significant lung injury reflected by increasing in PMN pulmonary sequestration, inflammatory chemokines (tumor necrosis factor-alpha, interleukin-6 and macrophage inflammatory protein 2) in the bronchoalveolar lavage fluid, and injury score of the lung tissue. These changes were accompanied with excessive PMN activation which reflected by increases in PMN elastase activity, production of radical oxygen series. MSC intervention especially pretreatment attenuated subsequent lung injury, systemic inflammation response and PMN pulmonary sequestration and excessive PMN activation initiated by injurious ventilation. Conclusions: MV causes profound lung injury and PMN-predominate inflammatory responses. The protection effect of MSC in the VILI rat model is related to the suppression of the PMN activation. PMID:25635432

History of Mechanical Ventilation. From Vesalius to Ventilator-induced Lung Injury.

PubMed

Slutsky, Arthur S

2015-05-15

Mechanical ventilation is a life-saving therapy that catalyzed the development of modern intensive care units. The origins of modern mechanical ventilation can be traced back about five centuries to the seminal work of Andreas Vesalius. This article is a short history of mechanical ventilation, tracing its origins over the centuries to the present day. One of the great advances in ventilatory support over the past few decades has been the development of lung-protective ventilatory strategies, based on our understanding of the iatrogenic consequences of mechanical ventilation such as ventilator-induced lung injury. These strategies have markedly improved clinical outcomes in patients with respiratory failure.

Pressure Dynamic Characteristics of Pressure Controlled Ventilation System of a Lung Simulator

PubMed Central

Shi, Yan; Ren, Shuai; Cai, Maolin; Xu, Weiqing; Deng, Qiyou

2014-01-01

Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems. PMID:25197318

Variability in usual care mechanical ventilation for pediatric acute lung injury: the potential benefit of a lung protective computer protocol.

PubMed

Khemani, Robinder G; Sward, Katherine; Morris, Alan; Dean, J Michael; Newth, Christopher J L

2011-11-01

Although pediatric intensivists claim to embrace lung protective ventilation for acute lung injury (ALI), ventilator management is variable. We describe ventilator changes clinicians made for children with hypoxemic respiratory failure, and evaluate the potential acceptability of a pediatric ventilation protocol. This was a retrospective cohort study performed in a tertiary care pediatric intensive care unit (PICU). The study period was from January 2000 to July 2007. We included mechanically ventilated children with PaO(2)/FiO(2) (P/F) ratio less than 300. We assessed variability in ventilator management by evaluating actual changes to ventilator settings after an arterial blood gas (ABG). We evaluated the potential acceptability of a pediatric mechanical ventilation protocol we adapted from National Institutes of Health/National Heart, Lung, and Blood Institute (NIH/NHLBI) Acute Respiratory Distress Syndrome (ARDS) Network protocols by comparing actual practice changes in ventilator settings to changes that would have been recommended by the protocol. A total of 2,719 ABGs from 402 patients were associated with 6,017 ventilator settings. Clinicians infrequently decreased FiO(2), even when the PaO(2) was high (>68 mmHg). The protocol would have recommended more positive end expiratory pressure (PEEP) than was used in actual practice 42% of the time in the mid PaO(2) range (55-68 mmHg) and 67% of the time in the low PaO(2) range (<55 mmHg). Clinicians often made no change to either peak inspiratory pressure (PIP) or ventilator rate (VR) when the protocol would have recommended a change, even when the pH was greater than 7.45 with PIP at least 35 cmH(2)O. There may be lost opportunities to minimize potentially injurious ventilator settings for children with ALI. A reproducible pediatric mechanical ventilation protocol could prompt clinicians to make ventilator changes that are consistent with lung protective ventilation.

The effect of donor treatment with hydrogen on lung allograft function in rats.

PubMed

Kawamura, Tomohiro; Huang, Chien-Sheng; Peng, Ximei; Masutani, Kosuke; Shigemura, Norihisa; Billiar, Timothy R; Okumura, Meinoshin; Toyoda, Yoshiya; Nakao, Atsunori

2011-08-01

Because inhaled hydrogen provides potent anti-inflammatory and antiapoptotic effects against acute lung injury, we hypothesized that treatment of organ donors with inhaled hydrogen during mechanical ventilation would decrease graft injury after lung transplantation. Orthotopic left lung transplants were performed using a fully allogeneic Lewis to Brown Norway rat model. The donors were exposed to mechanical ventilation with 98% oxygen plus 2% nitrogen or 2% hydrogen for 3 h prior to harvest, and the lung grafts underwent 4 h of cold storage in Perfadex (Vitrolife, Göteborg, Sweden). The graft function, histomorphologic changes, and inflammatory reactions were assessed. The combination of mechanical ventilation and prolonged cold ischemia resulted in marked deterioration of gas exchange when the donors were ventilated with 2% nitrogen/98% oxygen, which was accompanied by upregulation of proinflammatory cytokines and proapoptotic molecules. These lung injuries were attenuated significantly by ventilation with 2% hydrogen. Inhaled hydrogen induced heme oxygenase-1, an antioxidant enzyme, in the lung grafts prior to implantation, which might contribute to protective effects afforded by hydrogen. Preloaded hydrogen gas during ventilation prior to organ procurement protected lung grafts effectively from ischemia/reperfusion-induced injury in a rat lung transplantation model. Copyright © 2011 Mosby, Inc. All rights reserved.

A multiscale MDCT image-based breathing lung model with time-varying regional ventilation

PubMed Central

Yin, Youbing; Choi, Jiwoong; Hoffman, Eric A.; Tawhai, Merryn H.; Lin, Ching-Long

2012-01-01

A novel algorithm is presented that links local structural variables (regional ventilation and deforming central airways) to global function (total lung volume) in the lung over three imaged lung volumes, to derive a breathing lung model for computational fluid dynamics simulation. The algorithm constitutes the core of an integrative, image-based computational framework for subject-specific simulation of the breathing lung. For the first time, the algorithm is applied to three multi-detector row computed tomography (MDCT) volumetric lung images of the same individual. A key technique in linking global and local variables over multiple images is an in-house mass-preserving image registration method. Throughout breathing cycles, cubic interpolation is employed to ensure C1 continuity in constructing time-varying regional ventilation at the whole lung level, flow rate fractions exiting the terminal airways, and airway deformation. The imaged exit airway flow rate fractions are derived from regional ventilation with the aid of a three-dimensional (3D) and one-dimensional (1D) coupled airway tree that connects the airways to the alveolar tissue. An in-house parallel large-eddy simulation (LES) technique is adopted to capture turbulent-transitional-laminar flows in both normal and deep breathing conditions. The results obtained by the proposed algorithm when using three lung volume images are compared with those using only one or two volume images. The three-volume-based lung model produces physiologically-consistent time-varying pressure and ventilation distribution. The one-volume-based lung model under-predicts pressure drop and yields un-physiological lobar ventilation. The two-volume-based model can account for airway deformation and non-uniform regional ventilation to some extent, but does not capture the non-linear features of the lung. PMID:23794749

Cough augmentation techniques for extubation or weaning critically ill patients from mechanical ventilation.

PubMed

Rose, Louise; Adhikari, Neill Kj; Leasa, David; Fergusson, Dean A; McKim, Douglas

2017-01-11

There are various reasons why weaning and extubation failure occur, but ineffective cough and secretion retention can play a significant role. Cough augmentation techniques, such as lung volume recruitment or manually- and mechanically-assisted cough, are used to prevent and manage respiratory complications associated with chronic conditions, particularly neuromuscular disease, and may improve short- and long-term outcomes for people with acute respiratory failure. However, the role of cough augmentation to facilitate extubation and prevent post-extubation respiratory failure is unclear. Our primary objective was to determine extubation success using cough augmentation techniques compared to no cough augmentation for critically-ill adults and children with acute respiratory failure admitted to a high-intensity care setting capable of managing mechanically-ventilated people (such as an intensive care unit, specialized weaning centre, respiratory intermediate care unit, or high-dependency unit).Secondary objectives were to determine the effect of cough augmentation techniques on reintubation, weaning success, mechanical ventilation and weaning duration, length of stay (high-intensity care setting and hospital), pneumonia, tracheostomy placement and tracheostomy decannulation, and mortality (high-intensity care setting, hospital, and after hospital discharge). We evaluated harms associated with use of cough augmentation techniques when applied via an artificial airway (or non-invasive mask once extubated/decannulated), including haemodynamic compromise, arrhythmias, pneumothorax, haemoptysis, and mucus plugging requiring airway change and the type of person (such as those with neuromuscular disorders or weakness and spinal cord injury) for whom these techniques may be efficacious. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; Issue 4, 2016), MEDLINE (OvidSP) (1946 to April 2016), Embase (OvidSP) (1980 to April 2016), CINAHL (EBSCOhost) (1982 to April 2016), and ISI Web of Science and Conference Proceedings. We searched the PROSPERO and Joanna Briggs Institute databases, websites of relevant professional societies, and conference abstracts from five professional society annual congresses (2011 to 2015). We did not impose language or other restrictions. We performed a citation search using PubMed and examined reference lists of relevant studies and reviews. We contacted corresponding authors for details of additional published or unpublished work. We searched for unpublished studies and ongoing trials on the International Clinical Trials Registry Platform (apps.who.int/trialsearch) (April 2016). We included randomized and quasi-randomized controlled trials that evaluated cough augmentation compared to a control group without this intervention. We included non-randomized studies for assessment of harms. We included studies of adults and of children aged four weeks or older, receiving invasive mechanical ventilation in a high-intensity care setting. Two review authors independently screened titles and abstracts identified by our search methods. Two review authors independently evaluated full-text versions, independently extracted data and assessed risks of bias. We screened 2686 citations and included two trials enrolling 95 participants and one cohort study enrolling 17 participants. We assessed one randomized controlled trial as being at unclear risk of bias, and the other at high risk of bias; we assessed the non-randomized study as being at high risk of bias. We were unable to pool data due to the small number of studies meeting our inclusion criteria and therefore present narrative results rather than meta-analyses. One trial of 75 participants reported that extubation success (defined as no need for reintubation within 48 hours) was higher in the mechanical insufflation-exsufflation (MI-E) group (82.9% versus 52.5%, P < 0.05) (risk ratio (RR) 1.58, 95% confidence interval (CI) 1.13 to 2.20, very low-quality evidence). No study reported weaning success or reintubation as distinct from extubation success. One trial reported a statistically significant reduction in mechanical ventilation duration favouring MI-E (mean difference -6.1 days, 95% CI -8.4 to -3.8, very low-quality evidence). One trial reported mortality, with no participant dying in either study group. Adverse events (reported by two trials) included one participant receiving the MI-E protocol experiencing haemodynamic compromise. Nine (22.5%) of the control group compared to two (6%) MI-E participants experienced secretion encumbrance with severe hypoxaemia requiring reintubation (RR 0.25, 95% CI 0.06 to 1.10). In the lung volume recruitment trial, one participant experienced an elevated blood pressure for more than 30 minutes. No participant experienced new-onset arrhythmias, heart rate increased by more than 25%, or a pneumothorax.For outcomes assessed using GRADE, we based our downgrading decisions on unclear risk of bias, inability to assess consistency or publication bias, and uncertainty about the estimate of effect due to the limited number of studies contributing outcome data. The overall quality of evidence on the efficacy of cough augmentation techniques for critically-ill people is very low. Cough augmentation techniques when used in mechanically-ventilated critically-ill people appear to result in few adverse events.

Recurrent Recruitment Manoeuvres Improve Lung Mechanics and Minimize Lung Injury during Mechanical Ventilation of Healthy Mice

PubMed Central

Reiss, Lucy Kathleen; Kowallik, Anke; Uhlig, Stefan

2011-01-01

Introduction Mechanical ventilation (MV) of mice is increasingly required in experimental studies, but the conditions that allow stable ventilation of mice over several hours have not yet been fully defined. In addition, most previous studies documented vital parameters and lung mechanics only incompletely. The aim of the present study was to establish experimental conditions that keep these parameters within their physiological range over a period of 6 h. For this purpose, we also examined the effects of frequent short recruitment manoeuvres (RM) in healthy mice. Methods Mice were ventilated at low tidal volume VT = 8 mL/kg or high tidal volume VT = 16 mL/kg and a positive end-expiratory pressure (PEEP) of 2 or 6 cmH2O. RM were performed every 5 min, 60 min or not at all. Lung mechanics were followed by the forced oscillation technique. Blood pressure (BP), electrocardiogram (ECG), heart frequency (HF), oxygen saturation and body temperature were monitored. Blood gases, neutrophil-recruitment, microvascular permeability and pro-inflammatory cytokines in bronchoalveolar lavage (BAL) and blood serum as well as histopathology of the lung were examined. Results MV with repetitive RM every 5 min resulted in stable respiratory mechanics. Ventilation without RM worsened lung mechanics due to alveolar collapse, leading to impaired gas exchange. HF and BP were affected by anaesthesia, but not by ventilation. Microvascular permeability was highest in atelectatic lungs, whereas neutrophil-recruitment and structural changes were strongest in lungs ventilated with high tidal volume. The cytokines IL-6 and KC, but neither TNF nor IP-10, were elevated in the BAL and serum of all ventilated mice and were reduced by recurrent RM. Lung mechanics, oxygenation and pulmonary inflammation were improved by increased PEEP. Conclusions Recurrent RM maintain lung mechanics in their physiological range during low tidal volume ventilation of healthy mice by preventing atelectasis and reduce the development of pulmonary inflammation. PMID:21935418

SU-E-J-86: Lobar Lung Function Quantification by PET Galligas and CT Ventilation Imaging in Lung Cancer Patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eslick, E; Kipritidis, J; Keall, P

2014-06-01

Purpose: The purpose of this study was to quantify the lobar lung function using the novel PET Galligas ([68Ga]-carbon nanoparticle) ventilation imaging and the investigational CT ventilation imaging in lung cancer patients pre-treatment. Methods: We present results on our first three lung cancer patients (2 male, mean age 78 years) as part of an ongoing ethics approved study. For each patient a PET Galligas ventilation (PET-V) image and a pair of breath hold CT images (end-exhale and end-inhale tidal volumes) were acquired using a Siemens Biograph PET CT. CT-ventilation (CT-V) images were created from the pair of CT images usingmore » deformable image registration (DIR) algorithms and the Hounsfield Unit (HU) ventilation metric. A comparison of ventilation quantification from each modality was done on the lobar level and the voxel level. A Bland-Altman plot was used to assess the difference in mean percentage contribution of each lobe to the total lung function between the two modalities. For each patient, a voxel-wise Spearmans correlation was calculated for the whole lungs between the two modalities. Results: The Bland-Altman plot demonstrated strong agreement between PET-V and CT-V for assessment of lobar function (r=0.99, p<0.001; range mean difference: −5.5 to 3.0). The correlation between PET-V and CT-V at the voxel level was moderate(r=0.60, p<0.001). Conclusion: This preliminary study on the three patients data sets demonstrated strong agreement between PET and CT ventilation imaging for the assessment of pre-treatment lung function at the lobar level. Agreement was only moderate at the level of voxel correlations. These results indicate that CT ventilation imaging has potential for assessing pre-treatment lobar lung function in lung cancer patients.« less

Quantification of Age-Related Lung Tissue Mechanics under Mechanical Ventilation.

PubMed

Kim, JongWon; Heise, Rebecca L; Reynolds, Angela M; Pidaparti, Ramana M

2017-09-29

Elderly patients with obstructive lung diseases often receive mechanical ventilation to support their breathing and restore respiratory function. However, mechanical ventilation is known to increase the severity of ventilator-induced lung injury (VILI) in the elderly. Therefore, it is important to investigate the effects of aging to better understand the lung tissue mechanics to estimate the severity of ventilator-induced lung injuries. Two age-related geometric models involving human bronchioles from generation G10 to G23 and alveolar sacs were developed. The first is for a 50-year-old (normal) and second is for an 80-year old (aged) model. Lung tissue mechanics of normal and aged models were investigated under mechanical ventilation through computational simulations. Results obtained indicated that lung tissue strains during inhalation (t = 0.2 s) decreased by about 40% in the alveolar sac (G23) and 27% in the bronchiole (G20), respectively, for the 80-year-old as compared to the 50-year-old. The respiratory mechanics parameters (work of breathing per unit volume and maximum tissue strain) over G20 and G23 for the 80-year-old decreased by about 64% (three-fold) and 80% (four-fold), respectively, during the mechanical ventilation breathing cycle. However, there was a significant increase (by about threefold) in lung compliance for the 80-year-old in comparison to the 50-year-old. These findings from the computational simulations demonstrated that lung mechanical characteristics are significantly compromised in aging tissues, and these effects were quantified in this study.

Clinical challenges in mechanical ventilation.

PubMed

Goligher, Ewan C; Ferguson, Niall D; Brochard, Laurent J

2016-04-30

Mechanical ventilation supports gas exchange and alleviates the work of breathing when the respiratory muscles are overwhelmed by an acute pulmonary or systemic insult. Although mechanical ventilation is not generally considered a treatment for acute respiratory failure per se, ventilator management warrants close attention because inappropriate ventilation can result in injury to the lungs or respiratory muscles and worsen morbidity and mortality. Key clinical challenges include averting intubation in patients with respiratory failure with non-invasive techniques for respiratory support; delivering lung-protective ventilation to prevent ventilator-induced lung injury; maintaining adequate gas exchange in severely hypoxaemic patients; avoiding the development of ventilator-induced diaphragm dysfunction; and diagnosing and treating the many pathophysiological mechanisms that impair liberation from mechanical ventilation. Personalisation of mechanical ventilation based on individual physiological characteristics and responses to therapy can further improve outcomes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Airway pressure release ventilation during ex vivo lung perfusion attenuates injury.

PubMed

Mehaffey, J Hunter; Charles, Eric J; Sharma, Ashish K; Money, Dustin T; Zhao, Yunge; Stoler, Mark H; Lau, Christine L; Tribble, Curtis G; Laubach, Victor E; Roeser, Mark E; Kron, Irving L

2017-01-01

Critical organ shortages have resulted in ex vivo lung perfusion gaining clinical acceptance for lung evaluation and rehabilitation to expand the use of donation after circulatory death organs for lung transplantation. We hypothesized that an innovative use of airway pressure release ventilation during ex vivo lung perfusion improves lung function after transplantation. Two groups (n = 4 animals/group) of porcine donation after circulatory death donor lungs were procured after hypoxic cardiac arrest and a 2-hour period of warm ischemia, followed by a 4-hour period of ex vivo lung perfusion rehabilitation with standard conventional volume-based ventilation or pressure-based airway pressure release ventilation. Left lungs were subsequently transplanted into recipient animals and reperfused for 4 hours. Blood gases for partial pressure of oxygen/inspired oxygen fraction ratios, airway pressures for calculation of compliance, and percent wet weight gain during ex vivo lung perfusion and reperfusion were measured. Airway pressure release ventilation during ex vivo lung perfusion significantly improved left lung oxygenation at 2 hours (561.5 ± 83.9 mm Hg vs 341.1 ± 136.1 mm Hg) and 4 hours (569.1 ± 18.3 mm Hg vs 463.5 ± 78.4 mm Hg). Likewise, compliance was significantly higher at 2 hours (26.0 ± 5.2 mL/cm H 2 O vs 15.0 ± 4.6 mL/cm H 2 O) and 4 hours (30.6 ± 1.3 mL/cm H 2 O vs 17.7 ± 5.9 mL/cm H 2 O) after transplantation. Finally, airway pressure release ventilation significantly reduced lung edema development on ex vivo lung perfusion on the basis of percentage of weight gain (36.9% ± 14.6% vs 73.9% ± 4.9%). There was no difference in additional edema accumulation 4 hours after reperfusion. Pressure-directed airway pressure release ventilation strategy during ex vivo lung perfusion improves the rehabilitation of severely injured donation after circulatory death lungs. After transplant, these lungs demonstrate superior lung-specific oxygenation and dynamic compliance compared with lungs ventilated with standard conventional ventilation. This strategy, if implemented into clinical ex vivo lung perfusion protocols, could advance the field of donation after circulatory death lung rehabilitation to expand the lung donor pool. Copyright © 2016 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.

Unilateral empyema impacts the assessment of regional lung ventilation by electrical impedance tomography.

PubMed

Bläser, D; Pulletz, S; Becher, T; Schädler, D; Elke, G; Weiler, N; Frerichs, I

2014-06-01

Several studies have shown the ability of electrical impedance tomography (EIT) to assess regional ventilation distribution in human lungs. Fluid accumulation in the pleural space as in empyema, typically occurring on one chest side, may influence the distribution of ventilation and the corresponding EIT findings. The aim of our study was to examine this effect on the assessment of regional ventilation by EIT. Six patients suffering from unilateral empyema and intubated with a double-lumen endotracheal tube were studied. EIT data were acquired during volume-controlled ventilation with bilateral (tidal volume (V(T)): 800 ml) and unilateral ventilation (V(T): 400 ml) of the right and left lungs. Mean tidal amplitudes of the EIT signal were calculated in all image pixels. The sums of these values, expressed as relative impedance change (rel. ΔZ), were then determined in whole images and functionally defined regions-of-interest (ROI). The sums of rel. ΔZ calculated during the two cases of one-lung ventilation either on the affected or unaffected side were significantly smaller than during bilateral ventilation. However, in contrast to previous findings in patients with no pleural pathology, very low values of rel. ΔZ were found when the lung on the affected side was ventilated. ROI-based analysis rendered higher values than the whole-image analysis in this case, nonetheless, the values were significantly smaller than when the unaffected side was ventilated in spite of identical VT. In conclusion, our results indicate that the presence of empyema may affect the quantitative evaluation of regional lung ventilation by EIT.

A unified approach for EIT imaging of regional overdistension and atelectasis in acute lung injury.

PubMed

Gómez-Laberge, Camille; Arnold, John H; Wolf, Gerhard K

2012-03-01

Patients with acute lung injury or acute respiratory distress syndrome (ALI/ARDS) are vulnerable to ventilator-induced lung injury. Although this syndrome affects the lung heterogeneously, mechanical ventilation is not guided by regional indicators of potential lung injury. We used electrical impedance tomography (EIT) to estimate the extent of regional lung overdistension and atelectasis during mechanical ventilation. Techniques for tidal breath detection, lung identification, and regional compliance estimation were combined with the Graz consensus on EIT lung imaging (GREIT) algorithm. Nine ALI/ARDS patients were monitored during stepwise increases and decreases in airway pressure. Our method detected individual breaths with 96.0% sensitivity and 97.6% specificity. The duration and volume of tidal breaths erred on average by 0.2 s and 5%, respectively. Respiratory system compliance from EIT and ventilator measurements had a correlation coefficient of 0.80. Stepwise increases in pressure could reverse atelectasis in 17% of the lung. At the highest pressures, 73% of the lung became overdistended. During stepwise decreases in pressure, previously-atelectatic regions remained open at sub-baseline pressures. We recommend that the proposed approach be used in collaborative research of EIT-guided ventilation strategies for ALI/ARDS.

Volume-controlled Ventilation Does Not Prevent Injurious Inflation during Spontaneous Effort.

PubMed

Yoshida, Takeshi; Nakahashi, Susumu; Nakamura, Maria Aparecida Miyuki; Koyama, Yukiko; Roldan, Rollin; Torsani, Vinicius; De Santis, Roberta R; Gomes, Susimeire; Uchiyama, Akinori; Amato, Marcelo B P; Kavanagh, Brian P; Fujino, Yuji

2017-09-01

Spontaneous breathing during mechanical ventilation increases transpulmonary pressure and Vt, and worsens lung injury. Intuitively, controlling Vt and transpulmonary pressure might limit injury caused by added spontaneous effort. To test the hypothesis that, during spontaneous effort in injured lungs, limitation of Vt and transpulmonary pressure by volume-controlled ventilation results in less injurious patterns of inflation. Dynamic computed tomography was used to determine patterns of regional inflation in rabbits with injured lungs during volume-controlled or pressure-controlled ventilation. Transpulmonary pressure was estimated by using esophageal balloon manometry [Pl(es)] with and without spontaneous effort. Local dependent lung stress was estimated as the swing (inspiratory change) in transpulmonary pressure measured by intrapleural manometry in dependent lung and was compared with the swing in Pl(es). Electrical impedance tomography was performed to evaluate the inflation pattern in a larger animal (pig) and in a patient with acute respiratory distress syndrome. Spontaneous breathing in injured lungs increased Pl(es) during pressure-controlled (but not volume-controlled) ventilation, but the pattern of dependent lung inflation was the same in both modes. In volume-controlled ventilation, spontaneous effort caused greater inflation and tidal recruitment of dorsal regions (greater than twofold) compared with during muscle paralysis, despite the same Vt and Pl(es). This was caused by higher local dependent lung stress (measured by intrapleural manometry). In injured lungs, esophageal manometry underestimated local dependent pleural pressure changes during spontaneous effort. Limitation of Vt and Pl(es) by volume-controlled ventilation could not eliminate harm caused by spontaneous breathing unless the level of spontaneous effort was lowered and local dependent lung stress was reduced.

Conservative fluid management prevents age-associated ventilator induced mortality.

PubMed

Herbert, Joseph A; Valentine, Michael S; Saravanan, Nivi; Schneck, Matthew B; Pidaparti, Ramana; Fowler, Alpha A; Reynolds, Angela M; Heise, Rebecca L

2016-08-01

Approximately 800 thousand patients require mechanical ventilation in the United States annually with an in-hospital mortality rate of over 30%. The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and in-hospital mortality rates. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress patients, but to date there has been no investigation of the effect of conservative fluid management on VILI and ventilator associated mortality rates. We hypothesized that age-associated increases in susceptibility and incidence of pulmonary edema strongly promote age-related increases in ventilator associated mortality. 2month old and 20month old male C57BL6 mice were mechanically ventilated with either high tidal volume (HVT) or low tidal volume (LVT) for up to 4h with either liberal or conservative fluid support. During ventilation, lung compliance, total lung capacity, and hysteresis curves were quantified. Following ventilation, bronchoalveolar lavage fluid was analyzed for total protein content and inflammatory cell infiltration. Wet to dry ratios were used to directly measure edema in excised lungs. Lung histology was performed to quantify alveolar barrier damage/destruction. Age matched non-ventilated mice were used as controls. At 4h, both advanced age and HVT ventilation significantly increased markers of inflammation and injury, degraded pulmonary mechanics, and decreased survival rates. Conservative fluid support significantly diminished pulmonary edema and improved pulmonary mechanics by 1h in advanced age HVT subjects. In 4h ventilations, conservative fluid support significantly diminished pulmonary edema, improved lung mechanics, and resulted in significantly lower mortality rates in older subjects. Our study demonstrates that conservative fluid alone can attenuate the age associated increase in ventilator associated mortality. Copyright © 2016 Elsevier Inc. All rights reserved.

Conservative Fluid Management Prevents Age-Associated Ventilator Induced Mortality

PubMed Central

Herbert, Joseph A.; Valentine, Michael S.; Saravanan, Nivi; Schneck, Matthew B.; Pidaparti, Ramana; Fowler, Alpha A.; Reynolds, Angela M.; Heise, Rebecca L.

2017-01-01

Background Approximately 800 thousand patients require mechanical ventilation in the United States annually with an in-hospital mortality rate of over 30%. The majority of patients requiring mechanical ventilation are over the age of 65 and advanced age is known to increase the severity of ventilator-induced lung injury (VILI) and in-hosptial mortality rates. However, the mechanisms which predispose aging ventilator patients to increased mortality rates are not fully understood. Ventilation with conservative fluid management decreases mortality rates in acute respiratory distress patients, but to date there has been no investigation of the effect of conservative fluid management on VILI and ventilator associated mortality rates. We hypothesized that age-associated increases in susceptibility and incidence of pulmonary edema strongly promote age-related increases in ventilator associated mortality. Methods 2 month old and 20 month old male C57BL6 mice were mechanically ventilated with either high tidal volume (HVT) or low tidal volume (LVT) for up to 4 hours with either liberal or conservative fluid support. During ventilation, lung compliance, total lung capacity, and hysteresis curves were quantified. Following ventilation, bronchoalveolar lavage fluid was analyzed for total protein content and inflammatory cell infiltration. Wet to dry ratios were used to directly measure edema in excised lungs. Lung histology was performed to quantify alveolar barrier damage/destruction. Age matched non-ventilated mice were used as controls. Results At 4hrs, both advanced age and HVT ventilation significantly increased markers of inflammation and injury, degraded pulmonary mechanics, and decreased survival rates. Conservative fluid support significantly diminished pulmonary edema and improved pulmonary mechanics by 1hr in advanced age HVT subjects. In 4hr ventilations, conservative fluid support significantly diminished pulmonary edema, improved lung mechanics, and resulted in significantly lower mortality rates in older subjects. Conclusion Our study demonstrates that conservative fluid alone can attenuate the age associated increase in ventilator associated mortality. PMID:27188767

[Lung protective ventilation. Ventilatory modes and ventilator parameters].

PubMed

Schädler, Dirk; Weiler, Norbert

2008-06-01

Mechanical ventilation has a considerable potential for injuring the lung tissue. Therefore, attention has to be paid to the proper choice of ventilatory mode and settings to secure lung-protective ventilation whenever possible. Such ventilator strategy should account for low tidal volume ventilation (6 ml/kg PBW), limited plateau pressure (30 to 35 cm H2O) and positive end-expiratory pressure (PEEP). It is unclear whether pressure controlled or volume controlled ventilation with square flow profile is beneficial. The adjustment of inspiration and expiration time should consider the actual breathing mechanics and anticipate the generation of intrinsic PEEP. Ventilatory modes with the possibility of supporting spontaneous breathing should be used as soon as possible.

Combined Effects of Ventilation Mode and Positive End-Expiratory Pressure on Mechanics, Gas Exchange and the Epithelium in Mice with Acute Lung Injury

PubMed Central

Thammanomai, Apiradee; Hamakawa, Hiroshi; Bartolák-Suki, Erzsébet; Suki, Béla

2013-01-01

The accepted protocol to ventilate patients with acute lung injury is to use low tidal volume (VT) in combination with recruitment maneuvers or positive end-expiratory pressure (PEEP). However, an important aspect of mechanical ventilation has not been considered: the combined effects of PEEP and ventilation modes on the integrity of the epithelium. Additionally, it is implicitly assumed that the best PEEP-VT combination also protects the epithelium. We aimed to investigate the effects of ventilation mode and PEEP on respiratory mechanics, peak airway pressures and gas exchange as well as on lung surfactant and epithelial cell integrity in mice with acute lung injury. HCl-injured mice were ventilated at PEEPs of 3 and 6 cmH2O with conventional ventilation (CV), CV with intermittent large breaths (CVLB) to promote recruitment, and a new mode, variable ventilation, optimized for mice (VVN). Mechanics and gas exchange were measured during ventilation and surfactant protein (SP)-B, proSP-B and E-cadherin levels were determined from lavage and lung homogenate. PEEP had a significant effect on mechanics, gas exchange and the epithelium. The higher PEEP reduced lung collapse and improved mechanics and gas exchange but it also down regulated surfactant release and production and increased epithelial cell injury. While CVLB was better than CV, VVN outperformed CVLB in recruitment, reduced epithelial injury and, via a dynamic mechanotransduction, it also triggered increased release and production of surfactant. For long-term outcome, selection of optimal PEEP and ventilation mode may be based on balancing lung physiology with epithelial injury. PMID:23326543

Home kitchen ventilation, cooking fuels, and lung cancer risk in a prospective cohort of never smoking women in Shanghai, China.

PubMed

Kim, Christopher; Gao, Yu-Tang; Xiang, Yong-Bing; Barone-Adesi, Francesco; Zhang, Yawei; Hosgood, H Dean; Ma, Shuangge; Shu, Xiao-ou; Ji, Bu-Tian; Chow, Wong-Ho; Seow, Wei Jie; Bassig, Bryan; Cai, Qiuyin; Zheng, Wei; Rothman, Nathaniel; Lan, Qing

2015-02-01

Indoor air pollution (IAP) caused by cooking has been associated with lung cancer risk in retrospective case-control studies in developing and rural countries. We report the association of cooking conditions, fuel use, oil use, and risk of lung cancer in a developed urban population in a prospective cohort of women in Shanghai. A total of 71,320 never smoking women were followed from 1996 through 2009 and 429 incident lung cancer cases were identified. Questionnaires collected information on household living and cooking practices for the three most recent residences and utilization of cooking fuel and oil, and ventilation conditions. Cox proportional hazards regression estimated the association for kitchen ventilation conditions, cooking fuels, and use of cooking oils for the risk of lung cancer by hazard ratios (HR) with 95% confidence intervals (95% CI). Ever poor kitchen ventilation was associated with a 49% increase in lung cancer risk (HR: 1.49; 95% CI: 1.15-1.95) compared to never poor ventilation. Ever use of coal was not significantly associated. However, ever coal use with poor ventilation (HR: 1.69; 95% CI: 1.22-2.35) and 20 or more years of using coal with poor ventilation (HR: 2.03; 95% CI: 1.35-3.05) was significantly associated compared to no exposure to coal or poor ventilation. Cooking oil use was not significantly associated. These results demonstrate that IAP from poor ventilation of coal combustion increases the risk of lung cancer and is an important public health issue in cities across China where people may have lived in homes with inadequate kitchen ventilation. © 2014 UICC.

Intraoperative protective mechanical ventilation for prevention of postoperative pulmonary complications: a comprehensive review of the role of tidal volume, positive end-expiratory pressure, and lung recruitment maneuvers.

PubMed

Güldner, Andreas; Kiss, Thomas; Serpa Neto, Ary; Hemmes, Sabrine N T; Canet, Jaume; Spieth, Peter M; Rocco, Patricia R M; Schultz, Marcus J; Pelosi, Paolo; Gama de Abreu, Marcelo

2015-09-01

Postoperative pulmonary complications are associated with increased morbidity, length of hospital stay, and mortality after major surgery. Intraoperative lung-protective mechanical ventilation has the potential to reduce the incidence of postoperative pulmonary complications. This review discusses the relevant literature on definition and methods to predict the occurrence of postoperative pulmonary complication, the pathophysiology of ventilator-induced lung injury with emphasis on the noninjured lung, and protective ventilation strategies, including the respective roles of tidal volumes, positive end-expiratory pressure, and recruitment maneuvers. The authors propose an algorithm for protective intraoperative mechanical ventilation based on evidence from recent randomized controlled trials.

Substance P receptor blockade decreases stretch-induced lung cytokines and lung injury in rats.

PubMed

Brégeon, Fabienne; Steinberg, Jean Guillaume; Andreotti, Nicolas; Sabatier, Jean-Marc; Delpierre, Stéphane; Ravailhe, Sylvie; Jammes, Yves

2010-04-15

Overdistension of lung tissue during mechanical ventilation causes cytokine release, which may be facilitated by the autonomic nervous system. We used mechanical ventilation to cause lung injury in rats, and studied how cervical section of the vagus nerve, or substance P (SP) antagonism, affected the injury. The effects of 40 or 25 cmH(2)O high airway pressure injurious ventilation (HV(40) and HV(25)) were studied and compared with low airway pressure ventilation (LV) and spontaneous breathing (controls). Lung mechanics, lung weight, gas exchange, lung myeloperoxidase activity, lung concentrations of interleukin (IL)-1 beta and IL-6, and amounts of lung SP were measured. Control rats were intact, others were bivagotomized, and in some animals we administered the neurokinin-1 (NK-1) receptor blocking agent SR140333. We first determined the durations of HV(40) and HV(25) that induced the same levels of lung injury and increased lung contents of IL-1 beta and IL-6. They were 90 min and 120 min, respectively. Both HV(40) and HV(25) increased lung SP, IL-1 beta and IL-6 levels, these effects being markedly reduced by NK-1 receptor blockade. Bivagotomy reduced to a lesser extent the HV(40)- and HV(25)-induced increases in SP but significantly reduced cytokine production. Neither vagotomy nor NK-1 receptor blockade prevented HV(40)-induced lung injury but, in the HV(25) group, they made it possible to maintain lung injury indices close to those measured in the LV group. This study suggests that both neuronal and extra-neuronal SP might be involved in ventilator-induced lung inflammation and injury. NK-1 receptor blockade could be a pharmacological tool to minimize some adverse effects of mechanical ventilation.

Spatiotemporal Aeration and Lung Injury Patterns Are Influenced by the First Inflation Strategy at Birth.

PubMed

Tingay, David G; Rajapaksa, Anushi; Zonneveld, C Elroy; Black, Don; Perkins, Elizabeth J; Adler, Andy; Grychtol, Bartłomiej; Lavizzari, Anna; Frerichs, Inéz; Zahra, Valerie A; Davis, Peter G

2016-02-01

Ineffective aeration during the first inflations at birth creates regional aeration and ventilation defects, initiating injurious pathways. This study aimed to compare a sustained first inflation at birth or dynamic end-expiratory supported recruitment during tidal inflations against ventilation without intentional recruitment on gas exchange, lung mechanics, spatiotemporal regional aeration and tidal ventilation, and regional lung injury in preterm lambs. Lambs (127 ± 2 d gestation), instrumented at birth, were ventilated for 60 minutes from birth with either lung-protective positive pressure ventilation (control) or as per control after either an initial 30 seconds of 40 cm H2O sustained inflation (SI) or an initial stepwise end-expiratory pressure recruitment maneuver during tidal inflations (duration 180 s; open lung ventilation [OLV]). At study completion, molecular markers of lung injury were analyzed. The initial use of an OLV maneuver, but not SI, at birth resulted in improved lung compliance, oxygenation, end-expiratory lung volume, and reduced ventilatory needs compared with control, persisting throughout the study. These changes were due to more uniform inter- and intrasubject gravity-dependent spatiotemporal patterns of aeration (measured using electrical impedance tomography). Spatial distribution of tidal ventilation was more stable after either recruitment maneuver. All strategies caused regional lung injury patterns that mirrored associated regional volume states. Irrespective of strategy, spatiotemporal volume loss was consistently associated with up-regulation of early growth response-1 expression. Our results show that mechanical and molecular consequences of lung aeration at birth are not simply related to rapidity of fluid clearance; they are also related to spatiotemporal pressure-volume interactions within the lung during inflation and deflation.

Airways in smooth muscle α-actin null mice experience a compensatory mechanism that modulates their contractile response.

PubMed

Shardonofsky, Felix R; Moore, Joan; Schwartz, Robert J; Boriek, Aladin M

2012-03-01

We hypothesized that ablation of smooth muscle α-actin (SM α-A), a contractile-cytoskeletal protein expressed in airway smooth muscle (ASM) cells, abolishes ASM shortening capacity and decreases lung stiffness. In both SM α-A knockout and wild-type (WT) mice, airway resistance (Raw) determined by the forced oscillation technique rose in response to intravenous methacholine (Mch). However, the slope of Raw (cmH(2)O·ml(-1)·s) vs. log(2) Mch dose (μg·kg(-1)·min(-1)) was lower (P = 0.007) in mutant (0.54 ± 0.14) than in WT mice (1.23 ± 0.19). RT-PCR analysis performed on lung tissues confirmed that mutant mice lacked SM α-A mRNA and showed that these mice had robust expressions of both SM γ-A mRNA and skeletal muscle (SKM) α-A mRNA, which were not expressed in WT mice, and an enhanced SM22 mRNA expression relative to that in WT mice. Compared with corresponding spontaneously breathing mice, mechanical ventilation-induced lung mechanical strain increased the expression of SM α-A mRNA in WT lungs; in mutant mice, it augmented the expressions of SM γ-A mRNA and SM22 mRNA and did not alter that of SKM α-A mRNA. In mutant mice, the expression of SM γ-A mRNA in the lung during spontaneous breathing and its enhanced expression following mechanical ventilation are consistent with the likely possibility that in the absence of SM α-A, SM γ-A underwent polymerization and interacted with smooth muscle myosin to produce ASM shortening during cholinergic stimulation. Thus our data are consistent with ASM in mutant mice experiencing compensatory mechanisms that modulated its contractile muscle capacity.

Investigation of four-dimensional computed tomography-based pulmonary ventilation imaging in patients with emphysematous lung regions

NASA Astrophysics Data System (ADS)

Yamamoto, Tokihiro; Kabus, Sven; Klinder, Tobias; Lorenz, Cristian; von Berg, Jens; Blaffert, Thomas; Loo, Billy W., Jr.; Keall, Paul J.

2011-04-01

A pulmonary ventilation imaging technique based on four-dimensional (4D) computed tomography (CT) has advantages over existing techniques. However, physiologically accurate 4D-CT ventilation imaging has not been achieved in patients. The purpose of this study was to evaluate 4D-CT ventilation imaging by correlating ventilation with emphysema. Emphysematous lung regions are less ventilated and can be used as surrogates for low ventilation. We tested the hypothesis: 4D-CT ventilation in emphysematous lung regions is significantly lower than in non-emphysematous regions. Four-dimensional CT ventilation images were created for 12 patients with emphysematous lung regions as observed on CT, using a total of four combinations of two deformable image registration (DIR) algorithms: surface-based (DIRsur) and volumetric (DIRvol), and two metrics: Hounsfield unit (HU) change (VHU) and Jacobian determinant of deformation (VJac), yielding four ventilation image sets per patient. Emphysematous lung regions were detected by density masking. We tested our hypothesis using the one-tailed t-test. Visually, different DIR algorithms and metrics yielded spatially variant 4D-CT ventilation images. The mean ventilation values in emphysematous lung regions were consistently lower than in non-emphysematous regions for all the combinations of DIR algorithms and metrics. VHU resulted in statistically significant differences for both DIRsur (0.14 ± 0.14 versus 0.29 ± 0.16, p = 0.01) and DIRvol (0.13 ± 0.13 versus 0.27 ± 0.15, p < 0.01). However, VJac resulted in non-significant differences for both DIRsur (0.15 ± 0.07 versus 0.17 ± 0.08, p = 0.20) and DIRvol (0.17 ± 0.08 versus 0.19 ± 0.09, p = 0.30). This study demonstrated the strong correlation between the HU-based 4D-CT ventilation and emphysema, which indicates the potential for HU-based 4D-CT ventilation imaging to achieve high physiologic accuracy. A further study is needed to confirm these results.

Mechanical Ventilation in Acute Hypoxemic Respiratory Failure: A Review of New Strategies for the Practicing Hospitalist

PubMed Central

Wilson, Jennifer G.; Matthay, Michael A.

2014-01-01

BACKGROUND The goal of mechanical ventilation in acute hypoxemic respiratory failure is to support adequate gas exchange without harming the lungs. How patients are mechanically ventilated can significantly impact their ultimate outcomes. METHODS This review focuses on emerging evidence regarding strategies for mechanical ventilation in patients with acute hypoxemic respiratory failure including: low tidal volume ventilation in the acute respiratory distress syndrome (ARDS), novel ventilator modes as alternatives to low tidal volume ventilation, adjunctive strategies that may enhance recovery in ARDS, the use of lung-protective strategies in patients without ARDS, rescue therapies in refractory hypoxemia, and an evidence-based approach to weaning from mechanical ventilation. RESULTS Once a patient is intubated and mechanically ventilated, low tidal volume ventilation remains the best strategy in ARDS. Adjunctive therapies in ARDS include a conservative fluid management strategy, as well as neuromuscular blockade and prone positioning in moderate-to-severe disease. There is also emerging evidence that a lung-protective strategy may benefit non-ARDS patients. For patients with refractory hypoxemia, extracorporeal membrane oxygenation should be considered. Once the patient demonstrates signs of recovery, the best approach to liberation from mechanical ventilation involves daily spontaneous breathing trials and protocolized assessment of readiness for extubation. CONCLUSIONS Prompt recognition of ARDS and use of lung-protective ventilation, as well as evidence-based adjunctive therapies, remain the cornerstones of caring for patients with acute hypoxemic respiratory failure. In the absence of contraindications, it is reasonable to consider lung-protective ventilation in non-ARDS patients as well, though the evidence supporting this practice is less conclusive. PMID:24733692

High tidal volume ventilation induces NOS2 and impairs cAMP- dependent air space fluid clearance.

PubMed

Frank, James A; Pittet, Jean-Francois; Lee, Hyon; Godzich, Micaela; Matthay, Michael A

2003-05-01

Tidal volume reduction during mechanical ventilation reduces mortality in patients with acute lung injury and the acute respiratory distress syndrome. To determine the mechanisms underlying the protective effect of low tidal volume ventilation, we studied the time course and reversibility of ventilator-induced changes in permeability and distal air space edema fluid clearance in a rat model of ventilator-induced lung injury. Anesthetized rats were ventilated with a high tidal volume (30 ml/kg) or with a high tidal volume followed by ventilation with a low tidal volume of 6 ml/kg. Endothelial and epithelial protein permeability were significantly increased after high tidal volume ventilation but returned to baseline levels when tidal volume was reduced. The basal distal air space fluid clearance (AFC) rate decreased by 43% (P < 0.05) after 1 h of high tidal volume but returned to the preventilation rate 2 h after tidal volume was reduced. Not all of the effects of high tidal volume ventilation were reversible. The cAMP-dependent AFC rate after 1 h of 30 ml/kg ventilation was significantly reduced and was not restored when tidal volume was reduced. High tidal volume ventilation also increased lung inducible nitric oxide synthase (NOS2) expression and air space total nitrite at 3 h. Inhibition of NOS2 activity preserved cAMP-dependent AFC. Because air space edema fluid inactivates surfactant and reduces ventilated lung volume, the reduction of cAMP-dependent AFC by reactive nitrogen species may be an important mechanism of clinical ventilator-associated lung injury.

Mitogen-activated protein kinase phosphatase-1 modulates regional effects of injurious mechanical ventilation in rodent lungs.

PubMed

Park, Moo Suk; He, Qianbin; Edwards, Michael G; Sergew, Amen; Riches, David W H; Albert, Richard K; Douglas, Ivor S

2012-07-01

Mechanical ventilation induces heterogeneous lung injury by mitogen-activated protein kinase (MAPK) and nuclear factor-κB. Mechanisms regulating regional injury and protective effects of prone positioning are unclear. To determine the key regulators of the lung regional protective effects of prone positioning in rodent lungs exposed to injurious ventilation. Adult rats were ventilated with high (18 ml/kg, positive end-expiratory pressure [PEEP] 0) or low Vt (6 ml/kg; PEEP 3 cm H(2)O; 3 h) in supine or prone position. Dorsal-caudal lung mRNA was analyzed by microarray and MAPK phosphatases (MKP)-1 quantitative polymerase chain reaction. MKP-1(-/-) or wild-type mice were ventilated with very high (24 ml/kg; PEEP 0) or low Vt (6-7 ml/kg; PEEP 3 cm H(2)O). The MKP-1 regulator PG490-88 (MRx-108; 0.75 mg/kg) or phosphate-buffered saline was administered preventilation. Injury was assessed by lung mechanics, bronchioalveolar lavage cell counts, protein content, and lung injury scoring. Immunoblotting for MKP-1, and IκBα and cytokine ELISAs were performed on lung lysates. Prone positioning was protective against injurious ventilation in rats. Expression profiling demonstrated MKP-1 20-fold higher in rats ventilated prone rather than supine and regional reduction in p38 and c-jun N-terminal kinase activation. MKP-1(-/-) mice experienced amplified injury. PG490-88 improved static lung compliance and injury scores, reduced bronchioalveolar lavage cell counts and cytokine levels, and induced MKP-1 and IκBα. Injurious ventilation induces MAPK in an MKP-1-dependent fashion. Prone positioning is protective and induces MKP-1. PG490-88 induced MKP-1 and was protective against high Vt in a nuclear factor-κB-dependent manner. MKP-1 is a potential target for modulating regional effects of injurious ventilation.

Mild hypothermia attenuates changes in respiratory system mechanics and modifies cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation.

PubMed

Dostál, P; Senkeřík, M; Pařízková, R; Bareš, D; Zivný, P; Zivná, H; Cerný, V

2010-01-01

Hypothermia was shown to attenuate ventilator-induced lung injury due to large tidal volumes. It is unclear if the protective effect of hypothermia is maintained under less injurious mechanical ventilation in animals without previous lung injury. Tracheostomized rats were randomly allocated to non-ventilated group (group C) or ventilated groups of normothermia (group N) and mild hypothermia (group H). After two hours of mechanical ventilation with inspiratory fraction of oxygen 1.0, respiratory rate 60 min(-1), tidal volume 10 ml x kg(-1), positive end-expiratory pressure (PEEP) 2 cm H2O or immediately after tracheostomy in non-ventilated animals inspiratory pressures were recorded, rats were sacrificed, pressure-volume (PV) curve of respiratory system constructed, bronchoalveolar lavage (BAL) fluid and aortic blood samples obtained. Group N animals exhibited a higher rise in peak inspiratory pressures in comparison to group H animals. Shift of the PV curve to right, higher total protein and interleukin-6 levels in BAL fluid were observed in normothermia animals in comparison with hypothermia animals and non-ventilated controls. Tumor necrosis factor-alpha was lower in the hypothermia group in comparison with normothermia and non-ventilated groups. Mild hypothermia attenuated changes in respiratory system mechanics and modified cytokine concentration in bronchoalveolar lavage fluid during low lung volume ventilation in animals without previous lung injury.

[Lung protective ventilation - pathophysiology and diagnostics].

PubMed

Uhlig, Stefan; Frerichs, Inéz

2008-06-01

Mechanical ventilation may lead to lung injury depending on the ventilatory settings (e.g. pressure amplitudes, endexpiratory pressures, frequency) and the length of mechanical ventilation. Particularly in the inhomogeneously injured lungs of ARDS patients, alveolar overextension results in volutrauma, cyclic opening and closure of alveolar units in atelectrauma. Particularly important appears to be the fact that these processes may also cause biotrauma, i.e. the ventilator-induced hyperactivation of inflammatory responses in the lung. These side effects are reduced, but not eliminated with the currently recommended ventilation strategy with a tidal volume of 6 ml/kg idealized body weight. It is our hope that in the future optimization of ventilator settings will be facilated by bedside monitoring of novel indices of respiratory mechanics such as the stress index or the Slice technique, and by innovative real-time imaging technologies such as electrical impedance tomography.

Mechanical stress induces lung fibrosis by epithelial-mesenchymal transition.

PubMed

Cabrera-Benítez, Nuria E; Parotto, Matteo; Post, Martin; Han, Bing; Spieth, Peter M; Cheng, Wei-Erh; Valladares, Francisco; Villar, Jesús; Liu, Mingayo; Sato, Masaaki; Zhang, Haibo; Slutsky, Arthur S

2012-02-01

Many mechanically ventilated patients with acute respiratory distress syndrome develop pulmonary fibrosis. Stresses induced by mechanical ventilation may explain the development of fibrosis by a number of mechanisms (e.g., damage the alveolar epithelium, biotrauma). The objective of this study was t test the hypothesis that mechanical ventilation plays an important role in the pathogenesis of lung fibrosis. C57BL/6 mice were randomized into four groups: healthy controls; hydrochloric acid aspiration alone; vehicle control solution followed 24 hrs later by mechanical ventilation (peak inspiratory pressure 22 cm H(2)O and positive end-expiratory pressure 2 cm H(2)O for 2 hrs); and acid aspiration followed 24 hrs later by mechanical ventilation. The animals were monitored for up to 15 days after acid aspiration. To explore the direct effects of mechanical stress on lung fibrotic formation, human lung epithelial cells (BEAS-2B) were exposed to mechanical stretch for up to 48 hrs. Impaired lung mechanics after mechanical ventilation was associated with increased lung hydroxyproline content, and increased expression of transforming growth factor-β, β-catenin, and mesenchymal markers (α-smooth muscle actin and vimentin) at both the gene and protein levels. Expression of epithelial markers including cytokeratin-8, E-cadherin, and prosurfactant protein B decreased. Lung histology demonstrated fibrosis formation and potential epithelia-mesenchymal transition. In vitro direct mechanical stretch of BEAS-2B cells resulted in similar fibrotic and epithelia-mesenchymal transition formation. Mechanical stress induces lung fibrosis, and epithelia-mesenchymal transition may play an important role in mediating the ventilator-induced lung fibrosis.

Mechanical ventilation with lower tidal volumes and positive end-expiratory pressure prevents pulmonary inflammation in patients without preexisting lung injury.

PubMed

Wolthuis, Esther K; Choi, Goda; Dessing, Mark C; Bresser, Paul; Lutter, Rene; Dzoljic, Misa; van der Poll, Tom; Vroom, Margreeth B; Hollmann, Markus; Schultz, Marcus J

2008-01-01

Mechanical ventilation with high tidal volumes aggravates lung injury in patients with acute lung injury or acute respiratory distress syndrome. The authors sought to determine the effects of short-term mechanical ventilation on local inflammatory responses in patients without preexisting lung injury. Patients scheduled to undergo an elective surgical procedure (lasting > or = 5 h) were randomly assigned to mechanical ventilation with either higher tidal volumes of 12 ml/kg ideal body weight and no positive end-expiratory pressure (PEEP) or lower tidal volumes of 6 ml/kg and 10 cm H2O PEEP. After induction of anesthesia and 5 h thereafter, bronchoalveolar lavage fluid and/or blood was investigated for polymorphonuclear cell influx, changes in levels of inflammatory markers, and nucleosomes. Mechanical ventilation with lower tidal volumes and PEEP (n = 21) attenuated the increase of pulmonary levels of interleukin (IL)-8, myeloperoxidase, and elastase as seen with higher tidal volumes and no PEEP (n = 19). Only for myeloperoxidase, a difference was found between the two ventilation strategies after 5 h of mechanical ventilation (P < 0.01). Levels of tumor necrosis factor alpha, IL-1alpha, IL-1beta, IL-6, macrophage inflammatory protein 1alpha, and macrophage inflammatory protein 1beta in the bronchoalveolar lavage fluid were not affected by mechanical ventilation. Plasma levels of IL-6 and IL-8 increased with mechanical ventilation, but there were no differences between the two ventilation groups. The use of lower tidal volumes and PEEP may limit pulmonary inflammation in mechanically ventilated patients without preexisting lung injury. The specific contribution of both lower tidal volumes and PEEP on the protective effects of the lung should be further investigated.

[Treatment of acute respiratory distress syndrome using pressure and volume controlled ventilation with lung protective strategy].

PubMed

Ge, Ying; Wan, Yong; Wang, Da-qing; Su, Xiao-lin; Li, Jun-ying; Chen, Jing

2004-07-01

To investigate the significance and effect of pressure controlled ventilation (PCV) as well as volume controlled ventilation (VCV) by lung protective strategy on respiratory mechanics, blood gas analysis and hemodynamics in patients with acute respiratory distress syndrome (ARDS). Fifty patients with ARDS were randomly divided into PCV and VCV groups with permissive hypercapnia and open lung strategy. Changes in respiratory mechanics, blood gas analysis and hemodynamics were compared between two groups. Peak inspiration pressure (PIP) in PCV group was significantly lower than that in VCV group, while mean pressure of airway (MPaw) was significantly higher than that in VCV after 24 hours mechanical ventilation. After 24 hours mechanical ventilation, there were higher central venous pressure (CVP) and slower heart rate (HR) in two groups, CVP was significantly higher in VCV compared with PCV, and PCV group had slower HR than VCV group, the two groups had no differences in mean blood pressure (MBP) at various intervals. All patients showed no ventilator-induced lung injury. Arterial blood oxygenations were obviously improved in two groups after 24 hours mechanical ventilation, PCV group had better partial pressure of oxygen in artery (PaO2) than VCV group. Both PCV and VCV can improve arterial blood oxygenations, prevent ventilator-induced lung injury, and have less disturbance in hemodynamic parameters. PCV with lung protective ventilatory strategy should be early use for patients with ARDS.

[USE OF PROTECTIVE LUNG VENTILATION REGIMEN IN CARDIAC SURGERY PATIENTS.

PubMed

Pshenichniy, T A; Akselrod, B A; Titova, I V; Trekova, N A; Khrustaleva, M V

2017-09-01

In cardiac surgery, protective lung ventilation and/or preventive brdnchoscopy (PB) are able to decrease lung injury effects of cardiopulmonary bypass (CPB) and mechanical ventilation. define lung complication risks, evaluate the effect ofprotective lung ventilation (PLV) on lung functioning, and investigate the feasibility ofpreventive PB in higher pulmonary risk (PR) patients. 66 patients participated in prospective randomized research. Allocation was based on PR and intraoperative mechanical ventilation type. PLV includedfollowing parameters: PCK PIP - up to 20 cm H20, Vt - 6 ml/ kg of PBW, PEEP - 5-10 cm H20, IE ratio - 1:1.5-1:1, EtCO2 - 35-42 mm Hg, FiO2 - 45-60%, lung ventilation during CPB, alveolar recruitment. Four groups were formed: A - higher PR plus PLV- B - higher PR plus conventional LV (CLV), C - lower PR plus PLV- D - lower PR plus CLV PIP PEEP dynamic compliance, p/f ratio and intrapulmonary shunt (Qs/Qt) were recorded. Seventeen patients of group A underwent PB. Advanced dynamic compliance, higher p/f ratio and lower Qs/Qt were seen in group A, in comparison with group B (p< 0.05). Lower Qs/Qt was seen in group C, in comparison with group D (p<0.05). Mucus obstruction of subsegmental bronchi was observed in 53.3% of higher PR patients. More than half ofpatients without PB sufferedfrom postoperative lung complications (70.4 vs. 34.2 7%, p

Increase in pulmonary blood flow at birth: role of oxygen and lung aeration.

PubMed

Lang, Justin A R; Pearson, James T; Binder-Heschl, Corinna; Wallace, Megan J; Siew, Melissa L; Kitchen, Marcus J; te Pas, Arjan B; Fouras, Andreas; Lewis, Robert A; Polglase, Graeme R; Shirai, Mikiyasu; Hooper, Stuart B

2016-03-01

Lung aeration stimulates the increase in pulmonary blood flow (PBF) at birth, but the spatial relationships between PBF and lung aeration and the role of increased oxygenation remain unclear. Using simultaneous phase-contrast X-ray imaging and angiography, we have investigated the separate roles of lung aeration and increased oxygenation in PBF changes at birth using near-term (30 days of gestation) rabbit kits (n = 18). Rabbits were imaged before ventilation, then the right lung was ventilated with 100% nitrogen (N2), air or 100% O2 (oxygen), before all kits were switched to ventilation in air, followed by ventilation of both lungs using air. Unilateral ventilation of the right lung with 100% N2 significantly increased heart rate (from 69.4 ± 4.9 to 93.0 ± 15.0 bpm), the diameters of both left and right pulmonary axial arteries, number of visible vessels in both left and right lungs, relative PBF index in both pulmonary arteries, and reduced bolus transit time for both left and right axial arteries (from 1.34 ± 0.39 and 1.81 ± 0.43 s to 0.52 ± 0.17 and 0.89 ± 0.21 s in the left and right axial arteries, respectively). Similar changes were observed with 100% oxygen, but increases in visible vessel number and vessel diameter of the axial arteries were greater in the ventilated right lung during unilateral ventilation. These findings confirm that PBF increase at birth is not spatially related to lung aeration and that the increase in PBF to unventilated regions is unrelated to oxygenation, although oxygen can potentiate this increase. © 2015 The Authors. The Journal of Physiology © 2015 The Physiological Society.

Limiting ventilator-induced lung injury through individual electronic medical record surveillance.

PubMed

Herasevich, Vitaly; Tsapenko, Mykola; Kojicic, Marija; Ahmed, Adil; Kashyap, Rachul; Venkata, Chakradhar; Shahjehan, Khurram; Thakur, Sweta J; Pickering, Brian W; Zhang, Jiajie; Hubmayr, Rolf D; Gajic, Ognjen

2011-01-01

To improve the safety of ventilator care and decrease the risk of ventilator-induced lung injury, we designed and tested an electronic algorithm that incorporates patient characteristics and ventilator settings, allowing near-real-time notification of bedside providers about potentially injurious ventilator settings. Electronic medical records of consecutive patients who received invasive ventilation were screened in three Mayo Clinic Rochester intensive care units. The computer system alerted bedside providers via the text paging notification about potentially injurious ventilator settings. Alert criteria included a Pao2/Fio2 ratio of <300 mm Hg, free text search for the words "edema" or "bilateral + infiltrates" on the chest radiograph report, a tidal volume of >8 mL/kg predicted body weight (based on patient gender and height), a plateau pressure of >30 cm H2O, and a peak airway pressure of >35 cm H2O. Respiratory therapists answered a brief online satisfaction survey. Ventilator-induced lung injury risk was compared before and after the introduction of ventilator-induced lung injury alert. The prevalence of acute lung injury was 42% (n = 490) among 1,159 patients receiving >24 hrs of invasive ventilation. The system sent 111 alerts for 80 patients, with a positive predictive value of 59%. The exposure to potentially injurious ventilation decreased after the intervention from 40.6 ± 74.6 hrs to 26.9 ± 77.3 hrs (p = .004). Electronic medical record surveillance of mechanically ventilated patients accurately detects potentially injurious ventilator settings and is able to influence bedside practice at moderate costs. Its implementation is associated with decreased patient exposure to potentially injurious mechanical ventilation settings.

Accelerated deflation promotes homogeneous airspace liquid distribution in the edematous lung.

PubMed

Wu, You; Nguyen, Tam L; Perlman, Carrie E

2017-04-01

Edematous lungs contain regions with heterogeneous alveolar flooding. Liquid is trapped in flooded alveoli by a pressure barrier-higher liquid pressure at the border than in the center of flooded alveoli-that is proportional to surface tension, T Stress is concentrated between aerated and flooded alveoli, to a degree proportional to T Mechanical ventilation, by cyclically increasing T , injuriously exacerbates stress concentrations. Overcoming the pressure barrier to redistribute liquid more homogeneously between alveoli should reduce stress concentration prevalence and ventilation injury. In isolated rat lungs, we test whether accelerated deflation can overcome the pressure barrier and catapult liquid out of flooded alveoli. We generate a local edema model with normal T by microinfusing liquid into surface alveoli. We generate a global edema model with high T by establishing hydrostatic edema, which does not alter T , and then gently ventilating the edematous lungs, which increases T at 15 cmH 2 O transpulmonary pressure by 52%. Thus ventilation of globally edematous lungs increases T , which should increase stress concentrations and, with positive feedback, cause escalating ventilation injury. In the local model, when the pressure barrier is moderate, accelerated deflation causes liquid to escape from flooded alveoli and redistribute more equitably. Flooding heterogeneity tends to decrease. In the global model, accelerated deflation causes liquid escape, but-because of elevated T -the liquid jumps to nearby, aerated alveoli. Flooding heterogeneity is unaltered. In pulmonary edema with normal T , early ventilation with accelerated deflation might reduce the positive feedback mechanism through which ventilation injury increases over time. NEW & NOTEWORTHY We introduce, in the isolated rat lung, a new model of pulmonary edema with elevated surface tension. We first generate hydrostatic edema and then ventilate gently to increase surface tension. We investigate the mechanical mechanisms through which 1 ) ventilation injures edematous lungs and 2 ) ventilation with accelerated deflation might lessen ventilation injury. Copyright © 2017 the American Physiological Society.

Accelerated deflation promotes homogeneous airspace liquid distribution in the edematous lung

PubMed Central

Wu, You; Nguyen, Tam L.

2017-01-01

Edematous lungs contain regions with heterogeneous alveolar flooding. Liquid is trapped in flooded alveoli by a pressure barrier—higher liquid pressure at the border than in the center of flooded alveoli—that is proportional to surface tension, T. Stress is concentrated between aerated and flooded alveoli, to a degree proportional to T. Mechanical ventilation, by cyclically increasing T, injuriously exacerbates stress concentrations. Overcoming the pressure barrier to redistribute liquid more homogeneously between alveoli should reduce stress concentration prevalence and ventilation injury. In isolated rat lungs, we test whether accelerated deflation can overcome the pressure barrier and catapult liquid out of flooded alveoli. We generate a local edema model with normal T by microinfusing liquid into surface alveoli. We generate a global edema model with high T by establishing hydrostatic edema, which does not alter T, and then gently ventilating the edematous lungs, which increases T at 15 cmH2O transpulmonary pressure by 52%. Thus ventilation of globally edematous lungs increases T, which should increase stress concentrations and, with positive feedback, cause escalating ventilation injury. In the local model, when the pressure barrier is moderate, accelerated deflation causes liquid to escape from flooded alveoli and redistribute more equitably. Flooding heterogeneity tends to decrease. In the global model, accelerated deflation causes liquid escape, but—because of elevated T—the liquid jumps to nearby, aerated alveoli. Flooding heterogeneity is unaltered. In pulmonary edema with normal T, early ventilation with accelerated deflation might reduce the positive feedback mechanism through which ventilation injury increases over time. NEW & NOTEWORTHY We introduce, in the isolated rat lung, a new model of pulmonary edema with elevated surface tension. We first generate hydrostatic edema and then ventilate gently to increase surface tension. We investigate the mechanical mechanisms through which 1) ventilation injures edematous lungs and 2) ventilation with accelerated deflation might lessen ventilation injury. PMID:27979983

Electrical impedance tomography compared to positron emission tomography for the measurement of regional lung ventilation: an experimental study

PubMed Central

Richard, JC; Pouzot, C; Gros, A; Tourevieille, C; Lebars, D; Lavenne, F; Frerichs, I; Guérin, C

2009-01-01

Introduction Electrical impedance tomography (EIT), which can assess regional lung ventilation at the bedside, has never been compared with positron-emission tomography (PET), a gold-standard to quantify regional ventilation. This experiment systematically compared both techniques in injured and non-injured lungs. Methods The study was performed in six mechanically ventilated female piglets. In normal lungs, tidal volume (VT) was randomly changed to 6, 8, 10 and 15 ml/kg on zero end-expiratory pressure (ZEEP), then, at VT 10 ml/kg, positive end-expiratory pressure (PEEP) was randomly changed to 5, 10 and 15 cmH2O. Afterwards, acute lung injury (ALI) was subsequently created in three animals by injecting 3 ml/kg hydrochloric acid into the trachea. Then at PEEP 5 cmH2O, VT was randomly changed to 8 and 12 ml/kg and PEEP of 10 and 15 cmH2O applied at VT 10 ml/kg. EIT and PET examinations were performed simultaneously. EIT ventilation (VTEIT) and lung volume (VL) were measured in the anterior and posterior area of each lung. On the same regions of interest, ventilation (VPET) and aerated lung volume (VAatten) were determined with PET. Results On ZEEP, VTEIT and VPET significantly correlated for global (VTEIT = VPET - 2E-13, R2 = 0.95, P < 0.001) and regional (VTEIT = 0.81VPET+7.65, R2 = 0.63, P < 0.001) ventilation over both conditions. For ALI condition, corresponding R2 were 0.91 and 0.73 (P < 0.01). Bias was = 0 and limits of agreement were -37.42 and +37.42 ml/min for global ventilation over both conditions. These values were 0.04 and -29.01 and +29.08 ml/min, respectively, for regional ventilation. Significant correlations were also found between VL and VAatten for global (VL = VAatten+1E-12, R2 = 0.93, P < 0.0001) and regional (VL = 0.99VAatten+0.92, R2 = 0.65, P < 0.001) volume. For ALI condition, corresponding R2 were 0.94 (P < 0.001) and 0.54 (P < 0.05). Bias was = 0 and limits of agreement ranged -38.16 and +38.16 ml for global ventilation over both conditions. These values were -0.24 and -31.96 to +31.48 ml, respectively, for regional ventilation. Conclusions Regional lung ventilation and volume were accurately measured with EIT in healthy and injured lungs and validated by simultaneous PET imaging. PMID:19480694

When does the lung die? Kfc, cell viability, and adenine nucleotide changes in the circulation-arrested rat lung.

PubMed

Jones, D R; Becker, R M; Hoffmann, S C; Lemasters, J J; Egan, T M

1997-07-01

Lungs harvested from cadaveric circulation-arrested donors may increase the donor pool for lung transplantation. To determine the degree and time course of ischemia-reperfusion injury, we evaluated the effect of O2 ventilation on capillary permeability [capillary filtration coefficient (Kfc)], cell viability, and total adenine nucleotide (TAN) levels in in situ circulation-arrested rat lungs. Kfc increased with increasing postmortem ischemic time (r = 0.88). Lungs ventilated with O2 1 h postmortem had similar Kfc and wet-to-dry ratios as controls. Nonventilated lungs had threefold (P < 0.05) and sevenfold (P < 0.0001) increases in Kfc at 30 and 60 min postmortem compared with controls. Cell viability decreased in all groups except for 30-min postmortem O2-ventilated lungs. TAN levels decreased with increasing ischemic time, particularly in nonventilated lungs. Loss of adenine nucleotides correlated with increasing Kfc values (r = 0.76). This study indicates that lungs retrieved 1 h postmortem may have normal Kfc with preharvest O2 ventilation. The relationship between Kfc and TAN suggests that vascular permeability may be related to lung TAN levels.

Household ventilation may reduce effects of indoor air pollutants for prevention of lung cancer: a case-control study in a Chinese population.

PubMed

Jin, Zi-Yi; Wu, Ming; Han, Ren-Qiang; Zhang, Xiao-Feng; Wang, Xu-Shan; Liu, Ai-Ming; Zhou, Jin-Yi; Lu, Qing-Yi; Kim, Claire H; Mu, Lina; Zhang, Zuo-Feng; Zhao, Jin-Kou

2014-01-01

Although the International Agency for Research on Cancer (IARC) has classified various indoor air pollutants as carcinogenic to humans, few studies evaluated the role of household ventilation in reducing the impact of indoor air pollutants on lung cancer risk. To explore the association between household ventilation and lung cancer. A population-based case-control study was conducted in a Chinese population from 2003 to 2010. Epidemiologic and household ventilation data were collected using a standardized questionnaire. Unconditional logistic regression was employed to estimate adjusted odds ratios (ORadj) and their 95% confidence intervals (CI). Among 1,424 lung cancer cases and 4,543 healthy controls, inverse associations were observed for good ventilation in the kitchen (ORadj = 0.86, 95% CI: 0.75, 0.98), bedroom (ORadj = 0.90, 95% CI: 0.79, 1.03), and both kitchen and bedroom (ORadj = 0.87, 95% CI: 0.75, 1.00). Stratified analyses showed lung cancer inversely associated with good ventilation among active smokers (ORadj = 0.85, 95% CI: 0.72, 1.00), secondhand smokers at home (ORadj = 0.77, 95% CI: 0.63, 0.94), and those exposed to high-temperature cooking oil fumes (ORadj = 0.82, 95% CI: 0.68, 0.99). Additive interactions were found between household ventilation and secondhand smoke at home as well as number of household pollutant sources. A protective association was observed between good ventilation of households and lung cancer, most likely through the reduction of exposure to indoor air pollutants, indicating ventilation may serve as one of the preventive measures for lung cancer, in addition to tobacco cessation.

Home kitchen ventilation, cooking fuels, and lung cancer risk in a prospective cohort of never smoking women in Shanghai, China

PubMed Central

Kim, Christopher; Gao, Yu-Tang; Xiang, Yong-Bing; Barone-Adesi, Francesco; Zhang, Yawei; Hosgood, H. Dean; Ma, Shuangge; Shu, Xiao-ou; Ji, Bu-Tian; Chow, Wong-Ho; Seow, Wei Jie; Bassig, Bryan; Cai, Qiuyin; Zheng, Wei; Rothman, Nathaniel; Lan, Qing

2014-01-01

Indoor air pollution (IAP) caused by cooking has been associated with lung cancer risk in retrospective case-control studies in developing and rural countries. We report the association of cooking conditions, fuel use, oil use and risk of lung cancer in a developed urban population in a prospective cohort of women in Shanghai. A total of 71,320 never smoking women were followed from 1996 through 2009 and 429 incident lung cancer cases were identified. Questionnaires collected information on household living and cooking practices for the women’s three most recent residences and utilization of cooking fuel and oil, and ventilation conditions. Cox proportional hazards regression estimated the association for kitchen ventilation conditions, cooking fuels, and use of cooking oils for the risk of lung cancer by hazard ratios (HR) with 95% confidence intervals (95% CI). Ever poor kitchen ventilation was associated with a 49% increase in lung cancer risk (HR: 1.49; 95% CI: 1.15–1.95) compared to never poor ventilation. Ever use of coal was not significantly associated. However, ever coal use with poor ventilation (HR: 1.69; 95% CI: 1.22–2.35) and twenty or more years of using coal (HR: 2.03; 95% CI: 1.35–3.05) was significantly associated compared to no exposure to coal or poor ventilation. Cooking oil use was not significantly associated. These results demonstrate that IAP from poor ventilation of coal combustion increases the risk of lung cancer and is an important public health issue in cities across China where people may have lived in homes with inadequate kitchen ventilation. PMID:24917360

Effect of lung-protective ventilation with lower tidal volumes on clinical outcomes among patients undergoing surgery: a meta-analysis of randomized controlled trials.

PubMed

Gu, Wan-Jie; Wang, Fei; Liu, Jing-Chen

2015-02-17

In anesthetized patients undergoing surgery, the role of lung-protective ventilation with lower tidal volumes is unclear. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the effect of this ventilation strategy on postoperative outcomes. We searched electronic databases from inception through September 2014. We included RCTs that compared protective ventilation with lower tidal volumes and conventional ventilation with higher tidal volumes in anesthetized adults undergoing surgery. We pooled outcomes using a random-effects model. The primary outcome measures were lung injury and pulmonary infection. We included 19 trials (n=1348). Compared with patients in the control group, those who received lung-protective ventilation had a decreased risk of lung injury (risk ratio [RR] 0.36, 95% confidence interval [CI] 0.17 to 0.78; I2=0%) and pulmonary infection (RR 0.46, 95% CI 0.26 to 0.83; I2=8%), and higher levels of arterial partial pressure of carbon dioxide (standardized mean difference 0.47, 95% CI 0.18 to 0.75; I2=65%). No significant differences were observed between the patient groups in atelectasis, mortality, length of hospital stay, length of stay in the intensive care unit or the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen. Anesthetized patients who received ventilation with lower tidal volumes during surgery had a lower risk of lung injury and pulmonary infection than those given conventional ventilation with higher tidal volumes. Implementation of a lung-protective ventilation strategy with lower tidal volumes may lower the incidence of these outcomes. © 2015 Canadian Medical Association or its licensors.

Sphingolipids in Congenital Diaphragmatic Hernia; Results from an International Multicenter Study

PubMed Central

Snoek, Kitty G.; Reiss, Irwin K. M.; Tibboel, Jeroen; van Rosmalen, Joost; Capolupo, Irma; van Heijst, Arno; Schaible, Thomas; Post, Martin; Tibboel, Dick

2016-01-01

Background Congenital diaphragmatic hernia is a severe congenital anomaly with significant mortality and morbidity, for instance chronic lung disease. Sphingolipids have shown to be involved in lung injury, but their role in the pathophysiology of chronic lung disease has not been explored. We hypothesized that sphingolipid profiles in tracheal aspirates could play a role in predicting the mortality/ development of chronic lung disease in congenital diaphragmatic hernia patients. Furthermore, we hypothesized that sphingolipid profiles differ between ventilation modes; conventional mechanical ventilation versus high-frequency oscillation. Methods Sphingolipid levels in tracheal aspirates were determined at days 1, 3, 7 and 14 in 72 neonates with congenital diaphragmatic hernia, born after > 34 weeks gestation at four high-volume congenital diaphragmatic hernia centers. Data were collected within a multicenter trial of initial ventilation strategy (NTR 1310). Results 36 patients (50.0%) died or developed chronic lung disease, 34 patients (47.2%) by stratification were initially ventilated by conventional mechanical ventilation and 38 patients (52.8%) by high-frequency oscillation. Multivariable logistic regression analysis with correction for side of the defect, liver position and observed-to-expected lung-to-head ratio, showed that none of the changes in sphingolipid levels were significantly associated with mortality /development of chronic lung disease. At day 14, long-chain ceramides 18:1 and 24:0 were significantly elevated in patients initially ventilated by conventional mechanical ventilation compared to high-frequency oscillation. Conclusions We could not detect significant differences in temporal sphingolipid levels in congenital diaphragmatic hernia infants with mortality/development of chronic lung disease versus survivors without development of CLD. Elevated levels of ceramides 18:1 and 24:0 in the conventional mechanical ventilation group when compared to high-frequency oscillation could probably be explained by high peak inspiratory pressures and remodeling of the alveolar membrane. PMID:27159222

The Use of High-Frequency Percussive Ventilation for Whole-Lung Lavage: A Case Report.

PubMed

Kinthala, Sudhakar; Liang, Mark; Khusid, Felix; Harrison, Sebron

2018-04-23

Whole-lung lavage (WLL) remains the gold standard in the treatment of pulmonary alveolar proteinosis. However, anesthetic management during WLL can be challenging because of the risk of intraoperative hypoxemia and various cardiorespiratory complications of 1-lung ventilation. Here, we describe a novel strategy involving the application of high-frequency percussive ventilation using a volumetric diffusive respirator (VDR-4) during WLL in a 47-year-old woman with pulmonary alveolar proteinosis. Our observations suggest that high-frequency percussive ventilation is a potentially effective ventilation strategy during WLL that may reduce the risk of hypoxemia and facilitate lavage.

Mechanical ventilation-associated lung fibrosis in acute respiratory distress syndrome: a significant contributor to poor outcome.

PubMed

Cabrera-Benitez, Nuria E; Laffey, John G; Parotto, Matteo; Spieth, Peter M; Villar, Jesús; Zhang, Haibo; Slutsky, Arthur S

2014-07-01

One of the most challenging problems in critical care medicine is the management of patients with the acute respiratory distress syndrome. Increasing evidence from experimental and clinical studies suggests that mechanical ventilation, which is necessary for life support in patients with acute respiratory distress syndrome, can cause lung fibrosis, which may significantly contribute to morbidity and mortality. The role of mechanical stress as an inciting factor for lung fibrosis versus its role in lung homeostasis and the restoration of normal pulmonary parenchymal architecture is poorly understood. In this review, the authors explore recent advances in the field of pulmonary fibrosis in the context of acute respiratory distress syndrome, concentrating on its relevance to the practice of mechanical ventilation, as commonly applied by anesthetists and intensivists. The authors focus the discussion on the thesis that mechanical ventilation-or more specifically, that ventilator-induced lung injury-may be a major contributor to lung fibrosis. The authors critically appraise possible mechanisms underlying the mechanical stress-induced lung fibrosis and highlight potential therapeutic strategies to mitigate this fibrosis.

Detection of early subclinical lung disease in children with cystic fibrosis by lung ventilation imaging with hyperpolarised gas MRI.

PubMed

Marshall, Helen; Horsley, Alex; Taylor, Chris J; Smith, Laurie; Hughes, David; Horn, Felix C; Swift, Andrew J; Parra-Robles, Juan; Hughes, Paul J; Norquay, Graham; Stewart, Neil J; Collier, Guilhem J; Teare, Dawn; Cunningham, Steve; Aldag, Ina; Wild, Jim M

2017-08-01

Hyperpolarised 3 He ventilation-MRI, anatomical lung MRI, lung clearance index (LCI), low-dose CT and spirometry were performed on 19 children (6-16 years) with clinically stable mild cystic fibrosis (CF) (FEV 1 >-1.96), and 10 controls. All controls had normal spirometry, MRI and LCI. Ventilation-MRI was the most sensitive method of detecting abnormalities, present in 89% of patients with CF, compared with CT abnormalities in 68%, LCI 47% and conventional MRI 22%. Ventilation defects were present in the absence of CT abnormalities and in patients with normal physiology, including LCI. Ventilation-MRI is thus feasible in young children, highly sensitive and provides additional information about lung structure-function relationships. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Scintigraphy at 3 months after single lung transplantation and observations of primary graft dysfunction and lung function.

PubMed

Belmaati, Esther Okeke; Iversen, Martin; Kofoed, Klaus F; Nielsen, Michael B; Mortensen, Jann

2012-06-01

Scintigraphy has been used as a tool to detect dysfunction of the lung before and after transplantation. The aims of this study were to evaluate the development of the ventilation-perfusion relationships in single lung transplant recipients in the first year, at 3 months after transplantation, and to investigate whether scintigraphic findings at 3 months were predictive for the outcome at 12 months in relation to primary graft dysfunction (PGD) and lung function. A retrospective study was carried out on all patients who prospectively and consecutively were referred for a routine lung scintigraphy procedure 3 months after single lung transplantation (SLTX). A total of 41 patients were included in the study: 20 women and 21 men with the age span of patients at transplantation being 38-66 years (mean ± SD: 54.2 ± 6.0). Patient records also included lung function tests and chest X-ray images. We found no significant correlation between lung function distribution at 3 months and PGD at 72 h. There was also no significant correlation between PGD scores at 72 h and lung function at 6 and 12 months. The same applied to scintigraphic scores for heterogeneity at 3 months compared with lung function at 6 and 12 months. Fifty-five percent of all patients had decreased ventilation function measured in the period from 6 to 12 months. Forty-nine percent of the patients had normal perfusion evaluations, and 51% had abnormal perfusion evaluations at 3 months. For ventilation evaluations, 72% were normal and 28% were abnormal. There was a significant difference in the normal versus abnormal perfusion and ventilation scintigraphic images evaluated from the same patients. Ventilation was distributed more homogenously in the transplanted lung than perfusion in the same lung. The relative distribution of perfusion and ventilation to the transplanted lung of patients with and without a primary diagnosis of fibrosis did not differ significantly from each other. We conclude that PGD defined at 72 h does not lead to recognizable changes in ventilation-perfusion scintigrapy at 3 months, and scintigraphic findings do not correlate with development in lung function in the first 12 months.

High-performance C-arm cone-beam CT guidance of thoracic surgery

NASA Astrophysics Data System (ADS)

Schafer, Sebastian; Otake, Yoshito; Uneri, Ali; Mirota, Daniel J.; Nithiananthan, Sajendra; Stayman, J. W.; Zbijewski, Wojciech; Kleinszig, Gerhard; Graumann, Rainer; Sussman, Marc; Siewerdsen, Jeffrey H.

2012-02-01

Localizing sub-palpable nodules in minimally invasive video-assisted thoracic surgery (VATS) presents a significant challenge. To overcome inherent problems of preoperative nodule tagging using CT fluoroscopic guidance, an intraoperative C-arm cone-beam CT (CBCT) image-guidance system has been developed for direct localization of subpalpable tumors in the OR, including real-time tracking of surgical tools (including thoracoscope), and video-CBCT registration for augmentation of the thoracoscopic scene. Acquisition protocols for nodule visibility in the inflated and deflated lung were delineated in phantom and animal/cadaver studies. Motion compensated reconstruction was implemented to account for motion induced by the ventilated contralateral lung. Experience in CBCT-guided targeting of simulated lung nodules included phantoms, porcine models, and cadavers. Phantom studies defined low-dose acquisition protocols providing contrast-to-noise ratio sufficient for lung nodule visualization, confirmed in porcine specimens with simulated nodules (3-6mm diameter PE spheres, ~100-150HU contrast, 2.1mGy). Nodule visibility in CBCT of the collapsed lung, with reduced contrast according to air volume retention, was more challenging, but initial studies confirmed visibility using scan protocols at slightly increased dose (~4.6-11.1mGy). Motion compensated reconstruction employing a 4D deformation map in the backprojection process reduced artifacts associated with motion blur. Augmentation of thoracoscopic video with renderings of the target and critical structures (e.g., pulmonary artery) showed geometric accuracy consistent with camera calibration and the tracking system (2.4mm registration error). Initial results suggest a potentially valuable role for CBCT guidance in VATS, improving precision in minimally invasive, lungconserving surgeries, avoid critical structures, obviate the burdens of preoperative localization, and improve patient safety.

Comparative Effects of Volutrauma and Atelectrauma on Lung Inflammation in Experimental Acute Respiratory Distress Syndrome

PubMed Central

Güldner, Andreas; Braune, Anja; Ball, Lorenzo; Silva, Pedro L.; Samary, Cynthia; Insorsi, Angelo; Huhle, Robert; Rentzsch, Ines; Becker, Claudia; Oehme, Liane; Andreeff, Michael; Vidal Melo, Marcos F.; Winkler, Tilo; Pelosi, Paolo; Rocco, Patricia R. M.; Kotzerke, Jörg; de Abreu, Marcelo Gama

2016-01-01

Objective Volutrauma and atelectrauma promote ventilator-induced lung injury, but their relative contribution to inflammation in ventilator-induced lung injury is not well established. The aim of this study was to determine the impact of volutrauma and atelectrauma on the distribution of lung inflammation in experimental acute respiratory distress syndrome. Design Laboratory investigation. Setting University-hospital research facility. Subjects Ten pigs (five per group; 34.7–49.9 kg) Interventions Animals were anesthetized and intubated, and saline lung lavage was performed. Lungs were separated with a double-lumen tube. Following lung recruitment and decremental positive end-expiratory pressure trial, animals were randomly assigned to 4 hours of ventilation of the left (ventilator-induced lung injury) lung with tidal volume of approximately 3 mL/kg and 1) high positive end-expiratory pressure set above the level where dynamic compliance increased more than 5% during positive end-expiratory pressure trial (volutrauma); or 2) low positive end-expiratory pressure to achieve driving pressure comparable with volutrauma (atelectrauma). The right (control) lung was kept on continuous positive airway pressure of 20 cm H2O, and Co2 was partially removed extracorporeally. Measurements and Main Results Regional lung aeration, specific [18F]fluorodeoxyglucose uptake rate, and perfusion were assessed using computed and positron emission tomography. Volutrauma yielded higher [18F]fluorodeoxyglucose uptake rate in the ventilated lung compared with atelectrauma (median [interquartile range], 0.017 [0.014–0.025] vs 0.013 min−1 [0.010–0.014min−1]; p < 0.01), mainly in central lung regions. Volutrauma yielded higher [18F]fluorodeoxyglucose uptake rate in ventilator-induced lung injury versus control lung (0.017 [0.014–0.025] vs 0.011 min−1 [0.010–0.016min−1]; p < 0.05), whereas atelectrauma did not. Volutrauma decreased blood fraction at similar perfusion and increased normally as well as hyper-aerated lung compartments and tidal hyperaeration. Atelectrauma yielded higher poorly and nonaerated lung compartments, and tidal recruitment. Driving pressure increased in atelectrauma. Conclusions In this model of acute respiratory distress syndrome, volutrauma promoted higher lung inflammation than atelectrauma at comparable low tidal volume and lower driving pressure, suggesting that static stress and strain are major determinants of ventilator-induced lung injury. PMID:27035236

Liquid ventilation.

PubMed

Sarkar, Suman; Paswan, Anil; Prakas, S

2014-01-01

Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.

Mechanical ventilation drives pneumococcal pneumonia into lung injury and sepsis in mice: protection by adrenomedullin.

PubMed

Müller-Redetzky, Holger C; Will, Daniel; Hellwig, Katharina; Kummer, Wolfgang; Tschernig, Thomas; Pfeil, Uwe; Paddenberg, Renate; Menger, Michael D; Kershaw, Olivia; Gruber, Achim D; Weissmann, Norbert; Hippenstiel, Stefan; Suttorp, Norbert; Witzenrath, Martin

2014-04-14

Ventilator-induced lung injury (VILI) contributes to morbidity and mortality in acute respiratory distress syndrome (ARDS). Particularly pre-injured lungs are susceptible to VILI despite protective ventilation. In a previous study, the endogenous peptide adrenomedullin (AM) protected murine lungs from VILI. We hypothesized that mechanical ventilation (MV) contributes to lung injury and sepsis in pneumonia, and that AM may reduce lung injury and multiple organ failure in ventilated mice with pneumococcal pneumonia. We analyzed in mice the impact of MV in established pneumonia on lung injury, inflammation, bacterial burden, hemodynamics and extrapulmonary organ injury, and assessed the therapeutic potential of AM by starting treatment at intubation. In pneumococcal pneumonia, MV increased lung permeability, and worsened lung mechanics and oxygenation failure. MV dramatically increased lung and blood cytokines but not lung leukocyte counts in pneumonia. MV induced systemic leukocytopenia and liver, gut and kidney injury in mice with pneumonia. Lung and blood bacterial burden was not affected by MV pneumonia and MV increased lung AM expression, whereas receptor activity modifying protein (RAMP) 1-3 expression was increased in pneumonia and reduced by MV. Infusion of AM protected against MV-induced lung injury (66% reduction of pulmonary permeability p < 0.01; prevention of pulmonary restriction) and against VILI-induced liver and gut injury in pneumonia (91% reduction of AST levels p < 0.05, 96% reduction of alanine aminotransaminase (ALT) levels p < 0.05, abrogation of histopathological changes and parenchymal apoptosis in liver and gut). MV paved the way for the progression of pneumonia towards ARDS and sepsis by aggravating lung injury and systemic hyperinflammation leading to liver, kidney and gut injury. AM may be a promising therapeutic option to protect against development of lung injury, sepsis and extrapulmonary organ injury in mechanically ventilated individuals with severe pneumonia.

Increasing the inspiratory time and I:E ratio during mechanical ventilation aggravates ventilator-induced lung injury in mice.

PubMed

Müller-Redetzky, Holger C; Felten, Matthias; Hellwig, Katharina; Wienhold, Sandra-Maria; Naujoks, Jan; Opitz, Bastian; Kershaw, Olivia; Gruber, Achim D; Suttorp, Norbert; Witzenrath, Martin

2015-01-28

Lung-protective ventilation reduced acute respiratory distress syndrome (ARDS) mortality. To minimize ventilator-induced lung injury (VILI), tidal volume is limited, high plateau pressures are avoided, and positive end-expiratory pressure (PEEP) is applied. However, the impact of specific ventilatory patterns on VILI is not well defined. Increasing inspiratory time and thereby the inspiratory/expiratory ratio (I:E ratio) may improve oxygenation, but may also be harmful as the absolute stress and strain over time increase. We thus hypothesized that increasing inspiratory time and I:E ratio aggravates VILI. VILI was induced in mice by high tidal-volume ventilation (HVT 34 ml/kg). Low tidal-volume ventilation (LVT 9 ml/kg) was used in control groups. PEEP was set to 2 cm H2O, FiO2 was 0.5 in all groups. HVT and LVT mice were ventilated with either I:E of 1:2 (LVT 1:2, HVT 1:2) or 1:1 (LVT 1:1, HVT 1:1) for 4 hours or until an alternative end point, defined as mean arterial blood pressure below 40 mm Hg. Dynamic hyperinflation due to the increased I:E ratio was excluded in a separate group of animals. Survival, lung compliance, oxygenation, pulmonary permeability, markers of pulmonary and systemic inflammation (leukocyte differentiation in lung and blood, analyses of pulmonary interleukin-6, interleukin-1β, keratinocyte-derived chemokine, monocyte chemoattractant protein-1), and histopathologic pulmonary changes were analyzed. LVT 1:2 or LVT 1:1 did not result in VILI, and all individuals survived the ventilation period. HVT 1:2 decreased lung compliance, increased pulmonary neutrophils and cytokine expression, and evoked marked histologic signs of lung injury. All animals survived. HVT 1:1 caused further significant worsening of oxygenation, compliance and increased pulmonary proinflammatory cytokine expression, and pulmonary and blood neutrophils. In the HVT 1:1 group, significant mortality during mechanical ventilation was observed. According to the "baby lung" concept, mechanical ventilation-associated stress and strain in overinflated regions of ARDS lungs was simulated by using high tidal-volume ventilation. Increase of inspiratory time and I:E ratio significantly aggravated VILI in mice, suggesting an impact of a "stress/strain × time product" for the pathogenesis of VILI. Thus increasing the inspiratory time and I:E ratio should be critically considered.

Injurious mechanical ventilation in the normal lung causes a progressive pathologic change in dynamic alveolar mechanics.

PubMed

Pavone, Lucio A; Albert, Scott; Carney, David; Gatto, Louis A; Halter, Jeffrey M; Nieman, Gary F

2007-01-01

Acute respiratory distress syndrome causes a heterogeneous lung injury, and without protective mechanical ventilation a secondary ventilator-induced lung injury can occur. To ventilate noncompliant lung regions, high inflation pressures are required to 'pop open' the injured alveoli. The temporal impact, however, of these elevated pressures on normal alveolar mechanics (that is, the dynamic change in alveolar size and shape during ventilation) is unknown. In the present study we found that ventilating the normal lung with high peak pressure (45 cmH(2)0) and low positive end-expiratory pressure (PEEP of 3 cmH(2)O) did not initially result in altered alveolar mechanics, but alveolar instability developed over time. Anesthetized rats underwent tracheostomy, were placed on pressure control ventilation, and underwent sternotomy. Rats were then assigned to one of three ventilation strategies: control group (n = 3, P control = 14 cmH(2)O, PEEP = 3 cmH(2)O), high pressure/low PEEP group (n = 6, P control = 45 cmH(2)O, PEEP = 3 cmH(2)O), and high pressure/high PEEP group (n = 5, P control = 45 cmH(2)O, PEEP = 10 cmH(2)O). In vivo microscopic footage of subpleural alveolar stability (that is, recruitment/derecruitment) was taken at baseline and than every 15 minutes for 90 minutes following ventilator adjustments. Alveolar recruitment/derecruitment was determined by measuring the area of individual alveoli at peak inspiration (I) and end expiration (E) by computer image analysis. Alveolar recruitment/derecruitment was quantified by the percentage change in alveolar area during tidal ventilation (%I - E Delta). Alveoli were stable in the control group for the entire experiment (low %I - E Delta). Alveoli in the high pressure/low PEEP group were initially stable (low %I - E Delta), but with time alveolar recruitment/derecruitment developed. The development of alveolar instability in the high pressure/low PEEP group was associated with histologic lung injury. A large change in lung volume with each breath will, in time, lead to unstable alveoli and pulmonary damage. Reducing the change in lung volume by increasing the PEEP, even with high inflation pressure, prevents alveolar instability and reduces injury. We speculate that ventilation with large changes in lung volume over time results in surfactant deactivation, which leads to alveolar instability.

An experimental study on the impacts of inspiratory and expiratory muscles activities during mechanical ventilation in ARDS animal model

PubMed Central

Zhang, Xianming; Du, Juan; Wu, Weiliang; Zhu, Yongcheng; Jiang, Ying; Chen, Rongchang

2017-01-01

In spite of intensive investigations, the role of spontaneous breathing (SB) activity in ARDS has not been well defined yet and little has been known about the different contribution of inspiratory or expiratory muscles activities during mechanical ventilation in patients with ARDS. In present study, oleic acid-induced beagle dogs’ ARDS models were employed and ventilated with the same level of mean airway pressure. Respiratory mechanics, lung volume, gas exchange and inflammatory cytokines were measured during mechanical ventilation, and lung injury was determined histologically. As a result, for the comparable ventilator setting, preserved inspiratory muscles activity groups resulted in higher end-expiratory lung volume (EELV) and oxygenation index. In addition, less lung damage scores and lower levels of system inflammatory cytokines were revealed after 8 h of ventilation. In comparison, preserved expiratory muscles activity groups resulted in lower EELV and oxygenation index. Moreover, higher lung injury scores and inflammatory cytokines levels were observed after 8 h of ventilation. Our findings suggest that the activity of inspiratory muscles has beneficial effects, whereas that of expiratory muscles exerts adverse effects during mechanical ventilation in ARDS animal model. Therefore, for mechanically ventilated patients with ARDS, the demands for deep sedation or paralysis might be replaced by the strategy of expiratory muscles paralysis through epidural anesthesia. PMID:28230150

Inhibition of HMGCoA reductase by simvastatin protects mice from injurious mechanical ventilation.

PubMed

Manitsopoulos, Nikolaos; Orfanos, Stylianos E; Kotanidou, Anastasia; Nikitopoulou, Ioanna; Siempos, Ilias; Magkou, Christina; Dimopoulou, Ioanna; Zakynthinos, Spyros G; Armaganidis, Apostolos; Maniatis, Nikolaos A

2015-02-14

Mortality from severe acute respiratory distress syndrome exceeds 40% and there is no available pharmacologic treatment. Mechanical ventilation contributes to lung dysfunction and mortality by causing ventilator-induced lung injury. We explored the utility of simvastatin in a mouse model of severe ventilator-induced lung injury. Male C57BL6 mice (n = 7/group) were pretreated with simvastatin or saline and received protective (8 mL/kg) or injurious (25 mL/kg) ventilation for four hours. Three doses of simvastatin (20 mg/kg) or saline were injected intraperitoneally on days -2, -1 and 0 of the experiment. Lung mechanics, (respiratory system elastance, tissue damping and airway resistance), were evaluated by forced oscillation technique, while respiratory system compliance was measured with quasi-static pressure-volume curves. A pathologist blinded to treatment allocation scored hematoxylin-eosin-stained lung sections for the presence of lung injury. Pulmonary endothelial dysfunction was ascertained by bronchoalveolar lavage protein content and lung tissue expression of endothelial junctional protein Vascular Endothelial cadherin by immunoblotting. To assess the inflammatory response in the lung, we determined bronchoalveolar lavage fluid total cell content and neutrophil fraction by microscopy and staining in addition to Matrix-Metalloprotease-9 by ELISA. For the systemic response, we obtained plasma levels of Tumor Necrosis Factor-α, Interleukin-6 and Matrix-Metalloprotease-9 by ELISA. Statistical hypothesis testing was undertaken using one-way analysis of variance and Tukey's post hoc tests. Ventilation with high tidal volume (HVt) resulted in significantly increased lung elastance by 3-fold and decreased lung compliance by 45% compared to low tidal volume (LVt) but simvastatin abrogated lung mechanical alterations of HVt. Histologic lung injury score increased four-fold by HVt but not in simvastatin-pretreated mice. Lavage pleocytosis and neutrophilia were induced by HVt but were significantly attenuated by simvastatin. Microvascular protein permeability increase 20-fold by injurious ventilation but only 4-fold with simvastatin. There was a 3-fold increase in plasma Tumor Necrosis Factor-α, a 7-fold increase in plasma Interleukin-6 and a 20-fold increase in lavage fluid Matrix-Metalloprotease-9 by HVt but simvastatin reduced these levels to control. Lung tissue vascular endothelial cadherin expression was significantly reduced by injurious ventilation but remained preserved by simvastatin. High-dose simvastatin prevents experimental hyperinflation lung injury by angioprotective and anti-inflammatory effects.

Epithelial and endothelial damage induced by mechanical ventilation modes.

PubMed

Suki, Béla; Hubmayr, Rolf

2014-02-01

The adult respiratory distress syndrome (ARDS) is a common cause of respiratory failure with substantial impact on public health. Patients with ARDS generally require mechanical ventilation, which risks further lung damage. Recent improvements in ARDS outcomes have been attributed to reductions in deforming stress associated with lung protective mechanical ventilation modes and settings. The following review details the mechanics of the lung parenchyma at different spatial scales and the response of its resident cells to deforming stress in order to provide the biologic underpinnings of lung protective care. Although lung injury is typically viewed through the lens of altered barrier properties and mechanical ventilation-associated immune responses, in this review, we call attention to the importance of heterogeneity and the physical failure of the load bearing cell and tissue elements in the pathogenesis of ARDS. Specifically, we introduce a simple elastic network model to better understand the deformations of lung regions, intra-acinar alveoli and cells within a single alveolus, and consider the role of regional distension and interfacial stress-related injury for various ventilation modes. Heterogeneity of stiffness and intercellular and intracellular stress failure are fundamental components of ARDS and their development also depends on the ventilation mode.

Mechanical ventilation interacts with endotoxemia to induce extrapulmonary organ dysfunction

PubMed Central

O'Mahony, D Shane; Liles, W Conrad; Altemeier, William A; Dhanireddy, Shireesha; Frevert, Charles W; Liggitt, Denny; Martin, Thomas R; Matute-Bello, Gustavo

2006-01-01

Introduction Multiple organ dysfunction syndrome (MODS) is a common complication of sepsis in mechanically ventilated patients with acute respiratory distress syndrome, but the links between mechanical ventilation and MODS are unclear. Our goal was to determine whether a minimally injurious mechanical ventilation strategy synergizes with low-dose endotoxemia to induce the activation of pro-inflammatory pathways in the lungs and in the systemic circulation, resulting in distal organ dysfunction and/or injury. Methods We administered intraperitoneal Escherichia coli lipopolysaccharide (LPS; 1 μg/g) to C57BL/6 mice, and 14 hours later subjected the mice to 6 hours of mechanical ventilation with tidal volumes of 10 ml/kg (LPS + MV). Comparison groups received ventilation but no LPS (MV), LPS but no ventilation (LPS), or neither LPS nor ventilation (phosphate-buffered saline; PBS). Results Myeloperoxidase activity and the concentrations of the chemokines macrophage inflammatory protein-2 (MIP-2) and KC were significantly increased in the lungs of mice in the LPS + MV group, in comparison with mice in the PBS group. Interestingly, permeability changes across the alveolar epithelium and histological changes suggestive of lung injury were minimal in mice in the LPS + MV group. However, despite the minimal lung injury, the combination of mechanical ventilation and LPS resulted in chemical and histological evidence of liver and kidney injury, and this was associated with increases in the plasma concentrations of KC, MIP-2, IL-6, and TNF-α. Conclusion Non-injurious mechanical ventilation strategies interact with endotoxemia in mice to enhance pro-inflammatory mechanisms in the lungs and promote extra-pulmonary end-organ injury, even in the absence of demonstrable acute lung injury. PMID:16995930

Effects of tidal volume on work of breathing during lung-protective ventilation in patients with acute lung injury and acute respiratory distress syndrome.

PubMed

Kallet, Richard H; Campbell, Andre R; Dicker, Rochelle A; Katz, Jeffrey A; Mackersie, Robert C

2006-01-01

To assess the effects of step-changes in tidal volume on work of breathing during lung-protective ventilation in patients with acute lung injury (ALI) or the acute respiratory distress syndrome (ARDS). Prospective, nonconsecutive patients with ALI/ARDS. Adult surgical, trauma, and medical intensive care units at a major inner-city, university-affiliated hospital. Ten patients with ALI/ARDS managed clinically with lung-protective ventilation. Five patients were ventilated at a progressively smaller tidal volume in 1 mL/kg steps between 8 and 5 mL/kg; five other patients were ventilated at a progressively larger tidal volume from 5 to 8 mL/kg. The volume mode was used with a flow rate of 75 L/min. Minute ventilation was maintained constant at each tidal volume setting. Afterward, patients were placed on continuous positive airway pressure for 1-2 mins to measure their spontaneous tidal volume. Work of breathing and other variables were measured with a pulmonary mechanics monitor (Bicore CP-100). Work of breathing progressively increased (0.86 +/- 0.32, 1.05 +/- 0.40, 1.22 +/- 0.36, and 1.57 +/- 0.43 J/L) at a tidal volume of 8, 7, 6, and 5 mL/kg, respectively. In nine of ten patients there was a strong negative correlation between work of breathing and the ventilator-to-patient tidal volume difference (R = -.75 to -.998). : The ventilator-delivered tidal volume exerts an independent influence on work of breathing during lung-protective ventilation in patients with ALI/ARDS. Patient work of breathing is inversely related to the difference between the ventilator-delivered tidal volume and patient-generated tidal volume during a brief trial of unassisted breathing.

Low Tidal Volume Ventilation in Patients without Acute Respiratory Distress Syndrome: A Paradigm Shift in Mechanical Ventilation

PubMed Central

Lipes, Jed; Bojmehrani, Azadeh; Lellouche, Francois

2012-01-01

Protective ventilation with low tidal volume has been shown to reduce morbidity and mortality in patients suffering from acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Low tidal volume ventilation is associated with particular clinical challenges and is therefore often underutilized as a therapeutic option in clinical practice. Despite some potential difficulties, data have been published examining the application of protective ventilation in patients without lung injury. We will briefly review the physiologic rationale for low tidal volume ventilation and explore the current evidence for protective ventilation in patients without lung injury. In addition, we will explore some of the potential reasons for its underuse and provide strategies to overcome some of the associated clinical challenges. PMID:22536499

Radiostethoscopes: an innovative solution for auscultation while wearing protective gear.

PubMed

Candiotti, Keith A; Rodriguez, Yiliam; Curia, Luciana; Saltzman, Bruce; Shekhter, Ilya; Rosen, Lisa; Birnbach, David J

2011-01-01

To demonstrate a radiostethoscope that could be modified and successfully used while wearing protective gear to solve the problem of auscultation in a hazardous material or infectious disease setting. This study was a randomized, prospective, and blinded investigation. The study was conducted at the University of Miami-Jackson Memorial Hospital Center for Patient Safety. Two blinded anesthesiologists using a radiostethoscope performed a total of 100 assessments (50 each) to evaluate endotracheal tube position on a human patient simulator (HPS). Each lung of the HPS was ventilated separately using a double lumen tube. Four ventilation patterns (ie, right lung ventilation only; left lung ventilation only; ventilation of both lungs; and an esophageal intubation or no breath sounds) were simulated. The ventilation pattern was determined randomly and participants were blinded. An Ambu-Bag was used for ventilation. An assistant moved the radiostethoscope to the right and left lung fields and then to the abdomen of the HPS while ventilating. Subjects had to identify the ventilation pattern after listening to all three locations. A third member of the research team collected responses. Each subject, who wore both types of respirator (positive and negative), performed a total of 25 trials. Participants later compared the two types of respirators and their ability to auscultate for breath sounds. Subjects were able to verify the correct ventilation pattern in all attempts (100 percent). Radiostethoscopes appear to provide a viable solution for the problem of patient auscultation while wearing protective gear.

Mathematics of Ventilator-induced Lung Injury.

PubMed

Rahaman, Ubaidur

2017-08-01

Ventilator-induced lung injury (VILI) results from mechanical disruption of blood-gas barrier and consequent edema and releases of inflammatory mediators. A transpulmonary pressure (P L ) of 17 cmH 2 O increases baby lung volume to its anatomical limit, predisposing to VILI. Viscoelastic property of lung makes pulmonary mechanics time dependent so that stress (P L ) increases with respiratory rate. Alveolar inhomogeneity in acute respiratory distress syndrome acts as a stress riser, multiplying global stress at regional level experienced by baby lung. Limitation of stress (P L ) rather than strain (tidal volume [V T ]) is the safe strategy of mechanical ventilation to prevent VILI. Driving pressure is the noninvasive surrogate of lung strain, but its relations to P L is dependent on the chest wall compliance. Determinants of lung stress (V T , driving pressure, positive end-expiratory pressure, and inspiratory flow) can be quantified in terms of mechanical power, and a safe threshold can be determined, which can be used in decision-making between safe mechanical ventilation and extracorporeal lung support.

The effects of intraoperative lung protective ventilation with positive end-expiratory pressure on blood loss during hepatic resection surgery: A secondary analysis of data from a published randomised control trial (IMPROVE).

PubMed

Neuschwander, Arthur; Futier, Emmanuel; Jaber, Samir; Pereira, Bruno; Eurin, Mathilde; Marret, Emmanuel; Szymkewicz, Olga; Beaussier, Marc; Paugam-Burtz, Catherine

2016-04-01

During high-risk abdominal surgery the use of a multi-faceted lung protective ventilation strategy composed of low tidal volumes, positive end-expiratory pressure (PEEP) and recruitment manoeuvres, has been shown to improve clinical outcomes. It has been speculated, however, that mechanical ventilation using PEEP might increase intraoperative bleeding during liver resection. To study the impact of mechanical ventilation with PEEP on bleeding during hepatectomy. Post-hoc analysis of a randomised controlled trial. Seven French university teaching hospitals from January 2011 to August 2012. Patients scheduled for liver resection surgery. In the Intraoperative Protective Ventilation trial, patients scheduled for major abdominal surgery were randomly assigned to mechanical ventilation using low tidal volume, PEEP between 6 and 8  cmH2O and recruitment manoeuvres (lung protective ventilation strategy) or higher tidal volume, zero PEEP and no recruitment manoeuvres (non-protective ventilation strategy). The primary endpoint was intraoperative blood loss volume. A total of 79 (19.8%) patients underwent liver resections (41 in the lung protective and 38 in the non-protective group). The median (interquartile range) amount of intraoperative blood loss was 500 (200 to 800)  ml and 275 (125 to 800)  ml in the non-protective and lung protective ventilation groups, respectively (P = 0.47). Fourteen (35.0%) and eight (21.5%) patients were transfused in the non-protective and lung protective groups, respectively (P = 0.17), without a statistically significant difference in the median (interquartile range) number of red blood cells units transfused [2.5 (2 to 4) units and 3 (2 to 6) units in the two groups, respectively; P = 0.54]. During hepatic surgery, mechanical ventilation using PEEP within a multi-faceted lung protective strategy was not associated with increased bleeding compared with non-protective ventilation using zero PEEP. The current study was not registered. The original Intraoperative Protective Ventilation study was registered on clinicaltrials.gov; number NCT01282996.

WE-AB-202-03: Quantifying Ventilation Change Due to Radiation Therapy Using 4DCT Jacobian Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patton, T; Du, K; Bayouth, J

Purpose: Four-dimensional computed tomography (4DCT) and image registration can be used to determine regional lung ventilation changes after radiation therapy (RT). This study aimed to determine if lung ventilation change following radiation therapy was affected by the pre-RT ventilation of the lung. Methods: 13 subjects had three 4DCT scans: two repeat scans acquired before RT and one three months after RT. Regional ventilation was computed using Jacobian determinant calculations on the registered 4DCT images. The post-RT ventilation map was divided by the pre-RT ventilation map to get a voxel-by-voxel Jacobian ratio map depicting ventilation change over the course of RT.more » Jacobian ratio change was compared over the range of delivered doses. The first pre-RT ventilation image was divided by the second to establish a control for Jacobian ratio change without radiation delivered. The functional change between scans was assessed using histograms of the Jacobian ratios. Results: There were significantly (p < 0.05) more voxels that had a large decrease in Jacobian ratio in the post-RT divided by pre-RT map (15.6%) than the control (13.2%). There were also significantly (p < .01) more voxels that had a large increase in Jacobian ratio (16.2%) when compared to control (13.3%). Lung regions with low function (<10% expansion by Jacobian) showed a slight linear reduction in expansion (0.2%/10 Gy delivered), while high function regions (>10% expansion) showed a greater response (1.2% reduction/10 Gy). Contiguous high function regions > 1 liter occurred in 11 of 13 subjects. Conclusion: There is a significant change in regional ventilation following a course of radiation therapy. The change in Jacobian following RT is dependent both on the delivered dose and the initial ventilation of the lung tissue: high functioning lung has greater ventilation loss for equivalent radiation doses. Substantial regions of high function lung tissue are prevalent. Research support from NIH grants CA166119 and CA166703, a gift from Roger Koch, and a Pilot Grant from University of Iowa Carver College of Medicine.« less

Lung-protective mechanical ventilation does not protect against acute kidney injury in patients without lung injury at onset of mechanical ventilation.

PubMed

Cortjens, Bart; Royakkers, Annick A N M; Determann, Rogier M; van Suijlen, Jeroen D E; Kamphuis, Stephan S; Foppen, Jannetje; de Boer, Anita; Wieland, Cathrien W; Spronk, Peter E; Schultz, Marcus J; Bouman, Catherine S C

2012-06-01

Preclinical and clinical studies suggest that mechanical ventilation contributes to the development of acute kidney injury (AKI), particularly in the setting of lung-injurious ventilator strategies. To determine whether ventilator settings in critically ill patients without acute lung injury (ALI) at onset of mechanical ventilation affect the development of AKI. Secondary analysis of a randomized controlled trial (N = 150), comparing conventional tidal volume (V(T), 10 mL/kg) with low tidal volume (V(T), 6 mL/kg) mechanical ventilation in critically ill patients without ALI at randomization. During the first 5 days of mechanical ventilation, the RIFLE class was determined daily, whereas neutrophil gelatinase-associated lipocalin and cystatin C levels were measured in plasma collected on days 0, 2, and 4. Eighty-six patients had no AKI at inclusion, and 18 patients (21%) subsequently developed AKI, but without significant difference between ventilation strategies. (Cumulative hazard, 0.26 vs 0.23; P = .88.) The courses of neutrophil gelatinase-associated lipocalin and cystatin C plasma levels did not differ significantly between randomization groups. In the present study in critically patients without ALI at onset of mechanical ventilation, lower tidal volume ventilation did not reduce the development or worsening of AKI compared with conventional tidal volume ventilation. Copyright © 2012 Elsevier Inc. All rights reserved.

Postmortem and ex vivo carbon monoxide ventilation reduces injury in rat lungs transplanted from non-heart-beating donors.

PubMed

Dong, Boming; Stewart, Paul W; Egan, Thomas M

2013-08-01

We sought to determine whether ventilation of lungs after death in non-heart-beating donors with carbon monoxide during warm ischemia and ex vivo lung perfusion and after transplant would reduce ischemia-reperfusion injury and improve lung function. One hour after death, Sprague-Dawley rats were ventilated for another hour with 60% oxygen (control group) or 500 ppm carbon monoxide in 60% oxygen (CO-vent group; n=6/group). Then, lungs were flushed with 20 mL cold Perfadex, stored cold for 1 hour, then warmed to 37 °C in an ex vivo lung perfusion circuit perfused with Steen solution. At 37 °C, lungs were ventilated for 15 minutes with alveolar gas with or without 500 ppm carbon monoxide, then perfusion-cooled to 20 °C, flushed with cold Perfadex and stored cold for 2 hours. The left lung was transplanted using a modified cuff technique. Recipients were ventilated with 60% oxygen with or without carbon monoxide. One hour after transplant, we measured blood gases from the left pulmonary vein and aorta, and wet-to-dry ratio of both lungs. The RNA and protein extracted from graft lungs underwent real-time polymerase chain reaction and Western blotting, and measurement of cyclic guanosine monophosphate by enzyme-linked immunosorbent assay. Carbon monoxide ventilation begun 1 hour after death reduced wet/dry ratio after ex vivo lung perfusion. After transplantation, the carbon monoxide-ventilation group had better oxygenation; higher levels of tissue cyclic guanosine monophosphate, heme oxidase-1 expression, and p38 phosphorylation; reduced c-Jun N-terminal kinase phosphorylation; and reduced expression of interleukin-6 and interleukin-1β messenger RNA. Administration of carbon monoxide to the deceased donor and non-heart-beating donor lungs reduces ischemia-reperfusion injury in rat lungs transplanted from non-heart-beating donors. Therapy to the deceased donor via the airway may improve post-transplant lung function. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Airway Pressure Release Ventilation During Ex Vivo Lung Perfusion Attenuates Injury

PubMed Central

Mehaffey, J. Hunter; Charles, Eric J.; Sharma, Ashish K.; Money, Dustin; Zhao, Yunge; Stoler, Mark H; Lau, Christine L; Tribble, Curtis G.; Laubach, Victor E.; Roeser, Mark E.; Kron, Irving L.

2016-01-01

Objective Critical organ shortages have resulted in Ex Vivo Lung Perfusion (EVLP) gaining clinical acceptance for lung evaluation and rehabilitation to expand the use of Donation after Circulatory Death (DCD) organs for lung transplantation. We hypothesized that an innovative use of airway pressure release ventilation (APRV) during EVLP improves lung function after transplantation. Methods Two groups (n=4 animals/group) of porcine DCD donor lungs were procured after hypoxic cardiac arrest and a 2-hour period of warm ischemia, followed by a 4-hour period of EVLP rehabilitation with either standard conventional volume-based ventilation or pressure-based APRV. Left lungs were subsequently transplanted into recipient animals and reperfused for 4 hours. Blood gases for PaO2/FiO2 ratios, airway pressures for calculation of compliance, and percent wet weight gain during EVLP and reperfusion were measured. Results APRV during EVLP significantly improved left-lung oxygenation at 2-hours (561.5±83.9 vs 341.1±136.1 mmHg) and 4-hours (569.1±18.3 vs 463.5±78.4 mmHg). Similarly, compliance was significantly higher at 2-hours (26.0±5.2 vs 15.0±4.6 mL/cmH2O) and 4-hours (30.6±1.3 vs 17.7±5.9 mL/cmH2O) after transplantation. Finally, APRV significantly reduced lung edema development on EVLP based on percentage weight gain (36.9±14.6 vs 73.9±4.9%). There was no difference in additional edema accumulation 4 hours after reperfusion. Conclusions Pressure-directed APRV ventilation strategy during EVLP improves rehabilitation of severely injured DCD lungs. After transplant these lungs demonstrate superior lung-specific oxygenation and dynamic compliance compared to lungs ventilated with standard conventional ventilation. This strategy, if implemented into clinical EVLP protocols, could advance the field of DCD lung rehabilitation to expand the lung donor pool. PMID:27742245

Partial liquid ventilation reduces fluid filtration of isolated rabbit lungs with acute hydrochloric acid-induced edema.

PubMed

Loer, S A; Tarnow, J

2001-06-01

Hydrochloric acid aspiration increases pulmonary microvascular permeability. The authors tested the hypothesis that partial liquid ventilation has a beneficial effect on filtration coefficients in acute acid-induced lung injury. Isolated blood-perfused rabbit lungs were assigned randomly to one of four groups. Group 1 (n = 6) served as a control group without edema. In group 2 (n = 6), group 3 (n = 6), and group 4 (n = 6), pulmonary edema was induced by intratracheal instillation of hydrochloric acid (0.1 N, 2 ml/kg body weight). Filtration coefficients were determined 30 min after this injury (by measuring loss of perfusate after increase of left atrial pressure). Group 2 lungs were gas ventilated, and group 3 lungs received partial liquid ventilation (15 ml perfluorocarbon/kg body weight). In group 4 lungs, the authors studied the immediate effects of bronchial perfluorocarbon instillation on ongoing filtration. Intratracheal instillation of hydrochloric acid markedly increased filtration coefficients when compared with non-injured control lungs (2.3 +/- 0.7 vs. 0.31 +/- 0.08 ml.min(-1). mmHg(-1).100 g(-1) wet lung weight, P < 0.01). Partial liquid ventilation reduced filtration coefficients of the injured lungs (to 0.9 +/- 0.3 ml.min(-1).mmHg(-1).100 g(-1) wet lung weight, P = 0.022). Neither pulmonary artery nor capillary pressures (determined by simultaneous occlusion of inflow and outflow of the pulmonary circulation) were changed by hydrochloric acid instillation or by partial liquid ventilation. During ongoing filtration, bronchial perfluorocarbon instillation (5 ml/kg body weight) immediately reduced the amount of filtered fluid by approximately 50% (P = 0.027). In the acute phase after acid injury, partial liquid ventilation reduced pathologic fluid filtration. This effect started immediately after bronchial perfluorocarbon instillation and was not associated with changes in mean pulmonary artery, capillary, or airway pressures. The authors suggest that in the early phase of acid injury, reduction of fluid filtration contributes to the beneficial effects of partial liquid ventilation on gas exchange and lung mechanics.

Reproducibility of Lobar Perfusion and Ventilation Quantification Using SPECT/CT Segmentation Software in Lung Cancer Patients.

PubMed

Provost, Karine; Leblond, Antoine; Gauthier-Lemire, Annie; Filion, Édith; Bahig, Houda; Lord, Martin

2017-09-01

Planar perfusion scintigraphy with 99m Tc-labeled macroaggregated albumin is often used for pretherapy quantification of regional lung perfusion in lung cancer patients, particularly those with poor respiratory function. However, subdividing lung parenchyma into rectangular regions of interest, as done on planar images, is a poor reflection of true lobar anatomy. New tridimensional methods using SPECT and SPECT/CT have been introduced, including semiautomatic lung segmentation software. The present study evaluated inter- and intraobserver agreement on quantification using SPECT/CT software and compared the results for regional lung contribution obtained with SPECT/CT and planar scintigraphy. Methods: Thirty lung cancer patients underwent ventilation-perfusion scintigraphy with 99m Tc-macroaggregated albumin and 99m Tc-Technegas. The regional lung contribution to perfusion and ventilation was measured on both planar scintigraphy and SPECT/CT using semiautomatic lung segmentation software by 2 observers. Interobserver and intraobserver agreement for the SPECT/CT software was assessed using the intraclass correlation coefficient, Bland-Altman plots, and absolute differences in measurements. Measurements from planar and tridimensional methods were compared using the paired-sample t test and mean absolute differences. Results: Intraclass correlation coefficients were in the excellent range (above 0.9) for both interobserver and intraobserver agreement using the SPECT/CT software. Bland-Altman analyses showed very narrow limits of agreement. Absolute differences were below 2.0% in 96% of both interobserver and intraobserver measurements. There was a statistically significant difference between planar and SPECT/CT methods ( P < 0.001) for quantification of perfusion and ventilation for all right lung lobes, with a maximal mean absolute difference of 20.7% for the right middle lobe. There was no statistically significant difference in quantification of perfusion and ventilation for the left lung lobes using either method; however, absolute differences reached 12.0%. The total right and left lung contributions were similar for the two methods, with a mean difference of 1.2% for perfusion and 2.0% for ventilation. Conclusion: Quantification of regional lung perfusion and ventilation using SPECT/CT-based lung segmentation software is highly reproducible. This tridimensional method yields statistically significant differences in measurements for right lung lobes when compared with planar scintigraphy. We recommend that SPECT/CT-based quantification be used for all lung cancer patients undergoing pretherapy evaluation of regional lung function. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Respiratory system mechanics in acute respiratory distress syndrome.

PubMed

Kallet, Richard H; Katz, Jeffrey A

2003-09-01

Respiratory mechanics research is important to the advancement of ARDS management. Twenty-eight years ago, research on the effects of PEEP and VT indicated that the lungs of ARDS patients did not behave in a manner consistent with homogenously distributed lung injury. Both Suter and colleagues] and Katz and colleagues reported that oxygenation continued to improve as PEEP increased (suggesting lung recruitment), even though static Crs decreased and dead-space ventilation increased (suggesting concurrent lung overdistension). This research strongly suggested that without VT reduction, the favorable effects of PEEP on lung recruitment are offset by lung overdistension at end-inspiration. The implications of these studies were not fully appreciated at that time, in part because the concept of ventilator-associated lung injury was in its nascent state. Ten years later. Gattinoni and colleagues compared measurements of static pressure-volume curves with FRC and CT scans of the chest in ARDS. They found that although PEEP recruits collapsed (primarily dorsal) lung segments, it simultaneously causes overdistension of non-dependent, inflated lung regions. Furthermore, the specific compliance of the aerated, residually healthy lung tissue is essentially normal. The main implication of these findings is that traditional mechanical ventilation practice was injecting excessive volumes of gas into functionally small lungs. Therefore, the emblematic low static Crs measured in ARDS reflects not only surface tension phenomena and recruitment of collapsed airspaces but also overdistension of the remaining healthy lung. The studies reviewed in this article support the concept that lung injury in ARDS is heterogeneously distributed, with resulting disparate mechanical stresses, and indicate the additional complexity from alterations in chest wall mechanics. Most of these studies, however, were published before lung-protective ventilation. Therefore, further studies are needed to refine the understanding of the mechanical effects of lung-protective ventilation. Although low-VT ventilation is becoming a standard of care for ARDS patients, many issues remain unresolved; among them are the role of PEEP and recruitment maneuvers in either preventing or promoting lung injury and the effects of respiratory rate and graded VT reduction on mechanical stress in the lungs. The authors believe that advances in mechanical ventilation that may further improve patient outcomes are likely to come from more sophisticated monitoring capabilities (ie, the ability to measure P1 or perhaps Cslice) than from the creation of new modes of ventilatory support.

Physiologic Evaluation of Ventilation Perfusion Mismatch and Respiratory Mechanics at Different Positive End-expiratory Pressure in Patients Undergoing Protective One-lung Ventilation.

PubMed

Spadaro, Savino; Grasso, Salvatore; Karbing, Dan Stieper; Fogagnolo, Alberto; Contoli, Marco; Bollini, Giacomo; Ragazzi, Riccardo; Cinnella, Gilda; Verri, Marco; Cavallesco, Narciso Giorgio; Rees, Stephen Edward; Volta, Carlo Alberto

2018-03-01

Arterial oxygenation is often impaired during one-lung ventilation, due to both pulmonary shunt and atelectasis. The use of low tidal volume (VT) (5 ml/kg predicted body weight) in the context of a lung-protective approach exacerbates atelectasis. This study sought to determine the combined physiologic effects of positive end-expiratory pressure and low VT during one-lung ventilation. Data from 41 patients studied during general anesthesia for thoracic surgery were collected and analyzed. Shunt fraction, high V/Q and respiratory mechanics were measured at positive end-expiratory pressure 0 cm H2O during bilateral lung ventilation and one-lung ventilation and, subsequently, during one-lung ventilation at 5 or 10 cm H2O of positive end-expiratory pressure. Shunt fraction and high V/Q were measured using variation of inspired oxygen fraction and measurement of respiratory gas concentration and arterial blood gas. The level of positive end-expiratory pressure was applied in random order and maintained for 15 min before measurements. During one-lung ventilation, increasing positive end-expiratory pressure from 0 cm H2O to 5 cm H2O and 10 cm H2O resulted in a shunt fraction decrease of 5% (0 to 11) and 11% (5 to 16), respectively (P < 0.001). The PaO2/FIO2 ratio increased significantly only at a positive end-expiratory pressure of 10 cm H2O (P < 0.001). Driving pressure decreased from 16 ± 3 cm H2O at a positive end-expiratory pressure of 0 cm H2O to 12 ± 3 cm H2O at a positive end-expiratory pressure of 10 cm H2O (P < 0.001). The high V/Q ratio did not change. During low VT one-lung ventilation, high positive end-expiratory pressure levels improve pulmonary function without increasing high V/Q and reduce driving pressure.

Abdominal Muscle Activity during Mechanical Ventilation Increases Lung Injury in Severe Acute Respiratory Distress Syndrome.

PubMed

Zhang, Xianming; Wu, Weiliang; Zhu, Yongcheng; Jiang, Ying; Du, Juan; Chen, Rongchang

2016-01-01

It has proved that muscle paralysis was more protective for injured lung in severe acute respiratory distress syndrome (ARDS), but the precise mechanism is not clear. The purpose of this study was to test the hypothesis that abdominal muscle activity during mechanically ventilation increases lung injury in severe ARDS. Eighteen male Beagles were studied under mechanical ventilation with anesthesia. Severe ARDS was induced by repetitive oleic acid infusion. After lung injury, Beagles were randomly assigned into spontaneous breathing group (BIPAPSB) and abdominal muscle paralysis group (BIPAPAP). All groups were ventilated with BIPAP model for 8h, and the high pressure titrated to reached a tidal volume of 6ml/kg, the low pressure was set at 10 cmH2O, with I:E ratio 1:1, and respiratory rate adjusted to a PaCO2 of 35-60 mmHg. Six Beagles without ventilator support comprised the control group. Respiratory variables, end-expiratory volume (EELV) and gas exchange were assessed during mechanical ventilation. The levels of Interleukin (IL)-6, IL-8 in lung tissue and plasma were measured by qRT-PCR and ELISA respectively. Lung injury scores were determined at end of the experiment. For the comparable ventilator setting, as compared with BIPAPSB group, the BIPAPAP group presented higher EELV (427±47 vs. 366±38 ml) and oxygenation index (293±36 vs. 226±31 mmHg), lower levels of IL-6(216.6±48.0 vs. 297.5±71.2 pg/ml) and IL-8(246.8±78.2 vs. 357.5±69.3 pg/ml) in plasma, and lower express levels of IL-6 mRNA (15.0±3.8 vs. 21.2±3.7) and IL-8 mRNA (18.9±6.8 vs. 29.5±7.9) in lung tissues. In addition, less lung histopathology injury were revealed in the BIPAPAP group (22.5±2.0 vs. 25.2±2.1). Abdominal muscle activity during mechanically ventilation is one of the injurious factors in severe ARDS, so abdominal muscle paralysis might be an effective strategy to minimize ventilator-induce lung injury.

Regional Lung Ventilation Analysis Using Temporally Resolved Magnetic Resonance Imaging.

PubMed

Kolb, Christoph; Wetscherek, Andreas; Buzan, Maria Teodora; Werner, René; Rank, Christopher M; Kachelrie, Marc; Kreuter, Michael; Dinkel, Julien; Heuel, Claus Peter; Maier-Hein, Klaus

We propose a computer-aided method for regional ventilation analysis and observation of lung diseases in temporally resolved magnetic resonance imaging (4D MRI). A shape model-based segmentation and registration workflow was used to create an atlas-derived reference system in which regional tissue motion can be quantified and multimodal image data can be compared regionally. Model-based temporal registration of the lung surfaces in 4D MRI data was compared with the registration of 4D computed tomography (CT) images. A ventilation analysis was performed on 4D MR images of patients with lung fibrosis; 4D MR ventilation maps were compared with corresponding diagnostic 3D CT images of the patients and 4D CT maps of subjects without impaired lung function (serving as reference). Comparison between the computed patient-specific 4D MR regional ventilation maps and diagnostic CT images shows good correlation in conspicuous regions. Comparison to 4D CT-derived ventilation maps supports the plausibility of the 4D MR maps. Dynamic MRI-based flow-volume loops and spirograms further visualize the free-breathing behavior. The proposed methods allow for 4D MR-based regional analysis of tissue dynamics and ventilation in spontaneous breathing and comparison of patient data. The proposed atlas-based reference coordinate system provides an automated manner of annotating and comparing multimodal lung image data.

Budesonide ameliorates lung injury induced by large volume ventilation.

PubMed

Ju, Ying-Nan; Yu, Kai-Jiang; Wang, Guo-Nian

2016-06-04

Ventilation-induced lung injury (VILI) is a health problem for patients with acute respiratory dysfunction syndrome. The aim of this study was to investigate the effectiveness of budesonide in treating VILI. Twenty-four rats were randomized to three groups: a ventilation group, ventilation/budesonide group, and sham group were ventilated with 30 ml/kg tidal volume or only anesthesia for 4 hor saline or budesonide airway instillation immediately after ventilation. The PaO2/FiO2and wet-to-dry weight ratios, protein concentration, neutrophil count, and neutrophil elastase levels in bronchoalveolar lavage fluid (BALF) and the levels of inflammation-related factors were examined. Histological evaluation of and apoptosis measurement inthe lung were conducted. Compared with that in the ventilation group, the PaO2/FiO2 ratio was significantly increased by treatment with budesonide. The lung wet-to-dry weight ratio, total protein, neutrophil elastase level, and neutrophilcount in BALF were decreased in the budesonide group. The BALF and plasma tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, intercellular adhesion molecule (ICAM)-1, and macrophage inflammatory protein (MIP)-2 levels were decreased, whereas the IL-10 level was increased in the budesonide group. The phosphorylated nuclear factor (NF)-kBlevels in lung tissue were inhibited by budesonide. The histological changes in the lung and apoptosis were reduced by budesonide treatment. Bax, caspase-3, and cleaved caspase-3 were down-regulated, and Bcl-2 was up-regulated by budesonide. Budesonide ameliorated lung injury induced by large volume ventilation, likely by improving epithelial permeability, decreasing edema, inhibiting local and systemic inflammation, and reducing apoptosis in VILI.

Cardiorespiratory Interactions in Paediatrics: 'It's (almost always) the circulation stupid!'

PubMed

Rigby, M L; Rosenthal, M

2017-03-01

The interaction of the heart and lungs is probably the most important aspect of life and survival. Fortunately, it is not difficult to understand the fundamentals. The purpose of the lungs and their ventilation is to present oxygen to the circulation via the alveoli and to receive carbon dioxide from the circulation and then expel it. The relations of the heart and lungs and the matching of blood flow to the various organs with ventilation and lung perfusion may be disrupted by a variety of congenital or acquired heart malformations. They include those giving rise to an increased or reduced pulmonary blood flow, elevated pulmonary venous pressure or external physical pressure on the airways or lung parenchyma. Respiratory disorders which compromise cardiac function include states with reduced alveolar ventilation, those with a barrier to ventilation or perfusion, ventilation/perfusion mismatch and pulmonary vascular disease. There is also a fascinating group in which congenital disorders of the heart and lung co-exist to produce very particular modes of abnormal cardiopulmonary interaction. Copyright © 2016. Published by Elsevier Ltd.

Magnetic Resonance Imaging of Ventilation and Perfusion in the Lung

NASA Technical Reports Server (NTRS)

Prisk, Gordon Kim (Inventor); Hopkins, Susan Roberta (Inventor); Pereira De Sa, Rui Carlos (Inventor); Theilmann, Rebecca Jean (Inventor); Buxton, Richard Bruce (Inventor); Cronin, Matthew Vincent (Inventor)

2017-01-01

Methods, devices, and systems are disclosed for implementing a fully quantitative non-injectable contrast proton MRI technique to measure spatial ventilation-perfusion (VA/Q) matching and spatial distribution of ventilation and perfusion. In one aspect, a method using MRI to characterize ventilation and perfusion in a lung includes acquiring an MR image of the lung having MR data in a voxel and obtaining a breathing frequency parameter, determining a water density value, a specific ventilation value, and a perfusion value in at least one voxel of the MR image based on the MR data and using the water density value to determine an air content value, and determining a ventilation-perfusion ratio value that is the product of the specific ventilation value, the air content value, the inverse of the perfusion value, and the breathing frequency.

Perioperative lung protective ventilation in obese patients.

PubMed

Fernandez-Bustamante, Ana; Hashimoto, Soshi; Serpa Neto, Ary; Moine, Pierre; Vidal Melo, Marcos F; Repine, John E

2015-05-06

The perioperative use and relevance of protective ventilation in surgical patients is being increasingly recognized. Obesity poses particular challenges to adequate mechanical ventilation in addition to surgical constraints, primarily by restricted lung mechanics due to excessive adiposity, frequent respiratory comorbidities (i.e. sleep apnea, asthma), and concerns of postoperative respiratory depression and other pulmonary complications. The number of surgical patients with obesity is increasing, and facing these challenges is common in the operating rooms and critical care units worldwide. In this review we summarize the existing literature which supports the following recommendations for the perioperative ventilation in obese patients: (1) the use of protective ventilation with low tidal volumes (approximately 8 mL/kg, calculated based on predicted -not actual- body weight) to avoid volutrauma; (2) a focus on lung recruitment by utilizing PEEP (8-15 cmH2O) in addition to recruitment maneuvers during the intraoperative period, as well as incentivized deep breathing and noninvasive ventilation early in the postoperative period, to avoid atelectasis, hypoxemia and atelectrauma; and (3) a judicious oxygen use (ideally less than 0.8) to avoid hypoxemia but also possible reabsorption atelectasis. Obesity poses an additional challenge for achieving adequate protective ventilation during one-lung ventilation, but different lung isolation techniques have been adequately performed in obese patients by experienced providers. Postoperative efforts should be directed to avoid hypoventilation, atelectasis and hypoxemia. Further studies are needed to better define optimum protective ventilation strategies and analyze their impact on the perioperative outcomes of surgical patients with obesity.

Open-lung protective ventilation with pressure control ventilation, high-frequency oscillation, and intratracheal pulmonary ventilation results in similar gas exchange, hemodynamics, and lung mechanics.

PubMed

Sedeek, Khaled A; Takeuchi, Muneyuki; Suchodolski, Klaudiusz; Vargas, Sara O; Shimaoka, Motomu; Schnitzer, Jay J; Kacmarek, Robert M

2003-11-01

Pressure control ventilation (PCV), high-frequency oscillation (HFO), and intratracheal pulmonary ventilation (ITPV) may all be used to provide lung protective ventilation in acute respiratory distress syndrome, but the specific approach that is optimal remains controversial. Saline lavage was used to produce acute respiratory distress syndrome in 21 sheep randomly assigned to receive PCV, HFO, or ITPV as follows: positive end-expiratory pressure (PCV and ITPV) and mean airway pressure (HFO) were set in a pressure-decreasing manner after lung recruitment that achieved a ratio of Pao2/Fio2 > 400 mmHg. Respiratory rates were 30 breaths/min, 120 breaths/min, and 8 Hz, respectively, for PCV, ITPV, and HFO. Eucapnia was targeted with peak carinal pressure of no more than 35 cm H2O. Animals were then ventilated for 4 h. There were no differences among groups in gas exchange, lung mechanics, or hemodynamics. Tidal volume (PCV, 8.9 +/- 2.1 ml/kg; ITPV, 2.7 +/- 0.8 ml/kg; HFO, approximately 2.0 ml/kg) and peak carinal pressure (PCV, 30.6 +/- 2.6 cm H2O; ITPV, 22.3 +/- 4.8 cm H2O; HFO, approximately 24.3 cm H2O) were higher in PCV. Pilot histologic data showed greater interstitial hemorrhage and alveolar septal expansion in PCV than in HFO or ITPV. These data indicate that HFO, ITPV, and PCV when applied with an open-lung protective ventilatory strategy results in the same gas exchange, lung mechanics, and hemodynamic response, but pilot data indicate that lung injury may be greater with PCV.

Open lung approach vs acute respiratory distress syndrome network ventilation in experimental acute lung injury.

PubMed

Spieth, P M; Güldner, A; Carvalho, A R; Kasper, M; Pelosi, P; Uhlig, S; Koch, T; Gama de Abreu, M

2011-09-01

Setting and strategies of mechanical ventilation with positive end-expiratory pressure (PEEP) in acute lung injury (ALI) remains controversial. This study compares the effects between lung-protective mechanical ventilation according to the Acute Respiratory Distress Syndrome Network recommendations (ARDSnet) and the open lung approach (OLA) on pulmonary function and inflammatory response. Eighteen juvenile pigs were anaesthetized, mechanically ventilated, and instrumented. ALI was induced by surfactant washout. Animals were randomly assigned to mechanical ventilation according to the ARDSnet protocol or the OLA (n=9 per group). Gas exchange, haemodynamics, pulmonary blood flow (PBF) distribution, and respiratory mechanics were measured at intervals and the lungs were removed after 6 h of mechanical ventilation for further analysis. PEEP and mean airway pressure were higher in the OLA than in the ARDSnet group [15 cmH(2)O, range 14-18 cmH(2)O, compared with 12 cmH(2)O; 20.5 (sd 2.3) compared with 18 (1.4) cmH(2)O by the end of the experiment, respectively], and OLA was associated with improved oxygenation compared with the ARDSnet group after 6 h. OLA showed more alveolar overdistension, especially in gravitationally non-dependent regions, while the ARDSnet group was associated with more intra-alveolar haemorrhage. Inflammatory mediators and markers of lung parenchymal stress did not differ significantly between groups. The PBF shifted from ventral to dorsal during OLA compared with ARDSnet protocol [-0.02 (-0.09 to -0.01) compared with -0.08 (-0.12 to -0.06), dorsal-ventral gradients after 6 h, respectively]. According to the OLA, mechanical ventilation improved oxygenation and redistributed pulmonary perfusion when compared with the ARDSnet protocol, without differences in lung inflammatory response.

Low-flow venovenous CO₂ removal in association with lung protective ventilation strategy in patients who develop severe progressive respiratory acidosis after lung transplantation.

PubMed

Ruberto, F; Bergantino, B; Testa, M C; D'Arena, C; Zullino, V; Congi, P; Paglialunga, S G; Diso, D; Venuta, F; Pugliese, F

2013-09-01

Primary graft dysfunction (PGD) might occur after lung transplantation. In some severe cases, conventional therapies like ventilatory support, administration of inhaled nitric oxide (iNO), and intravenous prostacyclins are not sufficient to provide an adequate gas exchange. The aim of our study was to evaluate the use of a lung protective ventilation strategy associated with a low-flow venovenous CO2 removal treatment to reduce ventilator-associated injury in patients that develop severe PGD after lung transplantation. From January 2009 to January 2011, 3 patients developed PGD within 24 hours after lung transplantation. In addition to conventional medical treatment, including hemodynamic support, iNO and prostaglandin E1 (PGE1), we initiated a ventilatory protective strategy associated with low-flow venovenous CO2 removal treatment (LFVVECCO2R). Hemodynamic and respiratory parameters were assessed at baseline as well as after 3, 12, 24, and 48 hours. No adverse events were registered. Despite decreased baseline elevated pulmonary positive pressures, application of a protective ventilation strategy with LFVVECCO2R reduced PaCO2 and pulmonary infiltrates as well as increased pH values and PaO2/FiO2 ratios. Every patient showed simultaneous improvement of clinical and hemodynamic conditions. They were weaned from mechanical ventilation and extubated after 24 hours after the use of the low-flow venovenous CO2 removal device. The use of LFVVECCO2R together with a protective lung ventilation strategy during the perioperative period of lung transplantation may be a valid clinical strategy for patients with PGD and severe respiratory acidosis occured despite adequate mechanical ventilation. Copyright © 2013 Elsevier Inc. All rights reserved.

A description of intraoperative ventilator management in patients with acute lung injury and the use of lung protective ventilation strategies.

PubMed

Blum, James M; Maile, Michael; Park, Pauline K; Morris, Michelle; Jewell, Elizabeth; Dechert, Ronald; Rosenberg, Andrew L

2011-07-01

The incidence of acute lung injury (ALI) in hypoxic patients undergoing surgery is currently unknown. Previous studies have identified lung protective ventilation strategies that are beneficial in the treatment of ALI. The authors sought to determine the incidence and examine the use of lung protective ventilation strategies in patients receiving anesthetics with a known history of ALI. The ventilation parameters that were used in all patients were reviewed, with an average preoperative PaO₂/Fio₂ [corrected] ratio of ≤ 300 between January 1, 2005 and July 1, 2009. This dataset was then merged with a dataset of patients screened for ALI. The median tidal volume, positive end-expiratory pressure, peak inspiratory pressures, fraction inhaled oxygen, oxygen saturation, and tidal volumes were compared between groups. A total of 1,286 patients met criteria for inclusion; 242 had a diagnosis of ALI preoperatively. Comparison of patients with ALI versus those without ALI found statistically yet clinically insignificant differences between the ventilation strategies between the groups in peak inspiratory pressures and positive end-expiratory pressure but no other category. The tidal volumes in cc/kg predicted body weight were approximately 8.7 in both groups. Peak inspiratory pressures were found to be 27.87 cm H₂O on average in the non-ALI group and 29.2 in the ALI group. Similar ventilation strategies are used between patients with ALI and those without ALI. These findings suggest that anesthesiologists are not using lung protective ventilation strategies when ventilating patients with low PaO₂/Fio₂ [corrected] ratios and ALI, and instead are treating hypoxia and ALI with higher concentrations of oxygen and peak pressures.

Linking lung function to structural damage of alveolar epithelium in ventilator-induced lung injury.

PubMed

Hamlington, Katharine L; Smith, Bradford J; Dunn, Celia M; Charlebois, Chantel M; Roy, Gregory S; Bates, Jason H T

2018-05-06

Understanding how the mechanisms of ventilator-induced lung injury (VILI), namely atelectrauma and volutrauma, contribute to the failure of the blood-gas barrier and subsequent intrusion of edematous fluid into the airspace is essential for the design of mechanical ventilation strategies that minimize VILI. We ventilated mice with different combinations of tidal volume and positive end-expiratory pressure (PEEP) and linked degradation in lung function measurements to injury of the alveolar epithelium observed via scanning electron microscopy. Ventilating with both high inspiratory plateau pressure and zero PEEP was necessary to cause derangements in lung function as well as visually apparent physical damage to the alveolar epithelium of initially healthy mice. In particular, the epithelial injury was tightly associated with indicators of alveolar collapse. These results support the hypothesis that mechanical damage to the epithelium during VILI is at least partially attributed to atelectrauma-induced damage of alveolar type I epithelial cells. Copyright © 2018. Published by Elsevier B.V.

Alveolar edema dispersion and alveolar protein permeability during high volume ventilation: effect of positive end-expiratory pressure.

PubMed

de Prost, Nicolas; Roux, Damien; Dreyfuss, Didier; Ricard, Jean-Damien; Le Guludec, Dominique; Saumon, Georges

2007-04-01

To evaluate whether PEEP affects intrapulmonary alveolar edema liquid movement and alveolar permeability to proteins during high volume ventilation. Experimental study in an animal research laboratory. 46 male Wistar rats. A (99m)Tc-labeled albumin solution was instilled in a distal airway to produce a zone of alveolar flooding. Conventional ventilation (CV) was applied for 30 min followed by various ventilation strategies for 3 h: CV, spontaneous breathing, and high volume ventilation with different PEEP levels (0, 6, and 8 cmH(2)O) and different tidal volumes. Dispersion of the instilled liquid and systemic leakage of (99m)Tc-albumin from the lungs were studied by scintigraphy. The instillation protocol produced a zone of alveolar flooding that stayed localized during CV or spontaneous breathing. High volume ventilation dispersed alveolar liquid in the lungs. This dispersion was prevented by PEEP even when tidal volume was the same and thus end-inspiratory pressure higher. High volume ventilation resulted in the leakage of instilled (99m)Tc-albumin from the lungs. This increase in alveolar albumin permeability was reduced by PEEP. Albumin permeability was more affected by the amplitude of tidal excursions than by overall lung distension. PEEP prevents the dispersion of alveolar edema liquid in the lungs and lessens the increase in alveolar albumin permeability due to high volume ventilation.

Multicenter comparative study of conventional mechanical gas ventilation to tidal liquid ventilation in oleic acid injured sheep.

PubMed

Wolfson, Marla R; Hirschl, Ronald B; Jackson, J Craig; Gauvin, France; Foley, David S; Lamm, Wayne J E; Gaughan, John; Shaffer, Thomas H

2008-01-01

We performed a multicenter study to test the hypothesis that tidal liquid ventilation (TLV) would improve cardiopulmonary, lung histomorphological, and inflammatory profiles compared with conventional mechanical gas ventilation (CMV). Sheep were studied using the same volume-controlled, pressure-limited ventilator systems, protocols, and treatment strategies in three independent laboratories. Following baseline measurements, oleic acid lung injury was induced and animals were randomized to 4 hours of CMV or TLV targeted to "best PaO2" and PaCO2 35 to 60 mm Hg. The following were significantly higher (p < 0.01) during TLV than CMV: PaO2, venous oxygen saturation, respiratory compliance, cardiac output, stroke volume, oxygen delivery, ventilatory efficiency index; alveolar area, lung % gas exchange space, and expansion index. The following were lower (p < 0.01) during TLV compared with CMV: inspiratory and expiratory pause pressures, mean airway pressure, minute ventilation, physiologic shunt, plasma lactate, lung interleukin-6, interleukin-8, myeloperoxidase, and composite total injury score. No significant laboratories by treatment group interactions were found. In summary, TLV resulted in improved cardiopulmonary physiology at lower ventilatory requirements with more favorable histological and inflammatory profiles than CMV. As such, TLV offers a feasible ventilatory alternative as a lung protective strategy in this model of acute lung injury.

pRotective vEntilation with veno-venouS lung assisT in respiratory failure: A protocol for a multicentre randomised controlled trial of extracorporeal carbon dioxide removal in patients with acute hypoxaemic respiratory failure.

PubMed

McNamee, J J; Gillies, M A; Barrett, N A; Agus, A M; Beale, R; Bentley, A; Bodenham, A; Brett, S J; Brodie, D; Finney, S J; Gordon, A J; Griffiths, M; Harrison, D; Jackson, C; McDowell, C; McNally, C; Perkins, G D; Tunnicliffe, W; Vuylsteke, A; Walsh, T S; Wise, M P; Young, D; McAuley, D F

2017-05-01

One of the few interventions to demonstrate improved outcomes for acute hypoxaemic respiratory failure is reducing tidal volumes when using mechanical ventilation, often termed lung protective ventilation. Veno-venous extracorporeal carbon dioxide removal (vv-ECCO 2 R) can facilitate reducing tidal volumes. pRotective vEntilation with veno-venouS lung assisT (REST) is a randomised, allocation concealed, controlled, open, multicentre pragmatic trial to determine the clinical and cost-effectiveness of lower tidal volume mechanical ventilation facilitated by vv-ECCO 2 R in patients with acute hypoxaemic respiratory failure. Patients requiring intubation and mechanical ventilation for acute hypoxaemic respiratory failure will be randomly allocated to receive either vv-ECCO 2 R and lower tidal volume mechanical ventilation or standard care with stratification by recruitment centre. There is a need for a large randomised controlled trial to establish whether vv-ECCO 2 R in acute hypoxaemic respiratory failure can allow the use of a more protective lung ventilation strategy and is associated with improved patient outcomes.

IMPACT OF VENTILATION FREQUENCY AND PARENCHYMAL STIFFNESS ON FLOW AND PRESSURE DISTRIBUTION IN A CANINE LUNG MODEL

PubMed Central

Amini, Reza; Kaczka, David W.

2013-01-01

To determine the impact of ventilation frequency, lung volume, and parenchymal stiffness on ventilation distribution, we developed an anatomically-based computational model of the canine lung. Each lobe of the model consists of an asymmetric branching airway network subtended by terminal, viscoelastic acinar units. The model allows for empiric dependencies of airway segment dimensions and parenchymal stiffness on transpulmonary pressure. We simulated the effects of lung volume and parenchymal recoil on global lung impedance and ventilation distribution from 0.1 to 100 Hz, with mean transpulmonary pressures from 5 to 25 cmH2O. With increasing lung volume, the distribution of acinar flows narrowed and became more synchronous for frequencies below resonance. At higher frequencies, large variations in acinar flow were observed. Maximum acinar flow occurred at first antiresonance frequency, where lung impedance achieved a local maximum. The distribution of acinar pressures became very heterogeneous and amplified relative to tracheal pressure at the resonant frequency. These data demonstrate the important interaction between frequency and lung tissue stiffness on the distribution of acinar flows and pressures. These simulations provide useful information for the optimization of frequency, lung volume, and mean airway pressure during conventional ventilation or high frequency oscillation (HFOV). Moreover our model indicates that an optimal HFOV bandwidth exists between the resonant and antiresonant frequencies, for which interregional gas mixing is maximized. PMID:23872936

Alternating versus synchronous ventilation of left and right lungs in piglets.

PubMed

Versprille, A; Hrachovina, V; Jansen, J R

1995-12-01

We tested whether alternating ventilation (AV) of each lung (i.e. with a phase difference of half a ventilatory cycle) would decrease central venous pressure and so increase cardiac output when compared with simultaneous ventilation (SV) of both lungs. If, during AV, the inflated lung expands partly via compression of the opposite lung, mean lung volume will be smaller during AV than SV. As a consequence, mean intrathoracic pressure (as cited in the literature), and therefore, central venous pressure will be smaller. The experiments were performed in seven anaesthetized and paralyzed piglets using a double-piston ventilator. Minute ventilation was the same during AV and SV. Starting at SV, we alternated three times between AV and SV for periods of 10 min. During AV, central venous pressure was decreased by 0.7 mmHg and cardiac output was increased by 10 +/- 4.4% (mean, +/-SD) compared with SV. AV also resulted in increased arterial pressure. During one-sided inflation with closed outlet of the opposite lung, a pressure rise occurred in the opposite lung, indicating compression. The higher cardiac output during AV than SV can be explained by the fact that central venous pressure is lower during AV. This lower central venous pressure is very probably due to the lower mean intrathoracic pressure caused by compression of the opposite lung during unilateral inflation.

High-frequency percussive ventilation attenuates lung injury in a rabbit model of gastric juice aspiration.

PubMed

Allardet-Servent, Jérôme; Bregeon, Fabienne; Delpierre, Stéphane; Steinberg, Jean-Guillaume; Payan, Marie-José; Ravailhe, Sylvie; Papazian, Laurent

2008-01-01

To test the effects of high-frequency percussive ventilation (HFPV) compared with high-frequency oscillatory ventilation (HFOV) and low-volume conventional mechanical ventilation (LVCMV), on lung injury course in a gastric juice aspiration model. Prospective, randomized, controlled, in-vivo animal study. University animal research laboratory. Forty-three New Zealand rabbits. Lung injury was induced by intratracheal instillation of human gastric juice in order to achieve profound hypoxaemia (PaO2/FIO2< or =50). Animals were ventilated for 4h after randomization in one of the following four groups: HFPV (median pressure 15cmH2O); LVCMV (VT 6mlkg(-1) and PEEP set to reach 15cmH2O plateau pressure); HFOV (mean pressure 15cmH2O); and a high-volume control group HVCMV (VT 12ml kg(-1) and ZEEP). Static respiratory compliance increased after the ventilation period in the HFPV, LVMCV and HFOV groups, in contrast with the HVCMV group. PaO2/FIO2 improved similarly in the HFPV, LVCMV and HFOV groups, and remained lower in the HVCMV group than in the three others. Lung oedema, myeloperoxidase and histological lung injury score were higher in the HVCMV group, but not different among all others. Arterial lactate markedly increased after 4h of ventilation in the HVCMV group, while lower but similar levels were observed in the three other groups. HFPV, like HFOV and protective CMV, improves respiratory mechanics and oxygenation, and attenuates lung damage. The HFPV provides attractive lung protection, but further studies should confirm these results before introducing HFPV into the clinical arena.

[Effects of lung protective ventilation strategy combined with lung recruitment maneuver on patients with severe burn complicated with acute respiratory distress syndrome].

PubMed

Li, Xiaojian; Zhong, Xiaomin; Deng, Zhongyuan; Zhang Xuhui; Zhang, Zhi; Zhang, Tao; Tang, Wenbin; Chen, Bib; Liu, Changling; Cao, Wenjuan

2014-08-01

To investigate the effects of lung protective ventilation strategy combined with lung recruitment maneuver on ARDS complicating patients with severe burn. Clinical data of 15 severely burned patients with ARDS admitted to our burn ICU from September 2011 to September 2013 and conforming to the study criteria were analyzed. Right after the diagnosis of acute lung injury/ARDS, patients received mechanical ventilation with lung protective ventilation strategy. When the oxygenation index (OI) was below or equal to 200 mmHg (1 mmHg = 0. 133 kPa), lung recruitment maneuver was performed combining incremental positive end-expiratory pressure. When OI was above 200 mmHg, lung recruitment maneuver was stopped and ventilation with lung protective ventilation strategy was continued. When OI was above 300 mmHg, mechanical ventilation was stopped. Before combining lung recruitment maneuver, 24 h after combining lung recruitment maneuver, and at the end of combining lung recruitment maneuver, variables of blood gas analysis (pH, PaO2, and PaCO2) were obtained by blood gas analyzer, and the OI values were calculated; hemodynamic parameters including heart rate, mean arterial pressure (MAP), central venous pressure (CVP) of all patients and the cardiac output (CO), extravascular lung water index (EVLWI) of 4 patients who received pulse contour cardiac output (PiCCO) monitoring were monitored. Treatment measures and outcome of patients were recorded. Data were processed with analysis of variance of repeated measurement of a single group and LSD test. (1) Before combining lung recruitment maneuver, 24 h after combining lung recruitment maneuver, and at the end of combining lung recruitment maneuver, the levels of PaO2 and OI of patients were respectively (77 ± 8), (113 ± 5), (142 ± 6) mmHg, and (128 ± 12), (188 ± 8), (237 ± 10) mmHg. As a whole, levels of PaO2 and OI changed significantly at different time points (with F values respectively 860. 96 and 842. 09, P values below 0. 01); levels of pH and PaCO2 showed no obvious changes (with F values respectively 0.35 and 3.13, P values above 0.05). (2) Levels of heart rate, MAP, CVP of all patients and CO of 4 patients who received PiCCO monitoring showed no significant changes at different time points (with F values from 0. 13 to 4. 26, P values above 0.05). Before combining lung recruitment maneuver, 24 h after combining lung recruitment maneuver, and at the end of combining lung recruitment maneuver, the EVLWI values of 4 patients who received PiCCO monitoring were respectively (13.5 ± 1.3), (10.2 ± 1.0), (7.0 ± 0.8) mL/kg ( F =117.00, P <0.01). (3) The patients received mechanical ventilation at 2 to 72 h after burn, lasting for 14-32 (21 ± 13) d. At post injury day 3-14 (7 ± 5) d, lung recruitment maneuver was applied for 2-5 (3.0 ± 2.0) d. All 15 patients recovered without other complications. Lung protective ventilation strategy combining lung recruitment maneuver can significantly improve the oxygenation in patients with severe burn complicated with ARDS and may therefore improve the prognosis.

Fifty Years of Research in ARDS. Respiratory Mechanics in Acute Respiratory Distress Syndrome.

PubMed

Henderson, William R; Chen, Lu; Amato, Marcelo B P; Brochard, Laurent J

2017-10-01

Acute respiratory distress syndrome is a multifactorial lung injury that continues to be associated with high levels of morbidity and mortality. Mechanical ventilation, although lifesaving, is associated with new iatrogenic injury. Current best practice involves the use of small Vt, low plateau and driving pressures, and high levels of positive end-expiratory pressure. Collectively, these interventions are termed "lung-protective ventilation." Recent investigations suggest that individualized measurements of pulmonary mechanical variables rather than population-based ventilation prescriptions may be used to set the ventilator with the potential to improve outcomes beyond those achieved with standard lung protective ventilation. This review outlines the measurement and application of clinically applicable pulmonary mechanical concepts, such as plateau pressures, driving pressure, transpulmonary pressures, stress index, and measurement of strain. In addition, the concept of the "baby lung" and the utility of dynamic in addition to static measures of pulmonary mechanical variables are discussed.

Equation Discovery for Model Identification in Respiratory Mechanics of the Mechanically Ventilated Human Lung

NASA Astrophysics Data System (ADS)

Ganzert, Steven; Guttmann, Josef; Steinmann, Daniel; Kramer, Stefan

Lung protective ventilation strategies reduce the risk of ventilator associated lung injury. To develop such strategies, knowledge about mechanical properties of the mechanically ventilated human lung is essential. This study was designed to develop an equation discovery system to identify mathematical models of the respiratory system in time-series data obtained from mechanically ventilated patients. Two techniques were combined: (i) the usage of declarative bias to reduce search space complexity and inherently providing the processing of background knowledge. (ii) A newly developed heuristic for traversing the hypothesis space with a greedy, randomized strategy analogical to the GSAT algorithm. In 96.8% of all runs the applied equation discovery system was capable to detect the well-established equation of motion model of the respiratory system in the provided data. We see the potential of this semi-automatic approach to detect more complex mathematical descriptions of the respiratory system from respiratory data.

Mechanical breath profile of airway pressure release ventilation: the effect on alveolar recruitment and microstrain in acute lung injury.

PubMed

Kollisch-Singule, Michaela; Emr, Bryanna; Smith, Bradford; Roy, Shreyas; Jain, Sumeet; Satalin, Joshua; Snyder, Kathy; Andrews, Penny; Habashi, Nader; Bates, Jason; Marx, William; Nieman, Gary; Gatto, Louis A

2014-11-01

Improper mechanical ventilation settings can exacerbate acute lung injury by causing a secondary ventilator-induced lung injury. It is therefore important to establish the mechanism by which the ventilator induces lung injury to develop protective ventilation strategies. It has been postulated that the mechanism of ventilator-induced lung injury is the result of heterogeneous, elevated strain on the pulmonary parenchyma. Acute lung injury has been associated with increases in whole-lung macrostrain, which is correlated with increased pathology. However, the effect of mechanical ventilation on alveolar microstrain remains unknown. To examine whether the mechanical breath profile of airway pressure release ventilation (APRV), consisting of a prolonged pressure-time profile and brief expiratory release phase, reduces microstrain. In a randomized, nonblinded laboratory animal study, rats were randomized into a controlled mandatory ventilation group (n = 3) and an APRV group (n = 3). Lung injury was induced by polysorbate lavage. A thoracotomy was performed and an in vivo microscope was placed on the lungs to measure alveolar mechanics. In the controlled mandatory ventilation group, multiple levels of positive end-expiratory pressure (PEEP; 5, 10, 16, 20, and 24 cm H2O) were tested. In the APRV group, decreasing durations of expiratory release (time at low pressure [T(low)]) were tested. The T(low) was set to achieve ratios of termination of peak expiratory flow rate (T-PEFR) to peak expiratory flow rate (PEFR) of 10%, 25%, 50%, and 75% (the smaller this ratio is [ie, 10%], the more time the lung is exposed to low pressure during the release phase, which decreases end-expiratory lung volume and potentiates derecruitment). Alveolar perimeters were measured at peak inspiration and end expiration using digital image analysis, and strain was calculated by normalizing the change in alveolar perimeter length to the original length. Macrostrain was measured by volume displacement. Higher PEEP (16-24 cm H2O) and a brief T(low) (APRV T-PEFR to PEFR ratio of 75%) reduced microstrain. Microstrain was minimized with an APRV T-PEFR to PEFR ratio of 75% (mean [SEM], 0.05 [0.03]) and PEEP of 16 cm H2O (mean [SEM], 0.09 [0.08]), but an APRV T-PEFR to PEFR ratio of 75% also promoted alveolar recruitment compared with PEEP of 16 cm H2O (mean [SEM] total inspiratory area, 52.0% [2.9%] vs 29.4% [4.3%], respectively; P < .05). Whole-lung strain was correlated with alveolar microstrain in tested settings (P < .05) except PEEP of 16 cm H2O (P > .05). Increased positive-end expiratory pressure and reduced time at low pressure (decreased T(low)) reduced alveolar microstrain. Reduced microstrain and improved alveolar recruitment using an APRV T-PEFR to PEFR ratio of 75% may be the mechanism of lung protection seen in previous clinical and animal studies.

REDUCTION IN INSPIRATORY FLOW ATTENUATES IL-8 RELEASE AND MAPK ACTIVATION OF LUNG OVERSTRETCH

EPA Science Inventory

Lung overstretch involves mechanical factors, including large tidal volumes (VT), which induce inflammatory responses. The current authors hypothesised that inspiratory flow contributes to ventilator-induced inflammation. Buffer-perfused rabbit lungs were ventilated for 2 h with ...

TH-E-BRF-02: 4D-CT Ventilation Image-Based IMRT Plans Are Dosimetrically Comparable to SPECT Ventilation Image-Based Plans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kida, S; University of Tokyo Hospital, Bunkyo, Tokyo; Bal, M

Purpose: An emerging lung ventilation imaging method based on 4D-CT can be used in radiotherapy to selectively avoid irradiating highly-functional lung regions, which may reduce pulmonary toxicity. Efforts to validate 4DCT ventilation imaging have been focused on comparison with other imaging modalities including SPECT and xenon CT. The purpose of this study was to compare 4D-CT ventilation image-based functional IMRT plans with SPECT ventilation image-based plans as reference. Methods: 4D-CT and SPECT ventilation scans were acquired for five thoracic cancer patients in an IRB-approved prospective clinical trial. The ventilation images were created by quantitative analysis of regional volume changes (amore » surrogate for ventilation) using deformable image registration of the 4D-CT images. A pair of 4D-CT ventilation and SPECT ventilation image-based IMRT plans was created for each patient. Regional ventilation information was incorporated into lung dose-volume objectives for IMRT optimization by assigning different weights on a voxel-by-voxel basis. The objectives and constraints of the other structures in the plan were kept identical. The differences in the dose-volume metrics have been evaluated and tested by a paired t-test. SPECT ventilation was used to calculate the lung functional dose-volume metrics (i.e., mean dose, V20 and effective dose) for both 4D-CT ventilation image-based and SPECT ventilation image-based plans. Results: Overall there were no statistically significant differences in any dose-volume metrics between the 4D-CT and SPECT ventilation imagebased plans. For example, the average functional mean lung dose of the 4D-CT plans was 26.1±9.15 (Gy), which was comparable to 25.2±8.60 (Gy) of the SPECT plans (p = 0.89). For other critical organs and PTV, nonsignificant differences were found as well. Conclusion: This study has demonstrated that 4D-CT ventilation image-based functional IMRT plans are dosimetrically comparable to SPECT ventilation image-based plans, providing evidence to use 4D-CT ventilation imaging for clinical applications. Supported in part by Free to Breathe Young Investigator Research Grant and NIH/NCI R01 CA 093626. The authors thank Philips Radiation Oncology Systems for the Pinnacle3 treatment planning systems.« less

WE-FG-206-08: Pulmonary Functional Imaging Biomarkers of NSCLC to Guide and Optimize Functional Lung Avoidance Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheikh, Khadija; Capaldi, Dante PI; Parraga, Grace

Purpose: Functional lung avoidance radiotherapy promises optimized therapy planning by minimizing dose to well-functioning lung and maximizing dose to the rest of the lung. Patients with NSCLC commonly present with co-morbid COPD and heterogeneously distributed ventilation abnormalities stemming from emphysema, airways disease, and tumour burden. We hypothesized that pulmonary functional imaging methods may be used to optimize radiotherapy plans to avoid regions of well-functioning lung and significantly improve outcomes like quality-of-life and survival. To ascertain the utility of functional lung avoidance therapy in clinical practice, we measured COPD phenotypes in NSCLC patients enrolled in a randomized-controlled-clinical-trial prior to curative intentmore » therapy. Methods: Thirty stage IIIA/IIIB NSCLC patients provided written informed consent to a randomized-controlled-clinical-trial ( http://clinicaltrials.gov/ct2/show/NCT02002052 ) comparing outcomes in patients randomized to standard or image-guided radiotherapy. Hyperpolarized noble gas MRI ventilation-defect-percent (VDP) (Kirby et al, Acad Radiol, 2012) as well as CT-emphysema measurements were determined. Patients were stratified based on quantitative imaging evidence of ventilation-defects and emphysema into two subgroups: 1) tumour-specific ventilation defects only (TSD), and, 2) tumour-specific and other ventilation defects with and without emphysema (TSD{sub VE}). Receiver-operating-characteristic (ROC) curves were used to characterize the performance of clinical measures as predictors of the presence of non-tumour specific ventilation defects. Results: Twenty-one out of thirty subjects (70%) had non-tumour specific ventilation defects (TSD{sub VE}) and nine subjects had ONLY tumour-specific defects (TSD). Subjects in the TSD{sub VE} group had significantly greater smoking-history (p=.006) and airflow obstruction (FEV{sub 1}/FVC) (p=.001). ROC analysis demonstrated an 87% classification rate for smoking pack-years, 90% for FEV{sub 1}/FVC, and 56% for tumour RECIST measurements for identifying patients with non-tumour and tumour-specific ventilation abnormalities. Conclusion: 70% of NSCLC patients had ventilation abnormalities stemming from emphysema, airways disease and tumour burden. Smoking-history and airflow obstruction, but not RECIST, identified NSCLC patients with ventilation abnormalities appropriate for functional lung avoidance therapy.« less

SU-E-J-90: Lobar-Level Lung Ventilation Analysis Using 4DCT and Deformable Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, K; Bayouth, J; Patton, T

2015-06-15

Purpose: To assess regional changes in human lung ventilation and mechanics using four-dimensional computed tomography (4DCT) and deformable image registration. This work extends our prior analysis of the entire lung to a lobe-based analysis. Methods: 4DCT images acquired from 20 patients prior to radiation therapy (RT) were used for this analysis. Jacobian ventilation and motion maps were computed from the displacement field after deformable image registration between the end of expiration breathing phase and the end of inspiration breathing phase. The lobes were manually segmented on the reference phase by a medical physicist expert. The voxel-by-voxel ventilation and motion magnitudemore » for all subjects were grouped by lobes and plotted into cumulative voxel frequency curves respectively. In addition, to eliminate the effect of different breathing efforts across subjects, we applied the inter-subject equivalent lung volume (ELV) method on a subset of the cohort and reevaluated the lobar ventilation. Results: 95% of voxels in the lung are expanding during inspiration. However, some local regions of lung tissue show far more expansion than others. The greatest expansion with respiration occurs within the lower lobes; between exhale and inhale the median expansion in lower lobes is approximately 15%, while the median expansion in upper lobes is 10%. This appears to be driven by a subset of lung tissues within the lobe that have greater expansion; twice the number of voxels in the lower lobes (20%) expand by > 30% when compared to the upper lobes (10%). Conclusion: Lung ventilation and motion show significant difference on the lobar level. There are different lobar fractions of driving voxels that contribute to the major expansion of the lung. This work was supported by NIH grant CA166703.« less

Abdominal Muscle Activity during Mechanical Ventilation Increases Lung Injury in Severe Acute Respiratory Distress Syndrome

PubMed Central

Zhang, Xianming; Wu, Weiliang; Zhu, Yongcheng; Jiang, Ying; Du, Juan; Chen, Rongchang

2016-01-01

Objective It has proved that muscle paralysis was more protective for injured lung in severe acute respiratory distress syndrome (ARDS), but the precise mechanism is not clear. The purpose of this study was to test the hypothesis that abdominal muscle activity during mechanically ventilation increases lung injury in severe ARDS. Methods Eighteen male Beagles were studied under mechanical ventilation with anesthesia. Severe ARDS was induced by repetitive oleic acid infusion. After lung injury, Beagles were randomly assigned into spontaneous breathing group (BIPAPSB) and abdominal muscle paralysis group (BIPAPAP). All groups were ventilated with BIPAP model for 8h, and the high pressure titrated to reached a tidal volume of 6ml/kg, the low pressure was set at 10 cmH2O, with I:E ratio 1:1, and respiratory rate adjusted to a PaCO2 of 35–60 mmHg. Six Beagles without ventilator support comprised the control group. Respiratory variables, end-expiratory volume (EELV) and gas exchange were assessed during mechanical ventilation. The levels of Interleukin (IL)-6, IL-8 in lung tissue and plasma were measured by qRT-PCR and ELISA respectively. Lung injury scores were determined at end of the experiment. Results For the comparable ventilator setting, as compared with BIPAPSB group, the BIPAPAP group presented higher EELV (427±47 vs. 366±38 ml) and oxygenation index (293±36 vs. 226±31 mmHg), lower levels of IL-6(216.6±48.0 vs. 297.5±71.2 pg/ml) and IL-8(246.8±78.2 vs. 357.5±69.3 pg/ml) in plasma, and lower express levels of IL-6 mRNA (15.0±3.8 vs. 21.2±3.7) and IL-8 mRNA (18.9±6.8 vs. 29.5±7.9) in lung tissues. In addition, less lung histopathology injury were revealed in the BIPAPAP group (22.5±2.0 vs. 25.2±2.1). Conclusion Abdominal muscle activity during mechanically ventilation is one of the injurious factors in severe ARDS, so abdominal muscle paralysis might be an effective strategy to minimize ventilator-induce lung injury. PMID:26745868

[Thoracoscopic thymectomy with carbon dioxide insufflation in the mediastinum].

PubMed

Ferrero-Coloma, C; Navarro-Martinez, J; Bolufer, S; Rivera-Cogollos, M J; Alonso-García, F J; Tarí-Bas, M I

2015-02-01

The case is presented of a 71 year-old male, diagnosed with a thymoma. A thoracoscopic thymectomy was performed using the carbon dioxide insufflation technique in the mediastinum. During the procedure, while performing one-lung ventilation, the patient's respiration worsened. The contralateral lung had collapsed, as carbon dioxide was travelling from the mediastinum to the thorax through the opened pleura. Two-lung ventilation was decided upon, which clearly improved oxygenation in the arterial gases and airway pressures. Both pH and pCO2 stabilized. The surgical approach and the carbon dioxide technique were continued because 2-lung ventilation did not affect the surgical procedure. This technique has many serious complications and it should always be performed using 2-lung ventilation. Copyright © 2014 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

TU-G-BRA-04: Changes in Regional Lung Function Measured by 4D-CT Ventilation Imaging for Thoracic Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Y; Kadoya, N; Kabus, S

Purpose: To test the hypothesis: 4D-CT ventilation imaging can show the known effects of radiotherapy on lung function: (1) radiation-induced ventilation reductions, and (2) ventilation increases caused by tumor regression. Methods: Repeat 4D-CT scans (pre-, mid- and/or post-treatment) were acquired prospectively for 11 thoracic cancer patients in an IRB-approved clinical trial. A ventilation image for each time point was created using deformable image registration and the Hounsfield unit (HU)-based or Jacobian-based metric. The 11 patients were divided into two subgroups based on tumor volume reduction using a threshold of 5 cm{sup 3}. To quantify radiation-induced ventilation reduction, six patients whomore » showed a small tumor volume reduction (<5 cm{sup 3}) were analyzed for dose-response relationships. To investigate ventilation increase caused by tumor regression, two of the other five patients were analyzed to compare ventilation changes in the lung lobes affected and unaffected by the tumor. The remaining three patients were excluded because there were no unaffected lobes. Results: Dose-dependent reductions of HU-based ventilation were observed in a majority of the patient-specific dose-response curves and in the population-based dose-response curve, whereas no clear relationship was seen for Jacobian-based ventilation. The post-treatment population-based dose-response curve of HU-based ventilation demonstrated the average ventilation reductions of 20.9±7.0% at 35–40 Gy (equivalent dose in 2-Gy fractions, EQD2), and 40.6±22.9% at 75–80 Gy EQD2. Remarkable ventilation increases in the affected lobes were observed for the two patients who showed an average tumor volume reduction of 37.1 cm{sup 3} and re-opening airways. The mid-treatment increase in HU-based ventilation of patient 3 was 100.4% in the affected lobes, which was considerably greater than 7.8% in the unaffected lobes. Conclusion: This study has demonstrated that 4D-CT ventilation imaging shows the known effects of radiotherapy on lung function: radiation-induced ventilation reduction and ventilation increase caused by tumor regression, providing validation for 4D-CT ventilation imaging. This study was supported in part by a National Lung Cancer Partnership Young Investigator Research grant.« less

SU-E-J-178: A Normalization Method Can Remove Discrepancy in Ventilation Function Due to Different Breathing Patterns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, H; Yu, N; Stephans, K

2014-06-01

Purpose: To develop a normalization method to remove discrepancy in ventilation function due to different breathing patterns. Methods: Twenty five early stage non-small cell lung cancer patients were included in this study. For each patient, a ten phase 4D-CT and the voluntarily maximum inhale and exhale CTs were acquired clinically and retrospectively used for this study. For each patient, two ventilation maps were calculated from voxel-to-voxel CT density variations from two phases of the quiet breathing and two phases of the extreme breathing. For the quiet breathing, 0% (inhale) and 50% (exhale) phases from 4D-CT were used. An in-house toolmore » was developed to calculate and display the ventilation maps. To enable normalization, the whole lung of each patient was evenly divided into three parts in the longitude direction at a coronal image with a maximum lung cross section. The ratio of cumulated ventilation from the top one-third region to the middle one-third region of the lung was calculated for each breathing pattern. Pearson's correlation coefficient was calculated on the ratios of the two breathing patterns for the group. Results: For each patient, the ventilation map from the quiet breathing was different from that of the extreme breathing. When the cumulative ventilation was normalized to the middle one-third of the lung region for each patient, the normalized ventilation functions from the two breathing patterns were consistent. For this group of patients, the correlation coefficient of the normalized ventilations for the two breathing patterns was 0.76 (p < 0.01), indicating a strong correlation in the ventilation function measured from the two breathing patterns. Conclusion: For each patient, the ventilation map is dependent of the breathing pattern. Using a regional normalization method, the discrepancy in ventilation function induced by the different breathing patterns thus different tidal volumes can be removed.« less

Work of breathing during lung-protective ventilation in patients with acute lung injury and acute respiratory distress syndrome: a comparison between volume and pressure-regulated breathing modes.

PubMed

Kallet, Richard H; Campbell, Andre R; Dicker, Rochelle A; Katz, Jeffrey A; Mackersie, Robert C

2005-12-01

Pressure-control ventilation (PCV) and pressure-regulated volume-control (PRVC) ventilation are used during lung-protective ventilation because the high, variable, peak inspiratory flow rate (V (I)) may reduce patient work of breathing (WOB) more than the fixed V (I) of volume-control ventilation (VCV). Patient-triggered breaths during PCV and PRVC may result in excessive tidal volume (V(T)) delivery unless the inspiratory pressure is reduced, which in turn may decrease the peak V (I). We tested whether PCV and PRVC reduce WOB better than VCV with a high, fixed peak V (I) (75 L/min) while also maintaining a low V(T) target. Fourteen nonconsecutive patients with acute lung injury or acute respiratory distress syndrome were studied prospectively, using a random presentation of ventilator modes in a crossover, repeated-measures design. A target V(T) of 6.4 + 0.5 mL/kg was set during VCV and PRVC. During PCV the inspiratory pressure was set to achieve the same V(T). WOB and other variables were measured with a pulmonary mechanics monitor (Bicore CP-100). There was a nonsignificant trend toward higher WOB (in J/L) during PCV (1.27 + 0.58 J/L) and PRVC (1.35 + 0.60 J/L), compared to VCV (1.09 + 0.59 J/L). While mean V(T) was not statistically different between modes, in 40% of patients, V(T) markedly exceeded the lung-protective ventilation target during PRVC and PCV. During lung-protective ventilation, PCV and PRVC offer no advantage in reducing WOB, compared to VCV with a high flow rate, and in some patients did not allow control of V(T) to be as precise.

Ventilation practices in subarachnoid hemorrhage: a cohort study exploring the use of lung protective ventilation.

PubMed

Marhong, Jonathan D; Ferguson, Niall D; Singh, Jeffrey M

2014-10-01

Acute respiratory distress syndrome (ARDS) is common following aneurysmal subarachnoid hemorrhage (SAH), but the influence of mechanical ventilator settings on its development is unclear. We sought to determine adherence to lung protective thresholds in ventilated patients with SAH and describe the association between ventilator settings and subsequent development of ARDS. We conducted a retrospective cohort study of consecutive patients receiving mechanical ventilation within 72 h of SAH at a single academic center. Ventilator settings and blood gas data were collected twice daily for the first 7 days of ventilation along with ICU and hospital outcomes. Lung protective ventilation was defined as follows: tidal volume ≤8 mL/kg of predicted body weight, positive end-expiratory pressure (PEEP) ≥5 cm H(2)O, and peak or plateau pressure ≤30 cm H(2)O. The development of ARDS was ascertained retrospectively by PaO(2)/FiO(2) ≤300 with new bilateral lung opacities on chest X-ray within one day of hypoxemia. We identified 62 patients who underwent early mechanical ventilation following SAH. PS and Continuous Positive Airway Pressure were common ventilator modes with a median tidal volume of 7.8 mL/kg [interquartile range 6.8-8.8], median peak pressure of 14 cm H(2)O [IQR 12-17], and median PEEP of 5 cm H(2)O [IQR 5-6]. Adherence to tidal volumes ≤8 mL/kg was seen in 64 % of all observations and peak pressures <30 cm H(2)O were 94 % of all observations. All three lung protective criteria were seen in 58 % of all observations. Thirty-one patients (50 %) were determined to have ARDS. ARDS patients were more frequently ventilated with a peak pressure >30 cm H(2)O (11.3 % of ARDS ventilation days vs. 0 % of non-ARDS ventilation days; p < 0.01). Initial tidal volume was not associated with subsequent development of ARDS in univariate (p = 0.6) or multivariate analysis (p = 0.49). Only the number of ARDS risk factors was independently associated with the development of ARDS (Adjusted Odds Ratio 2.8 per additional risk factor [95 % CI 1.2-6.5]). Patients with SAH requiring mechanical ventilation frequently breathe spontaneously, generating tidal volumes above usual protective thresholds regardless of meeting ARDS criteria. In patients with SAH, the presence of an additional ARDS risk factor should prompt close screening for the development of ARDS and consideration of adjustment of ventilator settings to meet lung protective thresholds.

Quantification of asymmetric lung pathophysiology as a guide to the use of simultaneous independent lung ventilation in posttraumatic and septic adult respiratory distress syndrome.

PubMed Central

Siegel, J H; Stoklosa, J C; Borg, U; Wiles, C E; Sganga, G; Geisler, F H; Belzberg, H; Wedel, S; Blevins, S; Goh, K C

1985-01-01

The management of impaired respiratory gas exchange in patients with nonuniform posttraumatic and septic adult respiratory distress syndrome (ARDS) contains its own therapeutic paradox, since the need for volume-controlled ventilation and PEEP in the lung with the most reduced compliance increases pulmonary barotrauma to the better lung. A computer-based system has been developed by which respiratory pressure-flow-volume relations and gas exchange characteristics can be obtained and respiratory dynamic and static compliance curves computed and displayed for each lung, as a means of evaluating the effectiveness of ventilation therapy in ARDS. Using these techniques, eight patients with asymmetrical posttraumatic or septic ARDS, or both, have been managed using simultaneous independent lung ventilation (SILV). The computer assessment technique allows quantification of the nonuniform ARDS pattern between the two lungs. This enabled SILV to be utilized using two synchronized servo-ventilators at different pressure-flow-volumes, inspiratory/expiratory ratios, and PEEP settings to optimize the ventilatory volumes and gas exchange of each lung, without inducing excess barotrauma in the better lung. In the patients with nonuniform ARDS, conventional ventilation was not effective in reducing shunt (QS/QT) or in permitting a lower FIO2 to be used for maintenance of an acceptable PaO2. SILV reduced per cent v-a shunt and permitted a higher PaO2 at lower FIO2. Also, there was x-ray evidence of ARDS improvement in the poorer lung. While the ultimate outcome was largely dependent on the patient's injury and the adequacy of the septic host defense, by utilizing the SILV technique to match the quantitative aspects of respiratory dysfunction in each lung at specific times in the clinical course, it was possible to optimize gas exchange, to reduce barotrauma, and often to reverse apparently fixed ARDS changes. In some instances, this type of physiologically directed ventilatory therapy appeared to contribute to a successful recovery. Images FIG. 10. PMID:3901940

Attenuation of ventilation-induced diaphragm dysfunction through toll-like receptor 4 and nuclear factor-κB in a murine endotoxemia model.

PubMed

Li, Li-Fu; Liu, Yung-Yang; Chen, Ning-Hung; Chen, Yen-Huey; Huang, Chung-Chi; Kao, Kuo-Chin; Chang, Chih-Hao; Chuang, Li-Pang; Chiu, Li-Chung

2018-06-20

Mechanical ventilation (MV) is often used to maintain life in patients with sepsis and sepsis-related acute lung injury. However, controlled MV may cause diaphragm weakness due to muscle injury and atrophy, an effect termed ventilator-induced diaphragm dysfunction (VIDD). Toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) signaling pathways may elicit sepsis-related acute inflammatory responses and muscle protein degradation and mediate the pathogenic mechanisms of VIDD. However, the mechanisms regulating the interactions between VIDD and endotoxemia are unclear. We hypothesized that mechanical stretch with or without endotoxin treatment would augment diaphragmatic structural damage, the production of free radicals, muscle proteolysis, mitochondrial dysfunction, and autophagy of the diaphragm via the TLR4/NF-κB pathway. Male C57BL/6 mice, either wild-type or TLR4-deficient, aged between 6 and 8 weeks were exposed to MV (6 mL/kg or 10 mL/kg) with or without endotoxemia for 8 h. Nonventilated mice were used as controls. MV with endotoxemia aggravated VIDD, as demonstrated by the increases in the expression levels of TLR4, caspase-3, atrogin-1, muscle ring finger-1, and microtubule-associated protein light chain 3-II. In addition, increased NF-κB phosphorylation and oxidative loads, disorganized myofibrils, disrupted mitochondria, autophagy, and myonuclear apoptosis were also observed. Furthermore, MV with endotoxemia reduced P62 levels and diaphragm muscle fiber size (P < 0.05). Endotoxin-exacerbated VIDD was attenuated by pharmacologic inhibition with a NF-κB inhibitor or in TLR4-deficient mice (P < 0.05). Our data indicate that endotoxin-augmented MV-induced diaphragmatic injury occurs through the activation of the TLR4/NF-κB signaling pathway.

Transfer factor, lung volumes, resistance and ventilation distribution in healthy adults.

PubMed

Verbanck, Sylvia; Van Muylem, Alain; Schuermans, Daniel; Bautmans, Ivan; Thompson, Bruce; Vincken, Walter

2016-01-01

Monitoring of chronic lung disease requires reference values of lung function indices, including putative markers of small airway function, spanning a wide age range.We measured spirometry, transfer factor of the lung for carbon monoxide (TLCO), static lung volume, resistance and ventilation distribution in a healthy population, studying at least 20 subjects per sex and per decade between the ages of 20 and 80 years.With respect to the Global Lung Function Initiative reference data, our subjects had average z-scores for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and FEV1/FVC of -0.12, 0.04 and -0.32, respectively. Reference equations were obtained which could account for a potential dependence of index variability on age and height. This was done for (but not limited to) indices that are pertinent to asthma and chronic obstructive pulmonary disease studies: forced expired volume in 6 s, forced expiratory flow, TLCO, specific airway conductance, residual volume (RV)/total lung capacity (TLC), and ventilation heterogeneity in acinar and conductive lung zones.Deterioration in acinar ventilation heterogeneity and lung clearance index with age were more marked beyond 60 years, and conductive ventilation heterogeneity showed the greatest increase in variability with age. The most clinically relevant deviation from published reference values concerned RV/TLC values, which were considerably smaller than American Thoracic Society/European Respiratory Society-endorsed reference values. Copyright ©ERS 2016.

Comparison between conventional and protective one-lung ventilation for ventilator-assisted thoracic surgery.

PubMed

Ahn, H J; Kim, J A; Yang, M; Shim, W S; Park, K J; Lee, J J

2012-09-01

Recent papers suggest protective ventilation (PV) as a primary ventilation strategy during one-lung ventilation (OLV) to reduce postoperative pulmonary morbidity. However, data regarding the advantage of the PV strategy in patients with normal preoperative pulmonary function are inconsistent, especially in the case of minimally invasive thoracic surgery. Therefore we compared conventional OLV (VT 10 ml/kg, FiO2 1.0, zero PEEP) to protective OLV (VT 6 ml/kg, FiO2 0.5, PEEP 5 cmH2O) in patients with normal preoperative pulmonary function tests undergoing video-assisted thoracic surgery. Oxygenation, respiratory mechanics, plasma interleukin-6 and malondialdehyde levels were measured at baseline, 15 and 60 minutes after OLV and 15 minutes after restoration of two-lung ventilation. PaO2 and PaO2/FiO2 were higher in conventional OLV than in protective OLV (P<0.001). Interleukin-6 and malondialdehyde increased over time in both groups (P<0.05); however, the magnitudes of increase were not different between the groups. Postoperatively there were no differences in the number of patients with PaO2/FiO2<300 mmHg or abnormalities on chest radiography. Protective ventilation did not provide advantages over conventional ventilation for video-assisted thoracic surgery in this group of patients with normal lung function.

Non-invasive ventilation in prone position for refractory hypoxemia after bilateral lung transplantation.

PubMed

Feltracco, Paolo; Serra, Eugenio; Barbieri, Stefania; Persona, Paolo; Rea, Federico; Loy, Monica; Ori, Carlo

2009-01-01

Temporary graft dysfunction with gas exchange abnormalities is a common finding during the postoperative course of a lung transplant and is often determined by the post-reimplantation syndrome. Supportive measures including oxygen by mask, inotropes, diuretics, and pulmonary vasodilators are usually effective in non-severe post-reimplantation syndromes. However, in less-responsive clinical pictures, tracheal intubation with positive pressure ventilation, or non-invasive positive pressure ventilation (NIV), is necessary. We report on the clinical course of two patients suffering from refractory hypoxemia due to post-reimplantation syndrome treated with NIV in the prone and Trendelenburg positions. NIV was well tolerated and led to resolution of atelectactic areas and dishomogeneous lung infiltrates. Repeated turning from supine to prone under non invasive ventilation determined a stable improvement of gas exchange and prevented a more invasive approach. Even though NIV in the prone position has not yet entered into clinical practice, it could be an interesting option to achieve a better match between ventilation and perfusion. This technique, which we successfully applied in lung transplantation, can be easily extended to other lung diseases with non-recruitable dorso-basal areas.

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J.; Hugo, Geoffrey

Purpose: Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), amore » novel technique for functional lung imaging. Methods: The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4–6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. Results: The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r{sup -}{sub Inter}=0.52±0.25, which was significantly lower than for intrafraction pairs (r{sup -}{sub Intra}=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV{sup -}{sub Inter}|=0.42±0.65 and |ΔV{sup -}{sub Intra}|=0.32±0.53, respectively (p < 10{sup −15}). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. Conclusions: The authors’ data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.« less

Measuring interfraction and intrafraction lung function changes during radiation therapy using four-dimensional cone beam CT ventilation imaging.

PubMed

Kipritidis, John; Hugo, Geoffrey; Weiss, Elisabeth; Williamson, Jeffrey; Keall, Paul J

2015-03-01

Adaptive ventilation guided radiation therapy could minimize the irradiation of healthy lung based on repeat lung ventilation imaging (VI) during treatment. However the efficacy of adaptive ventilation guidance requires that interfraction (e.g., week-to-week), ventilation changes are not washed out by intrafraction (e.g., pre- and postfraction) changes, for example, due to patient breathing variability. The authors hypothesize that patients undergoing lung cancer radiation therapy exhibit larger interfraction ventilation changes compared to intrafraction function changes. To test this, the authors perform the first comparison of interfraction and intrafraction lung VI pairs using four-dimensional cone beam CT ventilation imaging (4D-CBCT VI), a novel technique for functional lung imaging. The authors analyzed a total of 215 4D-CBCT scans acquired for 19 locally advanced non-small cell lung cancer (LA-NSCLC) patients over 4-6 weeks of radiation therapy. This set of 215 scans was sorted into 56 interfraction pairs (including first day scans and each of treatment weeks 2, 4, and 6) and 78 intrafraction pairs (including pre/postfraction scans on the same-day), with some scans appearing in both sets. VIs were obtained from the Jacobian determinant of the transform between the 4D-CBCT end-exhale and end-inhale images after deformable image registration. All VIs were deformably registered to their corresponding planning CT and normalized to account for differences in breathing effort, thus facilitating image comparison in terms of (i) voxelwise Spearman correlations, (ii) mean image differences, and (iii) gamma pass rates for all interfraction and intrafraction VI pairs. For the side of the lung ipsilateral to the tumor, we applied two-sided t-tests to determine whether interfraction VI pairs were more different than intrafraction VI pairs. The (mean ± standard deviation) Spearman correlation for interfraction VI pairs was r̄(Inter)=0.52±0.25, which was significantly lower than for intrafraction pairs (r̄(Intra)=0.67±0.20, p = 0.0002). Conversely, mean absolute ventilation differences were larger for interfraction pairs than for intrafraction pairs, with |ΔV̄(Inter)|=0.42±0.65 and |ΔV̄(Intra)|=0.32±0.53, respectively (p < 10(-15)). Applying a gamma analysis with ventilation/distance tolerance of 25%/10 mm, we observed mean pass rate of (69% ± 20%) for interfraction VIs, which was significantly lower compared to intrafraction pairs (80% ± 15%, with p ∼ 0.0003). Compared to the first day scans, all patients experienced at least one subsequent change in median ipsilateral ventilation ≥10%. Patients experienced both positive and negative ventilation changes throughout treatment, with the maximum change occurring at different weeks for different patients. The authors' data support the hypothesis that interfraction ventilation changes are larger than intrafraction ventilation changes for LA-NSCLC patients over a course of conventional lung cancer radiation therapy. Longitudinal ventilation changes are observed to be highly patient-dependent, supporting a possible role for adaptive ventilation guidance based on repeat 4D-CBCT VIs. We anticipate that future improvement of 4D-CBCT image reconstruction algorithms will improve the capability of 4D-CBCT VI to resolve interfraction ventilation changes.

Low tidal volume and high positive end-expiratory pressure mechanical ventilation results in increased inflammation and ventilator-associated lung injury in normal lungs.

PubMed

Hong, Caron M; Xu, Da-Zhong; Lu, Qi; Cheng, Yunhui; Pisarenko, Vadim; Doucet, Danielle; Brown, Margaret; Aisner, Seena; Zhang, Chunxiang; Deitch, Edwin A; Delphin, Ellise

2010-06-01

Protective mechanical ventilation with low tidal volume (Vt) and low plateau pressure reduces mortality and decreases the length of mechanical ventilation in patients with acute respiratory distress syndrome. Mechanical ventilation that will protect normal lungs during major surgical procedures of long duration may improve postoperative outcomes. We performed an animal study comparing 3 ventilation strategies used in the operating room in normal lungs. We compared the effects on pulmonary mechanics, inflammatory mediators, and lung tissue injury. Female pigs were randomized into 3 groups. Group H-Vt/3 (n = 6) was ventilated with a Vt of 15 mL/kg predicted body weight (PBW)/positive end-expiratory pressure (PEEP) of 3 cm H(2)O, group L-Vt/3 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 3 cm H(2)O, and group L-Vt/10 (n = 6) with a Vt of 6 mL/kg PBW/PEEP of 10 cm H(2)O, for 8 hours. Hemodynamics, airway mechanics, arterial blood gases, and inflammatory markers were monitored. Bronchoalveolar lavage (BAL) was analyzed for inflammatory markers and protein concentration. The right lower lobe was assayed for mRNA of specific cytokines. The right lower lobe and right upper lobe were evaluated histologically. In contrast to groups H-Vt/3 and L-Vt/3, group L-Vt/10 exhibited a 6-fold increase in inflammatory mediators in BAL (P < 0.001). Cytokines in BAL were similar in groups H-Vt/3 and L-Vt/3. Group H-Vt/3 had a significantly lower lung injury score than groups L-Vt/3 and L-Vt/10. Comparing intraoperative strategies, ventilation with high PEEP resulted in increased production of inflammatory markers. Low PEEP resulted in lower levels of inflammatory markers. High Vt/low PEEP resulted in less histologic lung injury.

Pneumothorax - infants

MedlinePlus

... easily. If the baby needs a breathing machine (mechanical ventilator), extra pressure on the baby's lungs, from ... problems. If the baby needs a breathing machine (mechanical ventilator), extra pressure on the baby's lungs from ...

Regional gas transport in the heterogeneous lung during oscillatory ventilation

PubMed Central

Herrmann, Jacob; Tawhai, Merryn H.

2016-01-01

Regional ventilation in the injured lung is heterogeneous and frequency dependent, making it difficult to predict how an oscillatory flow waveform at a specified frequency will be distributed throughout the periphery. To predict the impact of mechanical heterogeneity on regional ventilation distribution and gas transport, we developed a computational model of distributed gas flow and CO2 elimination during oscillatory ventilation from 0.1 to 30 Hz. The model consists of a three-dimensional airway network of a canine lung, with heterogeneous parenchymal tissues to mimic effects of gravity and injury. Model CO2 elimination during single frequency oscillation was validated against previously published experimental data (Venegas JG, Hales CA, Strieder DJ, J Appl Physiol 60: 1025–1030, 1986). Simulations of gas transport demonstrated a critical transition in flow distribution at the resonant frequency, where the reactive components of mechanical impedance due to airway inertia and parenchymal elastance were equal. For frequencies above resonance, the distribution of ventilation became spatially clustered and frequency dependent. These results highlight the importance of oscillatory frequency in managing the regional distribution of ventilation and gas exchange in the heterogeneous lung. PMID:27763872

[Alveolar ventilation and recruitment under lung protective ventilation].

PubMed

Putensen, Christian; Muders, Thomas; Kreyer, Stefan; Wrigge, Hermann

2008-11-01

Goal of mechanical ventilation is to improve gas exchange and reduce work of breathing without contributing to further lung injury. Besides providing adequate EELV and thereby arterial oxygenation PEEP in addition to a reduction in tidal volume is required to prevent cyclic alveolar collapse and tidal recruitment and hence protective mechanical ventilation. Currently, there is no consensus if and if yes at which price alveolar recruitment with high airway pressures should be intended ("open up the lung"), or if it is more important to reduce the mechanical stress and strain to the lungs as much as possible ("keep the lung closed"). Potential of alveolar recruitment differs from patient to patient but also between lung regions. Potential for recruitment depends probably more on regional lung mechanics - especially on lung elastance - than on the underlying disease. Based on available data neither high PEEP nor other methods used for alveolar recruitment could demonstrate a survival benefit in patients with ARDS. These results may support an individualized titration of PEEP or other manoeuvres used for recruitment taking into consideration the regional effects. Bedside imaging techniques allowing titration of PEEP or other manoeuvres to prevent end-expiratory alveolar collapse (tidal recruitment) and inspiratory overinflation may be a promising development.

Postmortem ventilation in cases of penetrating gunshot and stab wounds to the chest.

PubMed

Germerott, Tanja; Preiss, Ulrich S; Ross, Steffen G; Thali, Michael J; Flach, Patricia M

2013-11-01

We sought to determine the effect of postmortem ventilation in combination with a suction pump in cases showing penetrating trauma to the chest with haemo- and/or pneumothorax, for better evaluation of the lungs in postmortem computed tomography (PMCT). The study included 6 subjects (1 female, 5 male; age 32-67years) with a penetrating gunshot or stab wound to the chest and consecutive pneumo- and/or haemothorax. The pneumo- and haemothorax were evacuated by a suction pump, and postmortem ventilation was applied using a home care ventilator. PMCT images with and without postmortem ventilation were compared, as well as the autopsy results. In three cases haemo- and pneumothorax was clearly reduced. Postmortem ventilation led to distinct re-expansion of the lungs in two cases, and to re-expansion of single lung lobes in two cases with shotgun injuries. No visible effect was seen in the remaining two cases, because of extensive destruction of lung tissue and blood aspiration. In two cases the injuries sustained in the individual lung lobes were successfully located during postmortem ventilation. The bullet channel was apparent in one case; in another case, injury of the pericardium became visible by generating pneumopericardium. The present method is capable of improving evaluation of the postmortem lung in the presence of single stab or gunshot wounds and if there is no severe destruction of the respiratory system and aspiration. Forensic autopsy should still be considered as the gold standard, although in some cases the present method might be helpful, especially where no autopsy is required. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

A randomized comparison of different ventilator strategies during thoracotomy for pulmonary resection.

PubMed

Maslow, Andrew D; Stafford, Todd S; Davignon, Kristopher R; Ng, Thomas

2013-07-01

Protective lung ventilation is reported to benefit patients with acute respiratory distress syndrome. It is not known whether protective lung ventilation is also beneficial to patients undergoing single-lung ventilation for elective pulmonary resection. In an institutional review board-approved prospective randomized trial, 34 patients undergoing elective pulmonary resection requiring single-lung ventilation were enrolled. Informed consent was obtained. Patients were randomized to 1 of 2 groups: (1) high tidal volume (Hi-TV) of 10 mL/kg, rate of 7 breaths/min, and zero positive end-expiratory pressure or (2) low tidal volume (Lo-TV) of 5 mL/kg, rate of 14 breaths/min, and 5 cmH2O positive end-expiratory pressure. Ventilator settings were continued during both double- and single-lung ventilation. Pulmonary functions, hemodynamics, and postoperative outcomes were recorded. Patient demographics, operative characteristics, intraoperative hemodynamics, and postoperative pain and sedation scores were similar between the 2 groups. During most time periods, airway pressures (peak and plateau) were significantly higher in the Hi-TV group; however, plateau pressures remained less than 30 cmH2O at all times for all patients. The Hi-TV group had significantly lower arterial carbon dioxide tension, less arterial carbon dioxide tension-end-tidal carbon dioxide gradient, lower alveolar dead space ratio, and higher dynamic pulmonary compliance. There were no differences in postoperative morbidity and hospital days between the 2 groups, but atelectasis scores on postoperative days 1 and 2 were lower in the Hi-TV group. The use of Hi-TV during single-lung ventilation for pulmonary resection resulted in no increase in morbidity and was associated with less hypercarbia, less dead space ventilation, better dynamic compliance, and less postoperative atelectasis. Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Incidence Proportion of Acute Cor Pulmonale in Patients with Acute Respiratory Distress Syndrome Subjected to Lung Protective Ventilation: A Systematic Review and Meta-analysis.

PubMed

Das, Saurabh Kumar; Choupoo, Nang Sujali; Saikia, Priyam; Lahkar, Amitabh

2017-06-01

Reported incidence of acute cor pulmonale (ACP) in patients with acute respiratory distress syndrome (ARDS) varies from 10% to 84%, despite being subjected to lung protective ventilation according to the current guidelines. The objective of this review is to find pooled cumulative incidence of ACP in patients with ARDS undergoing lung protective ventilation. We searched MEDLINE, EMBASE, Cochrane Library, KoreaMed, LILACS, and WHO Clinical Trial Registry. Cross-sectional or cohort studies were included if they reported or provided data that could be used to calculate the incidence proportion of ACP. Inverse variance heterogeneity (IVhet) and random effect model were used for the main outcome and measures. We included 16 studies encompassing 1661 patients. The cumulative incidence of ACP using IVhet analysis was 23% (95% confidence interval [CI] = 18%-28%) over 3 days of lung protective ventilation. Random effect analysis of 7 studies (1250 patients) revealed pooled odd ratio of mortality of 1.16 (95% CI = 0.80-1.67, P = 0.44) due to ACP. Patients with ARDS have a 23% risk of developing ACP with lung protective ventilation. Findings of this review indicate the need of updating existing guidelines for ventilating ARDS patients to incorporate right ventricle protective strategy.

Lung volume changes during cleaning of closed endotracheal suction catheters: a randomized crossover study using electrical impedance tomography.

PubMed

Corley, Amanda; Sharpe, Nicola; Caruana, Lawrence R; Spooner, Amy J; Fraser, John F

2014-04-01

Airway suctioning in mechanically ventilated patients is required to maintain airway patency. Closed suction catheters (CSCs) minimize lung volume loss during suctioning but require cleaning post-suction. Despite their widespread use, there is no published evidence examining lung volumes during CSC cleaning. The study objectives were to quantify lung volume changes during CSC cleaning and to determine whether these changes were preventable using a CSC with a valve in situ between the airway and catheter cleaning chamber. This prospective randomized crossover study was conducted in a metropolitan tertiary ICU. Ten patients mechanically ventilated via volume-controlled synchronized intermittent mandatory ventilation (SIMV-VC) and requiring manual hyperinflation (MHI) were included in this study. CSC cleaning was performed using 2 different brands of CSC (one with a valve [Ballard Trach Care 72, Kimberly-Clark, Roswell, Georgia] and one without [Portex Steri-Cath DL, Smiths Medical, Dublin, Ohio]). The maneuvers were performed during both SIMV-VC and MHI. Lung volume change was measured via impedance change using electrical impedance tomography. A mixed model was used to compare the estimated means. During cleaning of the valveless CSC, significant decreases in lung impedance occurred during MHI (-2563 impedance units, 95% CI 2213-2913, P < .001), and significant increases in lung impedance occurred during SIMV (762 impedance units, 95% CI 452-1072, P < .001). In contrast, cleaning of the CSC with a valve in situ resulted in non-significant lung volume changes and maintenance of normal ventilation during MHI and SIMV-VC, respectively (188 impedance units, 95% CI -136 to 511, P = .22; and 22 impedance units, 95% CI -342 to 299, P = .89). When there is no valve between the airway and suction catheter, cleaning of the CSC results in significant derangements in lung volume. Therefore, the presence of such a valve should be considered essential in preserving lung volumes and uninterrupted ventilation in mechanically ventilated patients.

Regional Lung Function Profiles of Stage I and III Lung Cancer Patients: An Evaluation for Functional Avoidance Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradskiy, Yevgeniy, E-mail: yevgeniy.vinogradskiy@ucdenver.edu; Schubert, Leah; Diot, Quentin

2016-07-15

Purpose: The development of clinical trials is underway to use 4-dimensional computed tomography (4DCT) ventilation imaging to preferentially spare functional lung in patients undergoing radiation therapy. The purpose of this work was to generate data to aide with clinical trial design by retrospectively characterizing dosimetric and functional profiles for patients with different stages of lung cancer. Methods and Materials: A total of 118 lung cancer patients (36% stage I and 64% stage III) from 2 institutions were used for the study. A 4DCT-ventilation map was calculated using the patient's 4DCT imaging, deformable image registration, and a density-change–based algorithm. To assessmore » each patient's spatial ventilation profile both quantitative and qualitative metrics were developed, including an observer-based defect observation and metrics based on the ventilation in each lung third. For each patient we used the clinical doses to calculate functionally weighted mean lung doses and metrics that assessed the interplay between the spatial location of the dose and high-functioning lung. Results: Both qualitative and quantitative metrics revealed a significant difference in functional profiles between the 2 stage groups (P<.01). We determined that 65% of stage III and 28% of stage I patients had ventilation defects. Average functionally weighted mean lung dose was 19.6 Gy and 5.4 Gy for stage III and I patients, respectively, with both groups containing patients with large spatial overlap between dose and high-function regions. Conclusion: Our 118-patient retrospective study found that 65% of stage III patients have regionally variant ventilation profiles that are suitable for functional avoidance. Our results suggest that regardless of disease stage, it is possible to have unique spatial interplay between dose and high-functional lung, highlighting the importance of evaluating the function of each patient and developing a personalized functional avoidance treatment approach.« less

Effect of PEEP and Tidal Volume on Ventilation Distribution and End-Expiratory Lung Volume: A Prospective Experimental Animal and Pilot Clinical Study

PubMed Central

Becher, Tobias; Schädler, Dirk; Pulletz, Sven; Freitag-Wolf, Sandra; Weiler, Norbert; Frerichs, Inéz

2013-01-01

Introduction Lung-protective ventilation aims at using low tidal volumes (VT) at optimum positive end-expiratory pressures (PEEP). Optimum PEEP should recruit atelectatic lung regions and avoid tidal recruitment and end-inspiratory overinflation. We examined the effect of VT and PEEP on ventilation distribution, regional respiratory system compliance (CRS), and end-expiratory lung volume (EELV) in an animal model of acute lung injury (ALI) and patients with ARDS by using electrical impedance tomography (EIT) with the aim to assess tidal recruitment and overinflation. Methods EIT examinations were performed in 10 anaesthetized pigs with normal lungs ventilated at 5 and 10 ml/kg body weight VT and 5 cmH2O PEEP. After ALI induction, 10 ml/kg VT and 10 cmH2O PEEP were applied. Afterwards, PEEP was set according to the pressure-volume curve. Animals were randomized to either low or high VT ventilation changed after 30 minutes in a crossover design. Ventilation distribution, regional CRS and changes in EELV were analyzed. The same measures were determined in five ARDS patients examined during low and high VT ventilation (6 and 10 (8) ml/kg) at three PEEP levels. Results In healthy animals, high compared to low VT increased CRS and ventilation in dependent lung regions implying tidal recruitment. ALI reduced CRS and EELV in all regions without changing ventilation distribution. Pressure-volume curve-derived PEEP of 21±4 cmH2O (mean±SD) resulted in comparable increase in CRS in dependent and decrease in non-dependent regions at both VT. This implied that tidal recruitment was avoided but end-inspiratory overinflation was present irrespective of VT. In patients, regional CRS differences between low and high VT revealed high degree of tidal recruitment and low overinflation at 3±1 cmH2O PEEP. Tidal recruitment decreased at 10±1 cmH2O and was further reduced at 15±2 cmH2O PEEP. Conclusions Tidal recruitment and end-inspiratory overinflation can be assessed by EIT-based analysis of regional CRS. PMID:23991138

Evaluation of Fractional Regional Ventilation Using 4D-CT and Effects of Breathing Maneuvers on Ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mistry, Nilesh N., E-mail: nmistry@som.umaryland.edu; Diwanji, Tejan; Shi, Xiutao

2013-11-15

Purpose: Current implementations of methods based on Hounsfield units to evaluate regional lung ventilation do not directly incorporate tissue-based mass changes that occur over the respiratory cycle. To overcome this, we developed a 4-dimensional computed tomography (4D-CT)-based technique to evaluate fractional regional ventilation (FRV) that uses an individualized ratio of tidal volume to end-expiratory lung volume for each voxel. We further evaluated the effect of different breathing maneuvers on regional ventilation. The results from this work will help elucidate the relationship between global and regional lung function. Methods and Materials: Eight patients underwent 3 sets of 4D-CT scans during 1more » session using free-breathing, audiovisual guidance, and active breathing control. FRV was estimated using a density-based algorithm with mass correction. Internal validation between global and regional ventilation was performed by use of the imaging data collected during the use of active breathing control. The impact of breathing maneuvers on FRV was evaluated comparing the tidal volume from 3 breathing methods. Results: Internal validation through comparison between the global and regional changes in ventilation revealed a strong linear correlation (slope of 1.01, R{sup 2} of 0.97) between the measured global lung volume and the regional lung volume calculated by use of the “mass corrected” FRV. A linear relationship was established between the tidal volume measured with the automated breathing control system and FRV based on 4D-CT imaging. Consistently larger breathing volumes were observed when coached breathing techniques were used. Conclusions: The technique presented improves density-based evaluation of lung ventilation and establishes a link between global and regional lung ventilation volumes. Furthermore, the results obtained are comparable with those of other techniques of functional evaluation such as spirometry and hyperpolarized-gas magnetic resonance imaging. These results were demonstrated on retrospective analysis of patient data, and further research using prospective data is under way to validate this technique against established clinical tests.« less

Susceptibility to ventilator induced lung injury is increased in senescent rats

PubMed Central

2013-01-01

Introduction The principal mechanisms of ventilator induced lung injury (VILI) have been investigated in numerous animal studies. However, prospective data on the effect of old age on VILI are limited. Under the hypothesis that susceptibility to VILI is increased in old age, we investigated the pulmonary and extrapulmonary effects of mechanical ventilation with high tidal volume (VT) in old compared to young adult animals. Interventions Old (19.1 ± 3.0 months) and young adult (4.4 ± 1.3 months) male Wistar rats were anesthetized and mechanically ventilated (positive end-expiratory pressure 5 cmH2O, fraction of inspired oxygen 0.4, respiratory rate 40/minute) with a tidal volume (VT) of either 8, 16 or 24 ml/kg for four hours. Respiratory and hemodynamic variables, including cardiac output, and markers of systemic inflammation were recorded throughout the ventilation period. Lung histology and wet-to-dry weight ratio, injury markers in lung lavage and respiratory system pressure-volume curves were assessed post mortem. Basic pulmonary characteristics were assessed in non-ventilated animals. Results Compared to young adult animals, high VT (24 ml/kg body weight) caused more lung injury in old animals as indicated by decreased oxygenation (arterial oxygen tension (PaO2): 208 ± 3 vs. 131 ± 20 mmHg; P <0.05), increased lung wet-to-dry-weight ratio (5.61 ± 0.29 vs. 7.52 ± 0.27; P <0.05), lung lavage protein (206 ± 52 mg/l vs. 1,432 ± 101; P <0.05) and cytokine (IL-6: 856 ± 448 vs. 3,283 ± 943 pg/ml; P <0.05) concentration. In addition, old animals ventilated with high VT had more systemic inflammation than young animals (IL-1β: 149 ± 44 vs. 272 ± 36 pg/ml; P <0.05 - young vs. old, respectively). Conclusions Ventilation with unphysiologically large tidal volumes is associated with more lung injury in old compared to young rats. Aggravated pulmonary and systemic inflammation is a key finding in old animals developing VILI. PMID:23710684

Mechanical ventilation in patients subjected to extracorporeal membrane oxygenation (ECMO).

PubMed

López Sanchez, M

2017-11-01

Mechanical ventilation (MV) is a crucial element in the management of acute respiratory distress syndrome (ARDS), because there is high level evidence that a low tidal volume of 6ml/kg (protective ventilation) improves survival. In these patients with refractory respiratory insufficiency, venovenous extracorporeal membrane oxygenation (ECMO) can be used. This salvage technique improves oxygenation, promotes CO 2 clearance, and facilitates protective and ultraprotective MV, potentially minimizing ventilation-induced lung injury. Although numerous trials have investigated different ventilation strategies in patients with ARDS, consensus is lacking on the optimal MV settings during venovenous ECMO. Although the concept of "lung rest" was introduced years ago, there are no evidence-based guidelines on its use in application to MV in patients supported by ECMO. How MV in ECMO patients can promote lung recovery and weaning from ventilation is not clear. The purpose of this review is to describe the ventilation strategies used during venovenous ECMO in clinical practice. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

The muscular basis of aerial ventilation of the primitive lung of Amia calva.

PubMed

Deyst, K A; Liem, K F

1985-02-01

Anatomical analysis, electromyography, pressure recordings, high-speed X-ray and light movies of the mechanism of air ventilation in Amia calva reveal that aerial ventilation proceeds by the action of a specialized pulse pump. The interhyoideus muscle is the dominant muscle being active during both the preparatory phase and the final, prolonged compressive phase during which new air is forced into the lung. Amia retains a relatively large residual volume in the lung and does not repeat inhalation. It often expels excess air from the buccal cavity after the lung has been fully reinflated. The pressure, kinematic and air flow patterns during air ventilation in Amia closely resemble those of the air breath in the lungfish Protopterus. We hypothesize that the basically similar electromyographic profiles of homologous muscles so characteristic for the air ventilation mechanism of Protopterus and Amia reflect a homologous anatomical as well as functional neuromuscular pattern, which has had a common and early evolutionary origin among the Teleostomi.

New operational technology of intrauterine ventilation the fetus lungs by breathing gas

NASA Astrophysics Data System (ADS)

Urakov, A. L.; Nikityuk, D. B.; Urakova, N. A.; Kasankin, A. A.; Chernova, L. V.; Dementiev, V. B.

2015-11-01

New operational technology for elimination intrauterine hypoxia and asphyxia of the fetus using endoscopic artificial ventilation lungs by respiratory gas was developed. For intrauterine ventilation of fetal lung it is proposed to enter into the uterus a special breathing mask and wear it on the head of the fetus using the original endoscopic technology. The breathing mask, developed by us is connected with external breathing apparatus with a hose. The device is called "intrauterine aqualung". Intrauterine aqualung includes a ventilator and breathing circuit with a special fold-out breathing mask that is put on inside the uterus on the head of fetus like a mesh hat. Controlled by ultrasound the technology of the introduction of the mask inside of the uterus through the natural opening in the cervix and technology of putting on the respiratory mask on the head of the fetus with its head previa were developed. The technology intrauterine ventilation of the fetus lungs by respiratory gas was developed.

Pulmonary atelectasis during low stretch ventilation: "open lung" versus "lung rest" strategy.

PubMed

Fanelli, Vito; Mascia, Luciana; Puntorieri, Valeria; Assenzio, Barbara; Elia, Vincenzo; Fornaro, Giancarlo; Martin, Erica L; Bosco, Martino; Delsedime, Luisa; Fiore, Tommaso; Grasso, Salvatore; Ranieri, V Marco

2009-03-01

Limiting tidal volume (VT) may minimize ventilator-induced lung injury (VILI). However, atelectasis induced by low VT ventilation may cause ultrastructural evidence of cell disruption. Apoptosis seems to be involved as protective mechanisms from VILI through the involvement of mitogen-activated protein kinases (MAPKs). We examined the hypothesis that atelectasis may influence the response to protective ventilation through MAPKs. Prospective randomized study. University animal laboratory. Adult male 129/Sv mice. Isolated, nonperfused lungs were randomized to VILI: VT of 20 mL/kg and positive end-expiratory pressure (PEEP) zero; low stretch/lung rest: VT of 6 mL/kg and 8-10 cm H2O of PEEP; low stretch/open lung: VT of 6 mL/kg, two recruitment maneuvers and 14-16 cm H2O of PEEP. Ventilator settings were adjusted using the stress index. Both low stretch strategies equally blunted the VILI-induced derangement of respiratory mechanics (static volume-pressure curve), lung histology (hematoxylin and eosin), and inflammatory mediators (interleukin-6, macrophage inflammatory protein-2 [enzyme-linked immunosorbent assay], and inhibitor of nuclear factor-kB[Western blot]). VILI caused nuclear swelling and membrane disruption of pulmonary cells (electron microscopy). Few pulmonary cells with chromatin condensation and fragmentation were seen during both low stretch strategies. However, although cell thickness during low stretch/open lung was uniform, low stretch/lung rest demonstrated thickening of epithelial cells and plasma membrane bleb formation. Compared with the low stretch/open lung, low stretch/lung rest caused a significant decrease in apoptotic cells (terminal deoxynucleotidyl transferase mediated deoxyuridine-triphosphatase nick end-labeling) and tissue expression of caspase-3 (Western blot). Both low stretch strategies attenuated the activation of MAPKs. Such reduction was larger during low stretch/open lung than during low stretch/lung rest (p < 0.001). Low stretch strategies provide similar attenuation of VILI. However, low stretch/lung rest strategy is associated to less apoptosis and more ultrastructural evidence of cell damage possibly through MAPKs-mediated pathway.

Core body temperature control by total liquid ventilation using a virtual lung temperature sensor.

PubMed

Nadeau, Mathieu; Micheau, Philippe; Robert, Raymond; Avoine, Olivier; Tissier, Renaud; Germim, Pamela Samanta; Vandamme, Jonathan; Praud, Jean-Paul; Walti, Herve

2014-12-01

In total liquid ventilation (TLV), the lungs are filled with a breathable liquid perfluorocarbon (PFC) while a liquid ventilator ensures proper gas exchange by renewal of a tidal volume of oxygenated and temperature-controlled PFC. Given the rapid changes in core body temperature generated by TLV using the lung has a heat exchanger, it is crucial to have accurate and reliable core body temperature monitoring and control. This study presents the design of a virtual lung temperature sensor to control core temperature. In the first step, the virtual sensor, using expired PFC to estimate lung temperature noninvasively, was validated both in vitro and in vivo. The virtual lung temperature was then used to rapidly and automatically control core temperature. Experimentations were performed using the Inolivent-5.0 liquid ventilator with a feedback controller to modulate inspired PFC temperature thereby controlling lung temperature. The in vivo experimental protocol was conducted on seven newborn lambs instrumented with temperature sensors at the femoral artery, pulmonary artery, oesophagus, right ear drum, and rectum. After stabilization in conventional mechanical ventilation, TLV was initiated with fast hypothermia induction, followed by slow posthypothermic rewarming for 1 h, then by fast rewarming to normothermia and finally a second fast hypothermia induction phase. Results showed that the virtual lung temperature was able to provide an accurate estimation of systemic arterial temperature. Results also demonstrate that TLV can precisely control core body temperature and can be favorably compared to extracorporeal circulation in terms of speed.

Pulmonary surfactant concentration during transition from high frequency oscillation to conventional mechanical ventilation.

PubMed

Dargaville, P A; South, M; McDougall, P N

1997-12-01

To test the hypothesis that conventional mechanical ventilation (CV) provides a greater stimulus to secretion of pulmonary surfactant than high frequency oscillatory ventilation (HFO). Sequential examination of surfactant indices in lung lavage fluid in a group of six infants with severe lung disease (group 1), ventilated with HFO and then converted back to CV as their lung disease recovered. A similar group of 10 infants (group 2) ventilated conventionally throughout the course of their illness were studied for comparison. In groups 1 and 2, two sequential tracheal aspirate samples were taken, the first once lung disease was noted to be improving, and the second 48-72 h later. Group 1 infants had converted from HFO to CV during this time. A marked increase in concentration of total surfactant phospholipid (PL) and disaturated phosphatidylcholine (DSPC) was seen in group 1 after transition from HFO to CV; the magnitude of this increase was significantly greater than that sequentially observed in group II (total PL: 9.4-fold increase in group 1 vs 1.8-fold in group 2, P = 0.006; DSPC: group 1 6.4-fold increase vs. group 2 1.7-fold, P = 0.02). These findings suggest that intermittent lung inflation during CV produces more secretion of surfactant phospholipid than continuous alveolar distension on HFO, and raise the possibility that conservation and additional maturation of surfactant elements may occur when the injured lung is ventilated with HFO.

A novel combination of the Arndt endobronchial blocker and the laryngeal mask airway ProSeal™ provides one-lung ventilation for thoracic surgery

PubMed Central

LI, QIONG; LI, PEIYING; XU, JIANGHUI; GU, HUAHUA; MA, QINYUN; PANG, LIEWEN; LIANG, WEIMIN

2014-01-01

In this study, the feasibility and performance of the combination of the Arndt endobronchial blocker and the laryngeal mask airway (LMA) ProSeal™ in airway establishment, ventilation, oxygenation and lung isolation was evaluated. Fifty-five patients undergoing general anesthesia for elective thoracic surgeries were randomly allocated to group Arndt (n=26) or group double-lumen tube (DLT; n=29). Data concerning post-operative airway morbidity, ease of insertion, hemodynamics, lung collapse, ventilators, oxygenation and ventilation were collected for analysis. Compared with group DLT, group Arndt showed a significantly attenuated hemodynamic response to intubation (blood pressure, 149±31 vs. 115±16 mmHg; heart rate, 86±15 vs. 68±15 bpm), less severe injuries to the bronchus (injury score, 1.4±0.2 vs. 0.4±0.1) and vocal cords (injury score, 1.3±0.2 vs. 0.6±0.1), and lower incidences of post-operative sore throat and hoarseness. Furthermore, the novel combination of the Arndt and the LMA ProSeal showed similar ease of airway establishment, comparable ventilation and oxygenation performance, and an analogous lung isolation effect to DLT. The novel combined use of the Arndt endobronchial blocker and the LMA ProSeal can serve as a promising alternative for thoracic procedures requiring one-lung ventilation. The less traumatic properties and equally ideal lung isolation are likely to promote its use in rapidly spreading minimally invasive thoracic surgeries. PMID:25289071

Regional physiology of ARDS.

PubMed

Gattinoni, Luciano; Tonetti, Tommaso; Quintel, Michael

2017-12-28

The acute respiratory distress (ARDS) lung is usually characterized by a high degree of inhomogeneity. Indeed, the same lung may show a wide spectrum of aeration alterations, ranging from completely gasless regions, up to hyperinflated areas. This inhomogeneity is normally caused by the presence of lung edema and/or anatomical variations, and is deeply influenced by the gravitational forces.For any given airway pressure generated by the ventilator, the pressure acting directly on the lung (i.e., the transpulmonary pressure or lung stress) is determined by two main factors: 1) the ratio between lung elastance and the total elastance of the respiratory system (which has been shown to vary widely in ARDS patients, between 0.2 and 0.8); and 2) the lung size. In severe ARDS, the ventilatable parenchyma is strongly reduced in size ('baby lung'); its resting volume could be as low as 300 mL, and the total inspiratory capacity could be reached with a tidal volume of 750-900 mL, thus generating lethal stress and strain in the lung. Although this is possible in theory, it does not explain the occurrence of ventilator-induced lung injury (VILI) in lungs ventilated with much lower tidal volumes. In fact, the ARDS lung contains areas acting as local stress multipliers and they could multiply the stress by a factor ~ 2, meaning that in those regions the transpulmonary pressure could be double that present in other parts of the same lung. These 'stress raisers' widely correspond to the inhomogenous areas of the ARDS lung and can be present in up to 40% of the lung.Although most of the literature on VILI concentrates on the possible dangers of tidal volume, mechanical ventilation in fact delivers mechanical power (i.e., energy per unit of time) to the lung parenchyma, which reacts to it according to its anatomical structure and pathophysiological status. The determinants of mechanical power are not only the tidal volume, but also respiratory rate, inspiratory flow, and positive end-expiratory pressure (PEEP). In the end, decreasing mechanical power, increasing lung homogeneity, and avoiding reaching the anatomical limits of the 'baby lung' should be the goals for safe ventilation in ARDS.

WE-AB-202-08: Feasibility of Single-Inhalation/Single-Energy Xenon CT for High-Resolution Imaging of Regional Lung Ventilation in Humans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pinkham, D; Schueler, E; Diehn, M

Purpose: To demonstrate the efficacy of a novel functional lung imaging method that utilizes single-inhalation, single-energy xenon CT (Xe-CT) lung ventilation scans, and to compare it against the current clinical standard, ventilation single-photon emission CT (V-SPECT). Methods: In an IRB-approved clinical study, 14 patients undergoing thoracic radiotherapy received two successive single inhalation, single energy (80keV) CT images of the entire lung using 100% oxygen and a 70%/30% xenon-oxygen mixture. A subset of ten patients also received concurrent SPECT ventilation scans. Anatomic reproducibility between the two scans was achieved using a custom video biofeedback apparatus. The CT images were registered tomore » each other by deformable registration, and a calculated difference image served as surrogate xenon ventilation map. Both lungs were partitioned into twelve sectors, and a sector-wise correlation was performed between the xenon and V-SPECT scans. A linear regression model was developed with forced expiratory volume (FEV) as a predictor and the coefficient of variation (CoV) as the outcome. Results: The ventilation comparison for five of the patients had either moderate to strong Pearson correlation coefficients (0.47 to 0.69, p<0.05). Of these, four also had moderate to strong Spearman correlation coefficients (0.46 to 0.80, p<0.03). The patients with the strongest correlation had clear regional ventilation deficits. The patient comparisons with the weakest correlations had more homogeneous ventilation distributions, and those patients also had diminished lung function as assessed by spirometry. Analysis of the relationship between CoV and FEV yielded a non-significant trend toward negative correlation (Pearson coefficient −0.60, p<0.15). Conclusion: Significant correlations were found between the Xe-CT and V-SPECT ventilation imagery. The results from this small cohort of patients indicate that single inhalation, single energy Xe-CT has the potential to quantify regional lung ventilation volumetrically with high resolution using widely accessible radiologic equipment. Bill Loo and Peter Maxim are founders of TibaRay, Inc. Bill Loo is also a board member. Bill Loo and Peter Maxim have received research grants from Varian Medical Systems, Inc. and RaySearch Laboratory.« less

Physiology in Medicine: Understanding dynamic alveolar physiology to minimize ventilator-induced lung injury.

PubMed

Nieman, Gary F; Satalin, Josh; Kollisch-Singule, Michaela; Andrews, Penny; Aiash, Hani; Habashi, Nader M; Gatto, Louis A

2017-06-01

Acute respiratory distress syndrome (ARDS) remains a serious clinical problem with the main treatment being supportive in the form of mechanical ventilation. However, mechanical ventilation can be a double-edged sword: if set improperly, it can exacerbate the tissue damage caused by ARDS; this is known as ventilator-induced lung injury (VILI). To minimize VILI, we must understand the pathophysiologic mechanisms of tissue damage at the alveolar level. In this Physiology in Medicine paper, the dynamic physiology of alveolar inflation and deflation during mechanical ventilation will be reviewed. In addition, the pathophysiologic mechanisms of VILI will be reviewed, and this knowledge will be used to suggest an optimal mechanical breath profile (MB P : all airway pressures, volumes, flows, rates, and the duration that they are applied at both inspiration and expiration) necessary to minimize VILI. Our review suggests that the current protective ventilation strategy, known as the "open lung strategy," would be the optimal lung-protective approach. However, the viscoelastic behavior of dynamic alveolar inflation and deflation has not yet been incorporated into protective mechanical ventilation strategies. Using our knowledge of dynamic alveolar mechanics (i.e., the dynamic change in alveolar and alveolar duct size and shape during tidal ventilation) to modify the MB P so as to minimize VILI will reduce the morbidity and mortality associated with ARDS. Copyright © 2017 the American Physiological Society.

Lung-protective ventilation initiated in the emergency department (LOV-ED): a study protocol for a quasi-experimental, before-after trial aimed at reducing pulmonary complications.

PubMed

Fuller, Brian M; Ferguson, Ian; Mohr, Nicholas M; Stephens, Robert J; Briscoe, Cristopher C; Kolomiets, Angelina A; Hotchkiss, Richard S; Kollef, Marin H

2016-04-11

In critically ill patients, acute respiratory distress syndrome (ARDS) and ventilator-associated conditions (VACs) are associated with increased mortality, survivor morbidity and healthcare resource utilisation. Studies conclusively demonstrate that initial ventilator settings in patients with ARDS, and at risk for it, impact outcome. No studies have been conducted in the emergency department (ED) to determine if lung-protective ventilation in patients at risk for ARDS can reduce its incidence. Since the ED is the entry point to the intensive care unit for hundreds of thousands of mechanically ventilated patients annually in the USA, this represents a knowledge gap in this arena. A lung-protective ventilation strategy was instituted in our ED in 2014. It aims to address the parameters in need of quality improvement, as demonstrated by our previous research: (1) prevention of volutrauma; (2) appropriate positive end-expiratory pressure setting; (3) prevention of hyperoxia; and (4) aspiration precautions. The lung-protective ventilation initiated in the emergency department (LOV-ED) trial is a single-centre, quasi-experimental before-after study testing the hypothesis that lung-protective ventilation, initiated in the ED, is associated with reduced pulmonary complications. An intervention cohort of 513 mechanically ventilated adult ED patients will be compared with over 1000 preintervention control patients. The primary outcome is a composite outcome of pulmonary complications after admission (ARDS and VACs). Multivariable logistic regression with propensity score adjustment will test the hypothesis that ED lung-protective ventilation decreases the incidence of pulmonary complications. Approval of the study was obtained prior to data collection on the first patient. As the study is a before-after observational study, examining the effect of treatment changes over time, it is being conducted with waiver of informed consent. This work will be disseminated by publication of full-length manuscripts, presentation in abstract form at major scientific meetings and data sharing with other investigators through academically established means. NCT02543554. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Changes in Regional Ventilation During Treatment and Dosimetric Advantages of CT Ventilation Image Guided Radiation Therapy for Locally Advanced Lung Cancer.

PubMed

Yamamoto, Tokihiro; Kabus, Sven; Bal, Matthieu; Bzdusek, Karl; Keall, Paul J; Wright, Cari; Benedict, Stanley H; Daly, Megan E

2018-05-04

Lung functional image guided radiation therapy (RT) that avoids irradiating highly functional regions has potential to reduce pulmonary toxicity following RT. Tumor regression during RT is common, leading to recovery of lung function. We hypothesized that computed tomography (CT) ventilation image-guided treatment planning reduces the functional lung dose compared to standard anatomic image-guided planning in 2 different scenarios with or without plan adaptation. CT scans were acquired before RT and during RT at 2 time points (16-20 Gy and 30-34 Gy) for 14 patients with locally advanced lung cancer. Ventilation images were calculated by deformable image registration of four-dimensional CT image data sets and image analysis. We created 4 treatment plans at each time point for each patient: functional adapted, anatomic adapted, functional unadapted, and anatomic unadapted plans. Adaptation was performed at 2 time points. Deformable image registration was used for accumulating dose and calculating a composite of dose-weighted ventilation used to quantify the lung accumulated dose-function metrics. The functional plans were compared with the anatomic plans for each scenario separately to investigate the hypothesis at a significance level of 0.05. Tumor volume was significantly reduced by 20% after 16 to 20 Gy (P = .02) and by 32% after 30 to 34 Gy (P < .01) on average. In both scenarios, the lung accumulated dose-function metrics were significantly lower in the functional plans than in the anatomic plans without compromising target volume coverage and adherence to constraints to critical structures. For example, functional planning significantly reduced the functional mean lung dose by 5.0% (P < .01) compared to anatomic planning in the adapted scenario and by 3.6% (P = .03) in the unadapted scenario. This study demonstrated significant reductions in the accumulated dose to the functional lung with CT ventilation image-guided planning compared to anatomic image-guided planning for patients showing tumor regression and changes in regional ventilation during RT. Copyright © 2018 Elsevier Inc. All rights reserved.

The role of high airway pressure and dynamic strain on ventilator-induced lung injury in a heterogeneous acute lung injury model.

PubMed

Jain, Sumeet V; Kollisch-Singule, Michaela; Satalin, Joshua; Searles, Quinn; Dombert, Luke; Abdel-Razek, Osama; Yepuri, Natesh; Leonard, Antony; Gruessner, Angelika; Andrews, Penny; Fazal, Fabeha; Meng, Qinghe; Wang, Guirong; Gatto, Louis A; Habashi, Nader M; Nieman, Gary F

2017-12-01

Acute respiratory distress syndrome causes a heterogeneous lung injury with normal and acutely injured lung tissue in the same lung. Improperly adjusted mechanical ventilation can exacerbate ARDS causing a secondary ventilator-induced lung injury (VILI). We hypothesized that a peak airway pressure of 40 cmH 2 O (static strain) alone would not cause additional injury in either the normal or acutely injured lung tissue unless combined with high tidal volume (dynamic strain). Pigs were anesthetized, and heterogeneous acute lung injury (ALI) was created by Tween instillation via a bronchoscope to both diaphragmatic lung lobes. Tissue in all other lobes was normal. Airway pressure release ventilation was used to precisely regulate time and pressure at both inspiration and expiration. Animals were separated into two groups: (1) over-distension + high dynamic strain (OD + H DS , n = 6) and (2) over-distension + low dynamic strain (OD + L DS , n = 6). OD was caused by setting the inspiratory pressure at 40 cmH 2 O and dynamic strain was modified by changing the expiratory duration, which varied the tidal volume. Animals were ventilated for 6 h recording hemodynamics, lung function, and inflammatory mediators followed by an extensive necropsy. In normal tissue (N T ), OD + L DS caused minimal histologic damage and a significant reduction in BALF total protein (p < 0.05) and MMP-9 activity (p < 0.05), as compared with OD + H DS . In acutely injured tissue (ALI T ), OD + L DS resulted in reduced histologic injury and pulmonary edema (p < 0.05), as compared with OD + H DS . Both N T and ALI T are resistant to VILI caused by OD alone, but when combined with a H DS , significant tissue injury develops.

WE-AB-BRA-06: 4DCT-Ventilation: A Novel Imaging Modality for Thoracic Surgical Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradskiy, Y; Jackson, M; Schubert, L

Purpose: The current standard-of-care imaging used to evaluate lung cancer patients for surgical resection is nuclear-medicine ventilation. Surgeons use nuclear-medicine images along with pulmonary function tests (PFT) to calculate percent predicted postoperative (%PPO) PFT values by estimating the amount of functioning lung that would be lost with surgery. 4DCT-ventilation is an emerging imaging modality developed in radiation oncology that uses 4DCT data to calculate lung ventilation maps. We perform the first retrospective study to assess the use of 4DCT-ventilation for pre-operative surgical evaluation. The purpose of this work was to compare %PPO-PFT values calculated with 4DCT-ventilation and nuclear-medicine imaging. Methods:more » 16 lung cancer patients retrospectively reviewed had undergone 4DCTs, nuclear-medicine imaging, and had Forced Expiratory Volume in 1 second (FEV1) acquired as part of a standard PFT. For each patient, 4DCT data sets, spatial registration, and a density-change based model were used to compute 4DCT-ventilation maps. Both 4DCT and nuclear-medicine images were used to calculate %PPO-FEV1 using %PPO-FEV1=pre-operative FEV1*(1-fraction of total ventilation of resected lung). Fraction of ventilation resected was calculated assuming lobectomy and pneumonectomy. The %PPO-FEV1 values were compared between the 4DCT-ventilation-based calculations and the nuclear-medicine-based calculations using correlation coefficients and average differences. Results: The correlation between %PPO-FEV1 values calculated with 4DCT-ventilation and nuclear-medicine were 0.81 (p<0.01) and 0.99 (p<0.01) for pneumonectomy and lobectomy respectively. The average difference between the 4DCT-ventilation based and the nuclear-medicine-based %PPO-FEV1 values were small, 4.1±8.5% and 2.9±3.0% for pneumonectomy and lobectomy respectively. Conclusion: The high correlation results provide a strong rationale for a clinical trial translating 4DCT-ventilation to the surgical domain. Compared to nuclear-medicine, 4DCT-ventilation is cheaper, does not require a radioactive contrast agent, provides a faster imaging procedure, and has improved spatial resolution. 4DCT-ventilation can reduce the cost and imaging time for patients while providing improved spatial accuracy and quantitative results for surgeons. YV discloses grant from State of Colorado.« less

SU-E-J-120: Comparing 4D CT Computed Ventilation to Lung Function Measured with Hyperpolarized Xenon-129 MRI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neal, B; Chen, Q

2015-06-15

Purpose: To correlate ventilation parameters computed from 4D CT to ventilation, profusion, and gas exchange measured with hyperpolarized Xenon-129 MRI for a set of lung cancer patients. Methods: Hyperpolarized Xe-129 MRI lung scans were acquired for lung cancer patients, before and after radiation therapy, measuring ventilation, perfusion, and gas exchange. In the standard clinical workflow, these patients also received 4D CT scans before treatment. Ventilation was computed from 4D CT using deformable image registration (DIR). All phases of the 4D CT scan were registered using a B-spline deformable registration. Ventilation at the voxel level was then computed for each phasemore » based on a Jacobian volume expansion metric, yielding phase sorted ventilation images. Ventilation based upon 4D CT and Xe-129 MRI were co-registered, allowing qualitative visual comparison and qualitative comparison via the Pearson correlation coefficient. Results: Analysis shows a weak correlation between hyperpolarized Xe-129 MRI and 4D CT DIR ventilation, with a Pearson correlation coefficient of 0.17 to 0.22. Further work will refine the DIR parameters to optimize the correlation. The weak correlation could be due to the limitations of 4D CT, registration algorithms, or the Xe-129 MRI imaging. Continued development will refine parameters to optimize correlation. Conclusion: Current analysis yields a minimal correlation between 4D CT DIR and Xe-129 MRI ventilation. Funding provided by the 2014 George Amorino Pilot Grant in Radiation Oncology at the University of Virginia.« less

Effects of intratracheal mesenchymal stromal cell therapy during recovery and resolution after ventilator-induced lung injury.

PubMed

Curley, Gerard F; Ansari, Bilal; Hayes, Mairead; Devaney, James; Masterson, Claire; Ryan, Aideen; Barry, Frank; O'Brien, Timothy; Toole, Daniel O'; Laffey, John G

2013-04-01

Mesenchymal stromal cells (MSCs) have been demonstrated to attenuate acute lung injury when delivered by intravenous or intratracheal routes. The authors aimed to determine the efficacy of and mechanism of action of intratracheal MSC therapy and to compare their efficacy in enhancing lung repair after ventilation-induced lung injury with intravenous MSC therapy. : After induction of anesthesia, rats were orotracheally intubated and subjected to ventilation-induced lung injury (respiratory rate 18(-1) min, P insp 35 cm H2O,) to produce severe lung injury. After recovery, animals were randomized to receive: (1) no therapy, n = 4; (2) intratracheal vehicle (phosphate-buffered saline, 300 µl, n = 8); (3) intratracheal fibroblasts (4 × 10 cells, n = 8); (4) intratracheal MSCs (4 × 10(6) cells, n = 8); (5) intratracheal conditioned medium (300 µl, n = 8); or (6) intravenous MSCs (4 × 10(6) cells, n = 4). The extent of recovery after acute lung injury and the inflammatory response was assessed after 48 h. Intratracheal MSC therapy enhanced repair after ventilation-induced lung injury, improving arterial oxygenation (mean ± SD, 146 ± 3.9 vs. 110.8 ± 21.5 mmHg), restoring lung compliance (1.04 ± 0.11 vs. 0.83 ± 0.06 ml · cm H2O(-1)), reducing total lung water, and decreasing lung inflammation and histologic injury compared with control. Intratracheal MSC therapy attenuated alveolar tumor necrosis factor-α (130 ± 43 vs. 488 ± 211 pg · ml(-1)) and interleukin-6 concentrations (138 ± 18 vs. 260 ± 82 pg · ml(-1)). The efficacy of intratracheal MSCs was comparable with intravenous MSC therapy. Intratracheal MSCs seemed to act via a paracine mechanism, with conditioned MSC medium also enhancing lung repair after injury. Intratracheal MSC therapy enhanced recovery after ventilation-induced lung injury via a paracrine mechanism, and was as effective as intravenous MSC therapy.

Pathogenetic Significance of Biological Markers of Ventilator-Associated Lung Injury in Experimental and Clinical Studies*

PubMed Central

Frank, James A.; Parsons, Polly E.; Matthay, Michael A.

2009-01-01

For patients with acute lung injury, positive pressure mechanical ventilation is life saving. However, considerable experimental and clinical data have demonstrated that how clinicians set the tidal volume, positive end-expiratory pressure, and plateau airway pressure influences lung injury severity and patient outcomes including mortality. In order to better identify ventilator-associated lung injury (VALI), clinical investigators have sought to measure blood-borne and airspace biological markers of VALI. At the same time, several laboratory-based studies have focused on biological markers of inflammation and organ injury in experimental models in order to clarify the mechanisms of ventilator-induced lung injury (VILI) and VALI. This review summarizes data on biological markers of VALI and VILI from both clinical and experimental studies with an emphasis on markers identified in patients and in the experimental setting. This analysis suggests that measurement of some of these biological markers may be of value in diagnosing VALI and in understanding its pathogenesis. PMID:17167015

WE-AB-202-06: Correlating Lung CT HU with Transformation-Based and Xe-CT Derived Ventilation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, K; Patton, T; Bayouth, J

Purpose: Regional lung ventilation is useful to reduce radiation-induced function damage during lung cancer radiation therapy. Recently a new direct HU (Hounsfield unit)-based method was proposed to estimate the ventilation potential without image registration. The purpose of this study is to examine if there is a functional dependence between HU values and transformation-based or Xe-CT derived ventilation. Methods: 4DCT images acquired from 13 patients prior to radiation therapy and 4 mechanically ventilated sheep subjects which also have associated Xe-CT images were used for this analysis. Transformation-based ventilation was computed using Jacobian determinant of the transformation field between peak-exhale and peak-inhalemore » 4DCT images. Both transformation and Xe-CT derived ventilation was computed for each HU bin. Color scatter plot and cumulative histogram were used to compare and validate the direct HU-based method. Results: There was little change of the center and shape of the HU histograms between free breathing CT and 4DCT average, with or without smoothing, and between the repeated 4DCT scans. HU of −750 and −630 were found to have the greatest transformation-based ventilation for human and sheep subjects, respectively. Maximum Xe-CT derived ventilation was found to locate at HU of −600 in sheep subjects. The curve between Xe-CT ventilation and HU was noisy for tissue above HU −400, possibly due to less intensity change of Xe gas during wash-out and wash-in phases. Conclusion: Both transformation-based and Xe-CT ventilation demonstrated that lung tissues with HU values in the range of (-750, −600) HU have the maximum ventilation potential. The correlation between HU and ventilation suggests that HU might be used to help guide the ventilation calculation and make it more robust to noise and image registration errors. Research support from NIH grants CA166703 and CA166119 and a gift from Roger Koch.« less

[Aerosolized gadolinium-DTPA for demonstration of pulmonary ventilation in magnetic resonance tomography].

PubMed

Haage, P; Adam, G; Misselwitz, B; Karaagac, S; Pfeffer, J G; Glowinski, A; Döhmen, S; Tacke, J; Günther, R W

2000-04-01

Magnetic resonance assessment of lung ventilation with aerosolized Gd-DTPA. Eleven experimental procedures were carried out in a domestic pig model. The intubated pigs were aerosolized for 30 minutes with an aqueous formulation of Gd-DTPA. The contrast agent aerosol was generated by a small particle aerosol generator. Imaging was performed on a 1.5 T MR imager using a T1-weighted turbo spin echo sequence with respiratory gating (TR 141 ms, TE 8.5 ms, 6 averages, slice thickness 10 mm). Pulmonary signal intensities before and after ventilation were measured in peripheral portions of both lungs. Immediately after ventilation with aerosolized Gd-DTPA, the signal intensity in both lungs increased significantly in all animals with values up to 237% above baseline (mean 139% +/- 48%), but with in some cases considerable regional intra- and interindividual intensity differences. Distinctive parenchymal enhancement was readily visualized in all eleven cases with good spatial resolution. The presented data indicate that Gd-DTPA in aerosolized form can be used to demonstrate pulmonary ventilation in large animals with lung volumes comparable to man. Further experimental trials are necessary to improve reproducibility and to define the scope of this method for depicting lung disease.

Accidental entrapment of an endo-bronchial blocker tip by a surgical stapler during selective ventilation for lung lobectomy in a dog.

PubMed

Levionnois, Olivier L; Bergadano, Alessandra; Schatzmann, Urs

2006-01-01

To describe the use of an endobronchial blocker (EBB) and to perform selective ventilation during pulmonary lobe resection via thoracotomy in a dog and report its accidental stapling in the resection site. Clinical case report. One female dog with a suspected abscess or neoplasia of the right caudal pulmonary lobe. One-lung ventilation was performed using a wire-guided EBB to seal the contaminated parenchyma and facilitate surgical access. The affected lung parenchyma was resected and the resection site was closed with staples. Lobar resection was performed successfully, but the loop of the EBB guide wire was inadvertently entrapped in the staple line of the lobectomy. Staples were removed to release the wire loop, and the resulting air leak caused loss of ventilation control until the parenchyma was re-sealed. We recommend removing the wire guide associate with the EBB after successful lung separation to avoid accidents that could have life-threatening consequences if not recognized. One-lung ventilation is useful to isolate healthy parenchyma from diseased parenchyma during lobectomy. Anesthesiologists and surgeons need to be aware of the potential complications associated with use of EBB.

Bench performance of ventilators during simulated paediatric ventilation.

PubMed

Park, M A J; Freebairn, R C; Gomersall, C D

2013-05-01

This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2.

Mechanical ventilation during extracorporeal membrane oxygenation.

PubMed

Schmidt, Matthieu; Pellegrino, Vincent; Combes, Alain; Scheinkestel, Carlos; Cooper, D Jamie; Hodgson, Carol

2014-01-21

The timing of extracorporeal membrane oxygenation (ECMO) initiation and its outcome in the management of respiratory and cardiac failure have received considerable attention, but very little attention has been given to mechanical ventilation during ECMO. Mechanical ventilation settings in non-ECMO studies have been shown to have an effect on survival and may also have contributed to a treatment effect in ECMO trials. Protective lung ventilation strategies established for non-ECMO-supported respiratory failure patients may not be optimal for more severe forms of respiratory failure requiring ECMO support. The influence of positive end-expiratory pressure on the reduction of the left ventricular compliance may be a matter of concern for patients receiving ECMO support for cardiac failure. The objectives of this review were to describe potential mechanisms for lung injury during ECMO for respiratory or cardiac failure, to assess the possible benefits from the use of ultra-protective lung ventilation strategies and to review published guidelines and expert opinions available on mechanical ventilation-specific management of patients requiring ECMO, including mode and ventilator settings. Articles were identified through a detailed search of PubMed, Ovid, Cochrane databases and Google Scholar. Additional references were retrieved from the selected studies. Growing evidence suggests that mechanical ventilation settings are important in ECMO patients to minimize further lung damage and improve outcomes. An ultra-protective ventilation strategy may be optimal for mechanical ventilation during ECMO for respiratory failure. The effects of airway pressure on right and left ventricular afterload should be considered during venoarterial ECMO support of cardiac failure. Future studies are needed to better understand the potential impact of invasive mechanical ventilation modes and settings on outcomes.

Mechanical ventilation during extracorporeal membrane oxygenation

PubMed Central

2014-01-01

The timing of extracorporeal membrane oxygenation (ECMO) initiation and its outcome in the management of respiratory and cardiac failure have received considerable attention, but very little attention has been given to mechanical ventilation during ECMO. Mechanical ventilation settings in non-ECMO studies have been shown to have an effect on survival and may also have contributed to a treatment effect in ECMO trials. Protective lung ventilation strategies established for non-ECMO-supported respiratory failure patients may not be optimal for more severe forms of respiratory failure requiring ECMO support. The influence of positive end-expiratory pressure on the reduction of the left ventricular compliance may be a matter of concern for patients receiving ECMO support for cardiac failure. The objectives of this review were to describe potential mechanisms for lung injury during ECMO for respiratory or cardiac failure, to assess the possible benefits from the use of ultra-protective lung ventilation strategies and to review published guidelines and expert opinions available on mechanical ventilation-specific management of patients requiring ECMO, including mode and ventilator settings. Articles were identified through a detailed search of PubMed, Ovid, Cochrane databases and Google Scholar. Additional references were retrieved from the selected studies. Growing evidence suggests that mechanical ventilation settings are important in ECMO patients to minimize further lung damage and improve outcomes. An ultra-protective ventilation strategy may be optimal for mechanical ventilation during ECMO for respiratory failure. The effects of airway pressure on right and left ventricular afterload should be considered during venoarterial ECMO support of cardiac failure. Future studies are needed to better understand the potential impact of invasive mechanical ventilation modes and settings on outcomes. PMID:24447458

Protective mechanical ventilation, why use it?

PubMed

Seiberlich, Emerson; Santana, Jonas Alves; Chaves, Renata de Andrade; Seiberlich, Raquel Carvalho

2011-01-01

Mechanical ventilation (MV) strategies have been modified over the last decades with a tendency for increasingly lower tidal volumes (VT). However, in patients without acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) the use of high VTs is still very common. Retrospective studies suggest that this practice can be related to mechanical ventilation-associated ALI. The objective of this review is to search for evidence to guide protective MV in patients with healthy lungs and to suggest strategies to properly ventilate lungs with ALI/ARDS. A review based on the main articles that focus on the use of strategies of mechanical ventilation was performed. Consistent studies to determine which would be the best way to ventilate a patient with healthy lungs are lacking. Expert recommendations and current evidence presented in this article indicate that the use of a VT lower than 10 mL.kg(-1), associated with positive end-expiratory pressure (PEEP) ≥ 5 cmH(2)O without exceeding a pressure plateau of 15 to 20 cmH(2)O could minimize alveolar stretching at the end of inspiration and avoid possible inflammation or alveolar collapse. Copyright © 2011 Elsevier Editora Ltda. All rights reserved.

Regional gas transport in the heterogeneous lung during oscillatory ventilation.

PubMed

Herrmann, Jacob; Tawhai, Merryn H; Kaczka, David W

2016-12-01

Regional ventilation in the injured lung is heterogeneous and frequency dependent, making it difficult to predict how an oscillatory flow waveform at a specified frequency will be distributed throughout the periphery. To predict the impact of mechanical heterogeneity on regional ventilation distribution and gas transport, we developed a computational model of distributed gas flow and CO 2 elimination during oscillatory ventilation from 0.1 to 30 Hz. The model consists of a three-dimensional airway network of a canine lung, with heterogeneous parenchymal tissues to mimic effects of gravity and injury. Model CO 2 elimination during single frequency oscillation was validated against previously published experimental data (Venegas JG, Hales CA, Strieder DJ, J Appl Physiol 60: 1025-1030, 1986). Simulations of gas transport demonstrated a critical transition in flow distribution at the resonant frequency, where the reactive components of mechanical impedance due to airway inertia and parenchymal elastance were equal. For frequencies above resonance, the distribution of ventilation became spatially clustered and frequency dependent. These results highlight the importance of oscillatory frequency in managing the regional distribution of ventilation and gas exchange in the heterogeneous lung. Copyright © 2016 the American Physiological Society.

Whole lung lavage with intermittent double lung ventilation. A modified technique for managing pulmonary alveolar proteinosis.

PubMed

Ahmed, Raees; Iqbal, Mobeen; Kashef, Sayed H; Almomatten, Mohammed I

2005-01-01

Whole lung lavage is still the most effective treatment for pulmonary alveolar proteinosis. We report a 21-year-old male diagnosed with pulmonary alveolar proteinosis by open lung biopsy and who underwent whole lung lavage with a modified technique. He showed significant improvement in clinical and functional parameters. The technique of intermittent double lung ventilation during lavage procedure keeps the oxygen saturation in acceptable limits in patients at risk for severe hypoxemia and allows the procedure to be completed in a single setting.

Optimal ventilation of the anesthetized pediatric patient.

PubMed

Feldman, Jeffrey M

2015-01-01

Mechanical ventilation of the pediatric patient is challenging because small changes in delivered volume can be a significant fraction of the intended tidal volume. Anesthesia ventilators have traditionally been poorly suited to delivering small tidal volumes accurately, and pressure-controlled ventilation has become used commonly when caring for pediatric patients. Modern anesthesia ventilators are designed to deliver small volumes accurately to the patient's airway by compensating for the compliance of the breathing system and delivering tidal volume independent of fresh gas flow. These technology advances provide the opportunity to implement a lung-protective ventilation strategy in the operating room based upon control of tidal volume. This review will describe the capabilities of the modern anesthesia ventilator and the current understanding of lung-protective ventilation. An optimal approach to mechanical ventilation for the pediatric patient is described, emphasizing the importance of using bedside monitors to optimize the ventilation strategy for the individual patient.

Protective ventilation reduces Pseudomonas aeruginosa growth in lung tissue in a porcine pneumonia model.

PubMed

Sperber, Jesper; Nyberg, Axel; Lipcsey, Miklos; Melhus, Åsa; Larsson, Anders; Sjölin, Jan; Castegren, Markus

2017-08-31

Mechanical ventilation with positive end expiratory pressure and low tidal volume, i.e. protective ventilation, is recommended in patients with acute respiratory distress syndrome. However, the effect of protective ventilation on bacterial growth during early pneumonia in non-injured lungs is not extensively studied. The main objectives were to compare two different ventilator settings on Pseudomonas aeruginosa growth in lung tissue and the development of lung injury. A porcine model of severe pneumonia was used. The protective group (n = 10) had an end expiratory pressure of 10 cm H 2 O and a tidal volume of 6 ml x kg -1 . The control group (n = 10) had an end expiratory pressure of 5 cm H 2 O and a tidal volume of 10 ml x kg -1 . 10 11 colony forming units of Pseudomonas aeruginosa were inoculated intra-tracheally at baseline, after which the experiment continued for 6 h. Two animals from each group received only saline, and served as sham animals. Lung tissue samples from each animal were used for bacterial cultures and wet-to-dry weight ratio measurements. The protective group displayed lower numbers of Pseudomonas aeruginosa (p < 0.05) in the lung tissue, and a lower wet-to-dry ratio (p < 0.01) than the control group. The control group deteriorated in arterial oxygen tension/inspired oxygen fraction, whereas the protective group was unchanged (p < 0.01). In early phase pneumonia, protective ventilation with lower tidal volume and higher end expiratory pressure has the potential to reduce the pulmonary bacterial burden and the development of lung injury.

The effects of exogenous surfactant administration on ventilation-induced inflammation in mouse models of lung injury.

PubMed

Puntorieri, Valeria; Hiansen, Josh Qua; McCaig, Lynda A; Yao, Li-Juan; Veldhuizen, Ruud A W; Lewis, James F

2013-11-20

Mechanical ventilation (MV) is an essential supportive therapy for acute lung injury (ALI); however it can also contribute to systemic inflammation. Since pulmonary surfactant has anti-inflammatory properties, the aim of the study was to investigate the effect of exogenous surfactant administration on ventilation-induced systemic inflammation. Mice were randomized to receive an intra-tracheal instillation of a natural exogenous surfactant preparation (bLES, 50 mg/kg) or no treatment as a control. MV was then performed using the isolated and perfused mouse lung (IPML) set up. This model allowed for lung perfusion during MV. In experiment 1, mice were exposed to mechanical ventilation only (tidal volume =20 mL/kg, 2 hours). In experiment 2, hydrochloric acid or air was instilled intra-tracheally four hours before applying exogenous surfactant and ventilation (tidal volume =5 mL/kg, 2 hours). For both experiments, exogenous surfactant administration led to increased total and functional surfactant in the treated groups compared to the controls. Exogenous surfactant administration in mice exposed to MV only did not affect peak inspiratory pressure (PIP), lung IL-6 levels and the development of perfusate inflammation compared to non-treated controls. Acid injured mice exposed to conventional MV showed elevated PIP, lung IL-6 and protein levels and greater perfusate inflammation compared to air instilled controls. Instillation of exogenous surfactant did not influence the development of lung injury. Moreover, exogenous surfactant was not effective in reducing the concentration of inflammatory cytokines in the perfusate. The data indicates that exogenous surfactant did not mitigate ventilation-induced systemic inflammation in our models. Future studies will focus on altering surfactant composition to improve its immuno-modulating activity.

Air Trapping on Chest CT Is Associated with Worse Ventilation Distribution in Infants with Cystic Fibrosis Diagnosed following Newborn Screening

PubMed Central

Hall, Graham L.; Logie, Karla M.; Parsons, Faith; Schulzke, Sven M.; Nolan, Gary; Murray, Conor; Ranganathan, Sarath; Robinson, Phil; Sly, Peter D.; Stick, Stephen M.

2011-01-01

Background In school-aged children with cystic fibrosis (CF) structural lung damage assessed using chest CT is associated with abnormal ventilation distribution. The primary objective of this analysis was to determine the relationships between ventilation distribution outcomes and the presence and extent of structural damage as assessed by chest CT in infants and young children with CF. Methods Data of infants and young children with CF diagnosed following newborn screening consecutively reviewed between August 2005 and December 2009 were analysed. Ventilation distribution (lung clearance index and the first and second moment ratios [LCI, M1/M0 and M2/M0, respectively]), chest CT and airway pathology from bronchoalveolar lavage were determined at diagnosis and then annually. The chest CT scans were evaluated for the presence or absence of bronchiectasis and air trapping. Results Matched lung function, chest CT and pathology outcomes were available in 49 infants (31 male) with bronchiectasis and air trapping present in 13 (27%) and 24 (49%) infants, respectively. The presence of bronchiectasis or air trapping was associated with increased M2/M0 but not LCI or M1/M0. There was a weak, but statistically significant association between the extent of air trapping and all ventilation distribution outcomes. Conclusion These findings suggest that in early CF lung disease there are weak associations between ventilation distribution and lung damage from chest CT. These finding are in contrast to those reported in older children. These findings suggest that assessments of LCI could not be used to replace a chest CT scan for the assessment of structural lung disease in the first two years of life. Further research in which both MBW and chest CT outcomes are obtained is required to assess the role of ventilation distribution in tracking the progression of lung damage in infants with CF. PMID:21886842

[Anesthesia for thoracoscopic laser ablation of bullae in a patient with severe bullous emphysema].

PubMed

Saito, Y; Hayashida, M; Arita, H; Hanaoka, K

1995-05-01

A 46-year-old male underwent laser-ablation of emphysematous bullae of the right lung via thoracoscope. For almost a year he had been bedridden because of severe dyspnea on exertion, in spite of medication and oxygen therapy. He also complained of orthopnea at rest and had suffered from body weight loss of 10 kg during the preceding year. Radiologic examination revealed emphysemotous lung with bilateral giant bullae. In spirogram, forced vital capacity in 1 second was markedly low (0.45 l, corresponding to 19% in %FVC1.0), vital capacity moderately depressed (2.41 l, 64%) and residual volume markedly elevated (5.85 l, 387%). Anesthesia was induced and maintained using the combination of thoracic-epidural anesthesia and intravenous anesthesia (midazolam and fentanyl). One lung ventilation (OLV) was used to facilitate thoracoscopic procedure. Mechanical ventilation was conducted at first with an anesthesia ventilator. As the duration of OLV was prolonged, however, the peak airway pressure increased, the tidal volume decreased and the value of percutaneous arterial hemoglobin saturation (SpO2) declined. In order to keep adequate oxygenation, brief periods of two lung ventilation (TLV) became necessary, in addition to the application of continuous positive airway pressure to the non-dependent lung. When ventilation was changed from volume-cycled ventilation to pressure-cycled and from using an anesthesia ventilator to a critical care type ventilator (Servo 900C), sufficient tidal volume was achieved with lower peak airway pressure, producing reasonable Spo2 value with much less frequent TLV. At the end of the surgery bronchopleural fistulae still persisted, with resultant air leak of about 50% of inspired tidal volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute native lung hyperinflation is not associated with poor outcomes after single lung transplant for emphysema.

PubMed

Weill, D; Torres, F; Hodges, T N; Olmos, J J; Zamora, M R

1999-11-01

Single-lung transplantation for emphysema may be complicated by acute native lung hyperinflation (ANLH) with hemodynamic and ventilatory compromise. Some groups advocate the routine use of independent lung ventilation, double-lung transplant, or right-lung transplant with or without contralateral lung volume reduction surgery in high-risk patients. The goal of this study was to determine the incidence of ANLH and identify its potential predictors. We reviewed 51 consecutive single-lung transplants for emphysema. Symptomatic ANLH was defined as mediastinal shift and diaphragmatic flattening on chest x-ray with hemodynamic or respiratory failure requiring cardiopressor agents or independent lung ventilation. Preoperative and postoperative physiologic and hemodynamic data were analyzed from both recipients and donors. Sixteen patients developed radiographic ANLH; 8 were symptomatic, 2 severely so. We could not identify high-risk patients before transplant by pulmonary function tests, predicted donor total lung capacity (TLC)/actual recipient TLC ratio, pulmonary artery pressures, or the side transplanted. There was a trend toward an increased incidence of symptomatic ANLH in patients with bullous emphysema on chest computed tomography, but this was accounted for primarily by patients with alpha1-antitrypsin deficiency (4/13 vs 4/38 with chronic obstructive pulmonary disease, P = 0.10). No patient required cardiopulmonary bypass or inhaled nitric oxide intraoperatively. Patients with acute native lung hyperinflation did not have increased reperfusion edema as measured by chest x-ray score or PaO2/F(I)O2 ratio. Compared to patients without ANLH, symptomatic patients had longer ventilator times (64.9+/-14.6 hours vs 40.4+/-3.9, P = 0.02, ANOVA) and longer lengths of stay (19.3+/-2.1 days vs 13.7+/-1.3, P = 0.07), but 30-day survival was 100%. Two symptomatic patients required independent lung ventilation or inhaled nitric oxide; the others were managed with decreased minute ventilation, early extubation, and cardiopressor agents. No patient required early lung volume reduction surgery or retransplantation. Acute native lung hyperinflation had no effect on FEV1 or 6-minute walk results at 1 year; survival at 1, 2, or 3 years; or the rate of acute rejection, infection, or bronchiolitis obliterans syndrome greater than grade 2. Acute native lung hyperinflation is common radiographically but is rarely clinically severe. Although there was a trend toward an increase in symptomatic ANLH in patients with bullous emphysema, a high-risk group could not be identified preoperatively. Our results do not support the routine use of bilateral lung transplant, the exclusive use of right single-lung transplant, simultaneous lung volume reduction surgery, or independent lung ventilation for patients with emphysema. Management strategies should be employed that limit overdistension of the native lung and lead to early extubation.

Hypoxic pulmonary vasoconstriction in reptiles: a comparative study of four species with different lung structures and pulmonary blood pressures.

PubMed

Skovgaard, Nini; Abe, Augusto S; Andrade, Denis V; Wang, Tobias

2005-11-01

Low O2 levels in the lungs of birds and mammals cause constriction of the pulmonary vasculature that elevates resistance to pulmonary blood flow and increases pulmonary blood pressure. This hypoxic pulmonary vasoconstriction (HPV) diverts pulmonary blood flow from poorly ventilated and hypoxic areas of the lung to more well-ventilated parts and is considered important for the local matching of ventilation to blood perfusion. In the present study, the effects of acute hypoxia on pulmonary and systemic blood flows and pressures were measured in four species of anesthetized reptiles with diverse lung structures and heart morphologies: varanid lizards (Varanus exanthematicus), caimans (Caiman latirostris), rattlesnakes (Crotalus durissus), and tegu lizards (Tupinambis merianae). As previously shown in turtles, hypoxia causes a reversible constriction of the pulmonary vasculature in varanids and caimans, decreasing pulmonary vascular conductance by 37 and 31%, respectively. These three species possess complex multicameral lungs, and it is likely that HPV would aid to secure ventilation-perfusion homogeneity. There was no HPV in rattlesnakes, which have structurally simple lungs where local ventilation-perfusion inhomogeneities are less likely to occur. However, tegu lizards, which also have simple unicameral lungs, did exhibit HPV, decreasing pulmonary vascular conductance by 32%, albeit at a lower threshold than varanids and caimans (6.2 kPa oxygen in inspired air vs. 8.2 and 13.9 kPa, respectively). Although these observations suggest that HPV is more pronounced in species with complex lungs and functionally divided hearts, it is also clear that other components are involved.

On the Potential Role of MRI Biomarkers of COPD to Guide Bronchoscopic Lung Volume Reduction.

PubMed

Adams, Colin J; Capaldi, Dante P I; Di Cesare, Robert; McCormack, David G; Parraga, Grace

2018-02-01

In patients with severe emphysema and poor quality of life, bronchoscopic lung volume reduction (BLVR) may be considered and guided based on lobar emphysema severity. In particular, x-ray computed tomography (CT) emphysema measurements are used to identify the most diseased and the second-most diseased lobes as BLVR targets. Inhaled gas magnetic resonance imaging (MRI) also provides chronic obstructive pulmonary disease (COPD) biomarkers of lobar emphysema and ventilation abnormalities. Our objective was to retrospectively evaluate CT and MRI biomarkers of lobar emphysema and ventilation in patients with COPD eligible for BLVR. We hypothesized that MRI would provide complementary biomarkers of emphysema and ventilation that help determine the most appropriate lung lobar targets for BLVR in patients with COPD. We retrospectively evaluated 22 BLVR-eligible patients from the Thoracic Imaging Network of Canada cohort (diffusing capacity of the lung for carbon monoxide = 37 ± 12% predicted , forced expiratory volume in 1 second = 34 ± 7% predicted , total lung capacity = 131 ± 17% predicted , and residual volume = 216 ± 36% predicted ). Lobar CT emphysema, measured using a relative area of <-950 Hounsfield units (RA 950 ) and MRI ventilation defect percent, was independently used to rank lung lobe disease severity. In 7 of 22 patients, there were different CT and MRI predictions of the most diseased lobe. In some patients, there were large ventilation defects in lobes not targeted by CT, indicative of a poorly ventilated lung. CT and MRI classification of the most diseased and the second-most diseased lobes showed a fair-to-moderate intermethod reliability (Cohen κ = 0.40-0.59). In this proof-of-concept retrospective analysis, quantitative MRI ventilation and CT emphysema measurements provided different BLVR targets in over 30% of the patients. The presence of large MRI ventilation defects in lobes next to CT-targeted lobes might also change the decision to proceed or to guide BLVR to a different lobar target. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

"Open lung ventilation optimizes pulmonary function during lung surgery".

PubMed

Downs, John B; Robinson, Lary A; Steighner, Michael L; Thrush, David; Reich, Richard R; Räsänen, Jukka O

2014-12-01

We evaluated an "open lung" ventilation (OV) strategy using low tidal volumes, low respiratory rate, low FiO2, and high continuous positive airway pressure in patients undergoing major lung resections. In this phase I pilot study, twelve consecutive patients were anesthetized using conventional ventilator settings (CV) and then OV strategy during which oxygenation and lung compliance were noted. Subsequently, a lung resection was performed. Data were collected during both modes of ventilation in each patient, with each patient acting as his own control. The postoperative course was monitored for complications. Twelve patients underwent open thoracotomies for seven lobectomies and five segmentectomies. The OV strategy provided consistent one-lung anesthesia and improved static compliance (40 ± 7 versus 25 ± 4 mL/cm H2O, P = 0.002) with airway pressures similar to CV. Postresection oxygenation (SpO2/FiO2) was better during OV (433 ± 11 versus 386 ± 15, P = 0.008). All postoperative chest x-rays were free of atelectasis or infiltrates. No patient required supplemental oxygen at any time postoperatively or on discharge. The mean hospital stay was 4 ± 1 d. There were no complications or mortality. The OV strategy, previously shown to have benefits during mechanical ventilation of patients with respiratory failure, proved safe and effective in lung resection patients. Because postoperative pulmonary complications may be directly attributable to the anesthetic management, adopting an OV strategy that optimizes lung mechanics and gas exchange may help reduce postoperative problems and improve overall surgical results. A randomized trial is planned to ascertain whether this technique will reduce postoperative pulmonary complications. Copyright © 2014 Elsevier Inc. All rights reserved.

Uniform background assumption produces misleading lung EIT images.

PubMed

Grychtol, Bartłomiej; Adler, Andy

2013-06-01

Electrical impedance tomography (EIT) estimates an image of conductivity change within a body from stimulation and measurement at body surface electrodes. There is significant interest in EIT for imaging the thorax, as a monitoring tool for lung ventilation. To be useful in this application, we require an understanding of if and when EIT images can produce inaccurate images. In this paper, we study the consequences of the homogeneous background assumption, frequently made in linear image reconstruction, which introduces a mismatch between the reference measurement and the linearization point. We show in simulation and experimental data that the resulting images may contain large and clinically significant errors. A 3D finite element model of thorax conductivity is used to simulate EIT measurements for different heart and lung conductivity, size and position, as well as different amounts of gravitational collapse and ventilation-associated conductivity change. Three common linear EIT reconstruction algorithms are studied. We find that the asymmetric position of the heart can cause EIT images of ventilation to show up to 60% undue bias towards the left lung and that the effect is particularly strong for a ventilation distribution typical of mechanically ventilated patients. The conductivity gradient associated with gravitational lung collapse causes conductivity changes in non-dependent lung to be overestimated by up to 100% with respect to the dependent lung. Eliminating the mismatch by using a realistic conductivity distribution in the forward model of the reconstruction algorithm strongly reduces these undesirable effects. We conclude that subject-specific anatomically accurate forward models should be used in lung EIT and extra care is required when analysing EIT images of subjects whose background conductivity distribution in the lungs is known to be heterogeneous or exhibiting large changes.

Chest wall restriction limits high airway pressure-induced lung injury in young rabbits.

PubMed

Hernandez, L A; Peevy, K J; Moise, A A; Parker, J C

1989-05-01

High peak inspiratory pressures (PIP) during mechanical ventilation can induce lung injury. In the present study we compare the respective roles of high tidal volume with high PIP in intact immature rabbits to determine whether the increase in capillary permeability is the result of overdistension of the lung or direct pressure effects. New Zealand White rabbits were assigned to one of three protocols, which produced different degrees of inspiratory volume limitation: intact closed-chest animals (CC), closed-chest animals with a full-body plaster cast (C), and isolated excised lungs (IL). The intact animals were ventilated at 15, 30, or 45 cmH2O PIP for 1 h, and the lungs of the CC and C groups were placed in an isolated lung perfusion system. Microvascular permeability was evaluated using the capillary filtration coefficient (Kfc). Base-line Kfc for isolated lungs before ventilation was 0.33 +/- 0.31 ml.min-1.cmH2O-1.100g-1 and was not different from the Kfc in the CC group ventilated with 15 cmH2O PIP. Kfc increased by 850% after ventilation with only 15 cmH2O PIP in the unrestricted IL group, and in the CC group Kfc increased by 31% after 30 cmH2O PIP and 430% after 45 cmH2O PIP. Inspiratory volume limitation by the plaster cast in the C group prevented any significant increase in Kfc at the PIP values used. These data indicate that volume distension of the lung rather than high PIP per se produces microvascular damage in the immature rabbit lung.

Application of mid-frequency ventilation in an animal model of lung injury: a pilot study.

PubMed

Mireles-Cabodevila, Eduardo; Chatburn, Robert L; Thurman, Tracy L; Zabala, Luis M; Holt, Shirley J; Swearingen, Christopher J; Heulitt, Mark J

2014-11-01

Mid-frequency ventilation (MFV) is a mode of pressure control ventilation based on an optimal targeting scheme that maximizes alveolar ventilation and minimizes tidal volume (VT). This study was designed to compare the effects of conventional mechanical ventilation using a lung-protective strategy with MFV in a porcine model of lung injury. Our hypothesis was that MFV can maximize ventilation at higher frequencies without adverse consequences. We compared ventilation and hemodynamic outcomes between conventional ventilation and MFV. This was a prospective study of 6 live Yorkshire pigs (10 ± 0.5 kg). The animals were subjected to lung injury induced by saline lavage and injurious conventional mechanical ventilation. Baseline conventional pressure control continuous mandatory ventilation was applied with V(T) = 6 mL/kg and PEEP determined using a decremental PEEP trial. A manual decision support algorithm was used to implement MFV using the same conventional ventilator. We measured P(aCO2), P(aO2), end-tidal carbon dioxide, cardiac output, arterial and venous blood oxygen saturation, pulmonary and systemic vascular pressures, and lactic acid. The MFV algorithm produced the same minute ventilation as conventional ventilation but with lower V(T) (-1 ± 0.7 mL/kg) and higher frequency (32.1 ± 6.8 vs 55.7 ± 15.8 breaths/min, P < .002). There were no differences between conventional ventilation and MFV for mean airway pressures (16.1 ± 1.3 vs 16.4 ± 2 cm H2O, P = .75) even when auto-PEEP was higher (0.6 ± 0.9 vs 2.4 ± 1.1 cm H2O, P = .02). There were no significant differences in any hemodynamic measurements, although heart rate was higher during MFV. In this pilot study, we demonstrate that MFV allows the use of higher breathing frequencies and lower V(T) than conventional ventilation to maximize alveolar ventilation. We describe the ventilatory or hemodynamic effects of MFV. We also demonstrate that the application of a decision support algorithm to manage MFV is feasible. Copyright © 2014 by Daedalus Enterprises.

Effects of budesonide on the lung functions, inflammation and apoptosis in a saline-lavage model of acute lung injury.

PubMed

Mokra, D; Kosutova, P; Balentova, S; Adamkov, M; Mikolka, P; Mokry, J; Antosova, M; Calkovska, A

2016-12-01

Diffuse alveolar injury, edema, and inflammation are fundamental signs of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). Whereas the systemic administration of corticosteroids previously led to controversial results, this study evaluated if corticosteroids given intratracheally may improve lung functions and reduce edema formation, migration of cells into the lung and their activation in experimentally-induced ALI. In oxygen-ventilated rabbits, ALI was induced by repetitive saline lung lavage, until PaO2 decreased to < 26.7 kPa in FiO 2 1.0. Then, one group of animals was treated with corticosteroid budesonide (Pulmicort susp inh, AstraZeneca; 0.25 mg/kg) given intratracheally by means of inpulsion regime of high-frequency jet ventilation, while another group was non-treated, and both groups were oxygen-ventilated for following 5 hours. Another group of animals served as healthy controls. After sacrifice of animals, left lung was saline-lavaged and protein content was measured and cells in the lavage fluid were determined microscopically. Right lung tissue was used for estimation of edema formation (expressed as wet/dry weight ratio), for histomorphological investigation, immunohistochemical determination of apoptosis of lung cells, and for determination of markers of inflammation and lung injury (IL-1β, IL-6, IL-8, TNF-α, IFNγ, esRAGE, caspase-3) by ELISA methods. Levels of several cytokines were estimated also in plasma. Repetitive lung lavage worsened gas exchange, induced lung injury, inflammation and lung edema and increased apoptosis of lung epithelial cells. Budesonide reduced lung edema, cell infiltration into the lung and apoptosis of epithelial cells and decreased concentrations of proinflammatory markers in the lung and blood. These changes resulted in improved ventilation. Concluding, curative intratracheal treatment with budesonide alleviated lung injury, inflammation, apoptosis of lung epithelial cells and lung edema and improved lung functions in a lavage model of ALI. These findings suggest a potential of therapy with inhaled budesonide also for patients with ARDS.

Simultaneous magnetic resonance imaging of ventilation distribution and gas uptake in the human lung using hyperpolarized xenon-129

PubMed Central

Mugler, John P.; Altes, Talissa A.; Ruset, Iulian C.; Dregely, Isabel M.; Mata, Jaime F.; Miller, G. Wilson; Ketel, Stephen; Ketel, Jeffrey; Hersman, F. William; Ruppert, Kai

2010-01-01

Despite a myriad of technical advances in medical imaging, as well as the growing need to address the global impact of pulmonary diseases, such as asthma and chronic obstructive pulmonary disease, on health and quality of life, it remains challenging to obtain in vivo regional depiction and quantification of the most basic physiological functions of the lung—gas delivery to the airspaces and gas uptake by the lung parenchyma and blood—in a manner suitable for routine application in humans. We report a method based on MRI of hyperpolarized xenon-129 that permits simultaneous observation of the 3D distributions of ventilation (gas delivery) and gas uptake, as well as quantification of regional gas uptake based on the associated ventilation. Subjects with lung disease showed variations in gas uptake that differed from those in ventilation in many regions, suggesting that gas uptake as measured by this technique reflects such features as underlying pathological alterations of lung tissue or of local blood flow. Furthermore, the ratio of the signal associated with gas uptake to that associated with ventilation was substantially altered in subjects with lung disease compared with healthy subjects. This MRI-based method provides a way to quantify relationships among gas delivery, exchange, and transport, and appears to have significant potential to provide more insight into lung disease. PMID:21098267

Surfactant and pulmonary blood flow distributions following treatment of premature lambs with natural surfactant.

PubMed Central

Jobe, A; Ikegami, M; Jacobs, H; Jones, S

1984-01-01

Prematurely delivered lambs were treated with radiolabeled natural surfactant by either tracheal instillation at birth and before the onset of mechanical ventilation, or after 23 +/- 1 (+/- SE) min of mechanical ventilation. Right ventricular blood flow distributions, left ventricular outputs, and left-to-right ductal shunts were measured with radiolabeled microspheres. After sacrifice, the lungs of lambs receiving surfactant at birth inflated uniformly with constant distending pressure while the lungs of lambs treated after a period of ventilation had aerated, partially aerated, and atelectatic areas. All lungs were divided into pieces which were weighed and catalogued as to location. The amount of radiolabeled surfactant and microsphere-associated radioactivity in each piece of lung was quantified. Surfactant was relatively homogenously distributed to pieces of lung from lambs that were treated with surfactant at birth; 48% of lung pieces received amounts of surfactant within +/- 25% of the mean value. Surfactant was preferentially recovered from the aerated pieces of lungs of lambs treated after a period of mechanical ventilation, and the distribution of surfactant to these lungs was very nonhomogeneous. Right ventricular blood flow distributions to the lungs were quite homogeneous in both groups of lambs. However, in 8 of 12 lambs, pulmonary blood flow was preferentially directed away from those pieces of lung that received relatively large amounts of surfactant and toward pieces of lung that received less surfactant. This acute redirection of pulmonary blood flow distribution may result from the local changes in compliances within the lung following surfactant instillation. PMID:6546766

Iatrogenic pneumothorax related to mechanical ventilation

PubMed Central

Hsu, Chien-Wei; Sun, Shu-Fen

2014-01-01

Pneumothorax is a potentially lethal complication associated with mechanical ventilation. Most of the patients with pneumothorax from mechanical ventilation have underlying lung diseases; pneumothorax is rare in intubated patients with normal lungs. Tension pneumothorax is more common in ventilated patients with prompt recognition and treatment of pneumothorax being important to minimize morbidity and mortality. Underlying lung diseases are associated with ventilator-related pneumothorax with pneumothoraces occurring most commonly during the early phase of mechanical ventilation. The diagnosis of pneumothorax in critical illness is established from the patients’ history, physical examination and radiological investigation, although the appearances of a pneumothorax on a supine radiograph may be different from the classic appearance on an erect radiograph. For this reason, ultrasonography is beneficial for excluding the diagnosis of pneumothorax. Respiration-dependent movement of the visceral pleura and lung surface with respect to the parietal pleura and chest wall can be easily visualized with transthoracic sonography given that the presence of air in the pleural space prevents sonographic visualization of visceral pleura movements. Mechanically ventilated patients with a pneumothorax require tube thoracostomy placement because of the high risk of tension pneumothorax. Small-bore catheters are now preferred in the majority of ventilated patients. Furthermore, if there are clinical signs of a tension pneumothorax, emergency needle decompression followed by tube thoracostomy is widely advocated. Patients with pneumothorax related to mechanical ventilation who have tension pneumothorax, a higher acute physiology and chronic health evaluation II score or PaO2/FiO2 < 200 mmHg were found to have higher mortality. PMID:24834397

Four-dimensional optical coherence tomography imaging of total liquid ventilated rats

NASA Astrophysics Data System (ADS)

Kirsten, Lars; Schnabel, Christian; Gaertner, Maria; Koch, Edmund

2013-06-01

Optical coherence tomography (OCT) can be utilized for the spatially and temporally resolved visualization of alveolar tissue and its dynamics in rodent models, which allows the investigation of lung dynamics on the microscopic scale of single alveoli. The findings could provide experimental input data for numerical simulations of lung tissue mechanics and could support the development of protective ventilation strategies. Real four-dimensional OCT imaging permits the acquisition of several OCT stacks within one single ventilation cycle. Thus, the entire four-dimensional information is directly obtained. Compared to conventional virtual four-dimensional OCT imaging, where the image acquisition is extended over many ventilation cycles and is triggered on pressure levels, real four-dimensional OCT is less vulnerable against motion artifacts and non-reproducible movement of the lung tissue over subsequent ventilation cycles, which widely reduces image artifacts. However, OCT imaging of alveolar tissue is affected by refraction and total internal reflection at air-tissue interfaces. Thus, only the first alveolar layer beneath the pleura is visible. To circumvent this effect, total liquid ventilation can be carried out to match the refractive indices of lung tissue and the breathing medium, which improves the visibility of the alveolar structure, the image quality and the penetration depth and provides the real structure of the alveolar tissue. In this study, a combination of four-dimensional OCT imaging with total liquid ventilation allowed the visualization of the alveolar structure in rat lung tissue benefiting from the improved depth range beneath the pleura and from the high spatial and temporal resolution.

Extra corporeal membrane oxygenation to facilitate lung protective ventilation and prevent ventilator-induced lung injury in severe Pneumocystis pneumonia with pneumomediastinum: a case report and short literature review.

PubMed

Ali, Husain Shabbir; Hassan, Ibrahim Fawzy; George, Saibu

2016-04-14

Pulmonary infections caused by Pneumocystis jirovecii in immunocompromised host can be associated with cysts, pneumatoceles and air leaks that can progress to pneumomediastinum and pneumothoraxes. In such cases, it can be challenging to maintain adequate gas exchange by conventional mechanical ventilation and at the same time prevent further ventilator-induced lung injury. We report a young HIV positive male with poorly compliant lungs and pneumomediastinum secondary to severe Pneumocystis infection, rescued with veno-venous extra corporeal membrane oxygenation (V-V ECMO). A 26 year old male with no significant past medical history was admitted with fever, cough and shortness of breath. He initially required non-invasive ventilation for respiratory failure. However, his respiratory function progressively deteriorated due to increasing pulmonary infiltrates and development of pneumomediastinum, eventually requiring endotracheal intubation and invasive ventilation. Despite attempts at optimizing gas exchange by ventilatory maneuvers, patients' pulmonary parameters worsened necessitating rescue ECMO therapy. The introduction of V-V ECMO facilitated the use of ultra-protective lung ventilation and prevented progression of pneumomediastinum, maintaining optimal gas exchange. It allowed time for the antibiotics to show effect and pulmonary parenchyma to heal. Further diagnostic workup revealed Pneumocystis jirovecii as the causative organism for pneumonia and serology confirmed Human Immunodeficiency Virus infection. Patient was successfully treated with appropriate antimicrobials and de-cannulated after six days of ECMO support. ECMO was an effective salvage therapy in HIV positive patient with an otherwise fatal respiratory failure due to Pneumocystis pneumonia and air leak syndrome.

A perfluorochemical loss/restoration (L/R) system for tidal liquid ventilation.

PubMed

Libros, R; Philips, C M; Wolfson, M R; Shaffer, T H

2000-01-01

Tidal liquid ventilation is the transport of dissolved respiratory gases via volume exchange of perfluorochemical (PFC) liquid to and from the PFC-filled lung. All gas-liquid surface tension is eliminated, increasing compliance and providing lung protection due to lower inflation pressures. Tidal liquid ventilation is achieved by cycling fluid from a reservoir to and from the lung by a ventilator. Current approaches are microprocessor-based with feedback control. During inspiration, warmed oxygenated PFC liquid is pumped from a fluid reservoir/gas exchanger into the lung. PFC fluid is conserved by condensing (60-80% efficiency) vapor in the expired gas. A feedback-control system was developed to automatically replace PFC lost due to condenser inefficiency. This loss/restoration (L/R) system consists of a PFC-vapor thermal detector (+/- 2.5%), pneumatics, amplifiers, a gas flow detector (+/- 1%), a PFC pump (+/- 5%), and a controller. Gravimetric studies of perflubron loss from a flask due to evaporation were compared with experimental L/R results and found to be within +/- 1.4%. In addition, when L/R studies were conducted with a previously reported liquid ventilation system over a four-hour period, the L/R system maintained system perflubron volume to within +/- 1% of prime volume and 11.5% of replacement volume, and the difference between experimental PFC loss and that of the L/R system was 1.8 mL/hr. These studies suggest that the PFC L/R system may have significant economic (appropriate dosing for PFC loss) as well as physiologic (maintenance of PFC inventory in the lungs and liquid ventilator) impact on liquid ventilation procedures.

A quasi-experimental, before-after trial examining the impact of an emergency department mechanical ventilator protocol on clinical outcomes and lung-protective ventilation in acute respiratory distress syndrome

PubMed Central

Fuller, Brian M.; Ferguson, Ian T.; Mohr, Nicholas M.; Drewry, Anne M.; Palmer, Christopher; Wessman, Brian T.; Ablordeppey, Enyo; Keeperman, Jacob; Stephens, Robert J.; Briscoe, Cristopher C.; Kolomiets, Angelina A.; Hotchkiss, Richard S.; Kollef, Marin H.

2017-01-01

Objective To evaluate the impact of an emergency department (ED) mechanical ventilation protocol on clinical outcomes and adherence to lung-protective ventilation in patients with acute respiratory distress syndrome (ARDS). Design Quasi-experimental, before-after trial. Setting ED and intensive care units (ICU) of an academic center. Patients Mechanically ventilated ED patients experiencing ARDS while in the ED or after admission to the ICU. Interventions An ED ventilator protocol which targeted parameters in need of quality improvement, as identified by prior work: 1) lung-protective tidal volume; 2) appropriate setting of positive end-expiratory pressure (PEEP); 3) oxygen weaning; and 4) head-of-bed elevation. Measurements and Main Results A total of 229 patients (186 pre-intervention group, 43 intervention group) were studied. In the ED, the intervention was associated with significant changes (P < 0.01 for all) in tidal volume, PEEP, respiratory rate, oxygen administration, and head-of-bed elevation. There was a reduction in ED tidal volume from 8.1 mL/kg PBW (7.0 – 9.1) to 6.4 mL/kg PBW (6.1 – 6.7), and an increase in lung-protective ventilation from 11.1% to 61.5%, P < 0.01. The intervention was associated with a reduction in mortality from 54.8% to 39.5% (OR 0.38, 95% CI 0.17 – 0.83, P = 0.02), and a 3.9 day increase in ventilator-free days, P = 0.01. Conclusions This before-after study of mechanically ventilated patients with ARDS demonstrates that implementing a mechanical ventilator protocol in the ED is feasible, and associated with improved clinical outcomes. PMID:28157140

A Quasi-Experimental, Before-After Trial Examining the Impact of an Emergency Department Mechanical Ventilator Protocol on Clinical Outcomes and Lung-Protective Ventilation in Acute Respiratory Distress Syndrome.

PubMed

Fuller, Brian M; Ferguson, Ian T; Mohr, Nicholas M; Drewry, Anne M; Palmer, Christopher; Wessman, Brian T; Ablordeppey, Enyo; Keeperman, Jacob; Stephens, Robert J; Briscoe, Cristopher C; Kolomiets, Angelina A; Hotchkiss, Richard S; Kollef, Marin H

2017-04-01

To evaluate the impact of an emergency department mechanical ventilation protocol on clinical outcomes and adherence to lung-protective ventilation in patients with acute respiratory distress syndrome. Quasi-experimental, before-after trial. Emergency department and ICUs of an academic center. Mechanically ventilated emergency department patients experiencing acute respiratory distress syndrome while in the emergency department or after admission to the ICU. An emergency department ventilator protocol which targeted variables in need of quality improvement, as identified by prior work: 1) lung-protective tidal volume, 2) appropriate setting of positive end-expiratory pressure, 3) oxygen weaning, and 4) head-of-bed elevation. A total of 229 patients (186 preintervention group, 43 intervention group) were studied. In the emergency department, the intervention was associated with significant changes (p < 0.01 for all) in tidal volume, positive end-expiratory pressure, respiratory rate, oxygen administration, and head-of-bed elevation. There was a reduction in emergency department tidal volume from 8.1 mL/kg predicted body weight (7.0-9.1) to 6.4 mL/kg predicted body weight (6.1-6.7) and an increase in lung-protective ventilation from 11.1% to 61.5%, p value of less than 0.01. The intervention was associated with a reduction in mortality from 54.8% to 39.5% (odds ratio, 0.38; 95% CI, 0.17-0.83; p = 0.02) and a 3.9 day increase in ventilator-free days, p value equals to 0.01. This before-after study of mechanically ventilated patients with acute respiratory distress syndrome demonstrates that implementing a mechanical ventilator protocol in the emergency department is feasible and associated with improved clinical outcomes.

Flow-controlled expiration: a novel ventilation mode to attenuate experimental porcine lung injury.

PubMed

Goebel, U; Haberstroh, J; Foerster, K; Dassow, C; Priebe, H-J; Guttmann, J; Schumann, S

2014-09-01

Whereas the effects of various inspiratory ventilatory modifications in lung injury have extensively been studied, those of expiratory ventilatory modifications are less well known. We hypothesized that the newly developed flow-controlled expiration (FLEX) mode provides a means of attenuating experimental lung injury. Experimental acute respiratory distress syndrome was induced by i.v. injection of oleic acid in 15 anaesthetized and mechanically ventilated pigs. After established lung injury ([Formula: see text]ratio <27 kPa), animals were randomized to either a control group receiving volume-controlled ventilation (VCV) or a treatment group receiving VCV with additional FLEX (VCV+FLEX). At predefined times, lung mechanics and oxygenation were assessed. At the end of the experiment, the pigs were killed, and bronchoalveolar fluid and lung biopsies were taken. Expression of inflammatory cytokines was analysed in lung tissue and bronchoalveolar fluid. Lung injury score was determined on the basis of stained tissue samples. Compared with the control group (VCV; n=8), the VCV+FLEX group (n=7) demonstrated greater dynamic lung compliance and required less PEEP at comparable [Formula: see text] (both P<0.05), had lower regional lung wet-to-dry ratios and lung injury scores (both P<0.001), and showed less thickening of alveolar walls (an indicator of interstitial oedema) and de novo migration of macrophages into lung tissue (both P<0.001). The newly developed FLEX mode is able to attenuate experimental lung injury. FLEX could provide a novel means of lung-protective ventilation. © The Author [2014]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Rationale and study design of PROVHILO - a worldwide multicenter randomized controlled trial on protective ventilation during general anesthesia for open abdominal surgery.

PubMed

Hemmes, Sabrine N T; Severgnini, Paolo; Jaber, Samir; Canet, Jaume; Wrigge, Hermann; Hiesmayr, Michael; Tschernko, Edda M; Hollmann, Markus W; Binnekade, Jan M; Hedenstierna, Göran; Putensen, Christian; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J

2011-05-06

Post-operative pulmonary complications add to the morbidity and mortality of surgical patients, in particular after general anesthesia >2 hours for abdominal surgery. Whether a protective mechanical ventilation strategy with higher levels of positive end-expiratory pressure (PEEP) and repeated recruitment maneuvers; the "open lung strategy", protects against post-operative pulmonary complications is uncertain. The present study aims at comparing a protective mechanical ventilation strategy with a conventional mechanical ventilation strategy during general anesthesia for abdominal non-laparoscopic surgery. The PROtective Ventilation using HIgh versus LOw positive end-expiratory pressure ("PROVHILO") trial is a worldwide investigator-initiated multicenter randomized controlled two-arm study. Nine hundred patients scheduled for non-laparoscopic abdominal surgery at high or intermediate risk for post-operative pulmonary complications are randomized to mechanical ventilation with the level of PEEP at 12 cmH(2)O with recruitment maneuvers (the lung-protective strategy) or mechanical ventilation with the level of PEEP at maximum 2 cmH(2)O without recruitment maneuvers (the conventional strategy). The primary endpoint is any post-operative pulmonary complication. The PROVHILO trial is the first randomized controlled trial powered to investigate whether an open lung mechanical ventilation strategy in short-term mechanical ventilation prevents against postoperative pulmonary complications. ISRCTN: ISRCTN70332574.

Mechanical ventilation during extracorporeal membrane oxygenation. An international survey.

PubMed

Marhong, Jonathan D; Telesnicki, Teagan; Munshi, Laveena; Del Sorbo, Lorenzo; Detsky, Michael; Fan, Eddy

2014-07-01

In patients with severe, acute respiratory failure undergoing venovenous extracorporeal membrane oxygenation (VV-ECMO), the optimal strategy for mechanical ventilation is unclear. Our objective was to describe ventilation practices used in centers registered with the Extracorporeal Life Support Organization (ELSO). We conducted an international cross-sectional survey of medical directors and ECMO program coordinators from all ELSO-registered centers. The survey was distributed using a commercial website that collected information on center characteristics, the presence of a mechanical ventilator protocol, ventilator settings, and weaning practices. E-mails were sent out to medical directors or coordinators at each ELSO center and their responses were pooled for analysis. We analyzed 141 (50%) individual responses from the 283 centers contacted across 28 countries. Only 27% of centers reported having an explicit mechanical ventilation protocol for ECMO patients. The majority of these centers (77%) reported "lung rest" to be the primary goal of mechanical ventilation, whereas 9% reported "lung recruitment" to be their ventilation strategy. A tidal volume of 6 ml/kg or less was targeted by 76% of respondents, and 58% targeted a positive end-expiratory pressure of 6-10 cm H2O while ventilating patients on VV-ECMO. Centers prioritized weaning VV-ECMO before mechanical ventilation. Although ventilation practices in patients supported by VV-ECMO vary across ELSO centers internationally, the majority of centers used a strategy that targeted lung-protective thresholds and prioritized weaning VV-ECMO over mechanical ventilation.

Ventilation distribution in rats: Part 2 – A comparison of electrical impedance tomography and hyperpolarised helium magnetic resonance imaging

PubMed Central

2012-01-01

Background Hyperpolarised helium MRI (He3 MRI) is a new technique that enables imaging of the air distribution within the lungs. This allows accurate determination of the ventilation distribution in vivo. The technique has the disadvantages of requiring an expensive helium isotope, complex apparatus and moving the patient to a compatible MRI scanner. Electrical impedance tomography (EIT) a non-invasive bedside technique that allows constant monitoring of lung impedance, which is dependent on changes in air space capacity in the lung. We have used He3MRI measurements of ventilation distribution as the gold standard for assessment of EIT. Methods Seven rats were ventilated in supine, prone, left and right lateral position with 70% helium/30% oxygen for EIT measurements and pure helium for He3 MRI. The same ventilator and settings were used for both measurements. Image dimensions, geometric centre and global in homogeneity index were calculated. Results EIT images were smaller and of lower resolution and contained less anatomical detail than those from He3 MRI. However, both methods could measure positional induced changes in lung ventilation, as assessed by the geometric centre. The global in homogeneity index were comparable between the techniques. Conclusion EIT is a suitable technique for monitoring ventilation distribution and inhomgeneity as assessed by comparison with He3 MRI. PMID:22966835

Variability in Usual Care Mechanical Ventilation for Pediatric Acute Respiratory Distress Syndrome: Time for a Decision Support Protocol?

PubMed

Newth, Christopher J L; Sward, Katherine A; Khemani, Robinder G; Page, Kent; Meert, Kathleen L; Carcillo, Joseph A; Shanley, Thomas P; Moler, Frank W; Pollack, Murray M; Dalton, Heidi J; Wessel, David L; Berger, John T; Berg, Robert A; Harrison, Rick E; Holubkov, Richard; Doctor, Allan; Dean, J Michael; Jenkins, Tammara L; Nicholson, Carol E

2017-11-01

Although pediatric intensivists philosophically embrace lung protective ventilation for acute lung injury and acute respiratory distress syndrome, we hypothesized that ventilator management varies. We assessed ventilator management by evaluating changes to ventilator settings in response to blood gases, pulse oximetry, or end-tidal CO2. We also assessed the potential impact that a pediatric mechanical ventilation protocol adapted from National Heart Lung and Blood Institute acute respiratory distress syndrome network protocols could have on reducing variability by comparing actual changes in ventilator settings to those recommended by the protocol. Prospective observational study. Eight tertiary care U.S. PICUs, October 2011 to April 2012. One hundred twenty patients (age range 17 d to 18 yr) with acute lung injury/acute respiratory distress syndrome. Two thousand hundred arterial and capillary blood gases, 3,964 oxygen saturation by pulse oximetry, and 2,757 end-tidal CO2 values were associated with 3,983 ventilator settings. Ventilation mode at study onset was pressure control 60%, volume control 19%, pressure-regulated volume control 18%, and high-frequency oscillatory ventilation 3%. Clinicians changed FIO2 by ±5 or ±10% increments every 8 hours. Positive end-expiratory pressure was limited at ~10 cm H2O as oxygenation worsened, lower than would have been recommended by the protocol. In the first 72 hours of mechanical ventilation, maximum tidal volume/kg using predicted versus actual body weight was 10.3 (8.5-12.9) (median [interquartile range]) versus 9.2 mL/kg (7.6-12.0) (p < 0.001). Intensivists made changes similar to protocol recommendations 29% of the time, opposite to the protocol's recommendation 12% of the time and no changes 56% of the time. Ventilator management varies substantially in children with acute respiratory distress syndrome. Opportunities exist to minimize variability and potentially injurious ventilator settings by using a pediatric mechanical ventilation protocol offering adequately explicit instructions for given clinical situations. An accepted protocol could also reduce confounding by mechanical ventilation management in a clinical trial.

MO-A-BRD-05: Evaluation of Composed Lung Ventilation with 4DCT and Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, K; Bayouth, J; Reinhardt, J

Purpose: Regional pulmonary function can be derived using fourdimensional computed tomography (4DCT) combined with deformable image registration. However, only peak inhale and exhale phases have been used thus far while the lung ventilation during intermediate phases is not considered. In our previous work, we have investigated the spatiotemporal heterogeneity of lung ventilation and its dependence on respiration effort. In this study, composed ventilation is introduced using all inspiration phases and compared to direct ventilation. Both methods are evaluated against Xe-CT derived ventilation. Methods: Using an in-house tissue volume preserving deformable image registration, unlike the direct ventilation method, which computes frommore » end expiration to end inspiration, Jacobian ventilation maps were computed from one inhale phase to the next and then composed from all inspiration steps. The two methods were compared in both patients prior to RT and mechanically ventilated sheep subjects. In addition, they wereassessed for the correlation with Xe-CT derived ventilation in sheep subjects. Annotated lung landmarks were used to evaluate the accuracy of original and composed deformation field. Results: After registration, the landmark distance for composed deformation field was always higher than that for direct deformation field (0IN to 100IN average in human: 1.03 vs 1.53, p=0.001, and in sheep: 0.80 vs0.94, p=0.009), and both increased with longer phase interval. Direct and composed ventilation maps were similar in both sheep (gamma pass rate 87.6) and human subjects (gamma pass rate 71.9),and showed consistent pattern from ventral to dorsal when compared to Xe-CT derived ventilation. Correlation coefficient between Xe-CT and composed ventilation was slightly better than the direct method but not significant (average 0.89 vs 0.85, p=0.135). Conclusion: More strict breathing control in sheep subjects may explain higher similarity between direct and composed ventilation. When compared to Xe-CT ventilation, no significant difference was found for the composed method. NIH Grant: R01 CA166703.« less

Home energy efficiency and radon related risk of lung cancer: modelling study

PubMed Central

Milner, James; Shrubsole, Clive; Das, Payel; Jones, Benjamin; Ridley, Ian; Chalabi, Zaid; Hamilton, Ian; Armstrong, Ben; Davies, Michael

2014-01-01

Objective To investigate the effect of reducing home ventilation as part of household energy efficiency measures on deaths from radon related lung cancer. Design Modelling study. Setting England. Intervention Home energy efficiency interventions, motivated in part by targets for reducing greenhouse gases, which entail reduction in uncontrolled ventilation in keeping with good practice guidance. Main outcome measures Modelled current and future distributions of indoor radon levels for the English housing stock and associated changes in life years due to lung cancer mortality, estimated using life tables. Results Increasing the air tightness of dwellings (without compensatory purpose-provided ventilation) increased mean indoor radon concentrations by an estimated 56.6%, from 21.2 becquerels per cubic metre (Bq/m3) to 33.2 Bq/m3. After the lag in lung cancer onset, this would result in an additional annual burden of 4700 life years lost and (at peak) 278 deaths. The increases in radon levels for the millions of homes that would contribute most of the additional burden are below the threshold at which radon remediation measures are cost effective. Fitting extraction fans and trickle ventilators to restore ventilation will help offset the additional burden but only if the ventilation related energy efficiency gains are lost. Mechanical ventilation systems with heat recovery may lower radon levels and the risk of cancer while maintaining the advantage of energy efficiency for the most airtight dwellings but there is potential for a major adverse impact on health if such systems fail. Conclusion Unless specific remediation is used, reducing the ventilation of dwellings will improve energy efficiency only at the expense of population wide adverse impact on indoor exposure to radon and risk of lung cancer. The implications of this and other consequences of changes to ventilation need to be carefully evaluated to ensure that the desirable health and environmental benefits of home energy efficiency are not compromised by avoidable negative impacts on indoor air quality. PMID:24415631

Gill and lung ventilation responses to steady-state aquatic hypoxia and hyperoxia in the bullfrog tadpole.

PubMed

West, N H; Burggren, W W

1982-02-01

Gill ventilation frequency (fG), the pressure amplitude (PBC) and stroke volume (VS) of buccal ventilation cycles, the frequency of air breaths (fL), water flow over the gills (VW), gill oxygen uptake (MGO2), oxygen utilization (U), and heart frequency (fH) have been measured in unanaesthetized, air breathing Rana catesbeiana tadpoles (stage XVI-XIX). The animals were unrestrained except for ECG leads or cannulae, and were able to surface voluntarily for air breathing. They were subjected to aquatic normoxia, hyperoxia and three levels of aquatic hypoxia, and their respiratory responses recorded in the steady state. The experiments were performed at 20 +/- 0.5 degrees C. In hyperoxia there was an absence of air breathing, and fG, PBC and VW fell from the normoxic values, while U increased, resulting in no significant change in MGO2. Animals in normoxia showed a very low fL which increased in progressively more hypoxic states. VW increased from the normoxic value in mild hypoxia (PO2 = 96 +/- 2 mm Hg), but fell, associated with a reduction in PBC, in moderate (PO2 = 41 +/- 1 mm Hg) and severe (PO2 = 21 +/- 3 mm Hg) hypoxia in the presence of lung ventilation. Gill MGO2 was not significantly different from the normoxic value in mild hypoxia but fell in moderate hypoxia, while in severe hypoxia oxygen was lost to the ventilating water from the blood perfusing the gills. There was no significant change in fH from the normoxic value in either hypoxia or hyperoxia. These data indicate, that in the bimodally breathing bullfrog tadpole, aquatic PO2 exerts a strong control over both gill and lung ventilation. Furthermore, there is an interaction between gill and lung ventilation such that the onset of a high frequency of lung ventilation in moderate and severe hypoxia promotes a suppression of gill ventilation cycles.

[The prevention and treatment of suppurative-inflammatory complications in the bronchopulmonary system during prolonged artificial ventilation].

PubMed

Mozhaev, G A; Tikhonovskiĭ, I Iu

1992-01-01

The use of physical methods, namely low frequency magnetic field in critically ill patients under respiratory therapy made it possible to prevent and in case of their development to effectively treat pyoinflammatory bronchopulmonary complications that accompany prolonged controlled lung ventilation. The results obtained were due to the elimination of an unfavourable effect of controlled lung ventilation on natural resistance and immune response of the respiratory tract because of normalization of physicochemical properties of the tracheobronchial tree secretion, enhanced functional capacities of phagocytes, repaired bonds between cellular and humoral local immunity in the lungs.

Heliox Improves Carbon Dioxide Removal during Lung Protective Mechanical Ventilation.

PubMed

Beurskens, Charlotte J; Brevoord, Daniel; Lagrand, Wim K; van den Bergh, Walter M; Vroom, Margreeth B; Preckel, Benedikt; Horn, Janneke; Juffermans, Nicole P

2014-01-01

Introduction. Helium is a noble gas with low density and increased carbon dioxide (CO2) diffusion capacity. This allows lower driving pressures in mechanical ventilation and increased CO2 diffusion. We hypothesized that heliox facilitates ventilation in patients during lung-protective mechanical ventilation using low tidal volumes. Methods. This is an observational cohort substudy of a single arm intervention study. Twenty-four ICU patients were included, who were admitted after a cardiac arrest and mechanically ventilated for 3 hours with heliox (50% helium; 50% oxygen). A fixed protective ventilation protocol (6 mL/kg) was used, with prospective observation for changes in lung mechanics and gas exchange. Statistics was by Bonferroni post-hoc correction with statistical significance set at P < 0.017. Results. During heliox ventilation, respiratory rate decreased (25 ± 4 versus 23 ± 5 breaths min(-1), P = 0.010). Minute volume ventilation showed a trend to decrease compared to baseline (11.1 ± 1.9 versus 9.9 ± 2.1 L min(-1), P = 0.026), while reducing PaCO2 levels (5.0 ± 0.6 versus 4.5 ± 0.6 kPa, P = 0.011) and peak pressures (21.1 ± 3.3 versus 19.8 ± 3.2 cm H2O, P = 0.024). Conclusions. Heliox improved CO2 elimination while allowing reduced minute volume ventilation in adult patients during protective mechanical ventilation.

Measurement of lung function using Electrical Impedance Tomography (EIT) during mechanical ventilation

NASA Astrophysics Data System (ADS)

Nebuya, Satoru; Koike, Tomotaka; Imai, Hiroshi; Noshiro, Makoto; Brown, Brian H.; Soma, Kazui

2010-04-01

The consistency of regional lung density measurements as estimated by Electrical Impedance Tomography (EIT), in eleven patients supported by a mechanical ventilator, was validated to verify the feasibility of its use in intensive care medicine. There were significant differences in regional lung densities between the normal lung and diseased lungs associated with pneumonia, atelectasis and pleural effusion (Steel-Dwass test, p < 0.05). Temporal changes in regional lung density of patients with atelectasis were observed to be in good agreement with the results of clinical diagnosis. These results indicate that it is feasible to obtain a quantitative value for regional lung density using EIT.

The protective effect of dopamine on ventilator-induced lung injury via the inhibition of NLRP3 inflammasome.

PubMed

Yang, Xiaomei; Sun, Xiaotong; Chen, Hongli; Xi, Guangmin; Hou, Yonghao; Wu, Jianbo; Liu, Dejie; Wang, Huanliang; Hou, Yuedong; Yu, Jingui

2017-04-01

Dopamine (DA), a neurotransmitter, was previously shown to have anti-inflammatory effects. However, its role in ventilator-induced lung injury (VILI) has not been explicitly demonstrated. This study aimed to investigate the therapeutic efficacy and molecular mechanisms of dopamine in VILI. Rats were treated with dopamine during mechanical ventilation. Afterwards, the influence of dopamine on histological changes, pulmonary edema, the lung wet/dry (W/D) ratio, myeloperoxidase (MPO) activity, polymorphonuclear(PMN)counts, inflammatory cytokine levels, and NLRP3 inflammasome protein expression were examined. Our results showed that dopamine significantly attenuated lung tissue injury, the lung W/D ratio, MPO activity and neutrophil infiltration. Moreover, it inhibited inflammatory cytokine levels in the Bronchoalveolar lavage fluid (BAL). In addition, dopamine significantly inhibited ventilation-induced NLRP3 activation. Our experimental findings demonstrate that dopamine exerted protective effects in VILI by alleviating the inflammatory response through inhibition of NLRP3 signaling pathways. The present study indicated that dopamine could be a potential effective therapeutic strategy for the treatment of VILI. Copyright © 2017 Elsevier B.V. All rights reserved.

Lung Volume Reduction Surgery for Respiratory Failure in Infants With Bronchopulmonary Dysplasia.

PubMed

Sohn, Bongyeon; Park, Samina; Park, In Kyu; Kim, Young Tae; Park, June Dong; Park, Sung-Hye; Kang, Chang Hyun

2018-04-01

Lung volume reduction surgery (LVRS) can be performed in patients with severe emphysematous disease. However, LVRS in pediatric patients has not yet been reported. Here, we report our experience with 2 cases of pediatric LVRS. The first patient was a preterm infant girl with severe bronchopulmonary dysplasia, pulmonary hypertension, and hypothyroidism. The emphysematous portion of the right lung was removed via sternotomy and right hemiclamshell incision. The patient was discharged on full-time home ventilator support for 3 months after the surgery. Since then, her respiratory function has improved continuously. She no longer needs oxygen supplementation or ventilator care. Her T-cannula was removed recently. The second patient was also a preterm infant girl with bronchopulmonary dysplasia. She was born with pulmonary hypertension and multiple congenital anomalies, including an atrial septal defect. Despite receiving the best supportive care, she could not be taken off the mechanical ventilator because of severe hypercapnia. We performed LVRS on the right lung via thoracotomy. She was successfully weaned off the mechanical ventilator 1 month after the surgery. She was discharged without severe complications at 3 months after the operation. At present, she is growing well with the help of intermittent home ventilator support. She can now tolerate an oral diet. Our experience shows that LVRS can be considered as a treatment option for pediatric patients with severe emphysematous lung. It is especially helpful for discontinuing prolonged mechanical ventilator care for patients with respiratory failure. Copyright © 2018 by the American Academy of Pediatrics.

Absolute electrical impedance tomography (aEIT) guided ventilation therapy in critical care patients: simulations and future trends.

PubMed

Denaï, Mouloud A; Mahfouf, Mahdi; Mohamad-Samuri, Suzani; Panoutsos, George; Brown, Brian H; Mills, Gary H

2010-05-01

Thoracic electrical impedance tomography (EIT) is a noninvasive, radiation-free monitoring technique whose aim is to reconstruct a cross-sectional image of the internal spatial distribution of conductivity from electrical measurements made by injecting small alternating currents via an electrode array placed on the surface of the thorax. The purpose of this paper is to discuss the fundamentals of EIT and demonstrate the principles of mechanical ventilation, lung recruitment, and EIT imaging on a comprehensive physiological model, which combines a model of respiratory mechanics, a model of the human lung absolute resistivity as a function of air content, and a 2-D finite-element mesh of the thorax to simulate EIT image reconstruction during mechanical ventilation. The overall model gives a good understanding of respiratory physiology and EIT monitoring techniques in mechanically ventilated patients. The model proposed here was able to reproduce consistent images of ventilation distribution in simulated acutely injured and collapsed lung conditions. A new advisory system architecture integrating a previously developed data-driven physiological model for continuous and noninvasive predictions of blood gas parameters with the regional lung function data/information generated from absolute EIT (aEIT) is proposed for monitoring and ventilator therapy management of critical care patients.

Targeted aerosolized delivery of ascorbate in the lungs of chlorine-exposed rats.

PubMed

Bracher, Andreas; Doran, Stephen F; Squadrito, Giuseppe L; Postlethwait, Edward M; Bowen, Larry; Matalon, Sadis

2012-12-01

Chlorine (Cl(2))-induced lung injury is a serious public health threat that may result from industrial and household accidents. Post-Cl(2) administration of aerosolized ascorbate in rodents decreased lung injury and mortality. However, the extent to which aerosolized ascorbate augments depleted ascorbate stores in distal lung compartments has not been assessed. We exposed rats to Cl(2) (300 ppm for 30 min) and returned them to room air. Within 15-30 min postexposure, rats breathed aerosolized ascorbate and desferal or vehicle (mean particle size 3.3 μm) through a nose-only exposure system for 60 min and were euthanized. We measured the concentrations of reduced ascorbate in the bronchoalveolar lavage (BAL), plasma, and lung tissues with high-pressure liquid chromatography, protein plasma concentration in the BAL, and the volume of the epithelia lining fluid (ELF). Cl(2)-exposed rats that breathed aerosolized vehicle had lower values of ascorbate in their BAL, ELF, and lung tissues compared to air-breathing rats. Delivery of aerosolized ascorbate increased reduced ascorbate in BAL, ELF, lung tissues, and plasma of both Cl(2) and air-exposed rats without causing lung injury. Based on mean diameter of aerosolized particles and airway sizes we calculated that approximately 5% and 1% of inhaled ascorbate was deposited in distal lung regions of air and Cl(2)-exposed rats, respectively. Significantly higher ascorbate levels were present in the BAL of Cl(2)-exposed rats when aerosol delivery was initiated 1 h post-Cl(2). Aerosol administration is an effective, safe, and noninvasive method for the delivery of low molecular weight antioxidants to the lungs of Cl(2)-exposed individuals for the purpose of decreasing morbidity and mortality. Delivery is most effective when initiated 1 h postexposure when the effects of Cl(2) on minute ventilation subside.

Parecoxib reduced ventilation induced lung injury in acute respiratory distress syndrome.

PubMed

Meng, Fan-You; Gao, Wei; Ju, Ying-Nan

2017-03-29

Cyclooxygenase-2 (COX-2) contributes to ventilation induced lung injury (VILI) and acute respiratory distress syndrome (ARDS). The objective of present study was to observe the therapeutic effect of parecoxib on VILI in ARDS. In this parallel controlled study performed at Harbin Medical University, China between January 2016 and March 2016, 24 rats were randomly allocated into sham group (S), volume ventilation group/ARDS (VA), parecoxib/volume ventilation group/ARDS (PVA). Rats in the S group only received anesthesia; rats in the VA and PVA group received intravenous injection of endotoxin to induce ARDS, and then received ventilation. Rats in the VA and PVA groups were treated with intravenous injection of saline or parecoxib. The ratio of arterial oxygen pressure to fractional inspired oxygen (PaO 2 /FiO 2 ), the wet to dry weight ratio of lung tissue, inflammatory factors in serum and bronchoalveolar lavage fluid (BALF), and histopathologic analyses of lung tissue were examined. In addition, survival was calculated at 24 h after VILI. Compared to the VA group, in the PVA group, PaO 2 /FiO 2 was significantly increased; lung tissue wet to dry weight ratio; macrophage and neutrophil counts, total protein and neutrophil elastase levels in BALF; tumor necrosis factor-α, interleukin-1β, and prostaglandin E 2 levels in BALF and serum; and myeloperoxidase (MPO) activity, malondialdehyde levels, and Bax and COX-2 protein levels in lung tissue were significantly decreased, while Bcl-2 protein levels were significantly increased. Lung histopathogical changes and apoptosis were reduced by parecpxib in the PVA group. Survival was increased in the PVA group. Parecoxib improves gas exchange and epithelial permeability, decreases edema, reduces local and systemic inflammation, ameliorates lung injury and apoptosis, and increases survival in a rat model of VILI.

An integrated physiology model to study regional lung damage effects and the physiologic response

PubMed Central

2014-01-01

Background This work expands upon a previously developed exercise dynamic physiology model (DPM) with the addition of an anatomic pulmonary system in order to quantify the impact of lung damage on oxygen transport and physical performance decrement. Methods A pulmonary model is derived with an anatomic structure based on morphometric measurements, accounting for heterogeneous ventilation and perfusion observed experimentally. The model is incorporated into an existing exercise physiology model; the combined system is validated using human exercise data. Pulmonary damage from blast, blunt trauma, and chemical injury is quantified in the model based on lung fluid infiltration (edema) which reduces oxygen delivery to the blood. The pulmonary damage component is derived and calibrated based on published animal experiments; scaling laws are used to predict the human response to lung injury in terms of physical performance decrement. Results The augmented dynamic physiology model (DPM) accurately predicted the human response to hypoxia, altitude, and exercise observed experimentally. The pulmonary damage parameters (shunt and diffusing capacity reduction) were fit to experimental animal data obtained in blast, blunt trauma, and chemical damage studies which link lung damage to lung weight change; the model is able to predict the reduced oxygen delivery in damage conditions. The model accurately estimates physical performance reduction with pulmonary damage. Conclusions We have developed a physiologically-based mathematical model to predict performance decrement endpoints in the presence of thoracic damage; simulations can be extended to estimate human performance and escape in extreme situations. PMID:25044032

Collateral Ventilation to Congenital Hyperlucent Lung Lesions Assessed on Xenon-Enhanced Dynamic Dual-Energy CT: an Initial Experience

PubMed Central

Yang, Dong Hyun; Kim, Namkug; Park, Seung Il; Kim, Dong Kwan; Kim, Ellen Ai-Rhan

2011-01-01

Objective We wanted to evaluate the resistance to collateral ventilation in congenital hyperlucent lung lesions and to correlate that with the anatomic findings on xenon-enhanced dynamic dual-energy CT. Materials and Methods Xenon-enhanced dynamic dual-energy CT was successfully and safely performed in eight children (median age: 5.5 years, 4 boys and 4 girls) with congenital hyperlucent lung lesions. Functional assessment of the lung lesions on the xenon map was done, including performing a time-xenon value curve analysis and assessing the amplitude of xenon enhancement (A) value, the rate of xenon enhancement (K) value and the time of arrival value. Based on the A value, the lung lesions were categorized into high or low (A value > 10 Hounsfield unit [HU]) resistance to collateral ventilation. In addition, the morphologic CT findings of the lung lesions, including cyst, mucocele and an accessory or incomplete fissure, were assessed on the weighted-average CT images. The xenon-enhanced CT radiation dose was estimated. Results Five of the eight lung lesions were categorized into the high resistance group and three lesions were categorized into the low resistance group. The A and K values in the normal lung were higher than those in the low resistance group. The time of arrival values were delayed in the low resistance group. Cysts were identified in five lesions, mucocele in four, accessory fissure in three and incomplete fissure in two. Either cyst or an accessory fissure was seen in four of the five lesions showing high resistance to collateral ventilation. The xenon-enhanced CT radiation dose was 2.3 ± 0.6 mSv. Conclusion Xenon-enhanced dynamic dual-energy CT can help visualize and quantitate various degrees of collateral ventilation to congenital hyperlucent lung lesions in addition to assessing the anatomic details of the lung. PMID:21228937

Collateral ventilation to congenital hyperlucent lung lesions assessed on xenon-enhanced dynamic dual-energy CT: an initial experience.

PubMed

Goo, Hyun Woo; Yang, Dong Hyun; Kim, Namkug; Park, Seung Il; Kim, Dong Kwan; Kim, Ellen Ai-Rhan

2011-01-01

We wanted to evaluate the resistance to collateral ventilation in congenital hyperlucent lung lesions and to correlate that with the anatomic findings on xenon-enhanced dynamic dual-energy CT. Xenon-enhanced dynamic dual-energy CT was successfully and safely performed in eight children (median age: 5.5 years, 4 boys and 4 girls) with congenital hyperlucent lung lesions. Functional assessment of the lung lesions on the xenon map was done, including performing a time-xenon value curve analysis and assessing the amplitude of xenon enhancement (A) value, the rate of xenon enhancement (K) value and the time of arrival value. Based on the A value, the lung lesions were categorized into high or low (A value > 10 Hounsfield unit [HU]) resistance to collateral ventilation. In addition, the morphologic CT findings of the lung lesions, including cyst, mucocele and an accessory or incomplete fissure, were assessed on the weighted-average CT images. The xenon-enhanced CT radiation dose was estimated. Five of the eight lung lesions were categorized into the high resistance group and three lesions were categorized into the low resistance group. The A and K values in the normal lung were higher than those in the low resistance group. The time of arrival values were delayed in the low resistance group. Cysts were identified in five lesions, mucocele in four, accessory fissure in three and incomplete fissure in two. Either cyst or an accessory fissure was seen in four of the five lesions showing high resistance to collateral ventilation. The xenon-enhanced CT radiation dose was 2.3 ± 0.6 mSv. Xenon-enhanced dynamic dual-energy CT can help visualize and quantitate various degrees of collateral ventilation to congenital hyperlucent lung lesions in addition to assessing the anatomic details of the lung.

Mechanical ventilation strategies.

PubMed

Keszler, Martin

2017-08-01

Although only a small proportion of full term and late preterm infants require invasive respiratory support, they are not immune from ventilator-associated lung injury. The process of lung damage from mechanical ventilation is multifactorial and cannot be linked to any single variable. Atelectrauma and volutrauma have been identified as the most important and potentially preventable elements of lung injury. Respiratory support strategies for full term and late preterm infants have not been as thoroughly studied as those for preterm infants; consequently, a strong evidence base on which to make recommendations is lacking. The choice of modalities of support and ventilation strategies should be guided by the specific underlying pathophysiologic considerations and the ventilatory approach must be individualized for each patient based on the predominant pathophysiology at the time. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lung protective ventilation strategies in paediatrics-A review.

PubMed

Jauncey-Cooke, Jacqui I; Bogossian, Fiona; East, Chris E

2010-05-01

Ventilator Associated Lung Injury (VALI) is an iatrogenic phenomena that significantly impacts on the morbidity and mortality of critically ill patients. The hazards associated with mechanical ventilation are becoming increasingly understood courtesy of a large body of research. Barotrauma, volutrauma and biotrauma all play a role in VALI. Concomitant to this growth in understanding is the development of strategies to reduce the deleterious impact of mechanical ventilation. The majority of the research is based upon adult populations but with careful extrapolation this review will focus on paediatrics. This review article describes the physiological basis of VALI and discusses the various lung protective strategies that clinicians can employ to minimise its incidence and optimise outcomes for paediatric patients. Copyright 2009 Australian College of Critical Care Nurses Ltd. All rights reserved.

Hypercapnic acidosis attenuates ventilation-induced lung injury by a nuclear factor-κB-dependent mechanism.

PubMed

Contreras, Maya; Ansari, Bilal; Curley, Gerard; Higgins, Brendan D; Hassett, Patrick; O'Toole, Daniel; Laffey, John G

2012-09-01

Hypercapnic acidosis protects against ventilation-induced lung injury. We wished to determine whether the beneficial effects of hypercapnic acidosis in reducing stretch-induced injury were mediated via inhibition of nuclear factor-κB, a key transcriptional regulator in inflammation, injury, and repair. Prospective randomized animal study. University research laboratory. Adult male Sprague-Dawley rats. In separate experimental series, the potential for hypercapnic acidosis to attenuate moderate and severe ventilation-induced lung injury was determined. In each series, following induction of anesthesia and tracheostomy, Sprague-Dawley rats were randomized to (normocapnia; FICO2 0.00) or (hypercapnic acidosis; FICO2 0.05), subjected to high stretch ventilation, and the severity of lung injury and indices of activation of the nuclear factor-κB pathway were assessed. Subsequent in vitro experiments examined the potential for hypercapnic acidosis to reduce pulmonary epithelial inflammation and injury induced by cyclic mechanical stretch. The role of the nuclear factor-κB pathway in hypercapnic acidosis-mediated protection from stretch injury was then determined. Hypercapnic acidosis attenuated moderate and severe ventilation-induced lung injury, as evidenced by improved oxygenation, compliance, and reduced histologic injury compared to normocapnic conditions. Hypercapnic acidosis reduced indices of inflammation such as interleukin-6 and bronchoalveolar lavage neutrophil infiltration. Hypercapnic acidosis reduced the decrement of the nuclear factor-κB inhibitor IκBα and reduced the generation of cytokine-induced neutrophil chemoattractant-1. Hypercapnic acidosis reduced cyclic mechanical stretch-induced nuclear factor-κB activation, reduced interleukin-8 production, and decreased epithelial injury and cell death compared to normocapnia. Hypercapnic acidosis attenuated ventilation-induced lung injury independent of injury severity and decreased mechanical stretch-induced epithelial injury and death, via a nuclear factor-κB-dependent mechanism.

Should lung transplantation be performed for patients on mechanical respiratory support? The US experience.

PubMed

Mason, David P; Thuita, Lucy; Nowicki, Edward R; Murthy, Sudish C; Pettersson, Gösta B; Blackstone, Eugene H

2010-03-01

The study objectives were to (1) compare survival after lung transplantation in patients requiring pretransplant mechanical ventilation or extracorporeal membrane oxygenation with that of patients not requiring mechanical support and (2) identify risk factors for mortality. Data were obtained from the United Network for Organ Sharing for lung transplantation from October 1987 to January 2008. A total of 15,934 primary transplants were performed: 586 in patients on mechanical ventilation and 51 in patients on extracorporeal membrane oxygenation. Differences between nonsupport patients and those on mechanical ventilation or extracorporeal membrane oxygenation support were expressed as 2 propensity scores for use in comparing risk-adjusted survival. Unadjusted survival at 1, 6, 12, and 24 months was 83%, 67%, 62%, and 57% for mechanical ventilation, respectively; 72%, 53%, 50%, and 45% for extracorporeal membrane oxygenation, respectively; and 93%, 85%, 79%, and 70% for unsupported patients, respectively (P < .0001). Recipients on mechanical ventilation were younger, had lower forced vital capacity, and had diagnoses other than emphysema. Recipients on extracorporeal membrane oxygenation were also younger, had higher body mass index, and had diagnoses other than cystic fibrosis/bronchiectasis. Once these variables, transplant year, and propensity for mechanical support were accounted for, survival remained worse after lung transplantation for patients on mechanical ventilation and extracorporeal membrane oxygenation. Although survival after lung transplantation is markedly worse when preoperative mechanical support is necessary, it is not dismal. Thus, additional risk factors for mortality should be considered when selecting patients for lung transplantation to maximize survival. Reduced survival for this high-risk population raises the important issue of balancing maximal individual patient survival against benefit to the maximum number of patients. Copyright 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Effect of re-expansion after short-period lung collapse on pulmonary capillary permeability and pro-inflammatory cytokine gene expression in isolated rabbit lungs.

PubMed

Funakoshi, T; Ishibe, Y; Okazaki, N; Miura, K; Liu, R; Nagai, S; Minami, Y

2004-04-01

Re-expansion pulmonary oedema is a rare complication caused by rapid re-expansion of a chronically collapsed lung. Several cases of pulmonary oedema associated with one-lung ventilation (OLV) have been reported recently. Elevated levels of pro-inflammatory cytokines in pulmonary oedema fluid are suggested to play important roles in its development. Activation of cytokines after re-expansion of collapsed lung during OLV has not been thoroughly investigated. Here we investigated the effects of re-expansion of the collapsed lung on pulmonary oedema formation and pro-inflammatory cytokine expression. Lungs isolated from female white Japanese rabbits were perfused and divided into a basal (BAS) group (n=7, baseline measurement alone), a control (CONT) group (n=9, ventilated without lung collapse for 120 min) and an atelectasis (ATEL) group (n=9, lung collapsed for 55 min followed by re-expansion and ventilation for 65 min). Pulmonary vascular resistance (PVR) and the coefficient of filtration (Kfc) were measured at baseline and 60 and 120 min. At the end of perfusion, bronchoalveolar lavage fluid/plasma protein ratio (B/P), wet/dry lung weight ratio (W/D) and mRNA expressions of tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and myeloperoxidase (MPO) were determined. TNF-alpha and IL-1beta mRNA were significantly up-regulated in lungs of the ATEL group compared with BAS and CONT, though no significant differences were noted in PVR, Kfc, B/P and W/D within and between groups. MPO increased at 120 min in CONT and ATEL groups. Pro-inflammatory cytokines were up-regulated upon re-expansion and ventilation after short-period lung collapse, though no changes were noted in pulmonary capillary permeability.

Neural control of ventilation prevents both over-distension and de-recruitment of experimentally injured lungs.

PubMed

Brander, Lukas; Moerer, Onnen; Hedenstierna, Göran; Beck, Jennifer; Takala, Jukka; Slutsky, Arthur S; Sinderby, Christer

2017-03-01

Endogenous pulmonary reflexes may protect the lungs during mechanical ventilation. We aimed to assess integration of continuous neurally adjusted ventilatory assist (cNAVA), delivering assist in proportion to diaphragm's electrical activity during inspiration and expiration, and Hering-Breuer inflation and deflation reflexes on lung recruitment, distension, and aeration before and after acute lung injury (ALI). In 7 anesthetised rabbits with bilateral pneumothoraces, we identified adequate cNAVA level (cNAVA AL ) at the plateau in peak ventilator pressure during titration procedures before (healthy lungs with endotracheal tube, [HL ETT ]) and after ALI (endotracheal tube [ALI ETT ] and during non-invasive ventilation [ALI NIV ]). Following titration, cNAVA AL was maintained for 5min. In 2 rabbits, procedures were repeated after vagotomy (ALI ETT+VAG ). In 3 rabbits delivery of assist was temporarily modulated to provide assist on inspiration only. Computed tomography was performed before intubation, before ALI, during cNAVA titration, and after maintenance at cNAVA AL . During ALI ETT and ALI NIV , normally aerated lung-regions doubled and poorly aerated lung-regions decreased to less than a third (p<0.05) compared to HL ETT ; no over-distension was observed. Tidal volumes were<5ml/kg throughout. Removing assist during expiration resulted in lung de-recruitment during ALI ETT , but not during ALI NIV . During ALI ETT+VAG the expiratory portion of EAdi disappeared, resulting in cyclic lung collapse and recruitment. When using cNAVA in ALI, vagally mediated reflexes regulated lung recruitment preventing both lung over-distension and atelectasis. During non-invasive cNAVA the upper airway muscles play a role in preventing atelectasis. Future studies should be performed to compare these findings with conventional lung-protective approaches. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of 133 xenon ventilation equilibrium scan (XV) and 99m technetium transmission (TT) scan for use in regional lung analysis by 2D gamma scintigraphy in healthy and cystic fibrosis lungs.

PubMed

Zeman, Kirby L; Wu, Jihong; Donaldson, Scott H; Bennett, William D

2013-04-01

Quantification of particle deposition in the lung by gamma scintigraphy requires a reference image for location of regions of interest (ROIs) and normalization to lung thickness. In various laboratories, the reference image is made by a transmission scan ((57)Co or (99m)Tc) or gas ventilation scan ((133)Xe or (81)Kr). There has not been a direct comparison of measures from the two methods. We compared (99m)Tc transmission scans to (133)Xe equilibrium ventilation scans as reference images for 38 healthy subjects and 14 cystic fibrosis (CF) patients for their effects on measures of regional particle deposition: the central-to-peripheral ratio of lung counts (C/P); and ROI area versus forced vital capacity. Whole right lung ROI was based on either an isocontour threshold of three times the soft tissue transmission (TT) or a threshold of 20% of peak xenon ventilation counts (XV). We used a central ROI drawn to 50% of height and of width of the whole right lung ROI and placed along the left lung margin and centered vertically. In general, the correlation of normalized C/P (nC/P) between the two methods was strong. However, the value of nC/P was significantly smaller for the XV method than the TT method. Regression equations for the relationship of nC/P between the two methods were, for healthy subjects, y=0.75x+0.61, R(2)=0.64 using rectangular ROIs and y=0.76x+0.45, R(2)=0.66 using isocontour ROIs; and for CF patients, y=0.94x+0.46, R(2)=0.43 and y=0.85x+0.42, R(2)=0.41, respectively. (1) A transmission scan with an isocontour outline in combination with a rectangular central region to define the lung borders may be more useful than a ventilation scan. (2) Close correlation of nC/Ps measured by transmission or gas ventilation should allow confident comparison of values determined by the two methods.

Adjusting tidal volume to stress index in an open lung condition optimizes ventilation and prevents overdistension in an experimental model of lung injury and reduced chest wall compliance.

PubMed

Ferrando, Carlos; Suárez-Sipmann, Fernando; Gutierrez, Andrea; Tusman, Gerardo; Carbonell, Jose; García, Marisa; Piqueras, Laura; Compañ, Desamparados; Flores, Susanie; Soro, Marina; Llombart, Alicia; Belda, Francisco Javier

2015-01-13

The stress index (SI), a parameter derived from the shape of the pressure-time curve, can identify injurious mechanical ventilation. We tested the hypothesis that adjusting tidal volume (VT) to a non-injurious SI in an open lung condition avoids hypoventilation while preventing overdistension in an experimental model of combined lung injury and low chest-wall compliance (Ccw). Lung injury was induced by repeated lung lavages using warm saline solution, and Ccw was reduced by controlled intra-abdominal air-insufflation in 22 anesthetized, paralyzed and mechanically ventilated pigs. After injury animals were recruited and submitted to a positive end-expiratory pressure (PEEP) titration trial to find the PEEP level resulting in maximum compliance. During a subsequent four hours of mechanical ventilation, VT was adjusted to keep a plateau pressure (Pplat) of 30 cmH2O (Pplat-group, n = 11) or to a SI between 0.95 and 1.05 (SI-group, n = 11). Respiratory rate was adjusted to maintain a 'normal' PaCO2 (35 to 65 mmHg). SI, lung mechanics, arterial-blood gases haemodynamics pro-inflammatory cytokines and histopathology were analyzed. In addition Computed Tomography (CT) data were acquired at end expiration and end inspiration in six animals. PaCO2 was significantly higher in the Pplat-group (82 versus 53 mmHg, P = 0.01), with a resulting lower pH (7.19 versus 7.34, P = 0.01). We observed significant differences in VT (7.3 versus 5.4 mlKg(-1), P = 0.002) and Pplat values (30 versus 35 cmH2O, P = 0.001) between the Pplat-group and SI-group respectively. SI (1.03 versus 0.99, P = 0.42) and end-inspiratory transpulmonary pressure (PTP) (17 versus 18 cmH2O, P = 0.42) were similar in the Pplat- and SI-groups respectively, without differences in overinflated lung areas at end- inspiration in both groups. Cytokines and histopathology showed no differences. Setting tidal volume to a non-injurious stress index in an open lung condition improves alveolar ventilation and prevents overdistension without increasing lung injury. This is in comparison with limited Pplat protective ventilation in a model of lung injury with low chest-wall compliance.

Open Lung Approach for the Acute Respiratory Distress Syndrome: A Pilot, Randomized Controlled Trial.

PubMed

Kacmarek, Robert M; Villar, Jesús; Sulemanji, Demet; Montiel, Raquel; Ferrando, Carlos; Blanco, Jesús; Koh, Younsuck; Soler, Juan Alfonso; Martínez, Domingo; Hernández, Marianela; Tucci, Mauro; Borges, Joao Batista; Lubillo, Santiago; Santos, Arnoldo; Araujo, Juan B; Amato, Marcelo B P; Suárez-Sipmann, Fernando

2016-01-01

The open lung approach is a mechanical ventilation strategy involving lung recruitment and a decremental positive end-expiratory pressure trial. We compared the Acute Respiratory Distress Syndrome network protocol using low levels of positive end-expiratory pressure with open lung approach resulting in moderate to high levels of positive end-expiratory pressure for the management of established moderate/severe acute respiratory distress syndrome. A prospective, multicenter, pilot, randomized controlled trial. A network of 20 multidisciplinary ICUs. Patients meeting the American-European Consensus Conference definition for acute respiratory distress syndrome were considered for the study. At 12-36 hours after acute respiratory distress syndrome onset, patients were assessed under standardized ventilator settings (FIO2≥0.5, positive end-expiratory pressure ≥10 cm H2O). If Pao2/FIO2 ratio remained less than or equal to 200 mm Hg, patients were randomized to open lung approach or Acute Respiratory Distress Syndrome network protocol. All patients were ventilated with a tidal volume of 4 to 8 ml/kg predicted body weight. From 1,874 screened patients with acute respiratory distress syndrome, 200 were randomized: 99 to open lung approach and 101 to Acute Respiratory Distress Syndrome network protocol. Main outcome measures were 60-day and ICU mortalities, and ventilator-free days. Mortality at day-60 (29% open lung approach vs. 33% Acute Respiratory Distress Syndrome Network protocol, p = 0.18, log rank test), ICU mortality (25% open lung approach vs. 30% Acute Respiratory Distress Syndrome network protocol, p = 0.53 Fisher's exact test), and ventilator-free days (8 [0-20] open lung approach vs. 7 [0-20] d Acute Respiratory Distress Syndrome network protocol, p = 0.53 Wilcoxon rank test) were not significantly different. Airway driving pressure (plateau pressure - positive end-expiratory pressure) and PaO2/FIO2 improved significantly at 24, 48 and 72 hours in patients in open lung approach compared with patients in Acute Respiratory Distress Syndrome network protocol. Barotrauma rate was similar in both groups. In patients with established acute respiratory distress syndrome, open lung approach improved oxygenation and driving pressure, without detrimental effects on mortality, ventilator-free days, or barotrauma. This pilot study supports the need for a large, multicenter trial using recruitment maneuvers and a decremental positive end-expiratory pressure trial in persistent acute respiratory distress syndrome.

Physiologic effects of alveolar recruitment and inspiratory pauses during moderately-high-frequency ventilation delivered by a conventional ventilator in a severe lung injury model

PubMed Central

Costa, Eduardo Leite Vieira; Azevedo, Luciano Cesar Pontes; Gomes, Susimeire; Amato, Marcelo Britto Passos; Park, Marcelo

2017-01-01

Background and aims To investigate whether performing alveolar recruitment or adding inspiratory pauses could promote physiologic benefits (VT) during moderately-high-frequency positive pressure ventilation (MHFPPV) delivered by a conventional ventilator in a porcine model of severe acute respiratory distress syndrome (ARDS). Methods Prospective experimental laboratory study with eight pigs. Induction of acute lung injury with sequential pulmonary lavages and injurious ventilation was initially performed. Then, animals were ventilated on a conventional mechanical ventilator with a respiratory rate (RR) = 60 breaths/minute and PEEP titrated according to ARDS Network table. The first two steps consisted of a randomized order of inspiratory pauses of 10 and 30% of inspiratory time. In final step, we removed the inspiratory pause and titrated PEEP, after lung recruitment, with the aid of electrical impedance tomography. At each step, PaCO2 was allowed to stabilize between 57–63 mmHg for 30 minutes. Results The step with RR of 60 after lung recruitment had the highest PEEP when compared with all other steps (17 [16,19] vs 14 [10, 17]cmH2O), but had lower driving pressures (13 [13,11] vs 16 [14, 17]cmH2O), higher P/F ratios (212 [191,243] vs 141 [105, 184] mmHg), lower shunt (23 [20, 23] vs 32 [27, 49]%), lower dead space ventilation (10 [0, 15] vs 30 [20, 37]%), and a more homogeneous alveolar ventilation distribution. There were no detrimental effects in terms of lung mechanics, hemodynamics, or gas exchange. Neither the addition of inspiratory pauses or the alveolar recruitment maneuver followed by decremental PEEP titration resulted in further reductions in VT. Conclusions During MHFPPV set with RR of 60 bpm delivered by a conventional ventilator in severe ARDS swine model, neither the inspiratory pauses or PEEP titration after recruitment maneuver allowed reduction of VT significantly, however the last strategy decreased driving pressures and improved both shunt and dead space. PMID:28961282

Exogenous surfactant preserves lung function and reduces alveolar Evans blue dye influx in a rat model of ventilation-induced lung injury.

PubMed

Verbrugge, S J; Vazquez de Anda, G; Gommers, D; Neggers, S J; Sorm, V; Böhm, S H; Lachmann, B

1998-08-01

Changes in pulmonary edema infiltration and surfactant after intermittent positive pressure ventilation with high peak inspiratory lung volumes have been well described. To further elucidate the role of surfactant changes, the authors tested the effect of different doses of exogenous surfactant preceding high peak inspiratory lung volumes on lung function and lung permeability. Five groups of Sprague-Dawley rats (n = 6 per group) were subjected to 20 min of high peak inspiratory lung volumes. Before high peak inspiratory lung volumes, four of these groups received intratracheal administration of saline or 50, 100, or 200 mg/kg body weight surfactant; one group received no intratracheal administration. Gas exchange was measured during mechanical ventilation. A sixth group served as nontreated, nonventilated controls. After death, all lungs were excised, and static pressure-volume curves and total lung volume at a transpulmonary pressure of 5 cm H2O were recorded. The Gruenwald index and the steepest part of the compliance curve (Cmax) were calculated. A bronchoalveolar lavage was performed; surfactant small and large aggregate total phosphorus and minimal surface tension were measured. In a second experiment in five groups of rats (n = 6 per group), lung permeability for Evans blue dye was measured. Before 20 min of high peak inspiratory lung volumes, three groups received intratracheal administration of 100, 200, or 400 mg/ kg body weight surfactant; one group received no intratracheal administration. A fifth group served as nontreated, nonventilated controls. Exogenous surfactant at a dose of 200 mg/kg preserved total lung volume at a pressure of 5 cm H2O, maximum compliance, the Gruenwald Index, and oxygenation after 20 min of mechanical ventilation. The most active surfactant was recovered in the group that received 200 mg/kg surfactant, and this dose reduced minimal surface tension of bronchoalveolar lavage to control values. Alveolar influx of Evans blue dye was reduced in the groups that received 200 and 400 mg/kg exogenous surfactant. Exogenous surfactant preceding high peak inspiratory lung volumes prevents impairment of oxygenation, lung mechanics, and minimal surface tension of bronchoalveolar lavage fluid and reduces alveolar influx of Evans blue dye. These data indicate that surfactant has a beneficial effect on ventilation-induced lung injury.

The Effects of Prone Position Ventilation on Experimental Mild Acute Lung Injury Induced by Intraperitoneal Lipopolysaccharide Injection in Rats.

PubMed

Bianchi, Aydra Mendes Almeida; Reboredo, Maycon Moura; Lucinda, Leda Marília Fonseca; Reis, Fernando Fonseca; Silva, Manfrinni Vinícius Alves; Rabelo, Maria Aparecida Esteves; Holanda, Marcelo Alcantara; Oliveira, Júlio César Abreu; Lorente, José Ángel; Pinheiro, Bruno do Valle

2016-04-01

The benefits of prone position ventilation are well demonstrated in the severe forms of acute respiratory distress syndrome, but not in the milder forms. We investigated the effects of prone position on arterial blood gases, lung inflammation, and histology in an experimental mild acute lung injury (ALI) model. ALI was induced in Wistar rats by intraperitoneal Escherichia coli lipopolysaccharide (LPS, 5 mg/kg). After 24 h, the animals with PaO2/FIO2 between 200 and 300 mmHg were randomized into 2 groups: prone position (n = 6) and supine position (n = 6). Both groups were compared with a control group (n = 5) that was ventilated in the supine position. All of the groups were ventilated for 1 h with volume-controlled ventilation mode (tidal volume = 6 ml/kg, respiratory rate = 80 breaths/min, positive end-expiratory pressure = 5 cmH2O, inspired oxygen fraction = 1) RESULTS: Significantly higher lung injury scores were observed in the LPS-supine group compared to the LPS-prone and control groups (0.32 ± 0.03; 0.17 ± 0.03 and 0.13 ± 0.04, respectively) (p < 0.001), mainly due to a higher neutrophil infiltration level in the interstitial space and more proteinaceous debris that filled the airspaces. Similar differences were observed when the gravity-dependent lung regions and non-dependent lung regions were analyzed separately (p < 0.05). The BAL neutrophil content was also higher in the LPS-supine group compared to the LPS-prone and control groups (p < 0.05). There were no significant differences in the wet/dry ratio and gas exchange levels. In this experimental extrapulmonary mild ALI model, prone position ventilation for 1 h, when compared with supine position ventilation, was associated with lower lung inflammation and injury.

Prone positioning ventilation for treatment of acute lung injury and acute respiratory distress syndrome.

PubMed

Lan, Mei-juan; He, Xiao-di

2009-08-01

Patients who are diagnosed with acute lung injury/acute respiratory distress syndrome (ALI/ARDS) usually have ventilation-perfusion mismatch, severe decrease in lung capacity, and gas exchange abnormalities. Health care workers have implemented various strategies in an attempt to compensate for these pathological alterations. By rotating patients with ALI/ARDS between the supine and prone position, it is possible to achieve a significant improvement in PaO2/FiO2, decrease shunting and therefore improve oxygenation without use of expensive, invasive and experimental procedures. Prone positioning is a safe and effective way to improve ventilation when conventional strategies fail to initiate a patient response. Because a specific cure for ARDS is not available, the goal is to support the patients with therapies that cause the least amount of injury while the lungs have an opportunity to heal. Based on current data, a trial of prone positioning ventilation should be offered to the patients who have ALI/ARDS in the early course of the disease. Published studies exhibit substantial heterogeneity in clinical results, suggesting that an adequately sized study optimizing the duration of proning ventilation strategy is warranted to enable definitive conclusions to be drawn.

Hyperpolarized (3)He magnetic resonance imaging: comparison with four-dimensional x-ray computed tomography imaging in lung cancer.

PubMed

Mathew, Lindsay; Wheatley, Andrew; Castillo, Richard; Castillo, Edward; Rodrigues, George; Guerrero, Thomas; Parraga, Grace

2012-12-01

Pulmonary functional imaging using four-dimensional x-ray computed tomographic (4DCT) imaging and hyperpolarized (3)He magnetic resonance imaging (MRI) provides regional lung function estimates in patients with lung cancer in whom pulmonary function measurements are typically dominated by tumor burden. The aim of this study was to evaluate the quantitative spatial relationship between 4DCT and hyperpolarized (3)He MRI ventilation maps. Eleven patients with lung cancer provided written informed consent to 4DCT imaging and MRI performed within 11 ± 14 days. Hyperpolarized (3)He MRI was acquired in breath-hold after inhalation from functional residual capacity of 1 L hyperpolarized (3)He, whereas 4DCT imaging was acquired over a single tidal breath of room air. For hyperpolarized (3)He MRI, the percentage ventilated volume was generated using semiautomated segmentation; for 4DCT imaging, pulmonary function maps were generated using the correspondence between identical tissue elements at inspiratory and expiratory phases to generate percentage ventilated volume. After accounting for differences in image acquisition lung volumes ((3)He MRI: 1.9 ± 0.5 L ipsilateral, 2.3 ± 0.7 L contralateral; 4DCT imaging: 1.2 ± 0.3 L ipsilateral, 1.3 ± 0.4 L contralateral), there was no significant difference in percentage ventilated volume between hyperpolarized (3)He MRI (72 ± 11% ipsilateral, 79 ± 12% contralateral) and 4DCT imaging (74 ± 3% ipsilateral, 75 ± 4% contralateral). Spatial correspondence between 4DCT and (3)He MRI ventilation was evaluated using the Dice similarity coefficient index (ipsilateral, 86 ± 12%; contralateral, 88 ± 12%). Despite rather large differences in image acquisition breathing maneuvers, good spatial and significant quantitative agreement was observed for ventilation maps on hyperpolarized (3)He MRI and 4DCT imaging, suggesting that pulmonary regions with good lung function are similar between modalities in this small group of patients with lung cancer. Copyright © 2012 AUR. Published by Elsevier Inc. All rights reserved.

Randomised comparison of two neonatal resuscitation bags in manikin ventilation.

PubMed

Thallinger, Monica; Ersdal, Hege Langli; Ombay, Crescent; Eilevstjønn, Joar; Størdal, Ketil

2016-07-01

To compare ventilation properties and user preference of a new upright neonatal resuscitator developed for easier cleaning, reduced complexity, and possibly improved ventilation properties, with the standard Laerdal neonatal resuscitator. Eighty-seven Tanzanian and Norwegian nursing and medical students without prior knowledge of newborn resuscitation were briefly trained in bag-mask ventilation. The two resuscitators were used in random order on a manikin connected to a test lung with normal or low lung compliance. Data were collected with the Laerdal Newborn Resuscitation Monitor. The students graded mask seal and ease of air entry on a four-point scale ranging from 1 ('difficult') to 4 ('easy') and stated which device they preferred. (Equipment from Laerdal Global Health and Laerdal Medical). For upright versus standard resuscitator and normal lung compliance, mean expiratory lung volume was 15.5 mL vs 13.9 mL (p=0.001), mean mask leakage 48% vs 58% (p<0.001), and mean airway pressure 20 cm H2O vs 19 cm H2O (p=0.003), respectively. For low lung compliance, mean expiratory lung volume was 8.6 mL vs 8.1 mL (p=0.045), mean mask leakage 53% vs 62% (p<0.001), and mean airway pressure 21 cm H2O vs 20 cm H2O (p=0.004) for upright versus standard. The upright resuscitator was preferred by 82% and 68% of students during ventilation with normal and low lung compliance, respectively (p=0.001). Expiratory volumes were higher, mask leakage lower, and mean airway pressure slightly higher with upright versus standard resuscitator when ventilating a manikin. The majority of students preferred the upright resuscitator. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

The lung in space.

PubMed

Prisk, G Kim

2005-09-01

The lung is exquisitely sensitive to gravity, which induces gradients in ventilation, blood flow, and gas exchange. Studies of lungs in microgravity provide a means of elucidating the effects of gravity. They suggest a mechanism by which gravity serves to match ventilation to perfusion, making for a more efficient lung than anticipated. Despite predictions, lungs do not become edematous, and there is no disruption to, gas exchange in microgravity. Sleep disturbances in microgravity are not a result of respiratory-related events; obstructive sleep apnea is caused principally by the gravitational effects on the upper airways. In microgravity, lungs may be at greater risk to the effects of inhaled aerosols.

The lung in space

NASA Technical Reports Server (NTRS)

Prisk, G. Kim

2005-01-01

The lung is exquisitely sensitive to gravity, which induces gradients in ventilation, blood flow, and gas exchange. Studies of lungs in microgravity provide a means of elucidating the effects of gravity. They suggest a mechanism by which gravity serves to match ventilation to perfusion, making for a more efficient lung than anticipated. Despite predictions, lungs do not become edematous, and there is no disruption to, gas exchange in microgravity. Sleep disturbances in microgravity are not a result of respiratory-related events; obstructive sleep apnea is caused principally by the gravitational effects on the upper airways. In microgravity, lungs may be at greater risk to the effects of inhaled aerosols.

A poroelastic model coupled to a fluid network with applications in lung modelling.

PubMed

Berger, Lorenz; Bordas, Rafel; Burrowes, Kelly; Grau, Vicente; Tavener, Simon; Kay, David

2016-01-01

We develop a lung ventilation model based on a continuum poroelastic representation of lung parenchyma that is strongly coupled to a pipe network representation of the airway tree. The continuous system of equations is discretized using a low-order stabilised finite element method. The framework is applied to a realistic lung anatomical model derived from computed tomography data and an artificially generated airway tree to model the conducting airway region. Numerical simulations produce physiologically realistic solutions and demonstrate the effect of airway constriction and reduced tissue elasticity on ventilation, tissue stress and alveolar pressure distribution. The key advantage of the model is the ability to provide insight into the mutual dependence between ventilation and deformation. This is essential when studying lung diseases, such as chronic obstructive pulmonary disease and pulmonary fibrosis. Thus the model can be used to form a better understanding of integrated lung mechanics in both the healthy and diseased states. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Protective ventilation in experimental acute respiratory distress syndrome after ventilator-induced lung injury: a randomized controlled trial.

PubMed

Uttman, L; Bitzén, U; De Robertis, E; Enoksson, J; Johansson, L; Jonson, B

2012-10-01

Low tidal volume (V(T)), PEEP, and low plateau pressure (P(PLAT)) are lung protective during acute respiratory distress syndrome (ARDS). This study tested the hypothesis that the aspiration of dead space (ASPIDS) together with computer simulation can help maintain gas exchange at these settings, thus promoting protection of the lungs. ARDS was induced in pigs using surfactant perturbation plus an injurious ventilation strategy. One group then underwent 24 h protective ventilation, while control groups were ventilated using a conventional ventilation strategy at either high or low pressure. Pressure-volume curves (P(el)/V), blood gases, and haemodynamics were studied at 0, 4, 8, 16, and 24 h after the induction of ARDS and lung histology was evaluated. The P(el)/V curves showed improvements in the protective strategy group and deterioration in both control groups. In the protective group, when respiratory rate (RR) was ≈ 60 bpm, better oxygenation and reduced shunt were found. Histological damage was significantly more severe in the high-pressure group. There were no differences in venous oxygen saturation and pulmonary vascular resistance between the groups. The protective ventilation strategy of adequate pH or PaCO2 with minimal V(T), and high/safe P(PLAT) resulting in high PEEP was based on the avoidance of known lung-damaging phenomena. The approach is based upon the optimization of V(T), RR, PEEP, I/E, and dead space. This study does not lend itself to conclusions about the independent role of each of these features. However, dead space reduction is fundamental for achieving minimal V(T) at high RR. Classical physiology is applicable at high RR. Computer simulation optimizes ventilation and limiting of dead space using ASPIDS. Inspiratory P(el)/V curves recorded from PEEP or, even better, expiratory P(el)/V curves allow monitoring in ARDS.

Simple, Inexpensive Model Spirometer for Understanding Ventilation Volumes

ERIC Educational Resources Information Center

Giuliodori, Mauricio J.; DiCarlo, Stephen E.

2004-01-01

Spirometers are useful for enhancing students' understanding of normal lung volumes, capacities, and flow rates. Spirometers are also excellent for understanding how lung diseases alter ventilation volumes. However, spirometers are expensive, complex, and not appropriate for programs with limited space and budgets. Therefore, we developed a…

Improved OCT imaging of lung tissue using a prototype for total liquid ventilation

NASA Astrophysics Data System (ADS)

Schnabel, Christian; Meissner, Sven; Koch, Edmund

2011-06-01

Optical coherence tomography (OCT) is used for imaging subpleural alveoli in animal models to gain information about dynamic and morphological changes of lung tissue during mechanical ventilation. The quality of OCT images can be increased if the refraction index inside the alveoli is matched to the one of tissue via liquid-filling. Thereby, scattering loss can be decreased and higher penetration depth and tissue contrast can be achieved. Until now, images of liquid-filled lungs were acquired in isolated and fixated lungs only, so that an in vivo measurement situation is not present. To use the advantages of liquid-filling for in vivo imaging of small rodent lungs, it was necessary to develop a liquid ventilator. Perfluorodecalin, a perfluorocarbon, was selected as breathing fluid because of its refraction index being similar to the one of water and the high transport capacity for carbon dioxide and oxygen. The setup is characterized by two independent syringe pumps to insert and withdraw the fluid into and from the lung and a custom-made control program for volume- or pressure-controlled ventilation modes. The presented results demonstrate the liquid-filling verified by optical coherence tomography and intravital microscopy (IVM) and the advantages of liquid-filling to OCT imaging of subpleural alveoli.

Lung transplantation in the spotlight: Reasons for high-cost procedures.

PubMed

Vogl, Matthias; Warnecke, Gregor; Haverich, Axel; Gottlieb, Jens; Welte, Tobias; Hatz, Rudolf; Hunger, Matthias; Leidl, Reiner; Lingner, Heidrun; Behr, Juergen; Winter, Hauke; Schramm, Rene; Zwissler, Bernhard; Hagl, Christian; Strobl, Nicole; Jaeger, Cornelius; Preissler, Gerhard

2016-10-01

Hospital treatment costs of lung transplantation are insufficiently analyzed. Accordingly, it remains unknown, whether current Diagnosis Related Groups, merely accounting for 3 ventilation time intervals and length of hospital stay, reproduce costs properly, even when an increasing number of complex recipients are treated. Therefore, in this cost determination study, actual costs were calculated and cost drivers identified. A standardized microcosting approach allowed for individual cost calculations in 780 lung transplant patients taken care of at Hannover Medical School and University of Munich from 2009 to 2013. A generalized linear model facilitated the determination of characteristics predictive for inpatient costs. Lung transplantation costs varied substantially by major diagnosis, with a mean of €85,946 (median €52,938 ± 3,081). Length of stay and ventilation time properly reproduced costs in many cases. However, complications requiring prolonged ventilation or reinterventions were identified as additional significant cost drivers, responsible for high costs. Diagnosis Related Groups properly reproduce actual lung transplantation costs in straightforward cases, but costs in complex cases may remain underestimated. Improved grouping should consider major diagnosis, a higher gradation of ventilation time, and the number of reinterventions to allow for more reasonable reimbursement. Copyright © 2016 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

Lung volume, breathing pattern and ventilation inhomogeneity in preterm and term infants.

PubMed

Latzin, Philipp; Roth, Stefan; Thamrin, Cindy; Hutten, Gerard J; Pramana, Isabelle; Kuehni, Claudia E; Casaulta, Carmen; Nelle, Matthias; Riedel, Thomas; Frey, Urs

2009-01-01

Morphological changes in preterm infants with bronchopulmonary dysplasia (BPD) have functional consequences on lung volume, ventilation inhomogeneity and respiratory mechanics. Although some studies have shown lower lung volumes and increased ventilation inhomogeneity in BPD infants, conflicting results exist possibly due to differences in sedation and measurement techniques. We studied 127 infants with BPD, 58 preterm infants without BPD and 239 healthy term-born infants, at a matched post-conceptional age of 44 weeks during quiet natural sleep according to ATS/ERS standards. Lung function parameters measured were functional residual capacity (FRC) and ventilation inhomogeneity by multiple breath washout as well as tidal breathing parameters. Preterm infants with BPD had only marginally lower FRC (21.4 mL/kg) than preterm infants without BPD (23.4 mL/kg) and term-born infants (22.6 mL/kg), though there was no trend with disease severity. They also showed higher respiratory rates and lower ratios of time to peak expiratory flow and expiratory time (t(PTEF)/t(E)) than healthy preterm and term controls. These changes were related to disease severity. No differences were found for ventilation inhomogeneity. Our results suggest that preterm infants with BPD have a high capacity to maintain functional lung volume during natural sleep. The alterations in breathing pattern with disease severity may reflect presence of adaptive mechanisms to cope with the disease process.

Determination of airway humidification in high-frequency oscillatory ventilation using an artificial neonatal lung model. Comparison of a heated humidifier and a heat and moisture exchanger.

PubMed

Schiffmann, H; Singer, S; Singer, D; von Richthofen, E; Rathgeber, J; Züchner, K

1999-09-01

Thus far only few data are available on airway humidification during high-frequency oscillatory ventilation (HFOV). Therefore, we studied the performance and efficiency of a heated humidifier (HH) and a heat and moisture exchanger (HME) in HFOV using an artificial lung model. Experiments were performed with a pediatric high-frequency oscillatory ventilator. The artificial lung contained a sponge saturated with water to simulate evaporation and was placed in an incubator heated to 37 degrees C to prevent condensation. The airway humidity was measured using a capacitive humidity sensor. The water loss of the lung model was determined gravimetrically. The water loss of the lung model varied between 2.14 and 3.1 g/h during active humidification; it was 2.85 g/h with passive humidification and 7.56 g/h without humidification. The humidity at the tube connector varied between 34. 2 and 42.5 mg/l, depending on the temperature of the HH and the ventilator setting during active humidification, and between 37 and 39.9 mg/l with passive humidification. In general, HH and HME are suitable devices for airway humidification in HFOV. The performance of the ventilator was not significantly influenced by the mode of humidification. However, the adequacy of humidification and safety of the HME remains to be demonstrated in clinical practice.

The efficacy of fluorocarbon, surfactant, and their combination for improving acute lung injury induced by intratracheal acidified infant formula.

PubMed

Nishina, Kahoru; Mikawa, Katsuya; Takao, Yumiko; Obara, Hidefumi

2005-04-01

We conducted the current study to compare the efficacy of partial liquid ventilation (PLV), pulmonary surfactant (PSF), and their combination in ameliorating the acidified infant-formula-induced acute lung injury (ALI). In the Part I study, 42 rabbits receiving volume-controlled ventilation with positive end-expiratory pressure 10 cm H(2)O were randomly divided into 6 groups (groups noninjuryI, gas ventilation [GVi], PLVi, PSFi, PLVi-->PSFi, and PSFi-->PLVi). ALI was induced by intratracheal acidified infant formula (2 mL/kg, pH 1.8). Group GVi received neither PLV nor PSF therapy. Groups PLV and PSF received intratracheal fluorocarbon 15 mL/kg or surfactant 100 mg/kg, respectively, 30 min after acidified infant formula. Groups PLVi-->PSFi and PSFi-->PLVi received both treatments at 30-min intervals. In Part II, 42 rabbits (in 6 groups) undergoing pressure-controlled ventilation received the same drug therapies as in Part I. The lungs were excised to assess biochemical and histological damage 150 min after induction of ALI. In Parts I and II, PSF, fluorocarbon, and their combination attenuated lung leukosequestration and edema and superoxide production of neutrophils, consequently improving oxygenation, lung mechanics, and pathological changes. Independent of ventilation mode, PSF followed by fluorocarbon provided the most beneficial effects and fluorocarbon followed by PSF produced the least efficacy.

Postural lung recruitment assessed by lung ultrasound in mechanically ventilated children.

PubMed

Tusman, Gerardo; Acosta, Cecilia M; Böhm, Stephan H; Waldmann, Andreas D; Ferrando, Carlos; Marquez, Manuel Perez; Sipmann, Fernando Suarez

2017-10-13

Atelectasis is a common finding in mechanically ventilated children with healthy lungs. This lung collapse cannot be overcome using standard levels of positive end-expiratory pressure (PEEP) and thus for only individualized lung recruitment maneuvers lead to satisfactory therapeutic results. In this short communication, we demonstrate by lung ultrasound images (LUS) the effect of a postural recruitment maneuver (P-RM, i.e., a ventilatory strategy aimed at reaerating atelectasis by changing body position under constant ventilation). Data was collected in the operating room of the Hospital Privado de Comunidad, Mar del Plata, Argentina. Three anesthetized children undergoing mechanical ventilation at constant settings were sequentially subjected to the following two maneuvers: (1) PEEP trial in the supine position PEEP was increased to 10 cmH 2 O for 3 min and then decreased to back to baseline. (2) P-RM patient position was changed from supine to the left and then to the right lateral position for 90 s each before returning to supine. The total P-RM procedure took approximately 3 min. LUS in the supine position showed similar atelectasis before and after the PEEP trial. Contrarily, atelectasis disappeared in the non-dependent lung when patients were placed in the lateral positions. Both lungs remained atelectasis free even after returning to the supine position. We provide LUS images that illustrate the concept and effects of postural recruitment in children. This maneuver has the advantage of achieving recruitment effects without the need to elevate airways pressures.

Imaging Lung Function in Mice Using SPECT/CT and Per-Voxel Analysis

PubMed Central

Jobse, Brian N.; Rhem, Rod G.; McCurry, Cory A. J. R.; Wang, Iris Q.; Labiris, N. Renée

2012-01-01

Chronic lung disease is a major worldwide health concern but better tools are required to understand the underlying pathologies. Ventilation/perfusion (V/Q) single photon emission computed tomography (SPECT) with per-voxel analysis allows for non-invasive measurement of regional lung function. A clinically adapted V/Q methodology was used in healthy mice to investigate V/Q relationships. Twelve week-old mice were imaged to describe normal lung function while 36 week-old mice were imaged to determine how age affects V/Q. Mice were ventilated with Technegas™ and injected with 99mTc-macroaggregated albumin to trace ventilation and perfusion, respectively. For both processes, SPECT and CT images were acquired, co-registered, and quantitatively analyzed. On a per-voxel basis, ventilation and perfusion were moderately correlated (R = 0.58±0.03) in 12 week old animals and a mean log(V/Q) ratio of −0.07±0.01 and standard deviation of 0.36±0.02 were found, defining the extent of V/Q matching. In contrast, 36 week old animals had significantly increased levels of V/Q mismatching throughout the periphery of the lung. Measures of V/Q were consistent across healthy animals and differences were observed with age demonstrating the capability of this technique in quantifying lung function. Per-voxel analysis and the ability to non-invasively assess lung function will aid in the investigation of chronic lung disease models and drug efficacy studies. PMID:22870297

Work of breathing using different interfaces in spontaneous positive pressure ventilation: helmet, face-mask, and endotracheal tube.

PubMed

Oda, Shinya; Otaki, Kei; Yashima, Nozomi; Kurota, Misato; Matsushita, Sachiko; Kumasaka, Airi; Kurihara, Hutaba; Kawamae, Kaneyuki

2016-08-01

Noninvasive positive pressure ventilation (NPPV) using a helmet is expected to cause inspiratory trigger delay due to the large collapsible and compliant chamber. We compared the work of breathing (WOB) of NPPV using a helmet or a full face-mask with that of invasive ventilation by tracheal intubation. We used a lung model capable of simulating spontaneous breathing (LUNGOO; Air Water Inc., Japan). LUNGOO was set at compliance (C) = 50 mL/cmH2O and resistance (R) = 5 cmH2O/L/s for normal lung simulation, C = 20 mL/cmH2O and R = 5 cmH2O/L/s for restrictive lung, and C = 50 mL/cmH2O and R = 20 cmH2O/L/s for obstructive lung. Muscle pressure was fixed at 25 cmH2O and respiratory rate at 20 bpm. Pressure support ventilation and continuous positive airway pressure were performed with each interface placed on a dummy head made of reinforced plastic that was connected to LUNGOO. We tested the inspiratory WOB difference between the interfaces with various combinations of ventilator settings (positive end-expiratory pressure 5 cmH2O; pressure support 0, 5, and 10 cmH2O). In the normal lung and restrictive lung models, WOB decreased more with the face-mask than the helmet, especially when accompanied by the level of pressure support. In the obstructive lung model, WOB with the helmet decreased compared with the other two interfaces. In the mixed lung model, there were no significant differences in WOB between the three interfaces. NPPV using a helmet is more effective than the other interfaces for WOB in obstructive lung disease.

Positive End-Expiratory Pressure and Variable Ventilation in Lung-Healthy Rats under General Anesthesia

PubMed Central

Camilo, Luciana M.; Ávila, Mariana B.; Cruz, Luis Felipe S.; Ribeiro, Gabriel C. M.; Spieth, Peter M.; Reske, Andreas A.; Amato, Marcelo; Giannella-Neto, Antonio; Zin, Walter A.; Carvalho, Alysson R.

2014-01-01

Objectives Variable ventilation (VV) seems to improve respiratory function in acute lung injury and may be combined with positive end-expiratory pressure (PEEP) in order to protect the lungs even in healthy subjects. We hypothesized that VV in combination with moderate levels of PEEP reduce the deterioration of pulmonary function related to general anesthesia. Hence, we aimed at evaluating the alveolar stability and lung protection of the combination of VV at different PEEP levels. Design Randomized experimental study. Setting Animal research facility. Subjects Forty-nine male Wistar rats (200–270 g). Interventions Animals were ventilated during 2 hours with protective low tidal volume (VT) in volume control ventilation (VCV) or VV and PEEP adjusted at the level of minimum respiratory system elastance (Ers), obtained during a decremental PEEP trial subsequent to a recruitment maneuver, and 2 cmH2O above or below of this level. Measurements and Main Results Ers, gas exchange and hemodynamic variables were measured. Cytokines were determined in lung homogenate and plasma samples and left lung was used for histologic analysis and diffuse alveolar damage scoring. A progressive time-dependent increase in Ers was observed independent on ventilatory mode or PEEP level. Despite of that, the rate of increase of Ers and lung tissue IL-1 beta concentration were significantly lower in VV than in VCV at the level of the PEEP of minimum Ers. A significant increase in lung tissue cytokines (IL-6, IL-1 beta, CINC-1 and TNF-alpha) as well as a ventral to dorsal and cranial to caudal reduction in aeration was observed in all ventilated rats with no significant differences among groups. Conclusions VV combined with PEEP adjusted at the level of the PEEP of minimal Ers seemed to better prevent anesthesia-induced atelectasis and might improve lung protection throughout general anesthesia. PMID:25383882

Lung protective mechanical ventilation strategies in cardiothoracic critical care: a retrospective study.

PubMed

Zochios, Vasileios; Hague, Matthew; Giraud, Kimberly; Jones, Nicola

2016-01-01

A body of evidence supports the use of low tidal volumes in ventilated patients without lung pathology to slow progress to acute respiratory distress syndrome (ARDS) due to ventilator associated lung injury. We undertook a retrospective chart review and tested the hypothesis that tidal volume is a predictor of mortality in cardiothoracic (medical and surgical) critical care patients receiving invasive mechanical ventilation. Independent predictors of mortality in our study included: type of surgery, albumin, H + , bilirubin, and fluid balance. In particular, it is important to note that cardiac, thoracic, and transplant surgical patients were associated with lower mortality. However, our study did not sample equally from The Berlin Definition of ARDS severity categories (mild, moderate, and severe hypoxemia). Although our study was not adequately powered to detect a difference in mortality between these groups, it will inform the development of a large prospective cohort study exploring the role of low tidal volume ventilation in cardiothoracic critically ill patients.

Lung Motion Model Validation Experiments, Free-Breathing Tissue Densitometry, and Ventilation Mapping using Fast Helical CT Imaging

NASA Astrophysics Data System (ADS)

Dou, Hsiang-Tai

The uncertainties due to respiratory motion present significant challenges to accurate characterization of cancerous tissues both in terms of imaging and treatment. Currently available clinical lung imaging techniques are subject to inferior image quality and incorrect motion estimation, with consequences that can systematically impact the downstream treatment delivery and outcome. The main objective of this thesis is the development of the techniques of fast helical computed tomography (CT) imaging and deformable image registration for the radiotherapy applications in accurate breathing motion modeling, lung tissue density modeling and ventilation imaging. Fast helical CT scanning was performed on 64-slice CT scanner using the shortest available gantry rotation time and largest pitch value such that scanning of the thorax region amounts to just two seconds, which is less than typical breathing cycle in humans. The scanning was conducted under free breathing condition. Any portion of the lung anatomy undergoing such scanning protocol would be irradiated for only a quarter second, effectively removing any motion induced image artifacts. The resulting CT data were pristine volumetric images that record the lung tissue position and density in a fraction of the breathing cycle. Following our developed protocol, multiple fast helical CT scans were acquired to sample the tissue positions in different breathing states. To measure the tissue displacement, deformable image registration was performed that registers the non-reference images to the reference one. In modeling breathing motion, external breathing surrogate signal was recorded synchronously with the CT image slices. This allowed for the tissue-specific displacement to be modeled as parametrization of the recorded breathing signal using the 5D lung motion model. To assess the accuracy of the motion model in describing tissue position change, the model was used to simulate the original high-pitch helical CT scan geometries, employed as ground truth data. Image similarity between the simulated and ground truth scans was evaluated. The model validation experiments were conducted in a patient cohort of seventeen patients to assess the model robustness and inter-patient variation. The model error averaged over multiple tracked positions from several breathing cycles was found to be on the order of one millimeter. In modeling the density change under free breathing condition, the determinant of Jacobian matrix from the registration-derived deformation vector field yielded volume change information of the lung tissues. Correlation of the Jacobian values to the corresponding voxel Housfield units (HU) reveals that the density variation for the majority of lung tissues can be very well described by mass conservation relationship. Different tissue types were identified and separately modeled. Large trials of validation experiments were performed. The averaged deviation between the modeled and the reference lung density was 30 HU, which was estimated to be the background CT noise level. In characterizing the lung ventilation function, a novel method was developed to determine the extent of lung tissue volume change. Information on volume change was derived from the deformable image registration of the fast helical CT images in terms of Jacobian values with respect to a reference image. Assuming the multiple volume change measurements are independently and identically distributed, statistical formulation was derived to model ventilation distribution of each lung voxels and empirical minimum and maximum probability distribution of the Jacobian values was computed. Ventilation characteristic was evaluated as the difference of the expectation value from these extremal distributions. The resulting ventilation map was compared with an independently obtained ventilation image derived directly from the lung intensities and good correlation was found using statistical test. In addition, dynamic ventilation characterization was investigated by estimating the voxel-specific ventilation distribution. Ventilation maps were generated at different percentile levels using the tissue volume expansion metrics.

Individualised perioperative open-lung approach versus standard protective ventilation in abdominal surgery (iPROVE): a randomised controlled trial.

PubMed

Ferrando, Carlos; Soro, Marina; Unzueta, Carmen; Suarez-Sipmann, Fernando; Canet, Jaume; Librero, Julián; Pozo, Natividad; Peiró, Salvador; Llombart, Alicia; León, Irene; India, Inmaculada; Aldecoa, Cesar; Díaz-Cambronero, Oscar; Pestaña, David; Redondo, Francisco J; Garutti, Ignacio; Balust, Jaume; García, Jose I; Ibáñez, Maite; Granell, Manuel; Rodríguez, Aurelio; Gallego, Lucía; de la Matta, Manuel; Gonzalez, Rafael; Brunelli, Andrea; García, Javier; Rovira, Lucas; Barrios, Francisco; Torres, Vicente; Hernández, Samuel; Gracia, Estefanía; Giné, Marta; García, María; García, Nuria; Miguel, Lisset; Sánchez, Sergio; Piñeiro, Patricia; Pujol, Roger; García-Del-Valle, Santiago; Valdivia, José; Hernández, María J; Padrón, Oto; Colás, Ana; Puig, Jaume; Azparren, Gonzalo; Tusman, Gerardo; Villar, Jesús; Belda, Javier

2018-03-01

The effects of individualised perioperative lung-protective ventilation (based on the open-lung approach [OLA]) on postoperative complications is unknown. We aimed to investigate the effects of intraoperative and postoperative ventilatory management in patients scheduled for abdominal surgery, compared with standard protective ventilation. We did this prospective, multicentre, randomised controlled trial in 21 teaching hospitals in Spain. We enrolled patients who were aged 18 years or older, were scheduled to have abdominal surgery with an expected time of longer than 2 h, had intermediate-to-high-risk of developing postoperative pulmonary complications, and who had a body-mass index less than 35 kg/m 2 . Patients were randomly assigned (1:1:1:1) online to receive one of four lung-protective ventilation strategies using low tidal volume plus positive end-expiratory pressure (PEEP): open-lung approach (OLA)-iCPAP (individualised intraoperative ventilation [individualised PEEP after a lung recruitment manoeuvre] plus individualised postoperative continuous positive airway pressure [CPAP]), OLA-CPAP (intraoperative individualised ventilation plus postoperative CPAP), STD-CPAP (standard intraoperative ventilation plus postoperative CPAP), or STD-O 2 (standard intraoperative ventilation plus standard postoperative oxygen therapy). Patients were masked to treatment allocation. Investigators were not masked in the operating and postoperative rooms; after 24 h, data were given to a second investigator who was masked to allocations. The primary outcome was a composite of pulmonary and systemic complications during the first 7 postoperative days. We did the primary analysis using the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02158923. Between Jan 2, 2015, and May 18, 2016, we enrolled 1012 eligible patients. Data were available for 967 patients, whom we included in the final analysis. Risk of pulmonary and systemic complications did not differ for patients in OLA-iCPAP (110 [46%] of 241, relative risk 0·89 [95% CI 0·74-1·07; p=0·25]), OLA-CPAP (111 [47%] of 238, 0·91 [0·76-1·09; p=0·35]), or STD-CPAP groups (118 [48%] of 244, 0·95 [0·80-1·14; p=0·65]) when compared with patients in the STD-O 2 group (125 [51%] of 244). Intraoperatively, PEEP was increased in 69 (14%) of patients in the standard perioperative ventilation groups because of hypoxaemia, and no patients from either of the OLA groups required rescue manoeuvres. In patients who have major abdominal surgery, the different perioperative open lung approaches tested in this study did not reduce the risk of postoperative complications when compared with standard lung-protective mechanical ventilation. Instituto de Salud Carlos III of the Spanish Ministry of Economy and Competitiveness, and Grants Programme of the European Society of Anaesthesiology. Copyright © 2018 Elsevier Ltd. All rights reserved.

WE-FG-206-07: Assessing the Lung Function of Patients with Non-Small Cell Lung Cancer Using Hyperpolarized Xenon-129 Dissolved-Phase MRI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qing, K; Mugler, J; Chen, Q

Purpose: Hyperpolarized xenon-129 dissolved-phase MRI is the first imaging technique that allows 3-dimensional regional mapping of ventilation and gas uptake by tissue and blood the in human lung. Multiple outcome measures can be produced from this method. Existing studies in subjects with major lung diseases compared to healthy controls demonstrated high sensitivities of this method to pulmonary physiological factors including ventilation, alveolar tissue density, surface-to-volume ratio, pulmonary perfusion and gas-blood barrier thickness. The purpose of this study is to evaluate the utility of this new imaging tool to assess the lung function in patients with non-small cell lung cancer (NSCLC).more » Methods: Ten healthy controls (age: 63±10) and five patients (age: 62±13) with NSCLC underwent the xenon-129 dissolved-phase MRI, pulmonary function test (PFT) and CT for clinical purpose. Three outcome measures were produced from xenon-129 dissolved-phase MRI, including ventilation defect fraction (Vdef%) reflecting the airflow obstruction, tissue-to-gas ratio reflecting lung tissue density, and RBC-to-tissue ratio reflecting pulmonary perfusion and gas exchange. Results: Compared to healthy controls, patients with NSCLC showed more ventilation defects (NSCLC: 22±6%; control: 40±18%; P=0.01), lower tissue-to-gas (NSCLC: 0.82±0.31%; control: 1.07±0.13%; P=0.05) and RBC-to-tissue ratios (NSCLC: 0.82±0.31%; control: 1.07±0.13%; P=0.01). Maps for ventilation and gas uptake by tissue and blood were highly heterogeneous in the lungs of patients. Vdef% and RBC-to-tissue ratios in all 15 subjects correlated with corresponding global lung functional measures from PFT: FEV1/FVC (R=−0.91, P<0.001) and DLCO % predicted (R=0.54, P=0.03), respectively. The tissue-to-gas ratios correlated with tissue density (HU) measured by CT (R=0.88, P<0.001). Conclusion: With the unique ability to provide detailed information about lung function including ventilation, tissue density, perfusion and gas exchange with 3D resolution, hyperpolarized xenon-129 dissolved-phase MRI has high potential to be used as an important reference for radiotherapy treatment planning and for evaluating the side effects of the treatment. Receive research support and funding from Siemens.« less

Mechanical Ventilation–associated Lung Fibrosis in Acute Respiratory Distress Syndrome A Significant Contributor to Poor Outcome

PubMed Central

Cabrera-Benitez, Nuria E.; Laffey, John G.; Parotto, Matteo; Spieth, Peter M.; Villar, Jesús; Zhang, Haibo; Slutsky, Arthur S.

2016-01-01

One of the most challenging problems in critical care medicine is the management of patients with the acute respiratory distress syndrome. Increasing evidence from experimental and clinical studies suggests that mechanical ventilation, which is necessary for life support in patients with acute respiratory distress syndrome, can cause lung fibrosis, which may significantly contribute to morbidity and mortality. The role of mechanical stress as an inciting factor for lung fibrosis versus its role in lung homeostasis and the restoration of normal pulmonary parenchymal architecture is poorly understood. In this review, the authors explore recent advances in the field of pulmonary fibrosis in the context of acute respiratory distress syndrome, concentrating on its relevance to the practice of mechanical ventilation, as commonly applied by anesthetists and intensivists. The authors focus the discussion on the thesis that mechanical ventilation—or more specifically, that ventilator-induced lung injury—may be a major contributor to lung fibrosis. The authors critically appraise possible mechanisms underlying the mechanical stress–induced lung fibrosis and highlight potential therapeutic strategies to mitigate this fibrosis. PMID:24732023

Comparison of flow and gas washout characteristics between pressure control and high-frequency percussive ventilation using a test lung

PubMed Central

Dutta, Rabijit; Xing, Tao; Swanson, Craig; Heltborg, Jeff; Murdoch, Gordon K

2018-01-01

Objective A comparison between flow and gas washout data for high-frequency percussive ventilation (HFPV) and pressure control ventilation (PCV) under similar conditions is currently not available. This bench study aims to compare and describe the flow and gas washout behavior of HFPV and PCV in a newly designed experimental setup and establish a framework for future clinical and animal studies. Approach We studied gas washout behavior using a newly designed experimental setup that is motivated by the multi-breath nitrogen washout measurements. In this procedure, a test lung was filled with nitrogen gas before it was connected to a ventilator. Pressure, volume, and oxygen concentrations were recorded under different compliance and resistance conditions. PCV was compared with two settings of HFPV, namely, HFPV-High and HFPV-Low, to simulate the different variations in its clinical application. In the HFPV-Low mode, the peak pressures and drive pressures of HFPV and PCV are matched, whereas in the HFPV-High mode, the mean airway pressures (MAP) are matched. Main results HFPV-Low mode delivers smaller tidal volume (VT) as compared to PCV under all lung conditions, whereas HFPV-High delivers a larger VT. HFPV-High provides rapid washout as compared to PCV under all lung conditions. HFPV-Low takes a longer time to wash out nitrogen except at a low compliance, where it expedites washout at a smaller VT and MAP compared to PCV washout. Significance Various flow parameters for HFPV and PCV are mathematically defined. A shorter washout time at a small VT in low compliant test lungs for HFPV could be regarded as a hypothesis for lung protective ventilation for animal or human lungs. PMID:29369819

Comparison of flow and gas washout characteristics between pressure control and high-frequency percussive ventilation using a test lung.

PubMed

Dutta, Rabijit; Xing, Tao; Swanson, Craig; Heltborg, Jeff; Murdoch, Gordon K

2018-03-15

A comparison between flow and gas washout data for high-frequency percussive ventilation (HFPV) and pressure control ventilation (PCV) under similar conditions is currently not available. This bench study aims to compare and describe the flow and gas washout behavior of HFPV and PCV in a newly designed experimental setup and establish a framework for future clinical and animal studies. We studied gas washout behavior using a newly designed experimental setup that is motivated by the multi-breath nitrogen washout measurements. In this procedure, a test lung was filled with nitrogen gas before it was connected to a ventilator. Pressure, volume, and oxygen concentrations were recorded under different compliance and resistance conditions. PCV was compared with two settings of HFPV, namely, HFPV-High and HFPV-Low, to simulate the different variations in its clinical application. In the HFPV-Low mode, the peak pressures and drive pressures of HFPV and PCV are matched, whereas in the HFPV-High mode, the mean airway pressures (MAP) are matched. HFPV-Low mode delivers smaller tidal volume (V T ) as compared to PCV under all lung conditions, whereas HFPV-High delivers a larger V T . HFPV-High provides rapid washout as compared to PCV under all lung conditions. HFPV-Low takes a longer time to wash out nitrogen except at a low compliance, where it expedites washout at a smaller V T and MAP compared to PCV washout. Various flow parameters for HFPV and PCV are mathematically defined. A shorter washout time at a small V T in low compliant test lungs for HFPV could be regarded as a hypothesis for lung protective ventilation for animal or human lungs.

Scintigraphic results in patients with lung transplants: a prospective comparative study.

PubMed

Humplik, B I; Sandrock, D; Aurisch, R; Richter, W-St; Ewert, R; Munz, D L

2005-04-01

We addressed the feasibility of scintigraphy in the postoperative monitoring of lung transplants. 37 patients (22 women, 15 men, 37 +/- 15 years) in good clinical condition were examined after lung transplantation. Scintigraphic procedures for assessing ventilation (133Xe), perfusion (99mTc microspheres) and aerosol-inhalation (99mTc aerosol) were performed for all patients. The findings were compared with those of established diagnostic modalities. All lung transplants showed homogeneous ventilation but with a non-physiologic difference of over 20% between both pulmonary lobes in one-third of the cases. There was a difference between the impairement of perfusion and ventilation in the presence of an impaired Euler-Liljestrand reflex in 14/37 (38%) patients. Furthermore, bronchoscopy and aerosol-inhalation scans often did not correlate, e. g. a bronchoscopically evident stenosis was not necessarily associated with an increased activity, and vice versa. Although peripheral mucociliary clearance was preserved after transplantation, stasis in central airways resulted in significantly impaired global clearance. Ventilation and perfusion scintigraphy reveal in a significant number of lung recipients pathologic findings and therefore can be recommended for postoperative monitoring. From a clinical point of view aerosol-inhalation scintigraphy (clearance) is not of any additional value.

Non-contrast-enhanced perfusion and ventilation assessment of the human lung by means of fourier decomposition in proton MRI.

PubMed

Bauman, Grzegorz; Puderbach, Michael; Deimling, Michael; Jellus, Vladimir; Chefd'hotel, Christophe; Dinkel, Julien; Hintze, Christian; Kauczor, Hans-Ulrich; Schad, Lothar R

2009-09-01

Assessment of regional lung perfusion and ventilation has significant clinical value for the diagnosis and follow-up of pulmonary diseases. In this work a new method of non-contrast-enhanced functional lung MRI (not dependent on intravenous or inhalative contrast agents) is proposed. A two-dimensional (2D) true fast imaging with steady precession (TrueFISP) pulse sequence (TR/TE = 1.9 ms/0.8 ms, acquisition time [TA] = 112 ms/image) was implemented on a 1.5T whole-body MR scanner. The imaging protocol comprised sets of 198 lung images acquired with an imaging rate of 3.33 images/s in coronal and sagittal view. No electrocardiogram (ECG) or respiratory triggering was used. A nonrigid image registration algorithm was applied to compensate for respiratory motion. Rapid data acquisition allowed observing intensity changes in corresponding lung areas with respect to the cardiac and respiratory frequencies. After a Fourier analysis along the time domain, two spectral lines corresponding to both frequencies were used to calculate the perfusion- and ventilation-weighted images. The described method was applied in preliminary studies on volunteers and patients showing clinical relevance to obtain non-contrast-enhanced perfusion and ventilation data.

Ventilatory protective strategies during thoracic surgery: effects of alveolar recruitment maneuver and low-tidal volume ventilation on lung density distribution.

PubMed

Kozian, Alf; Schilling, Thomas; Schütze, Hartmut; Senturk, Mert; Hachenberg, Thomas; Hedenstierna, Göran

2011-05-01

The increased tidal volume (V(T)) applied to the ventilated lung during one-lung ventilation (OLV) enhances cyclic alveolar recruitment and mechanical stress. It is unknown whether alveolar recruitment maneuvers (ARMs) and reduced V(T) may influence tidal recruitment and lung density. Therefore, the effects of ARM and OLV with different V(T) on pulmonary gas/tissue distribution are examined. Eight anesthetized piglets were mechanically ventilated (V(T) = 10 ml/kg). A defined ARM was applied to the whole lung (40 cm H(2)O for 10 s). Spiral computed tomographic lung scans were acquired before and after ARM. Thereafter, the lungs were separated with an endobronchial blocker. The pigs were randomized to receive OLV in the dependent lung with a V(T) of either 5 or 10 ml/kg. Computed tomography was repeated during and after OLV. The voxels were categorized by density intervals (i.e., atelectasis, poorly aerated, normally aerated, or overaerated). Tidal recruitment was defined as the addition of gas to collapsed lung regions. The dependent lung contained atelectatic (56 ± 10 ml), poorly aerated (183 ± 10 ml), and normally aerated (187 ± 29 ml) regions before ARM. After ARM, lung volume and aeration increased (426 ± 35 vs. 526 ± 69 ml). Respiratory compliance enhanced, and tidal recruitment decreased (95% vs. 79% of the whole end-expiratory lung volume). OLV with 10 ml/kg further increased aeration (atelectasis, 15 ± 2 ml; poorly aerated, 94 ± 24 ml; normally aerated, 580 ± 98 ml) and tidal recruitment (81% of the dependent lung). OLV with 5 ml/kg did not affect tidal recruitment or lung density distribution. (Data are given as mean ± SD.) The ARM improves aeration and respiratory mechanics. In contrast to OLV with high V(T), OLV with reduced V(T) does not reinforce tidal recruitment, indicating decreased mechanical stress.

Contrasting effects of lower body positive pressure on upper airways resistance and partial pressure of carbon dioxide in men with heart failure and obstructive or central sleep apnea.

PubMed

Kasai, Takatoshi; Motwani, Shveta S; Yumino, Dai; Gabriel, Joseph M; Montemurro, Luigi Taranto; Amirthalingam, Vinoban; Floras, John S; Bradley, T Douglas

2013-03-19

This study sought to test the effects of rostral fluid displacement from the legs on transpharyngeal resistance (Rph), minute volume of ventilation (Vmin), and partial pressure of carbon dioxide (PCO2) in men with heart failure (HF) and either obstructive (OSA) or central sleep apnea (CSA). Overnight rostral fluid shift relates to severity of OSA and CSA in men with HF. Rostral fluid displacement may facilitate OSA if it shifts into the neck and increases Rph, because pharyngeal obstruction causes OSA. Rostral fluid displacement may also facilitate CSA if it shifts into the lungs and induces reflex augmentation of ventilation and reduces PCO2, because a decrease in PCO2 below the apnea threshold causes CSA. Men with HF were divided into those with mainly OSA (obstructive-dominant, n = 18) and those with mainly CSA (central-dominant, n = 10). While patients were supine, antishock trousers were deflated (control) or inflated for 15 min (lower body positive pressure [LBPP]) in random order. LBPP reduced leg fluid volume and increased neck circumference in both obstructive- and central-dominant groups. However, in contrast to the obstructive-dominant group in whom LBPP induced an increase in Rph, a decrease in Vmin, and an increase in PCO2, in the central-dominant group, LBPP induced a reduction in Rph, an increase in Vmin, and a reduction in PCO2. These findings suggest mechanisms by which rostral fluid shift contributes to the pathogenesis of OSA and CSA in men with HF. Rostral fluid shift could facilitate OSA if it induces pharyngeal obstruction, but could also facilitate CSA if it augments ventilation and lowers PCO2. Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

WE-AB-202-01: Evaluating the Toxicity Reduction with CT-Ventilation Functional Avoidance Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vinogradskiy, Y; Miyasaka, Y; Kadoya, N

Purpose: CT-ventilation is an exciting new imaging modality that uses 4DCTs to calculate lung ventilation. Studies have proposed to use 4DCT-ventilation imaging for functional avoidance radiotherapy which implies designing treatment plans to spare functional portions of the lung. Although retrospective studies have been performed to evaluate the dosimetric gains to functional lung; no work has been done to translate the dosimetric gains to an improvement in pulmonary toxicity. The purpose of our work was to evaluate the potential reduction in toxicity for 4DCT-ventilation based functional avoidance. Methods: 70 lung cancer patients with 4DCT imaging were used for the study. CT-ventilationmore » maps were calculated using the patient’s 4DCT, deformable image registrations, and a density-change-based algorithm. Radiation pneumonitis was graded using imaging and clinical information. Log-likelihood methods were used to fit a normal-tissue-complication-probability (NTCP) model predicting grade 2+ radiation pneumonitis as a function of doses (mean and V20) to functional lung (>15% ventilation). For 20 patients a functional plan was generated that reduced dose to functional lung while meeting RTOG 0617-based constraints. The NTCP model was applied to the functional plan to determine the reduction in toxicity with functional planning Results: The mean dose to functional lung was 16.8 and 17.7 Gy with the functional and clinical plans respectively. The corresponding grade 2+ pneumonitis probability was 26.9% with the clinically-used plan and 24.6% with the functional plan (8.5% reduction). The V20-based grade 2+ pneumonitis probability was 23.7% with the clinically-used plan and reduced to 19.6% with the functional plan (20.9% reduction). Conclusion: Our results revealed a reduction of 9–20% in complication probability with functional planning. To our knowledge this is the first study to apply complication probability to convert dosimetric results to toxicity improvement. The results presented in the current work provide seminal data for prospective clinical trials in functional avoidance. YV discloses funding from State of Colorado. TY discloses National Lung Cancer Partnership; Young Investigator Research grant.« less

Delivery of tidal volume from four anaesthesia ventilators during volume-controlled ventilation: a bench study.

PubMed

Wallon, G; Bonnet, A; Guérin, C

2013-06-01

Tidal volume (V(T)) must be accurately delivered by anaesthesia ventilators in the volume-controlled ventilation mode in order for lung protective ventilation to be effective. However, the impact of fresh gas flow (FGF) and lung mechanics on delivery of V(T) by the newest anaesthesia ventilators has not been reported. We measured delivered V(T) (V(TI)) from four anaesthesia ventilators (Aisys™, Flow-i™, Primus™, and Zeus™) on a pneumatic test lung set with three combinations of lung compliance (C, ml cm H2O(-1)) and resistance (R, cm H2O litre(-1) s(-2)): C60R5, C30R5, C60R20. For each CR, three FGF rates (0.5, 3, 10 litre min(-1)) were investigated at three set V(T)s (300, 500, 800 ml) and two values of PEEP (0 and 10 cm H2O). The volume error = [(V(TI) - V(Tset))/V(Tset)] ×100 was computed in body temperature and pressure-saturated conditions and compared using analysis of variance. For each CR and each set V(T), the absolute value of the volume error significantly declined from Aisys™ to Flow-i™, Zeus™, and Primus™. For C60R5, these values were 12.5% for Aisys™, 5% for Flow-i™ and Zeus™, and 0% for Primus™. With an increase in FGF, absolute values of the volume error increased only for Aisys™ and Zeus™. However, in C30R5, the volume error was minimal at mid-FGF for Aisys™. The results were similar at PEEP 10 cm H2O. Under experimental conditions, the volume error differed significantly between the four new anaesthesia ventilators tested and was influenced by FGF, although this effect may not be clinically relevant.

Improved lung recruitment and oxygenation during mandatory ventilation with a new expiratory ventilation assistance device: A controlled interventional trial in healthy pigs.

PubMed

Schmidt, Johannes; Wenzel, Christin; Mahn, Marlene; Spassov, Sashko; Cristina Schmitz, Heidi; Borgmann, Silke; Lin, Ziwei; Haberstroh, Jörg; Meckel, Stephan; Eiden, Sebastian; Wirth, Steffen; Buerkle, Hartmut; Schumann, Stefan

2018-05-04

In contrast to conventional mandatory ventilation, a new ventilation mode, expiratory ventilation assistance (EVA), linearises the expiratory tracheal pressure decline. We hypothesised that due to a recruiting effect, linearised expiration oxygenates better than volume controlled ventilation (VCV). We compared the EVA with VCV mode with regard to gas exchange, ventilation volumes and pressures and lung aeration in a model of peri-operative mandatory ventilation in healthy pigs. Controlled interventional trial. Animal operating facility at a university medical centre. A total of 16 German Landrace hybrid pigs. The lungs of anaesthetised pigs were ventilated with the EVA mode (n=9) or VCV (control, n=7) for 5 h with positive end-expiratory pressure of 5 cmH2O and tidal volume of 8 ml kg. The respiratory rate was adjusted for a target end-tidal CO2 of 4.7 to 6 kPa. Tracheal pressure, minute volume and arterial blood gases were recorded repeatedly. Computed thoracic tomography was performed to quantify the percentages of normally and poorly aerated lung tissue. Two animals in the EVA group were excluded due to unstable ventilation (n=1) or unstable FiO2 delivery (n=1). Mean tracheal pressure and PaO2 were higher in the EVA group compared with control (mean tracheal pressure: 11.6 ± 0.4 versus 9.0 ± 0.3 cmH2O, P < 0.001 and PaO2: 19.2 ± 0.7 versus 17.5 ± 0.4 kPa, P = 0.002) with comparable peak inspiratory tracheal pressure (18.3 ± 0.9 versus 18.0 ± 1.2 cmH2O, P > 0.99). Minute volume was lower in the EVA group compared with control (5.5 ± 0.2 versus 7.0 ± 1.0 l min, P = 0.02) with normoventilation in both groups (PaCO2 5.4 ± 0.3 versus 5.5 ± 0.3 kPa, P > 0.99). In the EVA group, the percentage of normally aerated lung tissue was higher (81.0 ± 3.6 versus 75.8 ± 3.0%, P = 0.017) and of poorly aerated lung tissue lower (9.5 ± 3.3 versus 15.7 ± 3.5%, P = 0.002) compared with control. EVA ventilation improves lung aeration via elevated mean tracheal pressure and consequently improves arterial oxygenation at unaltered positive end-expiratory pressure (PEEP) and peak inspiratory pressure (PIP). These findings suggest the EVA mode is a new approach for protective lung ventilation.This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0.

Ventilation in the patient with unilateral lung disease.

PubMed

Thomas, A R; Bryce, T L

1998-10-01

Severe ULD presents a challenge in ventilator management because of the marked asymmetry in the mechanics of the two lungs. The asymmetry may result from significant decreases or increases in the compliance of the involved lung. Traditional ventilator support may fail to produce adequate gas exchange in these situations and has the potential to cause further deterioration. Fortunately, conventional techniques can be safely and effectively applied in the majority of cases without having to resort to less familiar and potentially hazardous forms of support. In those circumstances when conventional ventilation is unsuccessful in restoring adequate gas exchange, lateral positioning and ILV have proved effective at improving and maintaining gas exchange. Controlled trials to guide clinical decision making are lacking. In patients who have processes associated with decreased compliance in the involved lung, lateral positioning may be a simple method of improving gas exchange but is associated with many practical limitations. ILV in these patients is frequently successful when differential PEEP is applied with the higher pressure to the involved lung. In patients in whom the pathology results in distribution of ventilation favoring the involved lung, particularly BPF, ILV can be used to supply adequate support while minimizing flow through the fistula and allowing it to close. The application of these techniques should be undertaken with an understanding of the pathophysiology of the underlying process; the reported experience with these techniques, including indications and successfully applied methods; and the potential problems encountered with their use. Fortunately, these modalities are infrequently required, but they provide a critical means of support when conventional techniques fail.

Regional volume changes in canine lungs suspended in air

NASA Technical Reports Server (NTRS)

Abbrecht, Peter H.; Kyle, Richard R.; Bryant, Howard J.; Feuerstein, Irwin

1995-01-01

The purpose of this study was to determine the effect of the absence of a pleural pressure gradient (simulating the presumed condition found in microgravity) upon regional expansion of the lung. We attempted to produce a uniform pressure over the surface of the lung by suspending excised lungs in air. Such studies should help determine whether or not the absence of a pleural pressure gradient leads to uniform ventilation. A preparation in which there is no pleural pressure gradient should also be useful in studying non-gravitational effects on ventilation distribution.

Amiodarone causes acute oxidant lung injury in ventilated and perfused rabbit lungs.

PubMed

Kennedy, T P; Gordon, G B; Paky, A; McShane, A; Adkinson, N F; Peters, S P; Friday, K; Jackman, W; Sciuto, A M; Gurtner, G H

1988-07-01

Amiodarone (ADR), a new antiarrhythmic drug for life-threatening cardiac arrhythmias, causes pneumonitis or lung fibrosis in a sizeable minority of patients. The cause of lung damage is not known. We have shown that infusion of 10 mg amiodarone into the inflow circuit of ventilated and perfused rabbit lungs causes immediate increase in pulmonary artery pressure (mean +/- SEM) (from 13.6 +/- 1.2 to 40.6 +/- 9.5 mm Hg, p less than 0.01) and pulmonary edema with marked increase in the pulmonary generation of thromboxane and leukotrienes C4 and/or D4. Albumin (2 g%) in the perfusate prevents any increase in lung perfusion pressure or edema formation. When lung perfusion pressure increase is blocked with the combined cyclooxygenase and lipoxygenase inhibitor enolicam sodium (CG5391B, 35 microM in perfusate), significant lung edema still occurs after amiodarone, indicating that amiodarone causes increased alveolar-capillary membrane permeability. Addition of catalase (100 U/ml) or superoxide dismutase and catalase (100 U/ml each) to perfusate fails to protect from amiodarone lung injury. Immediate infusion of amiodarone (10 mg) into lungs ventilated with room air (ADR + RA) causes an increase in lung weight gain from baseline (delta W) of 5.7 +/- 1.5 g/min. Compared with ADR + RA, ventilation of lungs with 4% O2 (delta W = 0.7 +/- 0.3 g/min, p less than 0.05), pretreatment of rabbits for 3 days with butylated hydroxyanisole (BHA, 100 mg/kg/day i.p., delta W = 0.05 +/- 0.02 g/min, p less than 0.01), pretreatment of rabbits for 3 days with vitamin E (Vit E, 300 U/day orally, delta W = 0.6 +/- 0.2 g/min, p less than 0.05), or addition of N-acetylcysteine to the lung perfusate (NAC, 5 mM, delta W = 0.1 +/- 0.08 g/min, p less than 0.01) all protect from lung edema formation after amiodarone. Amiodarone (100 mg) also caused a marked increase in luminol-enhanced lung chemiluminescence, lung production of superoxide anion (O2-), and tissue levels of lung glutathione disulfide. These results suggest that amiodarone causes lung injury by an oxidant mechanism.

Integrated Stress Response Mediates Epithelial Injury in Mechanical Ventilation.

PubMed

Dolinay, Tamas; Himes, Blanca E; Shumyatcher, Maya; Lawrence, Gladys Gray; Margulies, Susan S

2017-08-01

Ventilator-induced lung injury (VILI) is a severe complication of mechanical ventilation that can lead to acute respiratory distress syndrome. VILI is characterized by damage to the epithelial barrier with subsequent pulmonary edema and profound hypoxia. Available lung-protective ventilator strategies offer only a modest benefit in preventing VILI because they cannot impede alveolar overdistension and concomitant epithelial barrier dysfunction in the inflamed lung regions. There are currently no effective biochemical therapies to mitigate injury to the alveolar epithelium. We hypothesize that alveolar stretch activates the integrated stress response (ISR) pathway and that the chemical inhibition of this pathway mitigates alveolar barrier disruption during stretch and mechanical ventilation. Using our established rat primary type I-like alveolar epithelial cell monolayer stretch model and in vivo rat mechanical ventilation that mimics the alveolar overdistension seen in acute respiratory distress syndrome, we studied epithelial responses to mechanical stress. Our studies revealed that the ISR signaling pathway is a key modulator of epithelial permeability. We show that prolonged epithelial stretch and injurious mechanical ventilation activate the ISR, leading to increased alveolar permeability, cell death, and proinflammatory signaling. Chemical inhibition of protein kinase RNA-like endoplasmic reticulum kinase, an upstream regulator of the pathway, resulted in decreased injury signaling and improved barrier function after prolonged cyclic stretch and injurious mechanical ventilation. Our results provide new evidence that therapeutic targeting of the ISR can mitigate VILI.

Effect of PEEP and inhaled nitric oxide on pulmonary gas exchange during gaseous and partial liquid ventilation with small volumes of perfluorocarbon.

PubMed

Max, M; Kuhlen, R; Falter, F; Reyle-Hahn, M; Dembinski, R; Rossaint, R

2000-04-01

Partial liquid ventilation, positive end-expiratory pressure (PEEP) and inhaled nitric oxide (NO) can improve ventilation/perfusion mismatch in acute lung injury (ALI). The aim of the present study was to compare gas exchange and hemodynamics in experimental ALI during gaseous and partial liquid ventilation at two different levels of PEEP, with and without the inhalation of nitric oxide. Seven pigs (24+/-2 kg BW) were surfactant-depleted by repeated lung lavage with saline. Gas exchange and hemodynamic parameters were assessed in all animals during gaseous and subsequent partial liquid ventilation at two levels of PEEP (5 and 15 cmH2O) and intermittent inhalation of 10 ppm NO. Arterial oxygenation increased significantly with a simultaneous decrease in cardiac output when PEEP 15 cmH2O was applied during gaseous and partial liquid ventilation. All other hemodynamic parameters revealed no relevant changes. Inhalation of NO and instillation of perfluorocarbon had no additive effects on pulmonary gas exchange when compared to PEEP 15 cmH2O alone. In experimental lung injury, improvements in gas exchange are most distinct during mechanical ventilation with PEEP 15 cmH2O without significantly impairing hemodynamics. Partial liquid ventilation and inhaled NO did not cause an additive increase of PaO2.

Intraoperative mechanical ventilation: state of the art.

PubMed

Ball, Lorenzo; Costantino, Federico; Orefice, Giulia; Chandrapatham, Karthikka; Pelosi, Paolo

2017-10-01

Mechanical ventilation is a cornerstone of the intraoperative management of the surgical patient and is still mandatory in several surgical procedures. In the last decades, research focused on preventing postoperative pulmonary complications (PPCs), both improving risk stratification through the use of predictive scores and protecting the lung adopting so-called protective ventilation strategies. The aim of this review was to give an up-to-date overview of the currently suggested intraoperative ventilation strategies, along with their pathophysiologic rationale, with a focus on challenging conditions, such as obesity, one-lung ventilation and cardiopulmonary bypass. While anesthesia and mechanical ventilation are becoming increasingly safe practices, the contribution to surgical mortality attributable to postoperative lung injury is not negligible: for these reasons, the prevention of PPCs, including the use of protective mechanical ventilation is mandatory. Mechanical ventilation should be optimized providing an adequate respiratory support while minimizing unwanted negative effects. Due to the high number of surgical procedures performed daily, the impact on patients' health and healthcare costs can be relevant, even when new strategies result in an apparently small improvement of outcome. A protective intraoperative ventilation should include a low tidal volume of 6-8 mL/kg of predicted body weight, plateau pressures ideally below 16 cmH2O, the lowest possible driving pressure, moderate-low PEEP levels except in obese patients, laparoscopy and long surgical procedures that might benefit of a slightly higher PEEP. The work of the anesthesiologist should start with a careful preoperative visit to assess the risk, and a close postoperative monitoring.

Effects of vascular flow and PEEP in a multiple hit model of lung injury in isolated perfused rabbit lungs.

PubMed

Piacentini, Enrique; López-Aguilar, Josefina; García-Martín, Carolina; Villagrá, Ana; Saenz-Valiente, Alicia; Murias, Gastón; Fernández-Segoviano, Pilar; Hotchkiss, John R; Blanch, Lluis

2008-07-01

High vascular flow aggravates lung damage in animal models of ventilator-induced lung injury. Positive end-expiratory pressure (PEEP) can attenuate ventilator-induced lung injury, but its continued effectiveness in the setting of antecedent lung injury is unclear. The objective of the present study was to evaluate whether the application of PEEP diminishes lung injury induced by concurrent high vascular flow and high alveolar pressures in normal lungs and in a preinjury lung model. Two series of experiments were performed. Fifteen sets of isolated rabbit lungs were randomized into three groups (n = 5): low vascular flow/low PEEP; high vascular flow/low PEEP, and high vascular flow/high PEEP. Subsequently, the same protocol was applied in an additional 15 sets of isolated rabbit lungs in which oleic acid was added to the vascular perfusate to produce mild to moderate lung injury. All lungs were ventilated with peak airway pressure of 30 cm H2O for 30 minutes. Outcome measures included frequency of gross structural failure, pulmonary hemorrhage, edema formation, changes in static compliance, pulmonary vascular resistance, and pulmonary ultrafiltration coefficient. In the context of high vascular flow, application of a moderate level of PEEP reduced pulmonary rupture, edema formation, and lung hemorrhage. The protective effects of PEEP were not observed in lungs concurrently injured with oleic acid. Under these experimental conditions, PEEP attenuates lung injury in the setting of high vascular flow. The protective effect of PEEP is lost in a two-hit model of lung injury.

Assessing Respiratory System Mechanical Function.

PubMed

Restrepo, Ruben D; Serrato, Diana M; Adasme, Rodrigo

2016-12-01

The main goals of assessing respiratory system mechanical function are to evaluate the lung function through a variety of methods and to detect early signs of abnormalities that could affect the patient's outcomes. In ventilated patients, it has become increasingly important to recognize whether respiratory function has improved or deteriorated, whether the ventilator settings match the patient's demand, and whether the selection of ventilator parameters follows a lung-protective strategy. Ventilator graphics, esophageal pressure, intra-abdominal pressure, and electric impedance tomography are some of the best-known monitoring tools to obtain measurements and adequately evaluate the respiratory system mechanical function. Copyright © 2016 Elsevier Inc. All rights reserved.

Krypton-81m ventilation scanning: acute respiratory disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lavender, J.P.; Irving, H.; Armstrong, J.D. II

1981-02-01

From experience with 700 patients undergoing ventilation and perfusion lung scanning with krypton-81m/technetium-99m technique, 34 patients suffering from nonembolic acute respiratory disease were selected for review. In 16 patients with pneumonia, all had defects of ventilation corresponding to, or larger than, the radiologic consolidation. In 13 patients there was some preservation of perfusion in the consolidated region. In two of the three patients with matched defects, the pneumonia was of long standing. In seven patients with collapse or atelectasis and in 11 patients with acute reversible bronchial obstruction and normal volume lungs, a similar pattern or ventillation and perfusion wasmore » observed.« less

Mechanical delivery of aerosolized gadolinium-DTPA for pulmonary ventilation assessment in MR imaging.

PubMed

Haage, P; Adam, G; Karaagac, S; Pfeffer, J; Glowinski, A; Döhmen, S; Günther, R W

2001-04-01

To evaluate a new technique with mechanical administration of aerosolized gadolinium (Gd)-DTPA for MR visualization of lung ventilation. Ten experimental procedures were performed in six domestic pigs. Gd-DTPA was aerosolized by a small-particle generator. The intubated animals were mechanically aerosolized with the nebulized contrast agent and studied on a 1.5-T MR imager. Respiratory gated T1-weighted turbo spin-echo images were obtained before, during, and after contrast administration. Pulmonary signal intensity (SI) changes were calculated for corresponding regions of both lungs. Homogeneity of aerosol distribution was graded independently by two radiologists. To achieve a comparable SI increase as attained in previous trials that used manual aerosol ventilation, a ventilation period of 20 minutes (formerly 30 minutes) was sufficient. Mean SI changes of 116% were observed after that duration. Contrast delivery was rated evenly distributed in all cases by the reviewers. The feasibility of applying Gd-DTPA as a contrast agent to demonstrate pulmonary ventilation in large animals has been described before. The results of this refined technique substantiate the potential of Gd-based ventilation MR imaging by improving aerosol distribution and shortening the nebulization duration in the healthy lung.

The effect of lung-size mismatch on mechanical ventilation tidal volumes after bilateral lung transplantation.

PubMed

Dezube, Rebecca; Arnaoutakis, George J; Reed, Robert M; Bolukbas, Servet; Shah, Ashish S; Orens, Jonathan B; Brower, Roy G; Eberlein, Michael

2013-03-01

Mechanical ventilation tidal volumes are usually set according to an estimate of patient size in millilitres (ml) per kilogram (kg) body weight. We describe the relationship between donor-recipient lung-size mismatch and postoperative mechanical ventilation tidal volumes according to recipient- and donor-predicted body weights in a cohort of bilateral lung transplant patients. A most-undersized (10 patients with lowest predicted total lung capacity [pTLC] ratio = pTLC-donor/pTLC-recipient), a most-oversized (10 patients with highest pTLC ratio) and best-matched subset (10 patients with predicted total lung capacity ratio closest to 1.0) were selected within a cohort of 70 patients. All tidal volumes during mechanical ventilation in the first 96 h after bilateral lung transplantation were recorded. Tidal volumes were expressed in ml and ml/kg-recipient-predicted body weights and ml/kg-donor-predicted body weights. Postoperative absolute tidal volumes (in ml) were comparable between subsets of patients with undersized, matched and oversized allografts (552 ± 103 vs 581 ± 107 vs 582 ± 104 ml), and tidal volumes in ml/kg-recipient-predicted body weights were also similar (8.8 ± 1.4 vs 9.3 ± 1.1 vs 9.8 ± 2.1). However, tidal volumes in ml/kg-donor-predicted body weights revealed significant differences between undersized, matched, and oversized subsets (11.4 ± 3.1 vs 9.4 ± 1.2 vs 8.1 ± 2.1, respectively; P < 0.05). Two patients developed primary graft dysfunction grade 3, both in the undersized subset. Four patients in the undersized group underwent tracheotomy (vs none in matched and one in oversized subset). During mechanical ventilation after bilateral lung transplantation, undersized allografts received relatively higher tidal volumes compared with oversized allografts when the tidal volumes were related to donor-predicted body weights.

Halothane reduces the early lipopolysaccharide-induced lung inflammation in mechanically ventilated rats.

PubMed

Giraud, O; Seince, P F; Rolland, C; Leçon-Malas, V; Desmonts, J M; Aubier, M; Dehoux, M

2000-12-01

Several studies suggest that anesthetics modulate the immune response. The aim of this study was to investigate the effect of halothane and thiopental on the lung inflammatory response. Rats submitted or not to intratracheal (IT) instillation of lipopolysaccharides (LPS) were anesthetized with either halothane (0. 5, 1, or 1.5%) or thiopental (60 mg. kg(-1)) and mechanically ventilated for 4 h. Control rats were treated or not by LPS without anesthesia. Lung inflammation was assessed by total and differential cell counts in bronchoalveolar lavage fluids (BALF) and by cytokine measurements (tumor necrosis factor-alpha [TNF-alpha], interleukin-6 [IL-6], macrophage inflammatory protein-2 [MIP-2], and monocyte chemoattractant protein-1 [MCP-1]) in BALF and lung homogenates. In the absence of LPS treatment, neither halothane nor thiopental modified the moderate inflammatory response induced by tracheotomy or mechanical ventilation. Cell recruitment and cytokine concentrations were increased in all groups receiving IT LPS. However, in halothane-anesthetized rats (halothane > or = 1%), but not in thiopental-anesthetized rats, the LPS-induced lung inflammation was altered in a dose-dependent manner. Indeed, when using 1% halothane, polymorphonuclear leukocyte (PMN) recruitment was decreased by 55% (p < 0.001) and TNF-alpha, IL-6, and MIP-2 concentrations in BALF and lung homogenates were decreased by more than 60% (p < 0.001) whereas total protein and MCP-1 concentrations remained unchanged. The decrease of MIP-2 (observed at the protein and messenger RNA [mRNA] level) was strongly correlated to the decrease of PMN recruitment (r = 0.73, p < 0.05). This halothane-reduced lung inflammatory response was transient and was reversed 20 h after the end of the anesthesia. Our study shows that halothane > or = 1%, delivered during 4 h by mechanical ventilation, but not mechanical ventilation per se, alters the early LPS-induced lung inflammation in the rat, suggesting a specific effect of halothane on this response.

A General Approach to the Evaluation of Ventilation-Perfusion Ratios in Normal and Abnormal Lungs

ERIC Educational Resources Information Center

Wagner, Peter D.

1977-01-01

Outlines methods for manipulating multiple gas data so as to gain the greatest amount of insight into the properties of ventilation-perfusion distributions. Refers to data corresponding to normal and abnormal lungs. Uses a two-dimensional framework with the respiratory gases of oxygen and carbon dioxide. (CS)

Hypercapnic acidosis modulates inflammation, lung mechanics, and edema in the isolated perfused lung.

PubMed

De Smet, Hilde R; Bersten, Andrew D; Barr, Heather A; Doyle, Ian R

2007-12-01

Low tidal volume (V(T)) ventilation strategies may be associated with permissive hypercapnia, which has been shown by ex vivo and in vivo studies to have protective effects. We hypothesized that hypercapnic acidosis may be synergistic with low V(T) ventilation; therefore, we studied the effects of hypercapnia and V(T) on unstimulated and lipopolysaccharide-stimulated isolated perfused lungs. Isolated perfused rat lungs were ventilated for 2 hours with low (7 mL/kg) or moderately high (20 mL/kg) V(T) and 5% or 20% CO(2), with lipopolysaccharide or saline added to the perfusate. Hypercapnia resulted in reduced pulmonary edema, lung stiffness, tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) in the lavage and perfusate. The moderately high V(T) did not cause lung injury but increased lavage IL-6 and perfusate IL-6 as well as TNF-alpha. Pulmonary edema and respiratory mechanics improved, possibly as a result of a stretch-induced increase in surfactant turnover. Lipopolysaccharide did not induce significant lung injury. We conclude that hypercapnia exerts a protective effect by modulating inflammation, lung mechanics, and edema. The moderately high V(T) used in this study stimulated inflammation but paradoxically improved edema and lung mechanics with an associated increase in surfactant release.

Hypergravity Alters the Susceptibility of Cells to Anoxia-Reoxygenation Injury

NASA Technical Reports Server (NTRS)

McCloud, Henry; Pink, Yulondo; Harris-Hooker, Sandra A.; Melhado, Caroline D.; Sanford, Gary L.

1997-01-01

Gravity is a physical force, much like shear stress or mechanical stretch, and should affect organ and cellular function. Researchers have shown that gravity plays a role in ventilation and blood flow distribution, gas exchange, alveolar size and mechanical stresses within the lung. Short exposure to microgravity produced marked alterations in lung blood flow and ventilation distribution while hypergravity exaggerated the regional differences in lung structure and function resulting in reduced ventilation at the base and no ventilation of the upper half of the lung. Microgravity also decreased metabolic activity in cardiac cells, WI-38 embryonic lung cells, and human lymphocytes. Rats, in the tail-suspended head-down tilt model, experienced transient loss of lung water, contrary to an expected increase due to pooling of blood in the pulmonary vasculature. Hypergravity has also been found to increase the proliferation of several different cell lines (e.g., chick embryo fibroblasts) while decreasing cell motility and slowing liver regeneration following partial hepatectomy. These studies show that changes in the gravity environment will affect several aspects of organ and cellular function and produce major change in blood flow and tissue/organ perfusion. However, these past studies have not addressed whether ischemia-reperfusion injury will be exacerbated or ameliorated by changes in the gravity environment, e.g., space flight. Currently, nothing is known about how gravity will affect the susceptibility of different lung and vascular cells to this type of injury. We conducted studies that addressed the following question: Does the susceptibility of lung fibroblasts, vascular smooth muscle, and endothelial cells to anoxia/reoxygenation injury change following exposure to hypergravity conditions?

21 CFR 868.5935 - External negative pressure ventilator.

Code of Federal Regulations, 2010 CFR

2010-04-01

... ventilator. (a) Identification. An external negative pressure ventilator (e.g., iron lung, cuirass) is a device chamber that is intended to support a patient's ventilation by alternately applying and releasing external negative pressure over the diaphragm and upper trunk of the patient. (b) Classification. Class II...

Pulmonary lesion induced by low and high positive end-expiratory pressure levels during protective ventilation in experimental acute lung injury.

PubMed

Pássaro, Caroline P; Silva, Pedro L; Rzezinski, Andréia F; Abrantes, Simone; Santiago, Viviane R; Nardelli, Liliane; Santos, Raquel S; Barbosa, Carolina M L; Morales, Marcelo M; Zin, Walter A; Amato, Marcelo B P; Capelozzi, Vera L; Pelosi, Paolo; Rocco, Patricia R M

2009-03-01

To investigate the effects of low and high levels of positive end-expiratory pressure (PEEP), without recruitment maneuvers, during lung protective ventilation in an experimental model of acute lung injury (ALI). Prospective, randomized, and controlled experimental study. University research laboratory. Wistar rats were randomly assigned to control (C) [saline (0.1 mL), intraperitoneally] and ALI [paraquat (15 mg/kg), intraperitoneally] groups. After 24 hours, each group was further randomized into four groups (six rats each) at different PEEP levels = 1.5, 3, 4.5, or 6 cm H2O and ventilated with a constant tidal volume (6 mL/kg) and open thorax. Lung mechanics [static elastance (Est, L) and viscoelastic pressure (DeltaP2, L)] and arterial blood gases were measured before (Pre) and at the end of 1-hour mechanical ventilation (Post). Pulmonary histology (light and electron microscopy) and type III procollagen (PCIII) messenger RNA (mRNA) expression were measured after 1 hour of mechanical ventilation. In ALI group, low and high PEEP levels induced a greater percentage of increase in Est, L (44% and 50%) and DeltaP2, L (56% and 36%) in Post values related to Pre. Low PEEP yielded alveolar collapse whereas high PEEP caused overdistension and atelectasis, with both levels worsening oxygenation and increasing PCIII mRNA expression. In the present nonrecruited ALI model, protective mechanical ventilation with lower and higher PEEP levels than required for better oxygenation increased Est, L and DeltaP2, L, the amount of atelectasis, and PCIII mRNA expression. PEEP selection titrated for a minimum elastance and maximum oxygenation may prevent lung injury while deviation from these settings may be harmful.

CPAP of 4 cm H(2)O Has no short-term benefit at term in infants with BPD.

PubMed

Sandberg, Kenneth L; Hjalmarson, Ola

2012-01-01

Lung development and function is compromised at term in infants with bronchopulmonary dysplasia (BPD), characterized by reduced functional residual capacity (FRC) and impaired gas-mixing efficiency in distal airways. To determine whether continuous positive airway pressure (CPAP) improves FRC, ventilation, distal airway function, and gas exchange in spontaneously breathing infants with BPD. Twenty-one infants with BPD (median birth weight 0.72 kg (range 0.50-1.27) and median gestational age 26 weeks (range 23-28)) were studied before and after CPAP of 4 cm H(2)O was applied by a facemask system. A multiple-breath nitrogen washout method was used to assess FRC, ventilation, and gas-mixing efficiency. Moment analysis and lung clearance index was calculated from the nitrogen-decay curve for assessment of gas-mixing efficiency. Transcutaneous (Tc) PO(2)/PCO(2) was monitored during stable infant conditions before each washout test. When CPAP was raised from 0 to 4 cm H(2)O, FRC increased significantly together with a significant increase in moment ratios (M(1)/M(0) and M(2)/M(0)). Tc PO(2) decreased significantly and the breathing pattern changed, with significantly reduced respiratory rate, minute ventilation, and alveolar ventilation. There was also an increase in tidal volume and dead space. CPAP of 4 cm H(2)O applied with a facemask at term to infants with BPD did not improve ventilation, gas-mixing efficiency in distal airways, or oxygenation despite an increase in FRC. We speculate that instead of promoting recruitment of unventilated lung volumes, increasing the end-expiratory pressure in infants with BPD may lead to an overexpansion of already ventilated parts of the lung, causing further compromise of lung function. Copyright © 2012 S. Karger AG, Basel.

Feasibility of quantitative regional ventilation and perfusion mapping with phase-resolved functional lung (PREFUL) MRI in healthy volunteers and COPD, CTEPH, and CF patients.

PubMed

Voskrebenzev, Andreas; Gutberlet, Marcel; Klimeš, Filip; Kaireit, Till F; Schönfeld, Christian; Rotärmel, Alexander; Wacker, Frank; Vogel-Claussen, Jens

2018-04-01

In this feasibility study, a phase-resolved functional lung imaging postprocessing method for extraction of dynamic perfusion (Q) and ventilation (V) parameters using a conventional 1H lung MRI Fourier decomposition acquisition is introduced. Time series of coronal gradient-echo MR images with a temporal resolution of 288 to 324 ms of two healthy volunteers, one patient with chronic thromboembolic hypertension, one patient with cystic fibrosis, and one patient with chronic obstructive pulmonary disease were acquired at 1.5 T. Using a sine model to estimate cardiac and respiratory phases of each image, all images were sorted to reconstruct full cardiac and respiratory cycles. Time to peak (TTP), V/Q maps, and fractional ventilation flow-volume loops were calculated. For the volunteers, homogenous ventilation and perfusion TTP maps (V-TTP, Q-TTP) were obtained. The chronic thromboembolic hypertension patient showed increased perfusion TTP in hypoperfused regions in visual agreement with dynamic contrast-enhanced MRI, which improved postpulmonary endaterectomy surgery. Cystic fibrosis and chronic obstructive pulmonary disease patients showed a pattern of increased V-TTP and Q-TTP in regions of hypoventilation and decreased perfusion. Fractional ventilation flow-volume loops of the chronic obstructive pulmonary disease patient were smaller in comparison with the healthy volunteer, and showed regional differences in visual agreement with functional small airways disease and emphysema on CT. This study shows the feasibility of phase-resolved functional lung imaging to gain quantitative information regarding regional lung perfusion and ventilation without the need for ultrafast imaging, which will be advantageous for future clinical translation. Magn Reson Med 79:2306-2314, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Respiratory Management of Perioperative Obese Patients.

PubMed

Imber, David Ae; Pirrone, Massimiliano; Zhang, Changsheng; Fisher, Daniel F; Kacmarek, Robert M; Berra, Lorenzo

2016-12-01

With a rising incidence of obesity in the United States, anesthesiologists are faced with a larger volume of obese patients coming to the operating room as well as obese patients with ever-larger body mass indices (BMIs). While there are many cardiovascular and endocrine issues that clinicians must take into account when caring for the obese patient, one of the most prominent concerns of the anesthesiologist in the perioperative setting should be the status of the lung. Because the pathophysiology of reduced lung volumes in the obese patient differs from that of the ARDS patient, the best approach to keeping the obese patient's lung open and adequately ventilated during mechanical ventilation is unique. Although strong evidence and research are lacking regarding how to best ventilate the obese surgical patient, we aim with this review to provide an assessment of the small amount of research that has been conducted and the pathophysiology we believe influences the apparent results. We will provide a basic overview of the anatomy and pathophysiology of the obese respiratory system and review studies concerning pre-, intra-, and postoperative respiratory care. Our focus in this review centers on the best approach to keeping the lung recruited through the prevention of compression atelectasis and the maintaining of physiological lung volumes. We recommend the use of PEEP via noninvasive ventilation (NIV) before induction and endotracheal intubation, the use of both PEEP and periodic recruitment maneuvers during mechanical ventilation, and the use of PEEP via NIV after extubation. It is our hope that by studying the underlying mechanisms that make ventilating obese patients so difficult, future research can be better tailored to address this increasingly important challenge to the field of anesthesia. Copyright © 2016 by Daedalus Enterprises.

Neurally adjusted ventilatory assist in patients with acute respiratory failure: study protocol for a randomized controlled trial.

PubMed

Villar, Jesús; Belda, Javier; Blanco, Jesús; Suarez-Sipmann, Fernando; Añón, José Manuel; Pérez-Méndez, Lina; Ferrando, Carlos; Parrilla, Dácil; Montiel, Raquel; Corpas, Ruth; González-Higueras, Elena; Pestaña, David; Martínez, Domingo; Fernández, Lorena; Soro, Marina; García-Bello, Miguel Angel; Fernández, Rosa Lidia; Kacmarek, Robert M

2016-10-13

Patient-ventilator asynchrony is a common problem in mechanically ventilated patients with acute respiratory failure. It is assumed that asynchronies worsen lung function and prolong the duration of mechanical ventilation (MV). Neurally Adjusted Ventilatory Assist (NAVA) is a novel approach to MV based on neural respiratory center output that is able to trigger, cycle, and regulate the ventilatory cycle. We hypothesized that the use of NAVA compared to conventional lung-protective MV will result in a reduction of the duration of MV. It is further hypothesized that NAVA compared to conventional lung-protective MV will result in a decrease in the length of ICU and hospital stay, and mortality. This is a prospective, multicenter, randomized controlled trial in 306 mechanically ventilated patients with acute respiratory failure from several etiologies. Only patients ventilated for less than 5 days, and who are expected to require prolonged MV for an additional 72 h or more and are able to breathe spontaneously, will be considered for enrollment. Eligible patients will be randomly allocated to two ventilatory arms: (1) conventional lung-protective MV (n = 153) and conventional lung-protective MV with NAVA (n = 153). Primary outcome is the number of ventilator-free days, defined as days alive and free from MV at day 28 after endotracheal intubation. Secondary outcomes are total length of MV, and ICU and hospital mortality. This is the first randomized clinical trial examining, on a multicenter scale, the beneficial effects of NAVA in reducing the dependency on MV of patients with acute respiratory failure. ClinicalTrials.gov website ( NCT01730794 ). Registered on 15 November 2012.

Ventilation distribution measured with EIT at varying levels of pressure support and Neurally Adjusted Ventilatory Assist in patients with ALI.

PubMed

Blankman, Paul; Hasan, Djo; van Mourik, Martijn S; Gommers, Diederik

2013-06-01

The purpose of this study was to compare the effect of varying levels of assist during pressure support (PSV) and Neurally Adjusted Ventilatory Assist (NAVA) on the aeration of the dependent and non-dependent lung regions by means of Electrical Impedance Tomography (EIT). We studied ten mechanically ventilated patients with Acute Lung Injury (ALI). Positive-End Expiratory Pressure (PEEP) and PSV levels were both 10 cm H₂O during the initial PSV step. Thereafter, we changed the inspiratory pressure to 15 and 5 cm H₂O during PSV. The electrical activity of the diaphragm (EAdi) during pressure support ten was used to define the initial NAVA gain (100 %). Thereafter, we changed NAVA gain to 150 and 50 %, respectively. After each step the assist level was switched back to PSV 10 cm H₂O or NAVA 100 % to get a new baseline. The EIT registration was performed continuously. Tidal impedance variation significantly decreased during descending PSV levels within patients, whereas not during NAVA. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, was lower during PSV compared to NAVA. Ventilation contribution of the dependent lung region was equally in balance with the non-dependent lung region during PSV 5 cm H₂O, NAVA 50 and 100 %. Neurally Adjusted Ventilatory Assist ventilation had a beneficial effect on the ventilation of the dependent lung region and showed less over-assistance compared to PSV in patients with ALI.

Control of respiration in fish, amphibians and reptiles.

PubMed

Taylor, E W; Leite, C A C; McKenzie, D J; Wang, T

2010-05-01

Fish and amphibians utilise a suction/force pump to ventilate gills or lungs, with the respiratory muscles innervated by cranial nerves, while reptiles have a thoracic, aspiratory pump innervated by spinal nerves. However, fish can recruit a hypobranchial pump for active jaw occlusion during hypoxia, using feeding muscles innervated by anterior spinal nerves. This same pump is used to ventilate the air-breathing organ in air-breathing fishes. Some reptiles retain a buccal force pump for use during hypoxia or exercise. All vertebrates have respiratory rhythm generators (RRG) located in the brainstem. In cyclostomes and possibly jawed fishes, this may comprise elements of the trigeminal nucleus, though in the latter group RRG neurons have been located in the reticular formation. In air-breathing fishes and amphibians, there may be separate RRG for gill and lung ventilation. There is some evidence for multiple RRG in reptiles. Both amphibians and reptiles show episodic breathing patterns that may be centrally generated, though they do respond to changes in oxygen supply. Fish and larval amphibians have chemoreceptors sensitive to oxygen partial pressure located on the gills. Hypoxia induces increased ventilation and a reflex bradycardia and may trigger aquatic surface respiration or air-breathing, though these latter activities also respond to behavioural cues. Adult amphibians and reptiles have peripheral chemoreceptors located on the carotid arteries and central chemoreceptors sensitive to blood carbon dioxide levels. Lung perfusion may be regulated by cardiac shunting and lung ventilation stimulates lung stretch receptors.

Prophylactic Use of High-Frequency Percussive Ventilation in Patients with Inhalation Injury,

DTIC Science & Technology

1991-06-01

stabilizing such col- in burn wound management, infection control, lapsed diseased lung segments. 3- 2 In addition some in- and metabolic support increased the...confirmed in each patient by bronchoscopy and/or󈧥 Xe- 8. PCO2 < 50 mmHg but progressively increasing non ventilation-perfusion lung scan. The presence of...death for all patients admitted to the In- Inhalation injury documented by bronchoscopy or Xenon lung scan stitute of Surgical Research between January

Lung recruitment manoeuvres are effective in regaining lung volume and oxygenation after open endotracheal suctioning in acute respiratory distress syndrome

PubMed Central

Dyhr, Thomas; Bonde, Jan; Larsson, Anders

2003-01-01

Introduction Lung collapse is a contributory factor in the hypoxaemia that is observed after open endotracheal suctioning (ETS) in patients with acute lung injury and acute respiratory distress syndrome. Lung recruitment (LR) manoeuvres may be effective in rapidly regaining lung volume and improving oxygenation after ETS. Materials and method A prospective, randomized, controlled study was conducted in a 15-bed general intensive care unit at a university hospital. Eight consecutive mechanically ventilated patients with acute lung injury or acute respiratory distress syndrome were included. One of two suctioning procedures was performed in each patient. In the first procedure, ETS was performed followed by LR manoeuvre and reconnection to the ventilator with positive end-expiratory pressure set at 1 cmH2O above the lower inflexion point, and after 60 min another ETS (but without LR manoeuvre) was performed followed by reconnection to the ventilator with similar positive end-expiratory pressure; the second procedure was the same as the first but conducted in reverse order. Before (baseline) and over 25 min following each ETS procedure, partial arterial oxygen tension (PaO2) and end-expiratory lung volume were measured. Results After ETS, PaO2 decreased by 4.3(0.9–9.7)kPa (median and range; P < 0.005). After LR manoeuvre, PaO2 recovered to baseline. Without LR manoeuvre, PaO2 was reduced (P = 0.05) until 7 min after ETS. With LR manoeuvre end-expiratory lung volume was unchanged after ETS, whereas without LR manoeuvre end-expiratory lung volume was still reduced (approximately 10%) at 5 and 15 min after ETS (P = 0.01). Discussion A LR manoeuvre immediately following ETS was, as an adjunct to positive end-expiratory pressure, effective in rapidly counteracting the deterioration in PaO2 and lung volume caused by open ETS in ventilator-treated patients with acute lung injury or acute respiratory distress syndrome. PMID:12617741

Spontaneous Effort During Mechanical Ventilation: Maximal Injury With Less Positive End-Expiratory Pressure.

PubMed

Yoshida, Takeshi; Roldan, Rollin; Beraldo, Marcelo A; Torsani, Vinicius; Gomes, Susimeire; De Santis, Roberta R; Costa, Eduardo L V; Tucci, Mauro R; Lima, Raul G; Kavanagh, Brian P; Amato, Marcelo B P

2016-08-01

We recently described how spontaneous effort during mechanical ventilation can cause "pendelluft," that is, displacement of gas from nondependent (more recruited) lung to dependent (less recruited) lung during early inspiration. Such transfer depends on the coexistence of more recruited (source) liquid-like lung regions together with less recruited (target) solid-like lung regions. Pendelluft may improve gas exchange, but because of tidal recruitment, it may also contribute to injury. We hypothesize that higher positive end-expiratory pressure levels decrease the propensity to pendelluft and that with lower positive end-expiratory pressure levels, pendelluft is associated with improved gas exchange but increased tidal recruitment. Crossover design. University animal research laboratory. Anesthetized landrace pigs. Surfactant depletion was achieved by saline lavage in anesthetized pigs, and ventilator-induced lung injury was produced by ventilation with high tidal volume and low positive end-expiratory pressure. Ventilation was continued in each of four conditions: positive end-expiratory pressure (low or optimized positive end-expiratory pressure after recruitment) and spontaneous breathing (present or absent). Tidal recruitment was assessed using dynamic CT and regional ventilation/perfusion using electric impedance tomography. Esophageal pressure was measured using an esophageal balloon manometer. Among the four conditions, spontaneous breathing at low positive end-expiratory pressure not only caused the largest degree of pendelluft, which was associated with improved ventilation/perfusion matching and oxygenation, but also generated the greatest tidal recruitment. At low positive end-expiratory pressure, paralysis worsened oxygenation but reduced tidal recruitment. Optimized positive end-expiratory pressure decreased the magnitude of spontaneous efforts (measured by esophageal pressure) despite using less sedation, from -5.6 ± 1.3 to -2.0 ± 0.7 cm H2O, while concomitantly reducing pendelluft and tidal recruitment. No pendelluft was observed in the absence of spontaneous effort. Spontaneous effort at low positive end-expiratory pressure improved oxygenation but promoted tidal recruitment associated with pendelluft. Optimized positive end-expiratory pressure (set after lung recruitment) may reverse the harmful effects of spontaneous breathing by reducing inspiratory effort, pendelluft, and tidal recruitment.

Pressure-limited sustained inflation vs. gradual tidal inflations for resuscitation in preterm lambs.

PubMed

Tingay, David G; Polglase, Graeme R; Bhatia, Risha; Berry, Clare A; Kopotic, Robert J; Kopotic, Clinton P; Song, Yong; Szyld, Edgardo; Jobe, Alan H; Pillow, J Jane

2015-04-01

Support of the mechanically complex preterm lung needs to facilitate aeration while avoiding ventilation heterogeneities: whether to achieve this gradually or quickly remains unclear. We compared the effect of gradual vs. constant tidal inflations and a pressure-limited sustained inflation (SI) at birth on gas exchange, lung mechanics, gravity-dependent lung volume distribution, and lung injury in 131-day gestation preterm lambs. Lambs were resuscitated with either 1) a 20-s, 40-cmH2O pressure-limited SI (PressSI), 2) a gradual increase in tidal volume (Vt) over 5-min from 3 ml/kg to 7 ml/kg (IncrVt), or 3) 7 ml/kg Vt from birth. All lambs were subsequently ventilated for 15 min with 7 ml/kg Vt with the same end-expiratory pressure. Lung mechanics, gas exchange and spatial distribution of end-expiratory volume (EEV), and tidal ventilation (electrical impedance tomography) were recorded regularly. At 15 min, early mRNA tissue markers of lung injury were assessed. The IncrVt group resulted in greater tissue hysteresivity at 5 min (P = 0.017; two-way ANOVA), higher alveolar-arterial oxygen difference from 10 min (P < 0.01), and least uniform gravity-dependent distribution of EEV. There were no other differences in lung mechanics between groups, and the PressSI and 7 ml/kg Vt groups behaved similarly throughout. EEV was more uniformly distributed, but Vt least so, in the PressSI group. There were no differences in mRNA markers of lung injury. A gradual increase in Vt from birth resulted in less recruitment of the gravity-dependent lung with worse oxygenation. There was no benefit of a SI at birth over mechanical ventilation with 7 ml/kg Vt. Copyright © 2015 the American Physiological Society.

Dosimetric feasibility of 4DCT-ventilation imaging guided proton therapy for locally advanced non-small-cell lung cancer.

PubMed

Huang, Qijie; Jabbour, Salma K; Xiao, Zhiyan; Yue, Ning; Wang, Xiao; Cao, Hongbin; Kuang, Yu; Zhang, Yin; Nie, Ke

2018-04-25

The principle aim of this study is to incorporate 4DCT ventilation imaging into functional treatment planning that preserves high-functioning lung with both double scattering and scanning beam techniques in proton therapy. Eight patients with locally advanced non-small-cell lung cancer were included in this study. Deformable image registration was performed for each patient on their planning 4DCTs and the resultant displacement vector field with Jacobian analysis was used to identify the high-, medium- and low-functional lung regions. Five plans were designed for each patient: a regular photon IMRT vs. anatomic proton plans without consideration of functional ventilation information using double scattering proton therapy (DSPT) and intensity modulated proton therapy (IMPT) vs. functional proton plans with avoidance of high-functional lung using both DSPT and IMPT. Dosimetric parameters were compared in terms of tumor coverage, plan heterogeneity, and avoidance of normal tissues. Our results showed that both DSPT and IMPT plans gave superior dose advantage to photon IMRTs in sparing low dose regions of the total lung in terms of V5 (volume receiving 5Gy). The functional DSPT only showed marginal benefit in sparing high-functioning lung in terms of V5 or V20 (volume receiving 20Gy) compared to anatomical plans. Yet, the functional planning in IMPT delivery, can further reduce the low dose in high-functioning lung without degrading the PTV dosimetric coverages, compared to anatomical proton planning. Although the doses to some critical organs might increase during functional planning, the necessary constraints were all met. Incorporating 4DCT ventilation imaging into functional proton therapy is feasible. The functional proton plans, in intensity modulated proton delivery, are effective to further preserve high-functioning lung regions without degrading the PTV coverage.

The risk of lung cancer among cooking adults: a meta-analysis of 23 observational studies.

PubMed

Jia, Peng-Li; Zhang, Chao; Yu, Jia-Jie; Xu, Chang; Tang, Li; Sun, Xin

2018-02-01

Cooking has been regarded as a potential risk factor for lung cancer. We aim to investigate the evidence of cooking oil fume and risk of lung cancer. Medline and Embase were searched for eligible studies. We conducted a meta-analysis to summarize the evidences of case-control or cohort studies, with subgroup analysis for the potential discrepancy. Sensitivity analysis was employed to test the robustness. We included 23 observational studies, involving 9411 lung cancer cases. Our meta-analysis found that, for cooking female, the pooled OR of cooking oil fume exposure was 1.98 (95% CI 1.54, 2.54, I 2  = 79%, n = 15) among non-smoking population and 2.00 (95% CI 1.46, 2.74, I 2  = 75%, n = 10) among partly smoking population. For cooking males, the pooled OR of lung cancer was 1.15 (95% CI 0.71, 1.87; I 2  = 80%, n = 4). When sub grouped by ventilation condition, the pooled OR for poor ventilation was 1.20 (95% CI 1.10, 1.31, I 2  = 2%) compared to good ventilation. For different cooking methods, our results suggested that stir frying (OR = 1.89, 95% CI 1.23, 2.90; I 2  = 66%) was associated with increased risk of lung cancer while not for deep frying (OR = 1.41, 95% CI 0.87, 2.29; I 2  = 5%). Sensitivity analysis suggested our results were stable. Cooking oil fume is likely to be a risk factor for lung cancer for female, regardless of smoking status. Poor ventilation may increase the risk of lung cancer. Cooking methods may have different effect on lung cancer that deep frying may be healthier than stir frying.

The effect of experience, simulator-training and biometric feedback on manual ventilation technique.

PubMed

Lewis, Rebecca; Sherfield, Cerrie A; Fellows, Christopher R; Burrow, Rachel; Young, Iain; Dugdale, Alex

2017-05-01

To determine the frequency of provision and main providers (veterinary surgeons, nurses or trainees) of manual ventilation in UK veterinary practices. Furthermore, to determine the variation in peak inspiratory (inflation) pressure (PIP), applied to a lung model during manual ventilation, by three different groups of operators (inexperienced, experienced and specialist), before and after training. Questionnaire survey, lung model simulator development and prospective testing. Postal questionnaires were sent to 100 randomly selected veterinary practices. The lung model simulator was manually ventilated in a staged process over 3 weeks, with and without real-time biometric feedback (PIP display), by three groups of volunteer operators: inexperienced, experienced and specialist. The questionnaires determined that veterinary nurses were responsible for providing the majority of manual ventilation in veterinary practices, mainly drawing on theoretical knowledge rather than any specific training. Thoracic surgery and apnoea were the main reasons for provision of manual ventilation. Specialists performed well when manually ventilating the lung model, regardless of feedback training. Both inexperienced and experienced operators showed significant improvement in technique when using the feedback training tool: variation in PIP decreased significantly until operators provided manual ventilation at PIPs within the defined optimum range. Preferences for different forms of feedback (graphical, numerical or scale display), revealed that the operators' choice was not always the method which gave least variation in PIP. This study highlighted a need for training in manual ventilation at an early stage in veterinary and veterinary nursing careers and demonstrated how feedback is important in the process of experiential learning. A manometer device which can provide immediate feedback during training, or indeed in a real clinical setting, should improve patient safety. Copyright © 2017 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.

Dynamic Determination of Oxygenation and Lung Compliance in Murine Pneumonectomy

PubMed Central

Gibney, Barry; Lee, Grace S.; Houdek, Jan; Lin, Miao; Miele, Lino; Chamoto, Kenji; Konerding, Moritz A.; Tsuda, Akira; Mentzer, Steven J.

2012-01-01

Thoracic surgical procedures in mice have been applied to a wide range of investigations, but little is known about the murine physiologic response to pulmonary surgery. Using continuous arterial oximetry monitoring and the FlexiVent murine ventilator, we investigated the effect of anesthesia and pneumonectomy on mouse oxygen saturation and lung mechanics. Sedation resulted in a dose-dependent decline of oxygen saturation that ranged from 55–82%. Oxygen saturation was restored by mechanical ventilation with increased rate and tidal volumes. In the mouse strain studied, optimal ventilatory rates were a rate of 200/minute and a tidal volume of 10ml/kg. Sustained inflation pressures, referred to as a "recruitment maneuver," improved lung volumes, lung compliance and arterial oxygenation. In contrast, positive end expiratory pressure (PEEP) had a detrimental effect on oxygenation; an effect that was ameliorated after pneumonectomy. Our results confirm that lung volumes in the mouse are dynamically determined and suggest a threshold level of mechanical ventilation to maintain perioperative oxygen saturation. PMID:21574875

Enhanced Photoacoustic Gas Analyser Response Time and Impact on Accuracy at Fast Ventilation Rates during Multiple Breath Washout

PubMed Central

Horsley, Alex; Macleod, Kenneth; Gupta, Ruchi; Goddard, Nick; Bell, Nicholas

2014-01-01

Background The Innocor device contains a highly sensitive photoacoustic gas analyser that has been used to perform multiple breath washout (MBW) measurements using very low concentrations of the tracer gas SF6. Use in smaller subjects has been restricted by the requirement for a gas analyser response time of <100 ms, in order to ensure accurate estimation of lung volumes at rapid ventilation rates. Methods A series of previously reported and novel enhancements were made to the gas analyser to produce a clinically practical system with a reduced response time. An enhanced lung model system, capable of delivering highly accurate ventilation rates and volumes, was used to assess in vitro accuracy of functional residual capacity (FRC) volume calculation and the effects of flow and gas signal alignment on this. Results 10–90% rise time was reduced from 154 to 88 ms. In an adult/child lung model, accuracy of volume calculation was −0.9 to 2.9% for all measurements, including those with ventilation rate of 30/min and FRC of 0.5 L; for the un-enhanced system, accuracy deteriorated at higher ventilation rates and smaller FRC. In a separate smaller lung model (ventilation rate 60/min, FRC 250 ml, tidal volume 100 ml), mean accuracy of FRC measurement for the enhanced system was minus 0.95% (range −3.8 to 2.0%). Error sensitivity to flow and gas signal alignment was increased by ventilation rate, smaller FRC and slower analyser response time. Conclusion The Innocor analyser can be enhanced to reliably generate highly accurate FRC measurements down at volumes as low as those simulating infant lung settings. Signal alignment is a critical factor. With these enhancements, the Innocor analyser exceeds key technical component recommendations for MBW apparatus. PMID:24892522

Effect of sustained inflation duration; resuscitation of near-term asphyxiated lambs.

PubMed

Klingenberg, Claus; Sobotka, Kristina S; Ong, Tracey; Allison, Beth J; Schmölzer, Georg M; Moss, Timothy J M; Polglase, Graeme R; Dawson, Jennifer A; Davis, Peter G; Hooper, Stuart B

2013-05-01

The 2010 ILCOR neonatal resuscitation guidelines do not specify appropriate inflation times for the initial lung inflations in apnoeic newborn infants. The authors compared three ventilation strategies immediately after delivery in asphyxiated newborn lambs. Experimental animal study. Facility for animal research. Eighteen near-term lambs (weight 3.5-3.9 kg) delivered by caesarean section. Asphyxia was induced by occluding the umbilical cord and delaying ventilation onset (10-11 min) until mean carotid blood pressure (CBP) was ≤22 mm Hg. Animals were divided into three groups (n=6) and ventilation started with: (1) inflation times of 0.5 s at a ventilation rate 60/min, (2) five 3 s inflations or (3) a single 30 s inflation. Subsequent ventilation used inflations at 0.5 s at 60/min for all groups. Times to reach a heart rate (HR) of 120 bpm and a mean CBP of 40 mm Hg. Secondary outcome was change in lung compliance. Median time to reach HR 120 bpm and mean CBP 40 mm Hg was significantly shorter in the single 30 s inflation group (8 s and 74 s) versus the 5×3 s inflation group (38 s and 466 s) and the conventional ventilation group (64 s and 264 s). Lung compliance was significantly better in the single 30 s inflation group. A single sustained inflation of 30 s immediately after birth improved speed of circulatory recovery and lung compliance in near-term asphyxiated lambs. This approach for neonatal resuscitation merits further investigation.

Effect of mechanical ventilation on regional variation of pleural liquid thickness in rabbits.

PubMed

Wang, P M; Lai-Fook, S J

1997-01-01

We studied the effect of ventilation on the regional distribution of pleural liquid thickness in anesthetized rabbits. Three transparent pleural windows were made between the second and eight intercostal space along the midaxillary line of the right chest. Fluorescein isothiocyanate-labeled dextran (1 ml) was injected into the pleural space through a rib capsule and allowed to mix with the pleural liquid. The light emitted from the pleural space beneath the windows was measured by fluorescence videomicroscopy at a constant tidal volume (20 ml) and two ventilation frequencies (20 and 40 breaths/min). Pleural liquid thickness was determined from the light measurements after in vitro calibration of pleural liquid collected postmortem. At 20 breaths/min, pleural liquid thickness increased with a cranial-caudal distance from 5 microns at the second to third intercostal space to 30 microns at the sixth through eighth intercostal space. At 40 breaths/min, pleural space thickness was unchanged at the second to third intercostal space but increased to 46 microns at the sixth through eighth intercostal space. To determine this effect on pleural liquid shear stress, we measured relative lung velocity from videomicroscopic images of the lung surface through the windows. Lung velocity amplitude increased with cranial-caudal distance and with ventilation frequency. Calculated shear stress amplitude was constant with cranial-caudal distance but increased with ventilation frequency. Thus, pleural liquid thickness is matched to the relative lung motion so as to maintain a spatially uniform shear stress amplitude in pleural liquid during mechanical ventilation.

Modeling of lung cancer risk due to radon exhalation of granite stone in dwelling houses.

PubMed

Abbasi, Akbar

2017-01-01

Due to increasing occurrences of lung cancer, radon exhalation rates, radon concentrations, and lung cancer risks in several types of commonly used granite stone, samples used for flooring in buildings, have been investigated. We measured the radon exhalation rates due to granite stones by means of an AlphaGUARD Model PQ2000 in a cube container with changeable floor by various granite stones. The lung cancer risk and percentage of lung cancer deaths (LCRn) due to those conditions were calculated using Darby's model. The radon exhalation rates ranged from 1.59 ± 0.41 to 9.43 ± 0.74 Bq/m 2/h. The radon concentrations in the standard room with poor and normal ventilation were calculated 20.10-71.09 Bq/m 3 and 16.12-47.01 Bq/m 3, respectively. The estimated numbers of lung cancer deaths attributable to indoor radon due to granite stones in 2013 were 145 (3.33%) and 103 (2.37%) for poor and normal ventilation systems, respectively. According to our estimations, the values of 3.33% and 2.37% of lung cancer deaths in 2013 are attributed to radon exhalation of granite stones with poor and normal ventilation systems, respectively.

Brain-lung crosstalk in critical care: how protective mechanical ventilation can affect the brain homeostasis.

PubMed

Mazzeo, A T; Fanelli, V; Mascia, L

2013-03-01

The maintenance of brain homeostasis against multiple internal and external challenges occurring during the acute phase of acute brain injury may be influenced by critical care management, especially in its respiratory, hemodynamic and metabolic components. The occurrence of acute lung injury represents the most frequent extracranial complication after brain injury and deserves special attention in daily practice as optimal ventilatory strategy for patients with acute brain and lung injury are potentially in conflict. Protecting the lung while protecting the brain is thus a new target in the modern neurointensive care. This article discusses the essentials of brain-lung crosstalk and focuses on how mechanical ventilation may exert an active role in the process of maintaining or treatening brain homeostasis after acute brain injury, highlighting the following points: 1) the role of inflammation as common pathomechanism of both acute lung and brain injury; 2) the recognition of ventilatory induced lung injury as determinant of systemic inflammation affecting distal organs, included the brain; 3) the possible implication of protective mechanical ventilation strategy on the patient with an acute brain injury as an undiscovered area of research in both experimental and clinical settings.

Continuous Negative Abdominal Pressure Reduces Ventilator-induced Lung Injury in a Porcine Model.

PubMed

Yoshida, Takeshi; Engelberts, Doreen; Otulakowski, Gail; Katira, Bhushan; Post, Martin; Ferguson, Niall D; Brochard, Laurent; Amato, Marcelo B P; Kavanagh, Brian P

2018-04-27

In supine patients with acute respiratory distress syndrome, the lung typically partitions into regions of dorsal atelectasis and ventral aeration ("baby lung"). Positive airway pressure is often used to recruit atelectasis, but often overinflates ventral (already aerated) regions. A novel approach to selective recruitment of dorsal atelectasis is by "continuous negative abdominal pressure." A randomized laboratory study was performed in anesthetized pigs. Lung injury was induced by surfactant lavage followed by 1 h of injurious mechanical ventilation. Randomization (five pigs in each group) was to positive end-expiratory pressure (PEEP) alone or PEEP with continuous negative abdominal pressure (-5 cm H2O via a plexiglass chamber enclosing hindlimbs, pelvis, and abdomen), followed by 4 h of injurious ventilation (high tidal volume, 20 ml/kg; low expiratory transpulmonary pressure, -3 cm H2O). The level of PEEP at the start was ≈7 (vs. ≈3) cm H2O in the PEEP (vs. PEEP plus continuous negative abdominal pressure) groups. Esophageal pressure, hemodynamics, and electrical impedance tomography were recorded, and injury determined by lung wet/dry weight ratio and interleukin-6 expression. All animals survived, but cardiac output was decreased in the PEEP group. Addition of continuous negative abdominal pressure to PEEP resulted in greater oxygenation (PaO2/fractional inspired oxygen 316 ± 134 vs. 80 ± 24 mmHg at 4 h, P = 0.005), compliance (14.2 ± 3.0 vs. 10.3 ± 2.2 ml/cm H2O, P = 0.049), and homogeneity of ventilation, with less pulmonary edema (≈10% less) and interleukin-6 expression (≈30% less). Continuous negative abdominal pressure added to PEEP reduces ventilator-induced lung injury in a pig model compared with PEEP alone, despite targeting identical expiratory transpulmonary pressure.

Progressive ventilation inhomogeneity in infants with cystic fibrosis after pulmonary infection.

PubMed

Simpson, Shannon J; Ranganathan, Sarath; Park, Judy; Turkovic, Lidija; Robins-Browne, Roy M; Skoric, Billy; Ramsey, Kathryn A; Rosenow, Tim; Banton, Georgia L; Berry, Luke; Stick, Stephen M; Hall, Graham L

2015-12-01

Measures of ventilation distribution are promising for monitoring early lung disease in cystic fibrosis (CF). This study describes the cross-sectional and longitudinal impacts of pulmonary inflammation and infection on ventilation homogeneity in infants with CF.Infants diagnosed with CF underwent multiple breath washout (MBW) testing and bronchoalveolar lavage at three time points during the first 2 years of life.Measures were obtained for 108 infants on 156 occasions. Infants with a significant pulmonary infection at the time of MBW showed increases in lung clearance index (LCI) of 0.400 units (95% CI 0.150-0.648; p=0.002). The impact was long lasting, with previous pulmonary infection leading to increased ventilation inhomogeneity over time compared to those who remained free of infection (p<0.05). Infection with Haemophilus influenzae was particularly detrimental to the longitudinal lung function in young children with CF where LCI was increased by 1.069 units for each year of life (95% CI 0.484-1.612; p<0.001).Pulmonary infection during the first year of life is detrimental to later lung function. Therefore, strategies aimed at prevention, surveillance and eradication of pulmonary pathogens are paramount to preserve lung function in infants with CF. Copyright ©ERS 2015.

Electrical impedance tomography.

PubMed

Costa, Eduardo L V; Lima, Raul Gonzalez; Amato, Marcelo B P

2009-02-01

Electrical impedance tomography (EIT) is a noninvasive, radiation-free monitoring tool that allows real-time imaging of ventilation. The purpose of this article is to discuss the fundamentals of EIT and to review the use of EIT in critical care patients. In addition to its established role in describing the distribution of alveolar ventilation, EIT has been shown to be a useful tool to detect lung collapse and monitor lung recruitment, both regionally and on a global basis. EIT has also been used to diagnose with high sensitivity incident pneumothoraces during mechanical ventilation. Additionally, with injection of hypertonic saline as a contrast agent, it is possible to estimate ventilation/perfusion distributions. EIT is cheap, noninvasive and allows continuous monitoring of ventilation. It is gaining acceptance as a valuable monitoring tool for the care of critical patients.

Monitoring lung contusion in a porcine polytrauma model using EIT: an application study.

PubMed

Santos, Susana Aguiar; Wembers, Carlos Castelar; Horst, Klemens; Pfeifer, Roman; Simon, Tim-Philipp; Pape, Hans-Christoph; Hildebrand, Frank; Czaplik, Michael; Leonhardt, Steffen; Teichmann, Daniel

2017-07-26

Lung contusion is the most common lung injury following blunt chest trauma which, in turn, is associated with high mortality rates (Gavelli et al 2002 Eur. Radiol. 12 1273-94). Lung contusion is characterized by hemorrhage and edema with consecutively reduced compliance. Objective and Approach: In this study, unilateral lung contusion and other traumata were induced in 12 pigs by using a bolt gun machine. To investigate the pathophysiological consequences of lung contusion, information on clinical parameters was collected and monitored regularly while animals were additionally monitored with electrical impedance tomography (EIT) before trauma, and at 4, 24, 48 and 72 h after polytrauma. Statistical analyses showed significant differences between the measurement time points in terms of lung compliance ([Formula: see text]) and in global EIT parameters, such as absolute global impedance (aGlobImp) ([Formula: see text]), tidal impedance variation (TIV) ([Formula: see text]) and the center of ventilation (CoV) ([Formula: see text]). Additionally, distinct analyses for the left (non-injured) and right (injured) lung were also performed. In this context, during the progress of lung contusion, significant changes were found for the injured lung in TIV ([Formula: see text]), global inhomogeneity ([Formula: see text]), regional ventilation delay ([Formula: see text]), CoV ([Formula: see text]) and in regions of non-ventilation (rNoVent) ([Formula: see text]). Furthermore, TIV and rNoVent were capable to differentiate the injured and the contralateral healthy lung at 4 and 24 h after injury (TIV: [Formula: see text] and [Formula: see text]; rNoVent: [Formula: see text] and [Formula: see text]). TIV reached a sensitivity of 82% (specificity of 100%) at 4 h and sensitivity of 82% (specificity of 82%) at 24 h after injury, in detecting lung contusion specific consequences. The results indicate that EIT might be a valuable tool to detect and to monitor lung injuries including lung contusion. Most probably, EIT-derived indices could also be used to adapt ventilator settings to optimize individual lung protection.

Inhalation therapy in mechanical ventilation

PubMed Central

Maccari, Juçara Gasparetto; Teixeira, Cassiano; Gazzana, Marcelo Basso; Savi, Augusto; Dexheimer-Neto, Felippe Leopoldo; Knorst, Marli Maria

2015-01-01

Patients with obstructive lung disease often require ventilatory support via invasive or noninvasive mechanical ventilation, depending on the severity of the exacerbation. The use of inhaled bronchodilators can significantly reduce airway resistance, contributing to the improvement of respiratory mechanics and patient-ventilator synchrony. Although various studies have been published on this topic, little is known about the effectiveness of the bronchodilators routinely prescribed for patients on mechanical ventilation or about the deposition of those drugs throughout the lungs. The inhaled bronchodilators most commonly used in ICUs are beta adrenergic agonists and anticholinergics. Various factors might influence the effect of bronchodilators, including ventilation mode, position of the spacer in the circuit, tube size, formulation, drug dose, severity of the disease, and patient-ventilator synchrony. Knowledge of the pharmacological properties of bronchodilators and the appropriate techniques for their administration is fundamental to optimizing the treatment of these patients. PMID:26578139

Common-path Fourier domain optical coherence tomography of irradiated human skin and ventilated isolated rabbit lungs

NASA Astrophysics Data System (ADS)

Popp, A.; Wendel, M.; Knels, L.; Knuschke, P.; Mehner, M.; Koch, T.; Boller, D.; Koch, P.; Koch, E.

2005-08-01

A compact common path Fourier domain optical coherence tomography (FD-OCT) system based on a broadband superluminescence diode is used for biomedical imaging. The epidermal thickening of human skin after exposure to ultraviolet radiation is measured to proof the feasibility of FD-OCT for future substitution of invasive biopsies in a long term study on natural UV skin protection. The FD-OCT system is also used for imaging lung parenchyma. FD-OCT images of a formalin fixated lung show the same alveolar structure as scanning electron microscopy images. In the ventilated and blood-free perfused isolated rabbit lung FD-OCT is used for real-time cross-sectional image capture of alveolar mechanics throughout tidal ventilation. The alveolar mechanics changing from alternating recruitment-derecruitment at zero positive end-expiratory pressure (PEEP) to persistent recruitment after applying a PEEP of 5 cm H2O is observed in the OCT images.

Spontaneously regulated vs. controlled ventilation of acute lung injury/acute respiratory distress syndrome.

PubMed

Marini, John J

2011-02-01

To present an updated discussion of those aspects of controlled positive pressure breathing and retained spontaneous regulation of breathing that impact the management of patients whose tissue oxygenation is compromised by acute lung injury. The recent introduction of ventilation techniques geared toward integrating natural breathing rhythms into even the earliest phase of acute respiratory distress syndrome support (e.g., airway pressure release, proportional assist ventilation, and neurally adjusted ventilatory assist), has stimulated a burst of new investigations. Optimizing gas exchange, avoiding lung injury, and preserving respiratory muscle strength and endurance are vital therapeutic objectives for managing acute lung injury. Accordingly, comparing the physiology and consequences of breathing patterns that preserve and eliminate breathing effort has been a theme of persisting investigative interest throughout the several decades over which it has been possible to sustain cardiopulmonary life support outside the operating theater.

[Lung-brain interaction in the mechanically ventilated patient].

PubMed

López-Aguilar, J; Fernández-Gonzalo, M S; Turon, M; Quílez, M E; Gómez-Simón, V; Jódar, M M; Blanch, L

2013-10-01

Patients with acute lung injury or acute respiratory distress syndrome (ARDS) admitted to the ICU present neuropsychological alterations, which in most cases extend beyond the acute phase and have an important adverse effect upon quality of life. The aim of this review is to deepen in the analysis of the complex interaction between lung and brain in critically ill patients subjected to mechanical ventilation. This update first describes the neuropsychological alterations occurring both during the acute phase of ICU stay and at discharge, followed by an analysis of lung-brain interactions during mechanical ventilation, and finally explores the etiology and mechanisms leading to the neurological disorders observed in these patients. The management of critical patients requires an integral approach focused on minimizing the deleterious effects over the short, middle or long term. Copyright © 2012 Elsevier España, S.L. y SEMICYUC. All rights reserved.

Variable Ventilation Improved Respiratory System Mechanics and Ameliorated Pulmonary Damage in a Rat Model of Lung Ischemia-Reperfusion.

PubMed

Soluri-Martins, André; Moraes, Lillian; Santos, Raquel S; Santos, Cintia L; Huhle, Robert; Capelozzi, Vera L; Pelosi, Paolo; Silva, Pedro L; de Abreu, Marcelo Gama; Rocco, Patricia R M

2017-01-01

Lung ischemia-reperfusion injury remains a major complication after lung transplantation. Variable ventilation (VV) has been shown to improve respiratory function and reduce pulmonary histological damage compared to protective volume-controlled ventilation (VCV) in different models of lung injury induced by endotoxin, surfactant depletion by saline lavage, and hydrochloric acid. However, no study has compared the biological impact of VV vs. VCV in lung ischemia-reperfusion injury, which has a complex pathophysiology different from that of other experimental models. Thirty-six animals were randomly assigned to one of two groups: (1) ischemia-reperfusion (IR), in which the left pulmonary hilum was completely occluded and released after 30 min; and (2) Sham, in which animals underwent the same surgical manipulation but without hilar clamping. Immediately after surgery, the left (IR-injured) and right (contralateral) lungs from 6 animals per group were removed, and served as non-ventilated group (NV) for molecular biology analysis. IR and Sham groups were further randomized to one of two ventilation strategies: VCV ( n = 6/group) [tidal volume (V T ) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 2 cmH 2 O, fraction of inspired oxygen (FiO 2 ) = 0.4]; or VV, which was applied on a breath-to-breath basis as a sequence of randomly generated V T values ( n = 1200; mean V T = 6 mL/kg), with a 30% coefficient of variation. After 5 min of ventilation and at the end of a 2-h period (Final), respiratory system mechanics and arterial blood gases were measured. At Final, lungs were removed for histological and molecular biology analyses. Respiratory system elastance and alveolar collapse were lower in VCV than VV (mean ± SD, VCV 3.6 ± 1.3 cmH 2 0/ml and 2.0 ± 0.8 cmH 2 0/ml, p = 0.005; median [interquartile range], VCV 20.4% [7.9-33.1] and VV 5.4% [3.1-8.8], p = 0.04, respectively). In left lungs of IR animals, VCV increased the expression of interleukin-6 and intercellular adhesion molecule-1 compared to NV, with no significant differences between VV and NV. Compared to VCV, VV increased the expression of surfactant protein-D, suggesting protection from type II epithelial cell damage. In conclusion, in this experimental lung ischemia-reperfusion model, VV improved respiratory system elastance and reduced lung damage compared to VCV.

Variable Ventilation Improved Respiratory System Mechanics and Ameliorated Pulmonary Damage in a Rat Model of Lung Ischemia-Reperfusion

PubMed Central

Soluri-Martins, André; Moraes, Lillian; Santos, Raquel S.; Santos, Cintia L.; Huhle, Robert; Capelozzi, Vera L.; Pelosi, Paolo; Silva, Pedro L.; de Abreu, Marcelo Gama; Rocco, Patricia R. M.

2017-01-01

Lung ischemia-reperfusion injury remains a major complication after lung transplantation. Variable ventilation (VV) has been shown to improve respiratory function and reduce pulmonary histological damage compared to protective volume-controlled ventilation (VCV) in different models of lung injury induced by endotoxin, surfactant depletion by saline lavage, and hydrochloric acid. However, no study has compared the biological impact of VV vs. VCV in lung ischemia-reperfusion injury, which has a complex pathophysiology different from that of other experimental models. Thirty-six animals were randomly assigned to one of two groups: (1) ischemia-reperfusion (IR), in which the left pulmonary hilum was completely occluded and released after 30 min; and (2) Sham, in which animals underwent the same surgical manipulation but without hilar clamping. Immediately after surgery, the left (IR-injured) and right (contralateral) lungs from 6 animals per group were removed, and served as non-ventilated group (NV) for molecular biology analysis. IR and Sham groups were further randomized to one of two ventilation strategies: VCV (n = 6/group) [tidal volume (VT) = 6 mL/kg, positive end-expiratory pressure (PEEP) = 2 cmH2O, fraction of inspired oxygen (FiO2) = 0.4]; or VV, which was applied on a breath-to-breath basis as a sequence of randomly generated VT values (n = 1200; mean VT = 6 mL/kg), with a 30% coefficient of variation. After 5 min of ventilation and at the end of a 2-h period (Final), respiratory system mechanics and arterial blood gases were measured. At Final, lungs were removed for histological and molecular biology analyses. Respiratory system elastance and alveolar collapse were lower in VCV than VV (mean ± SD, VCV 3.6 ± 1.3 cmH20/ml and 2.0 ± 0.8 cmH20/ml, p = 0.005; median [interquartile range], VCV 20.4% [7.9–33.1] and VV 5.4% [3.1–8.8], p = 0.04, respectively). In left lungs of IR animals, VCV increased the expression of interleukin-6 and intercellular adhesion molecule-1 compared to NV, with no significant differences between VV and NV. Compared to VCV, VV increased the expression of surfactant protein-D, suggesting protection from type II epithelial cell damage. In conclusion, in this experimental lung ischemia-reperfusion model, VV improved respiratory system elastance and reduced lung damage compared to VCV. PMID:28512431

Comparison of quantitative regional ventilation-weighted fourier decomposition MRI with dynamic fluorinated gas washout MRI and lung function testing in COPD patients.

PubMed

Kaireit, Till F; Gutberlet, Marcel; Voskrebenzev, Andreas; Freise, Julia; Welte, Tobias; Hohlfeld, Jens M; Wacker, Frank; Vogel-Claussen, Jens

2018-06-01

Ventilation-weighted Fourier decomposition-MRI (FD-MRI) has matured as a reliable technique for quantitative measures of regional lung ventilation in recent years, but has yet not been validated in COPD patients. To compare regional fractional lung ventilation obtained by ventilation-weighted FD-MRI with dynamic fluorinated gas washout MRI ( 19 F-MRI) and lung function test parameters. Prospective study. Twenty-seven patients with chronic obstructive pulmonary disease (COPD, median age 61 [54-67] years) were included. For FD-MRI and for 19 F-MRI a spoiled gradient echo sequence was used at 1.5T. FD-MRI coronal slices were acquired in free breathing. Dynamic 19 F-MRI was performed after inhalation of 25-30 L of a mixture of 79% fluorinated gas (C 3 F 8 ) and 21% oxygen via a closed face mask tubing using a dedicated coil tuned to 59.9 MHz. 19 F washout times in numbers of breaths ( 19 F-n breaths ) as well as fractional ventilation maps for both methods (FD-FV, 19 F-FV) were calculated. Slices were matched using a landmark driven algorithm, and only corresponding slices with an overlap of >90% were coregistered for evaluation. The obtained parameters were correlated with each other using Spearman's correlation coefficient (r). FD-FV strongly correlated with 19 F-n breaths on a global (r = -0.72, P < 0.0001) as well as on a lobar level and with lung function test parameters (FD-FV vs. FEV1, r = 0.76, P < 0.0001). There was a small systematic overestimation of FD-FV compared to 19 F-FV (mean difference -0.03 (95% confidence interval [CI]: -0.097; -0.045). Regional ventilation-weighted Fourier decomposition-MRI is a promising noninvasive, radiation-free tool for quantification of regional ventilation in COPD patients. 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018;47:1534-1541. © 2017 International Society for Magnetic Resonance in Medicine.

WE-AB-202-05: Validation of Lung Stress Maps for CT-Ventilation Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cazoulat, G; Jolly, S; Matuszak, M

Purpose: To date, lung CT-ventilation imaging has been based on quantification of local breathing-induced changes in Hounsfield Units (HU) or volume. This work investigates the use of a stress map resulting from a biomechanical deformable image registration (DIR) algorithm as a metric of the ventilation function. Method: Eight lung cancer patients presenting different kinds of ventilation defects were retrospectively analyzed. Additionally, to the 4DCT acquired for radiotherapy planning, five of them had PET and three had SPECT imaging following inhalation of Ga-68 and Tc-99m, respectively. For each patient, the inhale phase of the 4DCT was registered to the exhale phasemore » using Morfeus, a biomechanical DIR algorithm based on the determination of boundary conditions on the lung surfaces and vessel tree. To take into account the heterogeneity of the tissue stiffness in the stress map estimation, each tetrahedral element of the finite-element model was assigned a Young’s modulus ranging from 60kPa to 12MPa, as a function of the HU in the inhale CT. The node displacements and element stresses resulting from the numerical simulation were used to generate three CT-ventilation maps based on: (i) volume changes (Jacobian determinant), (ii) changes in HU, (iii) the maximum principal stress. The voxel-wise correlation between each CT-ventilation map and the PET or SPECT V image was computed in a lung mask. Results: For patients with PET, the mean (min-max) Spearman correlation coefficients r were: 0.33 (0.19–0.45), 0.36 (0.16–0.51) and 0.42 (0.21–0.59) considering the Jacobian, changes in HU and maximum principal stress, respectively. For patients with SPECT V, the mean r were: 0.12 (−0.12–0.43), 0.29 (0.22–0.45) and 0.33 (0.25–0.39). Conclusion: The maximum principal stress maps showed a stronger correlation with the ventilation images than the previously proposed Jacobian or change in HU maps. This metric thus appears promising for CT-ventilation imaging. This work was funded in part by NIH P01CA059827.« less

Basic principles of respiratory function monitoring in ventilated newborns: A review.

PubMed

Schmalisch, Gerd

2016-09-01

Respiratory monitoring during mechanical ventilation provides a real-time picture of patient-ventilator interaction and is a prerequisite for lung-protective ventilation. Nowadays, measurements of airflow, tidal volume and applied pressures are standard in neonatal ventilators. The measurement of lung volume during mechanical ventilation by tracer gas washout techniques is still under development. The clinical use of capnography, although well established in adults, has not been embraced by neonatologists because of technical and methodological problems in very small infants. While the ventilatory parameters are well defined, the calculation of other physiological parameters are based upon specific assumptions which are difficult to verify. Incomplete knowledge of the theoretical background of these calculations and their limitations can lead to incorrect interpretations with clinical consequences. Therefore, the aim of this review was to describe the basic principles and the underlying assumptions of currently used methods for respiratory function monitoring in ventilated newborns and to highlight methodological limitations. Copyright © 2016 Elsevier Ltd. All rights reserved.

A bench evaluation of fraction of oxygen in air delivery and tidal volume accuracy in home care ventilators available for hospital use

PubMed Central

Baboi, Loredana; Subtil, Fabien

2016-01-01

Background Turbine-powered ventilators are not only designed for long-term ventilation at home but also for hospital use. It is important to verify their capabilities in delivering fraction of oxygen in air (FIO2) and tidal volume (VT). Methods We assessed the FIO2 accuracy and the VT delivery in four home care ventilators (HCV) on the bench. The four HCV were Astral 150, Elisée 150, Monnal T50 and Trilogy 200 HCV, which were connected to a lung model (ASL 5000). For assessing FIO2 accuracy, lung model was set to mimic an obstructive lung and HCV were set in volume controlled mode (VC). They supplied with air, 3 or 15 L/min oxygen and FIO2 was measured by using a ventilator tester (Citrex H4TM). For the VT accuracy, the lung model was set in a way to mimic three adult configurations (normal, obstructive, or restrictive respiratory disorder) and one pediatric configuration. Each HCV was set in VC. Two VT (300 and 500 mL) in adult lung configuration and one 50 mL VT in pediatric lung configuration, at two positive end expiratory pressures 5 and 10 cmH2O, were tested. VT accuracy was measured as volume error (the relative difference between set and measured VT). Statistical analysis was performed by suing one-factor ANOVA with a Bonferroni correction for multiple tests. Results For Astral 150, Elisée 150, Monnal T50 and Trilogy 200, FIO2 averaged 99.2%, 93.7%, 86.3%, and 62.1%, respectively, at 15 L/min oxygen supplementation rate (P<0.001). Volume error was 0.5%±0%, −38%±0%, −9%±0%, −29%±0% and −36%±0% for pediatric lung condition (P<0.001). In adult lung configurations, Monnal T50 systematically over delivered VT and Trilogy 150 was sensitive to lung configuration when VT was set to 300 mL at either positive end-expiratory pressure (PEEP). Conclusions HCV are different in terms of FIO2 efficiency and VT delivery. PMID:28149559

Synchrotron-based dynamic computed tomography of tissue motion for regional lung function measurement

PubMed Central

Dubsky, Stephen; Hooper, Stuart B.; Siu, Karen K. W.; Fouras, Andreas

2012-01-01

During breathing, lung inflation is a dynamic process involving a balance of mechanical factors, including trans-pulmonary pressure gradients, tissue compliance and airway resistance. Current techniques lack the capacity for dynamic measurement of ventilation in vivo at sufficient spatial and temporal resolution to allow the spatio-temporal patterns of ventilation to be precisely defined. As a result, little is known of the regional dynamics of lung inflation, in either health or disease. Using fast synchrotron-based imaging (up to 60 frames s−1), we have combined dynamic computed tomography (CT) with cross-correlation velocimetry to measure regional time constants and expansion within the mammalian lung in vivo. Additionally, our new technique provides estimation of the airflow distribution throughout the bronchial tree during the ventilation cycle. Measurements of lung expansion and airflow in mice and rabbit pups are shown to agree with independent measures. The ability to measure lung function at a regional level will provide invaluable information for studies into normal and pathological lung dynamics, and may provide new pathways for diagnosis of regional lung diseases. Although proof-of-concept data were acquired on a synchrotron, the methodology developed potentially lends itself to clinical CT scanning and therefore offers translational research opportunities. PMID:22491972

Deviation of tracheal pressure from airway opening pressure during high-frequency oscillatory ventilation in a porcine lung model.

PubMed

Johannes, Amélie; Zollhoefer, Bernd; Eujen, Ulrike; Kredel, Markus; Rauch, Stefan; Roewer, Norbert; Muellenbach, Ralf M

2013-04-01

Oxygenation during high-frequency oscillatory ventilation is secured by a high level of mean airway pressure. Our objective was to identify a pressure difference between the airway opening of the respiratory circuit and the trachea during application of different oscillatory frequencies. Six female Pietrain pigs (57.1 ± 3.6 kg) were first ventilated in a conventional mechanical ventilation mode. Subsequently, the animals were switched to high-frequency oscillatory ventilation by setting mean airway opening pressure 5 cmH(2)O above the one measured during controlled mechanical ventilation. Measurements at the airway opening and at tracheal levels were performed in healthy lungs and after induction of acute lung injury by surfactant depletion. During high-frequency oscillatory ventilation, the airway opening pressure was set at a constant level. The pressure amplitude was fixed at 90 cmH(2)O. Starting from an oscillatory frequency of 3 Hz, the frequency was increased in steps of 3 Hz to 15 Hz and then decreased accordingly. At each frequency, measurements were performed in the trachea through a side-lumen of the endotracheal tube and the airway opening pressure was recorded. The pressure difference was calculated. At every oscillatory frequency, a pressure loss towards the trachea could be shown. This pressure difference increased with higher oscillatory frequencies (3 Hz 2.2 ± 2.1 cmH(2)O vs. 15 Hz 7.5 ± 1.8 cmH(2)O). The results for healthy and injured lungs were similar. Tracheal pressures decreased with higher oscillatory frequencies. This may lead to pulmonary derecruitment. This has to be taken into consideration when increasing oscillatory frequencies and differentiated pressure settings are mandatory.

Mechanical ventilation in abdominal surgery.

PubMed

Futier, E; Godet, T; Millot, A; Constantin, J-M; Jaber, S

2014-01-01

One of the key challenges in perioperative care is to reduce postoperative morbidity and mortality. Patients who develop postoperative morbidity but survive to leave hospital have often reduced functional independence and long-term survival. Mechanical ventilation provides a specific example that may help us to shift thinking from treatment to prevention of postoperative complications. Mechanical ventilation in patients undergoing surgery has long been considered only as a modality to ensure gas exchange while allowing maintenance of anesthesia with delivery of inhaled anesthetics. Evidence is accumulating, however, suggesting an association between intraoperative mechanical ventilation strategy and postoperative pulmonary function and clinical outcome in patients undergoing abdominal surgery. Non-protective ventilator settings, especially high tidal volume (VT) (>10-12mL/kg) and the use of very low level of positive end-expiratory pressure (PEEP) (PEEP<5cmH2O) or no PEEP, may cause alveolar overdistension and repetitive tidal recruitment leading to ventilator-associated lung injury in patients with healthy lungs. Stimulated by previous findings in patients with acute respiratory distress syndrome, the use of lower tidal volume ventilation is becoming increasingly more common in the operating room. However, lowering tidal volume, though important, is only part of the overall multifaceted approach of lung protective mechanical ventilation. In this review, we aimed at providing the most recent and relevant clinical evidence regarding the use of mechanical ventilation in patients undergoing abdominal surgery. Copyright © 2014 Société française d’anesthésie et de réanimation (Sfar). Published by Elsevier SAS. All rights reserved.

Novel analysis of 4DCT imaging quantifies progressive increases in anatomic dead space during mechanical ventilation in mice.

PubMed

Kim, Elizabeth H; Preissner, Melissa; Carnibella, Richard P; Samarage, Chaminda R; Bennett, Ellen; Diniz, Marcio A; Fouras, Andreas; Zosky, Graeme R; Jones, Heather D

2017-09-01

Increased dead space is an important prognostic marker in early acute respiratory distress syndrome (ARDS) that correlates with mortality. The cause of increased dead space in ARDS has largely been attributed to increased alveolar dead space due to ventilation/perfusion mismatching and shunt. We sought to determine whether anatomic dead space also increases in response to mechanical ventilation. Mice received intratracheal lipopolysaccharide (LPS) or saline and mechanical ventilation (MV). Four-dimensional computed tomography (4DCT) scans were performed at onset of MV and after 5 h of MV. Detailed measurements of airway volumes and lung tidal volumes were performed using image analysis software. The forced oscillation technique was used to obtain measures of airway resistance, tissue damping, and tissue elastance. The ratio of airway volumes to total tidal volume increased significantly in response to 5 h of mechanical ventilation, regardless of LPS exposure, and airways demonstrated significant variation in volumes over the respiratory cycle. These findings were associated with an increase in tissue elastance (decreased lung compliance) but without changes in tidal volumes. Airway volumes increased over time with exposure to mechanical ventilation without a concomitant increase in tidal volumes. These findings suggest that anatomic dead space fraction increases progressively with exposure to positive pressure ventilation and may represent a pathological process. NEW & NOTEWORTHY We demonstrate that anatomic dead space ventilation increases significantly over time in mice in response to mechanical ventilation. The novel functional lung-imaging techniques applied here yield sensitive measures of airway volumes that may have wide applications. Copyright © 2017 the American Physiological Society.

Cardiopulmonary function and oxygen delivery during total liquid ventilation.

PubMed

Tsagogiorgas, Charalambos; Alb, Markus; Herrmann, Peter; Quintel, Michael; Meinhardt, Juergen P

2011-10-01

Total liquid ventilation (TLV) with perfluorocarbons has shown to improve cardiopulmonary function in the injured and immature lung; however there remains controversy over the normal lung. Hemodynamic effects of TLV in the normal lung currently remain undetermined. This study compared changes in cardiopulmonary and circulatory function caused by either liquid or gas tidal volume ventilation. In a prospective, controlled study, 12 non-injured anesthetized, adult New Zealand rabbits were primarily conventionally gas-ventilated (CGV). After instrumentation for continuous recording of arterial (AP), central venous (CVP), left artrial (LAP), pulmonary arterial pressures (PAP), and cardiac output (CO) animals were randomized into (1) CGV group and (2) TLV group. In the TLV group partial liquid ventilation was initiated with instillation of perfluoroctylbromide (12 ml/kg). After 15 min, TLV was established for 3 hr applying a volume-controlled, pressure-limited, time-cycled ventilation mode using a double-piston configured TLV. Controls (CGV) remained gas-ventilated throughout the experiment. During TLV, heart rate, CO, PAP, MAP, CVP, and LAP as well as derived hemodynamic variables, arterial and mixed venous blood gases, oxygen delivery, PVR, and SVR did not differ significantly compared to CGV. Liquid tidal volumes suitable for long-term TLV in non-injured rabbits do not significantly impair CO, blood pressure, and oxygen dynamics when compared to CGV. Copyright © 2011 Wiley-Liss, Inc.

Preemptive mechanical ventilation can block progressive acute lung injury.

PubMed

Sadowitz, Benjamin; Jain, Sumeet; Kollisch-Singule, Michaela; Satalin, Joshua; Andrews, Penny; Habashi, Nader; Gatto, Louis A; Nieman, Gary

2016-02-04

Mortality from acute respiratory distress syndrome (ARDS) remains unacceptable, approaching 45% in certain high-risk patient populations. Treating fulminant ARDS is currently relegated to supportive care measures only. Thus, the best treatment for ARDS may lie with preventing this syndrome from ever occurring. Clinical studies were examined to determine why ARDS has remained resistant to treatment over the past several decades. In addition, both basic science and clinical studies were examined to determine the impact that early, protective mechanical ventilation may have on preventing the development of ARDS in at-risk patients. Fulminant ARDS is highly resistant to both pharmacologic treatment and methods of mechanical ventilation. However, ARDS is a progressive disease with an early treatment window that can be exploited. In particular, protective mechanical ventilation initiated before the onset of lung injury can prevent the progression to ARDS. Airway pressure release ventilation (APRV) is a novel mechanical ventilation strategy for delivering a protective breath that has been shown to block progressive acute lung injury (ALI) and prevent ALI from progressing to ARDS. ARDS mortality currently remains as high as 45% in some studies. As ARDS is a progressive disease, the key to treatment lies with preventing the disease from ever occurring while it remains subclinical. Early protective mechanical ventilation with APRV appears to offer substantial benefit in this regard and may be the prophylactic treatment of choice for preventing ARDS.

Effects of staff training and electronic event monitoring on long-term adherence to lung-protective ventilation recommendations.

PubMed

Castellanos, Ixchel; Martin, Marcus; Kraus, Stefan; Bürkle, Thomas; Prokosch, Hans-Ulrich; Schüttler, Jürgen; Toddenroth, Dennis

2018-02-01

To investigate long-term effects of staff training and electronic clinical decision support (CDS) on adherence to lung-protective ventilation recommendations. In 2012, group instructions and workshops at two surgical intensive care units (ICUs) started, focusing on standardized protocols for mechanical ventilation and volutrauma prevention. Subsequently implemented CDS functions continuously monitor ventilation parameters, and from 2015 triggered graphical notifications when tidal volume (V T ) violated individual thresholds. To estimate the effects of these educational and technical interventions, we retrospectively analyzed nine years of V T records from routine care. As outcome measures, we calculated relative frequencies of settings that conform to recommendations, case-specific mean excess V T , and total ICU survival. Assessing 571,478 V T records from 10,241 ICU cases indicated that adherence during pressure-controlled ventilation improved significantly after both interventions; the share of conforming V T records increased from 61.6% to 83.0% and then 86.0%. Despite increasing case severity, ICU survival remained nearly constant over time. Staff training effectively improves adherence to lung-protective ventilation strategies. The observed CDS effect seemed less pronounced, although it can easily be adapted to new recommendations. Both interventions, which futures studies could deploy in combination, promise to improve the precision of mechanical ventilation. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Preemptive mechanical ventilation can block progressive acute lung injury

PubMed Central

Sadowitz, Benjamin; Jain, Sumeet; Kollisch-Singule, Michaela; Satalin, Joshua; Andrews, Penny; Habashi, Nader; Gatto, Louis A; Nieman, Gary

2016-01-01

Mortality from acute respiratory distress syndrome (ARDS) remains unacceptable, approaching 45% in certain high-risk patient populations. Treating fulminant ARDS is currently relegated to supportive care measures only. Thus, the best treatment for ARDS may lie with preventing this syndrome from ever occurring. Clinical studies were examined to determine why ARDS has remained resistant to treatment over the past several decades. In addition, both basic science and clinical studies were examined to determine the impact that early, protective mechanical ventilation may have on preventing the development of ARDS in at-risk patients. Fulminant ARDS is highly resistant to both pharmacologic treatment and methods of mechanical ventilation. However, ARDS is a progressive disease with an early treatment window that can be exploited. In particular, protective mechanical ventilation initiated before the onset of lung injury can prevent the progression to ARDS. Airway pressure release ventilation (APRV) is a novel mechanical ventilation strategy for delivering a protective breath that has been shown to block progressive acute lung injury (ALI) and prevent ALI from progressing to ARDS. ARDS mortality currently remains as high as 45% in some studies. As ARDS is a progressive disease, the key to treatment lies with preventing the disease from ever occurring while it remains subclinical. Early protective mechanical ventilation with APRV appears to offer substantial benefit in this regard and may be the prophylactic treatment of choice for preventing ARDS. PMID:26855896

Acute refractory hypoxemia after chest trauma reversed by high-frequency oscillatory ventilation: a case report

PubMed Central

2013-01-01

Introduction Polytrauma often results in significant hypoxemia secondary to direct lung contusion or indirectly through atelectasis, systemic inflammatory response, large volume fluid resuscitation and blood product transfusion. In addition to causing hypoxemia, atelectasis and acute lung injury can lead to right ventricular failure through an acute increase in pulmonary vascular resistance. Mechanical ventilation is often applied, accompanied with recruitment maneuvers and positive end-expiratory pressure in order to recruit alveoli and reverse atelectasis, while preventing excessive alveolar damage. This strategy should lead to the reversal of the hypoxemic condition and the detrimental heart–lung interaction that may occur. However, as described in this case report, hemodynamic instability and intractable alveolar atelectasis sometimes do not respond to conventional ventilation strategies. Case presentation We describe the case of a 21-year-old Caucasian man with severe chest trauma requiring surgical interventions, who developed refractory hypoxemia and overt right ventricular failure. After multiple failed attempts of recruitment using conventional ventilation, the patient was ventilated with high-frequency oscillatory ventilation. This mode of ventilation allowed the reversal of the hemodynamic effects of severe hypoxemia and of the acute cor pulmonale. We use this case report to describe the physiological advantages of high-frequency oscillatory ventilation in patients with chest trauma, and formulate the arguments to explain the positive effect observed in our patient. Conclusions High-frequency oscillatory ventilation can be used in the context of a blunt chest trauma accompanied by severe hypoxemia due to atelectasis. The positive effect is due to its capacity to recruit the collapsed alveoli and, as a result, the relief of increased pulmonary vascular resistance and subsequently the reversal of acute cor pulmonale. This approach may represent an alternative in case of failure of the conventional ventilation strategy. PMID:23855954

WE-AB-202-02: Incorporating Regional Ventilation Function in Predicting Radiation Fibrosis After Concurrent Chemoradiotherapy for Lung Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lan, F; Jeudy, J; Tseng, H

Purpose: To investigate the incorporation of pre-therapy regional ventilation function in predicting radiation fibrosis (RF) in stage III non-small-cell lung cancer (NSCLC) patients treated with concurrent thoracic chemoradiotherapy. Methods: 37 stage III NSCLC patients were retrospectively studied. Patients received one cycle of cisplatin-gemcitabine, followed by two to three cycles of cisplatin-etoposide concurrently with involved-field thoracic radiotherapy between 46 and 66 Gy (2 Gy per fraction). Pre-therapy regional ventilation images of the lung were derived from 4DCT via a density-change-based image registration algorithm with mass correction. RF was evaluated at 6-months post-treatment using radiographic scoring based on airway dilation and volumemore » loss. Three types of ipsilateral lung metrics were studied: (1) conventional dose-volume metrics (V20, V30, V40, and mean-lung-dose (MLD)), (2) dose-function metrics (fV20, fV30, fV40, and functional mean-lung-dose (fMLD) generated by combining regional ventilation and dose), and (3) dose-subvolume metrics (sV20, sV30, sV40, and subvolume mean-lung-dose (sMLD) defined as the dose-volume metrics computed on the sub-volume of the lung with at least 60% of the quantified maximum ventilation status). Receiver operating characteristic (ROC) curve analysis and logistic regression analysis were used to evaluate the predictability of these metrics for RF. Results: In predicting airway dilation, the area under the ROC curve (AUC) values for (V20, MLD), (fV20, fMLD), and (sV20, and sMLD) were (0.76, 0.70), (0.80, 0.74) and (0.82, 0.80), respectively. The logistic regression p-values were (0.09, 0.18), (0.02, 0.05) and (0.004, 0.006), respectively. With regard to volume loss, the corresponding AUC values for these metrics were (0.66, 0.57), (0.67, 0.61) and (0.71, 0.69), and p-values were (0.95, 0.90), (0.43, 0.64) and (0.08, 0.12), respectively. Conclusion: The inclusion of regional ventilation function improved predictability of radiation fibrosis. Dose-subvolume metrics provided a promising method for incorporating functional information into the conventional dose-volume parameters for outcome assessment.« less

Evidence for Avian Intrathoracic Air Sacs in a New Predatory Dinosaur from Argentina

PubMed Central

Sereno, Paul C.; Martinez, Ricardo N.; Wilson, Jeffrey A.; Varricchio, David J.; Alcober, Oscar A.; Larsson, Hans C. E.

2008-01-01

Background Living birds possess a unique heterogeneous pulmonary system composed of a rigid, dorsally-anchored lung and several compliant air sacs that operate as bellows, driving inspired air through the lung. Evidence from the fossil record for the origin and evolution of this system is extremely limited, because lungs do not fossilize and because the bellow-like air sacs in living birds only rarely penetrate (pneumatize) skeletal bone and thus leave a record of their presence. Methodology/Principal Findings We describe a new predatory dinosaur from Upper Cretaceous rocks in Argentina, Aerosteon riocoloradensis gen. et sp. nov., that exhibits extreme pneumatization of skeletal bone, including pneumatic hollowing of the furcula and ilium. In living birds, these two bones are pneumatized by diverticulae of air sacs (clavicular, abdominal) that are involved in pulmonary ventilation. We also describe several pneumatized gastralia (“stomach ribs”), which suggest that diverticulae of the air sac system were present in surface tissues of the thorax. Conclusions/Significance We present a four-phase model for the evolution of avian air sacs and costosternal-driven lung ventilation based on the known fossil record of theropod dinosaurs and osteological correlates in extant birds: (1) Phase I—Elaboration of paraxial cervical air sacs in basal theropods no later than the earliest Late Triassic. (2) Phase II—Differentiation of avian ventilatory air sacs, including both cranial (clavicular air sac) and caudal (abdominal air sac) divisions, in basal tetanurans during the Jurassic. A heterogeneous respiratory tract with compliant air sacs, in turn, suggests the presence of rigid, dorsally attached lungs with flow-through ventilation. (3) Phase III—Evolution of a primitive costosternal pump in maniraptoriform theropods before the close of the Jurassic. (4) Phase IV—Evolution of an advanced costosternal pump in maniraptoran theropods before the close of the Jurassic. In addition, we conclude: (5) The advent of avian unidirectional lung ventilation is not possible to pinpoint, as osteological correlates have yet to be identified for uni- or bidirectional lung ventilation. (6) The origin and evolution of avian air sacs may have been driven by one or more of the following three factors: flow-through lung ventilation, locomotory balance, and/or thermal regulation. PMID:18825273

Increased lung inflammation with oxygen supplementation in tracheotomized spontaneously breathing rabbits: an experimental prospective randomized study.

PubMed

Machado, Humberto S; Nunes, Catarina S; Sá, Paula; Couceiro, Antonio; da Silva, Álvaro Moreira; Águas, Artur

2014-01-01

Mechanical ventilation is a well-known trigger for lung inflammation. Research focuses on tidal volume reduction to prevent ventilator-induced lung injury. Mechanical ventilation is usually applied with higher than physiological oxygen fractions. The purpose of this study was to investigate the after effect of oxygen supplementation during a spontaneous ventilation set up, in order to avoid the inflammatory response linked to mechanical ventilation. A prospective randomised study using New Zealand rabbits in a university research laboratory was carried out. Rabbits (n = 20) were randomly assigned to 4 groups (n = 5 each group). Groups 1 and 2 were submitted to 0.5 L/min oxygen supplementation, for 20 or 75 minutes, respectively; groups 3 and 4 were left at room air for 20 or 75 minutes. Ketamine/xylazine was administered for induction and maintenance of anaesthesia. Lungs were obtained for histological examination in light microscopy. All animals survived the complete experiment. Procedure duration did not influence the degree of inflammatory response. The hyperoxic environment was confirmed by blood gas analyses in animals that were subjected to oxygen supplementation, and was accompanied with lower mean respiratory rates. The non-oxygen supplemented group had lower mean oxygen arterial partial pressures and higher mean respiratory rates during the procedure. All animals showed some inflammatory lung response. However, rabbits submitted to oxygen supplementation showed significant more lung inflammation (Odds ratio = 16), characterized by more infiltrates and with higher cell counts; the acute inflammatory response cells was mainly constituted by eosinophils and neutrophils, with a relative proportion of 80 to 20% respectively. This cellular observation in lung tissue did not correlate with a similar increase in peripheral blood analysis. Oxygen supplementation in spontaneous breathing is associated with an increased inflammatory response when compared to breathing normal room air. This inflammatory response was mainly constituted with polymorphonuclear cells (eosinophils and neutrophils). As confirmed in all animals by peripheral blood analyses, the eosinophilic inflammatory response was a local organ event.

The effect of low level laser therapy on ventilator-induced lung injury in mice (Conference Presentation)

NASA Astrophysics Data System (ADS)

Szabari, Margit V.; Miller, Alyssa J.; Hariri, Lida P.; Hamblin, Michael R.; Musch, Guido; Stroh, Helene; Suter, Melissa J.

2016-03-01

Although mechanical ventilation (MV) is necessary to support gas exchange in critically ill patients, it can contribute to the development of lung injury and multiple organ dysfunction. It is known that high tidal volume (Vt) MV can cause ventilator-induced lung injury (VILI) in healthy lungs and increase the mortality of patients with Acute Respiratory Distress Syndrome. Low level laser therapy (LLLT) has demonstrated to have anti-inflammatory effects. We investigated whether LLLT could alleviate inflammation from injurious MV in mice. Adult mice were assigned to 2 groups: VILI+LLLT group (3 h of injurious MV: Vt=25-30 ml/kg, respiratory rate (RR)=50/min, positive end-expiratory pressure (PEEP)=0 cmH20, followed by 3 h of protective MV: Vt=9 ml/kg, RR=140/min, PEEP=2 cmH20) and VILI+no LLLT group. LLLT was applied during the first 30 min of the MV (810 nm LED system, 5 J/cm2, 1 cm above the chest). Respiratory impedance was measured in vivo with forced oscillation technique and lung mechanics were calculated by fitting the constant phase model. At the end of the MV, bronchoalveolar lavage (BAL) was performed and inflammatory cells counted. Lungs were removed en-bloc and fixed for histological evaluation. We hypothesize that LLLT can reduce lung injury and inflammation from VILI. This therapy could be translated into clinical practice, where it can potentially improve outcomes in patients requiring mechanical ventilation in the operating room or in the intensive care units.

Partial liquid ventilation with perfluorocarbon improves gas exchange and decreases inflammatory response in oleic acid-induced lung injury in beagles.

PubMed

Suh, G Y; Chung, M P; Park, S J; Park, J W; Kim, H C; Kim, H; Han, J; Rhee, C H; Kwon, O J

1999-12-01

The aim of this study was to determine the effect of partial liquid ventilation (PLV) using a perfluorocarbon (PFC) on gas exchange and lung inflammatory response in a canine acute lung injury model. After inducing severe lung injury by oleic acid infusion, beagle dogs were randomized to receive either gas ventilation only (control group, n = 6) or PLV (PLV group, n = 7) by sequential instillation of 10 mL/kg of perfluorodecalin (PFC) at 30 min intervals till functional residual capacity was attained. Measurements were made every 30 min till 210 min. Then the lungs were removed and bronchoalveolar lavage (BAL) (35 mL/kg) was performed on the right lung and the left lung was submitted for histologic analysis. There was significant improvement in PaO2 and PaCO2 in the PLV group compared to the control group (p < 0.05) which was associated with a significant decrease in shunt (p < 0.05). There was no significant difference in parameters of lung mechanics and hemodynamics. There was a significant decrease in cell count and neutrophil percentage in BAL fluid and significantly less inflammation and exudate scores in histology in the PLV group (p < 0.05). We conclude that PLV with perfluorodecalin improves gas exchange and decreases inflammatory response in the acutely-injured lung.

[Clinical efficacy of one-lung ventilation in treatment of children postoperatively intractable atelectasis].

PubMed

Huo, J M; Bai, K; Fu, Y Q; Liu, C J; Xu, F

2017-11-02

Objective: To investigate the effect of fiberoptic bronchoscope-guided one-lung ventilation (OLV) on treatment of intractable atelectasis in children. Method: This retrospective cohort study was conducted in Pediatric Intensive Care Unit, Children's Hospital of Chongqing Medical University from December 2014 to May 2017. Six patients with intractable atelectasis of left lung were included. Three cases were male and three female with the age from 1.5 to 11.0 years. The endotracheal tube was intubated to the left main bronchus for OLV by the guidance of fiberoptic bronchoscopy. The effect of treatment by monitoring the chest imaging after treatment was evaluated. Result: Six pediatric patients were successfully cured by OLV. The duration of OLV ranged from 1.5 to 30.0 hours, and the intervals of OLV were usually 3 to 5 days. Each patient received 6 to 20 OLV treatments. Chest images showed the left lung reexpanded obviously after OLV treatments. Five patients successfully weaned from invasive ventilation and were discharged. Another patient turned better, discharged from hospital with noninvasive ventilation and weaned from noninvasive ventilation one month later after discharge. During the procedure of OLV, the vital signs of all patients were stable and no complication occurred. Conclusion: OLV with selective bronchial intubation guided by fiber bronchoscope is a safe and effective treatment for intractable atelectasis in children.

Purinergic signalling links mechanical breath profile and alveolar mechanics with the pro-inflammatory innate immune response causing ventilation-induced lung injury.

PubMed

Hasan, Djo; Blankman, Paul; Nieman, Gary F

2017-09-01

Severe pulmonary infection or vigorous cyclic deformation of the alveolar epithelial type I (AT I) cells by mechanical ventilation leads to massive extracellular ATP release. High levels of extracellular ATP saturate the ATP hydrolysis enzymes CD39 and CD73 resulting in persistent high ATP levels despite the conversion to adenosine. Above a certain level, extracellular ATP molecules act as danger-associated molecular patterns (DAMPs) and activate the pro-inflammatory response of the innate immunity through purinergic receptors on the surface of the immune cells. This results in lung tissue inflammation, capillary leakage, interstitial and alveolar oedema and lung injury reducing the production of surfactant by the damaged AT II cells and deactivating the surfactant function by the concomitant extravasated serum proteins through capillary leakage followed by a substantial increase in alveolar surface tension and alveolar collapse. The resulting inhomogeneous ventilation of the lungs is an important mechanism in the development of ventilation-induced lung injury. The high levels of extracellular ATP and the upregulation of ecto-enzymes and soluble enzymes that hydrolyse ATP to adenosine (CD39 and CD73) increase the extracellular adenosine levels that inhibit the innate and adaptive immune responses rendering the host susceptible to infection by invading microorganisms. Moreover, high levels of extracellular adenosine increase the expression, the production and the activation of pro-fibrotic proteins (such as TGF-β, α-SMA, etc.) followed by the establishment of lung fibrosis.

[Pulmonary-renal crosstalk in the critically ill patient].

PubMed

Donoso F, Alejandro; Arriagada S, Daniela; Cruces R, Pablo

2015-01-01

Despite advances in the development of renal replacement therapy, mortality of acute renal failure remains high, especially when occurring simultaneously with distant organic failure as it is in the case of the acute respiratory distress syndrome. In this update, birideccional deleterious relationship between lung and kidney on the setting of organ dysfunction is reviewed, which presents important clinical aspects of knowing. Specifically, the renal effects of acute respiratory distress syndrome and the use of positive-pressure mechanical ventilation are discussed, being ventilator induced lung injury one of the most common models for studying the lung-kidney crosstalk. The role of renal failure induced by mechanical ventilation (ventilator-induced kidney injury) in the pathogenesis of acute renal failure is emphasized. We also analyze the impact of the acute renal failure in the lung, recognizing an increase in pulmonary vascular permeability, inflammation, and alteration of sodium and water channels in the alveolar epithelial. This conceptual model can be the basis for the development of new therapeutic strategies to use in patients with multiple organ dysfunction syndrome. Copyright © 2015 Sociedad Chilena de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

Short-term effects of physiotherapy on ventilation inhomogeneity in cystic fibrosis patients with a wide range of lung disease severity.

PubMed

Pfleger, A; Steinbacher, M; Schwantzer, G; Weinhandl, E; Wagner, M; Eber, E

2015-09-01

Lung clearance index (LCI) is increasingly used as a study endpoint for therapeutic interventions in cystic fibrosis (CF) patients. We set out to assess the effect of chest physiotherapy on ventilation inhomogeneity in clinically stable patients with CF lung disease of varying severity. In 29 CF patients (7.3-43.7 years) N2MBW (nitrogen multiple breath washout), plethysmography, and spirometry measurements were conducted, followed by 30 min of supervised PEP mask chest physiotherapy and repeated measurements 30 min after therapy. We observed a mean change in LCI after physiotherapy from 15.00 to 14.80 (range, -4.84 to 3.37; p=0.578). In seven patients, LCI decreased, and in ten patients, LCI increased by ≥1. For the whole group, statistically significant improvements were seen in Reff, FEV1, FVC, and MEF50. By opening up previously poorly ventilated lung regions, physiotherapy may either increase or decrease ventilation inhomogeneity; the short-term effect of physiotherapy on LCI appears to be unpredictable. Copyright © 2015 European Cystic Fibrosis Society. Published by Elsevier B.V. All rights reserved.

Lung-Protective Ventilation Initiated in the Emergency Department (LOV-ED): A Quasi-Experimental, Before-After Trial.

PubMed

Fuller, Brian M; Ferguson, Ian T; Mohr, Nicholas M; Drewry, Anne M; Palmer, Christopher; Wessman, Brian T; Ablordeppey, Enyo; Keeperman, Jacob; Stephens, Robert J; Briscoe, Cristopher C; Kolomiets, Angelina A; Hotchkiss, Richard S; Kollef, Marin H

2017-09-01

We evaluated the efficacy of an emergency department (ED)-based lung-protective mechanical ventilation protocol for the prevention of pulmonary complications. This was a quasi-experimental, before-after study that consisted of a preintervention period, a run-in period of approximately 6 months, and a prospective intervention period. The intervention was a multifaceted ED-based mechanical ventilator protocol targeting lung-protective tidal volume, appropriate setting of positive end-expiratory pressure, rapid oxygen weaning, and head-of-bed elevation. A propensity score-matched analysis was used to evaluate the primary outcome, which was the composite incidence of acute respiratory distress syndrome and ventilator-associated conditions. A total of 1,192 patients in the preintervention group and 513 patients in the intervention group were included. Lung-protective ventilation increased by 48.4% in the intervention group. In the propensity score-matched analysis (n=490 in each group), the primary outcome occurred in 71 patients (14.5%) in the preintervention group compared with 36 patients (7.4%) in the intervention group (adjusted odds ratio 0.47; 95% confidence interval [CI] 0.31 to 0.71). There was an increase in ventilator-free days (mean difference 3.7; 95% CI 2.3 to 5.1), ICU-free days (mean difference 2.4; 95% CI 1.0 to 3.7), and hospital-free days (mean difference 2.4; 95% CI 1.2 to 3.6) associated with the intervention. The mortality rate was 34.1% in the preintervention group and 19.6% in the intervention group (adjusted odds ratio 0.47; 95% CI 0.35 to 0.63). Implementing a mechanical ventilator protocol in the ED is feasible and is associated with significant improvements in the delivery of safe mechanical ventilation and clinical outcome. Copyright © 2017 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

Spatial correspondence of 4D CT ventilation and SPECT pulmonary perfusion defects in patients with malignant airway stenosis

NASA Astrophysics Data System (ADS)

Castillo, Richard; Castillo, Edward; McCurdy, Matthew; Gomez, Daniel R.; Block, Alec M.; Bergsma, Derek; Joy, Sarah; Guerrero, Thomas

2012-04-01

To determine the spatial overlap agreement between four-dimensional computed tomography (4D CT) ventilation and single photon emission computed tomography (SPECT) perfusion hypo-functioning pulmonary defect regions in a patient population with malignant airway stenosis. Treatment planning 4D CT images were obtained retrospectively for ten lung cancer patients with radiographically demonstrated airway obstruction due to gross tumor volume. Each patient also received a SPECT perfusion study within one week of the planning 4D CT, and prior to the initiation of treatment. Deformable image registration was used to map corresponding lung tissue elements between the extreme component phase images, from which quantitative three-dimensional (3D) images representing the local pulmonary specific ventilation were constructed. Semi-automated segmentation of the percentile perfusion distribution was performed to identify regional defects distal to the known obstructing lesion. Semi-automated segmentation was similarly performed by multiple observers to delineate corresponding defect regions depicted on 4D CT ventilation. Normalized Dice similarity coefficient (NDSC) indices were determined for each observer between SPECT perfusion and 4D CT ventilation defect regions to assess spatial overlap agreement. Tidal volumes determined from 4D CT ventilation were evaluated versus measurements obtained from lung parenchyma segmentation. Linear regression resulted in a linear fit with slope = 1.01 (R2 = 0.99). Respective values for the average DSC, NDSC1 mm and NDSC2 mm for all cases and multiple observers were 0.78, 0.88 and 0.99, indicating that, on average, spatial overlap agreement between ventilation and perfusion defect regions was comparable to the threshold for agreement within 1-2 mm uncertainty. Corresponding coefficients of variation for all metrics were similarly in the range: 0.10%-19%. This study is the first to quantitatively assess 3D spatial overlap agreement between clinically acquired SPECT perfusion and specific ventilation from 4D CT. Results suggest high correlation between methods within the sub-population of lung cancer patients with malignant airway stenosis.

Automated pulmonary lobar ventilation measurements using volume-matched thoracic CT and MRI

NASA Astrophysics Data System (ADS)

Guo, F.; Svenningsen, S.; Bluemke, E.; Rajchl, M.; Yuan, J.; Fenster, A.; Parraga, G.

2015-03-01

Objectives: To develop and evaluate an automated registration and segmentation pipeline for regional lobar pulmonary structure-function measurements, using volume-matched thoracic CT and MRI in order to guide therapy. Methods: Ten subjects underwent pulmonary function tests and volume-matched 1H and 3He MRI and thoracic CT during a single 2-hr visit. CT was registered to 1H MRI using an affine method that incorporated block-matching and this was followed by a deformable step using free-form deformation. The resultant deformation field was used to deform the associated CT lobe mask that was generated using commercial software. 3He-1H image registration used the same two-step registration method and 3He ventilation was segmented using hierarchical k-means clustering. Whole lung and lobar 3He ventilation and ventilation defect percent (VDP) were generated by mapping ventilation defects to CT-defined whole lung and lobe volumes. Target CT-3He registration accuracy was evaluated using region- , surface distance- and volume-based metrics. Automated whole lung and lobar VDP was compared with semi-automated and manual results using paired t-tests. Results: The proposed pipeline yielded regional spatial agreement of 88.0+/-0.9% and surface distance error of 3.9+/-0.5 mm. Automated and manual whole lung and lobar ventilation and VDP were not significantly different and they were significantly correlated (r = 0.77, p < 0.0001). Conclusion: The proposed automated pipeline can be used to generate regional pulmonary structural-functional maps with high accuracy and robustness, providing an important tool for image-guided pulmonary interventions.

Respiratory mechanics in mechanically ventilated patients.

PubMed

Hess, Dean R

2014-11-01

Respiratory mechanics refers to the expression of lung function through measures of pressure and flow. From these measurements, a variety of derived indices can be determined, such as volume, compliance, resistance, and work of breathing. Plateau pressure is a measure of end-inspiratory distending pressure. It has become increasingly appreciated that end-inspiratory transpulmonary pressure (stress) might be a better indicator of the potential for lung injury than plateau pressure alone. This has resulted in a resurgence of interest in the use of esophageal manometry in mechanically ventilated patients. End-expiratory transpulmonary pressure might also be useful to guide the setting of PEEP to counterbalance the collapsing effects of the chest wall. The shape of the pressure-time curve might also be useful to guide the setting of PEEP (stress index). This has focused interest in the roles of stress and strain to assess the potential for lung injury during mechanical ventilation. This paper covers both basic and advanced respiratory mechanics during mechanical ventilation. Copyright © 2014 by Daedalus Enterprises.

High tidal volume ventilation in infant mice.

PubMed

Cannizzaro, Vincenzo; Zosky, Graeme R; Hantos, Zoltán; Turner, Debra J; Sly, Peter D

2008-06-30

Infant mice were ventilated with either high tidal volume (V(T)) with zero end-expiratory pressure (HVZ), high V(T) with positive end-expiratory pressure (PEEP) (HVP), or low V(T) with PEEP. Thoracic gas volume (TGV) was determined plethysmographically and low-frequency forced oscillations were used to measure the input impedance of the respiratory system. Inflammatory cells, total protein, and cytokines in bronchoalveolar lavage fluid (BALF) and interleukin-6 (IL-6) in serum were measured as markers of pulmonary and systemic inflammatory response, respectively. Coefficients of tissue damping and tissue elastance increased in all ventilated mice, with the largest rise seen in the HVZ group where TGV rapidly decreased. BALF protein levels increased in the HVP group, whereas serum IL-6 rose in the HVZ group. PEEP keeps the lungs open, but provides high volumes to the entire lungs and induces lung injury. Compared to studies in adult and non-neonatal rodents, infant mice demonstrate a different response to similar ventilation strategies underscoring the need for age-specific animal models.

The concept of "baby lung".

PubMed

Gattinoni, Luciano; Pesenti, Antonio

2005-06-01

The "baby lung" concept originated as an offspring of computed tomography examinations which showed in most patients with acute lung injury/acute respiratory distress syndrome that the normally aerated tissue has the dimensions of the lung of a 5- to 6-year-old child (300-500 g aerated tissue). The respiratory system compliance is linearly related to the "baby lung" dimensions, suggesting that the acute respiratory distress syndrome lung is not "stiff" but instead small, with nearly normal intrinsic elasticity. Initially we taught that the "baby lung" is a distinct anatomical structure, in the nondependent lung regions. However, the density redistribution in prone position shows that the "baby lung" is a functional and not an anatomical concept. This provides a rational for "gentle lung treatment" and a background to explain concepts such as baro- and volutrauma. From a physiological perspective the "baby lung" helps to understand ventilator-induced lung injury. In this context, what appears dangerous is not the V(T)/kg ratio but instead the V(T)/"baby lung" ratio. The practical message is straightforward: the smaller the "baby lung," the greater is the potential for unsafe mechanical ventilation.

Intrapulmonary receptors in the Tegu lizard: I. Sensitivity to CO2.

PubMed

Feede, M R; Kuhlmann, W D; Scheid, P

1977-02-01

Single unit vagal recordings from intrapulmonary receptors were obtained in decerebrate, paralyzed lizards both during pump ventilation and during unidirectional ventilation on the cannulated, sack-shaped lung. Two types of receptors were identified: (1) CO2-receptors, which increased their discharge frequency as intrapulmonary CO2 concentration decreased but were not sensitive to stretch of the lung. (2) Mechanoreceptors, which rapidly increased discharge frequency when the lung was stretched. These receptors' CO2 sensitivity varied. Lungs of lizards thus appeared to possess both CO2 receptors, which have functional characteristics similar to those in birds, and mechanoreceptors with properties similar to stretch receptors in mammals.

Bias flow rate and ventilation efficiency during adult high-frequency oscillatory ventilation: a lung model study.

PubMed

Nagano, Osamu; Yumoto, Tetsuya; Nishimatsu, Atsunori; Kanazawa, Shunsuke; Fujita, Takahisa; Asaba, Sunao; Yamanouchi, Hideo

2018-04-19

Bias flow (BF) is essential to maintain mean airway pressure (MAP) and to washout carbon dioxide (CO 2 ) from the oscillator circuit during high-frequency oscillatory ventilation (HFOV). If the BF rate is inadequate, substantial CO 2 rebreathing could occur and ventilation efficiency could worsen. With lower ventilation efficiency, the required stroke volume (SV) would increase in order to obtain the same alveolar ventilation with constant frequency. The aim of this study was to assess the effect of BF rate on ventilation efficiency during adult HFOV. The R100 oscillator (Metran, Japan) was connected to an original lung model internally equipped with a simulated bronchial tree. The actual SV was measured with a flow sensor placed at the Y-piece. Carbon dioxide (CO 2 ) was continuously insufflated into the lung model ([Formula: see text]CO 2 ), and the partial pressure of CO 2 (PCO 2 ) in the lung model was monitored. Alveolar ventilation ([Formula: see text]A) was estimated as [Formula: see text]CO 2 divided by the stabilized value of PCO 2 . [Formula: see text]A was evaluated by setting SV from 80 to 180 mL (10 mL increments, n = 5) at a frequency of 8 Hz, a MAP of 25 cmH 2 O, and a BF of 10, 20, 30, and 40 L/min (study 1). Ventilation efficiency was calculated as [Formula: see text]A divided by the actual minute volume. The experiment was also performed with an actual SV of 80, 100, and 120 mL and a BF from 10 to 60 L/min (10 L/min increments: study 2). Study 1: With the same setting SV, the [Formula: see text]A with a BF of 20 L/min or more was significantly higher than that with a BF of 10 L/min. Study 2: With the same actual SV, the [Formula: see text]A and the ventilation efficiency with a BF of 30 L/min or more were significantly higher than those with a BF of 10 or 20 L/min. Increasing BF up to 30 L/min or more improved ventilation efficiency in the R100 oscillator.

Case Studies in Physiology: Ventilation and perfusion in a giraffe-does size matter?

PubMed

Nyman, Görel; Röken, Bengt; Hedin, Eva-Maria; Hedenstierna, Göran

2016-12-01

The trachea in the giraffe is long but narrow, and dead space ventilation is considered to be of approximately the same size as in other mammals. Less is known about the matching between ventilation and lung blood flow. The lungs in the giraffe are large, up to 1 m high and 0.7 m wide, and this may cause considerable ventilation/perfusion (V A /Q) mismatch due to the influence of gravitational forces, which could lead to hypoxemia. We studied a young giraffe under anesthesia using the multiple inert gas elimination technique to analyze the VA/Q distribution and arterial oxygenation and compared the results with those obtained in other species of different sizes, including humans. V A /Q distribution was broad but unimodal, and the shunt of blood flow through nonventilated lung regions was essentially absent, suggesting no lung collapse. The V A /Q match was as good as in the similarly sized horse and was even comparable to that in smaller sized animals, including rabbit and rat. The match was also similar to that in anesthetized humans. Arterial oxygenation was essentially similar in all studied species. The findings suggest that the efficiency of V A /Q matching is independent of lung size in the studied mammals that vary in weight from less than 1 to more than 400 kg. Copyright © 2016 the American Physiological Society.

[The first national program of pediatric lung transplantation: the experience in pediatric intensive care].

PubMed

Frías Pérez, M; Montero Schiemann, C; Ibarra de la Rosa, I; Ulloa Santamaría, E; Muñoz Bonet, J; Velasco Jabalquinto, M; Pérez Navero, J; Lama Martínez, R; Santos Luna, F; Salvatierra Velázquez, A; López Pujol, J

1999-06-01

The aim of this study was to analyze the postoperative progress and medical management in the Pediatric Intensive Care Unit (PICU) of patients that underwent bilateral lung transplant. From April 1997 to June 1998, 10 pediatric lung transplants were performed at the Hospital Reina Sofía (Córdoba, Spain). There were 4 males and 6 females (mean age 11.5 years, range 5 to 15 years). Indications for transplantation were cystic fibrosis (n = 9) and one pulmonary fibrosis secondary to viral infection. Before the transplant, two patients required mechanical ventilation for acute respiratory decompensation and one patient was ventilator-dependent. Immunosuppression consisted of corticosteroids, azathioprine and cyclosporine or tacrolimus. Post-transplantation management included early extubation, when possible, optimal fluid balance to prevent lung edema, low aggressive mechanical ventilation and adequate treatment of complications, such as rejection and infection. There were no peri-operative mortalities. The mean stay in the PICU was 28 days (median: 17 days) and the mean time on mechanical ventilation was 19 days (median: 5.5 days). The most frequent complications were rejection (n = 8), hyperglycemia (n = 6), renal failure (n = 4), arterial hypertension (n = 4) and respiratory infections (n = 3). There were no airway complications. Even if the post-operative period in pediatric lung transplant patients is difficult, the results have been good with an important improvement in the quality of life of these patients has been achieved.

EARLY STABILIZING ALVEOLAR VENTILATION PREVENTS ARDS- A NOVEL TIMING-BASED VENTILATORY INTERVENTION TO AVERT LUNG INJURY

PubMed Central

Roy, Shreyas; Sadowitz, Benjamin; Andrews, Penny; Gatto, Louis; Marx, William; Ge, Lin; Wang, Guirong; Lin, Xin; Dean, David A.; Kuhn, Michael; Ghosh, Auyon; Satalin, Joshua; Snyder, Kathy; Vodovotz, Yoram; Nieman, Gary; Habashi, Nader

2012-01-01

Background Established ARDS is often refractory to treatment. Clinical trials have demonstrated modest treatment effects, and mortality remains high. Ventilator strategies must be developed to prevent ARDS. Hypothesis Early ventilatory intervention will block progression to ARDS if the ventilator mode: 1) maintains alveolar stability and 2) reduces pulmonary edema formation. Methods Yorkshire Pigs (38–45kg) were anaesthetized and subjected to "2-hit" Ischemia-Reperfusion and Peritoneal Sepsis. Following injury, animals were randomized into two groups: Early Preventative Ventilation (Airway Pressure Release Ventilation- APRV) vs. Non-Preventative Ventilation (NPV) and followed for 48hr. All animals received anesthesia, antibiotics, and fluid/vasopressor therapy per Surviving Sepsis Campaign. Ventilation parameters: 1) NPV Group - Tidal volume (Vt): 10cc/kg + PEEP- 5 cm/H2O volume-cycled mode, 2) APRV Group - Vt: 10–15 cc/kg; Phigh, Plow, Thigh, Tlow were titrated for optimal alveolar stability. Physiologic data and plasma were collected throughout the 48hr study period, followed by BAL and necropsy. Results APRV prevented development of ARDS (p<0.001 vs NPV) by PaO2/FiO2 ratio. Quantitative histological scoring showed APRV prevented lung tissue injury (p<0.001 vs. NPV). BALF showed APRV lowered total protein and IL-6, while preserving surfactant proteins A & B (p<0.05 vs. NPV). APRV significantly lowered lung water (p<0.001 vs. NPV). Plasma IL-6 concentrations were similar between groups. Conclusions Early preventative mechanical ventilation with APRV blocked ARDS development, preserved surfactant proteins, and reduced pulmonary inflammation and edema, despite systemic inflammation similar to NPV. These data suggest early preventative ventilation strategies stabilizing alveoli and reducing pulmonary edema can attenuate ARDS after ischemia-reperfusion-sepsis. PMID:22846945

Mechanical Ventilation and ARDS in the ED

PubMed Central

Mohr, Nicholas M.; Miller, Christopher N.; Deitchman, Andrew R.; Castagno, Nicole; Hassebroek, Elizabeth C.; Dhedhi, Adam; Scott-Wittenborn, Nicholas; Grace, Edward; Lehew, Courtney; Kollef, Marin H.

2015-01-01

BACKGROUND: There are few data regarding mechanical ventilation and ARDS in the ED. This could be a vital arena for prevention and treatment. METHODS: This study was a multicenter, observational, prospective, cohort study aimed at analyzing ventilation practices in the ED. The primary outcome was the incidence of ARDS after admission. Multivariable logistic regression was used to determine the predictors of ARDS. RESULTS: We analyzed 219 patients receiving mechanical ventilation to assess ED ventilation practices. Median tidal volume was 7.6 mL/kg predicted body weight (PBW) (interquartile range, 6.9-8.9), with a range of 4.3 to 12.2 mL/kg PBW. Lung-protective ventilation was used in 122 patients (55.7%). The incidence of ARDS after admission from the ED was 14.7%, with a mean onset of 2.3 days. Progression to ARDS was associated with higher illness severity and intubation in the prehospital environment or transferring facility. Of the 15 patients with ARDS in the ED (6.8%), lung-protective ventilation was used in seven (46.7%). Patients who progressed to ARDS experienced greater duration in organ failure and ICU length of stay and higher mortality. CONCLUSIONS: Lung-protective ventilation is infrequent in patients receiving mechanical ventilation in the ED, regardless of ARDS status. Progression to ARDS is common after admission, occurs early, and worsens outcome. Patient- and treatment-related factors present in the ED are associated with ARDS. Given the limited treatment options for ARDS, and the early onset after admission from the ED, measures to prevent onset and to mitigate severity should be instituted in the ED. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT01628523; URL: www.clinicaltrials.gov PMID:25742126

Mechanical Ventilation and ARDS in the ED: A Multicenter, Observational, Prospective, Cross-sectional Study.

PubMed

Fuller, Brian M; Mohr, Nicholas M; Miller, Christopher N; Deitchman, Andrew R; Levine, Brian J; Castagno, Nicole; Hassebroek, Elizabeth C; Dhedhi, Adam; Scott-Wittenborn, Nicholas; Grace, Edward; Lehew, Courtney; Kollef, Marin H

2015-08-01

There are few data regarding mechanical ventilation and ARDS in the ED. This could be a vital arena for prevention and treatment. This study was a multicenter, observational, prospective, cohort study aimed at analyzing ventilation practices in the ED. The primary outcome was the incidence of ARDS after admission. Multivariable logistic regression was used to determine the predictors of ARDS. We analyzed 219 patients receiving mechanical ventilation to assess ED ventilation practices. Median tidal volume was 7.6 mL/kg predicted body weight (PBW) (interquartile range, 6.9-8.9), with a range of 4.3 to 12.2 mL/kg PBW. Lung-protective ventilation was used in 122 patients (55.7%). The incidence of ARDS after admission from the ED was 14.7%, with a mean onset of 2.3 days. Progression to ARDS was associated with higher illness severity and intubation in the prehospital environment or transferring facility. Of the 15 patients with ARDS in the ED (6.8%), lung-protective ventilation was used in seven (46.7%). Patients who progressed to ARDS experienced greater duration in organ failure and ICU length of stay and higher mortality. Lung-protective ventilation is infrequent in patients receiving mechanical ventilation in the ED, regardless of ARDS status. Progression to ARDS is common after admission, occurs early, and worsens outcome. Patient- and treatment-related factors present in the ED are associated with ARDS. Given the limited treatment options for ARDS, and the early onset after admission from the ED, measures to prevent onset and to mitigate severity should be instituted in the ED. ClinicalTrials.gov; No.: NCT01628523; URL: www.clinicaltrials.gov.

Extracorporeal respiratory support in adult patients

PubMed Central

Romano, Thiago Gomes; Mendes, Pedro Vitale; Park, Marcelo; Costa, Eduardo Leite Vieira

2017-01-01

ABSTRACT In patients with severe respiratory failure, either hypoxemic or hypercapnic, life support with mechanical ventilation alone can be insufficient to meet their needs, especially if one tries to avoid ventilator settings that can cause injury to the lungs. In those patients, extracorporeal membrane oxygenation (ECMO), which is also very effective in removing carbon dioxide from the blood, can provide life support, allowing the application of protective lung ventilation. In this review article, we aim to explore some of the most relevant aspects of using ECMO for respiratory support. We discuss the history of respiratory support using ECMO in adults, as well as the clinical evidence; costs; indications; installation of the equipment; ventilator settings; daily care of the patient and the system; common troubleshooting; weaning; and discontinuation. PMID:28380189

The use of a modified technique to reduce radioactive air contamination in aerosol lung ventilation imaging.

PubMed

Avison, M; Hart, G

2001-06-01

The aim of this study was to reduce airborne contamination resulting from the use of aerosols in lung ventilation scintigraphy. Lung ventilation imaging is frequently performed with 99mTc-diethylenetriaminepentaacetate aerosol (DTPA), derived from a commercial nebuliser. Airborne contamination is a significant problem with this procedure; it results in exposure of staff to radiation and can reduce gamma camera performance when the ventilation is performed in the camera room. We examined the level of airborne contamination resulting from the standard technique with one of the most popular nebuliser kits and tested a modification which significantly reduced airborne contamination. Air contamination was measured while ventilating 122 patients. The modified technique reduced air contamination by a mean value of 64% (p = 0.028) compared with the standard control technique. Additionally, differences in contamination were examined when a mask or mouthpiece was used as well as differences between operators. A simplified method of monitoring air contamination is presented using a commonly available surface contamination monitor. The index so derived was proportional to air contamination (r = 0.88). The problems and regulations associated with airborne contamination are discussed.

Rationale and Description of Right Ventricle-Protective Ventilation in ARDS.

PubMed

Paternot, Alexis; Repessé, Xavier; Vieillard-Baron, Antoine

2016-10-01

Pulmonary vascular dysfunction is associated with ARDS and leads to increased right-ventricular afterload and eventually right-ventricular failure, also called acute cor pulmonale. Interest in acute cor pulmonale and its negative impact on outcome in patients with ARDS has grown in recent years. Right-ventricular function in these patients should be closely monitored, and this is helped by the widespread use of echocardiography in intensive care units. Because mechanical ventilation may worsen right-ventricular failure, the interaction between the lungs and the right ventricle appears to be a key factor in the ventilation strategy. In this review, a rationale for a right ventricle-protective ventilation approach is provided, and such a strategy is described, including the reduction of lung stress (ie, the limitation of plateau pressure and driving pressure), the reduction of PaCO2 , and the improvement of oxygenation. Prone positioning seems to be a crucial part of this strategy by protecting both the lungs and the right ventricle, resulting in increased survival of patients with ARDS. Further studies are required to validate the positive impact on prognosis of right ventricle-protective mechanical ventilation. Copyright © 2016 by Daedalus Enterprises.

Reduction of Endotracheal Tube Connector Dead Space Improves Ventilation: A Bench Test on a Model Lung Simulating an Extremely Low Birth Weight Neonate.

PubMed

Ivanov, Vadim A

2016-02-01

The reduction of instrumental dead space is a recognized approach to preventing ventilation-induced lung injury in premature infants. However, there are no published data regarding the effectiveness of instrumental dead-space reduction in endotracheal tube (ETT) connectors. We tested the impact of the Y-piece/ETT connector pairs with reduced instrumental dead space on CO2 elimination in a model of the premature neonate lung. The standard ETT connector was compared with a low-dead-space ETT connector and with a standard connector equipped with an insert. We compared the setups by measuring the CO2 elimination rate in an artificial lung ventilated via the connectors. The lung was connected to a ventilator via a standard circuit, a 2.5-mm ETT, and one of the connectors under investigation. The ventilator was run in volume-controlled continuous mandatory ventilation mode. The low-dead-space ETT connector/Y-piece and insert-equipped standard connector/Y-piece pairs had instrumental dead space reduced by 36 and 67%, respectively. With set tidal volumes (VT) of 2.5, 5, and 10 mL, in comparison with the standard ETT connector, the low-dead-space connector reduced CO2 elimination time by 4.5% (P < .05), 4.4% (P < .01), and 7.1% (not significant), respectively. The insert-equipped standard connector reduced CO2 elimination time by 13.5, 25.1, and 16.1% (all P < .01). The low-dead-space connector increased inspiratory resistance by 17.8% (P < .01), 9.6% (P < .05), and 5.0% (not significant); the insert-equipped standard connector increased inspiratory resistance by 9.1, 8.4, and 5.9% (all not significant). The low-dead-space connector decreased expiratory resistance by 6.8% (P < .01) and 1.8% (not significant) and increased it by 1.4% (not significant); the insert-equipped standard connector decreased expiratory resistance by 1.5 and 1% and increased it by 1% (all not significant). The low-dead-space connector increased work of breathing by 4.7% (P < .01), 3.8% (P < .01), and 2.5% (not significant); the insert-equipped standard connector increased it by 0.8% (not significant), 2.5% (P < .01), and 2.8% (P < .01). Both methods of instrumental dead-space reduction led to improvements in artificial lung ventilation. Negative effects on resistance and work of breathing appeared minimal. Further testing in vivo should be performed to confirm the lung model results and, if successful, translated into clinical practice. Copyright © 2016 by Daedalus Enterprises.

Assessment of regional emphysema, air-trapping and Xenon-ventilation using dual-energy computed tomography in chronic obstructive pulmonary disease patients.

PubMed

Lee, Sang Min; Seo, Joon Beom; Hwang, Hye Jeon; Kim, Namkug; Oh, Sang Young; Lee, Jae Seung; Lee, Sei Won; Oh, Yeon-Mok; Kim, Tae Hoon

2017-07-01

To compare the parenchymal attenuation change between inspiration/expiration CTs with dynamic ventilation change between xenon wash-in (WI) inspiration and wash-out (WO) expiration CTs. 52 prospectively enrolled COPD patients underwent xenon ventilation dual-energy CT during WI and WO periods and pulmonary function tests (PFTs). The parenchymal attenuation parameters (emphysema index (EI), gas-trapping index (GTI) and air-trapping index (ATI)) and xenon ventilation parameters (xenon in WI (Xe-WI), xenon in WO (Xe-WO) and xenon dynamic (Xe-Dyna)) of whole lung and three divided areas (emphysema, hyperinflation and normal) were calculated on virtual non-contrast images and ventilation images. Pearson correlation, linear regression analysis and one-way ANOVA were performed. EI, GTI and ATI showed a significant correlation with Xe-WI, Xe-WO and Xe-Dyna (EI R = -.744, -.562, -.737; GTI R = -.621, -.442, -.629; ATI R = -.600, -.421, -.610, respectively, p < 0.01). All CT parameters showed significant correlation with PFTs except forced vital capacity (FVC). There was a significant difference in GTI, ATI and Xe-Dyna in each lung area (p < 0.01). The parenchymal attenuation change between inspiration/expiration CTs and xenon dynamic change between xenon WI- and WO-CTs correlate significantly. There are alterations in the dynamics of xenon ventilation between areas of emphysema. • The xenon ventilation change correlates with the parenchymal attenuation change. • The xenon ventilation change shows the difference between three lung areas. • The combination of attenuation and xenon can predict more accurate PFTs.

Lung Mechanics in Marine Mammals

DTIC Science & Technology

2013-09-30

system of anesthetized pinnipeds (Table 1, Fig. 1). In some animals where euthanasia was planned, we managed to measure both lung mechanics in vivo...during spontaneous breathing (dynamic) and mechanical ventilation (static), and the static compliance after euthanasia . Table 1. Number of samples...airway and esophageal pressures during voluntary breathing and mechanical ventilation (Fig. 1). Aim 2: In the second year we also used a fast response

Optimal Delivery of Aerosols to Infants During Mechanical Ventilation

PubMed Central

Azimi, Mandana; Hindle, Michael

2014-01-01

Abstract Purpose: The objective of this study was to determine optimal aerosol delivery conditions for a full-term (3.6 kg) infant receiving invasive mechanical ventilation by evaluating the effects of aerosol particle size, a new wye connector, and timing of aerosol delivery. Methods: In vitro experiments used a vibrating mesh nebulizer and evaluated drug deposition fraction and emitted dose through ventilation circuits containing either a commercial (CM) or new streamlined (SL) wye connector and 3-mm endotracheal tube (ETT) for aerosols with mass median aerodynamic diameters of 880 nm, 1.78 μm, and 4.9 μm. The aerosol was released into the circuit either over the full inhalation cycle (T1 delivery) or over the first half of inhalation (T2 delivery). Validated computational fluid dynamics (CFD) simulations and whole-lung model predictions were used to assess lung deposition and exhaled dose during cyclic ventilation. Results: In vitro experiments at a steady-state tracheal flow rate of 5 L/min resulted in 80–90% transmission of the 880-nm and 1.78-μm aerosols from the ETT. Based on CFD simulations with cyclic ventilation, the SL wye design reduced depositional losses in the wye by a factor of approximately 2–4 and improved lung delivery efficiencies by a factor of approximately 2 compared with the CM device. Delivery of the aerosol over the first half of the inspiratory cycle (T2) reduced exhaled dose from the ventilation circuit by a factor of 4 compared with T1 delivery. Optimal lung deposition was achieved with the SL wye connector and T2 delivery, resulting in 45% and 60% lung deposition for optimal polydisperse (∼1.78 μm) and monodisperse (∼2.5 μm) particle sizes, respectively. Conclusions: Optimization of selected factors and use of a new SL wye connector can substantially increase the lung delivery efficiency of medical aerosols to infants from current values of <1–10% to a range of 45–60%. PMID:24299500

Convexity, Jensen's inequality, and benefits of noisy or biologically variable life support (Keynote Address)

NASA Astrophysics Data System (ADS)

Mutch, W. Alan C.

2005-05-01

Life support with a mechanical ventilator is used to manage patients with a variety of lung diseases including acute respiratory distress syndrome (ARDS). Recently, management of ARDS has concentrated on ventilating at lower airway pressure using lower tidal volume. A large international study demonstrated a 22% reduction in mortality with the low tidal volume approach. The potential advantages of adding physiologic noise with fractal characteristics to the respiratory rate and tidal volume as delivered by a mechanical ventilator are discussed. A so-called biologically variable ventilator (BVV), incorporating such noise, has been developed. Here we show that the benefits of noisy ventilation - at lower tidal volumes - can be deduced from a simple probabilistic result known as Jensen"s Inequality. Using the local convexity of the pressure-volume relationship in the lung we demonstrate that the addition of noise results in higher mean tidal volume or lower mean airway pressure. The consequence is enhanced gas exchange or less stress on the lungs, both clinically desirable. Jensen"s Inequality has important considerations in engineering, information theory and thermodynamics. Here is an example of the concept applied to medicine that may have important considerations for the clinical management of critically ill patients. Life support devices, such as mechanical ventilators, are of vital use in critical care units and operating rooms. These devices usually have monotonous output. Improving mechanical ventilators and other life support devices may be as simple as adding noise to their output signals.

Recruitment Maneuver Does not Increase the Risk of Ventilator Induced Lung Injury

PubMed Central

Akıncı, İbrahim Özkan; Atalan, Korkut; Tuğrul, Simru; Özcan, Perihan Ergin; Yılmazbayhan, Dilek; Kıran, Bayram; Basel, Ahmet; Telci, Lutfi; Çakar, Nahit

2013-01-01

Background: Mechanical ventilation (MV) may induce lung injury. Aims: To assess and evaluate the role of different mechanical ventilation strategies on ventilator-induced lung injury (VILI) in comparison to a strategy which includes recruitment manoeuvre (RM). Study design: Randomized animal experiment. Methods: Thirty male Sprague-Dawley rats were anaesthetised, tracheostomised and divided into 5 groups randomly according to driving pressures; these were mechanically ventilated with following peak alveolar opening (Pao) and positive end-expiratory pressures (PEEP) for 1 hour: Group 15-0: 15 cmH2O Pao and 0 cmH2O PEEP; Group 30-10: 30 cmH2O Pao and 10 cmH2O PEEP; Group 30-5: 30 cmH2O Pao and 5 cmH2O PEEP; Group 30-5&RM: 30 cmH2O Pao and 5 cmH2O PEEP with additional 45 cmH2O CPAP for 30 seconds in every 15 minutes; Group 45-0: 45 cmH2O Pao and 0 cmH2O PEEP Before rats were sacrificed, blood samples were obtained for the evaluation of cytokine and chemokine levels; then, the lungs were subsequently processed for morphologic evaluation. Results: Oxygenation results were similar in all groups; however, the groups were lined as follows according to the increasing severity of morphometric evaluation parameters: Group 15-0: (0±0.009) < Group 30-10: (0±0.14) < Group 30-5&RM: (1±0.12) < Group 30-5: (1±0.16) < Group 45-0: (2±0.16). Besides, inflammatory responses were the lowest in 30-5&RM group compared to all other groups. TNF-α, IL-1β, IL-6, MCP-1 levels were significantly different between group 30-5&RM and group 15-0 vs. group 45-0 in each group. Conclusion: RM with low PEEP reduces the risk of ventilator-induced lung injury with a lower release of systemic inflammatory mediators in response to mechanical ventilation. PMID:25207105

Rationale, study design and analysis plan of the lung imaging morphology for ventilator settings in acute respiratory distress syndrome study (LIVE study): Study protocol for a randomised controlled trial.

PubMed

Jabaudon, Matthieu; Godet, Thomas; Futier, Emmanuel; Bazin, Jean-Étienne; Sapin, Vincent; Roszyk, Laurence; Pereira, Bruno; Constantin, Jean-Michel

2017-10-01

Different acute respiratory distress syndrome (ARDS) phenotypes may explain controversial results in clinical trials. Lung-morphology is one of the ARDS-phenotypes and physiological studies suggest different responses in terms of positive-end-expiratory-pressure (PEEP) and recruitment-manoeuvres (RM) according to loss of aeration. To evaluate whether tailored ventilator regimens may impact ARDS outcomes, our group has designed a randomised-clinical-trial of ventilator settings according to lung morphology in moderate-to-severe ARDS (LIVE study). Patients will be enrolled within the first 12hours of ARDS onset. In both groups, volume-controlled ventilation with low tidal-volumes (Vt) will be used to target a plateau pressure≤30 cmH 2 O. In the control group, the PEEP level and inspired fraction of oxygen (FiO 2 ) will be set using the ARDSNet table; a Vt of 6 mL/kg of predicted body weight (PBW) will be set and prone position (PP) will be applied. In the intervention arm, the ventilator will be set according to lung morphology (focal/non-focal) that will be assessed according to CT-scan±chest x-ray+lung echography. For focal ARDS patients, a Vt of 8 mL/kg PBW will be used along with low PEEP and PP. For non-focal ARDS patients, a Vt of 6 mL/kg PBW will be used with RM and PEEP to reach a plateau pressure≤30 cmH 2 O. The primary outcome is all-cause 90-day mortality and the secondary outcomes are: in-hospital mortality, mortality at day 28, 60, 180 and 365; ventilator-free days at day 30, quality of life at one year; ventilator-associated pneumonia rate; barotrauma; ICU and hospital length of stay. This RCT is registered on Clinicaltrials.gov under identifier NCT02149589. Copyright © 2017 Société française d'anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.

Estimation of Lung Ventilation

NASA Astrophysics Data System (ADS)

Ding, Kai; Cao, Kunlin; Du, Kaifang; Amelon, Ryan; Christensen, Gary E.; Raghavan, Madhavan; Reinhardt, Joseph M.

Since the primary function of the lung is gas exchange, ventilation can be interpreted as an index of lung function in addition to perfusion. Injury and disease processes can alter lung function on a global and/or a local level. MDCT can be used to acquire multiple static breath-hold CT images of the lung taken at different lung volumes, or with proper respiratory control, 4DCT images of the lung reconstructed at different respiratory phases. Image registration can be applied to this data to estimate a deformation field that transforms the lung from one volume configuration to the other. This deformation field can be analyzed to estimate local lung tissue expansion, calculate voxel-by-voxel intensity change, and make biomechanical measurements. The physiologic significance of the registration-based measures of respiratory function can be established by comparing to more conventional measurements, such as nuclear medicine or contrast wash-in/wash-out studies with CT or MR. An important emerging application of these methods is the detection of pulmonary function change in subjects undergoing radiation therapy (RT) for lung cancer. During RT, treatment is commonly limited to sub-therapeutic doses due to unintended toxicity to normal lung tissue. Measurement of pulmonary function may be useful as a planning tool during RT planning, may be useful for tracking the progression of toxicity to nearby normal tissue during RT, and can be used to evaluate the effectiveness of a treatment post-therapy. This chapter reviews the basic measures to estimate regional ventilation from image registration of CT images, the comparison of them to the existing golden standard and the application in radiation therapy.

Emptying patterns of the lung studied by multiple-breath N2 washout

NASA Technical Reports Server (NTRS)

Lewis, S. M.

1978-01-01

Changes in the nitrogen concentration seen during the single-breath nitrogen washout reflect changes in relative flow (ventilation) from units with differing ventilation/volume ratios. The multiple-breath washout provides sufficient data on ventilation for units with varying ventilation/volume ratios to be plotted as a function of the volume expired. Flow from the dead space may also be determined. In young normals the emptying patterns are narrow and unimodal throughout the alveolar plateau with little or no flow from the dead space at the end of the breath. Older normals show more flow from the dead space, particularly toward the end of the breath, and some show a high ventilation/volume ratio mode early in the breath. Patients with obstructive lung disease have a high flow from the dead space which is present throughout the breath. A well ventilated mode at the end of the breath is seen in some obstructed subjects. Patients with cystic fibrosis showed a poorly ventilated mode appearing at the end of the breath as well as a very high dead space.

Tidal volume in acute respiratory distress syndrome: how best to select it.

PubMed

Umbrello, Michele; Marino, Antonella; Chiumello, Davide

2017-07-01

Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO 2 R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented.

Tidal volume in acute respiratory distress syndrome: how best to select it

PubMed Central

Umbrello, Michele; Marino, Antonella

2017-01-01

Mechanical ventilation is the type of organ support most widely provided in the intensive care unit. However, this form of support does not constitute a cure for acute respiratory distress syndrome (ARDS), as it mainly works by buying time for the lungs to heal while contributing to the maintenance of vital gas exchange. Moreover, it can further damage the lung, leading to the development of a particular form of lung injury named ventilator-induced lung injury (VILI). Experimental evidence accumulated over the last 30 years highlighted the factors associated with an injurious form of mechanical ventilation. The present paper illustrates the physiological effects of delivering a tidal volume to the lungs of patients with ARDS, and suggests an approach to tidal volume selection. The relationship between tidal volume and the development of VILI, the so called volotrauma, will be reviewed. The still actual suggestion of a lung-protective ventilatory strategy based on the use of low tidal volumes scaled to the predicted body weight (PBW) will be presented, together with newer strategies such as the use of airway driving pressure as a surrogate for the amount of ventilatable lung tissue or the concept of strain, i.e., the ratio between the tidal volume delivered relative to the resting condition, that is the functional residual capacity (FRC). An ultra-low tidal volume strategy with the use of extracorporeal carbon dioxide removal (ECCO2R) will be presented and discussed. Eventually, the role of other ventilator-related parameters in the generation of VILI will be considered (namely, plateau pressure, airway driving pressure, respiratory rate (RR), inspiratory flow), and the promising unifying framework of mechanical power will be presented. PMID:28828362

Effects of pleural effusion drainage on oxygenation, respiratory mechanics, and hemodynamics in mechanically ventilated patients.

PubMed

Razazi, Keyvan; Thille, Arnaud W; Carteaux, Guillaume; Beji, Olfa; Brun-Buisson, Christian; Brochard, Laurent; Mekontso Dessap, Armand

2014-09-01

In mechanically ventilated patients, the effect of draining pleural effusion on oxygenation is controversial. We investigated the effect of large pleural effusion drainage on oxygenation, respiratory function (including lung volumes), and hemodynamics in mechanically ventilated patients after ultrasound-guided drainage. Arterial blood gases, respiratory mechanics (airway, pleural and transpulmonary pressures, end-expiratory lung volume, respiratory system compliance and resistance), and hemodynamics (blood pressure, heart rate, and cardiac output) were recorded before and at 3 and 24 hours (H24) after pleural drainage. The respiratory settings were kept identical during the study period. The mean volume of effusion drained was 1,579 ± 684 ml at H24. Uncomplicated pneumothorax occurred in two patients. Respiratory mechanics significantly improved after drainage, with a decrease in plateau pressure and a large increase in end-expiratory transpulmonary pressure. Respiratory system compliance, end-expiratory lung volume, and PaO2/FiO2 ratio all improved. Hemodynamics were not influenced by drainage. Improvement in the PaO2/FiO2 ratio from baseline to H24 was positively correlated with the increase in end-expiratory lung volume during the same time frame (r = 0.52, P = 0.033), but not with drained volume. A high value of pleural pressure or a highly negative transpulmonary pressure at baseline predicted limited lung expansion following effusion drainage. A lesser improvement in oxygenation occurred in patients with ARDS. Drainage of large (≥500 ml) pleural effusion in mechanically ventilated patients improves oxygenation and end-expiratory lung volume. Oxygenation improvement correlated with an increase in lung volume and a decrease in transpulmonary pressure, but was less so in patients with ARDS.

Lack of phosphoinositide 3-kinase-gamma attenuates ventilator-induced lung injury.

PubMed

Lionetti, Vincenzo; Lisi, Alberto; Patrucco, Enrico; De Giuli, Paolo; Milazzo, Maria Giovanna; Ceci, Simone; Wymann, Matthias; Lena, Annalisa; Gremigni, Vittorio; Fanelli, Vito; Hirsch, Emilio; Ranieri, V Marco

2006-01-01

G protein-coupled receptors may up-regulate the inflammatory response elicited by ventilator-induced lung injury but also regulate cell survival via protein kinase B (Akt) and extracellular signal regulated kinases 1/2 (ERK1/2). The G protein-sensitive phosphoinositide-3-kinase gamma (PI3Kgamma) regulates several cellular functions including inflammation and cell survival. We explored the role of PI3Kgamma on ventilator-induced lung injury. Prospective, randomized, experimental study. University animal research laboratory. Wild-type (PI3Kgamma), knock-out (PI3Kgamma ), and kinase-dead (PI3Kgamma) mice. Three ventilatory strategies (no stretch, low stretch, high stretch) were studied in an isolated, nonperfused model of acute lung injury (lung lavage) in PI3Kgamma, PI3Kgamma, and PI3Kgamma mice. Reduction in lung compliance, hyaline membrane formation, and epithelial detachment with high stretch were more pronounced in PI3Kgamma than in PI3Kgamma and PI3Kgamma (p < .01). Inflammatory cytokines and IkBalpha phosphorylation with high stretch did not differ among PI3Kgamma, PI3Kgamma, and PI3Kgamma. Apoptotic index (terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling) and caspase-3 (immunohistochemistry) with high stretch were larger (p < .01) in PI3Kgamma and PI3Kgamma than in PI3Kgamma. Electron microscopy showed that high stretch caused apoptotic changes in alveolar cells of PI3Kgamma mice whereas PI3Kgamma mice showed necrosis. Phosphorylation of Akt and ERK1/2 with high stretch was more pronounced in PI3Kgamma than in PI3Kgamma and PI3Kgamma (p < .01). Silencing PI3Kgamma seems to attenuate functional and morphological consequences of ventilator-induced lung injury independently of inhibitory effects on cytokines release but through the enhancement of pulmonary apoptosis.

Simulation of late inspiratory rise in airway pressure during pressure support ventilation.

PubMed

Yu, Chun-Hsiang; Su, Po-Lan; Lin, Wei-Chieh; Lin, Sheng-Hsiang; Chen, Chang-Wen

2015-02-01

Late inspiratory rise in airway pressure (LIRAP, Paw/ΔT) caused by inspiratory muscle relaxation or expiratory muscle contraction is frequently seen during pressure support ventilation (PSV), although the modulating factors are unknown. We investigated the effects of respiratory mechanics (normal, obstructive, restrictive, or mixed), inspiratory effort (-2, -8, or -15 cm H2O), flow cycle criteria (5-40% peak inspiratory flow), and duration of inspiratory muscle relaxation (0.18-0.3 s) on LIRAP during PSV using a lung simulator and 4 types of ventilators. LIRAP occurred with all lung models when inspiratory effort was medium to high and duration of inspiratory muscle relaxation was short. The normal lung model was associated with the fastest LIRAP, whereas the obstructive lung model was associated with the slowest. Unless lung mechanics were normal or mixed, LIRAP was unlikely to occur when inspiratory effort was low. Different ventilators were also associated with differences in LIRAP speed. Except for within the restrictive lung model, changes in flow cycle level did not abolish LIRAP if inspiratory effort was medium to high. Increased duration of inspiratory relaxation also led to the elimination of LIRAP. Simulation of expiratory muscle contraction revealed that LIRAP occurred only when expiratory muscle contraction occurred sometime after the beginning of inspiration. Our simulation study reveals that both respiratory resistance and compliance may affect LIRAP. Except for under restrictive lung conditions, LIRAP is unlikely to be abolished by simply lowering flow cycle criteria when inspiratory effort is strong and relaxation time is rapid. LIRAP may be caused by expiratory muscle contraction when it occurs during inspiration. Copyright © 2015 by Daedalus Enterprises.

DECT Ventilation Imaging

ClinicalTrials.gov

2018-03-21

For Oncologic Patients; Potentially Operable Lung Tumor; With a Recent (Less Than 1 Month) VQ Scan; For Lung Transplant Recipients; Single of Bilateral Lung Transplant; From 5 Months Onwards; With Recent (Less Than 1 Month) Respiratory Functional Explorations

Single-port thoracoscopic surgery for pneumothorax under two-lung ventilation with carbon dioxide insufflation

PubMed Central

Han, Kook Nam; Lee, Hyun Joo; Lee, Dong Kyu; Kim, Heezoo; Lim, Sang Ho; Choi, Young Ho

2016-01-01

Background The development of single-port thoracoscopic surgery and two-lung ventilation reduced the invasiveness of minor thoracic surgery. This study aimed to evaluate the feasibility and safety of single-port thoracoscopic bleb resection for primary spontaneous pneumothorax using two-lung ventilation with carbon dioxide insufflation. Methods Between February 2009 and May 2014, 130 patients underwent single-port thoracoscopic bleb resection under two-lung ventilation with carbon dioxide insufflation. Access was gained using a commercial multiple-access single port through a 2.5-cm incision; carbon dioxide gas was insufflated through a port channel. A 5-mm thoracoscope, articulating endoscopic devices, and flexible endoscopic staplers were introduced through a multiple-access single port for bulla resection. Results The mean time from endotracheal intubation to incision was 29.2±7.8 minutes, the mean operative time was 30.9±8.2 minutes, and the mean total anesthetic time was 75.5±14.4 minutes. There were no anesthesia-related complications or wound problems. The chest drain was removed after a mean of 3.7±1.4 days and patients were discharged without complications 4.8±1.5 days from the operative day. During a mean 7.5±10.1 months of follow-up, there were five recurrences (3.8%) in operated thorax. Conclusions The anesthetic strategy of single-lumen intubation with carbon dioxide gas insufflation can be a safe and feasible option for single-port thoracoscopic bulla resection as it represents the least invasive surgical option with the potential advantages of reducing operative time and one-lung ventilation-related complications without diminishing surgical outcomes. PMID:27293823

Accuracy of near-patient vs. inbuilt spirometry for monitoring tidal volumes in an in-vitro paediatric lung model.

PubMed

Morgenroth, S; Thomas, J; Cannizzaro, V; Weiss, M; Schmidt, A R

2018-03-01

Spirometric monitoring provides precise measurement and delivery of tidal volumes within a narrow range, which is essential for lung-protective strategies that aim to reduce morbidity and mortality in mechanically-ventilated patients. Conventional anaesthesia ventilators include inbuilt spirometry to monitor inspiratory and expiratory tidal volumes. The GE Aisys CS 2 anaesthesia ventilator allows additional near-patient spirometry via a sensor interposed between the proximal end of the tracheal tube and the respiratory tubing. Near-patient and inbuilt spirometry of two different GE Aisys CS 2 anaesthesia ventilators were compared in an in-vitro study. Assessments were made of accuracy and variability in inspiratory and expiratory tidal volume measurements during ventilation of six simulated paediatric lung models using the ASL 5000 test lung. A total of 9240 breaths were recorded and analysed. Differences between inspiratory tidal volumes measured with near-patient and inbuilt spirometry were most significant in the newborn setting (p < 0.001), and became less significant with increasing age and weight. During expiration, tidal volume measurements with near-patient spirometry were consistently more accurate than with inbuilt spirometry for all lung models (p < 0.001). Overall, the variability in measured tidal volumes decreased with increasing tidal volumes, and was smaller with near-patient than with inbuilt spirometry. The variability in measured tidal volumes was higher during expiration, especially with inbuilt spirometry. In conclusion, the present in-vitro study shows that measurements with near-patient spirometry are more accurate and less variable than with inbuilt spirometry. Differences between measurement methods were most significant in the smallest patients. We therefore recommend near-patient spirometry, especially for neonatal and paediatric patients. © 2018 The Association of Anaesthetists of Great Britain and Ireland.

MULTI-FREQUENCY OSCILLATORY VENTILATION IN THE PREMATURE LUNG: EFFECTS ON GAS EXCHANGE, MECHANICS, AND VENTILATION DISTRIBUTION

PubMed Central

Kaczka, David W.; Herrmann, Jacob; Zonneveld, C. Elroy; Tingay, David G.; Lavizzari, Anna; Noble, Peter B.; Pillow, J. Jane

2015-01-01

Background Despite the theoretical benefits of high-frequency oscillatory ventilation (HFOV) in preterm infants, systematic reviews of randomized clinical trials do not confirm improved outcomes. We hypothesized that oscillating a premature lung with multiple frequencies simultaneously would improve gas exchange compared to traditional single-frequency oscillatory ventilation (SFOV). The goal of this study was to develop a novel method for HFOV, termed ‘multi-frequency oscillatory ventilation’ (MFOV), which relies on a broadband flow waveform more suitable for the heterogeneous mechanics of the immature lung. Methods Thirteen intubated preterm lambs were randomized to either SFOV or MFOV for 1 hour, followed by crossover to the alternative regimen for 1 hour. The SFOV waveform consisted of a pure sinusoidal flow at 5 Hz, while the customized MFOV waveform consisted of a 5 Hz fundamental with additional energy at 10 and 15 Hz. Per standardized protocol, mean pressure at airway opening (P̅ao) and inspired O2 fraction were adjusted as needed, and root mean square of the delivered oscillatory volume waveform (Vrms) was adjusted 15-minute intervals. A ventilatory cost function for SFOV and MFOV was defined as VC=(Vrms2PaCO2)Wt−1, where Wt denotes body weight. Results Averaged over all time points, MFOV resulted in significantly lower VC (246.9±6.0 vs. 363.5±15.9 mL2 mmHg kg−1) and P̅ao (12.8±0.3 vs. 14.1±0.5 cmH2O) compared to SFOV, suggesting more efficient gas exchange and enhanced lung recruitment at lower mean airway pressures. Conclusions Oscillation with simultaneous multiple frequencies may be a more efficient ventilator modality in premature lungs compared to traditional single-frequency HFOV. PMID:26495977

Budesonide Attenuates Ventilator-induced Lung Injury in a Rat Model of Inflammatory Acute Respiratory Distress Syndrome.

PubMed

Gao, Wei; Ju, Ying-Nan

2016-05-01

Patients with acute respiratory distress syndrome (ARDS) are particularly susceptible to ventilator-induced lung injury (VILI). This study investigated the effect of budesonide on VILI in a rat model of inflammatory ARDS. Forty eight rats were randomized into three groups (n = 16 each): sham group (S), endotoxin/ventilation group (LV), endotoxin/ventilation/budesonide group (LVB). Rats in the S group received anesthesia only. Rats in the LV and LVB groups received endotoxin to simulate ARDS and were mechanically ventilated for 4 h (tidal volume 30 mL/kg). Rats in the LVB group received budesonide 1 mg, and rats in the LV group received saline in airway. PaO2/FiO2, lung wet-to-dry weight ratios, inflammatory factors in serum and bronchoalveolar lavage fluid (BALF), histopathologic analysis of lung tissue, and survival were examined. PaO2/FiO2 was significantly increased in rats in the LVB group compared to the LV group. Total cell count, macrophages, and neutrophils in BALF, and levels of intercellular adhesion molecule (ICAM)-1, tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-8 in BALF and serum were significantly decreased in rats in the LVB group compared to the LV group, whereas levels of IL-10 in BALF and serum were significantly increased. Histopathological changes of lung injury and apoptosis were reduced, and survival was increased in rats in the LVB group compared to the LV group. Budesonide ameliorated VILI in a rat model of inflammatory ARDS. Copyright © 2016 IMSS. Published by Elsevier Inc. All rights reserved.

Pulmonary NO and C18O2 uptake during pressure-induced lung expansion in rabbits.

PubMed

Heller, Hartmut; Schuster, Klaus-Dieter

2007-01-01

In artificially ventilated animals we investigated the dependence of the pulmonary diffusing capacities of nitric oxide (NO) and doubly 18O-labeled carbon dioxide (DLNO, DLC18O2) on lung expansion with respect to ventilator-driven increases in intrapulmonary pressure. For this purpose we applied computerized single-breath experiments to 11 anesthetized paralyzed rabbits (weight 2.8-3.8 kg) at various alveolar volumes (45-72 ml) by studying the almost entire inspiratory limb of the respective pressure/volume curves (intrapulmonary pressure: 6-27 cmH2O). The animals were ventilated with room air, employing a computerized ventilatory servo-system that we designed to maintain mechanical ventilation and to execute the particular lung function tests automatically. Each single-breath maneuver was started from residual volume (13.5+/-2 ml, mean+/-SD) by inflating the rabbit lungs with 35-55 ml indicator gas mixture containing 0.05% NO in N2 or 0.9% C18O2 in N2. Alveolar partial pressures of NO and C18O2 were measured by respiratory mass spectrometry. Values of DLNO and DLC18O2 ranged between 1.55 and 2.49 ml/(mmHg min) and 11.7 and 16.6 ml/(mmHg min), respectively. Linear regression analyses yielded a significant increase in DLNO with simultaneous increase in alveolar volume (P<0.005) and intrapulmonary pressure (P<0.023) whereas DLC18O2 was not improved. Our results suggest that the ventilator-driven lung expansion impaired the C18O2 blood uptake conductance, finally compensating for the beneficial effect of the increase in alveolar volume on DLC18O2 values.

Interactive simulation system for artificial ventilation on the internet: virtual ventilator.

PubMed

Takeuchi, Akihiro; Abe, Tadashi; Hirose, Minoru; Kamioka, Koichi; Hamada, Atsushi; Ikeda, Noriaki

2004-12-01

To develop an interactive simulation system "virtual ventilator" that demonstrates the dynamics of pressure and flow in the respiratory system under the combination of spontaneous breathing, ventilation modes, and ventilator options. The simulation system was designed to be used by unexperienced health care professionals as a self-training tool. The system consists of a simulation controller and three modules: respiratory, spontaneous breath, and ventilator. The respiratory module models the respiratory system by three resistances representing the main airway, the right and left lungs, and two compliances also representing the right and left lungs. The spontaneous breath module generates inspiratory negative pressure produced by a patient. The ventilator module generates driving force of pressure or flow according to the combination of the ventilation mode and options. These forces are given to the respiratory module through the simulation controller. The simulation system was developed using HTML, VBScript (3000 lines, 100 kB) and ActiveX control (120 kB), and runs on Internet Explorer (5.5 or higher). The spontaneous breath is defined by a frequency, amplitude and inspiratory patterns in the spontaneous breath module. The user can construct a ventilation mode by setting a control variable, phase variables (trigger, limit, and cycle), and options. Available ventilation modes are: controlled mechanical ventilation (CMV), continuous positive airway pressure, synchronized intermittent mandatory ventilation (SIMV), pressure support ventilation (PSV), SIMV + PSV, pressure-controlled ventilation (PCV), pressure-regulated volume control (PRVC), proportional assisted ventilation, mandatory minute ventilation (MMV), bilevel positive airway pressure (BiPAP). The simulation system demonstrates in a graph and animation the airway pressure, flow, and volume of the respiratory system during mechanical ventilation both with and without spontaneous breathing. We developed a web application that demonstrated the respiratory mechanics and the basic theory of ventilation mode.

A model of neonatal tidal liquid ventilation mechanics.

PubMed

Costantino, M L; Fiore, G B

2001-09-01

Tidal liquid ventilation (TLV) with perfluorocarbons (PFC) has been proposed to treat surfactant-deficient lungs of preterm neonates, since it may prevent pulmonary instability by abating saccular surface tension. With a previous model describing gas exchange, we showed that ventilator settings are crucial for CO(2) scavenging during neonatal TLV. The present work is focused on some mechanical aspects of neonatal TLV that were hardly studied, i.e. the distribution of mechanical loads in the lungs, which is expected to differ substantially from gas ventilation. A new computational model is presented, describing pulmonary PFC hydrodynamics, where viscous losses, kinetic energy changes and lung compliance are accounted for. The model was implemented in a software package (LVMech) aimed at calculating pressures (and approximately estimate shear stresses) within the bronchial tree at different ventilator regimes. Simulations were run taking the previous model's outcomes into account. Results show that the pressure decrease due to high saccular compliance may compensate for the increased pressure drops due to PFC viscosity, and keep airway pressure low. Saccules are exposed to pressures remarkably different from those at the airway opening; during expiration negative pressures, which may cause airway collapse, are moderate and appear in the upper airways only. Delivering the fluid with a slightly smoothed square flow wave is convenient with respect to a sine wave. The use of LVMech allows to familiarize with LV treatment management taking the lungs' mechanical load into account, consistently with a proper respiratory support.

A Four-Dimensional Computed Tomography Comparison of Healthy vs. Asthmatic Human Lungs

PubMed Central

Jahani, Nariman; Choi, Sanghun; Choi, Jiwoong; Haghighi, Babak; Hoffman, Eric A.; Comellas, Alejandro P.; Kline, Joel N.; Lin, Ching-Long

2017-01-01

The purpose of this study was to explore new insights in non-linearity, hysteresis and ventilation heterogeneity of asthmatic human lungs using four-dimensional computed tomography (4D-CT) image data acquired during tidal breathing. Volumetric image data were acquired for 5 non-severe and one severe asthmatic volunteers. Besides 4D-CT image data, function residual capacity and total lung capacity image data during breath-hold were acquired for comparison with dynamic scans. Quantitative results were compared with the previously reported analysis of five healthy human lungs. Using an image registration technique, local variables such as regional ventilation and anisotropic deformation index (ADI) were estimated. Regional ventilation characteristics of non-severe asthmatic subjects were similar to those of healthy subjects, but different from the severe asthmatic subject. Lobar airflow fractions were also well correlated between static and dynamic scans (R2 > 0.84). However, local ventilation heterogeneity significantly increased during tidal breathing in both healthy and asthmatic subjects relative to that of breath-hold perhaps because of airway resistance present only in dynamic breathing. ADI was used to quantify non-linearity and hysteresis of lung motion during tidal breathing. Nonlinearity was greater on inhalation than exhalation among all subjects. However, exhalation nonlinearity among asthmatic subjects was greater than healthy subjects and the difference diminished during inhalation. An increase of non-linearity during exhalation in asthmatic subjects accounted for lower hysteresis relative to that of healthy ones. Thus, assessment of nonlinearity differences between healthy and asthmatic lungs during exhalation may provide quantitative metrics for subject identification and outcome assessment of new interventions. PMID:28372795

Measurement of changes in respiratory mechanics during partial liquid ventilation using jet pulses.

PubMed

Schmalisch, Gerd; Schmidt, Mario; Proquitté, Hans; Foitzik, Bertram; Rüdiger, Mario; Wauer, Roland R

2003-05-01

To compare the changes in respiratory mechanics within the breathing cycle in healthy lungs between gas ventilation and partial liquid ventilation using a special forced-oscillation technique. Prospective animal trial. Animal laboratory in a university setting. A total of 12 newborn piglets (age, <12 hrs; mean weight, 725 g). After intubation and instrumentation, lung mechanics of the anesthetized piglets were measured by forced-oscillation technique at the end of inspiration and the end of expiration. The measurements were performed during gas ventilation and 80 mins after instillation of 30 mL/kg perfluorocarbon PF 5080. Brief flow pulses (width, 10 msec; peak flow, 16 L/min) were generated by a jet generator to measure the end-inspiratory and the end-expiratory respiratory input impedance in the frequency range of 4-32 Hz. The mechanical variables resistance, inertance, and compliance were determined by model fitting, using the method of least squares. At least in the lower frequency range, respiratory mechanics could be described adequately by an RIC single-compartment model in all piglets. During gas ventilation, the respiratory variables resistance and inertance did not differ significantly between end-inspiratory and end-expiratory measurements (mean [sd]: 4.2 [0.7] vs. 4.1 [0.6] kPa x L(-1) x sec, 30.0 [3.2] vs. 30.7 [3.1] Pa x L(-1) x sec2, respectively), whereas compliance decreased during inspiration from 14.8 (2.0) to 10.2 (2.4) mL x kPa(-1) x kg(-1) due to a slight lung overdistension. During partial liquid ventilation, the end-inspiratory respiratory mechanics was not different from the end-inspiratory respiratory mechanics measured during gas ventilation. However, in contrast to gas ventilation during partial liquid ventilation, compliance rose from 8.2 (1.0) to 13.0 (3.0) mL x kPa(-1) x kg(-1) during inspiration. During expiration, when perfluorocarbon came into the upper airways, both resistance and inertance increased considerably (mean with 95% confidence interval) by 34.3% (23.1%-45.8%) and 104.1% (96.0%-112.1%), respectively. The changes in the respiratory mechanics within the breathing cycle are considerably higher during partial liquid ventilation compared with gas ventilation. This dependence of lung mechanics from the pulmonary gas volume hampers the comparability of dynamic measurements during partial liquid ventilation, and the magnitude of these changes cannot be detected by conventional respiratory-mechanical analysis using time-averaged variables.

Intrabullous ventilation in pulmonary emphysema: assessment with dynamic xenon-133 gas SPECT.

PubMed

Suga, Kazuyoshi; Iwanaga, Hideyuki; Tokuda, Osamu; Okada, Munemasa; Matsunaga, Naofumi

2012-04-01

Intrabullous ventilation in patients with pulmonary emphysema (PE) was cross-sectionally evaluated using dynamic xenon-133 gas single photon emission computed tomography (SPECT). Fifty-two patients with PE with a total of 109 bullae of more than 4 cm in maximum diameter underwent xenon-133 gas SPECT. The real xenon-133 gas half-clearance time (T1/2) at each bulla was compared with that at the surrounding lung in the same lobe. The emphysema subtype of the surrounding lung was classified into centrilobular, panlobular, and paraseptal on computed tomography (CT). All bullae except for one in all patients showed xenon-133 gas wash-in. Of the 108 bullae with wash-in, 95 (87.9%) bullae in 46 (88%) patients showed marked xenon-133 gas retention with a T1/2 beyond 110 s (mean: 184 s ± 91). The surrounding lungs of these bullae also showed marked retention with a T1/2 of greater than 100 s (mean: 174 s ± 82), and the majority (N=92, 96.8%) were centrilobular or panlobular on CT. The remaining 13 (12.0%) bullae in six (11%) patients showed minimal retention with a T1/2 of less than 80 s (mean: 62 s ± 11), regardless of no significant difference in size compared with the bullae with marked retention. All the surrounding lungs of these bullae except for one also showed minimal retention with a T1/2 of less than 70 s (mean: 60 s ± 18), which was significantly less compared with that of the bullae with marked retention (P<0.0001), and the majority (N=11, 84.6%) were paraseptal with or without an interstitially fibrotic change and predominantly located at the lower lung lobe on CT. The T1/2 of the 108 bullae with xenon-133 gas wash-in was significantly correlated with that of the surrounding lungs (r=0.884, P<0.0001). Intrabullous ventilation in patients with PE appears to depend on the ventilation status of the surrounding lung, and bullae with the surrounding lungs of paraseptal-type emphysema tend to show minimal air trapping. Xenon-133 gas SPECT is useful for assessment of the interaction between intrabullous and surrounding lung's ventilation, which is difficult on CT.

Ventilation and cardiac related impedance changes in children undergoing corrective open heart surgery.

PubMed

Schibler, Andreas; Pham, Trang M T; Moray, Amol A; Stocker, Christian

2013-10-01

Electrical impedance tomography (EIT) can determine ventilation and perfusion relationship. Most of the data obtained so far originates from experimental settings and in healthy subjects. The aim of this study was to demonstrate that EIT measures the perioperative changes in pulmonary blood flow after repair of a ventricular septum defect in children with haemodynamic relevant septal defects undergoing open heart surgery. In a 19 bed intensive care unit in a tertiary children's hospital ventilation and cardiac related impedance changes were measured using EIT before and after surgery in 18 spontaneously breathing patients. The EIT signals were either filtered for ventilation (ΔZV) or for cardiac (ΔZQ) related impedance changes. Impedance signals were then normalized (normΔZV, normΔZQ) for calculation of the global and regional impedance related ventilation perfusion relationship (normΔZV/normΔZQ). We observed a trend towards increased normΔZV in all lung regions, a significantly decreased normΔZQ in the global and anterior, but not the posterior lung region. The normΔZV/normΔZQ was significantly increased in the global and anterior lung region. Our study qualitatively validates our previously published modified EIT filtration technique in the clinical setting of young children with significant left-to-right shunt undergoing corrective open heart surgery, where perioperative assessment of the ventilation perfusion relation is of high clinical relevance.

Lower tidal volume strategy (≈3 ml/kg) combined with extracorporeal CO2 removal versus 'conventional' protective ventilation (6 ml/kg) in severe ARDS: the prospective randomized Xtravent-study.

PubMed

Bein, Thomas; Weber-Carstens, Steffen; Goldmann, Anton; Müller, Thomas; Staudinger, Thomas; Brederlau, Jörg; Muellenbach, Ralf; Dembinski, Rolf; Graf, Bernhard M; Wewalka, Marlene; Philipp, Alois; Wernecke, Klaus-Dieter; Lubnow, Matthias; Slutsky, Arthur S

2013-05-01

Acute respiratory distress syndrome is characterized by damage to the lung caused by various insults, including ventilation itself, and tidal hyperinflation can lead to ventilator induced lung injury (VILI). We investigated the effects of a low tidal volume (V(T)) strategy (V(T) ≈ 3 ml/kg/predicted body weight [PBW]) using pumpless extracorporeal lung assist in established ARDS. Seventy-nine patients were enrolled after a 'stabilization period' (24 h with optimized therapy and high PEEP). They were randomly assigned to receive a low V(T) ventilation (≈3 ml/kg) combined with extracorporeal CO2 elimination, or to a ARDSNet strategy (≈6 ml/kg) without the extracorporeal device. The primary outcome was the 28-days and 60-days ventilator-free days (VFD). Secondary outcome parameters were respiratory mechanics, gas exchange, analgesic/sedation use, complications and hospital mortality. Ventilation with very low V(T)'s was easy to implement with extracorporeal CO2-removal. VFD's within 60 days were not different between the study group (33.2 ± 20) and the control group (29.2 ± 21, p = 0.469), but in more hypoxemic patients (PaO2/FIO2 ≤150) a post hoc analysis demonstrated significant improved VFD-60 in study patients (40.9 ± 12.8) compared to control (28.2 ± 16.4, p = 0.033). The mortality rate was low (16.5%) and did not differ between groups. The use of very low V(T) combined with extracorporeal CO2 removal has the potential to further reduce VILI compared with a 'normal' lung protective management. Whether this strategy will improve survival in ARDS patients remains to be determined (Clinical trials NCT 00538928).

Quantification and visualization of relative local ventilation on dynamic chest radiographs

NASA Astrophysics Data System (ADS)

Tanaka, Rie; Sanada, Shigeru; Okazaki, Nobuo; Kobayashi, Takeshi; Nakayama, Kazuya; Matsui, Takeshi; Hayashi, Norio; Matsui, Osamu

2006-03-01

Recently-developed dynamic flat-panel detector (FPD) with a large field of view is possible to obtain breathing chest radiographs, which provide respiratory kinetics information. This study was performed to investigate the ability of dynamic chest radiography using FPD to quantify relative ventilation according to respiratory physiology. We also reported the results of primary clinical study and described the possibility of clinical use of our method. Dynamic chest radiographs of 12 subjects involving abnormal subjects during respiration were obtained using a modified FPD system (30 frames in 10 seconds). Imaging was performed in three different positions (standing, and right and left decubitus positions) to change the distribution of local ventilation by changing the lung's own gravity in each area. The distance from the lung apex to the diaphragm (abbr. DLD) was measured by the edge detection technique for use as an index of respiratory phase. We measured pixel values in each lung area and calculated correlation coefficients with DLD. Differences in the pixel values between the maximum inspiratory and expiratory frame were calculated, and the trend of distribution was evaluated by two-way analysis of variance. Pixel value in each lung area was strongly associated with respiratory phase and its time variation and distribution were consistent with known properties in respiratory physiology. Dynamic chest radiography using FPD combined with our computerized methods was capable of quantifying relative amount of ventilation during respiration, and of detecting regional differences in ventilation. In the subjects with emphysema, areas with decreased respiratory changes in pixel value are consisted with the areas with air trapping. This method is expected to be a useful novel diagnostic imaging method for supporting diagnosis and follow-up of pulmonary disease, which presents with abnormalities in local ventilation.

Hyperpolarized gas diffusion MRI for the study of atelectasis and acute respiratory distress syndrome.

PubMed

Cereda, Maurizio; Xin, Yi; Kadlecek, Stephen; Hamedani, Hooman; Rajaei, Jennia; Clapp, Justin; Rizi, Rahim R

2014-12-01

Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury, which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of computed tomography, positron emission tomography, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized (HP) gas MRI--a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces--is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of (3) He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces, (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces, and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation. Copyright © 2014 John Wiley & Sons, Ltd.

Hyperpolarized Gas Diffusion MRI for the Study of Atelectasis and Acute Respiratory Distress Syndrome

PubMed Central

Cereda, Maurizio; Xin, Yi; Kadlecek, Stephen; Hamedani, Hooman; Rajaei, Jennia; Clapp, Justin; Rizi, Rahim R.

2014-01-01

Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury (VALI), which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of CT, PET, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized gas magnetic resonance imaging (HP MRI)—a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces—is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of 3He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces; (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces; and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation. PMID:24920074

Comparison between effects of pressure support and pressure-controlled ventilation on lung and diaphragmatic damage in experimental emphysema.

PubMed

Padilha, Gisele de A; Horta, Lucas F B; Moraes, Lillian; Braga, Cassia L; Oliveira, Milena V; Santos, Cíntia L; Ramos, Isalira P; Morales, Marcelo M; Capelozzi, Vera Luiza; Goldenberg, Regina C S; de Abreu, Marcelo Gama; Pelosi, Paolo; Silva, Pedro L; Rocco, Patricia R M

2016-12-01

In patients with emphysema, invasive mechanical ventilation settings should be adjusted to minimize hyperinflation while reducing respiratory effort and providing adequate gas exchange. We evaluated the impact of pressure-controlled ventilation (PCV) and pressure support ventilation (PSV) on pulmonary and diaphragmatic damage, as well as cardiac function, in experimental emphysema. Emphysema was induced by intratracheal instillation of porcine pancreatic elastase in Wistar rats, once weekly for 4 weeks. Control animals received saline under the same protocol. Eight weeks after first instillation, control and emphysema rats were randomly assigned to PCV (n = 6/each) or PSV (n = 6/each) under protective tidal volume (6 ml/kg) for 4 h. Non-ventilated control and emphysema animals (n = 6/group) were used to characterize the model and for molecular biology analysis. Cardiorespiratory function, lung histology, diaphragm ultrastructure alterations, extracellular matrix organization, diaphragmatic proteolysis, and biological markers associated with pulmonary inflammation, alveolar stretch, and epithelial and endothelial cell damage were assessed. Emphysema animals exhibited cardiorespiratory changes that resemble human emphysema, such as increased areas of lung hyperinflation, pulmonary amphiregulin expression, and diaphragmatic injury. In emphysema animals, PSV compared to PCV yielded: no changes in gas exchange; decreased mean transpulmonary pressure (Pmean,L), ratio between inspiratory and total time (Ti/Ttot), lung hyperinflation, and amphiregulin expression in lung; increased ratio of pulmonary artery acceleration time to pulmonary artery ejection time, suggesting reduced right ventricular afterload; and increased ultrastructural damage to the diaphragm. Amphiregulin correlated with Pmean,L (r = 0.99, p < 0.0001) and hyperinflation (r = 0.70, p = 0.043), whereas Ti/Ttot correlated with hyperinflation (r = 0.81, p = 0.002) and Pmean,L (r = 0.60, p = 0.04). In the model of elastase-induced emphysema used herein, PSV reduced lung damage and improved cardiac function when compared to PCV, but worsened diaphragmatic injury.

Coupling of EIT with computational lung modeling for predicting patient-specific ventilatory responses.

PubMed

Roth, Christian J; Becher, Tobias; Frerichs, Inéz; Weiler, Norbert; Wall, Wolfgang A

2017-04-01

Providing optimal personalized mechanical ventilation for patients with acute or chronic respiratory failure is still a challenge within a clinical setting for each case anew. In this article, we integrate electrical impedance tomography (EIT) monitoring into a powerful patient-specific computational lung model to create an approach for personalizing protective ventilatory treatment. The underlying computational lung model is based on a single computed tomography scan and able to predict global airflow quantities, as well as local tissue aeration and strains for any ventilation maneuver. For validation, a novel "virtual EIT" module is added to our computational lung model, allowing to simulate EIT images based on the patient's thorax geometry and the results of our numerically predicted tissue aeration. Clinically measured EIT images are not used to calibrate the computational model. Thus they provide an independent method to validate the computational predictions at high temporal resolution. The performance of this coupling approach has been tested in an example patient with acute respiratory distress syndrome. The method shows good agreement between computationally predicted and clinically measured airflow data and EIT images. These results imply that the proposed framework can be used for numerical prediction of patient-specific responses to certain therapeutic measures before applying them to an actual patient. In the long run, definition of patient-specific optimal ventilation protocols might be assisted by computational modeling. NEW & NOTEWORTHY In this work, we present a patient-specific computational lung model that is able to predict global and local ventilatory quantities for a given patient and any selected ventilation protocol. For the first time, such a predictive lung model is equipped with a virtual electrical impedance tomography module allowing real-time validation of the computed results with the patient measurements. First promising results obtained in an acute respiratory distress syndrome patient show the potential of this approach for personalized computationally guided optimization of mechanical ventilation in future. Copyright © 2017 the American Physiological Society.

The gravitational distribution of ventilation-perfusion ratio is more uniform in prone than supine posture in the normal human lung

PubMed Central

Sá, Rui Carlos; Theilmann, Rebecca J.; Buxton, Richard B.; Prisk, G. Kim; Hopkins, Susan R.

2013-01-01

The gravitational gradient of intrapleural pressure is suggested to be less in prone posture than supine. Thus the gravitational distribution of ventilation is expected to be more uniform prone, potentially affecting regional ventilation-perfusion (V̇a/Q̇) ratio. Using a novel functional lung magnetic resonance imaging technique to measure regional V̇a/Q̇ ratio, the gravitational gradients in proton density, ventilation, perfusion, and V̇a/Q̇ ratio were measured in prone and supine posture. Data were acquired in seven healthy subjects in a single sagittal slice of the right lung at functional residual capacity. Regional specific ventilation images quantified using specific ventilation imaging and proton density images obtained using a fast gradient-echo sequence were registered and smoothed to calculate regional alveolar ventilation. Perfusion was measured using arterial spin labeling. Ventilation (ml·min−1·ml−1) images were combined on a voxel-by-voxel basis with smoothed perfusion (ml·min−1·ml−1) images to obtain regional V̇a/Q̇ ratio. Data were averaged for voxels within 1-cm gravitational planes, starting from the most gravitationally dependent lung. The slope of the relationship between alveolar ventilation and vertical height was less prone than supine (−0.17 ± 0.10 ml·min−1·ml−1·cm−1 supine, −0.040 ± 0.03 prone ml·min−1·ml−1·cm−1, P = 0.02) as was the slope of the perfusion-height relationship (−0.14 ± 0.05 ml·min−1·ml−1·cm−1 supine, −0.08 ± 0.09 prone ml·min−1·ml−1·cm−1, P = 0.02). There was a significant gravitational gradient in V̇a/Q̇ ratio in both postures (P < 0.05) that was less in prone (0.09 ± 0.08 cm−1 supine, 0.04 ± 0.03 cm−1 prone, P = 0.04). The gravitational gradients in ventilation, perfusion, and regional V̇a/Q̇ ratio were greater supine than prone, suggesting an interplay between thoracic cavity configuration, airway and vascular tree anatomy, and the effects of gravity on V̇a/Q̇ matching. PMID:23620488

Continuous distending pressure effects on variables contributing to oxygenation in healthy and ARDS model pigs during HFOV

NASA Astrophysics Data System (ADS)

Laviola, Marianna; Hajny, Ondrej; Roubik, Karel

2014-10-01

High frequency oscillatory ventilation (HFOV) is an alternative mode of mechanical ventilation. HFOV has been shown to provide adequate ventilation and oxygenation in acute respiratory distress syndrome (ARDS) patients and may represent an effective lung-protective ventilation in patients where conventional ventilation is failing. The aim of this study is to evaluate effects of continuous distending pressure (CDP) on variables that contribute to the oxygenation in healthy and ARDS lung model pigs. Methods. In order to simulate a lung disease, lung injury was induced by lavage with normal saline with detergent in three pigs. HFOV ventilation was applied before and after the lung lavage. CDP was stepwise increased by 2 cmH2O, until the maximum CDP (before the lung lavage 32 cmH2O and after the lung lavage 42 cmH2O) and then it was stepwise decreased by 2 cmH2O to the initial value. In this paper we analyzed the following parameters acquired during our experiments: partial pressure of oxygen in arterial blood (PaO2), cardiac output (CO) and mixed venous blood oxygen saturation (SvO2). In order to find how both PaO2 and CO affected SvO2 during the increase of CDP before and after lavage, a nonlinear regression fitting of the response in SvO2 on the predictors (PaO2 and CO) was implemented. Results. Before the lavage, with increasing of CDP, PaO2 remained constant, CO strongly decreased and SvO2 slightly decreased. After the lavage, with increasing of CDP, PaO2 strongly increased, CO decreased and SvO2 increased. So, development of SvO2 followed the PaO2 and CO trends. Changes in PaO2 and CO occur at decisive CDP step and it was much higher after the lung lavage compared to the healthy lungs. The implemented nonlinear model gives a good goodness of fitting in all three pigs. The values of PaO2 and CO estimated coefficients changed at the same decisive step of CDP identified by the trends. Also the algorithm identified a CDP step much higher after the lung lavage. Conclusions. The novelty of this study consists of the implementing of a model that allows to predict how PaO2 and CO affect SvO2. It is possible to identify a certain level of CDP (higher in ARDS model pigs) at which the contribution of PaO2 and CO to SvO2 course changes their weights. Above this value, PaO2 plays a major role in SvO2 developments. This is in concordance with the clinical experience that HFOV is suitable for patient with more severe lung diseases when much higher CDP levels are required to assure an adequate oxygenation.

Lung Transplant

MedlinePlus

... in the hospital's intensive care unit (ICU). A mechanical ventilator will help you breathe for a few ... condition improves, you'll no longer need the mechanical ventilator, and you'll be moved out of ...

21 CFR 868.5905 - Noncontinuous ventilator (IPPB).

Code of Federal Regulations, 2010 CFR

2010-04-01

... (IPPB). (a) Identification. A noncontinuous ventilator (intermittent positive pressure breathing-IPPB) is a device intended to deliver intermittently an aerosol to a patient's lungs or to assist a patient...

Nebulized heparin for patients under mechanical ventilation: an individual patient data meta-analysis.

PubMed

Glas, Gerie J; Serpa Neto, Ary; Horn, Janneke; Cochran, Amalia; Dixon, Barry; Elamin, Elamin M; Faraklas, Iris; Dissanaike, Sharmila; Miller, Andrew C; Schultz, Marcus J

2016-12-01

Pulmonary coagulopathy is a characteristic feature of lung injury including ventilator-induced lung injury. The aim of this individual patient data meta-analysis is to assess the effects of nebulized anticoagulants on outcome of ventilated intensive care unit (ICU) patients. A systematic search of PubMed (1966-2014), Scopus, EMBASE, and Web of Science was conducted to identify relevant publications. Studies evaluating nebulization of anticoagulants in ventilated patients were screened for inclusion, and corresponding authors of included studies were contacted to provide individual patient data. The primary endpoint was the number of ventilator-free days and alive at day 28. Secondary endpoints included hospital mortality, ICU- and hospital-free days at day 28, and lung injury scores at day seven. We constructed a propensity score-matched cohort for comparisons between patients treated with nebulized anticoagulants and controls. Data from five studies (one randomized controlled trial, one open label study, and three studies using historical controls) were included in the meta-analysis, compassing 286 patients. In all studies unfractionated heparin was used as anticoagulant. The number of ventilator-free days and alive at day 28 was higher in patients treated with nebulized heparin compared to patients in the control group (14 [IQR 0-23] vs. 6 [IQR 0-22]), though the difference did not reach statistical significance (P = 0.459). The number of ICU-free days and alive at day 28 was significantly higher, and the lung injury scores at day seven were significantly lower in patients treated with nebulized heparin. In the propensity score-matched analysis, there were no differences in any of the endpoints. This individual patient data meta-analysis provides no convincing evidence for benefit of heparin nebulization in intubated and ventilated ICU patients. The small patient numbers and methodological shortcomings of included studies underline the need for high-quality well-powered randomized controlled trials.

Distributed augmented reality with 3-D lung dynamics--a planning tool concept.

PubMed

Hamza-Lup, Felix G; Santhanam, Anand P; Imielińska, Celina; Meeks, Sanford L; Rolland, Jannick P

2007-01-01

Augmented reality (AR) systems add visual information to the world by using advanced display techniques. The advances in miniaturization and reduced hardware costs make some of these systems feasible for applications in a wide set of fields. We present a potential component of the cyber infrastructure for the operating room of the future: a distributed AR-based software-hardware system that allows real-time visualization of three-dimensional (3-D) lung dynamics superimposed directly on the patient's body. Several emergency events (e.g., closed and tension pneumothorax) and surgical procedures related to lung (e.g., lung transplantation, lung volume reduction surgery, surgical treatment of lung infections, lung cancer surgery) could benefit from the proposed prototype.

Daytime Mouthpiece for Continuous Noninvasive Ventilation in Individuals With Amyotrophic Lateral Sclerosis.

PubMed

Bédard, Marie-Eve; McKim, Douglas A

2016-10-01

Noninvasive ventilation (NIV) is commonly used to provide ventilatory support for individuals with amyotrophic lateral sclerosis (ALS). Once 24-h ventilation is required, the decision between invasive tracheostomy ventilation and palliation is often faced. This study describes the use and outcomes of daytime mouthpiece ventilation added to nighttime mask ventilation for continuous NIV in subjects with ALS as an effective alternative. This was a retrospective study of 39 subjects with ALS using daytime mouthpiece ventilation over a 17-y period. Thirty-one subjects were successful with mouthpiece ventilation, 2 were excluded, 2 stopped because of lack of motivation, and 4 with bulbar subscores of the Revised Amyotrophic Lateral Sclerosis Functional Rating Scale (b-ALSFRS-R) between 0 and 3 physically failed to use it consistently. No subject in the successful group had a b-ALSFRS-R score of <6. Thirty of the successful subjects were able to generate a maximum insufflation capacity - vital capacity difference with lung volume recruitment. The median (range) survival to tracheostomy or death from initiation of nocturnal NIV and mouthpiece ventilation were 648 (176-2,188) and 286 (41-1,769) d, respectively. Peak cough flow with lung-volume recruitment >180 L/min at initiation of mouthpiece ventilation was associated with a longer survival (637 ± 468 vs 240 ± 158 d (P = .01). Mouthpiece ventilation provides effective ventilation and prolonged survival for individuals with ALS requiring full-time ventilatory support and maintaining adequate bulbar function. Copyright © 2016 by Daedalus Enterprises.

NEUTROPHIL DEPLETION ATTENUATES INTERLEUKIN-8 PRODUCTION IN MILD-OVERSTRETCHED VENTILATED NORMAL RABBIT LUNG

EPA Science Inventory

OBJECTIVE: Acute lung injury induced by lung overstretch is associated with neutrophil influx, but the pathogenic role of neutrophils in overstretch-induced lung injury remains unclear. DESIGN: To assess the contribution of neutrophils, we compared the effects of noninjurious lar...

Unilateral pleural effusion in an animal model: evaluation of lung function with EBCT

NASA Astrophysics Data System (ADS)

Recheis, Wolfgang A.; Pallwein, Leo; Soegner, Peter; Faschingbauer, Ralph; Schmidbauer, Georg; Kleinsasser, Axel; Loeckinger, Alexander; Hoermann, Christoph; zur Nedden, Dieter

2003-05-01

The purpsoe was to evaluate the influence of a right-sided pleural effusion on the lung aeration dynamics in the respiratory cycle during pressure controlled ventilation. Pleural effusion was simulated by infusion of 3% gelatin into the pleural cavity in steps of 300ml totaling 1200ml in four anesthetized pigs. After each step, volume scans and respirator gated 50ms scans at a constant table position (carina niveau) were taken. The dynamic changes of the previously defined air-tissue ratios (in steps of 100HU) were evaluated in three separate regions of left and right lung: a ventral, an intermediate and a dorsal area. The affected side revealed dramatic alveolar collapse. There was a shift of the lung density to higher air-tissue ratios (+200HU) but showing the same air-tissue ratio dynamics. A slight lateral shift of 32mm (+/-14mm) the mediastinum was measured. The unaffected side showed no increase in the air-tissue ratios caused by hyperinflation but an increase of density due to mediastinal shift. Air-tissue ratio dynamics remained unchanged on the unaffected side compared to baseline measurements. We visualized the ventilation mismatch caused by pleural effusion. The contra-lateral lung is not affected by unilateral pleural effusion. Pressure controlled ventilation prevents hyper-inflation of non-dependent lung areas.

Paclitaxel-induced lung injury and its amelioration by parecoxib sodium.

PubMed

Liu, Wen-jie; Zhong, Zhong-jian; Cao, Long-hui; Li, Hui-ting; Zhang, Tian-hua; Lin, Wen-qian

2015-08-10

To investigate the mechanism of paclitaxel-induced lung injury and its amelioration by parecoxib sodium. In this study, rats were randomly divided into: the control group (Con); the paclitaxel chemotherapy group (Pac); the paclitaxel+ parecoxib sodium intervention group (Pac + Pare); and the parecoxib sodium group (Pare). We observed changes in alveolar ventilation function, alveolar-capillary membrane permeability, lung tissue pathology and measured the levels of inflammatory cytokines and cyclooxygenase-2 (Cox-2) in lung tissue, the expression of tight junction proteins (Zo-1 and Claudin-4). Compared with the Con group, the lung tissue of the Pac group showed significantly increased expression of Cox-2 protein (p < 0.01), significant lung tissue inflammatory changes, significantly increased expression of inflammatory cytokines, decreased expression of Zo-1 and Claudin-4 proteins (p < 0.01), increased alveolar-capillary membrane permeability (p < 0.01), and reduced ventilation function (p < 0.01). Notably, in Pac + Pare group, intraperitoneal injection of parecoxib sodium led to decreased Cox-2 and ICAM-1 levels and reduced inflammatory responses, the recovered expression of Zo-1 and Claudin-4, reduced level of indicators reflecting the high permeability state, and close-to-normal levels of ventilation function. Intervention by the Cox-2-specific inhibitor parecoxib sodium can block this damage.

Paclitaxel-induced lung injury and its amelioration by parecoxib sodium

PubMed Central

Liu, Wen-jie; Zhong, Zhong-jian; Cao, Long-hui; Li, Hui-ting; Zhang, Tian-hua; Lin, Wen-qian

2015-01-01

To investigate the mechanism of paclitaxel-induced lung injury and its amelioration by parecoxib sodium. In this study, rats were randomly divided into: the control group (Con); the paclitaxel chemotherapy group (Pac); the paclitaxel+ parecoxib sodium intervention group (Pac + Pare); and the parecoxib sodium group (Pare). We observed changes in alveolar ventilation function, alveolar-capillary membrane permeability, lung tissue pathology and measured the levels of inflammatory cytokines and cyclooxygenase-2 (Cox-2) in lung tissue, the expression of tight junction proteins (Zo-1 and Claudin-4). Compared with the Con group, the lung tissue of the Pac group showed significantly increased expression of Cox-2 protein (p < 0.01), significant lung tissue inflammatory changes, significantly increased expression of inflammatory cytokines, decreased expression of Zo-1 and Claudin-4 proteins (p < 0.01), increased alveolar-capillary membrane permeability (p < 0.01), and reduced ventilation function (p < 0.01). Notably, in Pac + Pare group, intraperitoneal injection of parecoxib sodium led to decreased Cox-2 and ICAM-1 levels and reduced inflammatory responses, the recovered expression of Zo-1 and Claudin-4, reduced level of indicators reflecting the high permeability state, and close-to-normal levels of ventilation function. Intervention by the Cox-2-specific inhibitor parecoxib sodium can block this damage. PMID:26256764

Extracorporeal Membrane Oxygenation for Refractory Severe Respiratory Failure in Acute Interstitial Pneumonia.

PubMed

Gonçalves-Venade, Gabriela; Lacerda-Príncipe, Nuno; Roncon-Albuquerque, Roberto; Paiva, José Artur

2018-05-01

Acute interstitial pneumonia (AIP) is a rare idiopathic interstitial lung disease with rapid progressive respiratory failure and high mortality. In the present report, three cases of AIP complicated by refractory respiratory failure supported with extracorporeal membrane oxygenation (ECMO) are presented. One male and two female patients (ages 27-59) were included. Venovenous ECMO support was provided using miniaturized systems, with two-site femoro-jugular circuit configuration. Despite lung protective ventilation, prone position and neuromuscular blockade, refractory respiratory failure of unknown etiology supervened (ratio of arterial oxygen partial pressure to fractional inspired oxygen 46-130) and ECMO was initiated after 3-7 days of mechanical ventilation. AIP diagnosis was established after exclusion of infectious and noninfectious acute respiratory distress syndrome on the basis of clinical and analytical data, bronchoalveolar lavage analysis and lung imaging, with a confirmatory surgical lung biopsy revealing diffuse alveolar damage of unknown etiology. Immunosuppressive treatment consisted in high-dose corticosteroids and cyclophosphamide in one case. Two patients survived to hospital discharge. ECMO allowed AIP diagnosis and treatment in the presence of refractory respiratory failure, therefore reducing ventilator-induced lung injury and bridging lung recovery in two patients. ECMO referral should be considered in refractory respiratory failure if AIP is suspected. © 2018 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Chest CT in children: anesthesia and atelectasis.

PubMed

Newman, Beverley; Krane, Elliot J; Gawande, Rakhee; Holmes, Tyson H; Robinson, Terry E

2014-02-01

There has been an increasing tendency for anesthesiologists to be responsible for providing sedation or anesthesia during chest CT imaging in young children. Anesthesia-related atelectasis noted on chest CT imaging has proven to be a common and troublesome problem, affecting image quality and diagnostic sensitivity. To evaluate the safety and effectiveness of a standardized anesthesia, lung recruitment, controlled-ventilation technique developed at our institution to prevent atelectasis for chest CT imaging in young children. Fifty-six chest CT scans were obtained in 42 children using a research-based intubation, lung recruitment and controlled-ventilation CT scanning protocol. These studies were compared with 70 non-protocolized chest CT scans under anesthesia taken from 18 of the same children, who were tested at different times, without the specific lung recruitment and controlled-ventilation technique. Two radiology readers scored all inspiratory chest CT scans for overall CT quality and atelectasis. Detailed cardiorespiratory parameters were evaluated at baseline, and during recruitment and inspiratory imaging on 21 controlled-ventilation cases and 8 control cases. Significant differences were noted between groups for both quality and atelectasis scores with optimal scoring demonstrated in the controlled-ventilation cases where 70% were rated very good to excellent quality scans compared with only 24% of non-protocol cases. There was no or minimal atelectasis in 48% of the controlled ventilation cases compared to 51% of non-protocol cases with segmental, multisegmental or lobar atelectasis present. No significant difference in cardiorespiratory parameters was found between controlled ventilation and other chest CT cases and no procedure-related adverse events occurred. Controlled-ventilation infant CT scanning under general anesthesia, utilizing intubation and recruitment maneuvers followed by chest CT scans, appears to be a safe and effective method to obtain reliable and reproducible high-quality, motion-free chest CT images in children.

Atelectasis is inversely proportional to transpulmonary pressure during weaning from ventilator support in a large animal model.

PubMed

Gudmundsson, M; Perchiazzi, G; Pellegrini, M; Vena, A; Hedenstierna, G; Rylander, C

2018-01-01

In mechanically ventilated, lung injured, patients without spontaneous breathing effort, atelectasis with shunt and desaturation may appear suddenly when ventilator pressures are decreased. It is not known how such a formation of atelectasis is related to transpulmonary pressure (P L ) during weaning from mechanical ventilation when the spontaneous breathing effort is increased. If the relation between P L and atelectasis were known, monitoring of P L might help to avoid formation of atelectasis and cyclic collapse during weaning. The main purpose of this study was to determine the relation between P L and atelectasis in an experimental model representing weaning from mechanical ventilation. Dynamic transverse computed tomography scans were acquired in ten anaesthetized, surfactant-depleted pigs with preserved spontaneous breathing, as ventilator support was lowered by sequentially reducing inspiratory pressure and positive end expiratory pressure in steps. The volumes of gas and atelectasis in the lungs were correlated with P L obtained using oesophageal pressure recordings. Work of breathing (WOB) was assessed from Campbell diagrams. Gradual decrease in P L in both end-expiration and end-inspiration caused a proportional increase in atelectasis and decrease in the gas content (linear mixed model with an autoregressive correlation matrix; P < 0.001) as the WOB increased. However, cyclic alveolar collapse during tidal ventilation did not increase significantly. We found a proportional correlation between atelectasis and P L during the 'weaning process' in experimental mild lung injury. If confirmed in the clinical setting, a gradual tapering of ventilator support can be recommended for weaning without risk of sudden formation of atelectasis. © 2017 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Impact of Extraperitoneal Dioxyde Carbon Insufflation on Respiratory Function in Anesthetized Adults: A Preliminary Study Using Electrical Impedance Tomography and Wash-out/Wash-in Technic

PubMed Central

Bordes, Julien; Mazzeo, Cecilia; Gourtobe, Philippe; Cungi, Pierre Julien; Antonini, Francois; Bourgoin, Stephane; Kaiser, Eric

2015-01-01

Background: Extraperitoneal laparoscopy has become a common technique for many surgical procedures, especially for inguinal hernia surgery. Investigations of physiological changes occurring during extraperitoneal carbon dioxide (CO2) insufflation mostly focused on blood gas changes. To date, the impact of extraperitoneal CO2 insufflation on respiratory mechanics remains unknown, whereas changes in respiratory mechanics have been extensively studied in intraperitoneal insufflation. Objectives: The aim of this study was to investigate the effects of extraperitoneal CO2 insufflation on respiratory mechanics. Patients and Methods: A prospective and observational study was performed on nine patients undergoing laparoscopic inguinal hernia repair. Anesthetic management and intraoperative care were standardized. All patients were mechanically ventilated with a tidal volume of 8 mL/kg using an Engström Carestation ventilator (GE Healthcare). Ventilation distribution was assessed by electrical impedance tomography (EIT). End-expiratory lung volume (EELV) was measured by a nitrogen wash-out/wash-in method. Ventilation distribution, EELV, ventilator pressures and hemodynamic parameters were assessed before extraperitoneal insufflation, and during insufflation with a PEEP of 0 cmH2O, 5 cmH20 and of 10 cmH20. Results: EELV and thoracopulmonary compliance were significantly decreased after extraperitoneal insufflation. Ventilation distribution was significantly higher in ventral lung regions during general anesthesia and was not modified after insufflation. A 10 cmH20 PEEP application resulted in a significant increase in EELV, and a shift of ventilation toward the dorsal lung regions. Conclusions: Extraperitoneal insufflation decreased EELV and thoracopulmonary compliance. Application of a 10 cmH20 PEEP increased EELV and homogenized ventilation distribution. This preliminary clinical study showed that extraperitoneal insufflation worsened respiratory mechanics, which may justify further investigations to evaluate the clinical impact. PMID:25789238

[The clinical effect of airway pressure release ventilation for acute lung injury/acute respiratory distress syndrome].

PubMed

Song, Shaohua; Tian, Huiyu; Yang, Xiufen; Hu, Zhenjie

2016-01-01

To evaluate the effect of airway pressure release ventilation (APRV) in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS), to evaluate the extent of ventilator-induced lung injury (VILI), and to explore its possible mechanism. A prospective study was conducted in the Department of Critical Care Medicine of the First Hospital of Hebei Medical University from December 2010 to February 2012. The patients with ALI/ARDS were enrolled. They were randomly divided into two groups. The patients in APRV group were given APRV pattern, while those in control group were given lung protection ventilation, synchronized intermittent mandatory ventilation with positive end-expiratory pressure (SIMV+PEEP). All patients were treated with AVEA ventilator. The parameters such as airway peak pressure (Ppeak), mean airway pressure (Pmean), pulse oxygen saturation (SpO2), mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), arterial blood gas, urine output (UO), the usage of sedation and muscle relaxation drugs were recorded. AVEA ventilator "turning point (Pflex) operation" was used to describe the quasi-static pressure volume curve (P-V curve). High and low inflection point (UIP, LIP) and triangular Pflex volume (Vdelta) were automatically measured and calculated. The ventilation parameters were set, and the 24-hour P-V curve was recorded again in order to be compared with subsequent results. Venous blood was collected before treatment, 24 hours and 48 hours after ventilation to measure lung surfactant protein D (SP-D) and large molecular mucus in saliva (KL-6) by enzyme linked immunosorbent assay (ELISA), and the correlation between the above two parameters and prognosis on 28 days was analyzed by multinomial logistic regression. Twenty-six patients with ALI/ARDS were enrolled, and 22 of them completed the test with 10 in APRV group and 12 in control group. The basic parameters and P-V curves between two groups were similar before the test. After 24 hours and 48 hours, mechanical ventilation was given in both groups. The patients' oxygenation was improved significantly, though there were no significant changes in hemodynamic parameters. The Pmean (cmH2O, 1 cmH2O = 0.098 kPa) in APRV group was significantly higher than that in control group (24 hours: 24.20±4.59 vs. 17.50±3.48, P < 0.01; 48 hours: 18.10±4.30 vs. 15.00±2.59, P < 0.05). After ventilation for 24 hours, the ratio of patients with increased Vdelta in APRV group was higher than that in control group (90% vs. 75%), but without statistical difference (P > 0.05). The SP-D level (μg/L) in serum in APRV group showed a tendency of increase (increased from 19.70±7.34 to 27.61±10.21, P < 0.05), in contrast there was a tendency of decrease in control group (decreased from 21.83±7.31 to 16.58±2.90, P > 0.05), the difference between the two groups was statistically significant (P < 0.05). After 48-hour ventilation, SP-D in APRV group was decreased, but no change was found in control group, and no significant difference was found as compared with that of the control group (16.45±8.17 vs. 17.20±4.59, P > 0.05). There was no significant difference in serum KL-6 between the two groups before and after ventilation. The SP-D and KL-6 levels in serum were unrelated with 28-day survival rate of the patients. The odds ratio (OR) of SP-D were 0.900 [95% confidence interval (95%CI) = 0.719-1.125], 1.054 (95%CI = 0.878-1.266), 1.143 (95%CI = 0.957-1.365), and the OR of KL-6 were 1.356 (95%CI = 0.668-2.754), 0.658 (95%CI = 0.161-2.685), 0.915 (95%CI = 0.350-2.394) before the test, 24 hours and 48 hours after ventilation (all P > 0.05). APRV was similar to lung protective ventilation strategy in oxygenation and improvements in the lung mechanics parameters. APRV with a higher Pmean can recruit alveolar more effectively, and it had no impact on hemo-dynamics, but might exacerbate VILI.

Lung Transcriptomics during Protective Ventilatory Support in Sepsis-Induced Acute Lung Injury

PubMed Central

Acosta-Herrera, Marialbert; Lorenzo-Diaz, Fabian; Pino-Yanes, Maria; Corrales, Almudena; Valladares, Francisco; Klassert, Tilman E.; Valladares, Basilio; Slevogt, Hortense; Ma, Shwu-Fan

2015-01-01

Acute lung injury (ALI) is a severe inflammatory process of the lung. The only proven life-saving support is mechanical ventilation (MV) using low tidal volumes (LVT) plus moderate to high levels of positive end-expiratory pressure (PEEP). However, it is currently unknown how they exert the protective effects. To identify the molecular mechanisms modulated by protective MV, this study reports transcriptomic analyses based on microarray and microRNA sequencing in lung tissues from a clinically relevant animal model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP) in male Sprague-Dawley rats. At 24 hours post-CLP, septic animals were randomized to three ventilatory strategies: spontaneous breathing, LVT (6 ml/kg) plus 10 cmH2O PEEP and high tidal volume (HVT, 20 ml/kg) plus 2 cmH2O PEEP. Healthy, non-septic, non-ventilated animals served as controls. After 4 hours of ventilation, lung samples were obtained for histological examination and gene expression analysis using microarray and microRNA sequencing. Validations were assessed using parallel analyses on existing publicly available genome-wide association study findings and transcriptomic human data. The catalogue of deregulated processes differed among experimental groups. The ‘response to microorganisms’ was the most prominent biological process in septic, non-ventilated and in HVT animals. Unexpectedly, the ‘neuron projection morphogenesis’ process was one of the most significantly deregulated in LVT. Further support for the key role of the latter process was obtained by microRNA studies, as four species targeting many of its genes (Mir-27a, Mir-103, Mir-17-5p and Mir-130a) were found deregulated. Additional analyses revealed 'VEGF signaling' as a central underlying response mechanism to all the septic groups (spontaneously breathing or mechanically ventilated). Based on this data, we conclude that a co-deregulation of 'VEGF signaling' along with 'neuron projection morphogenesis', which have been never anticipated in ALI pathogenesis, promotes lung-protective effects of LVT with high levels of PEEP. PMID:26147972

Protective Lung Ventilation and Morbidity After Pulmonary Resection: A Propensity Score-Matched Analysis.

PubMed

Amar, David; Zhang, Hao; Pedoto, Alessia; Desiderio, Dawn P; Shi, Weiji; Tan, Kay See

2017-07-01

Protective lung ventilation (PLV) during one-lung ventilation (OLV) for thoracic surgery is frequently recommended to reduce pulmonary complications. However, limited outcome data exist on whether PLV use during OLV is associated with less clinically relevant pulmonary morbidity after lung resection. Intraoperative data were prospectively collected in 1080 patients undergoing pulmonary resection with OLV, intentional crystalloid restriction, and mechanical ventilation to maintain inspiratory peak airway pressure <30 cm H2O. Other ventilator settings and all aspects of anesthetic management were at the discretion of the anesthesia care team. We defined PLV and non-PLV as <8 or ≥8 mL/kg (predicted body weight) mean tidal volume. The primary outcome was the occurrence of pneumonia and/or acute respiratory distress syndrome (ARDS). Propensity score matching was used to generate PLV and non-PLV groups with comparable characteristics. Associations between outcomes and PLV status were analyzed by exact logistic regression, with matching as cluster in the anatomic and nonanatomic lung resection cohorts. In the propensity score-matched analysis, the incidence of pneumonia and/or ARDS among patients who had an anatomic lung resection was 9/172 (5.2%) in the non-PLV compared to the PLV group 7/172 (4.1%; odds ratio, 1.29; 95% confidence interval, 0.48-3.45, P= .62). The incidence of pneumonia and/or ARDS in patients who underwent nonanatomic resection was 3/118 (2.5%) in the non-PLV compared to the PLV group, 1/118 (0.9%; odds ratio, 3.00; 95% confidence interval, 0.31-28.84, P= .34). In this prospective observational study, we found no differences in the incidence of pneumonia and/or ARDS between patients undergoing lung resection with tidal volumes <8 or ≥8 mL/kg. Our data suggest that when fluid restriction and peak airway pressures are limited, the clinical impact of PLV in this patient population is small. Future randomized trials are needed to better understand the benefits of a small tidal volume strategy during OLV on clinically important outcomes.

Prevention of abnormal pulmonary mechanics in the postmortem guinea pig lung.

PubMed

Reynolds, A M; McEvoy, R D

1988-04-01

Severe postmortem bronchoconstriction has been shown previously in guinea pig lungs and linked to pulmonary blood loss during exsanguination (Lai et al., J. Appl. Physiol. 56: 308-314, 1984). To reexamine this phenomenon we measured postmortem airway function in anesthetized open-chest guinea pigs after sudden circulatory arrest. Animals were divided into 4 groups of 10 and ventilated for 15 min postmortem with different gases: 1) room air, 2) conditioned air, 3) dry 5% CO2-21% O2-74% N2, and 4) conditioned 5% CO2-21% O2-74% N2. In room air-ventilated lungs there was a 50% decrease in dynamic compliance (Cdyn) by 15 min and marked gas trapping compared with control lungs. Conditioning the room air did not attenuate these changes, but when 5% CO2 was added to the conditioned postmortem inspirate, gas trapping was eliminated and the fall in Cdyn was almost abolished. Ventilation with a dry 5% CO2 gas mixture at room temperature resulted in a 31% fall in Cdyn at 15 min but no gas trapping. We conclude that marked abnormalities of airway function occur postmortem in room air-ventilated guinea pig lungs in the absence of pulmonary blood loss. The changes are mainly due to airway hypocarbia, a known cause of bronchoconstriction, but a reduction in Cdyn can also occur if there is marked airway cooling and drying. Acute postmortem airway dysfunction can be prevented in the guinea pig by maintaining normal airway gas composition.

Performance of Portable Ventilators at Altitude

DTIC Science & Technology

2015-03-30

collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT...Deploying ventilators that can maintain a consistent tidal volume (VT) delivery at various altitudes is imperative for lung protection when...performance of mechanical ventilators calibrated for operation at sea level. Deploying ventilators that can maintain a consistent tidal volume (VT) delivery

High-frequency oscillatory ventilation in ALI/ARDS.

PubMed

Ali, Sammy; Ferguson, Niall D

2011-07-01

In the last 2 decades, our goals for mechanical ventilatory support in patients with acute respiratory distress syndrome (ARDS) or acute lung injury (ALI) have changed dramatically. Several randomized controlled trials have built on a substantial body of preclinical work to demonstrate that the way in which we employ mechanical ventilation has an impact on important patient outcomes. Avoiding ventilator-induced lung injury (VILI) is now a major focus when clinicians are considering which ventilatory strategy to employ in patients with ALI/ARDS. Physicians are searching for methods that may further limit VILI, while still achieving adequate gas exchange. Copyright © 2011 Elsevier Inc. All rights reserved.

Time course of lung inflammatory and fibrogenic responses during protective mechanical ventilation in healthy rats.

PubMed

Krebs, Joerg; Pelosi, Paolo; Tsagogiorgas, Charalambos; Haas, Jenny; Yard, Benito; Rocco, Patricia R M; Luecke, Thomas

2011-09-15

This study aimed to assess pulmonary inflammatory and fibrogenic responses and their impact on lung mechanics and histology in healthy rats submitted to protective mechanical ventilation for different experimental periods. Eighteen Wistar rats were randomized to undergo open lung-mechanical ventilation (OL-MV) for 1, 6 or 12 h. Following a recruitment maneuver, a decremental PEEP trial was performed and PEEP set according to the minimal respiratory system static elastance. Respiratory system, lung, and chest-wall elastance and gas-exchange were maintained throughout the 12 h experimental period. Histological lung injury score remained low at 1 and 6 h, but was higher at 12 h due to overinflation. A moderate inflammatory response was observed with a distinct peak at 6h. Compared to unventilated controls, type I procollagen mRNA expression was decreased at 1 and 12h, while type III procollagen expression decreased throughout the 12h experimental period. In conclusion, OL-MV in healthy rats yielded overinflation after 6 h even though respiratory elastance and gas-exchange were preserved for up to 12 h. Copyright © 2011 Elsevier B.V. All rights reserved.

Ventilation inhomogeneity in obstructive lung diseases measured by electrical impedance tomography: a simulation study.

PubMed

Schullcke, B; Krueger-Ziolek, S; Gong, B; Jörres, R A; Mueller-Lisse, U; Moeller, K

2017-10-10

Electrical impedance tomography (EIT) has mostly been used in the Intensive Care Unit (ICU) to monitor ventilation distribution but is also promising for the diagnosis in spontaneously breathing patients with obstructive lung diseases. Beside tomographic images, several numerical measures have been proposed to quantitatively assess the lung state. In this study two common measures, the 'Global Inhomogeneity Index' and the 'Coefficient of Variation' were compared regarding their capability to reflect the severity of lung obstruction. A three-dimensional simulation model was used to simulate obstructed lungs, whereby images were reconstructed on a two-dimensional domain. Simulations revealed that minor obstructions are not adequately recognized in the reconstructed images and that obstruction above and below the electrode plane may result in misleading values of inhomogeneity measures. EIT measurements on several electrode planes are necessary to apply these measures in patients with obstructive lung diseases in a promising manner.

The 'cardiac-lung mass' artifact: an echocardiographic sign of lung atelectasis and/or pleural effusion

PubMed Central

Karabinis, Andreas; Saranteas, Theodosios; Karakitsos, Dimitrios; Lichtenstein, Daniel; Poularas, John; Yang, Clifford; Stefanadis, Christodoulos

2008-01-01

Introduction We conducted an ultrasound study to investigate echocardiographic artifacts in mechanically ventilated patients with lung pathology. Methods A total of 205 mechanically ventilated patients who exhibited lung atelectasis and/or pleural effusion were included in this 36-month study. The patients underwent lung echography and transthoracic echocardiography, with a linear 5 to 10 MHz and with a 1.5 to 3.6 MHz wide-angle phased-array transducer, respectively. Patients were examined by two experienced observers who were blinded to each other's interpretation. Results A total of 124 patients (60,48%) were hospitalized because of multiple trauma; 60 patients (29,26%) because of respiratory insufficiency, and 21 (10,24%) because of recent postoperative surgery. The mean duration ( ± standard deviation) of hospitalization was 35 ± 27 days. An intracardiac artifact was documented in 17 out of 205 patients (8.29%) by echocardiography. It was visible only in the apical views, whereas subsequent transesophageal echocardiography revealed no abnormalities. The artifact consisted of a mobile component that exhibited, on M-mode, a pattern of respiratory variation similar to the lung 'sinusoid sign'. Lung echography revealed lung atelectasis and/or pleural effusion adjacent to the heart, and a similar M-mode pattern was observed. The artifact was recorded within the left cardiac chambers in 11 cases and within the right cardiac chambers in six. Conclusions Lung atelectasis and/or pleural effusion may create a mirror image, intracardiac artifact in mechanically ventilated patients. The latter was named the 'cardiac-lung mass' artifact to underline the important diagnostic role of both echocardiography and lung echography in these patients. Trial registration This trial is ISRCTN registered: ISRCTN 49216096. PMID:18826590

No change in the regional distribution of tidal volume during lateral posture in mechanically ventilated patients assessed by electrical impedance tomography.

PubMed

Bein, Thomas; Ploner, Franz; Ritzka, Markus; Pfeifer, Michael; Schlitt, Hans J; Graf, Bernhard M

2010-07-01

We assessed the distribution of regional lung ventilation during moderate and steep lateral posture using electrical impedance tomography (EIT) in mechanically ventilated patients. Seven patients were placed on a kinetic treatment table. An elastic belt containing 16 electrodes was placed around the chest and was connected to the EIT device. Patients were moved to left and right lateral positions in a stepwise (10 degrees ) mode up to 60 degrees. EIT images [arbitrary units (AU)] were generated and scanned for assessment of relative ventilation distribution changes [tidal volume (V(T))]. A calibration procedure of arbitrary units (AUs) versus ventilator-derived V(T) performed in all patients during three predefined positions (supine, 60 degrees-left dependent and 60 degrees-right-dependent) showed a significant correlation between V(T) in supine, left and right lateral positions with the corresponding AUs (r(2) = 0.356, P<0.05). Changes in V(T) were calculated and compared to supine position, and specific regions of interest (ROIs) were analysed. In our study, in contrast to recent findings, a change in lateral positions did not induce a significant change in regional tidal volume distribution. In right lateral positions, a broader variation of V(T) with a trend towards an increase in the dependently positioned lung was observed in comparison with supine. Lateral positioning promotes the redistribution of ventilation to the ventral regions of the lung. The use of EIT technology might become a helpful tool for understanding and guiding posture therapy in mechanically ventilated patients.

No change in the regional distribution of tidal volume during lateral posture in mechanically ventilated patients assessed by electrical impedance tomography

PubMed Central

Bein, Thomas; Ploner, Franz; Ritzka, Markus; Pfeifer, Michael; Schlitt, Hans J; Graf, Bernhard M

2010-01-01

We assessed the distribution of regional lung ventilation during moderate and steep lateral posture using electrical impedance tomography (EIT) in mechanically ventilated patients. Seven patients were placed on a kinetic treatment table. An elastic belt containing 16 electrodes was placed around the chest and was connected to the EIT device. Patients were moved to left and right lateral positions in a stepwise (10°) mode up to 60°. EIT images [arbitrary units (AU)] were generated and scanned for assessment of relative ventilation distribution changes [tidal volume (VT)]. A calibration procedure of arbitrary units (AUs) versus ventilator-derived VT performed in all patients during three predefined positions (supine, 60°-left dependent and 60°-right-dependent) showed a significant correlation between VT in supine, left and right lateral positions with the corresponding AUs (r2 = 0·356, P<0·05). Changes in VT were calculated and compared to supine position, and specific regions of interest (ROIs) were analysed. In our study, in contrast to recent findings, a change in lateral positions did not induce a significant change in regional tidal volume distribution. In right lateral positions, a broader variation of VT with a trend towards an increase in the dependently positioned lung was observed in comparison with supine. Lateral positioning promotes the redistribution of ventilation to the ventral regions of the lung. The use of EIT technology might become a helpful tool for understanding and guiding posture therapy in mechanically ventilated patients. PMID:20491842

Infrared end-tidal CO2 measurement does not accurately predict arterial CO2 values or end-tidal to arterial PCO2 gradients in rabbits with lung injury.

PubMed

Hopper, A O; Nystrom, G A; Deming, D D; Brown, W R; Peabody, J L

1994-03-01

End-tidal PCO2 (PETCO2) measurements from two commercially available neonatal infrared capnometers with different sampling systems and a mass spectrometer were compared with arterial PCO2 (PaCO2) to determine whether the former could predict the latter in mechanically ventilated rabbits with and without lung injury. The effects of tidal volume, ventilator frequency and type of lung injury on the gradient between PETCO2 and PaCO2 (delta P(a-ET)CO2) were evaluated. Twenty rabbits were studied: 10 without lung injury, 5 with saline lavage and 5 with lung injury by meconium instillation. Paired measurements of PETCO2 by two infrared capnometers and a mass spectrometer were compared to PaCO2. In the rabbits without lung injury, the values from the infrared capnometers and mass spectrometer correlated strongly with PaCO2 (r > or = 0.91) despite differences in the slopes of the linear regression between PETCO2 and PaCO2 and in delta P(a-ET)CO2 (P < 0.05). Values from the mainstream IR-capnometer more closely approximated the line of identity than the regression between the sidestream IR-capnometer values or the mass spectrometer and PaCO2, but tended to overestimate PaCO2. The delta P(a-ET)CO2 was similar at all tidal volumes and ventilator frequencies, regardless of capnometer type. In the rabbits with induced lung injury, while there was a positive correlation between the slopes of the regression between PETCO2 and PaCO2 for both capnometers (r > or = 0.70), none of the regression slopes approximated the line of identity. The delta P(a-ET)CO2 was greater in rabbits with injured than noninjured lungs (P < 0.05). The delta P(a-ET)CO2 was similar among capnometers regardless of tidal volume, ventilator frequency, or type of lung injury. The 95% confidence interval of plots PaCO2 against PETCO2 was large for rabbits with injured and noninjured lungs.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of peep on lung injury, pulmonary function, systemic circulation and mortality in animals with uninjured lungs—a systematic review

PubMed Central

Pisani, Luigi; Chaves, Renato Carneiro de Freitas; Amorim, Thiago Chaves; Cherpanath, Thomas; Determann, Rogier; Dongelmans, Dave A.; Paulus, Frederique; Tuinman, Pieter Roel; Pelosi, Paolo; Gama de Abreu, Marcelo; Schultz, Marcus J.; Serpa Neto, Ary

2018-01-01

It is well-known that positive end-expiratory pressure (PEEP) can prevent ventilator-induced lung injury (VILI) and improve pulmonary physiology in animals with injured lungs. It’s uncertain whether PEEP has similar effects in animals with uninjured lungs. A systematic review of randomized controlled trials (RCTs) comparing different PEEP levels in animals with uninjured lungs was performed. Trials in animals with injured lungs were excluded, as were trials that compared ventilation strategies that also differed with respect to other ventilation settings, e.g., tidal volume size. The search identified ten eligible trials in 284 animals, including rodents and small as well as large mammals. Duration of ventilation was highly variable, from 1 to 6 hours and tidal volume size varied from 7 to 60 mL/kg. PEEP ranged from 3 to 20 cmH2O, and from 0 to 5 cmH2O, in the ‘high PEEP’ or ‘PEEP’ arms, and in the ‘low PEEP’ or ‘no PEEP’ arms, respectively. Definitions used for lung injury were quite diverse, as were other outcome measures. The effects of PEEP, at any level, on lung injury was not straightforward, with some trials showing less injury with ‘high PEEP’ or ‘PEEP’ and other trials showing no benefit. In most trials, ‘high PEEP’ or ‘PEEP’ was associated with improved respiratory system compliance, and better oxygen parameters. However, ‘high PEEP’ or ‘PEEP’ was also associated with occurrence of hypotension, a reduction in cardiac output, or development of hyperlactatemia. There were no differences in mortality. The number of trials comparing ‘high PEEP’ or ‘PEEP’ with ‘low PEEP’ or ‘no PEEP’ in animals with uninjured lungs is limited, and results are difficult to compare. Based on findings of this systematic review it’s uncertain whether PEEP, at any level, truly prevents lung injury, while most trials suggest potential harmful effects on the systemic circulation. PMID:29430442

Ion beam induced 18F-radiofluorination: straightforward synthesis of gaseous radiotracers for the assessment of regional lung ventilation using positron emission tomography.

PubMed

Gómez-Vallejo, V; Lekuona, A; Baz, Z; Szczupak, B; Cossío, U; Llop, J

2016-09-29

A simple, straightforward and efficient method for the synthesis of [ 18 F]CF 4 and [ 18 F]SF 6 based on an ion beam-induced isotopic exchange reaction is presented. Positron emission tomography ventilation studies in rodents using [ 18 F]CF 4 showed a uniform distribution of the radiofluorinated gas within the lungs and rapid elimination after discontinuation of the administration.

Electrical impedance tomography

PubMed Central

Lobo, Beatriz; Hermosa, Cecilia; Abella, Ana

2018-01-01

Continuous assessment of respiratory status is one of the cornerstones of modern intensive care unit (ICU) monitoring systems. Electrical impedance tomography (EIT), although with some constraints, may play the lead as a new diagnostic and guiding tool for an adequate optimization of mechanical ventilation in critically ill patients. EIT may assist in defining mechanical ventilation settings, assess distribution of tidal volume and of end-expiratory lung volume (EELV) and contribute to titrate positive end-expiratory pressure (PEEP)/tidal volume combinations. It may also quantify gains (recruitment) and losses (overdistention or derecruitment), granting a more realistic evaluation of different ventilator modes or recruitment maneuvers, and helping in the identification of responders and non-responders to such maneuvers. Moreover, EIT also contributes to the management of life-threatening lung diseases such as pneumothorax, and aids in guiding fluid management in the critical care setting. Lastly, assessment of cardiac function and lung perfusion through electrical impedance is on the way. PMID:29430443

Abolished ventilation and perfusion of lung caused by blood clot in the left main bronchus: auto-downregulation of pulmonary arterial blood supply.

PubMed

Afzelius, P; Bergmann, A; Henriksen, J H

2015-09-15

It is generally assumed that the lungs possess arterial autoregulation associated with bronchial obstruction. A patient with pneumonia and congestive heart failure unexpectedly developed frequent haemoptysis. High-resolution CT and diagnostic CT were performed as well as ventilation/perfusion (V/Q) scintigraphy with single-photon emission CT (SPECT)/CT. V/Q SPECT/CT demonstrated abolished ventilation due to obstruction of the left main bronchus and markedly reduced perfusion of the entire left lung, a condition that was completely reversed after removal of a blood clot. We present the first pictorially documented case of hypoxia-induced pulmonary vasoconstriction and flow shift in a main pulmonary artery due to a complete intrinsic obstruction of the ipsilateral main bronchus. The condition is reversible, contingent on being relieved within a few days. 2015 BMJ Publishing Group Ltd.

Insights into Ventilatory Inhomogeneity from Respiratory Measurements on Spacelab Mission D-2

NASA Technical Reports Server (NTRS)

Paiva, Manuel; Verbanck, Sylvia; Linnarsson, Dag; Prisk, Kim; West, John B.

1996-01-01

The relative contributions of inter-regional and intra-regional ventilation inhomogeneities of Spacelab astronauts are studied. The classical theory of ventilation distribution in the lung is that the top-to-bottom (inter-regional) ventilation inhomogeneities are primarily gravity dependent, whereas the peripheral (intra-regional) ventilation distribution is gravity independent. Argon rebreathing tests showed that gravity independent specific ventilation (ventilation per unit volume) inhomogeneities are at least as large as gravity dependent ones. Single breath tests with helium and sulfur hexafluoride showed the different sensitivity of these gases to microgravity.

Model-based setting of inspiratory pressure and respiratory rate in pressure-controlled ventilation.

PubMed

Schranz, C; Becher, T; Schädler, D; Weiler, N; Möller, K

2014-03-01

Mechanical ventilation carries the risk of ventilator-induced-lung-injury (VILI). To minimize the risk of VILI, ventilator settings should be adapted to the individual patient properties. Mathematical models of respiratory mechanics are able to capture the individual physiological condition and can be used to derive personalized ventilator settings. This paper presents model-based calculations of inspiration pressure (pI), inspiration and expiration time (tI, tE) in pressure-controlled ventilation (PCV) and a retrospective evaluation of its results in a group of mechanically ventilated patients. Incorporating the identified first order model of respiratory mechanics in the basic equation of alveolar ventilation yielded a nonlinear relation between ventilation parameters during PCV. Given this patient-specific relation, optimized settings in terms of minimal pI and adequate tE can be obtained. We then retrospectively analyzed data from 16 ICU patients with mixed pathologies, whose ventilation had been previously optimized by ICU physicians with the goal of minimization of inspiration pressure, and compared the algorithm's 'optimized' settings to the settings that had been chosen by the physicians. The presented algorithm visualizes the patient-specific relations between inspiration pressure and inspiration time. The algorithm's calculated results highly correlate to the physician's ventilation settings with r = 0.975 for the inspiration pressure, and r = 0.902 for the inspiration time. The nonlinear patient-specific relations of ventilation parameters become transparent and support the determination of individualized ventilator settings according to therapeutic goals. Thus, the algorithm is feasible for a variety of ventilated ICU patients and has the potential of improving lung-protective ventilation by minimizing inspiratory pressures and by helping to avoid the build-up of clinically significant intrinsic positive end-expiratory pressure.

Mild hypothermia increases pulmonary anti-inflammatory response during protective mechanical ventilation in a piglet model of acute lung injury.

PubMed

Cruces, Pablo; Erranz, Benjamín; Donoso, Alejandro; Carvajal, Cristóbal; Salomón, Tatiana; Torres, María Fernanda; Díaz, Franco

2013-11-01

The effects of mild hypothermia (HT) on acute lung injury (ALI) are unknown in species with metabolic rate similar to that of humans, receiving protective mechanical ventilation (MV). We hypothesized that mild hypothermia would attenuate pulmonary and systemic inflammatory responses in piglets with ALI managed with a protective MV. Acute lung injury (ALI) was induced with surfactant deactivation in 38 piglets. The animals were then ventilated with low tidal volume, moderate positive end-expiratory pressure (PEEP), and permissive hypercapnia throughout the experiment. Subjects were randomized to HT (33.5°C) or normothermia (37°C) groups over 4 h. Plasma and tissue cytokines, tissue apoptosis, lung mechanics, pulmonary vascular permeability, hemodynamic, and coagulation were evaluated. Lung interleukin-10 concentrations were higher in subjects that underwent HT after ALI induction than in those that maintained normothermia. No difference was found in other systemic and tissue cytokines. HT did not induce lung or kidney tissue apoptosis or influence lung mechanics or markers of pulmonary vascular permeability. Heart rate, cardiac output, oxygen uptake, and delivery were significantly lower in subjects that underwent HT, but no difference in arterial lactate, central venous oxygen saturation, and coagulation test was observed. Mild hypothermia induced a local anti-inflammatory response in the lungs, without affecting lung function or coagulation, in this piglet model of ALI. The HT group had lower cardiac output without signs of global dysoxia, suggesting an adaptation to the decrease in oxygen uptake and delivery. Studies are needed to determine the therapeutic role of HT in ALI. © 2013 John Wiley & Sons Ltd.

Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing

PubMed Central

Jahani, Nariman; Choi, Jiwoong; Iyer, Krishna; Hoffman, Eric A.

2015-01-01

This study aims to assess regional ventilation, nonlinearity, and hysteresis of human lungs during dynamic breathing via image registration of four-dimensional computed tomography (4D-CT) scans. Six healthy adult humans were studied by spiral multidetector-row CT during controlled tidal breathing as well as during total lung capacity and functional residual capacity breath holds. Static images were utilized to contrast static vs. dynamic (deep vs. tidal) breathing. A rolling-seal piston system was employed to maintain consistent tidal breathing during 4D-CT spiral image acquisition, providing required between-breath consistency for physiologically meaningful reconstructed respiratory motion. Registration-derived variables including local air volume and anisotropic deformation index (ADI, an indicator of preferential deformation in response to local force) were employed to assess regional ventilation and lung deformation. Lobar distributions of air volume change during tidal breathing were correlated with those of deep breathing (R2 ≈ 0.84). Small discrepancies between tidal and deep breathing were shown to be likely due to different distributions of air volume change in the left and the right lungs. We also demonstrated an asymmetric characteristic of flow rate between inhalation and exhalation. With ADI, we were able to quantify nonlinearity and hysteresis of lung deformation that can only be captured in dynamic images. Nonlinearity quantified by ADI is greater during inhalation, and it is stronger in the lower lobes (P < 0.05). Lung hysteresis estimated by the difference of ADI between inhalation and exhalation is more significant in the right lungs than that in the left lungs. PMID:26316512

Assessment of pulmonary structure-function relationships in young children and adolescents with cystic fibrosis by multivolume proton-MRI and CT.

PubMed

Pennati, Francesca; Roach, David J; Clancy, John P; Brody, Alan S; Fleck, Robert J; Aliverti, Andrea; Woods, Jason C

2018-02-19

Lung disease is the most frequent cause of morbidity and mortality in patients with cystic fibrosis (CF), and there is a shortage of sensitive biomarkers able to regionally monitor disease progression and to assess early responses to therapy. To determine the feasibility of noncontrast-enhanced multivolume MRI, which assesses intensity changes between expiratory and inspiratory breath-hold images, to detect and quantify regional ventilation abnormalities in CF lung disease, with a focus on the structure-function relationship. Retrospective. Twenty-nine subjects, including healthy young children (n = 9, 7-37 months), healthy adolescents (n = 4, 14-22 years), young children with CF lung disease (n = 10, 7-47 months), and adolescents with CF lung disease (n = 6, 8-18 years) were studied. 3D spoiled gradient-recalled sequence at 1.5T. Subjects were scanned during breath-hold at functional residual capacity (FRC) and total lung capacity (TLC) through noncontrast-enhanced MRI and CT. Expiratory-inspiratory differences in MR signal-intensity (Δ 1 H-MRI) and CT-density (ΔHU) were computed to estimate regional ventilation. MR and CT images were also evaluated using a CF-specific scoring system. Quadratic regression, Spearman's correlation, one-way analysis of variance (ANOVA). Δ 1 H-MRI maps were sensitive to ventilation heterogeneity related to gravity dependence in healthy lung and to ventilation impairment in CF lung disease. A high correlation was found between MRI and CT ventilation maps (R 2  = 0.79, P < 0.001). Globally, Δ 1 H-MRI and ΔHU decrease with increasing morphological score (respectively, R 2  = 0.56, P < 0.001 and R 2  = 0.31, P < 0.001). Locally, Δ 1 H-MRI was higher in healthy regions (median 15%) compared to regions with bronchiectasis, air trapping, consolidation, and to segments fed by airways with bronchial wall thickening (P < 0.001). Multivolume noncontrast-enhanced MRI, as a nonionizing imaging modality that can be used on nearly any MRI scanner without specialized equipment or gaseous tracers, may be particularly valuable in CF care, providing a new imaging biomarker to detect early alterations in regional lung structure-function. 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018. © 2018 International Society for Magnetic Resonance in Medicine.

Adult venovenous extracorporeal membrane oxygenation for severe respiratory failure: Current status and future perspectives.

PubMed

Sen, Ayan; Callisen, Hannelisa E; Alwardt, Cory M; Larson, Joel S; Lowell, Amelia A; Libricz, Stacy L; Tarwade, Pritee; Patel, Bhavesh M; Ramakrishna, Harish

2016-01-01

Extracorporeal membrane oxygenation (ECMO) for severe acute respiratory failure was proposed more than 40 years ago. Despite the publication of the ARDSNet study and adoption of lung protective ventilation, the mortality for acute respiratory failure due to acute respiratory distress syndrome has continued to remain high. This technology has evolved over the past couple of decades and has been noted to be safe and successful, especially during the worldwide H1N1 influenza pandemic with good survival rates. The primary indications for ECMO in acute respiratory failure include severe refractory hypoxemic and hypercarbic respiratory failure in spite of maximum lung protective ventilatory support. Various triage criteria have been described and published. Contraindications exist when application of ECMO may be futile or technically impossible. Knowledge and appreciation of the circuit, cannulae, and the physiology of gas exchange with ECMO are necessary to ensure lung rest, efficiency of oxygenation, and ventilation as well as troubleshooting problems. Anticoagulation is a major concern with ECMO, and the evidence is evolving with respect to diagnostic testing and use of anticoagulants. Clinical management of the patient includes comprehensive critical care addressing sedation and neurologic issues, ensuring lung recruitment, diuresis, early enteral nutrition, treatment and surveillance of infections, and multisystem organ support. Newer technology that delinks oxygenation and ventilation by extracorporeal carbon dioxide removal may lead to ultra-lung protective ventilation, avoidance of endotracheal intubation in some situations, and ambulatory therapies as a bridge to lung transplantation. Risks, complications, and long-term outcomes and resources need to be considered and weighed in before widespread application. Ethical challenges are a reality and a multidisciplinary approach that should be adopted for every case in consideration.

Nasal continuous positive airway pressure (CPAP) for the respiratory care of the newborn infant.

PubMed

Diblasi, Robert M

2009-09-01

Nasal continuous positive airway pressure (CPAP) is a noninvasive form of respiratory assistance that has been used to support spontaneously breathing infants with lung disease for nearly 40 years. Following reports that mechanical ventilation contributes to pulmonary growth arrest and the development of chronic lung disease, there is a renewed interest in using CPAP as the prevailing method for supporting newborn infants. Animal and human research has shown that CPAP is less injurious to the lungs than is mechanical ventilation. The major concepts that embrace lung protection during CPAP are the application of spontaneous breathing at a constant distending pressure and avoidance of intubation and positive-pressure inflations. A major topic for current research focuses on whether premature infants should be supported initially with CPAP following delivery, or after the infant has been extubated following prophylactic surfactant administration. Clinical trials have shown that CPAP reduces the need for intubation/mechanical ventilation and surfactant administration, but it is still unclear whether CPAP reduces chronic lung disease and mortality, compared to modern lung-protective ventilation techniques. Despite the successes, little is known about how best to manage patients using CPAP. It is also unclear whether different strategies or devices used to maintain CPAP play a role in improving outcomes in infants. Nasal CPAP technology has evolved over the last 10 years, and bench and clinical research has evaluated differences in physiologic effects related to these new devices. Ultimately, clinicians' abilities to perceive changes in the pathophysiologic conditions of infants receiving CPAP and the quality of airway care provided are likely to be the most influential factors in determining patient outcomes.

Hemodynamic differences between continual positive and two types of negative pressure ventilation.

PubMed

Lockhat, D; Langleben, D; Zidulka, A

1992-09-01

In seven anesthetized dogs, ventilated with matching lung volumes, tidal volumes, and respiratory rates, we compared the effects on cardiac output (CO), arterial venous oxygen saturation difference (SaO2 - SVO2), and femoral and inferior vena cava pressure (1) intermittent positive pressure ventilation with positive end-expiratory pressure (CPPV); (2) iron-lung ventilation with negative end-expiratory pressure (ILV-NEEP); (3) grid and wrap ventilation with NEEP applied to the thorax and upper abdomen (G&W-NEEP). The values of CO and SaO2 - SVO2 with ILV-NEEP were similar to those with CPPV. However, with G&W-NEEP as compared with ILV-NEEP, mean CO was greater (2.9 versus 2.6 L/min, p = 0.02) and mean (SaO2 - SVO2) was lower (26.6% versus 28.3%, p = NS). Mean PFEM-IVC was higher with G&W-NEEP than with the other types of ventilation. We conclude that (1) ILV-NEEP is hemodynamically equivalent to CPPV and (2) G&W-NEEP has less adverse hemodynamic consequences. has less adverse hemodynamic consequences.

Clinical Practice Guideline of Acute Respiratory Distress Syndrome

PubMed Central

Cho, Young-Jae; Moon, Jae Young; Shin, Ein-Soon; Kim, Je Hyeong; Jung, Hoon; Park, So Young; Kim, Ho Cheol; Sim, Yun Su; Rhee, Chin Kook; Lim, Jaemin; Lee, Seok Jeong; Lee, Won-Yeon; Lee, Hyun Jeong; Kwak, Sang Hyun; Kang, Eun Kyeong; Chung, Kyung Soo

2016-01-01

There is no well-stated practical guideline for mechanically ventilated patients with or without acute respiratory distress syndrome (ARDS). We generate strong (1) and weak (2) grade of recommendations based on high (A), moderate (B) and low (C) grade in the quality of evidence. In patients with ARDS, we recommend low tidal volume ventilation (1A) and prone position if it is not contraindicated (1B) to reduce their mortality. However, we did not support high-frequency oscillatory ventilation (1B) and inhaled nitric oxide (1A) as a standard treatment. We also suggest high positive end-expiratory pressure (2B), extracorporeal membrane oxygenation as a rescue therapy (2C), and neuromuscular blockage for 48 hours after starting mechanical ventilation (2B). The application of recruitment maneuver may reduce mortality (2B), however, the use of systemic steroids cannot reduce mortality (2B). In mechanically ventilated patients, we recommend light sedation (1B) and low tidal volume even without ARDS (1B) and suggest lung protective ventilation strategy during the operation to lower the incidence of lung complications including ARDS (2B). Early tracheostomy in mechanically ventilated patients can be performed only in limited patients (2A). In conclusion, of 12 recommendations, nine were in the management of ARDS, and three for mechanically ventilated patients. PMID:27790273

Airway pressure release ventilation: what do we know?

PubMed

Daoud, Ehab G; Farag, Hany L; Chatburn, Robert L

2012-02-01

Airway pressure release ventilation (APRV) is inverse ratio, pressure controlled, intermittent mandatory ventilation with unrestricted spontaneous breathing. It is based on the principle of open lung approach. It has many purported advantages over conventional ventilation, including alveolar recruitment, improved oxygenation, preservation of spontaneous breathing, improved hemodynamics, and potential lung-protective effects. It has many claimed disadvantages related to risks of volutrauma, increased work of breathing, and increased energy expenditure related to spontaneous breathing. APRV is used mainly as a rescue therapy for the difficult to oxygenate patients with acute respiratory distress syndrome (ARDS). There is confusion regarding this mode of ventilation, due to the different terminology used in the literature. APRV settings include the "P high," "T high," "P low," and "T low". Physicians and respiratory therapists should be aware of the different ways and the rationales for setting these variables on the ventilators. Also, they should be familiar with the differences between APRV, biphasic positive airway pressure (BIPAP), and other conventional and nonconventional modes of ventilation. There is no solid proof that APRV improves mortality; however, there are ongoing studies that may reveal further information about this mode of ventilation. This paper reviews the different methods proposed for APRV settings, and summarizes the different studies comparing APRV and BIPAP, and the potential benefits and pitfalls for APRV.

4-D segmentation and normalization of 3He MR images for intrasubject assessment of ventilated lung volumes

NASA Astrophysics Data System (ADS)

Contrella, Benjamin; Tustison, Nicholas J.; Altes, Talissa A.; Avants, Brian B.; Mugler, John P., III; de Lange, Eduard E.

2012-03-01

Although 3He MRI permits compelling visualization of the pulmonary air spaces, quantitation of absolute ventilation is difficult due to confounds such as field inhomogeneity and relative intensity differences between image acquisition; the latter complicating longitudinal investigations of ventilation variation with respiratory alterations. To address these potential difficulties, we present a 4-D segmentation and normalization approach for intra-subject quantitative analysis of lung hyperpolarized 3He MRI. After normalization, which combines bias correction and relative intensity scaling between longitudinal data, partitioning of the lung volume time series is performed by iterating between modeling of the combined intensity histogram as a Gaussian mixture model and modulating the spatial heterogeneity tissue class assignments through Markov random field modeling. Evaluation of the algorithm was retrospectively applied to a cohort of 10 asthmatics between 19-25 years old in which spirometry and 3He MR ventilation images were acquired both before and after respiratory exacerbation by a bronchoconstricting agent (methacholine). Acquisition was repeated under the same conditions from 7 to 467 days (mean +/- standard deviation: 185 +/- 37.2) later. Several techniques were evaluated for matching intensities between the pre and post-methacholine images with the 95th percentile value histogram matching demonstrating superior correlations with spirometry measures. Subsequent analysis evaluated segmentation parameters for assessing ventilation change in this cohort. Current findings also support previous research that areas of poor ventilation in response to bronchoconstriction are relatively consistent over time.

Assessment of regional ventilation distribution: comparison of vibration response imaging (VRI) with electrical impedance tomography (EIT).

PubMed

Shi, Chang; Boehme, Stefan; Bentley, Alexander H; Hartmann, Erik K; Klein, Klaus U; Bodenstein, Marc; Baumgardner, James E; David, Matthias; Ullrich, Roman; Markstaller, Klaus

2014-01-01

Vibration response imaging (VRI) is a bedside technology to monitor ventilation by detecting lung sound vibrations. It is currently unknown whether VRI is able to accurately monitor the local distribution of ventilation within the lungs. We therefore compared VRI to electrical impedance tomography (EIT), an established technique used for the assessment of regional ventilation. Simultaneous EIT and VRI measurements were performed in the healthy and injured lungs (ALI; induced by saline lavage) at different PEEP levels (0, 5, 10, 15 mbar) in nine piglets. Vibration energy amplitude (VEA) by VRI, and amplitudes of relative impedance changes (rel.ΔZ) by EIT, were evaluated in seven regions of interest (ROIs). To assess the distribution of tidal volume (VT) by VRI and EIT, absolute values were normalized to the VT obtained by simultaneous spirometry measurements. Redistribution of ventilation by ALI and PEEP was detected by VRI and EIT. The linear correlation between pooled VT by VEA and rel.ΔZ was R(2) = 0.96. Bland-Altman analysis showed a bias of -1.07±24.71 ml and limits of agreement of -49.05 to +47.36 ml. Within the different ROIs, correlations of VT-distribution by EIT and VRI ranged between R(2) values of 0.29 and 0.96. ALI and PEEP did not alter the agreement of VT between VRI and EIT. Measurements of regional ventilation distribution by VRI are comparable to those obtained by EIT.

Mechanical Ventilation as a Therapeutic Tool to Reduce ARDS Incidence.

PubMed

Nieman, Gary F; Gatto, Louis A; Bates, Jason H T; Habashi, Nader M

2015-12-01

Trauma, hemorrhagic shock, or sepsis can incite systemic inflammatory response syndrome, which can result in early acute lung injury (EALI). As EALI advances, improperly set mechanical ventilation (MV) can amplify early injury into a secondary ventilator-induced lung injury that invariably develops into overt ARDS. Once established, ARDS is refractory to most therapeutic strategies, which have not been able to lower ARDS mortality below the current unacceptably high 40%. Low tidal volume ventilation is one of the few treatments shown to have a moderate positive impact on ARDS survival, presumably by reducing ventilator-induced lung injury. Thus, there is a compelling case to be made that the focus of ARDS management should switch from treatment once this syndrome has become established to the application of preventative measures while patients are still in the EALI stage. Indeed, studies have shown that ARDS incidence is markedly reduced when conventional MV is applied preemptively using a combination of low tidal volume and positive end-expiratory pressure in both patients in the ICU and in surgical patients at high risk for developing ARDS. Furthermore, there is evidence from animal models and high-risk trauma patients that superior prevention of ARDS can be achieved using preemptive airway pressure release ventilation with a very brief duration of pressure release. Preventing rather than treating ARDS may be the way forward in dealing with this recalcitrant condition and would represent a paradigm shift in the way that MV is currently practiced.

Open lung approach versus standard protective strategies: Effects on driving pressure and ventilatory efficiency during anesthesia - A pilot, randomized controlled trial.

PubMed

Ferrando, Carlos; Suarez-Sipmann, Fernando; Tusman, Gerardo; León, Irene; Romero, Esther; Gracia, Estefania; Mugarra, Ana; Arocas, Blanca; Pozo, Natividad; Soro, Marina; Belda, Francisco J

2017-01-01

Low tidal volume (VT) during anesthesia minimizes lung injury but may be associated to a decrease in functional lung volume impairing lung mechanics and efficiency. Lung recruitment (RM) can restore lung volume but this may critically depend on the post-RM selected PEEP. This study was a randomized, two parallel arm, open study whose primary outcome was to compare the effects on driving pressure of adding a RM to low-VT ventilation, with or without an individualized post-RM PEEP in patients without known previous lung disease during anesthesia. Consecutive patients scheduled for major abdominal surgery were submitted to low-VT ventilation (6 ml·kg-1) and standard PEEP of 5 cmH2O (pre-RM, n = 36). After 30 min estabilization all patients received a RM and were randomly allocated to either continue with the same PEEP (RM-5 group, n = 18) or to an individualized open-lung PEEP (OL-PEEP) (Open Lung Approach, OLA group, n = 18) defined as the level resulting in maximal Cdyn during a decremental PEEP trial. We compared the effects on driving pressure and lung efficiency measured by volumetric capnography. OL-PEEP was found at 8±2 cmH2O. 36 patients were included in the final analysis. When compared with pre-RM, OLA resulted in a 22% increase in compliance and a 28% decrease in driving pressure when compared to pre-RM. These parameters did not improve in the RM-5. The trend of the DP was significantly different between the OLA and RM-5 groups (p = 0.002). VDalv/VTalv was significantly lower in the OLA group after the RM (p = 0.035). Lung recruitment applied during low-VT ventilation improves driving pressure and lung efficiency only when applied as an open-lung strategy with an individualized PEEP in patients without lung diseases undergoing major abdominal surgery. ClinicalTrials.gov NCT02798133.

The role of hyperpolarized 129xenon in MR imaging of pulmonary function

PubMed Central

Ebner, Lukas; Kammerman, Jeff; Driehuys, Bastiaan; Schiebler, Mark L.; Cadman, Robert V.; Fain, Sean B.

2016-01-01

In the last two decades, functional imaging of the lungs using hyperpolarized noble gases has entered the clinical stage. Both helium (3 He) and xenon (129Xe) gas have been thoroughly investigated for their ability to assess both the global and regional patterns of lung ventilation. With advances in polarizer technology and the current transition towards the widely available 129Xe gas, this method is ready for translation to the clinic. Currently, hyperpolarized (HP) noble gas lung MRI is limited to selected academic institutions; yet, the promising results from initial clinical trials have drawn the attention of the pulmonary medicine community. HP 129Xe MRI provides not only 3-dimensional ventilation imaging, but also unique capabilities for probing regional lung physiology. In this review article, we aim to (1) provide a brief overview of current ventilation MR imaging techniques, (2) emphasize the role of HP 129Xe MRI within the array of different imaging strategies, (3) discuss the unique imaging possibilities with HP 129Xe MRI, and (4) propose clinical applications. PMID:27707585

Effect of protective ventilation on postoperative pulmonary complications in patients undergoing general anaesthesia: a meta-analysis of randomised controlled trials.

PubMed

Tao, Tianzhu; Bo, Lulong; Chen, Feng; Xie, Qun; Zou, Yun; Hu, Baoji; Li, Jinbao; Deng, Xiaoming

2014-06-24

To determine whether anaesthetised patients undergoing surgery could benefit from intraoperative protective ventilation strategies. MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched up to February 2014. Eligible studies evaluated protective ventilation versus conventional ventilation in anaesthetised patients without lung injury at the onset of mechanical ventilation. The primary outcome was the incidence of postoperative pulmonary complications. Included studies must report at least one of the following end points: the incidence of atelectasis or acute lung injury or pulmonary infections. Four studies (594 patients) were included. Meta-analysis using a random effects model showed a significant decrease in the incidence of atelectasis (OR=0.36; 95% CI 0.22 to 0.60; p<0.0001; I(2)=0%) and pulmonary infections (OR=0.30; 95% CI 0.14 to 0.68; p=0.004; I(2)=20%) in patients receiving protective ventilation. Ventilation with protective strategies did not reduce the incidence of acute lung injury (OR=0.40; 95% CI 0.07 to 2.15; p=0.28; I(2)=12%), all-cause mortality (OR=0.77; 95% CI 0.33 to 1.79; p=0.54; I(2)=0%), length of hospital stay (weighted mean difference (WMD)=-0.52 day, 95% CI -4.53 to 3.48 day; p=0.80; I(2)=63%) or length of intensive care unit stay (WMD=-0.55 day, 95% CI -2.19 to 1.09 day; p=0.51; I(2)=39%). Intraoperative use of protective ventilation strategies has the potential to reduce the incidence of postoperative pulmonary complications in patients undergoing general anaesthesia. Prospective, well-designed clinical trials are warranted to confirm the beneficial effects of protective ventilation strategies in surgical patients. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Effect of protective ventilation on postoperative pulmonary complications in patients undergoing general anaesthesia: a meta-analysis of randomised controlled trials

PubMed Central

Tao, Tianzhu; Bo, Lulong; Chen, Feng; Xie, Qun; Zou, Yun; Hu, Baoji; Li, Jinbao; Deng, Xiaoming

2014-01-01

Objective To determine whether anaesthetised patients undergoing surgery could benefit from intraoperative protective ventilation strategies. Methods MEDLINE, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) were searched up to February 2014. Eligible studies evaluated protective ventilation versus conventional ventilation in anaesthetised patients without lung injury at the onset of mechanical ventilation. The primary outcome was the incidence of postoperative pulmonary complications. Included studies must report at least one of the following end points: the incidence of atelectasis or acute lung injury or pulmonary infections. Results Four studies (594 patients) were included. Meta-analysis using a random effects model showed a significant decrease in the incidence of atelectasis (OR=0.36; 95% CI 0.22 to 0.60; p<0.0001; I2=0%) and pulmonary infections (OR=0.30; 95% CI 0.14 to 0.68; p=0.004; I2=20%) in patients receiving protective ventilation. Ventilation with protective strategies did not reduce the incidence of acute lung injury (OR=0.40; 95% CI 0.07 to 2.15; p=0.28; I2=12%), all-cause mortality (OR=0.77; 95% CI 0.33 to 1.79; p=0.54; I2=0%), length of hospital stay (weighted mean difference (WMD)=−0.52 day, 95% CI −4.53 to 3.48 day; p=0.80; I2=63%) or length of intensive care unit stay (WMD=−0.55 day, 95% CI −2.19 to 1.09 day; p=0.51; I2=39%). Conclusions Intraoperative use of protective ventilation strategies has the potential to reduce the incidence of postoperative pulmonary complications in patients undergoing general anaesthesia. Prospective, well-designed clinical trials are warranted to confirm the beneficial effects of protective ventilation strategies in surgical patients. PMID:24961718

Early stabilizing alveolar ventilation prevents acute respiratory distress syndrome: a novel timing-based ventilatory intervention to avert lung injury.

PubMed

Roy, Shreyas; Sadowitz, Benjamin; Andrews, Penny; Gatto, Louis A; Marx, William; Ge, Lin; Wang, Guirong; Lin, Xin; Dean, David A; Kuhn, Michael; Ghosh, Auyon; Satalin, Joshua; Snyder, Kathy; Vodovotz, Yoram; Nieman, Gary; Habashi, Nader

2012-08-01

Established acute respiratory distress syndrome (ARDS) is often refractory to treatment. Clinical trials have demonstrated modest treatment effects, and mortality remains high. Ventilator strategies must be developed to prevent ARDS. Early ventilatory intervention will block progression to ARDS if the ventilator mode (1) maintains alveolar stability and (2) reduces pulmonary edema formation. Yorkshire pigs (38-45 kg) were anesthetized and subjected to a "two-hit" ischemia-reperfusion and peritoneal sepsis. After injury, animals were randomized into two groups: early preventative ventilation (airway pressure release ventilation [APRV]) versus nonpreventative ventilation (NPV) and followed for 48 hours. All animals received anesthesia, antibiotics, and fluid or vasopressor therapy as per the Surviving Sepsis Campaign. Titrated for optimal alveolar stability were the following ventilation parameters: (1) NPV group--tidal volume, 10 mL/kg + positive end-expiratory pressure - 5 cm/H2O volume-cycled mode; (2) APRV group--tidal volume, 10 to 15 mL/kg; high pressure, low pressure, time duration of inspiration (Thigh), and time duration of release phase (Tlow). Physiological data and plasma were collected throughout the 48-hour study period, followed by BAL and necropsy. APRV prevented the development of ARDS (p < 0.001 vs. NPV) by PaO₂/FIO₂ ratio. Quantitative histological scoring showed that APRV prevented lung tissue injury (p < 0.001 vs. NPV). Bronchoalveolar lavage fluid showed that APRV lowered total protein and interleukin 6 while preserving surfactant proteins A and B (p < 0.05 vs. NPV). APRV significantly lowered lung water (p < 0.001 vs. NPV). Plasma interleukin 6 concentrations were similar between groups. Early preventative mechanical ventilation with APRV blocked ARDS development, preserved surfactant proteins, and reduced pulmonary inflammation and edema despite systemic inflammation similar to NPV. These data suggest that early preventative ventilation strategies stabilizing alveoli and reducing pulmonary edema can attenuate ARDS after ischemia-reperfusion and sepsis.

Optimisation of quantitative lung SPECT applied to mild COPD: a software phantom simulation study.

PubMed

Norberg, Pernilla; Olsson, Anna; Alm Carlsson, Gudrun; Sandborg, Michael; Gustafsson, Agnetha

2015-01-01

The amount of inhomogeneities in a (99m)Tc Technegas single-photon emission computed tomography (SPECT) lung image, caused by reduced ventilation in lung regions affected by chronic obstructive pulmonary disease (COPD), is correlated to disease advancement. A quantitative analysis method, the CVT method, measuring these inhomogeneities was proposed in earlier work. To detect mild COPD, which is a difficult task, optimised parameter values are needed. In this work, the CVT method was optimised with respect to the parameter values of acquisition, reconstruction and analysis. The ordered subset expectation maximisation (OSEM) algorithm was used for reconstructing the lung SPECT images. As a first step towards clinical application of the CVT method in detecting mild COPD, this study was based on simulated SPECT images of an advanced anthropomorphic lung software phantom including respiratory and cardiac motion, where the mild COPD lung had an overall ventilation reduction of 5%. The best separation between healthy and mild COPD lung images as determined using the CVT measure of ventilation inhomogeneity and 125 MBq (99m)Tc was obtained using a low-energy high-resolution collimator (LEHR) and a power 6 Butterworth post-filter with a cutoff frequency of 0.6 to 0.7 cm(-1). Sixty-four reconstruction updates and a small kernel size should be used when the whole lung is analysed, and for the reduced lung a greater number of updates and a larger kernel size are needed. A LEHR collimator and 125 (99m)Tc MBq together with an optimal combination of cutoff frequency, number of updates and kernel size, gave the best result. Suboptimal selections of either cutoff frequency, number of updates and kernel size will reduce the imaging system's ability to detect mild COPD in the lung phantom.

Ventilation/Perfusion Positron Emission Tomography—Based Assessment of Radiation Injury to Lung

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siva, Shankar, E-mail: shankar.siva@petermac.org; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville; Hardcastle, Nicholas

2015-10-01

Purpose: To investigate {sup 68}Ga-ventilation/perfusion (V/Q) positron emission tomography (PET)/computed tomography (CT) as a novel imaging modality for assessment of perfusion, ventilation, and lung density changes in the context of radiation therapy (RT). Methods and Materials: In a prospective clinical trial, 20 patients underwent 4-dimensional (4D)-V/Q PET/CT before, midway through, and 3 months after definitive lung RT. Eligible patients were prescribed 60 Gy in 30 fractions with or without concurrent chemotherapy. Functional images were registered to the RT planning 4D-CT, and isodose volumes were averaged into 10-Gy bins. Within each dose bin, relative loss in standardized uptake value (SUV) was recorded for ventilation andmore » perfusion, and loss in air-filled fraction was recorded to assess RT-induced lung fibrosis. A dose-effect relationship was described using both linear and 2-parameter logistic fit models, and goodness of fit was assessed with Akaike Information Criterion (AIC). Results: A total of 179 imaging datasets were available for analysis (1 scan was unrecoverable). An almost perfectly linear negative dose-response relationship was observed for perfusion and air-filled fraction (r{sup 2}=0.99, P<.01), with ventilation strongly negatively linear (r{sup 2}=0.95, P<.01). Logistic models did not provide a better fit as evaluated by AIC. Perfusion, ventilation, and the air-filled fraction decreased 0.75 ± 0.03%, 0.71 ± 0.06%, and 0.49 ± 0.02%/Gy, respectively. Within high-dose regions, higher baseline perfusion SUV was associated with greater rate of loss. At 50 Gy and 60 Gy, the rate of loss was 1.35% (P=.07) and 1.73% (P=.05) per SUV, respectively. Of 8/20 patients with peritumoral reperfusion/reventilation during treatment, 7/8 did not sustain this effect after treatment. Conclusions: Radiation-induced regional lung functional deficits occur in a dose-dependent manner and can be estimated by simple linear models with 4D-V/Q PET/CT imaging. These findings may inform future studies of functional lung avoidance using V/Q PET/CT.« less

Efficiency index: a new parameter to define breathing patterns during dynamic Xe-127 ventilation studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slosman, D.; Susskind, H.; Bossuyt, A.

1986-03-01

Ventilation imaging can be improved by gating scintigraphic data with the respiratory cycle using temporal Fourier analysis (TFA) to quantify the temporal behavior of the ventilation. Sixteen consecutive images, representing equal-time increments of an average respiratory cycle, were produced by TFA in the posterior view on a pixel-by-pixel basis. An Efficiency Index (EFF), defined as the ratio of the summation of all the differences between maximum and minimum counts for each pixel to that for the entire lung during the respiratory cycle, was derived to describe the pattern of ventilation. The gated ventilation studies were carried out with Xe-127 inmore » 12 subjects: normal lung function (4), small airway disease (2), COPD (5), and restrictive disease (1). EFF for the first three harmonics correlated linearly with FEV1 (r = 0.701, p< 0.01). This approach is suggested as a very sensitive method to quantify the extent and regional distribution of airway obstruction.« less

Dynamic airway pressure-time curve profile (Stress Index): a systematic review.

PubMed

Terragni, Pierpaolo; Bussone, Guido; Mascia, Luciana

2016-01-01

The assessment of respiratory mechanics at the bedside is necessary in order to identify the most protective ventilatory strategy. Indeed in the last 20 years, adverse effects of positive ventilation to the lung structures have led to a reappraisal of the objectives of mechanical ventilation. The ventilator setting requires repeated readjustment over the period of mechanical ventilation dependency and careful respiratory monitoring to minimize the risks, preventing further injury and permitting the lung and airways healing. Among the different methods that have been proposed and validated, the analysis of dynamic P-t curve (named Stress Index, SI) represents an adequate tool available at the bedside, repeatable and, therefore, able to identify the amount of overdistension occurring in the daily clinical practice, when modifying positive end-expiratory pressure. In this review we will analyze the evidence that supports respiratory mechanics assessment at the bedside and the application of the dynamic P/t curve profile (SI) to optimize protective ventilation in patients with acute respiratory failure.

Perfluorocarbon-associated gas exchange in normal and acid-injured large sheep.

PubMed

Hernan, L J; Fuhrman, B P; Kaiser, R E; Penfil, S; Foley, C; Papo, M C; Leach, C L

1996-03-01

We hypothesized that a) perfluorocarbon-associated gas exchange could be accomplished in normal large sheep; b) the determinants of gas exchange would be similar during perfluorocarbon-associated gas exchange and conventional gas ventilation; c)in large animals with lung injury, perfluorocarbon-associated gas exchange could be used to enhance gas exchange without adverse effects on hemodynamics; and d) the large animal with lung injury could be supported with an FIO2 of <1.0 during perfluorocarbon-associated gas exchange. Prospective, observational animal study and prospective randomized, controlled animal study. An animal laboratory in a university setting. Thirty adult ewes. Five normal ewes (61.0 +/- 4.0 kg) underwent perfluorocarbon-associated gas exchange to ascertain the effects of tidal volume, end-inspiratory pressure, and positive end-expiratory pressure (PEEP) on oxygenation. Respiratory rate, tidal volume, and minute ventilation were studied to determine their effects on CO2 clearance. Sheep, weighing 58.9 +/- 8.3 kg, had lung injury induced by instilling 2 mL/kg of 0.05 Normal hydrochloric acid into the trachea. Five minutes after injury, PEEP was increased to 10 cm H2O. Ten minutes after injury, sheep with Pao2 values of <100 torr (<13.3 kPa) were randomized to continue gas ventilation (control, n=9) or to institute perfluorocarbon-associated gas exchange (n=9) by instilling 1.6 L of unoxygenated perflubron into the trachea and resuming gas ventilation. Blood gas and hemodynamic measurements were obtained throughout the 4-hr study. Both tidal volume and end-inspiratory pressure influenced oxygenation in normal sheep during perfluorocarbon-associated gas exchange. Minute ventilation determined CO2 clearance during perfluorocarbon-associated gas exchange in normal sheep. After acid aspiration lung injury, perfluorocarbon-associated gas exchange increased PaO2 and reduced intrapulmonary shunt fraction. Hypoxia and intrapulmonary shunting were unabated after injury in control animals. Hemodynamics were not influenced by the institution of perfluorocarbon-associated gas exchange. Tidal volume and end-inspiratory pressure directly influence oxygenation during perfluorocarbon-associated gas exchange in large animals. Minute ventilation influences clearance of CO2. In adult sheep with acid aspiration lung injury, perfluorocarbon-associated gas exchange at an FIO2 of <1.0 supports oxygenation and improves intrapulmonary shunting, without adverse hemodynamic effects, when compared with conventional gas ventilation.

Effects of lung protective mechanical ventilation associated with permissive respiratory acidosis on regional extra-pulmonary blood flow in experimental ARDS.

PubMed

Hering, Rudolf; Kreyer, Stefan; Putensen, Christian

2017-10-27

Lung protective mechanical ventilation with limited peak inspiratory pressure has been shown to affect cardiac output in patients with ARDS. However, little is known about the impact of lung protective mechanical ventilation on regional perfusion, especially when associated with moderate permissive respiratory acidosis. We hypothesized that lung protective mechanical ventilation with limited peak inspiratory pressure and moderate respiratory acidosis results in an increased cardiac output but unequal distribution of blood flow to the different organs of pigs with oleic-acid induced ARDS. Twelve pigs were enrolled, 3 died during instrumentation and induction of lung injury. Thus, 9 animals received pressure controlled mechanical ventilation with a PEEP of 5 cmH 2 O and limited peak inspiratory pressure (17 ± 4 cmH 2 O) versus increased peak inspiratory pressure (23 ± 6 cmH 2 O) in a crossover-randomized design and were analyzed. The sequence of limited versus increased peak inspiratory pressure was randomized using sealed envelopes. Systemic and regional hemodynamics were determined by double indicator dilution technique and colored microspheres, respectively. The paired student t-test and the Wilcoxon test were used to compare normally and not normally distributed data, respectively. Mechanical ventilation with limited inspiratory pressure resulted in moderate hypercapnia and respiratory acidosis (PaCO 2 71 ± 12 vs. 46 ± 9 mmHg, and pH 7.27 ± 0.05 vs. 7.38 ± 0.04, p < 0.001, respectively), increased cardiac output (140 ± 32 vs. 110 ± 22 ml/min/kg, p<0.05) and regional blood flow in the myocardium, brain and spinal cord, adrenal and thyroid glands, the mucosal layers of the esophagus and jejunum, the muscularis layers of the esophagus and duodenum, and the gall and urinary bladders. Perfusion of kidneys, pancreas, spleen, hepatic arterial bed, and the mucosal and muscularis blood flow to the other evaluated intestinal regions remained unchanged. In this porcine model of ARDS mechanical ventilation with limited peak inspiratory pressure resulting in moderate respiratory acidosis was associated with an increase in cardiac output. However, the better systemic blood flow was not uniformly directed to the different organs. This observation may be of clinical interest in patients, e.g. with cardiac, renal and cerebral pathologies.

TH-CD-202-09: Free-Breathing Proton MRI Functional Lung Avoidance Maps to Guide Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capaldi, D; Sheikh, K; Parraga, G

Purpose: Pulmonary functional MRI using inhaled gas contrast agents was previously investigated as a way to identify well-functioning lung in patients with NSCLC who are clinical candidates for radiotherapy. Hyperpolarized noble-gas ({sup 3}He and {sup 129}Xe) MRI has also been optimized to measure functional lung information, but for a number of reasons, the clinical translation of this approach to guide radiotherapy planning has been limited. As an alternative, free-breathing pulmonary 1H MRI using clinically available MRI systems and pulse sequences provides a non-contrast-enhanced method to generate both ventilation and perfusion maps. Free-breathing {sup 1}H MRI exploits non-rigid registration and Fouriermore » decomposition of MRI signal intensity differences (Bauman et al., MRM, 2009) that may be generated during normal tidal breathing. Here, our objective was to generate free-breathing {sup 1}H MRI ventilation and lung function avoidance maps in patients with NSCLC as a way to guide radiation therapy planning. Methods: Stage IIIA/IIIB NSCLC patients (n=8, 68±9yr) provided written informed consent to a randomized controlled clinical trial ( https://clinicaltrials.gov/ct2/show/NCT02002052 ) that aimed to compare outcomes related to image-guided versus conventional radiation therapy planning. Hyperpolarized {sup 3}He/{sup 129}Xe and dynamic free tidal-breathing {sup 1}H MRI were acquired as previously described (Capaldi et al., Acad Radiol, 2015). Non-rigid registration was performed using the modality-independent-neighbourhood-descriptor (MIND) deformable approach (Heinrich et al., Med Image Anal, 2012). Ventilation-defect-percent ({sup 3}He:VDP{sub He}, {sup 129}Xe:VDP{sub Xe}, Free-breathing-{sup 1}H:VDP{sub FB}) and the corresponding ventilation maps were compared using Pearson correlation coefficients (r) and the Dice similarity coefficient (DSC). Results: VDP{sub FB} was significantly related to VDP{sub He} (r=.71; p=.04) and VDP{sub Xe} (r=.80; p=.01) and there were also strong spatial relationships (DSC{sub He}/DSC{sub Xe}=89±3%/77±11%). Conclusion: In this proof of concept study in NSCLC patients, free-breathing {sup 1}H MRI ventilation defects were quantitatively and spatially related to inhaled-noble-gas MRI ventilation defects. Free-breathing {sup 1}H MRI measures lung function/ventilation that can be used to optimize radiotherapy planning in NSCLC patients.« less

Nebulized heparin is associated with fewer days of mechanical ventilation in critically ill patients: a randomized controlled trial.

PubMed

Dixon, Barry; Schultz, Marcus J; Smith, Roger; Fink, James B; Santamaria, John D; Campbell, Duncan J

2010-01-01

Prolonged mechanical ventilation has the potential to aggravate or initiate pulmonary inflammation and cause lung damage through fibrin deposition. Heparin may reduce pulmonary inflammation and fibrin deposition. We therefore assessed whether nebulized heparin improved lung function in patients expected to require prolonged mechanical ventilation. Fifty patients expected to require mechanical ventilation for more than 48 hours were enrolled in a double-blind randomized placebo-controlled trial of nebulized heparin (25,000 U) or placebo (normal saline) 4 or 6 hourly, depending on patient height. The study drug was continued while the patient remained ventilated to a maximum of 14 days from randomization. Nebulized heparin was not associated with a significant improvement in the primary end-point, the average daily partial pressure of oxygen to inspired fraction of oxygen ratio while mechanically ventilated, but was associated with improvement in the secondary end-point, ventilator-free days amongst survivors at day 28 (22.6 ± 4.0 versus 18.0 ± 7.1, treatment difference 4.6 days, 95% CI 0.9 to 8.3, P = 0.02). Heparin administration was not associated with any increase in adverse events. Nebulized heparin was associated with fewer days of mechanical ventilation in critically ill patients expected to require prolonged mechanical ventilation. Further trials are required to confirm these findings. The Australian Clinical Trials Registry (ACTR-12608000121369).

Validating and improving CT ventilation imaging by correlating with ventilation 4D-PET/CT using {sup 68}Ga-labeled nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kipritidis, John, E-mail: john.kipritidis@sydney.edu.au; Keall, Paul J.; Siva, Shankar

Purpose: CT ventilation imaging is a novel functional lung imaging modality based on deformable image registration. The authors present the first validation study of CT ventilation using positron emission tomography with{sup 68}Ga-labeled nanoparticles (PET-Galligas). The authors quantify this agreement for different CT ventilation metrics and PET reconstruction parameters. Methods: PET-Galligas ventilation scans were acquired for 12 lung cancer patients using a four-dimensional (4D) PET/CT scanner. CT ventilation images were then produced by applying B-spline deformable image registration between the respiratory correlated phases of the 4D-CT. The authors test four ventilation metrics, two existing and two modified. The two existing metricsmore » model mechanical ventilation (alveolar air-flow) based on Hounsfield unit (HU) change (V{sub HU}) or Jacobian determinant of deformation (V{sub Jac}). The two modified metrics incorporate a voxel-wise tissue-density scaling (ρV{sub HU} and ρV{sub Jac}) and were hypothesized to better model the physiological ventilation. In order to assess the impact of PET image quality, comparisons were performed using both standard and respiratory-gated PET images with the former exhibiting better signal. Different median filtering kernels (σ{sub m} = 0 or 3 mm) were also applied to all images. As in previous studies, similarity metrics included the Spearman correlation coefficient r within the segmented lung volumes, and Dice coefficient d{sub 20} for the (0 − 20)th functional percentile volumes. Results: The best agreement between CT and PET ventilation was obtained comparing standard PET images to the density-scaled HU metric (ρV{sub HU}) with σ{sub m} = 3 mm. This leads to correlation values in the ranges 0.22 ⩽ r ⩽ 0.76 and 0.38 ⩽ d{sub 20} ⩽ 0.68, with r{sup ¯}=0.42±0.16 and d{sup ¯}{sub 20}=0.52±0.09 averaged over the 12 patients. Compared to Jacobian-based metrics, HU-based metrics lead to statistically significant improvements in r{sup ¯} and d{sup ¯}{sub 20} (p < 0.05), with density scaled metrics also showing higher r{sup ¯} than for unscaled versions (p < 0.02). r{sup ¯} and d{sup ¯}{sub 20} were also sensitive to image quality, with statistically significant improvements using standard (as opposed to gated) PET images and with application of median filtering. Conclusions: The use of modified CT ventilation metrics, in conjunction with PET-Galligas and careful application of image filtering has resulted in improved correlation compared to earlier studies using nuclear medicine ventilation. However, CT ventilation and PET-Galligas do not always provide the same functional information. The authors have demonstrated that the agreement can improve for CT ventilation metrics incorporating a tissue density scaling, and also with increasing PET image quality. CT ventilation imaging has clear potential for imaging regional air volume change in the lung, and further development is warranted.« less

Toll-like receptor 4 knockout ameliorates neuroinflammation due to lung-brain interaction in mechanically ventilated mice.

PubMed

Chen, Ting; Chen, Chang; Zhang, Zongze; Zou, Yufeng; Peng, Mian; Wang, Yanlin

2016-08-01

Toll-like receptor 4 (TLR4) is a crucial receptor in the innate immune system, and increasing evidence supports its role in inflammation, stress, and tissue injury, including injury to the lung and brain. We aimed to investigate the effects of TLR4 on neuroinflammation due to the lung-brain interaction in mechanically ventilated mice. Male wild-type (WT) C57BL/6 and TLR4 knockout (TLR4 KO) mice were divided into three groups: (1) control group (C): spontaneous breathing; (2) anesthesia group (A): spontaneous breathing under anesthesia; and (3) mechanical ventilation group (MV): 6h of MV under anesthesia. The behavioral responses of mice were tested with fear conditioning tests. The histological changes in the lung and brain were assessed using hematoxylin-eosin (HE) staining. The level of TLR4 mRNA in tissue was measured using reverse transcription-polymerase chain reaction (RT-PCR). The levels of inflammatory cytokines were measured with an enzyme-linked immunosorbent assay (ELISA). Microgliosis, astrocytosis, and the TLR4 immunoreactivity in the hippocampus were measured by double immunofluorescence. MV mice exhibited impaired cognition, and this impairment was less severe in TLR4 KO mice than in WT mice. In WT mice, MV increased TLR4 mRNA expression in the lung and brain. MV induced mild lung injury, which was prevented in TLR4 KO mice. MV mice exhibited increased levels of inflammatory cytokines, increased microglia and astrocyte activation. Microgliosis was alleviated in TLR4 KO mice. MV mice exhibited increased TLR4 immunoreactivity, which was expressed in microglia and astrocytes. These results demonstrate that TLR4 is involved in neuroinflammation due to the lung-brain interaction and that TLR4 KO ameliorates neuroinflammation due to lung-brain interaction after prolonged MV. In addition, Administration of a TLR4 antagonist (100μg/mice) to WT mice also significantly attenuated neuroinflammation of lung-brain interaction due to prolonged MV. TLR4 antagonism may be a new and novel approach for the treatment and management of neuroinflammation in long-term mechanically ventilated patients. Copyright © 2016 Elsevier Inc. All rights reserved.

Pneumothorax (image)

MedlinePlus

... pleura and the lungs is usually very thin. Pneumothorax is the collection of air or gas in ... a lung collapse. The most common cause of pneumothorax is a breathing machine (mechanical ventilator).

Effects of hyperthermia on ventilation and metabolism during hypoxia in conscious mice.

PubMed

Iwase, Michiko; Izumizaki, Masahiko; Kanamaru, Mitsuko; Homma, Ikuo

2004-02-01

Hyperthermia and hypoxia influence ventilation and metabolism; however, their synergistic effects remain unanswered. We hypothesized that an enhancement of ventilation induced by hyperthermia is competitive with hypoxic hypometabolism. We then examined the relationship of body temperature, hypoxia, and respiration in conscious mice, measuring minute ventilation (VE), aerobic metabolism, and arterial blood gases. All parameters were measured at two different body temperatures (BTs), approximately 37 degrees C (normothermia) and 39 degrees C (hyperthermia), under both normoxia (room air inhalation) and hypoxia (7% O2 inhalation). Under normoxia, VE and O2 consumption (VO2) were lower at hyperthermia than at normothermia, and the VE-VO2 ratio remained constant. PaCO2 values were normal at both BTs under normoxia. Hypoxic gas inhalation increased VE, which reached a peak in 2 min, then decreased at both BTs. VE remained at a higher level during hyperthermia than during normothermia throughout the 10 min experiment. VO2 decreased during hypoxia at both BTs. Hypoxia increased the VE-VO2 ratio because of relatively high VE with respect to the decreased VO2, which means hyperventilation. At hypoxia under hyperthermia, serious hyperventilation occurred with a further increase in VE. The augmented ventilation may be due to the thermal stimulus and a lowered thermoregulatory set point for hypoxia. Thus hyperthermia reduces ventilation and metabolism to maintain normocapnia; as a result, thermogenesis is reduced under normoxia. Hyperthermia augments hyperventilation induced by hypoxia, leading to severe hypoxic hypocapnia. Thermal stimuli may impair the adjustment of ventilation and metabolism when O2 is limited.

3He Diffusion MRI of the Lung

PubMed Central

Conradi, Mark S.; Yablonskiy, Dmitriy A.; Woods, Jason C.; Gierada, David S.; Jacob, Richard E.; Chang, Yulin V.; Choong, Cliff K.; Sukstanskii, Alex L.; Tanoli, Tariq; Lefrak, Stephen S.; Cooper, Joel D.

2007-01-01

Rationale and Objectives MR imaging of the restricted diffusion of laser-polarized 3He gas provides unique insights into the changes in lung microstructure in emphysema. Results We discuss measurements of ventilation (spin density), mean diffusivity, and the anisotropy of diffusion, which yields the mean acinar airway radius. In addition, the use of spatially modulated longitudinal magnetization allows diffusion to be measured over longer distances and times, with sensitivity to collateral ventilation paths. Early results are also presented for spin density and diffusivity maps made with a perfluorinated inert gas, C3F8. Methods Techniques for purging and imaging excised lungs are discussed. PMID:16253852

Recommendations for mechanical ventilation of critically ill children from the Paediatric Mechanical Ventilation Consensus Conference (PEMVECC).

PubMed

Kneyber, Martin C J; de Luca, Daniele; Calderini, Edoardo; Jarreau, Pierre-Henri; Javouhey, Etienne; Lopez-Herce, Jesus; Hammer, Jürg; Macrae, Duncan; Markhorst, Dick G; Medina, Alberto; Pons-Odena, Marti; Racca, Fabrizio; Wolf, Gerhard; Biban, Paolo; Brierley, Joe; Rimensberger, Peter C

2017-12-01

Much of the common practice in paediatric mechanical ventilation is based on personal experiences and what paediatric critical care practitioners have adopted from adult and neonatal experience. This presents a barrier to planning and interpretation of clinical trials on the use of specific and targeted interventions. We aim to establish a European consensus guideline on mechanical ventilation of critically children. The European Society for Paediatric and Neonatal Intensive Care initiated a consensus conference of international European experts in paediatric mechanical ventilation to provide recommendations using the Research and Development/University of California, Los Angeles, appropriateness method. An electronic literature search in PubMed and EMBASE was performed using a combination of medical subject heading terms and text words related to mechanical ventilation and disease-specific terms. The Paediatric Mechanical Ventilation Consensus Conference (PEMVECC) consisted of a panel of 15 experts who developed and voted on 152 recommendations related to the following topics: (1) general recommendations, (2) monitoring, (3) targets of oxygenation and ventilation, (4) supportive measures, (5) weaning and extubation readiness, (6) normal lungs, (7) obstructive diseases, (8) restrictive diseases, (9) mixed diseases, (10) chronically ventilated patients, (11) cardiac patients and (12) lung hypoplasia syndromes. There were 142 (93.4%) recommendations with "strong agreement". The final iteration of the recommendations had none with equipoise or disagreement. These recommendations should help to harmonise the approach to paediatric mechanical ventilation and can be proposed as a standard-of-care applicable in daily clinical practice and clinical research.

Optimizing lung aeration at birth using a sustained inflation and positive pressure ventilation in preterm rabbits

PubMed Central

te Pas, Arjan B.; Kitchen, Marcus J.; Lee, Katie; Wallace, Megan J.; Fouras, Andreas; Lewis, Robert A.; Yagi, Naoto; Uesugi, Kentaro; Hooper, Stuart B.

2016-01-01

Background: A sustained inflation (SI) facilitates lung aeration, but the most effective pressure and duration are unknown. We investigated the effect of gestational age (GA) and airway liquid volume on the required inflation pressure and SI duration. Methods: Rabbit kittens were delivered at 27, 29, and 30 d gestation, intubated and airway liquid was aspirated. Either no liquid (control) or 30 ml/kg of liquid was returned to the airways. Lung gas volumes were measured by plethysmography and phase-contrast X-ray-imaging. Starting at 22 cmH2O, airway pressure was increased until airflow commenced and pressure was then held constant. The SI was truncated when 20 ml/kg air had entered the lung and ventilation continued with intermittent positive pressure ventilation (iPPV). Results: Higher SI pressures and longer durations were required in 27-d kittens compared to 30-d kittens. During iPPV, 27-d kittens needed higher pressures and had lower functional residual capacity (FRC) compared to 30-d kittens. Adding lung liquid increased SI duration, reduced FRC, and increased resistance and pressures during iPPV in 29- and 30-d kittens. Conclusion: Immature kittens required higher starting pressures and longer SI durations to achieve a set inflation volume. Larger airway liquid volumes adversely affected lung function during iPPV in older but not young kittens. PMID:26991259

Capnographic Parameters in Ventilated Patients: Correspondence with Airway and Lung Tissue Mechanics.

PubMed

Csorba, Zsofia; Petak, Ferenc; Nevery, Kitti; Tolnai, Jozsef; Balogh, Adam L; Rarosi, Ferenc; Fodor, Gergely H; Babik, Barna

2016-05-01

Although the mechanical status of the lungs affects the shape of the capnogram, the relations between the capnographic parameters and those reflecting the airway and lung tissue mechanics have not been established in mechanically ventilated patients. We, therefore, set out to characterize how the mechanical properties of the airways and lung tissues modify the indices obtained from the different phases of the time and volumetric capnograms and how the lung mechanical changes are reflected in the altered capnographic parameters after a cardiopulmonary bypass (CPB). Anesthetized, mechanically ventilated patients (n = 101) undergoing heart surgery were studied in a prospective consecutive cross-sectional study under the open-chest condition before and 5 minutes after CPB. Forced oscillation technique was applied to measure airway resistance (Raw), tissue damping (G), and elastance (H). Time and volumetric capnography were performed to assess parameters reflecting the phase II (SII) and phase III slopes (SIII), their transition (D2min), the dead-space indices according to Fowler, Bohr, and Enghoff and the intrapulmonary shunt. Before CPB, SII and D2min exhibited the closest (P = 0.006) associations with H (0.65 and -0.57; P < 0.0001, respectively), whereas SIII correlated most strongly (P < 0.0001) with Raw (r = 0.63; P < 0.0001). CPB induced significant elevations in Raw and G and H (P < 0.0001). These adverse mechanical changes were reflected consistently in SII, SIII, and D2min, with weaker correlations with the dead-space indices (P < 0.0001). The intrapulmonary shunt expressed as the difference between the Enghoff and Bohr dead-space parameters was increased after CPB (95% ± 5% [SEM] vs 143% ± 6%; P < 0.001). In mechanically ventilated patients, the capnographic parameters from the early phase of expiration (SII and D2min) are linked to the pulmonary elastic recoil, whereas the effect of airway patency on SIII dominates over the lung tissue stiffness. However, severe deterioration in lung resistance or elastance affects both capnogram slopes.

Effects of sevoflurane on ventilator induced lung injury in a healthy lung experimental model.

PubMed

Romero, A; Moreno, A; García, J; Sánchez, C; Santos, M; García, J

2016-01-01

Ventilator-induced lung injury (VILI) causes a systemic inflammatory response in tissues, with an increase in IL-1, IL-6 and TNF-α in blood and tissues. Cytoprotective effects of sevoflurane in different experimental models are well known, and this protective effect can also be observed in VILI. The objective of this study was to assess the effects of sevoflurane in VILI. A prospective, randomized, controlled study was designed. Twenty female rats were studied. The animals were mechanically ventilated, without sevoflurane in the control group and sevoflurane 3% in the treated group (SEV group). VILI was induced applying a maximal inspiratory pressure of 35 cmH2O for 20 min without any positive end-expiratory pressure for 20 min (INJURY time). The animals were then ventilated 30 min with a maximal inspiratory pressure of 12 cmH2O and 3 cmH2O positive end-expiratory pressure (time 30 min POST-INJURY), at which time the animals were euthanized and pathological and biomarkers studies were performed. Heart rate, invasive blood pressure, pH, PaO2, and PaCO2 were recorded. The lung wet-to-dry weight ratio was used as an index of lung edema. No differences were found in the blood gas analysis parameters or heart rate between the 2 groups. Blood pressure was statistically higher in the control group, but still within the normal clinical range. The percentage of pulmonary edema and concentrations of TNF-α and IL-6 in lung tissue in the SEV group were lower than in the control group. Sevoflurane attenuates VILI in a previous healthy lung in an experimental subclinical model in rats. Copyright © 2015 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Mitochondrial-targeted DNA repair enzyme 8-oxoguanine DNA glycosylase 1 protects against ventilator-induced lung injury in intact mice.

PubMed

Hashizume, Masahiro; Mouner, Marc; Chouteau, Joshua M; Gorodnya, Olena M; Ruchko, Mykhaylo V; Potter, Barry J; Wilson, Glenn L; Gillespie, Mark N; Parker, James C

2013-02-15

This study tested the hypothesis that oxidative mitochondrial-targeted DNA (mtDNA) damage triggered ventilator-induced lung injury (VILI). Control mice and mice infused with a fusion protein targeting the DNA repair enzyme, 8-oxoguanine-DNA glycosylase 1 (OGG1) to mitochondria were mechanically ventilated with a range of peak inflation pressures (PIP) for specified durations. In minimal VILI (1 h at 40 cmH(2)O PIP), lung total extravascular albumin space increased 2.8-fold even though neither lung wet/dry (W/D) weight ratios nor bronchoalveolar lavage (BAL) macrophage inflammatory protein (MIP)-2 or IL-6 failed to differ from nonventilated or low PIP controls. This increase in albumin space was attenuated by OGG1. Moderately severe VILI (2 h at 40 cmH(2)O PIP) produced a 25-fold increase in total extravascular albumin space, a 60% increase in W/D weight ratio and marked increases in BAL MIP-2 and IL-6, accompanied by oxidative mitochondrial DNA damage, as well as decreases in the total tissue glutathione (GSH) and GSH/GSSH ratio compared with nonventilated lungs. All of these injury indices were attenuated in OGG1-treated mice. At the highest level of VILI (2 h at 50 cmH(2)O PIP), OGG1 failed to protect against massive lung edema and BAL cytokines or against depletion of the tissue GSH pool. Interestingly, whereas untreated mice died before completing the 2-h protocol, OGG1-treated mice lived for the duration of observation. Thus mitochondrially targeted OGG1 prevented VILI over a range of ventilation times and pressures and enhanced survival in the most severely injured group. These findings support the concept that oxidative mtDNA damage caused by high PIP triggers induction of acute lung inflammation and injury.

The use of chilled condensers for the recovery of perfluorocarbon liquid in an experimental model of perfluorocarbon vapour loss during neonatal partial liquid ventilation

PubMed Central

Dunster, Kimble R; Davies, Mark W; Fraser, John F

2007-01-01

Background Perfluorocarbon (PFC) vapour in the expired gases during partial liquid ventilation should be prevented from entering the atmosphere and recovered for potential reuse. This study aimed to determine how much PFC liquid could be recovered using a conventional humidified neonatal ventilator with chilled condensers in place of the usual expiratory ventilator circuit and whether PFC liquid could be recovered when using the chilled condensers at the ventilator exhaust outlet. Methods Using a model lung, perfluorocarbon vapour loss during humidified partial liquid ventilation of a 3.5 kg infant was approximated. For each test 30 mL of FC-77 was infused into the model lung. Condensers were placed in the expiratory limb of the ventilator circuit and the amounts of PFC (FC-77) and water recovered were measured five times. This was repeated with the condensers placed at the ventilator exhaust outlet. Results When the condensers were used as the expiratory limb, the mean (± SD) volume of FC77 recovered was 16.4 mL (± 0.18 mL). When the condensers were connected to the ventilator exhaust outlet the mean (± SD) volume of FC-77 recovered was 7.6 mL (± 1.14 mL). The volume of FC-77 recovered was significantly higher when the condenser was used as an expiratory limb. Conclusion Using two series connected condensers in the ventilator expiratory line 55% of PFC liquid (FC-77) can be recovered during partial liquid ventilation without altering the function of the of the ventilator circuit. This volume of PFC recovered was just over twice that recovered with the condensers connected to the ventilator exhaust outlet. PMID:17537270

Reliability of Displayed Tidal Volume in Healthy and Surfactant-Depleted Piglets.

PubMed

Mendiondo Luedloff, A Cecilia; Thurman, Tracy L; Holt, Shirley J; Bai, Shasha; Heulitt, Mark J; Courtney, Sherry E

2016-12-01

Volutrauma has been established as the key factor in ventilator-induced lung injury and can only be avoided if tidal volume (V T ) is accurately displayed and delivered. The purpose of this study was to investigate the accuracy of displayed exhaled V T in a ventilator commonly used in small infants with or without a proximal flow sensor and using 3 methods to achieve a target V T in both a healthy and lung-injured neonatal pig model. This was a prospective animal study utilizing 8 male pigs, approximately 2.0 kg (range 1.8-2.2 kg). Intubated, sedated, neonatal pigs were studied with both healthy and injured lungs using the Servo-i ventilator. In pressure-regulated volume control, both with and without a proximal flow sensor, we used 3 methods to set V T : (1) circuit compliance compensation (CCC) on, set V T 6-8 mL/kg; (2) CCC off, calculated V T using the manufacturer's circuit compliance factor; and (3) CCC off, set V T 10-12 mL/kg to approximate a target V T of 6-8 mL/kg. Ventilator-displayed exhaled V T measurements were compared with exhaled V T measured at the airway opening by a calibrated pneumotachograph. Bland-Altman plots were constructed to show the level of agreement between the two. CCC improved accuracy and precision of displayed exhaled V T when the sensor was not used, more markedly in the lung-injured model. Without CCC, the sensor improved accuracy and precision of displayed exhaled V T , again more markedly in the lung-injured model. When the Servo-i ventilator is used in neonates, CCC or the in-line sensor should be employed due to the large positive bias and imprecision seen with CCC off and no sensor in-line. Copyright © 2016 by Daedalus Enterprises.

Identifying the heterogeneity of COPD by V/P SPECT: a new tool for improving the diagnosis of parenchymal defects and grading the severity of small airways disease.

PubMed

Bajc, M; Chen, Y; Wang, J; Li, X Y; Shen, W M; Wang, C Z; Huang, H; Lindqvist, A; He, X Y

2017-01-01

Airway obstruction and possible concomitant pulmonary diseases in COPD cannot be identified conventionally with any single diagnostic tool. We aimed to diagnose and grade COPD severity and identify pulmonary comorbidities associated with COPD with ventilation/perfusion single-photon emission computed tomography (V/P SPECT) using Technegas as the functional ventilation imaging agent. 94 COPD patients (aged 43-86 years, Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages I-IV) were examined with V/P SPECT and spirometry. Ventilation and perfusion defects were analyzed blindly according to the European guidelines. Penetration grade of Technegas in V SPECT measured the degree of obstructive small airways disease. Total preserved lung function and penetration grade of Technegas in V SPECT were assessed by V/P SPECT and compared to GOLD stages and spirometry. Signs of small airway obstruction in the ventilation SPECT images were found in 92 patients. Emphysema was identified in 81 patients. Two patients had no signs of COPD, but both of them had a pulmonary embolism, and in one of them we also suspected a lung tumor. The penetration grade of Technegas in V SPECT and total preserved lung function correlated significantly to GOLD stages ( r =0.63 and -0.60, respectively, P <0.0001). V/P SPECT identified pulmonary embolism in 30 patients (32%). A pattern typical for heart failure was present in 26 patients (28%). Parenchymal changes typical for pneumonia or lung tumor were present in several cases. V/P SPECT, using Technegas as the functional ventilation imaging agent, is a new tool to diagnose COPD and to grade its severity. Additionally, it revealed heterogeneity of COPD caused by pulmonary comorbidities. The characteristics of these comorbidities suggest their significant impact in clarifying symptoms, and also their influence on the prognosis.

Induced hypernatraemia is protective in acute lung injury.

PubMed

Bihari, Shailesh; Dixon, Dani-Louise; Lawrence, Mark D; Bersten, Andrew D

2016-06-15

Sucrose induced hyperosmolarity is lung protective but the safety of administering hyperosmolar sucrose in patients is unknown. Hypertonic saline is commonly used to produce hyperosmolarity aimed at reducing intra cranial pressure in patients with intracranial pathology. Therefore we studied the protective effects of 20% saline in a lipopolysaccharide lung injury rat model. 20% saline was also compared with other commonly used fluids. Following lipopolysaccharide-induced acute lung injury, male Sprague Dawley rats received either 20% hypertonic saline, 0.9% saline, 4% albumin, 20% albumin, 5% glucose or 20% albumin with 5% glucose, i.v. During 2h of non-injurious mechanical ventilation parameters of acute lung injury were assessed. Hypertonic saline resulted in hypernatraemia (160 (1) mmol/l, mean (SD)) maintained through 2h of ventilation, and in amelioration of lung oedema, myeloperoxidase, bronchoalveolar cell infiltrate, total soluble protein and inflammatory cytokines, and lung histological injury score, compared with positive control and all other fluids (p ≤ 0.001). Lung physiology was maintained (conserved PaO2, elastance), associated with preservation of alveolar surfactant (p ≤ 0.0001). Independent of fluid or sodium load, induced hypernatraemia is lung protective in lipopolysaccharide-induced acute lung injury. Copyright © 2016 Elsevier B.V. All rights reserved.

Changes in breath sound power spectra during experimental oleic acid-induced lung injury in pigs.

PubMed

Räsänen, Jukka; Nemergut, Michael E; Gavriely, Noam

2014-01-01

To evaluate the effect of acute lung injury on the frequency spectra of breath sounds, we made serial acoustic recordings from nondependent, midlung and dependent regions of both lungs in ten 35- to 45-kg anesthetized, intubated, and mechanically ventilated pigs during development of acute lung injury induced with intravenous oleic acid in prone or supine position. Oleic acid injections rapidly produced severe derangements in the gas exchange and mechanical properties of the lung, with an average increase in venous admixture from 16 ± 12 to 62 ± 16% (P < 0.01), and a reduction in dynamic respiratory system compliance from 25 ± 4 to 14 ± 4 ml/cmH2O (P < 0.01). A concomitant increase in sound power was seen in all lung regions (P < 0.05), predominantly in frequencies 150-800 Hz. The deterioration in gas exchange and lung mechanics correlated best with concurrent spectral changes in the nondependent lung regions. Acute lung injury increases the power of breath sounds likely secondary to redistribution of ventilation from collapsed to aerated parts of the lung and improved sound transmission in dependent, consolidated areas.

Modeling the Progression of Epithelial Leak Caused by Overdistension

PubMed Central

Hamlington, Katharine L.; Ma, Baoshun; Smith, Bradford J.; Bates, Jason H. T.

2016-01-01

Mechanical ventilation is necessary for treatment of the acute respiratory distress syndrome but leads to overdistension of the open regions of the lung and produces further damage. Although we know that the excessive stresses and strains disrupt the alveolar epithelium, we know little about the relationship between epithelial strain and epithelial leak. We have developed a computational model of an epithelial monolayer to simulate leak progression due to overdistension and to explain previous experimental findings in mice with ventilator-induced lung injury. We found a nonlinear threshold-type relationship between leak area and increasing stretch force. After the force required to initiate the leak was reached, the leak area increased at a constant rate with further increases in force. Furthermore, this rate was slower than the rate of increase in force, especially at end-expiration. Parameter manipulation changed only the leak-initiating force; leak area growth followed the same trend once this force was surpassed. These results suggest that there is a particular force (analogous to ventilation tidal volume) that must not be exceeded to avoid damage and that changing cell physical properties adjusts this threshold. This is relevant for the development of new ventilator strategies that avoid inducing further injury to the lung. PMID:26951764

Enteral omega-3 fatty acid, gamma-linolenic acid, and antioxidant supplementation in acute lung injury.

PubMed

Rice, Todd W; Wheeler, Arthur P; Thompson, B Taylor; deBoisblanc, Bennett P; Steingrub, Jay; Rock, Peter

2011-10-12

The omega-3 (n-3) fatty acids docosahexaenoic acid and eicosapentaenoic acid, along with γ-linolenic acid and antioxidants, may modulate systemic inflammatory response and improve oxygenation and outcomes in patients with acute lung injury. To determine if dietary supplementation of these substances to patients with acute lung injury would increase ventilator-free days to study day 28. The OMEGA study, a randomized, double-blind, placebo-controlled, multicenter trial conducted from January 2, 2008, through February 21, 2009. Participants were 272 adults within 48 hours of developing acute lung injury requiring mechanical ventilation whose physicians intended to start enteral nutrition at 44 hospitals in the National Heart, Lung, and Blood Institute ARDS Clinical Trials Network. All participants had complete follow-up. Twice-daily enteral supplementation of n-3 fatty acids, γ-linolenic acid, and antioxidants compared with an isocaloric control. Enteral nutrition, directed by a protocol, was delivered separately from the study supplement. Ventilator-free days to study day 28. The study was stopped early for futility after 143 and 129 patients were enrolled in the n-3 and control groups. Despite an 8-fold increase in plasma eicosapentaenoic acid levels, patients receiving the n-3 supplement had fewer ventilator-free days (14.0 vs 17.2; P = .02) (difference, -3.2 [95% CI, -5.8 to -0.7]) and intensive care unit-free days (14.0 vs 16.7; P = .04). Patients in the n-3 group also had fewer nonpulmonary organ failure-free days (12.3 vs 15.5; P = .02). Sixty-day hospital mortality was 26.6% in the n-3 group vs 16.3% in the control group (P = .054), and adjusted 60-day mortality was 25.1% and 17.6% in the n-3 and control groups, respectively (P = .11). Use of the n-3 supplement resulted in more days with diarrhea (29% vs 21%; P = .001). Twice-daily enteral supplementation of n-3 fatty acids, γ-linolenic acid, and antioxidants did not improve the primary end point of ventilator-free days or other clinical outcomes in patients with acute lung injury and may be harmful. clinicaltrials.gov Identifier: NCT00609180.

Factors associated with elevated plateau pressure in patients with acute lung injury receiving lower tidal volume ventilation.

PubMed

Prescott, Hallie C; Brower, Roy G; Cooke, Colin R; Phillips, Gary; O'Brien, James M

2013-03-01

Lung-protective ventilation with lower tidal volume and lower plateau pressure improves mortality in patients with acute lung injury and acute respiratory distress syndrome. We sought to determine the incidence of elevated plateau pressure in acute lung injury /acute respiratory distress syndrome patients receiving lower tidal volume ventilation and to determine the factors that predict elevated plateau pressure in these patients. We used data from 1398 participants in Acute Respiratory Distress Syndrome Network trials, who received lower tidal volume ventilation (≤ 6.5mL/kg predicted body weight). We considered patients with a plateau pressure greater than 30cm H2O and/or a tidal volume less than 5.5mL/kg predicted body weight on study day 1 to have "elevated plateau pressure." We used logistic regression to identify baseline clinical variables associated with elevated plateau pressure and to develop a model to predict elevated plateau pressure using a subset of 1,188 patients. We validated the model in the 210 patients not used for model development. Medical centers participating in Acute Respiratory Distress Syndrome Network clinical trials. None. Of the 1,398 patients in our study, 288 (20.6%) had elevated plateau pressure on day 1. Severity of illness indices and demographic factors (younger age, greater body mass index, and non-white race) were independently associated with elevated plateau pressure. The multivariable logistic regression model for predicting elevated plateau pressure had an area under the receiving operator characteristic curve of 0.71 for both the developmental and the validation subsets. acute lung injury patients receiving lower tidal volume ventilation often have a plateau pressure that exceeds Acute Respiratory Distress Syndrome Network goals. Race, body mass index, and severity of lung injury are each independently associated with elevated plateau pressure. Selecting a smaller initial tidal volume for non-white patients and patients with higher severity of illness may decrease the incidence of elevated plateau pressure. Prospective studies are needed to evaluate this approach.

Ventilator-associated pneumonia and ICU mortality in severe ARDS patients ventilated according to a lung-protective strategy

PubMed Central

2012-01-01

Introduction Ventilator-associated pneumonia (VAP) may contribute to the mortality associated with acute respiratory distress syndrome (ARDS). We aimed to determine the incidence, outcome, and risk factors of bacterial VAP complicating severe ARDS in patients ventilated by using a strictly standardized lung-protective strategy. Methods This prospective epidemiologic study was done in all the 339 patients with severe ARDS included in a multicenter randomized, placebo-controlled double-blind trial of cisatracurium besylate in severe ARDS patients. Patients with suspected VAP underwent bronchoalveolar lavage to confirm the diagnosis. Results Ninety-eight (28.9%) patients had at least one episode of microbiologically documented bacterial VAP, including 41 (41.8%) who died in the ICU, compared with 74 (30.7%) of the 241 patients without VAP (P = 0.05). After adjustment, age and severity at baseline, but not VAP, were associated with ICU death. Cisatracurium besylate therapy within 2 days of ARDS onset decreased the risk of ICU death. Factors independently associated with an increased risk to develop a VAP were male sex and worse admission Glasgow Coma Scale score. Tracheostomy, enteral nutrition, and the use of a subglottic secretion-drainage device were protective. Conclusions In patients with severe ARDS receiving lung-protective ventilation, VAP was associated with an increased crude ICU mortality which did not remain significant after adjustment. PMID:22524447

Method of lungs regional ventilation function assessment on the basis of continuous lung monitoring results using multi-angle electrical impedance tomography

NASA Astrophysics Data System (ADS)

Aleksanyan, Grayr; Shcherbakov, Ivan; Kucher, Artem; Sulyz, Andrew

2018-04-01

With continuous monitoring of the lungs using multi-angle electric impedance tomography method, a large array of images of impedance changes in the patient's chest cavity is accumulated. This article proposes a method for evaluating the regional ventilation function of lungs based on the results of continuous monitoring using the multi-angle electric impedance tomography method, which allows one image of the thoracic cavity to be formed on the basis of a large array of images of the impedance change in the patient's chest cavity. In the presence of pathologies in the lungs (neoplasms, fluid, pneumothorax, etc.) in these areas, air filling will be disrupted, which will be displayed on the generated image. When conducting continuous monitoring in several sections, a three-dimensional pattern of air filling of the thoracic cavity is possible.

Pulmonary deposition and disappearance of aerosolised secretory leucocyte protease inhibitor.

PubMed Central

Stolk, J.; Camps, J.; Feitsma, H. I.; Hermans, J.; Dijkman, J. H.; Pauwels, E. K.

1995-01-01

BACKGROUND--The neutrophil elastase inhibitor, secretory leucocyte protease inhibitor (SLPI), is a potential therapeutic tool in inflammatory lung diseases such as cystic fibrosis and pulmonary emphysema. The distribution and disappearance in the lung of aerosolised recombinant SLPI (rSLPI) was investigated in healthy humans and in patients with cystic fibrosis or alpha 1-antitrypsin-associated emphysema. METHODS--To distinguish aerosolised rSLPI from endogenous SLPI the recombinant inhibitor was radiolabelled with 99m-technetium (99mTc) pertechnetate. Distribution and disappearance of aerosolised 99mTc-rSLPI in the lungs were studied by gamma radiation imaging. RESULTS--The deposition of 99mTc-rSLPI in normal volunteers was homogeneous in all lung lobes, while in patients with cystic fibrosis or emphysema only well ventilated areas showed deposition of the aerosol. The disappearance rate of 99mTc-rSLPI was biexponential. The half life of the rapid phase was 0.2-2.8 hours, while that of the slow phase was more than 24 hours. CONCLUSIONS--Future aerosol therapy with rSLPI will be most beneficial for well ventilated lung tissue that needs protection against neutrophil derived elastase. It may be more difficult to neutralise the burden of elastase in poorly ventilated, highly inflamed areas as are seen in cystic fibrosis. Images PMID:7638807

Lung function in post-poliomyelitis syndrome: a cross-sectional study*

PubMed Central

de Lira, Claudio Andre Barbosa; Minozzo, Fábio Carderelli; Sousa, Bolivar Saldanha; Vancini, Rodrigo Luiz; Andrade, Marília dos Santos; Quadros, Abrahão Augusto Juviniano; Oliveira, Acary Souza Bulle; da Silva, Antonio Carlos

2013-01-01

OBJECTIVE: To compare lung function between patients with post-poliomyelitis syndrome and those with sequelae of paralytic poliomyelitis (without any signs or symptoms of post-poliomyelitis syndrome), as well as between patients with post-poliomyelitis syndrome and healthy controls. METHODS: Twenty-nine male participants were assigned to one of three groups: control; poliomyelitis (comprising patients who had had paralytic poliomyelitis but had not developed post-poliomyelitis syndrome); and post-poliomyelitis syndrome. Volunteers underwent lung function measurements (spirometry and respiratory muscle strength assessment). RESULTS: The results of the spirometric assessment revealed no significant differences among the groups except for an approximately 27% lower mean maximal voluntary ventilation in the post-poliomyelitis syndrome group when compared with the control group (p = 0.0127). Nevertheless, the maximal voluntary ventilation values for the post-poliomyelitis group were compared with those for the Brazilian population and were found to be normal. No significant differences were observed in respiratory muscle strength among the groups. CONCLUSIONS: With the exception of lower maximal voluntary ventilation, there was no significant lung function impairment in outpatients diagnosed with post-poliomyelitis syndrome when compared with healthy subjects and with patients with sequelae of poliomyelitis without post-poliomyelitis syndrome. This is an important clinical finding because it shows that patients with post-poliomyelitis syndrome can have preserved lung function. PMID:24068267

An Earth-Based Model of Microgravity Pulmonary Physiology

NASA Technical Reports Server (NTRS)

Hirschl, Ronald B.; Bull, Joseph L.; Grothberg, James B.

2004-01-01

There are currently only two practical methods of achieving micro G for experimentation: parabolic flight in an aircraft or space flight, both of which have limitations. As a result, there are many important aspects of pulmonary physiology that have not been investigated in micro G. We propose to develop an earth-based animal model of micro G by using liquid ventilation, which will allow us to fill the lungs with perfluorocarbon, and submersing the animal in water such that the density of the lungs is the same as the surrounding environment. By so doing, we will eliminate the effects of gravity on respiration. We will first validate the model by comparing measures of pulmonary physiology, including cardiac output, central venous pressures, lung volumes, and pulmonary mechanics, to previous space flight and parabolic flight measurements. After validating the model, we will investigate the impact of micro G on aspects of lung physiology that have not been previously measured. These will include pulmonary blood flow distribution, ventilation distribution, pulmonary capillary wedge pressure, ventilation-perfusion matching, and pleural pressures and flows. We expect that this earth-based model of micro G will enhance our knowledge and understanding of lung physiology in space which will increase in importance as space flights increase in time and distance.

Function of the Dräger Oxylog ventilator at high altitude.

PubMed

Thomas, G; Brimacombe, J

1994-06-01

We have assessed the performance of the Dräger Oxylog ventilator at high altitude using a decompression chamber and a lung simulator set to mimic the normal and non-compliant lung. In the normal lung, tidal volume increased by 28% at 2040 metres and by 106% at 9120 metres. A lesser change, but in the opposite direction, occurred in respiratory rate. The net effect was a linear increase in minute volume with altitude. At 2040 and 9144 metres minute volume increased by 13% and by 45%, and rate decreased by 10% and 30% respectively. In the abnormal lung stimulation, similar, but slightly less marked, changes occurred in all variables. These changes are of sufficient magnitude to require frequent observation of tidal volume and respiratory rate during aircraft ascent and descent.