Automatic control of tracheal tube cuff pressure in ventilated patients in semirecumbent position: a randomized trial.

PubMed

Valencia, Mauricio; Ferrer, Miquel; Farre, Ramon; Navajas, Daniel; Badia, Joan Ramon; Nicolas, Josep Maria; Torres, Antoni

2007-06-01

The aspiration of subglottic secretions colonized by bacteria pooled around the tracheal tube cuff due to inadvertent deflation (<20 cm H2O) of the cuff plays a relevant role in the pathogenesis of ventilator-associated pneumonia. We assessed the efficacy of an automatic, validated device for the continuous regulation of tracheal tube cuff pressure in preventing ventilator-associated pneumonia. Prospective randomized controlled trial. Respiratory intensive care unit and general medical intensive care unit. One hundred and forty-two mechanically ventilated patients (age, 64 +/- 17 yrs; Acute Physiology and Chronic Health Evaluation II score, 18 +/- 6) without pneumonia or aspiration at admission. Within 24 hrs of intubation, patients were randomly allocated to undergo continuous regulation of the cuff pressure with the automatic device (n = 73) or routine care of the cuff pressure (control group, n = 69). Patients remained in a semirecumbent position in bed. The primary end point variable was the incidence of ventilator-associated pneumonia. Main causes for intubation were decreased consciousness (43, 30%) and exacerbation of chronic respiratory diseases (38, 27%). Cuff pressure <20 cm H2O was more frequently observed in the control than the automatic group (45.3 vs. 0.7% determinations, p < .001). However, the rate of ventilator-associated pneumonia with clinical criteria (16, 22% vs. 20, 29%) and microbiological confirmation (11, 15% vs. 10, 15%), the distribution of early and late onset, the causative microorganisms, and intensive care unit (20, 27% vs. 16, 23%) and hospital mortality (30, 41% vs. 23, 33%) were similar for the automatic and control groups, respectively. Cuff pressure is better controlled with the automatic device. However, it did not result in additional benefits to the semirecumbent position in preventing ventilator-associated pneumonia.

Real-time detection of gastric insufflation related to facemask pressure-controlled ventilation using ultrasonography of the antrum and epigastric auscultation in nonparalyzed patients: a prospective, randomized, double-blind study.

PubMed

Bouvet, Lionel; Albert, Marie-Laure; Augris, Caroline; Boselli, Emmanuel; Ecochard, René; Rabilloud, Muriel; Chassard, Dominique; Allaouchiche, Bernard

2014-02-01

The authors sought to determine the level of inspiratory pressure minimizing the risk of gastric insufflation while providing adequate pulmonary ventilation. The primary endpoint was the increase in incidence of gastric insufflation detected by ultrasonography of the antrum while inspiratory pressure for facemask pressure-controlled ventilation increased from 10 to 25 cm H2O. In this prospective, randomized, double-blind study, patients were allocated to one of the four groups (P10, P15, P20, and P25) defined by the inspiratory pressure applied during controlled-pressure ventilation: 10, 15, 20, and 25 cm H2O. Anesthesia was induced using propofol and remifentanil; no neuromuscular-blocking agent was administered. Once loss of eyelash reflex occurred, facemask ventilation was started for a 2-min period while gastric insufflation was detected by auscultation and by real-time ultrasonography of the antrum. The cross-sectional antral area was measured using ultrasonography before and after facemask ventilation. Respiratory parameters were recorded. Sixty-seven patients were analyzed. The authors registered statistically significant increases in incidences of gastric insufflation with inspiratory pressure, from 0% (group P10) to 41% (group P25) according to auscultation, and from 19 to 59% according to ultrasonography. In groups P20 and P25, detection of gastric insufflation by ultrasonography was associated with a statistically significant increase in the antral area. Lung ventilation was insufficient for group P10. Inspiratory pressure of 15 cm H2O allowed for reduced occurrence of gastric insufflation with proper lung ventilation during induction of anesthesia with remifentanil and propofol in nonparalyzed and nonobese patients. (Anesthesiology 2014; 120:326-34).

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.

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

The comparison of manual and LabVIEW-based fuzzy control on mechanical ventilation.

PubMed

Guler, Hasan; Ata, Fikret

2014-09-01

The aim of this article is to develop a knowledge-based therapy for management of rats with respiratory distress. A mechanical ventilator was designed to achieve this aim. The designed ventilator is called an intelligent mechanical ventilator since fuzzy logic was used to control the pneumatic equipment according to the rat's status. LabVIEW software was used to control all equipments in the ventilator prototype and to monitor respiratory variables in the experiment. The designed ventilator can be controlled both manually and by fuzzy logic. Eight female Wistar-Albino rats were used to test the designed ventilator and to show the effectiveness of fuzzy control over manual control on pressure control ventilation mode. The anesthetized rats were first ventilated for 20 min manually. After that time, they were ventilated for 20 min by fuzzy logic. Student's t-test for p < 0.05 was applied to the measured minimum, maximum and mean peak inspiration pressures to analyze the obtained results. The results show that there is no statistical difference in the rat's lung parameters before and after the experiments. It can be said that the designed ventilator and developed knowledge-based therapy support artificial respiration of living things successfully. © IMechE 2014.

A bench study of intensive-care-unit ventilators: new versus old and turbine-based versus compressed gas-based ventilators

PubMed Central

Thille, Arnaud W.; Lyazidi, Aissam; Richard, Jean-Christophe M.; Galia, Fabrice; Brochard, Laurent

2009-01-01

Objective To compare 13 commercially available, new-generation, intensive-care-unit (ICU) ventilators regarding trigger function, pressurization capacity during pressure-support ventilation (PSV), accuracy of pressure measurements and expiratory resistance. Design and Setting Bench study at a research laboratory in a university hospital. Material Four turbine-based ventilators and nine conventional servo-valve compressed-gas ventilators were tested using a two-compartment lung model. Results Three levels of effort were simulated. Each ventilator was evaluated at four PSV levels (5, 10, 15, and 20 cm H2O), with and without positive end-expiratory pressure (5 cm H2O, Trigger function was assessed as the time from effort onset to detectable pressurization. Pressurization capacity was evaluated using the airway pressure-time product computed as the net area under the pressure-time curve over the first 0.3 s after inspiratory effort onset. Expiratory resistance was evaluated by measuring trapped volume in controlled ventilation. Significant differences were found across the ventilators, with a range of triggering-delay from 42 ms to 88 ms for all conditions averaged (P<.001). Under difficult conditions, the triggering delay was longer than 100 ms and the pressurization was poor with five ventilators at PSV5 and three at PSV10, suggesting an inability to unload patient’s effort. On average, turbine-based ventilators performed better than conventional ventilators, which showed no improvement compared to a 2000 bench comparison. Conclusion Technical performances of trigger function, pressurization capacity and expiratory resistance vary considerably across new-generation ICU ventilators. ICU ventilators seem to have reached a technical ceiling in recent years, and some ventilators still perform inadequately. PMID:19352622

A bench study of intensive-care-unit ventilators: new versus old and turbine-based versus compressed gas-based ventilators.

PubMed

Thille, Arnaud W; Lyazidi, Aissam; Richard, Jean-Christophe M; Galia, Fabrice; Brochard, Laurent

2009-08-01

To compare 13 commercially available, new-generation, intensive-care-unit (ICU) ventilators in terms of trigger function, pressurization capacity during pressure-support ventilation (PSV), accuracy of pressure measurements, and expiratory resistance. Bench study at a research laboratory in a university hospital. Four turbine-based ventilators and nine conventional servo-valve compressed-gas ventilators were tested using a two-compartment lung model. Three levels of effort were simulated. Each ventilator was evaluated at four PSV levels (5, 10, 15, and 20 cm H2O), with and without positive end-expiratory pressure (5 cm H2O). Trigger function was assessed as the time from effort onset to detectable pressurization. Pressurization capacity was evaluated using the airway pressure-time product computed as the net area under the pressure-time curve over the first 0.3 s after inspiratory effort onset. Expiratory resistance was evaluated by measuring trapped volume in controlled ventilation. Significant differences were found across the ventilators, with a range of triggering delays from 42 to 88 ms for all conditions averaged (P < 0.001). Under difficult conditions, the triggering delay was longer than 100 ms and the pressurization was poor for five ventilators at PSV5 and three at PSV10, suggesting an inability to unload patient's effort. On average, turbine-based ventilators performed better than conventional ventilators, which showed no improvement compared to a bench comparison in 2000. Technical performance of trigger function, pressurization capacity, and expiratory resistance differs considerably across new-generation ICU ventilators. ICU ventilators seem to have reached a technical ceiling in recent years, and some ventilators still perform inadequately.

Software for real-time control of a tidal liquid ventilator.

PubMed

Heckman, J L; Hoffman, J; Shaffer, T H; Wolfson, M R

1999-01-01

The purpose of this project was to develop and test computer software and control algorithms designed to operate a tidal liquid ventilator. The tests were executed on a 90-MHz Pentium PC with 16 MB RAM and a prototype liquid ventilator. The software was designed using Microsoft Visual C++ (Ver. 5.0) and the Microsoft Foundation Classes. It uses a graphic user interface, is multithreaded, runs in real time, and has a built-in simulator that facilitates user education in liquid-ventilation principles. The operator can use the software to specify ventilation parameters such as the frequency of ventilation, the tidal volume, and the inspiratory-expiratory time ratio. Commands are implemented via control of the pump speed and by setting the position of two two-way solenoid-controlled valves. Data for use in monitoring and control are gathered by analog-to-digital conversion. Control strategies are implemented to maintain lung volumes and airway pressures within desired ranges, according to limits set by the operator. Also, the software allows the operator to define the shape of the flow pulse during inspiration and expiration, and to optimize perfluorochemical liquid transfer while minimizing airway pressures and maintaining the desired tidal volume. The operator can stop flow during inspiration and expiration to measure alveolar pressures. At the end of expiration, the software stores all user commands and 30 ventilation parameters into an Excel spreadsheet for later review and analysis. Use of these software and control algorithms affords user-friendly operation of a tidal liquid ventilator while providing precise control of ventilation parameters.

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.

Randomised controlled cross-over comparison of continuous positive airway pressure through the Hamilton Galileo ventilator with a Dräger CF 800 device.

PubMed

Sutton, P J; Perkins, C L; Giles, S P; McAuley, D F; Gao, F

2005-01-01

In this controlled, randomised cross-over trial on 26 intensive care patients, we compared the effects on haemodynamic and respiratory profiles of continuous positive airway pressure delivered through the Hamilton Galileo ventilator or a Drager CF 800 device. We also compared the nursing time saved using the two approaches when weaning patients from mechanical ventilation. We did not find significant differences in haemodynamics, respiratory rate, physiological dead space, oxygen saturation and carbon dioxide production between the continuous positive airway pressure generated by the Galileo and Drager machines. However, there was a 10-fold reduction in nursing time using the Galileo ventilator compared with the Drager generator. We conclude that continuous positive airway pressure delivered through the Galileo ventilator is as efficient as a Drager device but consumes less nursing time.

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.

A historical perspective on ventilator management.

PubMed

Shapiro, B A

1994-02-01

Paralysis via neuromuscular blockade in ICU patients requires mechanical ventilation. This review historically addresses the technological advances and scientific information upon which ventilatory management concepts are based, with special emphasis on the influence such concepts have had on the use of neuromuscular blocking agents. Specific reference is made to the scientific information and technological advances leading to the newer concepts of ventilatory management. Information from > 100 major studies in the peer-reviewed medical literature, along with the author's 25 yrs of clinical experience and academic involvement in acute respiratory care is presented. Nomenclature related to ventilatory management is specifically defined and consistently utilized to present and interpret the data. Pre-1970 ventilatory management is traced from the clinically unacceptable pressure-limited devices to the reliable performance of volume-limited ventilators. The scientific data and rationale that led to the concept of relatively large tidal volume delivery are reviewed in the light of today's concerns regarding alveolar overdistention, control-mode dyssynchrony, and auto-positive end-expiratory pressure. Also presented are the post-1970 scientific rationales for continuous positive airway pressure/positive end-expiratory pressure therapy, avoidance of alveolar hyperxia, and partial ventilatory support techniques (intermittent mandatory ventilation/synchronized intermittent mandatory ventilation). The development of pressure-support devices is discussed and the capability of pressure-control techniques is presented. The rationale for more recent concepts of total ventilatory support to avoid ventilator-induced lung injury is presented. The traditional techniques utilizing volume-preset ventilators with relatively large tidal volumes remain valid and desirable for the vast majority of patients requiring mechanical ventilation. Neuromuscular blockade is best avoided in these patients. However, adequate analgesia, amnesia, and sedation are required. For patients with severe lung disease, alveolar overdistention and hyperoxia should be avoided and may be best accomplished by total ventilatory support techniques, such as pressure control. Total ventilatory support requires neuromuscular blockade and may not provide eucapnic ventilation.

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.

Potential Acceptability of a Pediatric Ventilator Management Computer Protocol.

PubMed

Sward, Katherine A; Newth, Christopher J L; 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; Doctor, Allan; Dean, J Michael; Holobkov, Richard; Jenkins, Tammara L; Nicholson, Carol E

2017-11-01

To examine issues regarding the granularity (size/scale) and potential acceptability of recommendations in a ventilator management protocol for children with pediatric acute respiratory distress syndrome. Survey/questionnaire. The eight PICUs in the Collaborative Pediatric Critical Care Research Network. One hundred twenty-two physicians (attendings and fellows). None. We used an online questionnaire to examine attitudes and assessed recommendations with 50 clinical scenarios. Overall 80% of scenario recommendations were accepted. Acceptance did not vary by provider characteristics but did vary by ventilator mode (high-frequency oscillatory ventilation 83%, pressure-regulated volume control 82%, pressure control 75%; p = 0.002) and variable adjusted (ranging from 88% for peak inspiratory pressure and 86% for FIO2 changes to 69% for positive end-expiratory pressure changes). Acceptance did not vary based on child size/age. There was a preference for smaller positive end-expiratory pressure changes but no clear granularity preference for other variables. Although overall acceptance rate for scenarios was good, there was little consensus regarding the size/scale of ventilator setting changes for children with pediatric acute respiratory distress syndrome. An acceptable protocol could support robust evaluation of ventilator management strategies. Further studies are needed to determine if adherence to an explicit protocol leads to better outcomes.

[The numerical simulation of the internal flow field inside the pressure generator of a continuous positive airway pressure ventilator].

PubMed

Cheng, Yunzhang; Zhu, Lihua; Zhang, Weiguo; Wu, Wenquan

2011-12-01

The problem of noise in ventilator has always been an important topic to study in the development of the ventilator. A great number of data are showing that there are still large gaps of research and application levels in noise control of the ventilator between China and some more advanced foreign countries. In this study, with cooperation of the Shanghai Medical Equipment Limited Liability Company, we used the computational fluid dynamics (CFD), software FLUENT, adopted the standard k-epsilon turbulence model and the SIMPLE algorithm to simulate the inner flow field of the continuous positive airway pressure (CPAP) ventilator's pressure generator. After a detailed analysis, we figured out that there are several deficiencies in this ventilator, like local reflow in volute, uneven velocity distribution and local negative pressure in inlet of the impeller, which easily lead to noise and affect the ventilator's performances. So, it needs to be improved to a certain extent.

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.

Association between driving pressure and development of postoperative pulmonary complications in patients undergoing mechanical ventilation for general anaesthesia: a meta-analysis of individual patient data.

PubMed

Neto, Ary Serpa; Hemmes, Sabrine N T; Barbas, Carmen S V; Beiderlinden, Martin; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; El-Tahan, Mohamed R; Ghamdi, Abdulmohsin A Al; Günay, Ersin; Jaber, Samir; Kokulu, Serdar; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Maslow, Andrew D; Memtsoudis, Stavros G; Reis Miranda, Dinis; Moine, Pierre; Ng, Thomas; Paparella, Domenico; Ranieri, V Marco; Scavonetto, Federica; Schilling, Thomas; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N; Wolthuis, Esther K; Wrigge, Hermann; Amato, Marcelo B P; Costa, Eduardo L V; de Abreu, Marcelo Gama; Pelosi, Paolo; Schultz, Marcus J

2016-04-01

Protective mechanical ventilation strategies using low tidal volume or high levels of positive end-expiratory pressure (PEEP) improve outcomes for patients who have had surgery. The role of the driving pressure, which is the difference between the plateau pressure and the level of positive end-expiratory pressure is not known. We investigated the association of tidal volume, the level of PEEP, and driving pressure during intraoperative ventilation with the development of postoperative pulmonary complications. We did a meta-analysis of individual patient data from randomised controlled trials of protective ventilation during general anesthaesia for surgery published up to July 30, 2015. The main outcome was development of postoperative pulmonary complications (postoperative lung injury, pulmonary infection, or barotrauma). We included data from 17 randomised controlled trials, including 2250 patients. Multivariate analysis suggested that driving pressure was associated with the development of postoperative pulmonary complications (odds ratio [OR] for one unit increase of driving pressure 1·16, 95% CI 1·13-1·19; p<0·0001), whereas we detected no association for tidal volume (1·05, 0·98-1·13; p=0·179). PEEP did not have a large enough effect in univariate analysis to warrant inclusion in the multivariate analysis. In a mediator analysis, driving pressure was the only significant mediator of the effects of protective ventilation on development of pulmonary complications (p=0·027). In two studies that compared low with high PEEP during low tidal volume ventilation, an increase in the level of PEEP that resulted in an increase in driving pressure was associated with more postoperative pulmonary complications (OR 3·11, 95% CI 1·39-6·96; p=0·006). In patients having surgery, intraoperative high driving pressure and changes in the level of PEEP that result in an increase of driving pressure are associated with more postoperative pulmonary complications. However, a randomised controlled trial comparing ventilation based on driving pressure with usual care is needed to confirm these findings. None. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

[The effect of positive pressure ventilation combined with diaphragm pacing on respiratory mechanics in patients with respiratory failure].

PubMed

Deng, Yi-Jun; Ji, You-Lin; Chen, Lan-Ping; Jin, Qin

2011-04-01

To observe the effects of combining positive pressure ventilation with diaphragm pacing on respiratory mechanics in patients with respiratory failure. Twenty patients with central respiratory failure were studied with cohorts. The effects on respiratory mechanics were respectively observed in patients in control group, in whom ventilation by positive pressure only, and patients in experimental group in whom ventilation was instituted by combining positive pressure ventilation with diaphragm pacing. Compared with control group, mean airway pressure (Paw, cm H(2)O, 1 cm H(2)O= 0.098 kPa) and plateau pressure (Pplat, cm H(2)O) were significantly decreased in experimental group (Paw: 6.1±1.3 vs. 7.3±1.8; Pplat: 10.4±2.5 vs. 12.1±2.6, both P<0.05), while the negative value of peak esophageal pressure (P(PEAK ES) , cm H(2)O), the negative value of the difference between peak and basic esophageal pressure (dP(ES), cm H(2)O), transpulmonary pressure at end of inspiration hold (Ptp plat, cm H(2)O ), static compliance (Cst, ml/cm H(2)O) were significantly increased in experimental group (P(PEAK ES): -8.3± 1.9 vs. -3.2±1.4; dP(ES) : -11.2±2.6 vs. -8.2±2.2; Ptp plat: 23.6±3.8 vs. 15.6±3.1; Cst: 52.7±8.2 vs. 48.3±7.2, all P<0.05). No differences were found in airway resistance (Raw, cm H(2)O×L(-1) ×s(-1) ) and lung resistance (R(L), cm H(2)O×L(-1) ×s(-1) ) between experimental group and control group (Raw: 2.1±0.5 vs. 2.3±0.4; R(L): 2.9±0.6 vs. 3.1±0.5, both P>0.05). Work of breath by patient (WOBp, J/L) was significantly increased and work of breath by ventilator (WOBv, J/L) was significantly decreased in experimental group compared with control group (WOBp: 0.18±0.03 vs. 0; WOBv: 0.31±0.07 vs. 0.53±0.11, both P<0.05). Compared with positive pressure ventilation , positive pressure ventilation combined with diaphragm pacing can decrease the Paw, increase intrathoracic negative pressure, transpulmonary pressure, and Cst, and decrease WOBv, while there is no effect on Raw and R(L).

Modes of mechanical ventilation for the operating room.

PubMed

Ball, Lorenzo; Dameri, Maddalena; Pelosi, Paolo

2015-09-01

Most patients undergoing surgical procedures need to be mechanically ventilated, because of the impact of several drugs administered at induction and during maintenance of general anaesthesia on respiratory function. Optimization of intraoperative mechanical ventilation can reduce the incidence of post-operative pulmonary complications and improve the patient's outcome. Preoxygenation at induction of general anaesthesia prolongs the time window for safe intubation, reducing the risk of hypoxia and overweighs the potential risk of reabsorption atelectasis. Non-invasive positive pressure ventilation delivered through different interfaces should be considered at the induction of anaesthesia morbidly obese patients. Anaesthesia ventilators are becoming increasingly sophisticated, integrating many functions that were once exclusive to intensive care. Modern anaesthesia machines provide high performances in delivering the desired volumes and pressures accurately and precisely, including assisted ventilation modes. Therefore, the physicians should be familiar with the potential and pitfalls of the most commonly used intraoperative ventilation modes: volume-controlled, pressure-controlled, dual-controlled and assisted ventilation. Although there is no clear evidence to support the advantage of any one of these ventilation modes over the others, protective mechanical ventilation with low tidal volume and low levels of positive end-expiratory pressure (PEEP) should be considered in patients undergoing surgery. The target tidal volume should be calculated based on the predicted or ideal body weight rather than on the actual body weight. To optimize ventilation monitoring, anaesthesia machines should include end-inspiratory and end-expiratory pause as well as flow-volume loop curves. The routine administration of high PEEP levels should be avoided, as this may lead to haemodynamic impairment and fluid overload. Higher PEEP might be considered during surgery longer than 3 h, laparoscopy in the Trendelenburg position and in patients with body mass index >35 kg/m(2). Large randomized trials are warranted to identify subgroups of patients and the type of surgery that can potentially benefit from specific ventilation modes or ventilation settings. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Protective mechanical ventilation in United Kingdom critical care units: A multicentre audit

PubMed Central

Martin, Matthew J; Richardson, Neil; Bourdeaux, Christopher P

2016-01-01

Lung protective ventilation is becoming increasingly used for all critically ill patients being mechanically ventilated on a mandatory ventilator mode. Compliance with the universal application of this ventilation strategy in intensive care units in the United Kingdom is unknown. This 24-h audit of ventilation practice took place in 16 intensive care units in two regions of the United Kingdom. The mean tidal volume for all patients being ventilated on a mandatory ventilator mode was 7.2(±1.4) ml kg−1 predicted body weight and overall compliance with low tidal volume ventilation (≤6.5 ml kg−1 predicted body weight) was 34%. The mean tidal volume for patients ventilated with volume-controlled ventilation was 7.0(±1.2) ml kg−1 predicted body weight and 7.9(±1.8) ml kg−1 predicted body weight for pressure-controlled ventilation (P < 0.0001). Overall compliance with recommended levels of positive end-expiratory pressure was 72%. Significant variation in practice existed both at a regional and individual unit level. PMID:28979556

Protective mechanical ventilation in United Kingdom critical care units: A multicentre audit.

PubMed

Newell, Christopher P; Martin, Matthew J; Richardson, Neil; Bourdeaux, Christopher P

2017-05-01

Lung protective ventilation is becoming increasingly used for all critically ill patients being mechanically ventilated on a mandatory ventilator mode. Compliance with the universal application of this ventilation strategy in intensive care units in the United Kingdom is unknown. This 24-h audit of ventilation practice took place in 16 intensive care units in two regions of the United Kingdom. The mean tidal volume for all patients being ventilated on a mandatory ventilator mode was 7.2(±1.4) ml kg -1 predicted body weight and overall compliance with low tidal volume ventilation (≤6.5 ml kg -1 predicted body weight) was 34%. The mean tidal volume for patients ventilated with volume-controlled ventilation was 7.0(±1.2) ml kg -1 predicted body weight and 7.9(±1.8) ml kg -1 predicted body weight for pressure-controlled ventilation ( P  < 0.0001). Overall compliance with recommended levels of positive end-expiratory pressure was 72%. Significant variation in practice existed both at a regional and individual unit level.

Right ventricular function during one-lung ventilation: effects of pressure-controlled and volume-controlled ventilation.

PubMed

Al Shehri, Abdullah M; El-Tahan, Mohamed R; Al Metwally, Roshdi; Qutub, Hatem; El Ghoneimy, Yasser F; Regal, Mohamed A; Zien, Haytham

2014-08-01

To test the effects of pressure-controlled (PCV) and volume-controlled (VCV) ventilation during one-lung ventilation (OLV) for thoracic surgery on right ventricular (RV) function. A prospective, randomized, double-blind, controlled, crossover study. A single university hospital. Fourteen pairs of consecutive patients scheduled for elective thoracotomy. Patients were assigned randomly to ventilate the dependent lung with PCV or VCV mode, each in a randomized crossover order using tidal volume of 6 mL/kg, I: E ratio 1: 2.5, positive end-expiratory pressure (PEEP) of 5 cm H2O and respiratory rate adjusted to maintain normocapnia. Intraoperative changes in RV function (systolic and early diastolic tricuspid annular velocity (TAV), end-systolic volume (ESV), end-diastolic volume (EDV) and fractional area changes (FAC)), airway pressures, compliance and oxygenation index were recorded. The use of PCV during OLV resulted in faster systolic (10.1±2.39 vs. 5.8±1.67 cm/s, respectively), diastolic TAV (9.2±1.99 vs. 4.6±1.42 cm/s, respectively) (p<0.001) and compliance and lower ESV, EDV and airway pressures (p<0.05) than during the use of VCV. Oxygenation indices were similar during the use of VCV and PCV. The use of PCV offers more improved RV function than the use of VCV during OLV for open thoracotomy. These results apply specifically to younger patients with good ventricular and pulmonary functions. © 2014 Elsevier Inc. All rights reserved.

Lung ventilation strategies for acute respiratory distress syndrome: a systematic review and network meta-analysis

PubMed Central

Wang, Changsong; Wang, Xiaoyang; Chi, Chunjie; Guo, Libo; Guo, Lei; Zhao, Nana; Wang, Weiwei; Pi, Xin; Sun, Bo; Lian, Ailing; Shi, Jinghui; Li, Enyou

2016-01-01

To identify the best lung ventilation strategy for acute respiratory distress syndrome (ARDS), we performed a network meta-analysis. The Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, CINAHL, and the Web of Science were searched, and 36 eligible articles were included. Compared with higher tidal volumes with FiO2-guided lower positive end-expiratory pressure [PEEP], the hazard ratios (HRs) for mortality were 0.624 (95% confidence interval (CI) 0.419–0.98) for lower tidal volumes with FiO2-guided lower PEEP and prone positioning and 0.572 (0.34–0.968) for pressure-controlled ventilation with FiO2-guided lower PEEP. Lower tidal volumes with FiO2-guided higher PEEP and prone positioning had the greatest potential to reduce mortality, and the possibility of receiving the first ranking was 61.6%. Permissive hypercapnia, recruitment maneuver, and low airway pressures were most likely to be the worst in terms of all-cause mortality. Compared with higher tidal volumes with FiO2-guided lower PEEP, pressure-controlled ventilation with FiO2-guided lower PEEP and lower tidal volumes with FiO2-guided lower PEEP and prone positioning ventilation are associated with lower mortality in ARDS patients. Lower tidal volumes with FiO2-guided higher PEEP and prone positioning ventilation and lower tidal volumes with pressure-volume (P–V) static curve-guided individual PEEP are potential optimal strategies for ARDS patients. PMID:26955891

Actual performance of mechanical ventilators in ICU: a multicentric quality control study.

PubMed

Govoni, Leonardo; Dellaca', Raffaele L; Peñuelas, Oscar; Bellani, Giacomo; Artigas, Antonio; Ferrer, Miquel; Navajas, Daniel; Pedotti, Antonio; Farré, Ramon

2012-01-01

Even if the performance of a given ventilator has been evaluated in the laboratory under very well controlled conditions, inappropriate maintenance and lack of long-term stability and accuracy of the ventilator sensors may lead to ventilation errors in actual clinical practice. The aim of this study was to evaluate the actual performances of ventilators during clinical routines. A resistance (7.69 cmH(2)O/L/s) - elastance (100 mL/cmH(2)O) test lung equipped with pressure, flow, and oxygen concentration sensors was connected to the Y-piece of all the mechanical ventilators available for patients in four intensive care units (ICUs; n = 66). Ventilators were set to volume-controlled ventilation with tidal volume = 600 mL, respiratory rate = 20 breaths/minute, positive end-expiratory pressure (PEEP) = 8 cmH(2)O, and oxygen fraction = 0.5. The signals from the sensors were recorded to compute the ventilation parameters. The average ± standard deviation and range (min-max) of the ventilatory parameters were the following: inspired tidal volume = 607 ± 36 (530-723) mL, expired tidal volume = 608 ± 36 (530-728) mL, peak pressure = 20.8 ± 2.3 (17.2-25.9) cmH(2)O, respiratory rate = 20.09 ± 0.35 (19.5-21.6) breaths/minute, PEEP = 8.43 ± 0.57 (7.26-10.8) cmH(2)O, oxygen fraction = 0.49 ± 0.014 (0.41-0.53). The more error-prone parameters were the ones related to the measure of flow. In several cases, the actual delivered mechanical ventilation was considerably different from the set one, suggesting the need for improving quality control procedures for these machines.

The growing role of noninvasive ventilation in patients requiring prolonged mechanical ventilation.

PubMed

Hess, Dean R

2012-06-01

For many patients with chronic respiratory failure requiring ventilator support, noninvasive ventilation (NIV) is preferable to invasive support by tracheostomy. Currently available evidence does not support the use of nocturnal NIV in unselected patients with stable COPD. Several European studies have reported benefit for high intensity NIV, in which setting of inspiratory pressure and respiratory rate are selected to achieve normocapnia. There have also been studies reporting benefit for the use of NIV as an adjunct to exercise training. NIV may be useful as an adjunct to airway clearance techniques in patients with cystic fibrosis. Accumulating evidence supports the use of NIV in patients with obesity hypoventilation syndrome. There is considerable observational evidence supporting the use of NIV in patients with chronic respiratory failure related to neuromuscular disease, and one randomized controlled trial reported that the use of NIV was life-prolonging in patients with amyotrophic lateral sclerosis. A variety of interfaces can be used to provide NIV in patients with stable chronic respiratory failure. The mouthpiece is an interface that is unique in this patient population, and has been used with success in patients with neuromuscular disease. Bi-level pressure ventilators are commonly used for NIV, although there are now a new generation of intermediate ventilators that are portable, have a long battery life, and can be used for NIV and invasive applications. Pressure support ventilation, pressure controlled ventilation, and volume controlled ventilation have been used successfully for chronic applications of NIV. New modes have recently become available, but their benefits await evidence to support their widespread use. The success of NIV in a given patient population depends on selection of an appropriate patient, selection of an appropriate interface, selection of an appropriate ventilator and ventilator settings, the skills of the clinician, the motivation of the patient, and the support of the family. 2012 Daedalus Enterprises

Anaesthesia ventilators.

PubMed

Jain, Rajnish K; Swaminathan, Srinivasan

2013-09-01

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

Evaluation of ventilators used during transport of critically ill patients: a bench study.

PubMed

Boussen, Salah; Gainnier, Marc; Michelet, Pierre

2013-11-01

To evaluate the most recent transport ventilators' operational performance regarding volume delivery in controlled mode, trigger function, and the quality of pressurization in pressure support mode. Eight recent transport ventilators were included in a bench study in order to evaluate their accuracy to deliver a set tidal volume under normal resistance and compliance conditions, ARDS conditions, and obstructive conditions. The performance of the triggering system was assessed by the measure of the decrease in pressure and the time delay required to open the inspiratory valve. The quality of pressurization was obtained by computing the integral of the pressure-time curve for the first 300 ms and 500 ms after the onset of inspiration. For the targeted tidal volumes of 300, 500, and 800 mL the errors ranged from -3% to 48%, -7% to 18%, and -5% to 25% in the normal conditions, -4% to 27%, -2% to 35%, and -3% to 35% in the ARDS conditions, and -4% to 53%, -6% to 30%, and -30% to 28% in the obstructive conditions. In pressure support mode the pressure drop range was 0.4-1.7 cm H2O, the trigger delay range was 68-198 ms, and the pressurization performance (percent of ideal pressurization, as measured by pressure-time product at 300 ms and 500 ms) ranges were -9% to 44% at 300 ms and 6%-66% at 500 ms (P < .01). There were important differences in the performance of the tested ventilators. The most recent turbine ventilators outperformed the pneumatic ventilators. The best performers among the turbine ventilators proved comparable to modern ICU ventilators.

Multifaceted bench comparative evaluation of latest intensive care unit ventilators.

PubMed

Garnier, M; Quesnel, C; Fulgencio, J-P; Degrain, M; Carteaux, G; Bonnet, F; Similowski, T; Demoule, A

2015-07-01

Independent bench studies using specific ventilation scenarios allow testing of the performance of ventilators in conditions similar to clinical settings. The aims of this study were to determine the accuracy of the latest generation ventilators to deliver chosen parameters in various typical conditions and to provide clinicians with a comprehensive report on their performance. Thirteen modern intensive care unit ventilators were evaluated on the ASL5000 test lung with and without leakage for: (i) accuracy to deliver exact tidal volume (VT) and PEEP in assist-control ventilation (ACV); (ii) performance of trigger and pressurization in pressure support ventilation (PSV); and (iii) quality of non-invasive ventilation algorithms. In ACV, only six ventilators delivered an accurate VT and nine an accurate PEEP. Eleven devices failed to compensate VT and four the PEEP in leakage conditions. Inspiratory delays differed significantly among ventilators in invasive PSV (range 75-149 ms, P=0.03) and non-invasive PSV (range 78-165 ms, P<0.001). The percentage of the ideal curve (concomitantly evaluating the pressurization speed and the levels of pressure reached) also differed significantly (range 57-86% for invasive PSV, P=0.04; and 60-90% for non-invasive PSV, P<0.001). Non-invasive ventilation algorithms efficiently prevented the decrease in pressurization capacities and PEEP levels induced by leaks in, respectively, 10 and 12 out of the 13 ventilators. We observed real heterogeneity of performance amongst the latest generation of intensive care unit ventilators. Although non-invasive ventilation algorithms appear to maintain adequate pressurization efficiently in the case of leakage, basic functions, such as delivered VT in ACV and pressurization in PSV, are often less reliable than the values displayed by the device suggest. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

Setting individualized positive end-expiratory pressure level with a positive end-expiratory pressure decrement trial after a recruitment maneuver improves oxygenation and lung mechanics during one-lung ventilation.

PubMed

Ferrando, Carlos; Mugarra, Ana; Gutierrez, Andrea; Carbonell, Jose Antonio; García, Marisa; Soro, Marina; Tusman, Gerardo; Belda, Francisco Javier

2014-03-01

We investigated whether individualized positive end-expiratory pressure (PEEP) improves oxygenation, ventilation, and lung mechanics during one-lung ventilation compared with standardized PEEP. Thirty patients undergoing thoracic surgery were randomly allocated to the study or control group. Both groups received an alveolar recruitment maneuver at the beginning and end of one-lung ventilation. After the alveolar recruitment maneuver, the control group had their lungs ventilated with a 5 cm·H2O PEEP, while the study group had their lungs ventilated with an individualized PEEP level determined by a PEEP decrement trial. Arterial blood samples, lung mechanics, and volumetric capnography were recorded at multiple timepoints throughout the procedure. The individualized PEEP values in study group were higher than the standardized PEEP values (10 ± 2 vs 5 cm·H2O; P < 0.001). In both groups, arterial oxygenation decreased when bilateral-lung ventilation was switched to one-lung ventilation and increased after the alveolar recruitment maneuver. During one-lung ventilation, oxygenation was maintained in the study group but decreased in the control group. After one-lung ventilation, arterial oxygenation was significantly higher in the study group (306 vs 231 mm·Hg, P = 0.007). Static compliance decreased in both groups when bilateral-lung ventilation was switched to one-lung ventilation. Static compliance increased significantly only in the study group (P < 0.001) after the alveolar recruitment maneuver and optimal PEEP adjustment. The alveolar recruitment maneuver did not decrease cardiac index in any patient. During one-lung ventilation, the improvements in oxygenation and lung mechanics after an alveolar recruitment maneuver were better preserved by ventilation by using individualized PEEP with a PEEP decrement trial than with a standardized 5 cm·H2O of PEEP.

21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 4 2014-04-01 2014-04-01 false Ventilation, air filtration, air heating and... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a) Adequate ventilation shall be provided. (b) Equipment for adequate control over air pressure, micro-organisms, dust...

21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 4 2013-04-01 2013-04-01 false Ventilation, air filtration, air heating and... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a) Adequate ventilation shall be provided. (b) Equipment for adequate control over air pressure, micro-organisms, dust...

21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 4 2012-04-01 2012-04-01 false Ventilation, air filtration, air heating and... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a) Adequate ventilation shall be provided. (b) Equipment for adequate control over air pressure, micro-organisms, dust...

21 CFR 211.46 - Ventilation, air filtration, air heating and cooling.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 4 2011-04-01 2011-04-01 false Ventilation, air filtration, air heating and... Buildings and Facilities § 211.46 Ventilation, air filtration, air heating and cooling. (a) Adequate ventilation shall be provided. (b) Equipment for adequate control over air pressure, micro-organisms, dust...

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.

Are there benefits or harm from pressure targeting during lung-protective ventilation?

PubMed

MacIntyre, Neil R; Sessler, Curtis N

2010-02-01

Mechanically, breath design is usually either flow/volume-targeted or pressure-targeted. Both approaches can effectively provide lung-protective ventilation, but they prioritize different ventilation parameters, so their responses to changing respiratory-system mechanics and patient effort are different. These different response behaviors have advantages and disadvantages that can be important in specific circumstances. Flow/volume targeting guarantees a set minute ventilation but sometimes may be difficult to synchronize with patient effort, and it will not limit inspiratory pressure. In contrast, pressure targeting, with its variable flow, may be easier to synchronize and will limit inspiratory pressure, but it provides no control over delivered volume. Skilled clinicians can maximize benefits and minimize problems with either flow/volume targeting or pressure targeting. Indeed, as is often the case in managing complex life-support devices, it is operator expertise rather than the device design features that most impacts patient outcomes.

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

Frequency and Intensive Care Related Risk Factors of Pneumothorax in Ventilated Neonates

PubMed Central

Bhat Yellanthoor, Ramesh; Ramdas, Vidya

2014-01-01

Objectives. Relationships of mechanical ventilation to pneumothorax in neonates and care procedures in particular are rarely studied. We aimed to evaluate the relationship of selected ventilator variables and risk events to pneumothorax. Methods. Pneumothorax was defined as accumulation of air in pleural cavity as confirmed by chest radiograph. Relationship of ventilator mode, selected settings, and risk procedures prior to detection of pneumothorax was studied using matched controls. Results. Of 540 neonates receiving mechanical ventilation, 10 (1.85%) were found to have pneumothorax. Respiratory distress syndrome, meconium aspiration syndrome, and pneumonia were the underlying lung pathology. Pneumothorax mostly (80%) occurred within 48 hours of life. Among ventilated neonates, significantly higher percentage with pneumothorax received mandatory ventilation than controls (70% versus 20%; P < 0.01). Peak inspiratory pressure >20 cm H2O and overventilation were not significantly associated with pneumothorax. More cases than controls underwent care procedures in the preceding 3 hours of pneumothorax event. Mean airway pressure change (P = 0.052) and endotracheal suctioning (P = 0.05) were not significantly associated with pneumothorax. Reintubation (P = 0.003), and bagging (P = 0.015) were significantly associated with pneumothorax. Conclusion. Pneumothorax among ventilated neonates occurred at low frequency. Mandatory ventilation and selected care procedures in the preceding 3 hours had significant association. PMID:24876958

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.

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.

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.

Tracheostomy and mechanical ventilation weaning in children affected by respiratory virus according to a weaning protocol in a pediatric intensive care unit in Argentina: an observational restrospective trial

PubMed Central

2011-01-01

We describe difficult weaning after prolonged mechanical ventilation in three tracheostomized children affected by respiratory virus infection. Although the spontaneous breathing trials were successful, the patients failed all extubations. Therefore a tracheostomy was performed and the weaning plan was begun. The strategy for weaning was the decrease of ventilation support combining pressure control ventilation (PCV) with increasing periods of continuous positive airway pressure + pressure support ventilation (CPAP + PSV) and then CPAP + PSV with increasing intervals of T-piece. They presented acute respiratory distress syndrome on admission with high requirements of mechanical ventilation (MV). Intervening factors in the capabilities and loads of the respiratory system were considered and optimized. The average MV time was 69 days and weaning time 31 days. We report satisfactory results within the context of a directed weaning protocol. PMID:21244710

Head elevation and lateral head rotation effect on facemask ventilation efficiency: Randomized crossover trials.

PubMed

Matsunami, Sayuri; Komasawa, Nobuyasu; Konishi, Yuki; Minami, Toshiaki

2017-11-01

We performed two prospective randomized crossover trials to evaluate the effect of head elevation or lateral head rotation to facemask ventilation volume. In the first trial, facemask ventilation was performed with a 12-cm high pillow (HP) and 4-cm low pillow (LP) in 20 female patients who were scheduled to undergo general anesthesia. In the second trial, facemask ventilation was performed with and without lateral head rotation in another 20 female patients. Ventilation volume was measured in a pressure-controlled ventilation (PCV) manner at 10, 15, and 20 cmH 2 O inspiratory pressures. In the first trial evaluating head elevation effect, facemask ventilation volume was significantly higher with a HP than with a LP at 15 and 20 cmH 2 O inspiratory pressure (15 cmH 2 O: HP median 540 [ IQR 480-605] mL, LP 460 [400-520] mL, P=0.006, 20 cmH 2 O: HP 705 [650-800] mL, LP 560 [520-677] mL, P<0.001). In the second trial, lateral head rotation did not significantly increase facemask ventilation volume at all inspiratory pressure. Head elevation increased facemask ventilation volume in normal airway patients, while lateral head rotation did not. Copyright © 2017 Elsevier Inc. All rights reserved.

Design and calibration of a high-frequency oscillatory ventilator.

PubMed

Simon, B A; Mitzner, W

1991-02-01

High-frequency ventilation (HFV) is a modality of mechanical ventilation which presents difficult technical demands to the clinical or laboratory investigator. The essential features of an ideal HFV system are described, including wide frequency range, control of tidal volume and mean airway pressure, minimal dead space, and high effective internal impedance. The design and performance of a high-frequency oscillatory ventilation system is described which approaches these requirements. The ventilator utilizes a linear motor regulated by a closed loop controller and driving a novel frictionless double-diaphragm piston pump. Finally, the ventilator performance is tested using the impedance model of Venegas [1].

Automated Control of Endotracheal Tube Cuff Pressure During Simulated Flight

DTIC Science & Technology

2016-06-01

ventilator, while the other two devices are stand-alone products. The fourth group of ETTs had the cuff pressure measured by the respiratory ...Maquet, Rastatt, Germany). To simulate a clinical environment, each model was ventilated using ventilator settings of respiratory rate of 12...rapidly changes with descent to below 10 cmH2O, allowing fluid above the cuff to readily move into the lower respiratory tract. As with ascent

[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.

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.

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.

Development and application of a double-piston configured, total-liquid ventilatory support device.

PubMed

Meinhardt, J P; Quintel, M; Hirschl, R B

2000-05-01

Perfluorocarbon liquid ventilation has been shown to enhance pulmonary mechanics and gas exchange in the setting of respiratory failure. To optimize the total liquid ventilation process, we developed a volume-limited, time-cycled liquid ventilatory support, consisting of an electrically actuated, microprocessor-controlled, double-cylinder, piston pump with two separate limbs for active inspiration and expiration. Prospective, controlled, animal laboratory study, involving sequential application of conventional gas ventilation, partial ventilation (PLV), and total liquid ventilation (TLV). Research facility at a university medical center. A total of 12 normal adult New Zealand rabbits weighing 3.25+/-0.1 kg. Anesthestized rabbits were supported with gas ventilation for 30 mins (respiratory rate, 20 cycles/min; peak inspiratory pressure, 15 cm H2O; end-expiratory pressure, 5 cm H2O), then PLV was established with perflubron (12 mL/kg). After 15 mins, TLV was instituted (tidal volume, 18 mL/kg; respiratory rate, 7 cycles/min; inspiratory/expiratory ratio, 1:2 cycles/min). After 4 hrs of TLV, PLV was re-established. Of 12 animals, nine survived the 4-hr TLV period. During TLV, mean values +/- SEM were as follows: PaO2, 363+/-30 torr; PaCO2, 39+/-1.5 torr; pH, 7.39+/-0.01; static peak inspiratory pressure, 13.2+/-0.2 cm H2O; static endexpiratory pressure, 5.5+/-0.1 cm H2O. No significant changes were observed. When compared with gas ventilation and PLV, significant increases occurred in mean arterial pressure (62.4+/-3.5 torr vs. 74.0+/-1.2 torr) and central venous pressure (5.6+/-0.7 cm H2O vs. 7.8+/-0.2 cm H2O) (p < .05). Total liquid ventilation can be performed successfully utilizing piston pumps with active expiration. Considering the enhanced flow profiles, this device configuration provides advantages over others.

Controlled invasive mechanical ventilation strategies in obese patients undergoing surgery.

PubMed

Maia, Lígia de Albuquerque; Silva, Pedro Leme; Pelosi, Paolo; Rocco, Patricia Rieken Macedo

2017-06-01

The obesity prevalence is increasing in surgical population. As the number of obese surgical patients increases, so does the demand for mechanical ventilation. Nevertheless, ventilatory strategies in this population are challenging, since obesity results in pathophysiological changes in respiratory function. Areas covered: We reviewed the impact of obesity on respiratory system and the effects of controlled invasive mechanical ventilation strategies in obese patients undergoing surgery. To date, there is no consensus regarding the optimal invasive mechanical ventilation strategy for obese surgical patients, and no evidence that possible intraoperative beneficial effects on oxygenation and mechanics translate into better postoperative pulmonary function or improved outcomes. Expert commentary: Before determining the ideal intraoperative ventilation strategy, it is important to analyze the pathophysiology and comorbidities of each obese patient. Protective ventilation with low tidal volume, driving pressure, energy, and mechanical power should be employed during surgery; however, further studies are required to clarify the most effective ventilation strategies, such as the optimal positive end-expiratory pressure and whether recruitment maneuvers minimize lung injury. In this context, an ongoing trial of intraoperative ventilation in obese patients (PROBESE) should help determine the mechanical ventilation strategy that best improves clinical outcome in patients with body mass index≥35kg/m 2 .

Carbon dioxide clearance in rabbits during expiratory phase intratracheal pulmonary ventilation.

PubMed

Meyappan, Raju T; Raszynski, Andre; Bohorquez, Jorge; Totapally, Balagangadhar R; Koul, Pulin B; Norozian, Faraz M; Valcourt, Karl; Torbati, Dan

2007-01-01

The purpose of this study was to compare the efficacy of CO2 removal during conventional mechanical ventilation (CMV) with and without expiratory phase intratracheal pulmonary ventilation (expiratory ITPV or Exp-ITPV); and to compare CO2 clearance during Exp-ITPV, in pressure-controlled ventilation (PCV) and in volume-controlled ventilation (VCV) modes. Seven anesthetized rabbits were tracheotomized and intubated using a 4 mm endotracheal tube. Venous and arterial lines were established. The rabbits were paralyzed, mechanically ventilated, and ventilation parameters were adjusted to achieve baseline arterial hypercapnia. Animals were then ventilated during 30-minute trials of CMV and Exp-ITPV, in both PCV and VCV modes. A custom-built, microprocessor-controlled solenoid valve was used to limit ITPV gas flow to the expiratory phase. Proximal and carinal airway pressures and hemodynamic variables were continuously recorded, and arterial blood gases were analyzed at the end of each trial. Exp-ITPV, as compared with CMV, reduced arterial PCO2 by 12% and 21% in PCV and VCV modes, respectively (p < 0.02 and p < 0.001; one-sided paired t test), without significant changes in other cardiorespiratory variables. In conclusion, Exp-ITPV is more effective than CMV in clearing CO2 through a small endotracheal tube. Exp-ITPV is also more effective in VCV mode than PCV mode.

Are tidal volume measurements in neonatal pressure-controlled ventilation accurate?

PubMed

Chow, Lily C; Vanderhal, Andre; Raber, Jorge; Sola, Augusto

2002-09-01

Bedside pulmonary mechanics monitors (PMM) have become useful in ventilatory management in neonates. These monitors are used more frequently due to recent improvements in data-processing capabilities. PMM devices are often part of the ventilator or are separate units. The accuracy and reliability of these systems have not been carefully evaluated. We compared a single ventilatory parameter, tidal volume (V(t)), as measured by several systems. We looked at two freestanding PMMs: the Ventrak Respiratory Monitoring System (Novametrix, Wallingford, CT) and the Bicore CP-100 Neonatal Pulmonary Monitor (Allied Health Care Products, Riverside, CA), and three ventilators with built-in PMM: the VIP Bird Ventilator (Bird Products Corp., Palm Springs, CA), Siemens Servo 300A (Siemens-Elema AB, Solna, Sweden), and Drager Babylog 8000 (Drager, Inc., Chantilly, VA). A calibrated syringe (Hans Rudolph, Inc., Kansas City, MO) was used to deliver tidal volumes of 4, 10, and 20 mL to each ventilator system coupled with a freestanding PMM. After achieving steady state, six consecutive V(t) readings were taken simultaneously from the freestanding PMM and each ventilator. In a second portion of the bench study, we used pressure-control ventilation and measured exhaled tidal volume (V(te)) while ventilating a Bear Test Lung with the same three ventilators. We adjusted peak inspiratory pressure (PIP) under controlled conditions to achieve the three different targeted tidal volumes on the paired freestanding PMM. Again, six V(te) measurements were recorded for each tidal volume. Means and standard deviations were calculated.The percentage difference in measurement of V(t) delivered by calibrated syringe varied greatly, with the greatest discrepancy seen in the smallest tidal volumes, by up to 28%. In pressure control mode, V(te) as measured by the Siemens was significantly overestimated by 20-95%, with the biggest discrepancy at the smallest V(te), particularly when paired with the Bicore PMM. V(te), as measured by the VIP Bird and Drager paired with the Ventrak PMM, had a tendency to underestimate V(t) by up to 25% at the smallest V(te). However, when paired with the Bicore PMM, these same two ventilators read over target by up to 18%. Under controlled laboratory conditions, we demonstrated that true delivered V(te), as measured by the three ventilators and two freestanding PMM, differed markedly. In general, decreasing dynamic compliance of the tubing was not associated with greater inaccuracy in V(te) measurements. Copyright 2002 Wiley-Liss, Inc.

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.

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.

Technology for noninvasive mechanical ventilation: looking into the black box

PubMed Central

Navajas, Daniel; Montserrat, Josep M.

2016-01-01

Current devices for providing noninvasive respiratory support contain sensors and built-in intelligence for automatically modifying ventilation according to the patient's needs. These devices, including automatic continuous positive airway pressure devices and noninvasive ventilators, are technologically complex and offer a considerable number of different modes of ventilation and setting options, the details of which are sometimes difficult to capture by the user. Therefore, better predicting and interpreting the actual performance of these ventilation devices in clinical application requires understanding their functioning principles and assessing their performance under well controlled bench test conditions with simulated patients. This concise review presents an updated perspective of the theoretical basis of intelligent continuous positive airway pressure and noninvasive ventilation devices, and of the tools available for assessing how these devices respond under specific ventilation phenotypes in patients requiring breathing support. PMID:27730162

Automated respiratory cycles selection is highly specific and improves respiratory mechanics analysis.

PubMed

Rigo, Vincent; Graas, Estelle; Rigo, Jacques

2012-07-01

Selected optimal respiratory cycles should allow calculation of respiratory mechanic parameters focusing on patient-ventilator interaction. New computer software automatically selecting optimal breaths and respiratory mechanics derived from those cycles are evaluated. Retrospective study. University level III neonatal intensive care unit. Ten mins synchronized intermittent mandatory ventilation and assist/control ventilation recordings from ten newborns. The ventilator provided respiratory mechanic data (ventilator respiratory cycles) every 10 secs. Pressure, flow, and volume waves and pressure-volume, pressure-flow, and volume-flow loops were reconstructed from continuous pressure-volume recordings. Visual assessment determined assisted leak-free optimal respiratory cycles (selected respiratory cycles). New software graded the quality of cycles (automated respiratory cycles). Respiratory mechanic values were derived from both sets of optimal cycles. We evaluated quality selection and compared mean values and their variability according to ventilatory mode and respiratory mechanic provenance. To assess discriminating power, all 45 "t" values obtained from interpatient comparisons were compared for each respiratory mechanic parameter. A total of 11,724 breaths are evaluated. Automated respiratory cycle/selected respiratory cycle selections agreement is high: 88% of maximal κ with linear weighting. Specificity and positive predictive values are 0.98 and 0.96, respectively. Averaged values are similar between automated respiratory cycle and ventilator respiratory cycle. C20/C alone is markedly decreased in automated respiratory cycle (1.27 ± 0.37 vs. 1.81 ± 0.67). Tidal volume apparent similarity disappears in assist/control: automated respiratory cycle tidal volume (4.8 ± 1.0 mL/kg) is significantly lower than for ventilator respiratory cycle (5.6 ± 1.8 mL/kg). Coefficients of variation decrease for all automated respiratory cycle parameters in all infants. "t" values from ventilator respiratory cycle data are two to three times higher than ventilator respiratory cycles. Automated selection is highly specific. Automated respiratory cycle reflects most the interaction of both ventilator and patient. Improving discriminating power of ventilator monitoring will likely help in assessing disease status and following trends. Averaged parameters derived from automated respiratory cycles are more precise and could be displayed by ventilators to improve real-time fine tuning of ventilator settings.

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.

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.

Effects of assisted and variable mechanical ventilation on cardiorespiratory interactions in anesthetized pigs.

PubMed

Beda, Alessandro; Güldner, Andreas; Simpson, David M; Carvalho, Nadja C; Franke, Susanne; Uhlig, Christopher; Koch, Thea; Pelosi, Paolo; de Abreu, Marcelo Gama

2012-03-01

The physiological importance of respiratory sinus arrhythmia (RSA) and cardioventilatory coupling (CVC) has not yet been fully elucidated, but these phenomena might contribute to improve ventilation/perfusion matching, with beneficial effects on gas exchange. Furthermore, decreased RSA amplitude has been suggested as an indicator of impaired autonomic control and poor clinical outcome, also during positive-pressure mechanical ventilation (MV). However, it is currently unknown how different modes of MV, including variable tidal volumes (V(T)), affect RSA and CVC during anesthesia. We compared the effects of pressure controlled (PCV) versus pressure assisted (PSV) ventilation, and of random variable versus constant V(T), on RSA and CVC in eight anesthetized pigs. At comparable depth of anesthesia, global hemodynamics, and ventilation, RSA amplitude increased from 20 ms in PCV to 50 ms in PSV (p < 0.05). CVC was detected (using proportional Shannon entropy of the interval between each inspiration onset and the previous R-peak in ECG) in two animals in PCV and seven animals in PSV. Variable V(T) did not significantly influence these phenomena. Furthermore, heart period and systolic arterial pressure oscillations were in phase during PCV but in counter-phase during PSV. At the same depth of anesthesia in pigs, PSV increases RSA amplitude and CVC compared to PCV. Our data suggest that the central respiratory drive, but not the baroreflex or the mechano-electric feedback in the heart, is the main mechanism behind the RSA increase. Hence, differences in RSA and CVC between mechanically ventilated patients might reflect the difference in ventilation mode rather than autonomic impairment. Also, since gas exchange did not increase from PCV to PSV, it is questionable whether RSA has any significance in improving ventilation/perfusion matching during MV.

Causes Of Low Efficiency Of Combined Ventilation System In Coal Mines In Resolving The Problem Of Air Leaks (Inflows) Between Levels And Surface

NASA Astrophysics Data System (ADS)

Popov, Valeriy; Filatov, Yuriy; Lee, Hee; Golik, Anatoliy

2017-11-01

The paper discusses the problem of the underground mining safety control. The long-term air intake to coal accumulations is reviewed as one of the reasons of endogenous fires during mining. The methods of combating air leaks (inflows) in order to prevent endogenous fires are analyzed. The calculations showing the discrepancy between the design calculations for the mine ventilation, disregarding a number of mining-andgeological and mining-engineering factors, and the actual conditions of mining are given. It is proved that the conversion of operating mines to combined (pressure and exhaust) ventilation system in order to reduce the endogenous fire hazard of underground mining is unreasonable due to impossibility of providing an optimal distribution of aerodynamic pressure in mines. The conversion does not exclude the entry of air into potentially hazardous zones of endogenous fires. The essence of the combined application of positive and negative control methods for the distribution of air pressure is revealed. It consists of air doors installation in easily ventilated airways and installation of pressure equalization chambers equipped with auxiliary fans near the stoppings, working sections and in parallel airways.The effectiveness of the combined application of negative and positive control methods for the air pressure distribution in order to reduce endogenous fire hazard of mining operations is proved.

Continuous versus intermittent endotracheal cuff pressure control for the prevention of ventilator-associated respiratory infections in Vietnam: study protocol for a randomised controlled trial.

PubMed

Dat, Vu Quoc; Geskus, Ronald B; Wolbers, Marcel; Loan, Huynh Thi; Yen, Lam Minh; Binh, Nguyen Thien; Chien, Le Thanh; Mai, Nguyen Thi Hoang; Phu, Nguyen Hoan; Lan, Nguyen Phu Huong; Hao, Nguyen Van; Long, Hoang Bao; Thuy, Tran Phuong; Kinh, Nguyen Van; Trung, Nguyen Vu; Phu, Vu Dinh; Cap, Nguyen Trung; Trinh, Dao Tuyet; Campbell, James; Kestelyn, Evelyne; Wertheim, Heiman F L; Wyncoll, Duncan; Thwaites, Guy Edward; van Doorn, H Rogier; Thwaites, C Louise; Nadjm, Behzad

2018-04-04

Ventilator-associated respiratory infection (VARI) comprises ventilator-associated pneumonia (VAP) and ventilator-associated tracheobronchitis (VAT). Although their diagnostic criteria vary, together these are the most common hospital-acquired infections in intensive care units (ICUs) worldwide, responsible for a large proportion of antibiotic use within ICUs. Evidence-based strategies for the prevention of VARI in resource-limited settings are lacking. Preventing the leakage of oropharyngeal secretions into the lung using continuous endotracheal cuff pressure control is a promising strategy. The aim of this study is to investigate the efficacy of automated, continuous endotracheal cuff pressure control in preventing the development of VARI and reducing antibiotic use in ICUs in Vietnam. This is an open-label randomised controlled multicentre trial. We will enrol 600 adult patients intubated for ≤ 24 h at the time of enrolment. Eligible patients will be stratified according to admission diagnosis (180 tetanus, 420 non-tetanus) and site and will be randomised in a 1:1 ratio to receive either (1) automated, continuous control of endotracheal cuff pressure or (2) intermittent measurement and control of endotracheal cuff pressure using a manual cuff pressure meter. The primary outcome is the occurrence of VARI, defined as either VAP or VAT during the ICU admission up to a maximum of 90 days after randomisation. Patients in both groups who are at risk for VARI will receive a standardised battery of investigations if their treating physician feels a new infection has occurred, the results of which will be used by an endpoint review committee, blinded to the allocated arm and independent of patient care, to determine the primary outcome. All enrolled patients will be followed for mortality and endotracheal tube cuff-related complications at 28 days and 90 days after randomisation. Other secondary outcomes include antibiotic use; days ventilated, in ICU and in hospital; inpatient mortality; costs of antibiotics in ICU; duration of ICU stay; and duration of hospital stay. This study will provide high-quality evidence concerning the use of continuous endotracheal cuff pressure control as a method to reduce VARI, antibiotic use and hospitalisation costs and to shorten stay. ClinicalTrials.gov, NCT02966392 . Registered on November 9, 2016. Protocol version: 2.0; issue date March 3, 2017.

Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations

NASA Technical Reports Server (NTRS)

Koh, J.; Brown, T. E.; Beightol, L. A.; Eckberg, D. L.

1998-01-01

We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P < 0.05). Respiratory frequency R-R interval spectral power (used as an index of respiratory sinus arrhythmia) declined dramatically with sedation and muscle paralysis (P < 0.05), but was greater during conventional mechanical, than high frequency jet ventilation (P < 0.05). These results suggest that although phasic inputs from pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

Randomized prospective crossover study of biphasic intermittent positive airway pressure ventilation (BIPAP) versus pressure support ventilation (PSV) in surgical intensive care patients.

PubMed

Elrazek, E Abd

2004-10-01

The aim of this prospective, randomized and crossover study was to assess the role of a relatively new mode of mechanical ventilation, biphasic intermittent positive airway pressure (BIPAP) in comparison to another well established one, pressure-support ventilation (PSV) in surgical intensive care patients. 24 generally stable patients, breathing on their own after short-term (< 24 hours) postoperative controlled mechanical ventilation (CMV) were randomized to start on either PSV or BIPAP, and indirect calorimetry measurements were performed after 1 hour adaptation period at two time intervals; immediately after the investigated ventilatory mode was started and 1 hour later. Statistics included a two-tailed paired t-test to compare the two sets of different data, p < 0.5 was considered significant. Oxygen consumption (VO2), energy expenditure (EE), Carbon dioxide production (VCO2), and respiratory quotient (RQ) did not differ significantly between the two groups. There were also no significant differences regarding respiratory rate (RR), minute volume (MV) and arterial blood gas analysis (ABGs). Both modes of ventilation were well tolerated by all patients. PSV and BIPAP can be used for weaning patients comfortably in surgical intensive care after short-term postoperative ventilation. BIPAP may have the credit of being smoother than PSV where no patient effort is required.

46 CFR 154.707 - Cargo boil-off as fuel: Ventilation.

Code of Federal Regulations, 2011 CFR

2011-10-01

... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.707 Cargo boil-off as fuel: Ventilation. (a) A...

46 CFR 154.707 - Cargo boil-off as fuel: Ventilation.

Code of Federal Regulations, 2012 CFR

2012-10-01

... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.707 Cargo boil-off as fuel: Ventilation. (a) A...

46 CFR 154.707 - Cargo boil-off as fuel: Ventilation.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.707 Cargo boil-off as fuel: Ventilation. (a) A...

46 CFR 154.707 - Cargo boil-off as fuel: Ventilation.

Code of Federal Regulations, 2013 CFR

2013-10-01

... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.707 Cargo boil-off as fuel: Ventilation. (a) A...

46 CFR 154.707 - Cargo boil-off as fuel: Ventilation.

Code of Federal Regulations, 2014 CFR

2014-10-01

... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Design, Construction and Equipment Cargo Pressure and Temperature Control § 154.707 Cargo boil-off as fuel: Ventilation. (a) A...

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.

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.

Gravity predominates over ventilatory pattern in the prevention of ventilator-associated pneumonia.

PubMed

Li Bassi, Gianluigi; Marti, Joan Daniel; Saucedo, Lina; Rigol, Montserrat; Roca, Ignasi; Cabanas, Maria; Muñoz, Laura; Ranzani, Otavio Tavares; Giunta, Valeria; Luque, Nestor; Esperatti, Mariano; Gabarrus, Albert; Fernandez, Laia; Rinaudo, Mariano; Ferrer, Miguel; Ramirez, Jose; Vila, Jordi; Torres, Antoni

2014-09-01

In the semirecumbent position, gravity-dependent dissemination of pathogens has been implicated in the pathogenesis of ventilator-associated pneumonia. We compared the preventive effects of a ventilatory strategy, aimed at decreasing pulmonary aspiration and enhancing mucus clearance versus the Trendelenburg position. Prospective randomized animal study. Animal research facility, University of Barcelona, Spain. Twenty-four Large White-Landrace pigs. Pigs were intubated and on mechanical ventilation for 72 hours. Following surgical preparation, pigs were randomized to be positioned: 1) in semirecumbent/prone position, ventilated with a duty cycle (TITTOT) of 0.33 and without positive end-expiratory pressure (control); 2) as in the control group, positive end-expiratory pressure of 5 cm H2O and TITTOT to achieve a mean expiratory-inspiratory flow bias of 10 L/min (treatment); 3) in Trendelenburg/prone position and ventilated as in the control group (Trendelenburg). Following randomization, Pseudomonas aeruginosa was instilled into the oropharynx. Mucus clearance rate was measured through fluoroscopic tracking of tracheal markers. Microspheres were instilled into the subglottic trachea to assess pulmonary aspiration. Ventilator-associated pneumonia was confirmed by histological/microbiological studies. The mean expiratory-inspiratory flow in the treatment, control, and Trendelenburg groups were 10.7 ± 1.7, 1.8 ± 3.7 and 4.3 ± 2.8 L/min, respectively (p < 0.001). Mucus clearance rate was 11.3 ± 9.9 mm/min in the Trendelenburg group versus 0.1 ± 1.0 in the control and 0.2 ± 1.0 in the treatment groups (p = 0.002). In the control group, we recovered 1.35% ± 1.24% of the instilled microspheres per gram of tracheal secretions, whereas 0.22% ± 0.25% and 0.97% ± 1.44% were recovered in the treatment and Trendelenburg groups, respectively (p = 0.031). Ventilator-associated pneumonia developed in 66.67%, 85.71%, and 0% of the animals in the control, treatment, and Trendelenburg groups (p < 0.001). The Trendelenburg position predominates over expiratory flow bias and positive end-expiratory pressure in the prevention of gravity-dependent translocation of oropharyngeal pathogens and development of ventilator-associated pneumonia. These findings further substantiate the primary role of gravity in the pathogenesis of ventilator-associated pneumonia.

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.

Influence of bronchial diameter change on the airflow dynamics based on a pressure-controlled ventilation system.

PubMed

Ren, Shuai; Cai, Maolin; Shi, Yan; Xu, Weiqing; Zhang, Xiaohua Douglas

2018-03-01

Bronchial diameter is a key parameter that affects the respiratory treatment of mechanically ventilated patients. In this paper, to reveal the influence of bronchial diameter on the airflow dynamics of pressure-controlled mechanically ventilated patients, a new respiratory system model is presented that combines multigeneration airways with lungs. Furthermore, experiments and simulation studies to verify the model are performed. Finally, through the simulation study, it can be determined that in airway generations 2 to 7, when the diameter is reduced to half of the original value, the maximum air pressure (maximum air pressure in lungs) decreases by nearly 16%, the maximum flow decreases by nearly 30%, and the total airway pressure loss (sum of each generation pressure drop) is more than 5 times the original value. Moreover, in airway generations 8 to 16, with increasing diameter, the maximum air pressure, maximum flow, and total airway pressure loss remain almost constant. When the diameter is reduced to half of the original value, the maximum air pressure decreases by 3%, the maximum flow decreases by nearly 5%, and the total airway pressure loss increases by 200%. The study creates a foundation for improvement in respiratory disease diagnosis and treatment. Copyright © 2017 John Wiley & Sons, Ltd.

Proportional assist ventilation system based on proportional solenoid valve control.

PubMed

Lua, A C; Shi, K C; Chua, L P

2001-07-01

A new proportional assist ventilation (PAV) method using a proportional solenoid valve (PSV) to control air supply to patients suffering from respiratory disabilities, was studied. The outlet flow and pressure from the proportional solenoid valve at various air supply pressures were tested and proven to be suitable for pressure and flow control in a PAV system. In vitro tests using a breathing simulator, which has been proven to possess the general characteristics of human respiratory system in spontaneous breathing tests, were conducted and the results demonstrated the viability of this PAV system in normalizing the breathing patterns of patients with abnormally high resistances and elastances as well as neuromuscular weaknesses. With a back-up safety mechanism incorporated in the control program, pressure "run-away" can be effectively prevented and safe operation of the system can be guaranteed.

Noninvasive Ventilation During Immediate Postoperative Period in Cardiac Surgery Patients: Systematic Review and Meta-Analysis

PubMed Central

Pieczkoski, Suzimara Monteiro; Margarites, Ane Glauce Freitas; Sbruzzi, Graciele

2017-01-01

Objective To verify the effectiveness of noninvasive ventilation compared to conventional physiotherapy or oxygen therapy in the mortality rate and prevention of pulmonary complications in patients during the immediate postoperative period of cardiac surgery. Methods Systematic review and meta-analysis recorded in the International Prospective Register of Ongoing Systematic Reviews (number CRD42016036441). The research included the following databases: MEDLINE, Cochrane Central, PEDro, LILACS and manual search of the references of studies published until March 2016. The review included randomized controlled trials with patients during the immediate postoperative period of cardiac surgery, which compared the use of noninvasive ventilation, BiLevel modes, continuous positive airway pressure, intermittent positive pressure breathing and positive pressure ventilation with conventional physiotherapy or oxygen therapy, and assessed the mortality rate, occurrence of pulmonary complications (atelectasis, pneumonia, acute respiratory failure, hypoxemia), reintubation rate, ventilation time, time spent in the intensive care unit (ICU), length of hospital stay and partial pressure of oxygen. Results Among the 479 selected articles, ten were included in the systematic review (n=1050 patients) and six in the meta-analysis. The use of noninvasive ventilation did not significantly reduce the risk for atelectasis (RR: 0.60; CI95% 0.28-1.28); pneumonia (RR: 0.20; CI95% 0.04-1.16), reintubation rate (RR: 0.51; CI95%: 0.15-1.66), and time spent in the ICU (-0.04 days; CI95%: -0.13; 0.05). Conclusion Prophylactic noninvasive ventilation did not significantly reduce the occurrence of pulmonary complications such as atelectasis, pneumonia, reintubation rate and time spent in the ICU. The use is still unproven and new randomized controlled trials should be carried out. PMID:28977203

Respiratory muscle activity and patient–ventilator asynchrony during different settings of noninvasive ventilation in stable hypercapnic COPD: does high inspiratory pressure lead to respiratory muscle unloading?

PubMed Central

Duiverman, Marieke L; Huberts, Anouk S; van Eykern, Leo A; Bladder, Gerrie; Wijkstra, Peter J

2017-01-01

Introduction High-intensity noninvasive ventilation (NIV) has been shown to improve outcomes in stable chronic obstructive pulmonary disease patients. However, there is insufficient knowledge about whether with this more controlled ventilatory mode optimal respiratory muscle unloading is provided without an increase in patient–ventilator asynchrony (PVA). Patients and methods Ten chronic obstructive pulmonary disease patients on home mechanical ventilation were included. Four different ventilatory settings were investigated in each patient in random order, each for 15 min, varying the inspiratory positive airway pressure and backup breathing frequency. With surface electromyography (EMG), activities of the intercostal muscles, diaphragm, and scalene muscles were determined. Furthermore, pressure tracings were derived simultaneously in order to assess PVA. Results Compared to spontaneous breathing, the most pronounced decrease in EMG activity was achieved with the high-pressure settings. Adding a high breathing frequency did reduce EMG activity per breath, while the decrease in EMG activity over 1 min was comparable with the high-pressure, low-frequency setting. With high backup breathing frequencies less breaths were pressure supported (25% vs 97%). PVAs occurred more frequently with the low-frequency settings (P=0.017). Conclusion High-intensity NIV might provide optimal unloading of respiratory muscles, without undue increases in PVA. PMID:28138234

Respiratory muscle activity and patient-ventilator asynchrony during different settings of noninvasive ventilation in stable hypercapnic COPD: does high inspiratory pressure lead to respiratory muscle unloading?

PubMed

Duiverman, Marieke L; Huberts, Anouk S; van Eykern, Leo A; Bladder, Gerrie; Wijkstra, Peter J

2017-01-01

High-intensity noninvasive ventilation (NIV) has been shown to improve outcomes in stable chronic obstructive pulmonary disease patients. However, there is insufficient knowledge about whether with this more controlled ventilatory mode optimal respiratory muscle unloading is provided without an increase in patient-ventilator asynchrony (PVA). Ten chronic obstructive pulmonary disease patients on home mechanical ventilation were included. Four different ventilatory settings were investigated in each patient in random order, each for 15 min, varying the inspiratory positive airway pressure and backup breathing frequency. With surface electromyography (EMG), activities of the intercostal muscles, diaphragm, and scalene muscles were determined. Furthermore, pressure tracings were derived simultaneously in order to assess PVA. Compared to spontaneous breathing, the most pronounced decrease in EMG activity was achieved with the high-pressure settings. Adding a high breathing frequency did reduce EMG activity per breath, while the decrease in EMG activity over 1 min was comparable with the high-pressure, low-frequency setting. With high backup breathing frequencies less breaths were pressure supported (25% vs 97%). PVAs occurred more frequently with the low-frequency settings ( P =0.017). High-intensity NIV might provide optimal unloading of respiratory muscles, without undue increases in PVA.

Case study of controlled recirculation at a Wyoming trona mine

PubMed Central

Pritchard, C.; Scott, D.; Frey, G.

2015-01-01

Controlled recirculation has been used in the metal/nonmetal mining industry for energy savings when heating and cooling air, in undersea mining and for increasing airflow to mining areas. For safe and effective use of controlled district recirculation, adequate airflow to dilute contaminants must exist prior to implementation, ventilation circuit parameters must be accurately quantified, ventilation network modeling must be up to date, emergency planning scenarios must be performed and effective monitoring and control systems must be installed and used. Safety and health issues that must be considered and may be improved through the use of controlled district recirculation include blasting fumes, dust, diesel emissions, radon and contaminants from mine fires. Controlled recirculation methods are expected to become more widely used as mines reach greater working depths, requiring that these health and safety issues be well understood. The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted two controlled recirculation tests over three days at a Wyoming trona mine, utilizing an inline booster fan to improve airflow to a remote and difficult-to-ventilate development section. Test results were used to determine the effect that recirculation had on air qualities and quantities measured in that section and in other adjacent areas. Pre-test conditions, including ventilation quantities and pressures, were modeled using VnetPC. During each test, ventilation quantities and pressures were measured, as well as levels of total dust. Sulfur hexafluoride (SF6) tracer gas was used to simulate a mine contaminant to monitor recirculation wave cycles. Results showed good correlation between the model results and measured values for airflows, pressure differentials, tracer gas arrival times, mine gasses and dust levels. PMID:26251567

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.

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.

Crew Survivability After a Rapid Cabin Depressurization Event

NASA Technical Reports Server (NTRS)

Sargusingh, Miriam J.

2012-01-01

Anecdotal evidence acquired through historic failure investigations involving rapid cabin decompression (e.g. Challenger, Columbia and Soyuz 11) show that full evacuation of the cabin atmosphere may occur within seconds. During such an event, the delta-pressure between the sealed suit ventilation system and the cabin will rise at the rate of the cabin depressurization; potentially at a rate exceeding the capability of the suit relief valve. It is possible that permanent damage to the suit pressure enclosure and ventilation loop components may occur as the integrated system may be subjected to delta pressures in excess of the design-to pressures. Additionally, as the total pressure of the suit ventilation system decreases, so does the oxygen available to the crew. The crew may be subjected to a temporarily incapacitating, but non-lethal, hypoxic environment. It is expected that the suit will maintain a survivable atmosphere on the crew until the vehicle pressure control system recovers or the cabin has otherwise attained a habitable environment. A common finding from the aforementioned reports indicates that the crew would have had a better chance at surviving the event had they been in a protective configuration, that is, in a survival suit. Making use of these lessons learned, the Constellation Program implemented a suit loop in the spacecraft design and required that the crew be in a protective configuration, that is suited with gloves on and visors down, during dynamic phases of flight that pose the greatest risk for a rapid and uncontrolled cabin depressurization event: ascent, entry, and docking. This paper details the evaluation performed to derive suit pressure garment and ventilation system performance parameters that would lead to the highest probability of crew survivability after an uncontrolled crew cabin depressurization event while remaining in the realm of practicality for suit design. This evaluation involved: (1) assessment of stakeholder expectations to validate the functionality being imposed; (2) review/refinement of concept of operations to establish the potential triggers for such an event and define the response of the spacecraft and suit ventilation loop pressure control systems; and (3) assessment of system capabilities with respect to structural capability and pressure control.

Negative pressure ventilation and positive pressure ventilation promote comparable levels of ventilator-induced diaphragmatic dysfunction in rats.

PubMed

Bruells, Christian S; Smuder, Ashley J; Reiss, Lucy K; Hudson, Matthew B; Nelson, William Bradley; Wiggs, Michael P; Sollanek, Kurt J; Rossaint, Rolf; Uhlig, Stefan; Powers, Scott K

2013-09-01

Mechanical ventilation is a life-saving intervention for patients with respiratory failure. Unfortunately, a major complication associated with prolonged mechanical ventilation is ventilator-induced diaphragmatic atrophy and contractile dysfunction, termed ventilator-induced diaphragmatic dysfunction (VIDD). Emerging evidence suggests that positive pressure ventilation (PPV) promotes lung damage (ventilator-induced lung injury [VILI]), resulting in the release of signaling molecules that foster atrophic signaling in the diaphragm and the resultant VIDD. Although a recent report suggests that negative pressure ventilation (NPV) results in less VILI than PPV, it is unknown whether NPV can protect against VIDD. Therefore, the authors tested the hypothesis that compared with PPV, NPV will result in a lower level of VIDD. Adult rats were randomly assigned to one of three experimental groups (n = 8 each): (1) acutely anesthetized control (CON), (2) 12 h of PPV, and (3) 12 h of NPV. Dependent measures included indices of VILI, diaphragmatic muscle fiber cross-sectional area, diaphragm contractile properties, and the activity of key proteases in the diaphragm. Our results reveal that no differences existed in the degree of VILI between PPV and NPV animals as evidenced by VILI histological scores (CON = 0.082 ± 0.001; PPV = 0.22 ± 0.04; NPV = 0.25 ± 0.02; mean ± SEM). Both PPV and NPV resulted in VIDD. Importantly, no differences existed between PPV and NPV animals in diaphragmatic fiber cross-sectional area, contractile properties, and the activation of proteases. These results demonstrate that NPV and PPV result in similar levels of VILI and that NPV and PPV promote comparable levels of VIDD in rats.

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.

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

New modes of assisted mechanical ventilation.

PubMed

Suarez-Sipmann, F

2014-05-01

Recent major advances in mechanical ventilation have resulted in new exciting modes of assisted ventilation. Compared to traditional ventilation modes such as assisted-controlled ventilation or pressure support ventilation, these new modes offer a number of physiological advantages derived from the improved patient control over the ventilator. By implementing advanced closed-loop control systems and using information on lung mechanics, respiratory muscle function and respiratory drive, these modes are specifically designed to improve patient-ventilator synchrony and reduce the work of breathing. Depending on their specific operational characteristics, these modes can assist spontaneous breathing efforts synchronically in time and magnitude, adapt to changing patient demands, implement automated weaning protocols, and introduce a more physiological variability in the breathing pattern. Clinicians have now the possibility to individualize and optimize ventilatory assistance during the complex transition from fully controlled to spontaneous assisted ventilation. The growing evidence of the physiological and clinical benefits of these new modes is favoring their progressive introduction into clinical practice. Future clinical trials should improve our understanding of these modes and help determine whether the claimed benefits result in better outcomes. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

Efficacy of respiratory muscle training in weaning of mechanical ventilation in patients with mechanical ventilation for 48hours or more: A Randomized Controlled Clinical Trial.

PubMed

Sandoval Moreno, L M; Casas Quiroga, I C; Wilches Luna, E C; García, A F

2018-02-02

To evaluate the efficacy of respiratory muscular training in the weaning of mechanical ventilation and respiratory muscle strength in patients on mechanical ventilation of 48hours or more. Randomized controlled trial of parallel groups, double-blind. Ambit: Intensive Care Unit of a IV level clinic in the city of Cali. 126 patients in mechanical ventilation for 48hours or more. The experimental group received daily a respiratory muscle training program with treshold, adjusted to 50% of maximal inspiratory pressure, additional to standard care, conventional received standard care of respiratory physiotherapy. MAIN INTEREST VARIABLES: weaning of mechanical ventilation. Other variables evaluated: respiratory muscle strength, requirement of non-invasive mechanical ventilation and frequency of reintubation. intention-to-treat analysis was performed with all variables evaluated and analysis stratified by sepsis condition. There were no statistically significant differences in the median weaning time of the MV between the groups or in the probability of extubation between groups (HR: 0.82 95% CI: 0.55-1.20 P=.29). The maximum inspiratory pressure was increased in the experimental group on average 9.43 (17.48) cmsH20 and in the conventional 5.92 (11.90) cmsH20 (P=.48). The difference between the means of change in maximal inspiratory pressure was 0.46 (P=.83 95%CI -3.85 to -4.78). respiratory muscle training did not demonstrate efficacy in the reduction of the weaning period of mechanical ventilation nor in the increase of respiratory muscle strength in the study population. Registered study at ClinicalTrials.gov (NCT02469064). Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

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.

Implementation of a Goal-Directed Mechanical Ventilation Order Set Driven by Respiratory Therapists Improves Compliance With Best Practices for Mechanical Ventilation.

PubMed

Radosevich, Misty A; Wanta, Brendan T; Meyer, Todd J; Weber, Verlin W; Brown, Daniel R; Smischney, Nathan J; Diedrich, Daniel A

2017-01-01

Data regarding best practices for ventilator management strategies that improve outcomes in acute respiratory distress syndrome (ARDS) are readily available. However, little is known regarding processes to ensure compliance with these strategies. We developed a goal-directed mechanical ventilation order set that included physician-specified lung-protective ventilation and oxygenation goals to be implemented by respiratory therapists (RTs). We sought as a primary outcome to determine whether an RT-driven order set with predefined oxygenation and ventilation goals could be implemented and associated with improved adherence with best practice. We evaluated 1302 patients undergoing invasive mechanical ventilation (1693 separate episodes of invasive mechanical ventilation) prior to and after institution of a standardized, goal-directed mechanical ventilation order set using a controlled before-and-after study design. Patient-specific goals for oxygenation partial pressure of oxygen in arterial blood (Pao 2 ), ARDS Network [Net] positive end-expiratory pressure [PEEP]/fraction of inspired oxygen [Fio 2 ] table use) and ventilation (pH, partial pressure of carbon dioxide) were selected by prescribers and implemented by RTs. Compliance with the new mechanical ventilation order set was high: 88.2% compliance versus 3.8% before implementation of the order set ( P < .001). Adherence to the PEEP/Fio 2 table after implementation of the order set was significantly greater (86.0% after vs 82.9% before, P = .02). There was no difference in duration of mechanical ventilation, intensive care unit (ICU) length of stay, and in-hospital or ICU mortality. A standardized best practice mechanical ventilation order set can be implemented by a multidisciplinary team and is associated with improved compliance to written orders and adherence to the ARDSNet PEEP/Fio 2 table.

Randomized controlled trial comparing nasal intermittent positive pressure ventilation and nasal continuous positive airway pressure in premature infants after tracheal extubation.

PubMed

Komatsu, Daniela Franco Rizzo; Diniz, Edna Maria de Albuquerque; Ferraro, Alexandre Archanjo; Ceccon, Maria Esther Jurvest Rivero; Vaz, Flávio Adolfo Costa

2016-09-01

To analyze the frequency of extubation failure in premature infants using conventional mechanical ventilation (MV) after extubation in groups subjected to nasal intermittent positive pressure ventilation (nIPPV) and continuous positive airway pressure (nCPAP). Seventy-two premature infants with respiratory failure were studied, with a gestational age (GA) ≤ 36 weeks and birth weight (BW) > 750 g, who required tracheal intubation and mechanical ventilation. The study was controlled and randomized in order to ensure that the members of the groups used in the research were chosen at random. Randomization was performed at the time of extubation using sealed envelopes. Extubation failure was defined as the need for re-intubation and mechanical ventilation during the first 72 hours after extubation. Among the 36 premature infants randomized to nIPPV, six (16.6%) presented extubation failure in comparison to 11 (30.5%) of the 36 premature infants randomized to nCPAP. There was no statistical difference between the two study groups regarding BW, GA, classification of the premature infant, and MV time. The main cause of extubation failure was the occurrence of apnea. Gastrointestinal and neurological complications did not occur in the premature infants participating in the study. We found that, despite the extubation failure of the group of premature infants submitted to nIPPV being numerically smaller than in premature infants submitted to nCPAP, there was no statistically significant difference between the two modes of ventilatory support after extubation.

Reabsorption atelectasis in a porcine model of ARDS: regional and temporal effects of airway closure, oxygen, and distending pressure.

PubMed

Derosa, Savino; Borges, João Batista; Segelsjö, Monica; Tannoia, Angela; Pellegrini, Mariangela; Larsson, Anders; Perchiazzi, Gaetano; Hedenstierna, Göran

2013-11-01

Little is known about the small airways dysfunction in acute respiratory distress syndrome (ARDS). By computed tomography (CT) imaging in a porcine experimental model of early ARDS, we aimed at studying the location and magnitude of peripheral airway closure and alveolar collapse under high and low distending pressures and high and low inspiratory oxygen fraction (FIO2). Six piglets were mechanically ventilated under anesthesia and muscle relaxation. Four animals underwent saline-washout lung injury, and two served as healthy controls. Beyond the site of assumed airway closure, gas was expected to be trapped in the injured lungs, promoting alveolar collapse. This was tested by ventilation with an FIO2 of 0.25 and 1 in sequence during low and high distending pressures. In the most dependent regions, the gas/tissue ratio of end-expiratory CT, after previous ventilation with FIO2 0.25 low-driving pressure, was significantly higher than after ventilation with FIO2 1; with high-driving pressure, this difference disappeared. Also, significant reduction in poorly aerated tissue and a correlated increase in nonaerated tissue in end-expiratory CT with FIO2 1 low-driving pressure were seen. When high-driving pressure was applied or after previous ventilation with FIO2 0.25 and low-driving pressure, this pattern disappeared. The findings suggest that low distending pressures produce widespread dependent airway closure and with high FIO2, subsequent absorption atelectasis. Low FIO2 prevented alveolar collapse during the study period because of slow absorption of gas behind closed airways.

10 CFR 54.21 - Contents of application-technical information.

Code of Federal Regulations, 2011 CFR

2011-01-01

...), motors, diesel generators, air compressors, snubbers, the control rod drive, ventilation dampers..., the reactor vessel, the reactor coolant system pressure boundary, steam generators, the pressurizer...

10 CFR 54.21 - Contents of application-technical information.

Code of Federal Regulations, 2010 CFR

2010-01-01

...), motors, diesel generators, air compressors, snubbers, the control rod drive, ventilation dampers..., the reactor vessel, the reactor coolant system pressure boundary, steam generators, the pressurizer...

Particle size concentration distribution and influences on exhaled breath particles in mechanically ventilated patients.

PubMed

Wan, Gwo-Hwa; Wu, Chieh-Liang; Chen, Yi-Fang; Huang, Sheng-Hsiu; Wang, Yu-Ling; Chen, Chun-Wan

2014-01-01

Humans produce exhaled breath particles (EBPs) during various breath activities, such as normal breathing, coughing, talking, and sneezing. Airborne transmission risk exists when EBPs have attached pathogens. Until recently, few investigations had evaluated the size and concentration distributions of EBPs from mechanically ventilated patients with different ventilation mode settings. This study thus broke new ground by not only evaluating the size concentration distributions of EBPs in mechanically ventilated patients, but also investigating the relationship between EBP level and positive expiratory end airway pressure (PEEP), tidal volume, and pneumonia. This investigation recruited mechanically ventilated patients, with and without pneumonia, aged 20 years old and above, from the respiratory intensive care unit of a medical center. Concentration distributions of EBPs from mechanically ventilated patients were analyzed with an optical particle analyzer. This study finds that EBP concentrations from mechanically ventilated patients during normal breathing were in the range 0.47-2,554.04 particles/breath (0.001-4.644 particles/mL). EBP concentrations did not differ significantly between the volume control and pressure control modes of the ventilation settings in the mechanically ventilated patients. The patient EBPs were sized below 5 µm, and 80% of them ranged from 0.3 to 1.0 µm. The EBPs concentrations in patients with high PEEP (> 5 cmH₂O) clearly exceeded those in patients with low PEEP (≤ 5 cmH₂O). Additionally, a significant negative association existed between pneumonia duration and EBPs concentration. However, tidal volume was not related to EBPs concentration.

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.

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.

Respirator triggering of electron-beam computed tomography (EBCT): differences in dynamic changes between augmented ventilation and controlled mechanical ventilation

NASA Astrophysics Data System (ADS)

Recheis, Wolfgang A.; Kleinsasser, Axel; Schuster, Antonius H.; Loeckinger, Alexander; Frede, Thomas; Springer, Peter; Hoermann, Christoph; zur Nedden, Dieter

2000-04-01

The purpose was to evaluate differences in dynamic changes of the lung aeration (air-tissue ratio) between augmented modes of ventilation (AMV) and controlled mechanical ventilation (CMV) in normal subjects. 4 volunteers, ventilated with the different respirator protocols via face mask, were scanned using the EBCT in the 50 ms mode. A software analyzed the respirator's digitized pressure and volume signals of two subsequent ventilation phases. Using these values it was possible to calculate the onset of inspiration or expiration of the next respiratory phase. The calculated starting point was then used to trigger the EBCT. The dynamic changes of air- tissue ratios were evaluated in three separate regions: a ventral, an intermediate and a dorsal area. AMV results in increase of air-tissue ratio in the dorsal lung area due to the active contraction of the diaphragm, whereas CMV results in a more pronounced increase in air-tissue ratio of the ventral lung area. This study gives further insight into the dynamic changes of the lung's biomechanics by comparing augmented ventilation and controlled mechanical ventilation in the healthy proband.

The effectiveness of nasal mask vs face mask ventilation in anesthetized, apneic pediatric subjects over 2 years of age: a randomized controlled trial.

PubMed

Itagaki, Taiga; Gubin, Tatyana A; Sayal, Puneet; Jiang, Yandong; Kacmarek, Robert M; Anderson, Thomas Anthony

2016-02-01

We hypothesized that anesthetized, apneic children could be ventilated equivalently or more efficiently by nasal mask ventilation (NMV) than face mask ventilation (FMV). The aim of this randomized controlled study was to test this hypothesis by comparing the expiratory tidal volume (Vte) between NMV and FMV. After the induction of anesthesia, 41 subjects, 3-17 years of age without anticipated difficult mask ventilation, were randomly assigned to receive either NMV or FMV with neck extension. Both groups were ventilated with pressure control ventilation (PCV) at 20 cmH2 O of peak inspiratory pressure (PIP) with positive end-expiratory pressure (PEEP) levels of 0, 5, and 10 cmH2 O. An additional mouth closing maneuver (MCM) was applied for the NMV group. The Vte was higher in the FMV group compared with the NMV group (median difference [95% CI]: 8.4 [5.5-11.6] ml·kg(-1) ; P < 0.001) when MCM was not applied. NMV achieved less PEEP than FMV (median difference [95% CI]: 5.0 [4.3-5.3] cmH2 O at 10 cmH2 O; P < 0.001) though both groups achieved the set PIP level. In the NMV group, MCM markedly increased Vte (median increase [95% CI]: 5.9 [2.5-9.0] ml·kg(-1) ; P < 0.005) and PEEP (median increase [95% CI]: 5.0 [0.6-8.6] cmH2 O at 10 cmH2 O; P < 0.005); however, PEEP was highly variable and lower than that of FMV (median difference [95% CI]: 2.5 [0.8-8.5] cmH2 O at 10 cmH2 O; P < 0.05). In anesthetized, apneic children greater than 2 years of age ventilated with an anesthesia ventilator and neck extension, FMV established a greater Vte than NMV regardless of mouth status. NMV could not maintain the set PEEP level due to an air leak from the mouth. The MCM increased the Vte and PEEP. © 2016 John Wiley & Sons Ltd.

Efficacy of a new device to optimize positive pressure ventilation via face mask in edentulous patients: a randomized trial.

PubMed

Niño, Maria C; Pauwels, Andres; Raffan, Fernando; Arango, Enrique; Romero, David J; Benitez, Daniel

2017-04-01

Mask ventilation is routinely performed during anesthesia. Under some circumstances, it might be difficult to perform, such as in edentulous patients, due to inadequate mask seal. We developed a new device called NIPARA and studied its use For ventilation optimization in edentulous patients. This randomized controlled trial included edentulous adults who had no other predictors of difficult airway, scheduled to undergo general anesthesia. Patients were assigned either to the NIPARA device group or to the control group (oral airway only). The primary outcomes were peak inspiratory pressure and tidal volume values of the first 14 breaths. The secondary outcome was the incidence of complications. Data from 37 patients were collected during a one-year period (twenty in the NIPARA device group and 17 in the control group). The difference in mean PIP was not statistically significant. The tidal volume was 1.5 times greater in the NIPARA group than in the control group. One patient from the intervention group had minimal oral trauma. In the administration of face mask ventilation, NIPARA is an effective device that significantly improves the tidal volume administered in edentulous patients.

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.

A study of the effect of nasal modes of ventilation on the incidence of gastro-oesophageal reflux in preterm neonates.

PubMed

Mathai, Ss; Datta, Karuna; Adhikari, Km

2012-01-01

Nasal modes of respiratory support cause variable amounts of gastric dilatation which may increase gastro-oesophageal reflux (GER) in preterms. To compare the incidence of GER in nasally ventilated, preterm babies with controls (babies not on ventilation). A prospective, observational comparative study. Twenty-three preterm babies of gestational age 28-36 weeks and weight ranging between 1,000 g and < 2,500 g on either nasal continuous positive airway pressure (nCPAP) or nasal intermittent positive pressure venti-lation (nIPPV) were assessed for GER. They were compared with controls not on ventilation some of who were test babies when off ventilation (subgroup A) and some were unrelated babies not on ventilator but matched for gestational age and weight with test babies (subgroup B). All babies were subjected to continuous, oesophageal pH monitoring with dual sensor (upper and lower oesophageal) catheters. Reflux index (RI) was calculated as the percentage of study time the lower oesophageal pH was < 4. Primary outcome was the RI in the test and controls groups. Secondary outcome was the temporal relation of the reflux with symptoms if any. Numerical data were shown as mean with standard deviation and statistical comparisons were done using the χ(2)-test, Fischer test, and t-test wherever applicable. The RI was higher in ventilated babies as compared to the control group, particularly in the subgroup A, where test babies formed their own controls. Grade IV reflux (7 cases) was seen only in the ventilated babies. There was no difference in the incidence of GER in babies on nCPAP as compared with nIPPV. Grade IV reflux could not be reliably predicted by RI alone. No definite temporal relation between episodes of reflux and symptoms could be determined in this study. There is an increase in GER in preterms on nasal modes of ventilation. A combination of upper (pharyngeal) and lower oesophageal sensors are preferred to a single lower oesophageal sensor when assessing GER by oesophageal pHmetry in neonates.

Multicentre randomised controlled trial to investigate the usefulness of continuous pneumatic regulation of tracheal cuff pressure for reducing ventilator-associated pneumonia in mechanically ventilated severe trauma patients: the AGATE study protocol

PubMed Central

Marjanovic, Nicolas; Frasca, Denis; Asehnoune, Karim; Paugam, Catherine; Lasocki, Sigismond; Ichai, Carole; Lefrant, Jean-Yves; Leone, Marc; Dahyot-Fizelier, Claire; Pottecher, Julien; Falcon, Dominique; Veber, Benoit; Constantin, Jean-Michel; Seguin, Sabrina; Guénézan, Jérémy; Mimoz, Olivier

2017-01-01

Introduction Severe trauma represents the leading cause of mortality worldwide. While 80% of deaths occur within the first 24 hours after trauma, 20% occur later and are mainly due to healthcare-associated infections, including ventilator-associated pneumonia (VAP). Preventing underinflation of the tracheal cuff is recommended to reduce microaspiration, which plays a major role in the pathogenesis of VAP. Automatic devices facilitate the regulation of tracheal cuff pressure, and their implementation has the potential to reduce VAP. The objective of this work is to determine whether continuous regulation of tracheal cuff pressure using a pneumatic device reduces the incidence of VAP compared with intermittent control in severe trauma patients. Methods and analysis This multicentre randomised controlled and open-label trial will include patients suffering from severe trauma who are admitted within the first 24 hours, who require invasive mechanical ventilation to longer than 48 hours. Their tracheal cuff pressure will be monitored either once every 8 hours (control group) or continuously using a pneumatic device (intervention group). The primary end point is the proportion of patients that develop VAP in the intensive care unit (ICU) at day 28. The secondary end points include the proportion of patients that develop VAP in the ICU, early (≤7 days) or late (>7 days) VAP, time until the first VAP diagnosis, the number of ventilator-free days and antibiotic-free days, the length of stay in the ICU, the proportion of patients with ventilator-associated events and that die during their ICU stay. Ethics and dissemination This protocol has been approved by the ethics committee of Poitiers University Hospital, and will be carried out according to the principles of the Declaration of Helsinki and the Good Clinical Practice guidelines. The results of this study will be disseminated through presentation at scientific conferences and publication in peer-reviewed journals. Trial registration Clinical Trials NCT02534974 PMID:28790042

Multicentre randomised controlled trial to investigate the usefulness of continuous pneumatic regulation of tracheal cuff pressure for reducing ventilator-associated pneumonia in mechanically ventilated severe trauma patients: the AGATE study protocol.

PubMed

Marjanovic, Nicolas; Frasca, Denis; Asehnoune, Karim; Paugam, Catherine; Lasocki, Sigismond; Ichai, Carole; Lefrant, Jean-Yves; Leone, Marc; Dahyot-Fizelier, Claire; Pottecher, Julien; Falcon, Dominique; Veber, Benoit; Constantin, Jean-Michel; Seguin, Sabrina; Guénézan, Jérémy; Mimoz, Olivier

2017-08-07

Severe trauma represents the leading cause of mortality worldwide. While 80% of deaths occur within the first 24 hours after trauma, 20% occur later and are mainly due to healthcare-associated infections, including ventilator-associated pneumonia (VAP). Preventing underinflation of the tracheal cuff is recommended to reduce microaspiration, which plays a major role in the pathogenesis of VAP. Automatic devices facilitate the regulation of tracheal cuff pressure, and their implementation has the potential to reduce VAP. The objective of this work is to determine whether continuous regulation of tracheal cuff pressure using a pneumatic device reduces the incidence of VAP compared with intermittent control in severe trauma patients. This multicentre randomised controlled and open-label trial will include patients suffering from severe trauma who are admitted within the first 24 hours, who require invasive mechanical ventilation to longer than 48 hours. Their tracheal cuff pressure will be monitored either once every 8 hours (control group) or continuously using a pneumatic device (intervention group). The primary end point is the proportion of patients that develop VAP in the intensive care unit (ICU) at day 28. The secondary end points include the proportion of patients that develop VAP in the ICU, early (≤7 days) or late (>7 days) VAP, time until the first VAP diagnosis, the number of ventilator-free days and antibiotic-free days, the length of stay in the ICU, the proportion of patients with ventilator-associated events and that die during their ICU stay. This protocol has been approved by the ethics committee of Poitiers University Hospital, and will be carried out according to the principles of the Declaration of Helsinki and the Good Clinical Practice guidelines. The results of this study will be disseminated through presentation at scientific conferences and publication in peer-reviewed journals. Clinical Trials NCT02534974. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Space Suit Portable Life Support System Rapid Cycle Amine Repackaging and Sub-Scale Test Results

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Rivera, Fatonia L.

2010-01-01

NASA is developing technologies to meet requirements for an extravehicular activity (EVA) Portable Life Support System (PLSS) for exploration. The PLSS Ventilation Subsystem transports clean, conditioned oxygen to the pressure garment for space suit pressurization and human consumption, and recycles the ventilation gas, removing carbon dioxide, humidity, and trace contaminants. This paper provides an overview of the development efforts conducted at the NASA Johnson Space Center to redesign the Rapid Cycle Amine (RCA) canister and valve assembly into a radial flow, cylindrical package for carbon dioxide and humidity control of the PLSS ventilation loop. Future work is also discussed.

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.

Control technology for integrated circuit fabrication at Micro-Circuit Engineering, Incorporated, West Palm Beach, Florida

NASA Astrophysics Data System (ADS)

Mihlan, G. I.; Mitchell, R. I.; Smith, R. K.

1984-07-01

A survey to assess control technology for integrated circuit fabrication was conducted. Engineering controls included local and general exhaust ventilation, shielding, and personal protective equipment. Devices or work stations that contained toxic materials that were potentially dangerous were controlled by local exhaust ventilation. Less hazardous areas were controlled by general exhaust ventilation. Process isolation was used in the plasma etching, low pressure chemical vapor deposition, and metallization operations. Shielding was used in ion implantation units to control X-ray emissions, in contact mask alignes to limit ultraviolet (UV) emissions, and in plasma etching units to control radiofrequency and UV emissions. Most operations were automated. Use of personal protective equipment varied by job function.

Analysis on ventilation pressure of fire area in longitudinal ventilation of underground tunnel

NASA Astrophysics Data System (ADS)

Li, Jiaxin; Li, Yanfeng; Feng, Xiao; Li, Junmei

2018-03-01

In order to solve the problem of ventilation pressure loss in the fire area under the fire condition, the wind pressure loss model of the fire area is established based on the thermodynamic equilibrium relation. The semi-empirical calculation formula is obtained by using the model experiment and CFD simulation. The validity of the formula is verified. The results show that the ventilation pressure loss in the fire zone is proportional to the convective heat release rate at the critical velocity, which is inversely proportional to the upstream ventilation velocity and the tunnel cross-sectional area. The proposed formula is consistent with the law of the tunnel fire test fitting formula that results are close, in contrast, the advantage lies in a clear theoretical basis and ventilation velocity values. The resistance of road tunnel ventilation system is calculated accurately and reliably, and then an effective emergency ventilation operation program is developed. It is necessary to consider the fire zone ventilation pressure loss. The proposed ventilation pressure loss formula can be used for design calculation after thorough verification.

Ventilation by high-frequency chest wall compression in dogs with normal lungs.

PubMed

Zidulka, A; Gross, D; Minami, H; Vartian, V; Chang, H K

1983-06-01

In 6 anesthetized and paralyzed supine dogs, ventilation by high-frequency chest wall compression (HFCWC) was accomplished by a piston pump rapidly oscillating the pressure in a modified double blood pressure cuff wrapped around the lower thorax. Testing applied frequencies at 3, 5, 8, and 11 Hz, applied peak cuff pressures ranged from 30 to 230 cmH2O. This produced swings of esophageal pressure as high as 18 cmH2O and peak oscillatory air flow ranging from 0.7 to 1.6 L/s. Oscillatory tidal volume declined with increasing frequency and ranged from a mean of 61 to 45 ml. After 30 min of applied HFCWC, arterial blood gas determinations revealed a mean PaCO2 of 29.3 mmHg at 5 Hz, 35 mmHg at 3 Hz, 36 mmHg at 8 Hz, and 51 mmHg at 11 Hz. Mean PaO2 improved from ventilator control values at 3 Hz, remained unchanged at 5 and 8 Hz, and declined at 11 Hz. In 2 dogs breathing spontaneously, HFCWC applied at 5 and 11 Hz resulted in a reduction in spontaneous minute ventilation, mainly by a reduction in spontaneous tidal volume, whereas arterial blood gas values changed slightly. One dog ceased to breath spontaneously within 5 min of application of HFCWC as the PaCO2 fell below control values. We conclude that in dogs with normal lungs, HFCWC may assist spontaneous ventilation. In paralyzed dogs, HFCWC may be of sufficient magnitude to cause hyperventilation.

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).

Ventilation practices in the neonatal intensive care unit: a cross-sectional study.

PubMed

van Kaam, Anton H; Rimensberger, Peter C; Borensztajn, Dorine; De Jaegere, Anne P

2010-11-01

To assess current ventilation practices in newborn infants. We conducted a 2-point cross-sectional study in 173 European neonatal intensive care units, including 535 infants (mean gestational age 28 weeks and birth weight 1024 g). Patient characteristics, ventilator settings, and measurements were collected bedside from endotracheally ventilated infants. A total of 457 (85%) patients were conventionally ventilated. Time cycled pressure-limited ventilation was used in 59% of these patients, most often combined with synchronized intermittent mandatory ventilation (51%). Newer conventional ventilation modes like volume targeted and pressure support ventilation were used in, respectively, 9% and 7% of the patients. The mean tidal volume, measured in 84% of the conventionally ventilated patients, was 5.7 ± 2.3 ml/kg. The mean positive end-expiratory pressure was 4.5 ± 1.1 cmH(2)O and rarely exceeded 7 cmH(2)O. Time cycled pressure-limited ventilation is the most commonly used mode in neonatal ventilation. Tidal volumes are usually targeted between 4 to 7 mL/kg and positive end-expiratory pressure between 4 to 6 cmH(2)O. Newer ventilation modes are only used in a minority of patients. Copyright © 2010 Mosby, Inc. All rights reserved.

[Appropriate dust control measures for jade carving operations].

PubMed

Liu, Jiang; Wang, Qiushui; Liu, Guangquan

2002-12-01

To provide the appropriate dust control measures for jade carving operations. Dust concentrations in the workplace were measured according to GB/T 5748-85. Ventilation system of dust control were measured according to GB/T 16157-1996. Dust particle size distributions for different sources and particle size fraction collecting efficiencies of the dust collectors were measured with WY-1 in-stack 7 stage cascade impactors. On the basis of adopting wet process in the carving operations, local exhaust ventilation system for dust control was installed, which included: the special designed slot exhaust hoods with hood face velocity of 2.5 m/s and exhaust volume of 600 m3/h. The pipe sizes were determined according to the air volume passing through the pipe and the reasonable air velocities. Impinging scrubber or bag filter dust collector were selected to treat the dust laden air from the local exhaust ventilation system, which gave a total collecting efficiency of 97% for impinging scrubber and 98% for bag filter; The type of fan and its size were selected according to the total air volume of the ventilation system and maximum total pressure needed for the longest pipe line plus the pressure drop of the dust collector. Practical application showed that, after installation and use of the appropriate dust control measures, the dust concentrations in the workplaces could meet or nearly meet the national hygienic standard and the dust laden air at the local exhaust ventilation system could meet the national emission standard.

Buildings operations and ETS exposure.

PubMed Central

Spengler, J D

1999-01-01

Mechanical systems are used in buildings to provide conditioned air, dissipate thermal loads, dilute contaminants, and maintain pressure differences. The characteristics of these systems and their operations h implications for the exposures of workers to environmental tobacco smoke (ETS) and for the control of these exposures. This review describes the general features of building ventilation systems and the efficacy of ventilation for controlling contaminant concentrations. Ventilation can reduce the concentration of ETS through dilution, but central heating, ventilating, and air conditioning (HVAC) can also move air throughout a building that has been contaminated by ETS. An understanding of HVAC systems is needed to develop models for exposures of workers to ETS. Images Figure 1 Figure 2 Figure 3 PMID:10375293

Continuous positive airway pressure and ventilation are more effective with a nasal mask than a full face mask in unconscious subjects: a randomized controlled trial.

PubMed

Oto, Jun; Li, Qian; Kimball, William R; Wang, Jingping; Sabouri, Abdolnabi S; Harrell, Priscilla G; Kacmarek, Robert M; Jiang, Yandong

2013-12-23

Upper airway obstruction (UAO) is a major problem in unconscious subjects, making full face mask ventilation difficult. The mechanism of UAO in unconscious subjects shares many similarities with that of obstructive sleep apnea (OSA), especially the hypotonic upper airway seen during rapid eye movement sleep. Continuous positive airway pressure (CPAP) via nasal mask is more effective at maintaining airway patency than a full face mask in patients with OSA. We hypothesized that CPAP via nasal mask and ventilation (nCPAP) would be more effective than full face mask CPAP and ventilation (FmCPAP) for unconscious subjects, and we tested our hypothesis during induction of general anesthesia for elective surgery. In total, 73 adult subjects requiring general anesthesia were randomly assigned to one of four groups: nCPAP P0, nCPAP P5, FmCPAP P0, and FmCPAP P5, where P0 and P5 represent positive end-expiratory pressure (PEEP) 0 and 5 cm H2O applied prior to induction. After apnea, ventilation was initiated with pressure control ventilation at a peak inspiratory pressure over PEEP (PIP/PEEP) of 20/0, then 20/5, and finally 20/10 cm H2O, each applied for 1 min. At each pressure setting, expired tidal volume (Vte) was calculated by using a plethysmograph device. The rate of effective tidal volume (Vte > estimated anatomical dead space) was higher (87.9% vs. 21.9%; P<0.01) and the median Vte was larger (6.9 vs. 0 mL/kg; P<0.01) with nCPAP than with FmCPAP. Application of CPAP prior to induction of general anesthesia did not affect Vte in either approach (nCPAP pre- vs. post-; 7.9 vs. 5.8 mL/kg, P = 0.07) (FmCPAP pre- vs. post-; 0 vs. 0 mL/kg, P = 0.11). nCPAP produced more effective tidal volume than FmCPAP in unconscious subjects. ClinicalTrials.gov identifier: NCT01524614.

Bi-level positive pressure ventilation and adaptive servo ventilation in patients with heart failure and Cheyne-Stokes respiration.

PubMed

Fietze, Ingo; Blau, Alexander; Glos, Martin; Theres, Heinz; Baumann, Gert; Penzel, Thomas

2008-08-01

Nocturnal positive pressure ventilation (PPV) has been shown to be effective in patients with impaired left ventricular ejection fraction (LVEF) and Cheyne-Stokes respiration (CSR). We investigated the effect of a bi-level PPV and adaptive servo ventilation on LVEF, CSR, and quantitative sleep quality. Thirty-seven patients (New York heart association [NYHA] II-III) with LVEF<45% and CSR were investigated by electrocardiography (ECG), echocardiography and polysomnography. The CSR index (CSRI) was 32.3+/-16.2/h. Patients were randomly treated with bi-level PPV using the standard spontaneous/timed (S/T) mode or with adaptive servo ventilation mode (AutoSetCS). After 6 weeks, 30 patients underwent control investigations with ECG, echocardiography, and polysomnography. The CSRI decreased significantly to 13.6+/-13.4/h. LVEF increased significantly after 6 weeks of ventilation (from 25.1+/-8.5 to 28.8+/-9.8%, p<0.01). The number of respiratory-related arousals decreased significantly. Other quantitative sleep parameters did not change. The Epworth sleepiness score improved slightly. Daytime blood pressure and heart rate did not change. There were some differences between bi-level PPV and adaptive servo ventilation: the CSRI decreased more in the AutoSetCS group while the LVEF increased more in the bi-level PPV group. Administration of PPV can successfully attenuate CSA. Reduced CSA may be associated with improved LVEF; however, this may depend on the mode of PPV. Changed LVEF is evident even in the absence of significant changes in blood pressure.

[Guide for the use of jet-ventilation during ENT and oral surgery].

PubMed

Bourgain, J-L; Chollet, M; Fischler, M; Gueret, G; Mayne, A

2010-10-01

The aim of this synthesis was to give recommendations on the use of jet-ventilation during ENT surgical and endoscopy procedures. Literature was collected from PUBMED and analysed by the members of French association of anaesthesiologists in ENT surgery, all skilled in this field. Presentation of these recommendations was given during the general assembly held in Reims, the 15th May 2009. Jet-ventilation is especially indicated during upper airway endoscopy and laryngeal invasive endoscopic surgery. Furthermore, transtracheal jet ventilation is included on most of difficult oxygenation and difficult intubation algorithm. The main risk of jet-ventilation is pulmonary barotrauma when expiration of injected gas is impeded by an upper airway obstruction. Failure and complications of tracheal puncture are rare when performed by experimented operators. Clinical use of jet ventilation requires a dedicated device. Practice of jet ventilation without intubation may be dangerous when applied without control of driving pressure and end expiratory tracheal pressure. Every anaesthetist should be familiar with transtracheal ventilation since they may face a "cannot ventilate cannot intubate" situation. Upper airway endoscopy and laryngeal surgery are the ideal field for training jet ventilation, even more so as this technique offers perfect operative conditions. To apply this project, jet ventilation should be used more frequently in routine practice. To maintain skill, regular use of these techniques is required. Copyright © 2010 Elsevier Masson SAS. All rights reserved.

Effect of nature-based sounds' intervention on agitation, anxiety, and stress in patients under mechanical ventilator support: a randomised controlled trial.

PubMed

Saadatmand, Vahid; Rejeh, Nahid; Heravi-Karimooi, Majideh; Tadrisi, Sayed Davood; Zayeri, Farid; Vaismoradi, Mojtaba; Jasper, Melanie

2013-07-01

Few studies have been conducted to investigate the effect of nature-based sounds (N-BS) on agitation, anxiety level and physiological signs of stress in patients under mechanical ventilator support. Non-pharmacological nursing interventions such as N-BS can be less expensive and efficient ways to alleviate anxiety and adverse effects of sedative medications in patients under mechanical ventilator support. This study was conducted to identify the effect of the nature-based sounds' intervention on agitation, anxiety level and physiological stress responses in patients under mechanical ventilation support. A randomized placebo-controlled trial design was used to conduct this study. A total of 60 patients aged 18-65 years under mechanical ventilation support in an intensive care unit were randomly assigned to the control and experimental groups. The patients in the intervention group received 90 min of N-BS. Pleasant nature sounds were played to the patients using media players and headphones. Patients' physiological signs were taken immediately before the intervention and at the 30th, 60th, 90th minutes and 30 min after the procedure had finished. The physiological signs of stress assessed were heart rate, respiratory rate, and blood pressure. Data were collected over eight months from Oct 2011 to June 2012. Anxiety levels and agitation were assessed using the Faces Anxiety Scale and Richmond Agitation Sedation Scale, respectively. The experimental group had significantly lower systolic blood pressure, diastolic blood pressure, anxiety and agitation levels than the control group. These reductions increased progressively in the 30th, 60th, 90th minutes, and 30 min after the procedure had finished indicating a cumulative dose effect. N-BS can provide an effective method of decreasing potentially harmful physiological responses arising from anxiety in mechanically ventilated patients. Nurses can incorporate N-BS intervention as a non-pharmacologic intervention into the daily care of patients under mechanical ventilation support in order to reduce their stress and anxiety. Copyright © 2012 Elsevier Ltd. All rights reserved.

Prone versus supine position in mechanically ventilated children: a pilot study.

PubMed

Sawhney, Ashu; Kumar, Nirmal; Sreenivas, Vishnubhatla; Gupta, Sangeeta; Tyagi, Vineet; Puliyel, Jacob M

2005-05-01

It is known that mechanically ventilated patients in the prone position have improved oxygenation compared with those supine. We did a prospective, randomized, controlled trial to evaluate the effect of prone position during mechanical ventilation, on survival in critically ill children. Forty-two children needing mechanical ventilation for various illnesses were randomized to receive initial ventilation for four hours prone or supine by drawing lots. Initial severity of illness and blood gases in all children were noted. In a crossover design, after the initial four hours the children were turned over and ventilated in the alternate posture for an hour. Oxygenation parameters and mean airway pressures were noted at one hour, four hours, and five hours. Mortality, duration of ventilation, and the above parameters were compared in the two groups. Initial PRISM scores were similar in the two groups. Mortality in the prone group was less than in the supine group. The odds ratio of mortality was 0.20 (95% CI 0.05-0.75). Duration of ventilation was similar in the two groups. The oxygenation index was significantly lower in the prone group at one, four, and five hours after onset of ventilation. Prone position in the first few hours of ventilation significantly improves gas exchange and oxygenation, reduces the mean airway pressures required to ventilate children, and may cause significant improvement in survival. Our study protocol allowed ventilator settings to be changed as needed during ventilation.

Advanced positive airway pressure modes: adaptive servo ventilation and volume assured pressure support.

PubMed

Selim, Bernardo; Ramar, Kannan

2016-09-01

Volume assured pressure support (VAPS) and adaptive servo ventilation (ASV) are non-invasive positive airway pressure (PAP) modes with sophisticated negative feedback control systems (servomechanism), having the capability to self-adjust in real time its respiratory controlled variables to patient's respiratory fluctuations. However, the widespread use of VAPS and ASV is limited by scant clinical experience, high costs, and the incomplete understanding of propriety algorithmic differences in devices' response to patient's respiratory changes. Hence, we will review and highlight similarities and differences in technical aspects, control algorithms, and settings of each mode, focusing on the literature search published in this area. One hundred twenty relevant articles were identified by Scopus, PubMed, and Embase databases from January 2010 to 2016, using a combination of MeSH terms and keywords. Articles were further supplemented by pearling. Recommendations were based on the literature review and the authors' expertise in this area. Expert commentary: ASV and VAPS differ in their respiratory targets and response to a respiratory fluctuation. The VAPS mode targets a more consistent minute ventilation, being recommended in the treatment of sleep related hypoventilation disorders, while ASV mode attempts to provide a more steady breathing airflow pattern, treating successfully most central sleep apnea syndromes.

[Study of setting of ventilator volume tidal and airway pressure alarm threshold with continuous extra-sternum heart compression in cardiopulmonary resuscitation].

PubMed

Luo, Jian-yu; Wang, Xiao-yuan; Cai, Tian-bin; Jiang, Wen-fang

2013-02-01

To investigate the setting of ventilator volume tidal (VT) and airway pressure alarm threshold during cardiopulmonary resuscitation (CPR) by continuous extra-sternum heart compression. Forty cases with respiration and cardiac arrest in the department of critical care medicine were randomly divided into low VT ventilation group and conventional VT group. Both groups were given the volume control mode. In the low VT ventilation group, VT was set on 6 - 7 ml/kg, and high pressure alarm threshold was adjusted to 60 cm H2O by the conventional 40 cm H2O during CPR. In the conventional VT group, VT and high pressure alarm threshold were set at 8 - 12 ml/kg and 40 cm H2O, respectively. Real-time actual VT, peak inspiratory pressure (PIP), and arterial blood gas test, blood lactic acid at 10 minutes and 30 minutes after CPR were observed. At 10 minutes after CPR, in the low VT ventilation group, arterial blood pH, arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2), HCO3(-), arterial oxygen saturation (SaO2) and blood lactic acid were better as compared with those in the conventional VT ventilation group (pH: 7.21±0.09 vs. 7.13±0.07, PaO2: 45.35±5.92 mm Hg vs. 40.70±4.70 mm Hg, PaCO2: 57.10±7.59 mm Hg vs. 61.60±5.47 mm Hg, HCO3(-): 18.50±3.50 mmol/L vs. 14.75±2.65 mmol/L, SaO2: 0.796±0.069 vs. 0.699±0.066, blood lactic acid: 7.07±1.60 mmol/L vs. 8.13±1.56 mmol/L, all P<0.05). The success rate of resuscitation in the low VT ventilation group was higher than that of the conventional VT ventilation group (45% vs. 15%, P<0.05), and PIP (cm H2O) of low VT ventilation group was lower than that of the conventional VT group (37.25±7.99 cm H2O vs. 42.70±7.40 cm H2O, P<0.05). In all the patients in both groups barotrauma did not occur. The strategy of low ventilator VT (6 - 7 ml/kg) with appropriate elevation of airway pressure alarm threshold was better than that of conventional ventilation setting, with no increase in incidence of barotraumas during CPR.

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.

The course of lung inflation alters the central pattern of tracheobronchial cough in cat-The evidence for volume feedback during cough.

PubMed

Poliacek, Ivan; Simera, Michal; Veternik, Marcel; Kotmanova, Zuzana; Pitts, Teresa; Hanacek, Jan; Plevkova, Jana; Machac, Peter; Visnovcova, Nadezda; Misek, Jakub; Jakus, Jan

2016-07-15

The effect of volume-related feedback and output airflow resistance on the cough motor pattern was studied in 17 pentobarbital anesthetized spontaneously-breathing cats. Lung inflation during tracheobronchial cough was ventilator controlled and triggered by the diaphragm electromyographic (EMG) signal. Altered lung inflations during cough resulted in modified cough motor drive and temporal features of coughing. When tidal volume was delivered (via the ventilator) there was a significant increase in the inspiratory and expiratory cough drive (esophageal pressures and EMG amplitudes), inspiratory phase duration (CTI), total cough cycle duration, and the duration of all cough related EMGs (Tactive). When the cough volume was delivered (via the ventilator) during the first half of inspiratory period (at CTI/2-early over inflation), there was a significant reduction in the inspiratory and expiratory EMG amplitude, peak inspiratory esophageal pressure, CTI, and the overlap between inspiratory and expiratory EMG activity. Additionally, there was significant increase in the interval between the maximum inspiratory and expiratory EMG activity and the active portion of the expiratory phase (CTE1). Control inflations coughs and control coughs with additional expiratory resistance had increased maximum expiratory esophageal pressure and prolonged CTE1, the duration of cough abdominal activity, and Tactive. There was no significant difference in control coughing and/or control coughing when sham ventilation was employed. In conclusion, modified lung inflations during coughing and/or additional expiratory airflow resistance altered the spatio-temporal features of cough motor pattern via the volume related feedback mechanism similar to that in breathing. Copyright © 2016. Published by Elsevier B.V.

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...

An experimental study of an adaptive-wall wind tunnel

NASA Technical Reports Server (NTRS)

Celik, Zeki; Roberts, Leonard

1988-01-01

A series of adaptive wall ventilated wind tunnel experiments was carried out to demonstrate the feasibility of using the side wall pressure distribution as the flow variable for the assessment of compatibility with free air conditions. Iterative and one step convergence methods were applied using the streamwise velocity component, the side wall pressure distribution and the normal velocity component in order to investigate their relative merits. The advantage of using the side wall pressure as the flow variable is to reduce the data taking time which is one the major contributors to the total testing time. In ventilated adaptive wall wind tunnel testing, side wall pressure measurements require simple instrumentation as opposed to the Laser Doppler Velocimetry used to measure the velocity components. In ventilated adaptive wall tunnel testing, influence coefficients are required to determine the pressure corrections in the plenum compartment. Experiments were carried out to evaluate the influence coefficients from side wall pressure distributions, and from streamwise and normal velocity distributions at two control levels. Velocity measurements were made using a two component Laser Doppler Velocimeter system.

New Technologies and Materials for Enhanced Damage and Fire Tolerance of Naval Vessels

DTIC Science & Technology

2011-02-01

have already been used on naval vessels. However, their incorporation into fire and damage control systems has not progressed past the prototype...have an important role to play in enhancing fire suppression capabilities onboard ships. One is ventilation control . It can be used to isolate a...complicated than those for a dedicated system. Positive pressure ventilation and the use of the ship board HVAC trunking to control the spread of smoke

[Possibilities of bi-level positive pressure ventilation in chronic hypoventilation].

PubMed

Saaresranta, Tarja; Anttalainen, Ulla; Polo, Olli

2011-01-01

During the last decade, noninvasive bi-level positive pressure ventilation has enabled respiratory support in inpatient wards and at home. In many cases, a bi-level airway pressure ventilator can be used to avoid artificial airway and respirator therapy, and may shorten hospital stay and save costs. The treatment alleviates the patient's dyspnea and fatigue, whereby the quality of life improves, and in certain situations also the life span increases. The implementation of bi-level positive pressure ventilation by the physician requires knowledge of the basics of respiratory physiology and familiarization with the bi-level airway pressure ventilator.

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.

Reflexology: its effects on physiological anxiety signs and sedation needs.

PubMed

Akin Korhan, Esra; Khorshid, Leyla; Uyar, Mehmet

2014-01-01

To investigate whether reflexology has an effect on the physiological signs of anxiety and level of sedation in patients receiving mechanically ventilated support, a single blinded, randomized controlled design with repeated measures was used in the intensive care unit of a university hospital in Turkey. Patients (n = 60) aged between 18 and 70 years and were hospitalized in the intensive care unit and receiving mechanically ventilated support. Participants were randomized to a control group or an intervention group. The latter received 30 minutes of reflexology therapy on their feet, hands, and ears for 5 days. Subjects had vital signs taken immediately before the intervention and at the 10th, 20th, and 30th minutes of the intervention. In the collection of the data, "American Association of Critical-Care Nurses Sedation Assessment Scale" was used. The reflexology therapy group had a significantly lower heart rate, systolic blood pressure, diastolic blood pressure, and respiratory rate than the control group. A statistically significant difference was found between the averages of the scores that the patients included in the experimental and control groups received from the agitation, anxiety, sleep, and patient-ventilator synchrony subscales of the American Association of Critical-Care Nurses Sedation Assessment Scale. Reflexology can serve as an effective method of decreasing the physiological signs of anxiety and the required level of sedation in patients receiving mechanically ventilated support. Nurses who have appropriate training and certification may include reflexology in routine care to reduce the physiological signs of anxiety of patients receiving mechanical ventilation.

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

Ultrasonographic Evaluation of Diaphragm Thickness During Mechanical Ventilation in Intensive Care Patients.

PubMed

Francis, Colin Anthony; Hoffer, Joaquín Andrés; Reynolds, Steven

2016-01-01

Mechanical ventilation is associated with atrophy and weakness of the diaphragm. Ultrasound is an easy noninvasive way to track changes in thickness of the diaphragm. To validate ultrasound as a means of tracking thickness of the diaphragm in patients undergoing mechanical ventilation by evaluating interobserver and interoperator reliability and to collect initial data on the relationship of mode of ventilation to changes in the diaphragm. Daily ultrasound images of the quadriceps and the right side of the diaphragm were acquired in 8 critically ill patients receiving various modes of mechanical ventilation. Thickness of the diaphragm and the quadriceps was measured, and changes with time were noted. Interoperator and interobserver reliability were measured. Intraclass correlation coefficients between operators and between observers for thickness of the diaphragm and quadriceps were greater than 0.95, indicating excellent interoperator and interobserver reliability. Patients receiving assist-control ventilation (n = 4) showed a mean decline in diaphragm thickness of 4.7% per day. Patients receiving pressure support ventilation (n = 8) showed a mean increase in diaphragm thickness of 1.5% per day. Quadriceps thickness declined in all participants (n = 8) at a mean rate of 2.0% per day. Use of ultrasound to measure thickness of the diaphragm in 8 intensive care patients undergoing various modes of mechanical ventilation was feasible and yielded reproducible results. Ultrasound tracking of changes in thickness of the diaphragm in this small sample indicated that the thickness decreased during assist-control mode and increased during pressure support mode. ©2016 American Association of Critical-Care Nurses.

Impact of a VAP bundle in Belgian intensive care units.

PubMed

Jadot, Laurent; Huyghens, Luc; De Jaeger, Annick; Bourgeois, Marc; Biarent, Dominique; Higuet, Adeline; de Decker, Koen; Vander Laenen, Margot; Oosterlynck, Baudewijn; Ferdinande, Patrick; Reper, Pascal; Brimioulle, Serge; Van Cromphaut, Sophie; De Clety, Stéphane Clement; Sottiaux, Thierry; Damas, Pierre

2018-05-21

In order to decrease the incidence of ventilator-associated pneumonia (VAP) in Belgium, a national campaign for implementing a VAP bundle involving assessment of sedation, cuff pressure control, oral care with chlorhexidine and semirecumbent position, was launched in 2011-2012. This report will document the impact of this campaign. On 1 day, once a year from 2010 till 2016, except in 2012, Belgian ICUs were questioned about their ventilated patients. For each of these, data about the application of the bundle and the possible treatment for VAP were recorded. Between 36.6 and 54.8% of the 120 Belgian ICUs participated in the successive surveys. While the characteristics of ventilated patients remained similar throughout the years, the percentage of ventilated patients and especially the duration of ventilation significantly decreased before and after the national VAP bundle campaign. Ventilator care also profoundly changed: Controlling cuff pressure, head positioning above 30° were obtained in more than 90% of cases. Oral care was more frequently performed within a day, using more concentrated solutions of chlorhexidine. Subglottic suctioning also was used but in only 24.7% of the cases in the last years. Regarding the prevalence of VAP, it significantly decreased from 28% of ventilated patients in 2010 to 10.1% in 2016 (p ≤ 0.0001). Although a causal relationship cannot be inferred from these data, the successive surveys revealed a potential impact of the VAP bundle campaign on both the respiratory care of ventilated patients and the prevalence of VAP in Belgian ICUs encouraging them to follow the guidelines.

Physiological Effects of Positive Pressure Ventilation.

DTIC Science & Technology

1992-05-01

function in the patient with respiratory failure . In R. R. Kirby, M. J. Banner, & J. B. Downs (Eds.), Clinical Applications of Ventilatory Su2Rort (pp. 301...G., Blehschmidt, N. G., & Linder, W. J. (1990). Positive-pressure ventilation with positive end-expiratory pressure and atrial natriuretic peptide ...Acute Resniratorv Failure . New York: Churchill Livingstone. Ventilation 1 Physiological Effects of Positive Pressure Ventilation Dennis L. Oakes, RN, BSN

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.

Liquid- and air-filled catheters without balloon as an alternative to the air-filled balloon catheter for measurement of esophageal pressure.

PubMed

Beda, Alessandro; Güldner, Andreas; Carvalho, Alysson R; Zin, Walter Araujo; Carvalho, Nadja C; Huhle, Robert; Giannella-Neto, Antonio; Koch, Thea; de Abreu, Marcelo Gama

2014-01-01

Measuring esophageal pressure (Pes) using an air-filled balloon catheter (BC) is the common approach to estimate pleural pressure and related parameters. However, Pes is not routinely measured in mechanically ventilated patients, partly due to technical and practical limitations and difficulties. This study aimed at comparing the conventional BC with two alternative methods for Pes measurement, liquid-filled and air-filled catheters without balloon (LFC and AFC), during mechanical ventilation with and without spontaneous breathing activity. Seven female juvenile pigs (32-42 kg) were anesthetized, orotracheally intubated, and a bundle of an AFC, LFC, and BC was inserted in the esophagus. Controlled and assisted mechanical ventilation were applied with positive end-expiratory pressures of 5 and 15 cmH2O, and driving pressures of 10 and 20 cmH2O, in supine and lateral decubitus. Cardiogenic noise in BC tracings was much larger (up to 25% of total power of Pes signal) than in AFC and LFC (<3%). Lung and chest wall elastance, pressure-time product, inspiratory work of breathing, inspiratory change and end-expiratory value of transpulmonary pressure were estimated. The three catheters allowed detecting similar changes in these parameters between different ventilation settings. However, a non-negligible and significant bias between estimates from BC and those from AFC and LFC was observed in several instances. In anesthetized and mechanically ventilated pigs, the three catheters are equivalent when the aim is to detect changes in Pes and related parameters between different conditions, but possibly not when the absolute value of the estimated parameters is of paramount importance. Due to a better signal-to-noise ratio, and considering its practical advantages in terms of easier calibration and simpler acquisition setup, LFC may prove interesting for clinical use.

Mechanical Ventilation in Patients with the Acute Respiratory Distress Syndrome and Treated with Extracorporeal Membrane Oxygenation: Impact on Hospital and 30 Day Postdischarge Survival.

PubMed

Modrykamien, Ariel M; Hernandez, Omar O; Im, Yunhee; Walters, Ryan W; Schrader, Caleb L; Smith, Lauren E; Lima, Brian

2016-01-01

Mechanical ventilation support for acute respiratory distress syndrome (ARDS) patients involves the use of low tidal volumes and positive end-expiratory pressure. Nevertheless, the optimal ventilator strategy for ARDS patients undergoing extracorporeal membrane oxygenation (ECMO) therapy remains unknown. A retrospective analysis of a consecutive series of adult ARDS patients treated with V-V ECMO from October 2012 to May 2015 was performed. Mechanical ventilation data, as well as demographic and clinical data, were collected. We assessed the association between ventilator data and outcomes of interest. The primary outcome was hospital survival. Secondary outcome was 30 day survival posthospital discharge. Sixty-four ARDS patients were treated with ECMO. Univariate analysis showed that plateau pressure was independently associated with hospital survival. Tidal volume, positive end-expiratory pressure (PEEP), and plateau were independently associated with 30 day survival. Multivariate analysis, after controlling for covariates, revealed that a 1 unit increase in plateau pressure was associated with a 21% decrease in the odds of hospital survival (95% confidence interval [CI] = 6.39-33.42%, p = 0.007). In regards to 30 day survival postdischarge, a 1 unit increase in plateau pressure was associated with a 14.4% decrease in the odds of achieving the aforementioned outcome (95% CI = 1.75-25.4%, p = 0.027). Also, a 1 unit increase in PEEP was associated with a 36.2% decrease in the odds of 30 day survival (95% CI = 10.8-54.4%, p = 0.009). Among ARDS patients undergoing ECMO therapy, only plateau pressure is associated with hospital survival. Plateau pressure and PEEP are both associated with 30 day survival posthospital discharge.

Effects of Modes, Obesity, and Body Position on Non-invasive Positive Pressure Ventilation Success in the Intensive Care Unit: A Randomized Controlled Study.

PubMed

Türk, Murat; Aydoğdu, Müge; Gürsel, Gül

2018-01-01

Different outcomes and success rates of non-invasive positive pressure ventilation (NPPV) in patients with acute hypercapnic respiratory failure (AHRF) still pose a significant problem in intensive care units. Previous studies investigating different modes, body positioning, and obesity-associated hypoventilation in patients with chronic respiratory failure showed that these factors may affect ventilator mechanics to achieve a better minute ventilation. This study tried to compare pressure support (BiPAP-S) and average volume targeted pressure support (AVAPS-S) modes in patients with acute or acute-on-chronic hypercapnic respiratory failure. In addition, short-term effects of body position and obesity within both modes were analyzed. We conducted a randomized controlled study in a 7-bed intensive care unit. The course of blood gas analysis and differences in ventilation variables were compared between BiPAP-S (n=33) and AVAPS-S (n=29), and between semi-recumbent and lateral positions in both modes. No difference was found in the length of hospital stay and the course of PaCO2, pH, and HCO3 levels between the modes. There was a mean reduction of 5.7±4.1 mmHg in the PaCO2 levels in the AVAPS-S mode, and 2.7±2.3 mmHg in the BiPAP-S mode per session (p<0.05). Obesity didn't have any effect on the course of PaCO2 in both the modes. Body positioning had no notable effect in both modes. Although the decrease in the PaCO2 levels in the AVAPS-S mode per session was remarkably high, the course was similar in both modes. Furthermore, obesity and body positioning had no prominent effect on the PaCO2 response and ventilator mechanics. Post hoc power analysis showed that the sample size was not adequate to detect a significant difference between the modes.

Adaptive support ventilation: State of the art review

PubMed Central

Fernández, Jaime; Miguelena, Dayra; Mulett, Hernando; Godoy, Javier; Martinón-Torres, Federico

2013-01-01

Mechanical ventilation is one of the most commonly applied interventions in intensive care units. Despite its life-saving role, it can be a risky procedure for the patient if not applied appropriately. To decrease risks, new ventilator modes continue to be developed in an attempt to improve patient outcomes. Advances in ventilator modes include closed-loop systems that facilitate ventilator manipulation of variables based on measured respiratory parameters. Adaptive support ventilation (ASV) is a positive pressure mode of mechanical ventilation that is closed-loop controlled, and automatically adjust based on the patient's requirements. In order to deliver safe and appropriate patient care, clinicians need to achieve a thorough understanding of this mode, including its effects on underlying respiratory mechanics. This article will discuss ASV while emphasizing appropriate ventilator settings, their advantages and disadvantages, their particular effects on oxygenation and ventilation, and the monitoring priorities for clinicians. PMID:23833471

Regenerative Blower for EVA Suit Ventilation Fan

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Paul, Heather L.

2010-01-01

Portable life support systems in future space suits will include a ventilation subsystem driven by a dedicated fan. This ventilation fan must meet challenging requirements for pressure rise, flow rate, efficiency, size, safety, and reliability. This paper describes research and development that showed the feasibility of a regenerative blower that is uniquely suited to meet these requirements. We proved feasibility through component tests, blower tests, and design analysis. Based on the requirements for the Constellation Space Suit Element (CSSE) Portable Life Support System (PLSS) ventilation fan, we designed the critical elements of the blower. We measured the effects of key design parameters on blower performance using separate effects tests, and used the results of these tests to design a regenerative blower that will meet the ventilation fan requirements. We assembled a proof-of-concept blower and measured its performance at sub-atmospheric pressures that simulate a PLSS ventilation loop environment. Head/flow performance and maximum efficiency point data were used to specify the design and operating conditions for the ventilation fan. We identified materials for the blower that will enhance safety for operation in a lunar environment, and produced a solid model that illustrates the final design. The proof-of-concept blower produced the flow rate and pressure rise needed for the CSSE ventilation subsystem while running at 5400 rpm, consuming only 9 W of electric power using a non-optimized, commercial motor and controller and inefficient bearings. Scaling the test results to a complete design shows that a lightweight, compact, reliable, and low power regenerative blower can meet the performance requirements for future space suit life support systems.

Improved oxygenation 24 hours after transition to airway pressure release ventilation or high-frequency oscillatory ventilation accurately discriminates survival in immunocompromised pediatric patients with acute respiratory distress syndrome*.

PubMed

Yehya, Nadir; Topjian, Alexis A; Thomas, Neal J; Friess, Stuart H

2014-05-01

Children with an immunocompromised condition and requiring invasive mechanical ventilation have high risk of death. Such patients are commonly transitioned to rescue modes of nonconventional ventilation, including airway pressure release ventilation and high-frequency oscillatory ventilation, for acute respiratory distress syndrome refractory to conventional ventilation. Our aim was to describe our experience with airway pressure release ventilation and high-frequency oscillatory ventilation in children with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation and to identify factors associated with survival. Retrospective cohort study. Tertiary care, university-affiliated PICU. Sixty pediatric patients with an immunocompromised condition and acute respiratory distress syndrome refractory to conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation. None. Demographic data, ventilator settings, arterial blood gases, oxygenation index, and PaO(2)/FIO(2) were recorded before transition to either mode of nonconventional ventilation and at predetermined intervals after transition for up to 5 days. Mortality in the entire cohort was 63% and did not differ between patients transitioned to airway pressure release ventilation and high-frequency oscillatory ventilation. For both airway pressure release ventilation and high-frequency oscillatory ventilation, improvements in oxygenation index and PaO(2)/FIO(2) at 24 hours expressed as a fraction of pretransition values (oxygenation index(24)/oxygenation index(pre) and PaO(2)/FIO(224)/PaO(2)/FIO(2pre)) reliably discriminated nonsurvivors from survivors, with receiver operating characteristic areas under the curves between 0.89 and 0.95 (p for all curves < 0.001). Sensitivity-specificity analysis suggested that less than 15% reduction in oxygenation index (90% sensitive, 75% specific) or less than 90% increase in PaO(2)/FIO(2) (80% sensitive, 94% specific) 24 hours after transition to airway pressure release ventilation were the optimal cutoffs to identify nonsurvivors. The comparable values 24 hours after transition to high-frequency oscillatory ventilation were less than 5% reduction in oxygenation index (100% sensitive, 83% specific) or less than 80% increase in PaO(2)/FIO(2) (91% sensitive, 89% specific) to identify nonsurvivors. In this single-center retrospective study of pediatric patients with an immunocompromised condition and acute respiratory distress syndrome failing conventional ventilation transitioned to either airway pressure release ventilation or high-frequency oscillatory ventilation, improved oxygenation at 24 hours expressed as PaO(2)/FIO(224)/PaO(2)/FIO(2pre) or oxygenation index(24)/oxygenation indexpre reliably discriminates nonsurvivors from survivors. These findings should be prospectively verified.

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.

Adaptive Servo-Ventilation for Central Sleep Apnea in Systolic Heart Failure.

PubMed

Cowie, Martin R; Woehrle, Holger; Wegscheider, Karl; Angermann, Christiane; d'Ortho, Marie-Pia; Erdmann, Erland; Levy, Patrick; Simonds, Anita K; Somers, Virend K; Zannad, Faiez; Teschler, Helmut

2015-09-17

Central sleep apnea is associated with poor prognosis and death in patients with heart failure. Adaptive servo-ventilation is a therapy that uses a noninvasive ventilator to treat central sleep apnea by delivering servo-controlled inspiratory pressure support on top of expiratory positive airway pressure. We investigated the effects of adaptive servo-ventilation in patients who had heart failure with reduced ejection fraction and predominantly central sleep apnea. We randomly assigned 1325 patients with a left ventricular ejection fraction of 45% or less, an apnea-hypopnea index (AHI) of 15 or more events (occurrences of apnea or hypopnea) per hour, and a predominance of central events to receive guideline-based medical treatment with adaptive servo-ventilation or guideline-based medical treatment alone (control). The primary end point in the time-to-event analysis was the first event of death from any cause, lifesaving cardiovascular intervention (cardiac transplantation, implantation of a ventricular assist device, resuscitation after sudden cardiac arrest, or appropriate lifesaving shock), or unplanned hospitalization for worsening heart failure. In the adaptive servo-ventilation group, the mean AHI at 12 months was 6.6 events per hour. The incidence of the primary end point did not differ significantly between the adaptive servo-ventilation group and the control group (54.1% and 50.8%, respectively; hazard ratio, 1.13; 95% confidence interval [CI], 0.97 to 1.31; P=0.10). All-cause mortality and cardiovascular mortality were significantly higher in the adaptive servo-ventilation group than in the control group (hazard ratio for death from any cause, 1.28; 95% CI, 1.06 to 1.55; P=0.01; and hazard ratio for cardiovascular death, 1.34; 95% CI, 1.09 to 1.65; P=0.006). Adaptive servo-ventilation had no significant effect on the primary end point in patients who had heart failure with reduced ejection fraction and predominantly central sleep apnea, but all-cause and cardiovascular mortality were both increased with this therapy. (Funded by ResMed and others; SERVE-HF ClinicalTrials.gov number, NCT00733343.).

[Face protective patches do not reduce facial pressure ulcers in a simulated model of non-invasive ventilation].

PubMed

Riquelme M, Hugo; Wood V, David; Martínez F, Santiago; Carmona M, Fernando; Peña V, Axel; Wegner A, Adriana

2017-06-01

Noninvasive ventilation (NIV) frequently involves the development of facial pressure ulcers (FPU). Its prevention considers the empirical use of protective patches between skin and mask, in order to reduce the pressure exerted by it. To evaluate the effect of protective patches on the pressure exerted by the facial mask, and its impact on the programmed ventilatory parameters. Bilevel NIV simulated model using full face mask in phantom with a physiological airway (ALS PRO +) in supine position. Forehead, chin and cheekbones pressure were measured using 3 types of standard protective patches versus a control group using pressure sensors (Interlinks Electronics®). The values obtained with the protective patches-mask model were evaluated in the programmed variables maximum inspiratory flow (MIF)), expired tidal volume (Vte) and positive inspiratory pressure (IPAP), with Trilogy 100 ventilator, Respironics®. The programming and recording of the variables was carried out in 8 opportunities in each group by independent operators. There was no decrease in facial pressure with any of the protective patches compared to the control group. Moltopren increased facial pressure at all support points (p < 0.001), increased leakage, it decreased MIF, Vte and IPAP (p < 0.001). Hydrocolloid patches increased facial pressure only in the left cheekbone, increased leakage and decreased MIF. Polyurethane patches did not produce changes in facial pressure or ventilatory variables. The use of protective patches of moltopren, hydrocolloid and polyurethane transparent did not contribute to the decrease of the facial pressure. A deleterious effect of the moltopren and hydrocolloid patches was observed on the administration of ventilatory variables, concluding that the non-use of the protective patches allowed a better administration of the programmed parameters.

A dual closed-loop control system for mechanical ventilation.

PubMed

Tehrani, Fleur; Rogers, Mark; Lo, Takkin; Malinowski, Thomas; Afuwape, Samuel; Lum, Michael; Grundl, Brett; Terry, Michael

2004-04-01

Closed-loop mechanical ventilation has the potential to provide more effective ventilatory support to patients with less complexity than conventional ventilation. The purpose of this study was to investigate the effectiveness of an automatic technique for mechanical ventilation. Two closed-loop control systems for mechanical ventilation are combined in this study. In one of the control systems several physiological data are used to automatically adjust the frequency and tidal volume of breaths of a patient. This method, which is patented under US Patent number 4986268, uses the criterion of minimal respiratory work rate to provide the patient with a natural pattern of breathing. The inputs to the system include data representing CO2 and O2 levels of the patient as well as respiratory compliance and airway resistance. The I:E ratio is adjusted on the basis of the respiratory time constant to allow for effective emptying of the lungs in expiration and to avoid intrinsic positive end expiratory pressure (PEEP). This system is combined with another closed-loop control system for automatic adjustment of the inspired fraction of oxygen of the patient. This controller uses the feedback of arterial oxygen saturation of the patient and combines a rapid stepwise control procedure with a proportional-integral-derivative (PID) control algorithm to automatically adjust the oxygen concentration in the patient's inspired gas. The dual closed-loop control system has been examined by using mechanical lung studies, computer simulations and animal experiments. In the mechanical lung studies, the ventilation controller adjusted the breathing frequency and tidal volume in a clinically appropriate manner in response to changes in respiratory mechanics. The results of computer simulations and animal studies under induced disturbances showed that blood gases were returned to the normal physiologic range in less than 25 s by the control system. In the animal experiments understeady-state conditions, the maximum standard deviations of arterial oxygen saturation and the end-tidal partial pressure of CO2 were +/- 1.76% and +/- 1.78 mmHg, respectively. The controller maintained the arterial blood gases within normal limits under steady-state conditions and the transient response of the system was robust under various disturbances. The results of the study have showed that the proposed dual closed-loop technique has effectively controlled mechanical ventilation under different test conditions.

Flow analysis of airborne particles in a hospital operating room

NASA Astrophysics Data System (ADS)

Faeghi, Shiva; Lennerts, Kunibert

2016-06-01

Preventing airborne infections during a surgery has been always an important issue to deliver effective and high quality medical care to the patient. One of the important sources of infection is particles that are distributed through airborne routes. Factors influencing infection rates caused by airborne particles, among others, are efficient ventilation and the arrangement of surgical facilities inside the operating room. The paper studies the ventilation airflow pattern in an operating room in a hospital located in Tehran, Iran, and seeks to find the efficient configurations with respect to the ventilation system and layout of facilities. This study uses computational fluid dynamics (CFD) and investigates the effects of different inflow velocities for inlets, two pressurization scenarios (equal and excess pressure) and two arrangements of surgical facilities in room while the door is completely open. The results show that system does not perform adequately when the door is open in the operating room under the current conditions, and excess pressure adjustments should be employed to achieve efficient results. The findings of this research can be discussed in the context of design and controlling of the ventilation facilities of operating rooms.

Does Bilevel Positive Airway Pressure Improve Outcome of Acute Respiratory Failure after Open-heart Surgery?

PubMed Central

Elgebaly, Ahmed Said

2017-01-01

Background: Respiratory failure is of concern in the postoperative period after cardiac surgeries. Invasive ventilation (intermittent positive pressure ventilation [IPPV]) carries the risks and complications of intubation and mechanical ventilation (MV). Aims: Noninvasive positive pressure ventilation (NIPPV) is an alternative method and as effective as IPPV in treating insufficiency of respiration with less complications and minimal effects on respiratory and hemodynamic parameters next to open-heart surgery. Design: This is a prospective, randomized and controlled study. Materials and Methods: Forty-four patients scheduled for cardiac surgery were divided into two equal groups: Group I (IPPV) and Group II (NIPPV). Heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), oxygen saturation (SpO2), arterial blood gas, weaning time, reintubation, tracheotomy rate, MV time, postoperative hospital stay, and ventilator-associated pneumonia during the period of hospital stay were recorded. Results: There was statistically significant difference in HR between groups with higher in Group I at 30 and 60 min and at 12 and 24 h. According to MAP, it started to increase significantly at hypoxemia, 15 min, 30 min, 4 h, 12 h, and at 24 h which was higher in Group I also. RR, PaO2, and PaCO2 showed significant higher in Group II at 15, 30, and 60 min and 4 h. According to pH, there was a significant difference between groups at 15, 30, and 60 min and at 4, 12, and 24 h postoperatively. SpO2 showed higher significant values in Group I at 15 and 30 min and at 12 h postoperatively. Duration of postoperative supportive ventilation was higher in Group I than that of Group II with statistically significant difference. Complications were statistically insignificant between Group I and Group II. Conclusion: Our study showed superiority of invasive over noninvasive mode of ventilator support. However, NIPPV (bilevel positive airway pressure) was proved to be a safe method. PMID:28994676

[Anesthesia ventilators].

PubMed

Otteni, J C; Beydon, L; Cazalaà, J B; Feiss, P; Nivoche, Y

1997-01-01

To review anaesthesia ventilators in current use in France by categories of ventilators. References were obtained from computerized bibliographic search. (Medline), recent review articles, the library of the service and personal files. Anaesthesia ventilators can be allocated into three groups, depending on whether they readminister expired gases or not or allow both modalities. Contemporary ventilators provide either constant volume ventilation, or constant pressure ventilation, with or without a pressure plateau. Ventilators readministering expired gases after CO2 absorption, or closed circuit ventilators, are either of a double- or a single-circuit design. Double-circuit ventilators, or pneumatical bag or bellows squeezers, or bag-in-bottle or bellows-in-bottle (or box) ventilators, consist of a primary, or driving circuit (bottle or box) and a secondary or patient circuit (including a bag or a bellows or membrane chambers). Bellows-in-bottle ventilators have either standing bellows ascending at expiration, or hanging bellows, descending at expiration. Ascending bellows require a positive pressure of about 2 cmH2O throughout exhalation to allow the bellows to refill. The expired gas volume is a valuable indicator for leak and disconnection. Descending bellows generate a slight negative pressure during exhalation. In case of leak or disconnection they aspirate ambient air and cannot act therefore as an indicator for integrity of the circuit and the patient connection. Closed circuit ventilators with a single-circuit (patient circuit) include a insufflating device consisting either in a bellows or a cylinder with a piston, operated by a electric or pneumatic motor. As the hanging bellows of the double circuit ventilators, they generate a slight negative pressure during exhalation and aspirate ambient air in case of leak or disconnection. Ventilators not designed for the readministration of expired gases, or open circuit ventilators, are generally stand-alone mechanical ventilators modified to allow the administration of inhalational anaesthetic agents.

Comparison of the effects of moderate and severe hypercapnic acidosis on ventilation-induced lung injury.

PubMed

Yang, Wanchao; Yue, Ziyong; Cui, Xiaoguang; Guo, Yueping; Zhang, Lili; Zhou, Huacheng; Li, Wenzhi

2015-04-30

We have proved that hypercapnic acidosis (a PaCO2 of 80-100 mmHg) protects against ventilator-induced lung injury in rats. However, there remains uncertainty regarding the appropriate target PaCO2 or if greater CO2 "doses" (PaCO2 > 100 mmHg) demonstrate this effect. We wished to determine whether severe acute hypercapnic acidosis can reduce stretch-induced injury, as well as the role of nuclear factor-κB (NF-κB) in the effects of acute hypercapnic acidosis. Fifty-four rats were ventilated for 4 hours with a pressure-controlled ventilation mode set at a peak inspiratory pressure (PIP) of 30 cmH2O. A gas mixture of carbon dioxide with oxygen (FiCO2 = 4-5%, FiCO2 = 11-12% or FiCO2 = 16-17%; FiO2 = 0.7; balance N2) was immediately administered to maintain the target PaCO2 in the NC (a PaCO2 of 35-45 mmHg), MHA (a PaCO2 of 80-100 mmHg) and SHA (a PaCO2 of 130-150 mmHg) groups. Nine normal or non-ventilated rats served as controls. The hemodynamics, gas exchange and inflammatory parameters were measured. The role of NF-κB pathway in hypercapnic acidosis-mediated protection from high-pressure stretch injury was then determined. In the NC group, high-pressure ventilation resulted in a decrease in PaO2/FiO2 from 415.6 (37.1) mmHg to 179.1 (23.5) mmHg (p < 0.001), but improved by MHA (379.9 ± 34.5 mmHg) and SHA (298.6 ± 35.3 mmHg). The lung injury score in the SHA group (7.8 ± 1.6) was lower than the NC group (11.8 ± 2.3, P < 0.05) but was higher than the MHA group (4.4 ± 1.3, P < 0.05). Compared with the NC group, after 4 h of high pressure ventilation, the MHA and SHA groups had decreases in MPO activity of 67% and 33%, respectively, and also declined the levels of TNF-α (58% versus 72%) and MIP-2 (76% versus 60%) in the BALF. Additionally, both hypercapnic acidosis groups reduced stretch-induced NF-κB activation (p < 0.05) and significantly decreased lung ICAM-1 expression (p < 0.05). Moderate hypercapnic acidosis (PaCO2 maintained at 80-100 mmHg) has a greater protective effect on high-pressure ventilation-induced inflammatory injury. The potential mechanisms may involve alterations in NF-κB activity.

Use of a single ventilator to support 4 patients: laboratory evaluation of a limited concept.

PubMed

Branson, Richard D; Blakeman, Thomas C; Robinson, Bryce Rh; Johannigman, Jay A

2012-03-01

A mass-casualty respiratory failure event where patients exceed available ventilators has spurred several proposed solutions. One proposal is use of a single ventilator to support 4 patients. A ventilator was modified to allow attachment of 4 circuits. Each circuit was connected to one chamber of 2 dual-chambered, test lungs. The ventilator was set at a tidal volume (V(T)) of 2.0 L, respiratory frequency of 10 breaths/min, and PEEP of 5 cm H(2)O. Tests were repeated with pressure targeted breaths at 15 cm H(2)O. Airway pressure, volume, and flow were measured at each chamber. The test lungs were set to simulate 4 patients using combinations of resistance (R) and compliance (C). These included equivalent C and R, constant R and variable C, constant C and variable R, and variable C and variable R. When R and C were equivalent the V(T) distributed to each chamber of the test lung was similar during both volume (range 428-442 mL) and pressure (range 528-544 mL) breaths. Changing C while R was constant resulted in large variations in delivered V(T) (volume range 257-621 mL, pressure range 320-762 mL). Changing R while C was constant resulted in a smaller variation in V(T) (volume range 418-460 mL, pressure range 502-554 mL) compared to only C changes. When R and C were both varied, the range of delivered V(T) in both volume (336-517 mL) and pressure (417-676 mL) breaths was greater, compared to only R changes. Using a single ventilator to support 4 patients is an attractive concept; however, the V(T) cannot be controlled for each subject and V(T) disparity is proportional to the variability in compliance. Along with other practical limitations, these findings cannot support the use of this concept for mass-casualty respiratory failure.

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.

76 FR 16446 - Delphi Corporation Electronics And Safety Division Including On-Site Leased Workers From Acro...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-23

...: Heating, ventilating, air-conditioning systems (HVAC), amplifiers, mainboards, gas control modules, hybrid airmeter electronics, hybrid ignition electronics, pressure sensors, transmission control modules, crash...

Ventilatory changes during the use of heat and moisture exchangers in patients submitted to mechanical ventilation with support pressure and adjustments in ventilation parameters to compensate for these possible changes: a self-controlled intervention study in humans.

PubMed

Lucato, Jeanette Janaina Jaber; Cunha, Thiago Marraccini Nogueira da; Reis, Aline Mela Dos; Picanço, Patricia Salerno de Almeida; Barbosa, Renata Cléia Claudino; Liberali, Joyce; Righetti, Renato Fraga

2017-01-01

To evaluate the possible changes in tidal volume, minute volume and respiratory rate caused by the use of a heat and moisture exchanger in patients receiving pressure support mechanical ventilation and to quantify the variation in pressure support required to compensate for the effect caused by the heat and moisture exchanger. Patients under invasive mechanical ventilation in pressure support mode were evaluated using heated humidifiers and heat and moisture exchangers. If the volume found using the heat and moisture exchangers was lower than that found with the heated humidifier, an increase in pressure support was initiated during the use of the heat and moisture exchanger until a pressure support value was obtained that enabled the patient to generate a value close to the initial tidal volume obtained with the heated humidifier. The analysis was performed by means of the paired t test, and incremental values were expressed as percentages of increase required. A total of 26 patients were evaluated. The use of heat and moisture exchangers increased the respiratory rate and reduced the tidal and minute volumes compared with the use of the heated humidifier. Patients required a 38.13% increase in pressure support to maintain previous volumes when using the heat and moisture exchanger. The heat and moisture exchanger changed the tidal and minute volumes and respiratory rate parameters. Pressure support was increased to compensate for these changes.

Ventilatory changes during the use of heat and moisture exchangers in patients submitted to mechanical ventilation with support pressure and adjustments in ventilation parameters to compensate for these possible changes: a self-controlled intervention study in humans

PubMed Central

Lucato, Jeanette Janaina Jaber; da Cunha, Thiago Marraccini Nogueira; dos Reis, Aline Mela; Picanço, Patricia Salerno de Almeida; Barbosa, Renata Cléia Claudino; Liberali, Joyce; Righetti, Renato Fraga

2017-01-01

Objective To evaluate the possible changes in tidal volume, minute volume and respiratory rate caused by the use of a heat and moisture exchanger in patients receiving pressure support mechanical ventilation and to quantify the variation in pressure support required to compensate for the effect caused by the heat and moisture exchanger. Methods Patients under invasive mechanical ventilation in pressure support mode were evaluated using heated humidifiers and heat and moisture exchangers. If the volume found using the heat and moisture exchangers was lower than that found with the heated humidifier, an increase in pressure support was initiated during the use of the heat and moisture exchanger until a pressure support value was obtained that enabled the patient to generate a value close to the initial tidal volume obtained with the heated humidifier. The analysis was performed by means of the paired t test, and incremental values were expressed as percentages of increase required. Results A total of 26 patients were evaluated. The use of heat and moisture exchangers increased the respiratory rate and reduced the tidal and minute volumes compared with the use of the heated humidifier. Patients required a 38.13% increase in pressure support to maintain previous volumes when using the heat and moisture exchanger. Conclusion The heat and moisture exchanger changed the tidal and minute volumes and respiratory rate parameters. Pressure support was increased to compensate for these changes. PMID:28977257

A Case of Shunting Postoperative Patent Foramen Ovale Under Mechanical Ventilation Controlled by Different Ventilator Settings.

PubMed

Pragliola, Claudio; Di Michele, Sara; Galzerano, Domenico

2017-06-07

A 56-year old male with ischemic heart disease and an unremarkable preoperative echocardiogram underwent surgical coronary revascularization. An intraoperative post pump trans-esophageal echocardiogram (TOE) performed while the patient was being ventilated at a positive end expiratory pressure (PEEP) of 8 cm H 2 O demonstrated a right to left interatrial shunt across a patent foramen ovale (PFO). Whereas oxygen saturation was normal, a reduction of the PEEP to 3 cm H 2 O led to the complete resolution of the shunt with no change in arterial blood gases. Attempts to increase the PEEP level above 3 mmHg resulted in recurrence of the interatrial shunt. The remaining of the TEE was unremarkable. Mechanical ventilation, particularly with PEEP, causes an increase in intrathoracic pressure. The resulting rise in right atrial pressure, mostly during inspiration, may unveil and pop open an unrecognized PFO, thus provoking a right to left shunt across a seemingly intact interatrial septum. This phenomenon increases the risk of paradoxical embolism and can lead to hypoxemia. The immediate management would be to adjust the ventilatory settings to a lower PEEP level. A routine search for a PFO should be performed in ventilated patients who undergo a TEE.

Low tidal volume mechanical ventilation against no ventilation during cardiopulmonary bypass heart surgery (MECANO): study protocol for a randomized controlled trial.

PubMed

Nguyen, Lee S; Merzoug, Messaouda; Estagnasie, Philippe; Brusset, Alain; Law Koune, Jean-Dominique; Aubert, Stephane; Waldmann, Thierry; Grinda, Jean-Michel; Gibert, Hadrien; Squara, Pierre

2017-12-02

Postoperative pulmonary complications are a leading cause of morbidity and mortality after cardiac surgery. There are no recommendations on mechanical ventilation associated with cardiopulmonary bypass (CPB) during surgery and anesthesiologists perform either no ventilation (noV) at all during CPB or maintain low tidal volume (LTV) ventilation. Indirect evidence points towards better pulmonary outcomes when LTV is performed but no large-scale prospective trial has yet been published in cardiac surgery. The MECANO trial is a single-center, double-blind, randomized, controlled trial comparing two mechanical ventilation strategies, noV and LTV, during cardiac surgery with CPB. In total, 1500 patients are expected to be included, without any restrictions. They will be randomized between noV and LTV on a 1:1 ratio. The noV group will receive no ventilation during CPB. The LTV group will receive 5 breaths/minute with a tidal volume of 3 mL/kg and positive end-expiratory pressure of 5 cmH2O. The primary endpoint will be a composite of all-cause mortality, early respiratory failure defined as a ratio of partial pressure of oxygen/fraction of inspired oxygen <200 mmHg at 1 hour after arrival in the ICU, heavy oxygenation support (defined as a patient requiring either non-invasive ventilation, mechanical ventilation or high-flow oxygen) at 2 days after arrival in the ICU or ventilator-acquired pneumonia defined by the Center of Disease Control. Lung recruitment maneuvers will be performed in the noV and LTV groups at the end of surgery and at arrival in ICU with an insufflation at +30 cmH20 for 5 seconds. Secondary endpoints are those composing the primary endpoint with the addition of pneumothorax, CPB duration, quantity of postoperative bleeding, red blood cell transfusions, revision surgery requirements, length of stay in the ICU and in the hospital and total hospitalization costs. Patients will be followed until hospital discharge. The MECANO trial is the first of its kind to compare in a double-blind design, a no-ventilation to a low-tidal volume strategy for mechanical ventilation during cardiac surgery with CPB, with a primary composite outcome including death, respiratory failure and postoperative pneumonia. ClinicalTrials.gov, NCT03098524 . Registered on 27 February 2017.

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.

[Intraoperative monitoring in artificial respiration of premature and newborn infants. I. Monitoring of respiratory parameters and alveolar ventilation].

PubMed

Lenz, G; Heipertz, W; Leidig, E; Madee, S

1986-06-01

Monitoring of ventilation serves to ensure adequate alveolar ventilation and arterial oxygenation, and to avoid pulmonary damage due to mechanical ventilation. Basic clinical monitoring, i.e., inspection, auscultation (including precordial or oesophageal stethoscope) and monitoring of heart rate and blood pressure, is mandatory. Mechanical ventilation is monitored by ventilation pressures (peak pressure, plateau pressure and endexpiratory pressure), ventilation volumes (measured at the in/expiratory valve of the respirator and by hot-wire anemometry at the tube connector), ventilation rate, and inspiratory oxygen concentration (FiO2). Alveolar ventilation should be continuously and indirectly recorded by capnometry (pECO2) and by measurement of transcutaneous pCO2 (tcpCO2), whereas oxygenation is determined via measurement of transcutaneous pO2 (tcpO2). Invasive monitoring of gas exchange is essential in prolonged or intrathoracic interventions as well as in neonates with cardiopulmonary problems. paCO2 may be estimated by capillary or venous blood gas analysis; arterial blood gas analysis is required for exact determination of paCO2 as well as arteriocutaneous pCO2 (atcDCO2) and arterio-end-expiratory (aEDCO2) gradients.

Gadolinium prevents high airway pressure-induced permeability increases in isolated rat lungs.

PubMed

Parker, J C; Ivey, C L; Tucker, J A

1998-04-01

To determine the initial signaling event in the vascular permeability increase after high airway pressure injury, we compared groups of lungs ventilated at different peak inflation pressures (PIPs) with (gadolinium group) and without (control group) infusion of 20 microM gadolinium chloride, an inhibitor of endothelial stretch-activated cation channels. Microvascular permeability was assessed by using the capillary filtration coefficient (Kfc), a measure of capillary hydraulic conductivity. Kfc was measured after ventilation for 30-min periods with 7, 20, and 30 cmH2O PIP with 3 cmH2O positive end-expiratory pressure and with 35 cmH2O PIP with 8 cmH2O positive end-expiratory pressure. In control lungs, Kfc increased significantly to 1.8 and 3.7 times baseline after 30 and 35 cmH2O PIP, respectively. In the gadolinium group, Kfc was unchanged from baseline (0.060 +/- 0.010 ml . min-1 . cmH2O-1 . 100 g-1) after any PIP ventilation period. Pulmonary vascular resistance increased significantly from baseline in both groups before the last Kfc measurement but was not different between groups. These results suggest that microvascular permeability is actively modulated by a cellular response to mechanical injury and that stretch-activated cation channels may initiate this response through increases in intracellular calcium concentration.

Cerebral hypoxia

MedlinePlus

... support is most important. Treatment involves: Breathing assistance (mechanical ventilation) and oxygen Controlling the heart rate and rhythm Fluids, blood products, or medicines to raise blood pressure ...

Inspiratory capacity at inflation hold in ventilated newborns: a surrogate measure for static compliance of the respiratory system.

PubMed

Hentschel, Roland; Semar, Nicole; Guttmann, Josef

2012-09-01

To study appropriateness of respiratory system compliance calculation using an inflation hold and compare it with ventilator readouts of pressure and tidal volume as well as with measurement of compliance of the respiratory system with the single-breath-single-occlusion technique gained with a standard lung function measurement. Prospective clinical trial. Level III neonatal unit of a university hospital. Sixty-seven newborns, born prematurely or at term, ventilated for a variety of pathologic conditions. A standardized sigh maneuver with a predefined peak inspiratory pressure of 30 cm H2O, termed inspiratory capacity at inflation hold, was applied. Using tidal volume, exhaled from inspiratory pause down to ambient pressure, as displayed by the ventilator, and predefined peak inspiratory pressure, compliance at inspiratory capacity at inflation hold conditions could be calculated as well as ratio of tidal volume and ventilator pressure using tidal volume and differential pressure at baseline ventilator settings: peak inspiratory pressure minus positive end-expiratory pressure. For the whole cohort, the equation for the regression between tidal volume at inspiratory capacity at inflation hold and compliance of the respiratory system was: compliance of the respiratory system = 0.052 * tidal volume at inspiratory capacity at inflation hold - 0.113, and compliance at inspiratory capacity at inflation hold conditions was closely related to the standard lung function measurement method of compliance of the respiratory system (R = 0.958). In contrast, ratio of tidal volume and ventilator pressure per kilogram calculated from the ventilator readouts and displayed against compliance of the respiratory system per kilogram yielded a broad scatter throughout the whole range of compliance; both were only weakly correlated (R = 0.309) and also the regression line was significantly different from the line of identity (p < .05). Peak inspiratory pressure at study entry did not affect the correlation between compliance at inspiratory capacity at inflation hold conditions and compliance of the respiratory system. After a standard sigh maneuver, inspiratory capacity at inflation hold and the derived quantity compliance at inspiratory capacity at inflation hold conditions can be regarded as a valid, accurate, and reliable surrogate measure for standard compliance of the respiratory system in contrast to ratio of tidal volume and ventilator pressure calculated from the ventilator readouts during ongoing mechanical ventilation at respective ventilator settings.

[Pressure support ventilation and proportional assist ventilation during weaning from mechanical ventilation].

PubMed

Aguirre-Bermeo, H; Bottiroli, M; Italiano, S; Roche-Campo, F; Santos, J A; Alonso, M; Mancebo, J

2014-01-01

To compare tolerance, duration of mechanical ventilation (MV) and clinical outcomes during weaning from MV in patients subjected to either pressure support ventilation (PSV) or proportional assist ventilation (PAV). A prospective, observational study was carried out. Intensive Care Unit. A total of 40 consecutive subjects were allocated to either the PSV or the PAV group until each group contained 20 patients. Patients were included in the study when they met the criteria to begin weaning and the attending physician decided to initiate the weaning process. The physician selected the modality and set the ventilatory parameters. None. Demographic data, respiratory mechanics, ventilatory parameters, duration of MV, and clinical outcomes (reintubation, tracheostomy, mortality). Baseline characteristics were similar in both groups. No significant differences were observed between the PSV and PAV groups in terms of the total duration of MV (10 [5-18] vs. 9 [7-19] days; P=.85), reintubation (5 [31%] vs. 3 [19%]; P=.69), or mortality (4 [20%] vs. 5 [25%] deaths; P=1). Eight patients (40%) in the PSV group and 6 patients (30%) in the PAV group (P=.74) required a return to volume assist-control ventilation due to clinical deterioration. Tolerance, duration of MV and clinical outcomes during weaning from mechanical ventilation were similar in PSV and PAV. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

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

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.

Anesthesia for thoracic surgery: A survey of middle eastern practice

PubMed Central

Eldawlatly, Abdelazeem; Turkistani, Ahmed; Shelley, Ben; El-Tahan, Mohamed; Macfie, Alistair; Kinsella, John

2012-01-01

Purpose: The main objective of this survey is to describe the current practice of thoracic anesthesia in the Middle Eastern (ME) region. Methods: A prospective online survey. An invitation to participate was e-mailed to all members of the ME thoracic-anaesthesia group. A total of 58 members participated in the survey from 19 institutions in the Middle East. Questions concerned ventilation strategies during one-lung ventilation (OLV), anesthesia regimen, mode of postoperative analgesia, use of lung isolation techniques, and use of i.v. fluids. Results: Volume-controlled ventilation was favored over pressure-controlled ventilation (62% vs 38% of respondents, P<0.05); 43% report the routine use of positive end-expiratory pressure. One hundred percent of respondents report using double-lumen tube (DLT) as a first choice airway to establish OLV. Nearly a third of respondents, 31.1%, report never using bronchial blocker (BB) in their thoracic anesthesia practice. Failure to pass a DLT and difficult airway are the most commonly cited indications for BB use. Regarding postoperative analgesia, the majority 61.8% favor thoracic epidural analgesia over other techniques (P<0.05). Conclusions: Our survey provides a contemporary snapshot of the ME thoracic anesthetic practice. PMID:23162388

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.

Performance of Leak Compensation in All-Age ICU Ventilators During Volume-Targeted Neonatal Ventilation: A Lung Model Study.

PubMed

Itagaki, Taiga; Bennett, Desmond J; Chenelle, Christopher T; Fisher, Daniel F; Kacmarek, Robert M

2017-01-01

Volume-targeted ventilation is increasingly used in low birthweight infants because of the potential for reducing volutrauma and avoiding hypocapnea. However, it is not known what level of air leak is acceptable during neonatal volume-targeted ventilation when leak compensation is activated concurrently. Four ICU ventilators (Servo-i, PB980, V500, and Avea) were compared in available invasive volume-targeted ventilation modes (pressure control continuous spontaneous ventilation [PC-CSV] and pressure control continuous mandatory ventilation [PC-CMV]). The Servo-i and PB980 were tested with (+) and without (-) their proximal flow sensor. The V500 and Avea were tested with their proximal flow sensor as indicated by their manufacturers. An ASL 5000 lung model was used to simulate 4 neonatal scenarios (body weight 0.5, 1, 2, and 4 kg). The ASL 5000 was ventilated via an endotracheal tube with 3 different leaks. Two minutes of data were collected after each change in leak level, and the asynchrony index was calculated. Tidal volume (V T ) before and after the change in leak was assessed. The differences in delivered V T between before and after the change in leak were within ±5% in all scenarios with the PB980 (-/+) and V500. With the Servo-i (-/+), baseline V T was ≥10% greater than set V T during PC-CSV, and delivered V T markedly changed with leak. The Avea demonstrated persistent high V T in all leak scenarios. Across all ventilators, the median asynchrony index was 1% (interquartile range 0-27%) in PC-CSV and 1.8% (0-45%) in PC-CMV. The median asynchrony index was significantly higher in the Servo-i (-/+) than in the PB980 (-/+) and V500 in 1 and 2 kg scenarios during PC-CSV and PC-CMV. The PB980 and V500 were the only ventilators to acclimate to all leak scenarios and achieve targeted V T . Further clinical investigation is needed to validate the use of leak compensation during neonatal volume-targeted ventilation. Copyright © 2017 by Daedalus Enterprises.

Adaptive servo ventilation for central sleep apnoea in heart failure: SERVE-HF on-treatment analysis.

PubMed

Woehrle, Holger; Cowie, Martin R; Eulenburg, Christine; Suling, Anna; Angermann, Christiane; d'Ortho, Marie-Pia; Erdmann, Erland; Levy, Patrick; Simonds, Anita K; Somers, Virend K; Zannad, Faiez; Teschler, Helmut; Wegscheider, Karl

2017-08-01

This on-treatment analysis was conducted to facilitate understanding of mechanisms underlying the increased risk of all-cause and cardiovascular mortality in heart failure patients with reduced ejection fraction and predominant central sleep apnoea randomised to adaptive servo ventilation versus the control group in the SERVE-HF trial.Time-dependent on-treatment analyses were conducted (unadjusted and adjusted for predictive covariates). A comprehensive, time-dependent model was developed to correct for asymmetric selection effects (to minimise bias).The comprehensive model showed increased cardiovascular death hazard ratios during adaptive servo ventilation usage periods, slightly lower than those in the SERVE-HF intention-to-treat analysis. Self-selection bias was evident. Patients randomised to adaptive servo ventilation who crossed over to the control group were at higher risk of cardiovascular death than controls, while control patients with crossover to adaptive servo ventilation showed a trend towards lower risk of cardiovascular death than patients randomised to adaptive servo ventilation. Cardiovascular risk did not increase as nightly adaptive servo ventilation usage increased.On-treatment analysis showed similar results to the SERVE-HF intention-to-treat analysis, with an increased risk of cardiovascular death in heart failure with reduced ejection fraction patients with predominant central sleep apnoea treated with adaptive servo ventilation. Bias is inevitable and needs to be taken into account in any kind of on-treatment analysis in positive airway pressure studies. Copyright ©ERS 2017.

Occupational exposure to nitrous oxide - the role of scavenging and ventilation systems in reducing the exposure level in operating rooms.

PubMed

Krajewski, Wojciech; Kucharska, Malgorzata; Wesolowski, Wiktor; Stetkiewicz, Jan; Wronska-Nofer, Teresa

2007-03-01

The aim of this study was to assess the level of occupational exposure to nitrous oxide (N(2)O) in operating rooms (ORs), as related to different ventilation and scavenging systems used to remove waste anaesthetic gases from the work environment. The monitoring of N(2)O in the air covered 35 ORs in 10 hospitals equipped with different systems for ventilation and anaesthetic scavenging. The examined systems included: natural ventilation with supplementary fresh air provided by a pressure ventilation system (up to 6 air changes/h); pressure and exhaust ventilation systems equipped with ventilation units supplying fresh air to and discharging contaminated air outside the working area (more than 10 air changes/h); complete air-conditioning system with laminar air flow (more than 15 air changes/h). The measurements were carried out during surgical procedures (general anaesthesia induced intravenously and maintained with inhaled N(2)O and sevofluran delivered through cuffed endotracheal tubes) with connected or disconnected air scavenging. Air was collected from the breathing zone of operating personnel continuously through the whole time of anaesthesia to Tedlar((R)) bags, and N(2)O concentrations in air samples were analyzed by adsorption gas chromatography/mass spectrometry. N(2)O levels in excess of the occupational exposure limit (OEL) value of 180mg/m(3) were registered in all ORs equipped with ventilation systems alone. The OEL value was exceeded several times in rooms with natural ventilation plus supplementary pressure ventilations and twice or less in those with pressure/exhaust ventilation systems or air conditioning. N(2)O levels below or within the OEL value were observed in rooms where the system of air conditioning or pressure/exhaust ventilation was combined with scavenging systems. Systems combining natural/pressure ventilation with scavenging were inadequate to maintain N(2)O concentration below the OEL value. Air conditioning and an efficient pressure/exhaust ventilation (above 12 air exchanges/h) together with efficient active scavenging systems are sufficient to sustain N(2)O exposure in ORs at levels below or within the OEL value of 180mg/m(3).

Echocardiographic evaluation during weaning from mechanical ventilation.

PubMed

Schifelbain, Luciele Medianeira; Vieira, Silvia Regina Rios; Brauner, Janete Salles; Pacheco, Deise Mota; Naujorks, Alexandre Antonio

2011-01-01

Echocardiographic, electrocardiographic and other cardiorespiratory variables can change during weaning from mechanical ventilation. To analyze changes in cardiac function, using Doppler echocardiogram, in critical patients during weaning from mechanical ventilation, using two different weaning methods: pressure support ventilation and T-tube; and comparing patient subgroups: success vs. failure in weaning. Randomized crossover clinical trial including patients under mechanical ventilation for more than 48 h and considered ready for weaning. Cardiorespiratory variables, oxygenation, electrocardiogram and Doppler echocardiogram findings were analyzed at baseline and after 30 min in pressure support ventilation and T-tube. Pressure support ventilation vs. T-tube and weaning success vs. failure were compared using ANOVA and Student's t-test. The level of significance was p<0.05. Twenty-four adult patients were evaluated. Seven patients failed at the first weaning attempt. No echocardiographic or electrocardiographic differences were observed between pressure support ventilation and T-tube. Weaning failure patients presented increases in left atrium, intraventricular septum thickness, posterior wall thickness and diameter of left ventricle and shorter isovolumetric relaxation time. Successfully weaned patients had higher levels of oxygenation. No differences were observed between Doppler echocardiographic variables and electrocardiographic and other cardiorespiratory variables during pressure support ventilation and T-tube. However cardiac structures were smaller, isovolumetric relaxation time was larger, and oxygenation level was greater in successfully weaned patients.

Clinical review: Positive end-expiratory pressure and cardiac output

PubMed Central

Luecke, Thomas; Pelosi, Paolo

2005-01-01

In patients with acute lung injury, high levels of positive end-expiratory pressure (PEEP) may be necessary to maintain or restore oxygenation, despite the fact that 'aggressive' mechanical ventilation can markedly affect cardiac function in a complex and often unpredictable fashion. As heart rate usually does not change with PEEP, the entire fall in cardiac output is a consequence of a reduction in left ventricular stroke volume (SV). PEEP-induced changes in cardiac output are analyzed, therefore, in terms of changes in SV and its determinants (preload, afterload, contractility and ventricular compliance). Mechanical ventilation with PEEP, like any other active or passive ventilatory maneuver, primarily affects cardiac function by changing lung volume and intrathoracic pressure. In order to describe the direct cardiocirculatory consequences of respiratory failure necessitating mechanical ventilation and PEEP, this review will focus on the effects of changes in lung volume, factors controlling venous return, the diastolic interactions between the ventricles and the effects of intrathoracic pressure on cardiac function, specifically left ventricular function. Finally, the hemodynamic consequences of PEEP in patients with heart failure, chronic obstructive pulmonary disease and acute respiratory distress syndrome are discussed. PMID:16356246

Right ventricular pressure elevated in one-kidney, one clip Goldblatt hypertensive rats.

PubMed

Ketabchi, Farzaneh; Bajoovand, Shirin; Adlband, Mojtaba; Naseh, Maryam; Nekooeian, Ali A; Mashghoolozekr, Elaheh

2017-01-01

Both renal and respiratory diseases are common with high mortality rate around the world. This study was the first to compare effects of two kidneys, one clip (2K1C) and one-kidney, one clip (1K1C) Goldblatt hypertension on right ventricular pressure during normal condition and mechanical ventilation with hypoxia gas. Male Sprague-Dawley rats were subjected to control, 2K1C, or 1K1C groups. Twenty-eight days after the first surgery, animals were anesthetized, and femoral artery and vein, and right ventricle cannulated. Systemic arterial pressure and right ventricular systolic pressures (RVSP) were recorded during ventilation the animals with normoxic or hypoxic gas. RVSP in the 1K1C group was significantly more than the control and 2K1C groups during baseline conditions and ventilation the animals with hypoxic gas. Administration of antioxidant Trolox increased RVSP in the 1K1C and control groups compared with their baselines. Furthermore, there was no alteration in RVSP during hypoxia in the presence of Trolox. This study indicated that RVSP only increased after 28 days induction of 1K1C but not 2K1C model. In addition, it seems that the response to hypoxic gas and antioxidants in 1K1C is more than 2K1C. These data also suggest that effects of 1K1C may partially be related to reactive oxygen species (ROS) pathways.

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.

High-Frequency Percussive Ventilation and Low Tidal Volume Ventilation in Burns: A Randomized Controlled Trial

DTIC Science & Technology

2010-01-01

incidence of ventilator-associated pneumonia ( VAP ) in patients with inha- lation injury when supported with HFPV compared with conventional modes of...mean ratio of PaO2 to FIO2 was 58 6 with a mean positive end- expiratory pressure of 22 2 cm H2O before rescue. Two of these patients were...a sample size of 110 patients in each arm would have been required to detect a difference in VAP with 80% power. A multicentered study would be

Closed loop ventilation mode in Intensive Care Unit: a randomized controlled clinical trial comparing the numbers of manual ventilator setting changes.

PubMed

Arnal, Jean-Michel; Garnero, Aude; Novotni, Dominik; Corno, Gaëlle; Donati, Stéphane-Yannis; Demory, Didier; Quintana, Gabrielle; Ducros, Laurent; Laubscher, Thomas; Durand-Gasselin, Jacques

2018-01-01

There is an equipoise regarding closed-loop ventilation modes and the ability to reduce workload for providers. On one hand some settings are managed by the ventilator but on another hand the automatic mode introduces new settings for the user. This randomized controlled trial compared the number of manual ventilator setting changes between a full closed loop ventilation and oxygenation mode (INTELLiVENT-ASV®) and conventional ventilation modes (volume assist control and pressure support) in Intensive Care Unit (ICU) patients. The secondary endpoints were to compare the number of arterial blood gas analysis, the sedation dose and the user acceptance. Sixty subjects with an expected duration of mechanical ventilation of at least 48 hours were randomized to be ventilated using INTELLiVENT-ASV® or conventional modes with a protocolized weaning. All manual ventilator setting changes were recorded continuously from inclusion to successful extubation or death. Arterial blood gases were performed upon decision of the clinician in charge. User acceptance score was assessed for nurses and physicians once daily using a Likert Scale. The number of manual ventilator setting changes per 24 h-period per subject was lower in INTELLiVENT-ASV® as compared to conventional ventilation group (5 [4-7] versus 10 [7-17]) manuals settings per subject per day [P<0.001]). The number of arterial blood gas analysis and the sedation doses were not significantly different between the groups. Nurses and physicians reported that INTELLiVENT-ASV® was significantly easier to use as compared to conventional ventilation (P<0.001 for nurses and P<0.01 for physicians). For mechanically ventilated ICU patients, INTELLiVENT-ASV® significantly reduces the number of manual ventilator setting changes with the same number of arterial blood gas analysis and sedation dose, and is easier to use for the caregivers as compared to conventional ventilation modes.

Effects of music intervention on physiological stress response and anxiety level of mechanically ventilated patients in China: a randomised controlled trial.

PubMed

Han, Lin; Li, Ji P; Sit, Janet W H; Chung, Loretta; Jiao, Zuo Y; Ma, Wei G

2010-04-01

To examine the effects of music intervention on the physiological stress response and the anxiety level among mechanically ventilated patients in intensive care unit. Despite the fact that previous studies have found music interventions to be effective in stress and anxiety reduction, effects of music on the Chinese population are inconclusive and warranted systematic study to evaluate its effect fully for a different Asian culture. A randomised placebo-controlled trial. A total of 137 patients receiving mechanical ventilation were randomly assigned to either music listening group, headphone group or control group. Outcome measures included the Chinese version of Spielberger State-Trait Anxiety Scale and physiological parameters (heart rate, respiratory rate, saturation of oxygen and blood pressure). Comparison of mean differences (pretest score-posttest score) showed significant differences in heart rate, respiratory rate, systolic blood pressure and diastolic blood pressure as well as the Chinese version of Spielberger State-Trait Anxiety Scale, but not in SaO(2) among the three groups (ranging from p < 0.001 to p = 0.007), of which greater mean differences were found in music listening group. A significant reduction in physiological stress response (heart rate and respiratory rate) over time was found in music listening group (p < 0.001 for both variables) and a significant increase in heart rate and respiratory rate over time in control group (p < 0.001 and p = 0.032), with no significant change over time in headphone group. Within group pretest-posttest comparison of the Chinese version of Spielberger State-Trait Anxiety Scale demonstrated a significant reduction in anxiety for the music listening group (p < 0.001) and headphone group (p < 0.001) but not the control group. Our findings confirm that short-term therapeutic effects of music listening results in substantial reduction in physiological stress responses arising from anxiety in mechanically ventilated patients. Music as a non-pharmacological nursing intervention can be used as complementary adjunct in the care of patients with low-energy states who tire easily, such as those requiring mechanical ventilator support.

Liquid- and Air-Filled Catheters without Balloon as an Alternative to the Air-Filled Balloon Catheter for Measurement of Esophageal Pressure

PubMed Central

Carvalho, Alysson R.; Zin, Walter Araujo; Carvalho, Nadja C.; Huhle, Robert; Giannella-Neto, Antonio; Koch, Thea; de Abreu, Marcelo Gama

2014-01-01

Background Measuring esophageal pressure (Pes) using an air-filled balloon catheter (BC) is the common approach to estimate pleural pressure and related parameters. However, Pes is not routinely measured in mechanically ventilated patients, partly due to technical and practical limitations and difficulties. This study aimed at comparing the conventional BC with two alternative methods for Pes measurement, liquid-filled and air-filled catheters without balloon (LFC and AFC), during mechanical ventilation with and without spontaneous breathing activity. Seven female juvenile pigs (32–42 kg) were anesthetized, orotracheally intubated, and a bundle of an AFC, LFC, and BC was inserted in the esophagus. Controlled and assisted mechanical ventilation were applied with positive end-expiratory pressures of 5 and 15 cmH2O, and driving pressures of 10 and 20 cmH2O, in supine and lateral decubitus. Main Results Cardiogenic noise in BC tracings was much larger (up to 25% of total power of Pes signal) than in AFC and LFC (<3%). Lung and chest wall elastance, pressure-time product, inspiratory work of breathing, inspiratory change and end-expiratory value of transpulmonary pressure were estimated. The three catheters allowed detecting similar changes in these parameters between different ventilation settings. However, a non-negligible and significant bias between estimates from BC and those from AFC and LFC was observed in several instances. Conclusions In anesthetized and mechanically ventilated pigs, the three catheters are equivalent when the aim is to detect changes in Pes and related parameters between different conditions, but possibly not when the absolute value of the estimated parameters is of paramount importance. Due to a better signal-to-noise ratio, and considering its practical advantages in terms of easier calibration and simpler acquisition setup, LFC may prove interesting for clinical use. PMID:25247308

Assessment of the effectiveness of a ventilator associated pneumonia prevention bundle that contains endotracheal tube with subglottic drainage and cuff pressure monitorization.

PubMed

Akdogan, Ozlem; Ersoy, Yasemin; Kuzucu, Ciğdem; Gedik, Ender; Togal, Turkan; Yetkin, Funda

The effectiveness of prevention bundles on the occurrence and mortality of ventilator associated pneumonia (VAP) was evaluated in many studies. However, the effectiveness of endotracheal tube with subglottic secretion drainage (ETT-SD) and cuff pressure monitorization in VAP bundles have not been adequately assessed. In this study, we aimed to evaluate the effectiveness of VAP bundle containing ETT-SD and cuff pressure monitorization. This was a prospective, controlled study that was carried out between March 2011 and April 2012 including intubated patients. The study was conducted at the Anesthesiology Intensive Care Unit 1 and 2 (10 beds each) in a 898-bed university hospital. Occurrence of VAP and compliance with the parameters of the VAP prevention bundles were assessed daily. Patients intubated with the standard endotracheal tube were recruited as controls, mainly in the first six months of the study as ETT-SD and cuff pressure monometer had not yet been implemented. In the second term, patients intubated with ETT-SD were included as cases. Occurrence of VAP, mortality, and compliance with VAP prevention bundles were monitored. A total of 133 patients, 37 cases and 96 controls were recruited. VAP incidence declined from 40.82 to 22.16 per 1000 ventilator days among controls and cases, respectively (p<005). On average, VAP occurred 17.33±21.09 days in the case group and 10.43±7.83 days in the control group (p=0.04). However, mortality of cases and controls at the 14th and 30th days was not different. VAP prevention bundles including the utilization of ETT-SD, monitoring cuff pressure, and oral care with chlorhexidine were efficient in reducing the rate of VAP. Copyright © 2017 Sociedade Brasileira de Infectologia. Published by Elsevier Editora Ltda. All rights reserved.

The efficiency of CO2 elimination during high-frequency jet ventilation for laryngeal microsurgery.

PubMed

Biro, P; Eyrich, G; Rohling, R G

1998-07-01

For adequate and safe use of high-frequency jet ventilation (HFJV), reliable monitoring of the PCO2 status and course is necessary. Because of improved handling and performance, recently available transcutaneous PCO2 monitoring devices such as MicroGas 7650 (Kontron Instruments Medical Sensors, Basel, Switzerland) should enable more effective surveillance of CO2 elimination and, subsequently, better control of subglottic HFJV. Adult patients (n = 164) undergoing laryngeal microsurgery during total i.v. anesthesia were assessed. The resulting transcutaneous PCO2 values, as well as the necessary driving pressure settings, were analyzed to define the CO2 elimination capacity of each patient. Therefore, an individual CO2 elimination coefficient (ECCO2) was calculated. The frequency distribution of the obtained ECCO2 values showed a normal distribution with a median at 0.79 and a range between 0.30 and 2.17. A significant difference in the frequency of obstructive lung disease was found between two patient subpopulations separated by the 25th percentile at an ECCO2 value of 0.63. Other co-factors of CO2 elimination during HFJV were age, gender, and body weight, whereas height and ventilation duration were not involved. We conclude that the individual assessment of ECCO2 enables one to find adequate ventilator settings, resulting in lower airway pressure and less cooling and drying of the tracheobronchial mucosa. CO2 elimination during high-frequency jet ventilation can be assessed by calculating the CO2 elimination coefficient (ECCO2) of each patient from the required driving pressure and the resulting transcutaneous CO2 partial pressure. The frequency distribution of ECCO2 in a typical laryngological patient population was analyzed, and a value of 0.63 was found to be a characteristic limit between sufficient and difficult CO2 elimination. The individual assessment of ECCO2 enables one to find adequate ventilator settings, resulting in lower airway pressure and less cooling and drying of the tracheobronchial mucosa.

Differential lung ventilation via tracheostomy using two endotracheal tubes in an infant: a case report.

PubMed

Demirkol, Demet; Ataman, Yasemin; Gündoğdu, Gökhan

2017-09-08

This case report presents differential lung ventilation in an infant. The aim is to define an alternative technique for performing differential lung ventilation in children. To the best of our knowledge, this is the first report of this kind. A 4.2-kg, 2.5-month-old Asian boy was referred to our facility with refractory hypoxemia and hypercarbia due to asymmetric lung disease with atelectasis of the left lung and hyperinflation of the right lung. He was unresponsive to conventional ventilator strategies; different ventilator settings were required. To perform differential lung ventilation, two separate single-lumen endotracheal tubes were inserted into the main bronchus of each lung by tracheotomy; the tracheal tubes were attached to discrete ventilators. The left lung was ventilated with a lung salvage strategy using high-frequency oscillatory ventilation, and the right lung was ventilated with a lung-protective strategy using pressure-regulated volume control mode. Differential lung ventilation was performed successfully with this technique without complications. Differential lung ventilation may be a lifesaving procedure in select patients who have asymmetric lung disease. Inserting two single-lumen endotracheal tubes via tracheotomy for differential lung ventilation can be an effective and safe alternative method.

Extubation success in premature infants with respiratory distress syndrome treated with bi-level nasal continuous positive airway pressure versus nasal intermittent positive pressure ventilation.

PubMed

Thomas, Patricia E; LeFlore, Judy

2013-01-01

Infants born prematurely with respiratory distress syndrome are at high risk for complications from mechanical ventilation. Strategies are needed to minimize their days on the ventilator. The purpose of this study was to compare extubation success rates in infants treated with 2 different types of continuous positive airway pressure devices. A retrospective cohort study design was used. Data were retrieved from electronic medical records for patients in a large, metropolitan, level III neonatal intensive care unit. A sample of 194 premature infants with respiratory distress syndrome was selected, 124 of whom were treated with nasal intermittent positive pressure ventilation and 70 with bi-level variable flow nasal continuous positive airway pressure (bi-level nasal continuous positive airway pressure). Infants in both groups had high extubation success rates (79% of nasal intermittent positive pressure ventilation group and 77% of bi-level nasal continuous positive airway pressure group). Although infants in the bi-level nasal continuous positive airway pressure group were extubated sooner, there was no difference in duration of oxygen therapy between the 2 groups. Promoting early extubation and extubation success is a vital strategy to reduce complications of mechanical ventilation that adversely affect premature infants with respiratory distress syndrome.

Optimal plateau pressure for patients with acute respiratory distress syndrome: a protocol for a systematic review and meta-analysis with meta-regression.

PubMed

Yasuda, Hideto; Nishimura, Tetsuro; Kamo, Tetsuro; Sanui, Masamitsu; Nango, Eishu; Abe, Takayuki; Takebayashi, Toru; Lefor, Alan Kawarai; Hashimoto, Satoru

2017-05-29

Lower tidal volume ventilation in patients with acute respiratory distress syndrome (ARDS) is a strategy to reduce the plateau pressure and driving pressure to limit ventilator-induced lung injury (VILI). Several randomised controlled trials (RCTs) and meta-analyses showed that limiting both the plateau pressure and the tidal volume decreased mortality, but the optimal plateau pressure to demonstrate a benefit is uncertain. The aim of this systematic review is to investigate the optimal upper limit of plateau pressure in patients with ARDS to prevent VILI and improve clinical outcomes using meta-analysis with and without meta-regression. RCTs comparing two mechanical ventilation strategies will be included, with lower plateau pressure and with higher plateau pressure, among patients with ARDS and acute lung injury. Data sources include MEDLINE via the NCBI Entrez system, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE and Ichushi, a database of papers in Japanese. Two of three physicians will independently screen trials obtained by search for eligibility, and extract data from included studies onto standardised data recording forms. For each included trial, the risk of bias and the quality of evidence will be evaluated using the Grading of Recommendation Assessment Development and Evaluation system. This study does not require ethical approval. The results of this systematic review and meta-analysis with and without meta-regression will be disseminated through conference presentation and publication in a peer-reviewed journal. CRD42016041924. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Unloading work of breathing during high-frequency oscillatory ventilation: a bench study

PubMed Central

van Heerde, Marc; Roubik, Karel; Kopelent, Vitek; Plötz, Frans B; Markhorst, Dick G

2006-01-01

Introduction With the 3100B high-frequency oscillatory ventilator (SensorMedics, Yorba Linda, CA, USA), patients' spontaneous breathing efforts result in a high level of imposed work of breathing (WOB). Therefore, spontaneous breathing often has to be suppressed during high-frequency oscillatory ventilation (HFOV). A demand-flow system was designed to reduce imposed WOB. Methods An external gas flow controller (demand-flow system) accommodates the ventilator fresh gas flow during spontaneous breathing simulation. A control algorithm detects breathing effort and regulates the demand-flow valve. The effectiveness of this system has been evaluated in a bench test. The Campbell diagram and pressure time product (PTP) are used to quantify the imposed workload. Results Using the demand-flow system, imposed WOB is considerably reduced. The demand-flow system reduces inspiratory imposed WOB by 30% to 56% and inspiratory imposed PTP by 38% to 59% compared to continuous fresh gas flow. Expiratory imposed WOB was decreased as well by 12% to 49%. In simulations of shallow to normal breathing for an adult, imposed WOB is 0.5 J l-1 at maximum. Fluctuations in mean airway pressure on account of spontaneous breathing are markedly reduced. Conclusion The use of the demand-flow system during HFOV results in a reduction of both imposed WOB and fluctuation in mean airway pressure. The level of imposed WOB was reduced to the physiological range of WOB. Potentially, this makes maintenance of spontaneous breathing during HFOV possible and easier in a clinical setting. Early initiation of HFOV seems more possible with this system and the possibility of weaning of patients directly on a high-frequency oscillatory ventilator is not excluded either. PMID:16848915

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.

Preparing Technical Requirements for Third Party Contracting of Army Facilities

DTIC Science & Technology

1993-06-01

Boiler and Pressure Vessel Code Sec 9 Welding and Brazing Qualifications B 16.1 Cast Iron Pipe Flanges and Flanged...Control Terminology for Heating, Ventilating, Air Conditioning American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code B40.1...American National Standards Institute (ANSI) Boiler and Pressure Vessel Code (ASME) 125 Boilers and Pressure Vessels Code (ASTM) B31 Power

Non-invasive positive pressure ventilation during sleep at 3800 m: Relationship to acute mountain sickness and sleeping oxyhaemoglobin saturation.

PubMed

Johnson, Pamela L; Popa, Daniel A; Prisk, G Kim; Edwards, Natalie; Sullivan, Colin E

2010-02-01

Overnight oxyhaemoglobin desaturation is related to AMS. AMS can be debilitating and may require descent. Positive pressure ventilation during sleep at high altitude may prevent AMS and therefore be useful in people travelling to high altitude, who are known to suffer from AMS. Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep. We compared sleeping oxyhaemoglobin saturation and the incidence and severity of AMS in seven subjects sleeping for two consecutive nights at 3800 m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of AMS were assessed by administration of the Lake Louise questionnaire. We found significant increases in the mean and minimum sleeping oxyhaemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. The use of positive pressure ventilation during sleep at 3800 m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation.

Tracheal Tube Design and Ventilator-Associated Pneumonia.

PubMed

Rouzé, Anahita; Jaillette, Emmanuelle; Poissy, Julien; Préau, Sébastien; Nseir, Saad

2017-10-01

Microaspiration of contaminated oropharyngeal and gastric secretions is the main mechanism for ventilator-associated pneumonia (VAP) in critically ill patients. Improving the performance of tracheal tubes in reducing microaspiration is one potential means to prevent VAP. The aim of this narrative review is to discuss recent findings on the impact of tracheal tube design on VAP prevention. Several randomized controlled studies have reported that subglottic secretion drainage (SSD) is efficient in VAP prevention. Meta-analyses have reported conflicting results regarding the impact of SSD on duration of mechanical ventilation, and one animal study raised concern about SSD-related tracheal lesions. However, this measure appears to be cost-effective. Therefore, SSD should probably be used in all patients with expected duration of mechanical ventilation > 48 h. Three randomized controlled trials have shown that tapered-cuff tracheal tubes are not useful to prevent VAP and should probably not be used in critically ill patients. Further studies are required to confirm the promising effects of continuous control of cuff pressure, polyurethane-cuffed, silver-coated, and low-volume low-pressure tracheal tubes. There is moderate evidence for the use of SSD and strong evidence against the use of tapered-cuff tracheal tubes in critically ill patients for VAP prevention. However, more data on the safety and cost-effectiveness of these measures are needed. Other tracheal tube-related preventive measures require further investigation. Copyright © 2017 by Daedalus Enterprises.

Closed-loop mechanical ventilation for lung injury: a novel physiological-feedback mode following the principles of the open lung concept.

PubMed

Schwaiberger, David; Pickerodt, Philipp A; Pomprapa, Anake; Tjarks, Onno; Kork, Felix; Boemke, Willehad; Francis, Roland C E; Leonhardt, Steffen; Lachmann, Burkhard

2018-06-01

Adherence to low tidal volume (V T ) ventilation and selected positive end-expiratory pressures are low during mechanical ventilation for treatment of the acute respiratory distress syndrome. Using a pig model of severe lung injury, we tested the feasibility and physiological responses to a novel fully closed-loop mechanical ventilation algorithm based on the "open lung" concept. Lung injury was induced by surfactant washout in pigs (n = 8). Animals were ventilated following the principles of the "open lung approach" (OLA) using a fully closed-loop physiological feedback algorithm for mechanical ventilation. Standard gas exchange, respiratory- and hemodynamic parameters were measured. Electrical impedance tomography was used to quantify regional ventilation distribution during mechanical ventilation. Automatized mechanical ventilation provided strict adherence to low V T -ventilation for 6 h in severely lung injured pigs. Using the "open lung" approach, tidal volume delivery required low lung distending pressures, increased recruitment and ventilation of dorsal lung regions and improved arterial blood oxygenation. Physiological feedback closed-loop mechanical ventilation according to the principles of the open lung concept is feasible and provides low tidal volume ventilation without human intervention. Of importance, the "open lung approach"-ventilation improved gas exchange and reduced lung driving pressures by opening atelectasis and shifting of ventilation to dorsal lung regions.

Echocardiographic evaluation during weaning from mechanical ventilation

PubMed Central

Schifelbain, Luciele Medianeira; Vieira, Silvia Regina Rios; Brauner, Janete Salles; Pacheco, Deise Mota; Naujorks, Alexandre Antonio

2011-01-01

INTRODUCTION: Echocardiographic, electrocardiographic and other cardiorespiratory variables can change during weaning from mechanical ventilation. OBJECTIVES: To analyze changes in cardiac function, using Doppler echocardiogram, in critical patients during weaning from mechanical ventilation, using two different weaning methods: pressure support ventilation and T‐tube; and comparing patient subgroups: success vs. failure in weaning. METHODS: Randomized crossover clinical trial including patients under mechanical ventilation for more than 48 h and considered ready for weaning. Cardiorespiratory variables, oxygenation, electrocardiogram and Doppler echocardiogram findings were analyzed at baseline and after 30 min in pressure support ventilation and T‐tube. Pressure support ventilation vs. T‐tube and weaning success vs. failure were compared using ANOVA and Student's t‐test. The level of significance was p<0.05. RESULTS: Twenty‐four adult patients were evaluated. Seven patients failed at the first weaning attempt. No echocardiographic or electrocardiographic differences were observed between pressure support ventilation and T‐tube. Weaning failure patients presented increases in left atrium, intraventricular septum thickness, posterior wall thickness and diameter of left ventricle and shorter isovolumetric relaxation time. Successfully weaned patients had higher levels of oxygenation. CONCLUSION: No differences were observed between Doppler echocardiographic variables and electrocardiographic and other cardiorespiratory variables during pressure support ventilation and T‐tube. However cardiac structures were smaller, isovolumetric relaxation time was larger, and oxygenation level was greater in successfully weaned patients. PMID:21437445

Haemodynamics, dyspnoea, and pulmonary reserve in heart failure with preserved ejection fraction.

PubMed

Obokata, Masaru; Olson, Thomas P; Reddy, Yogesh N V; Melenovsky, Vojtech; Kane, Garvan C; Borlaug, Barry A

2018-05-19

Increases in left ventricular filling pressure are a fundamental haemodynamic abnormality in heart failure with preserved ejection fraction (HFpEF). However, very little is known regarding how elevated filling pressures cause pulmonary abnormalities or symptoms of dyspnoea. We sought to determine the relationships between simultaneously measured central haemodynamics, symptoms, and lung ventilatory and gas exchange abnormalities during exercise in HFpEF. Subjects with invasively-proven HFpEF (n = 50) and non-cardiac causes of dyspnoea (controls, n = 24) underwent cardiac catheterization at rest and during exercise with simultaneous expired gas analysis. During submaximal (20 W) exercise, subjects with HFpEF displayed higher pulmonary capillary wedge pressures (PCWP) and pulmonary artery pressures, higher Borg perceived dyspnoea scores, and increased ventilatory drive and respiratory rate. At peak exercise, ventilation reserve was reduced in HFpEF compared with controls, with greater dead space ventilation (higher VD/VT). Increasing exercise PCWP was directly correlated with higher perceived dyspnoea scores, lower peak exercise capacity, greater ventilatory drive, worse New York Heart Association (NYHA) functional class, and impaired pulmonary ventilation reserve. This study provides the first evidence linking altered exercise haemodynamics to pulmonary abnormalities and symptoms of dyspnoea in patients with HFpEF. Further study is required to identify the mechanisms by which haemodynamic derangements affect lung function and symptoms and to test novel therapies targeting exercise haemodynamics in HFpEF.

Pulse pressure variation-guided fluid therapy after cardiac surgery: a pilot before-and-after trial.

PubMed

Suzuki, Satoshi; Woinarski, Nicholas C Z; Lipcsey, Miklos; Candal, Cristina Lluch; Schneider, Antoine G; Glassford, Neil J; Eastwood, Glenn M; Bellomo, Rinaldo

2014-12-01

The aim of this study is to study the feasibility, safety, and physiological effects of pulse pressure variation (PPV)-guided fluid therapy in patients after cardiac surgery. We conducted a pilot prospective before-and-after study during mandatory ventilation after cardiac surgery in a tertiary intensive care unit. We introduced a protocol to deliver a fluid bolus for a PPV≥13% for at least >10 minutes during the intervention period. We studied 45 control patients and 53 intervention patients. During the intervention period, clinicians administered a fluid bolus on 79% of the defined PPV trigger episodes. Median total fluid intake was similar between 2 groups during mandatory ventilation (1297 mL [interquartile range 549-1968] vs 1481 mL [807-2563]; P=.17) and the first 24 hours (3046 mL [interquartile range 2317-3982] vs 3017 mL [2192-4028]; P=.73). After adjusting for several baseline factors, PPV-guided fluid management significantly increased fluid intake during mandatory ventilation (P=.004) but not during the first 24 hours (P=.47). Pulse pressure variation-guided fluid therapy, however, did not significantly affect hemodynamic, renal, and metabolic variables. No serious adverse events were noted. Pulse pressure variation-guided fluid management was feasible and safe during mandatory ventilation after cardiac surgery. However, its advantages may be clinically small. Copyright © 2014 Elsevier Inc. All rights reserved.

Lung ventilation injures areas with discrete alveolar flooding, in a surface tension-dependent fashion.

PubMed

Wu, You; Kharge, Angana Banerjee; Perlman, Carrie E

2014-10-01

With proteinaceous-liquid flooding of discrete alveoli, a model of the edema pattern in the acute respiratory distress syndrome, lung inflation over expands aerated alveoli adjacent to flooded alveoli. Theoretical considerations suggest that the overexpansion may be proportional to surface tension, T. Yet recent evidence indicates proteinaceous edema liquid may not elevate T. Thus whether the overexpansion is injurious is not known. Here, working in the isolated, perfused rat lung, we quantify fluorescence movement from the vasculature to the alveolar liquid phase as a measure of overdistension injury to the alveolar-capillary barrier. We label the perfusate with fluorescence; micropuncture a surface alveolus and instill a controlled volume of nonfluorescent liquid to obtain a micropunctured-but-aerated region (control group) or a region with discrete alveolar flooding; image the region at a constant transpulmonary pressure of 5 cmH2O; apply five ventilation cycles with a positive end-expiratory pressure of 0-20 cmH2O and tidal volume of 6 or 12 ml/kg; return the lung to a constant transpulmonary pressure of 5 cmH2O; and image for an additional 10 min. In aerated areas, ventilation is not injurious. With discrete alveolar flooding, all ventilation protocols cause sustained injury. Greater positive end-expiratory pressure or tidal volume increases injury. Furthermore, we determine T and find injury increases with T. Inclusion of either plasma proteins or Survanta in the flooding liquid does not alter T or injury. Inclusion of 2.7-10% albumin and 1% Survanta together, however, lowers T and injury. Contrary to expectation, albumin inclusion in our model facilitates exogenous surfactant activity. Copyright © 2014 the American Physiological Society.

Lung ventilation injures areas with discrete alveolar flooding, in a surface tension-dependent fashion

PubMed Central

Wu (吴右), You; Kharge, Angana Banerjee

2014-01-01

With proteinaceous-liquid flooding of discrete alveoli, a model of the edema pattern in the acute respiratory distress syndrome, lung inflation over expands aerated alveoli adjacent to flooded alveoli. Theoretical considerations suggest that the overexpansion may be proportional to surface tension, T. Yet recent evidence indicates proteinaceous edema liquid may not elevate T. Thus whether the overexpansion is injurious is not known. Here, working in the isolated, perfused rat lung, we quantify fluorescence movement from the vasculature to the alveolar liquid phase as a measure of overdistension injury to the alveolar-capillary barrier. We label the perfusate with fluorescence; micropuncture a surface alveolus and instill a controlled volume of nonfluorescent liquid to obtain a micropunctured-but-aerated region (control group) or a region with discrete alveolar flooding; image the region at a constant transpulmonary pressure of 5 cmH2O; apply five ventilation cycles with a positive end-expiratory pressure of 0–20 cmH2O and tidal volume of 6 or 12 ml/kg; return the lung to a constant transpulmonary pressure of 5 cmH2O; and image for an additional 10 min. In aerated areas, ventilation is not injurious. With discrete alveolar flooding, all ventilation protocols cause sustained injury. Greater positive end-expiratory pressure or tidal volume increases injury. Furthermore, we determine T and find injury increases with T. Inclusion of either plasma proteins or Survanta in the flooding liquid does not alter T or injury. Inclusion of 2.7–10% albumin and 1% Survanta together, however, lowers T and injury. Contrary to expectation, albumin inclusion in our model facilitates exogenous surfactant activity. PMID:25080924

In-flight cabin smoke control.

PubMed

Eklund, T I

1996-12-31

Fatal accidents originating from in-flight cabin fires comprise only about 1% of all fatal accidents in the civil jet transport fleet. Nevertheless, the impossibility of escape during flight accentuates the hazards resulting from low visibility and toxic gases. Control of combustion products in an aircraft cabin is affected by several characteristics that make the aircraft cabin environment unique. The aircraft fuselage is pressurized in flight and has an air distribution system which provides ventilation jets from the ceiling level air inlets running along the cabin length. A fixed quantity of ventilation air is metered into the cabin and air discharge is handled primarily by pressure controlling outflow valves in the rear lower part of the fuselage. Earlier airplane flight tests on cabin smoke control used generators producing minimally buoyant smoke products that moved with and served as a telltales for overall cabin ventilation flows. Analytical studies were done with localized smoke production to predict the percent of cabin length that would remain smoke-free during continuous generation. Development of a buoyant smoke generator allowed simulation of a fire plume with controllable simulated temperature and heat release rates. Tests on a Boeing 757, modified to allow smoke venting out through the top of the cabin, showed that the buoyant smoke front moved at 0.46m/s (1.5ft/sec) with and 0.27m/sec (0.9ft/sec) against, the axial ventilation airflow. Flight tests in a modified Boeing 727 showed that a ceiling level counterflow of about 0.55m/sec (1.8ft/sec) was required to arrest the forward movement of buoyant smoke. A design goal of 0.61m/s (2ft/sec) axial cabin flow would require a flow rate of 99m3/min (3500ft3/min) in a furnished Boeing 757. The current maximum fresh air cabin ventilation flow is 78m3/min (2756 ft3/min). Experimental results indicate that buoyancy effects cause smoke movement behaviour that is not predicted by traditional design analyses and flight test methodologies. Augmenting available ventilation for smoke control remains a design and safety challenge.

Upper Airway Collapsibility During REM Sleep in Children with the Obstructive Sleep Apnea Syndrome

PubMed Central

Huang, Jingtao; Karamessinis, Laurie R.; Pepe, Michelle E.; Glinka, Stephen M.; Samuel, John M.; Gallagher, Paul R.; Marcus, Carole L.

2009-01-01

Study Objectives: In children, most obstructive events occur during rapid eye movement (REM) sleep. We hypothesized that children with the obstructive sleep apnea syndrome (OSAS), in contrast to age-matched control subjects, would not maintain airflow in the face of an upper airway inspiratory pressure drop during REM sleep. Design: During slow wave sleep (SWS) and REM sleep, we measured airflow, inspiratory time, inspiratory time/total respiratory cycle time, respiratory rate, tidal volume, and minute ventilation at a holding pressure at which flow limitation occurred and at 5 cm H2O below the holding pressure in children with OSAS and in control subjects. Setting: Sleep laboratory. Participants: Fourteen children with OSAS and 23 normal control subjects. Results: In both sleep states, control subjects were able to maintain airflow, whereas subjects with OSAS preserved airflow in SWS but had a significant decrease in airflow during REM sleep (change in airflow of 18.58 ± 12.41 mL/s for control subjects vs −44.33 ± 14.09 mL/s for children with OSAS, P = 0.002). Although tidal volume decreased, patients with OSAS were able to maintain minute ventilation by increasing the respiratory rate and also had an increase in inspiratory time and inspiratory time per total respiratory cycle time Conclusion: Children with OSAS do not maintain airflow in the face of upper-airway inspiratory-pressure drops during REM sleep, indicating a more collapsible upper airway, compared with that of control subjects during REM sleep. However, compensatory mechanisms exist to maintain minute ventilation. Local reflexes, central control mechanisms, or both reflexes and control mechanisms need to be further explored to better understand the pathophysiology of this abnormality and the compensation mechanism. Citation: Huang J; Karamessinis LR; Pepe ME; Glinka SM; Samuel JM; Gallagher PR; Marcus CL. Upper airway collapsibility during REM sleep in children with the obstructive sleep apnea syndrome. SLEEP 2009;32(9):1173-1181. PMID:19750922

Design and Development of a Regenerative Blower for EVA Suit Ventilation

NASA Technical Reports Server (NTRS)

Izenson, Michael G.; Chen, Weibo; Hill, Roger W.; Phillips, Scott D.; Paul, Heather L.

2011-01-01

Ventilation subsystems in future space suits require a dedicated ventilation fan. The unique requirements for the ventilation fan - including stringent safety requirements and the ability to increase output to operate in buddy mode - combine to make a regenerative blower an attractive choice. This paper describes progress in the design, development, and testing of a regenerative blower designed to meet requirements for ventilation subsystems in future space suits. We have developed analysis methods for the blower s complex, internal flows and identified impeller geometries that enable significant improvements in blower efficiency. We verified these predictions by test, measuring aerodynamic efficiencies of 45% at operating conditions that correspond to the ventilation fan s design point. We have developed a compact motor/controller to drive the blower efficiently at low rotating speed (4500 rpm). Finally, we have assembled a low-pressure oxygen test loop to demonstrate the blower s reliability under prototypical conditions.

LMA Supreme for neonatal resuscitation: study protocol for a randomized controlled trial

PubMed Central

2014-01-01

Background The most important action in the resuscitation of a newborn in the delivery room is to establish effective assisted ventilation. The face mask and endotracheal tube are the devices used to achieve this goal. Laryngeal mask airways that fit over the laryngeal inlet have been shown to be effective for ventilating newborns at birth and should be considered as an alternative to facemask ventilation or endotracheal intubation among newborns weighing >2,000 g or delivered ≥34 weeks’ gestation. A recent systematic review and meta-analysis of supraglottic airways in neonatal resuscitation reported the results of four randomized controlled trials (RCTs) stating that fewer infants in the group using laryngeal mask airways required endotracheal intubation (1.5%) compared to the group using face masks (12.0%). However, there were methodological concerns over all the RCTs including the fact that the majority of the operators in the trials were anesthesiologists. Our hypothesis is based on the assumption that ventilating newborns needing positive pressure ventilation with a laryngeal mask airway will be more effective than ventilating with a face mask in a setting where neonatal resuscitation is performed by midwives, nurses, and pediatricians. The primary aim of this study will be to assess the effectiveness of the laryngeal mask airway over the face mask in preventing the need for endotracheal intubation. Methods/design This will be an open, prospective, randomized, single center, clinical trial. In this study, 142 newborns weighing >1,500 g or delivered ≥34 weeks gestation needing positive pressure ventilation at birth will be randomized to be ventilated with a laryngeal mask airway (LMA SupremeTM, LMA Company, UK - intervention group) or with a face mask (control group). Primary outcome: Proportion of newborns needing endotracheal intubation. Secondary outcomes: Apgar score at 5 minutes, time to first breath, onset of the first cry, duration of resuscitation, death or moderate to severe hypoxic-ischemic encephalopathy within 7 days of life. Trial registration ClinicalTrials.gov identifier: NCT01963936 (October 11, 2013). PMID:25027230

The effect of flow limitation on the cardiorespiratory response to arousal from sleep under controlled conditions of chemostimulation in healthy older adults.

PubMed

Goff, Elizabeth A; Nicholas, Christian L; Kleiman, Jan; Spear, Owen; Morrell, Mary J; Trinder, John

2012-12-01

The influence of flow limitation on the magnitude of the cardiorespiratory response to arousal from sleep is of interest in older people, because they experience considerable flow limitation and frequent arousals from sleep. We studied older flow-limiting subjects, testing the hypothesis that the cardiorespiratory activation response would be larger when arousal occurred during flow limitation, compared to no flow limitation, and chemical stimuli were controlled. In 11 older adults [mean ± standard deviation (SD) age: 68 ± 5 years] ventilation was stabilized using continuous positive airway pressure, and flow limitation was induced by dialling down the pressure. Partial pressure of end-tidal carbon dioxide (PetCO(2)) was maintained by titration of the inspired CO(2) and hyperoxia was maintained using 40% O(2) balanced with nitrogen. Flow limitation at the time of arousal did not augment cardiovascular activation response (heart rate P = 0.7; systolic blood pressure P = 0.6; diastolic blood pressure P = 0.3), whereas ventilation was greater following arousals during flow limitation compared to no flow limitation (P < 0.001). The pre-post-arousal differences in ventilation reflected significant pre-arousal suppression (due to flow limitation) plus post-arousal activation. In summary, the cardiovascular response to arousal from sleep is not influenced by flow limitation at the time of arousal, when chemical stimuli are controlled in older adults. This finding may contribute to the decreased cardiovascular burden associated with sleep-disordered breathing reported in older adults, although our data do not exclude the possibility that flow limitation in the presence of mild hypoxic hypercapnia could increase the cardiovascular response to arousal. © 2012 European Sleep Research Society.

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).

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.

Non-invasive positive-pressure ventilation with positive end-expiratory pressure counteracts inward air leaks during preoxygenation: a randomised crossover controlled study in healthy volunteers.

PubMed

Hanouz, J-L; Le Gall, F; Gérard, J-L; Terzi, N; Normand, H

2018-04-01

During preoxygenation, the lack of tight fit between the mask and the patient's face results in inward air leak preventing effective preoxygenation. We hypothesized that non-invasive positive-pressure ventilation and positive end-expiratory pressure (PEEP) could counteract inward air leak. Healthy volunteers were randomly assigned to preoxygenated through spontaneous breathing without leak (SB), spontaneous breathing with a calibrated air leak (T-shaped piece between the mouth and the breathing system; SB-leak), or non-invasive positive inspiratory pressure ventilation (inspiratory support +6 cm H 2 O; PEEP +5 cm H 2 O) with calibrated leak (PPV-leak). The volunteers breathed through a mouthpiece connected to an anaesthesia ventilator. The expired oxygen fraction (FeO 2 ) and air-leak flow (ml s -1 ) were measured. The primary end point was the proportion of volunteers with FeO 2 >90% at 3 min. The secondary end points were FeO 2 at 3 min, time to reach FeO 2 of 90%, and the inspiratory air-leak flow. Twenty healthy volunteers were included. The proportion of volunteers with FeO 2 >90% at 3 min was 0% in the SB-leak group, 95% in the SB group, and 100% in the PPV-leak group (P<0.001). At 3 min, the mean [standard deviation (sd)] FeO 2 was 89 (1)%, 76 (1)%, and 90 (0)% in the SB, SB-leak, and PPV-leak groups, respectively (P<0.001). The mean (sd) inward air leak was 59 (12) ml s -1 in the SB-leak group, but 0 (0) ml s -1 in the PPV-leak group (P<0.001). Preoxygenation through non-invasive positive-pressure ventilation and PEEP provided effective preoxygenation despite an inward air leak. NCT03087825. Copyright © 2017 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.

A Turbine-Driven Ventilator Improves Adherence to Advanced Cardiac Life Support Guidelines During a Cardiopulmonary Resuscitation Simulation.

PubMed

Allen, Scott G; Brewer, Lara; Gillis, Erik S; Pace, Nathan L; Sakata, Derek J; Orr, Joseph A

2017-09-01

Research has shown that increased breathing frequency during cardiopulmonary resuscitation is inversely correlated with systolic blood pressure. Rescuers often hyperventilate during cardiopulmonary resuscitation (CPR). Current American Heart Association advanced cardiac life support recommends a ventilation rate of 8-10 breaths/min. We hypothesized that a small, turbine-driven ventilator would allow rescuers to adhere more closely to advanced cardiac life support (ACLS) guidelines. Twenty-four ACLS-certified health-care professionals were paired into groups of 2. Each team performed 4 randomized rounds of 2-min cycles of CPR on an intubated mannikin, with individuals altering between compressions and breaths. Two rounds of CPR were performed with a self-inflating bag, and 2 rounds were with the ventilator. The ventilator was set to deliver 8 breaths/min, pressure limit 22 cm H 2 O. Frequency, tidal volume (V T ), peak inspiratory pressure, and compression interruptions (hands-off time) were recorded. Data were analyzed with a linear mixed model and Welch 2-sample t test. The median (interquartile range [IQR]) frequency with the ventilator was 7.98 (7.98-7.99) breaths/min. Median (IQR) frequency with the self-inflating bag was 9.5 (8.2-10.7) breaths/min. Median (IQR) ventilator V T was 0.5 (0.5-0.5) L. Median (IQR) self-inflating bag V T was 0.6 (0.5-0.7) L. Median (IQR) ventilator peak inspiratory pressure was 22 (22-22) cm H 2 O. Median (IQR) self-inflating bag peak inspiratory pressure was 30 (27-35) cm H 2 O. Mean ± SD hands-off times for ventilator and self-inflating bag were 5.25 ± 2.11 and 6.41 ± 1.45 s, respectively. When compared with a ventilator, volunteers ventilated with a self-inflating bag within ACLS guidelines. However, volunteers ventilated with increased variation, at higher V T levels, and at higher peak pressures with the self-inflating bag. Hands-off time was also significantly lower with the ventilator. (ClinicalTrials.gov registration NCT02743299.). Copyright © 2017 by Daedalus Enterprises.

A dynamic ventilation model for gravity sewer networks.

PubMed

Wang, Y C; Nobi, N; Nguyen, T; Vorreiter, L

2012-01-01

To implement any effective odour and corrosion control technology in the sewer network, it is imperative that the airflow through gravity sewer airspaces be quantified. This paper presents a full dynamic airflow model for gravity sewer systems. The model, which is developed using the finite element method, is a compressible air transport model. The model has been applied to the North Head Sewerage Ocean Outfall System (NSOOS) and calibrated using the air pressure and airflow data collected during October 2008. Although the calibration is focused on forced ventilation, the model can be applied to natural ventilation as well.

A microprocessor-controlled tracheal insufflation-assisted total liquid ventilation system.

PubMed

Parker, James Courtney; Sakla, Adel; Donovan, Francis M; Beam, David; Chekuri, Annu; Al-Khatib, Mohammad; Hamm, Charles R; Eyal, Fabien G

2009-09-01

A prototype time cycled, constant volume, closed circuit perfluorocarbon (PFC) total liquid ventilator system is described. The system utilizes microcontroller-driven display and master control boards, gear motor pumps, and three-way solenoid valves to direct flow. A constant tidal volume and functional residual capacity (FRC) are maintained with feedback control using end-expiratory and end-inspiratory stop-flow pressures. The system can also provide a unique continuous perfusion (bias flow, tracheal insufflation) through one lumen of a double-lumen endotracheal catheter to increase washout of dead space liquid. FRC and arterial blood gases were maintained during ventilation with Rimar 101 PFC over 2-3 h in normal piglets and piglets with simulated pulmonary edema induced by instillation of albumin solution. Addition of tracheal insufflation flow significantly improved the blood gases and enhanced clearance of instilled albumin solution during simulated edema.

A randomized prospective controlled trial comparing the laryngeal tube suction disposable and the supreme laryngeal mask airway: the influence of head and neck position on oropharyngeal seal pressure.

PubMed

Somri, Mostafa; Vaida, Sonia; Garcia Fornari, Gustavo; Mendoza, Gabriela Renee; Charco-Mora, Pedro; Hawash, Naser; Matter, Ibrahim; Swaid, Forat; Gaitini, Luis

2016-10-06

The Laryngeal Tube Suction Disposable (LTS-D) and the Supreme Laryngeal Mask Airway (SLMA) are second generation supraglottic airway devices (SADs) with an added channel to allow gastric drainage. We studied the efficacy of these devices when using pressure controlled mechanical ventilation during general anesthesia for short and medium duration surgical procedures and compared the oropharyngeal seal pressure in different head and-neck positions. Eighty patients in each group had either LTS-D or SLMA for airway management. The patients were recruited in two different institutions. Primary outcome variables were the oropharyngeal seal pressures in neutral, flexion, extension, right and left head-neck position. Secondary outcome variables were time to achieve an effective airway, ease of insertion, number of attempts, maneuvers necessary during insertion, ventilatory parameters, success of gastric tube insertion and incidence of complications. The oropharyngeal seal pressure achieved with the LTS-D was higher than the SLMA in, (extension (p=0.0150) and right position (p=0.0268 at 60 cm H 2 O intracuff pressures and nearly significant in neutral position (p = 0.0571). The oropharyngeal seal pressure was significantly higher with the LTS-D during neck extension as compared to SLMA (p= 0.015). Similar oropharyngeal seal pressures were detected in all other positions with each device. The secondary outcomes were comparable between both groups. Patients ventilated with LTS-D had higher incidence of sore throat (p = 0.527). No major complications occurred. Better oropharyngeal seal pressure was achieved with the LTS-D in head-neck right and extension positions , although it did not appear to have significance in alteration of management using pressure control mechanical ventilation in neutral position. The fiberoptic view was better with the SLMA. The post-operative sore throat incidence was higher in the LTS-D. ClinicalTrials.gov ID: NCT02856672 , Unique Protocol ID:BnaiZionMC-16-LG-001, Registered: August 2016.

Home noninvasive positive pressure ventilation with built-in software in stable hypercapnic COPD: a short-term prospective, multicenter, randomized, controlled trial.

PubMed

Zhou, Luqian; Li, Xiaoying; Guan, Lili; Chen, Jianhua; Guo, Bingpeng; Wu, Weiliang; Huo, Yating; Zhou, Ziqing; Liang, Zhenyu; Zhou, Yuqi; Tan, Jie; Chen, Xin; Song, Yuanlin; Chen, Rongchang

2017-01-01

The benefits of noninvasive positive pressure ventilation (NPPV) in patients with hypercapnic COPD are controversial. It is presumed that methodology and appropriate use of NIV ventilator might be crucial for the outcomes. With the new built-in software, the performance of NIV can be monitored at home, which can guarantee the compliance and appropriate use. This study investigated effects of home use of NIV in hypercapnia in COPD patients using the NIV ventilator with built-in software for monitoring. The current multicenter prospective, randomized, controlled trial enrolled patients with stable GOLD stages III and IV hypercapnic COPD. Patients were randomly assigned via a computer-generated randomization sequence, with a block size of four patients, to continue optimized treatment (control group) or to receive additional NPPV (intervention group) for 3 months. The primary outcome was arterial carbon dioxide pressure (PaCO 2 ). Data were derived from built-in software and analyzed every 4 weeks. Analysis was carried out with the intention to treat. This study is registered with ClinicalTrials.gov, number NCT02499718. Patients were recruited from 20 respiratory units in China from October 1, 2015, and recruitment was terminated with a record of the vital statistics on May 31, 2016. A total of 115 patients were randomly assigned to the NPPV group (n=57) or the control group (n=58). Patients complied well with NPPV therapy (mean [± standard deviation] day use 5.6±1.4 h). The mean estimation of leaks was 37.99±13.71 L/min. The changes in PaCO 2 (-10.41±0.97 vs -4.32±0.68 mmHg, P =0.03) and 6-min walk distance (6MWD) (38.2% vs 18.2%, P =0.02) were statistically significant in the NPPV group versus the control group. COPD assessment test (CAT) showed a positive trend ( P =0.06) in favor of the NPPV group. Pulmonary function and dyspnea were not different between groups. Ventilators equipped with built-in software provided methodology for monitoring NIV use at home, which could facilitate the improvement of compliance and quality control of NIV use. It was shown that three months use of NIV at home could reduce the PaCO 2 and improve exercise tolerance (6MWD) in chronic hypercapnic COPD patients.

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

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.

Non-invasive Positive Pressure Ventilation during Sleep at 3800m: relationship to Acute Mountain Sickness and sleeping oxyhemoglobin saturation

PubMed Central

Johnson, PL; Popa, DA; Prisk, GK; Sullivan, CE; Edwards, N

2014-01-01

Background and objectives Ascent to high altitude results in hypobaric hypoxia and some individuals will develop Acute Mountain Sickness, which has been shown to be associated with low oxyhemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake, results in a reduction in AMS symptoms and higher oxyhemoglobin saturation. We aimed to test whether pressure ventilation during sleep would prevent AMS by keeping oxyhaemoglobin higher during sleep. Methods We compared sleeping oxyhemoglobin saturation and the incidence and severity of Acute Mountain Sickness in seven subjects sleeping for two consecutive nights at 3800m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of Acute Mountain Sickness was assessed by administration of the Lake Louise questionnaire. Results We found significant increases in the mean and minimum sleeping oxyhemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. Conclusion The use of positive pressure ventilation during sleep at 3800m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation. PMID:20051046

Feasibility of Protective Ventilation During Elective Supratentorial Neurosurgery: A Randomized, Crossover, Clinical Trial.

PubMed

Ruggieri, Francesco; Beretta, Luigi; Corno, Laura; Testa, Valentina; Martino, Enrico A; Gemma, Marco

2017-06-30

Traditional ventilation approaches, providing high tidal volumes (Vt), produce excessive alveolar distention and lung injury. Protective ventilation, employing lower Vt and positive end-expiratory pressure (PEEP), is an attractive alternative also for neuroanesthesia, when prolonged mechanical ventilation is needed. Nevertheless, protective ventilation during intracranial surgery may exert dangerous effects on intracranial pressure (ICP). We tested the feasibility of a protective ventilation strategy in neurosurgery. Our monocentric, double-blind, 1:1 randomized, 2×2 crossover study aimed at studying the effect size and variability of ICP in patients undergoing elective supratentorial brain tumor removal and alternatively ventilated with Vt 9 mL/kg-PEEP 0 mm Hg and Vt 7 mL/kg-PEEP 5 mm Hg. Respiratory rate was adjusted to maintain comparable end-tidal carbon dioxide between ventilation modes. ICP was measured through a subdural catheter inserted before dural opening. Forty patients were enrolled; 8 (15%) were excluded after enrollment. ICP did not differ between traditional and protective ventilation (11.28±5.37, 11 [7 to 14.5] vs. 11.90±5.86, 11 [8 to 15] mm Hg; P=0.541). End-tidal carbon dioxide (28.91±2.28, 29 [28 to 30] vs. 28.00±2.17, 28 [27 to 29] mm Hg; P<0.001). Peak airway pressure (17.25±1.97, 17 [16 to 18.5] vs. 15.81±2.87, 15.5 [14 to 17] mm Hg; P<0.001) and plateau airway pressure (16.06±2.30, 16 [14.5 to 17] vs. 14.19±2.82, 14 [12.5 to 16] mm Hg; P<0.001) were higher during protective ventilation. Blood pressure, heart rate, and body temperature did not differ between ventilation modes. Dural tension was "acceptable for surgery" in all cases. ICP differences between ventilation modes were not affected by ICP values under traditional ventilation (coefficient=0.067; 95% confidence interval, -0.278 to 0.144; P=0.523). Protective ventilation is a feasible alternative to traditional ventilation during elective neurosurgery.

[Analysis of compliance of 2 prevention measures for ventilator-associated pneumonia (raised head of bed and cuff pressure control)].

PubMed

del Cotillo Fuente, M; Valls Matarín, J

2014-01-01

To quantify the hours of mechanical ventilation in patients with head of bed elevation≥30°. Determining compliance of cuff measurement every 6h. Descriptive longitudinal study. Measured: time head of bed elevation≥30°, <30° and reasons for non compliance, as well as cuff control every 6h. One hundred and seventy-two records of head of bed elevation and 584 of cuff pressure. Daily average head<30° for care or procedures: 2h (1h19'). The theoretical average number of hours that patients should remain at≥30° was 21h15' (3h) and actual 14h (5h) (P<.001). Registration of cuff was 76,7%. Cuffs between 20-30cmH2O were 75.9%. The 20% of cuff pressure were measured every 6h<20cmH2O and 33.7% when the interval was higher (P=.04). A third of the day patients are<30° without justification. Cuff pressure registration and percentage of therapeutic range are high. Control every 6h decreases the cuff with pressure<20cmH2O. Copyright © 2013 Elsevier España, S.L.U. y SEEIUC. 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.

Resistive pressure of a condenser humidifier in mechanically ventilated patients.

PubMed

Manthous, C A; Schmidt, G A

1994-11-01

Heat and moisture exchangers (or "nose" humidifiers) are commonly used to aid in the humidification of inspired gases of mechanically ventilated patients. These devices add resistance to the ventilator circuit that has heretofore not been quantified in critically ill patients. Accordingly, we determined the resistive pressures associated with new and old (but < 24 hrs in the circuit) humidifiers in 23 critically ill, mechanically ventilated patients. Prospective study. Adult medical and surgical intensive care units at a university center. Twenty-three critically ill, mechanically ventilated patients using a condenser humidifier between the wye and the endotracheal tube. Peak and plateau airway pressures were determined with the humidifier in place. These measurements were repeated without the humidifier, then after insertion of a fresh humidifier into the circuit. In five patients, measurements were repeated after humidifiers had remained in place for a full 24 hrs. The new humidifiers increased the resistive pressure of the ventilator circuit by 4.8 +/- 2.6 cm H2O compared with no humidifier (p < .01) and had a mean resistance of 4.2 +/- 1.5 cm H2O/L/sec. Old humidifiers increased resistive pressure by 6.3 +/- 3.6 cm H2O compared with no humidifier (p < .01) and had a mean resistance of 5.1 +/- 1.8 cm H2O/L/sec. The resistive pressure doubled from 3.4 +/- 1.2 to 7.0 +/- 1.8 cm H2O (p < .01) in five patients in whom the humidifiers were left in the ventilator circuit for a full 24 hrs. The humidifier adds a significant resistance to the ventilator circuit which may lead to incorrect assessment of respiratory system mechanics, to inappropriate therapy (e.g., bronchodilators), or to difficulty in weaning from mechanical ventilation.

Effect of one-lung ventilation on end-tidal carbon dioxide during cardiopulmonary resuscitation in a pig model of cardiac arrest.

PubMed

Ryu, Dong Hyun; Jung, Yong Hun; Jeung, Kyung Woon; Lee, Byung Kook; Jeong, Young Won; Yun, Jong Geun; Lee, Dong Hun; Lee, Sung Min; Heo, Tag; Min, Yong Il

2018-01-01

Unrecognized endobronchial intubation frequently occurs after emergency intubation. However, no study has evaluated the effect of one-lung ventilation on end-tidal carbon dioxide (ETCO2) during cardiopulmonary resuscitation (CPR). We compared the hemodynamic parameters, blood gases, and ETCO2 during one-lung ventilation with those during conventional two-lung ventilation in a pig model of CPR, to determine the effect of the former on ETCO2. A randomized crossover study was conducted in 12 pigs intubated with double-lumen endobronchial tube to achieve lung separation. During CPR, the animals underwent three 5-min ventilation trials based on a randomized crossover design: left-lung, right-lung, or two-lung ventilation. Arterial blood gases were measured at the end of each ventilation trial. Ventilation was provided using the same tidal volume throughout the ventilation trials. Comparison using generalized linear mixed model revealed no significant group effects with respect to aortic pressure, coronary perfusion pressure, and carotid blood flow; however, significant group effect in terms of ETCO2 was found (P < 0.001). In the post hoc analyses, ETCO2 was lower during the right-lung ventilation than during the two-lung (P = 0.006) or left-lung ventilation (P < 0.001). However, no difference in ETCO2 was detected between the left-lung and two-lung ventilations. The partial pressure of arterial carbon dioxide (PaCO2), partial pressure of arterial oxygen (PaO2), and oxygen saturation (SaO2) differed among the three types of ventilation (P = 0.003, P = 0.001, and P = 0.001, respectively). The post hoc analyses revealed a higher PaCO2, lower PaO2, and lower SaO2 during right-lung ventilation than during two-lung or left-lung ventilation. However, the levels of these blood gases did not differ between the left-lung and two-lung ventilations. In a pig model of CPR, ETCO2 was significantly lower during right-lung ventilation than during two-lung ventilation. However, interestingly, ETCO2 during left-lung ventilation was comparable to that during two-lung ventilation.

Hemodynamic effects of external continuous negative pressure ventilation compared with those of continuous positive pressure ventilation in dogs with acute lung injury.

PubMed

Skaburskis, M; Helal, R; Zidulka, A

1987-10-01

Patients with noncardiogenic pulmonary edema requiring ventilatory assistance are usually supported with CPPV using positive end-expiratory pressure (PEEP), but CPPV requires endotracheal intubation and may decrease cardiac output (QT). The purpose of this study was to examine thoracoabdominal continuous negative pressure ventilation (CNPV) using external negative end-expiratory pressure (NEEP). The effects on gas exchange and hemodynamics were compared with those of CPPV with PEEP, with the premise that CNPV might sustain venous return and improve QT. In 6 supine, anesthetized and paralyzed dogs with oleic-acid-induced pulmonary edema, 30 min of CNPV was alternated twice with 30 min of CPPV. Positive and negative pressure ventilation were carefully matched for fractional inspired oxygen concentration (FIO2 = 0.56), breathing frequency, and tidal volume. In addition, we matched the increase in delta FRC obtained with the constant distending pressures produced by both modes of ventilation. An average of -9 cm H2O of NEEP produced the same delta FRC as 10.8 cm H2O of PEEP. Gas exchange did not differ significantly between the 2 modes. However, QT was 15.8% higher during CNPV than during CPPV (p less than 0.02). Mixed venous oxygen saturation also improved during CNPV compared with that during CPPV (58.3 versus 54.5%, p less than 0.01). Negative pressure ventilation using NEEP may be a viable alternative to positive pressure ventilation with PEEP in the management of critically ill patients with noncardiogenic pulmonary edema. It offers comparable improvement in gas exchange with the advantages of less cardiac depression and the possible avoidance of endotracheal intubation.

Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients (PROBESE): study protocol for a randomized controlled trial.

PubMed

Bluth, T; Teichmann, R; Kiss, T; Bobek, I; Canet, J; Cinnella, G; De Baerdemaeker, L; Gregoretti, C; Hedenstierna, G; Hemmes, S N; Hiesmayr, M; Hollmann, M W; Jaber, S; Laffey, J G; Licker, M J; Markstaller, K; Matot, I; Müller, G; Mills, G H; Mulier, J P; Putensen, C; Rossaint, R; Schmitt, J; Senturk, M; Serpa Neto, A; Severgnini, P; Sprung, J; Vidal Melo, M F; Wrigge, H; Schultz, M J; Pelosi, P; Gama de Abreu, M

2017-04-28

Postoperative pulmonary complications (PPCs) increase the morbidity and mortality of surgery in obese patients. High levels of positive end-expiratory pressure (PEEP) with lung recruitment maneuvers may improve intraoperative respiratory function, but they can also compromise hemodynamics, and the effects on PPCs are uncertain. We hypothesized that intraoperative mechanical ventilation using high PEEP with periodic recruitment maneuvers, as compared with low PEEP without recruitment maneuvers, prevents PPCs in obese patients. The PRotective Ventilation with Higher versus Lower PEEP during General Anesthesia for Surgery in OBESE Patients (PROBESE) study is a multicenter, two-arm, international randomized controlled trial. In total, 2013 obese patients with body mass index ≥35 kg/m 2 scheduled for at least 2 h of surgery under general anesthesia and at intermediate to high risk for PPCs will be included. Patients are ventilated intraoperatively with a low tidal volume of 7 ml/kg (predicted body weight) and randomly assigned to PEEP of 12 cmH 2 O with lung recruitment maneuvers (high PEEP) or PEEP of 4 cmH 2 O without recruitment maneuvers (low PEEP). The occurrence of PPCs will be recorded as collapsed composite of single adverse pulmonary events and represents the primary endpoint. To our knowledge, the PROBESE trial is the first multicenter, international randomized controlled trial to compare the effects of two different levels of intraoperative PEEP during protective low tidal volume ventilation on PPCs in obese patients. The results of the PROBESE trial will support anesthesiologists in their decision to choose a certain PEEP level during general anesthesia for surgery in obese patients in an attempt to prevent PPCs. ClinicalTrials.gov identifier: NCT02148692. Registered on 23 May 2014; last updated 7 June 2016.

Use of volume-targeted non-invasive bilevel positive airway pressure ventilation in a patient with amyotrophic lateral sclerosis*,**

PubMed Central

Diaz-Abad, Montserrat; Brown, John Edward

2014-01-01

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease in which most patients die of respiratory failure. Although volume-targeted non-invasive bilevel positive airway pressure (BPAP) ventilation has been studied in patients with chronic respiratory failure of various etiologies, its use in ALS has not been reported. We present the case of a 66-year-old woman with ALS and respiratory failure treated with volume-targeted BPAP ventilation for 15 weeks. Weekly data downloads showed that disease progression was associated with increased respiratory muscle weakness, decreased spontaneous breathing, and increased use of non-invasive positive pressure ventilation, whereas tidal volume and minute ventilation remained relatively constant. PMID:25210968

Bipolar sealing of lung parenchyma: tests in an ex vivo model.

PubMed

Kirschbaum, A; Clemens, A; Steinfeldt, T; Pehl, A; Meyer, C; Bartsch, D K

2015-01-01

Almost every pulmonary lobe resection requires cutting the lung parenchyma in the area of a lung fissure. A monopolar cutter or stapler is often used for this purpose. The seal should be absolutely airtight to prevent post-operative pulmonary fistulas. In the present study, the bipolar sealing technique was evaluated regarding air tightness of the seals during normal ventilation and its burst pressure in an ex vivo animal model. The investigations were carried out on paracardial lung lobes obtained from heart-lung preparations taken from freshly killed pigs at a slaughter house. In the laboratory, each individual lobe was perfused with Ringer's solution at body temperature and protectively ventilated through a tube (frequency: 20 1/min, p insp = 20 mbar, PEEP +5 mbar). Non-anatomic resection was carried out in the periphery of the lung lobe. The two control groups (12 lobes per group; Group 1-stapler, Group 2-parenchyma suture) were compared to three groups in which different bipolar sealing instruments were used. They were Group 3-MARSEAL(®) 10 mm (KLS Martin, Tuttlingen); Group 4-MARSEAL(®) 5 mm; and Group 5-MARCLAMP(®) (KLS Martin, Tuttlingen). The SealSafe(®) G3 electric current was used in all cases. Ventilation was continued for 20 min following parenchymal resection. Parenchymal sealing was then judged visually in a water bath and given a score (0-3). Burst pressure (mbar) was measured by increasing the inspiration pressure stepwise. Group mean values were compared (nonparametric Mann-Whitney U test, p < 0.005). Parenchymal seals were airtight under ventilation throughout the observation period in all groups. Mean burst pressures were as follows: Group 1: 47.1 ± 6.2 mbar; Group 2: 32.9 ± 3.9 mbar; Group 3: 38.8 ± 2.2 mbar; Group 4: 25.0 ± 6.4 mbar; and Group 5: 32.9 ± 5.8 mbar. Group 1, the stapler group, thus exhibited the highest burst pressures. Burst pressures for Group 3 were significantly greater than those for Group 2 (p < 0.006). Burst pressures for groups 2 and 5 were similar (p = 0.97). However, the burst pressures for Group 4 were significantly lower than those for Group 2 (p < 0.001). MARSEAL(®) 10 mm and MARCLAMP(®) achieved adequate burst pressures compared to the two control groups and thus might be suitable for clinical use.

Moderately high frequency ventilation with a conventional ventilator allows reduction of tidal volume without increasing mean airway pressure.

PubMed

Cordioli, Ricardo Luiz; Park, Marcelo; Costa, Eduardo Leite Vieira; Gomes, Susimeire; Brochard, Laurent; Amato, Marcelo Britto Passos; Azevedo, Luciano Cesar Pontes

2014-12-01

The aim of this study was to explore if positive-pressure ventilation delivered by a conventional ICU ventilator at a moderately high frequency (HFPPV) allows a safe reduction of tidal volume (V T) below 6 mL/kg in a porcine model of severe acute respiratory distress syndrome (ARDS) and at a lower mean airway pressure than high-frequency oscillatory ventilation (HFOV). This is a prospective study. In eight pigs (median weight 34 [29,36] kg), ARDS was induced by pulmonary lavage and injurious ventilation. The animals were ventilated with a randomized sequence of respiratory rates: 30, 60, 90, 120, 150, followed by HFOV at 5 Hz. At each step, V T was adjusted to allow partial pressure of arterial carbon dioxide (PaCO2) to stabilize between 57 and 63 mmHg. Data are shown as median [P25th,P75th]. After lung injury, the PaO2/FiO2 (P/F) ratio was 92 [63,118] mmHg, pulmonary shunt 26 [17,31]%, and static compliance 11 [8,14] mL/cmH2O. Positive end-expiratory pressure (PEEP) was 14 [10,17] cmH2O. At 30 breaths/min, V T was higher than 6 (7.5 [6.8,10.2]) mL/kg, but at all higher frequencies, V T could be reduced and PaCO2 maintained, leading to reductions in plateau pressures and driving pressures. For frequencies of 60 to 150/min, V T progressively fell from 5.2 [5.1,5.9] to 3.8 [3.7,4.2] mL/kg (p < 0.001). There were no detrimental effects in terms of lung mechanics, auto-PEEP generation, hemodynamics, or gas exchange. Mean airway pressure was maintained constant and was increased only during HFOV. During protective mechanical ventilation, HFPPV delivered by a conventional ventilator in a severe ARDS swine model safely allows further tidal volume reductions. This strategy also allowed decreasing airway pressures while maintaining stable PaCO2 levels.

Transtracheal ventilation with a novel ejector-based device (Ventrain) in open, partly obstructed, or totally closed upper airways in pigs.

PubMed

Paxian, M; Preussler, N P; Reinz, T; Schlueter, A; Gottschall, R

2015-08-01

Transtracheal access and subsequent jet ventilation are among the last options in a 'cannot intubate-cannot oxygenate' scenario. These interventions may lead to hypercapnia, barotrauma, and haemodynamic failure in the event of an obstructed upper airway. The aim of the present study was to evaluate the efficacy and the haemodynamic effects of the Ventrain, a manually operated ventilation device that provides expiratory ventilation assistance. Transtracheal ventilation was carried out with the Ventrain in different airway scenarios in live pigs, and its performance was compared with a conventional jet ventilator. Pigs with open, partly obstructed, or completely closed upper airways were transtracheally ventilated either with the Ventrain or by conventional jet ventilation. Airway pressures, haemodynamic parameters, and blood gases obtained in the different settings were compared. Mean (SD) alveolar minute ventilation as reflected by arterial partial pressure of CO2 was superior with the Ventrain in partly obstructed airways after 6 min in comparison with traditional manual jet ventilation [4.7 (0.19) compared with 7.1 (0.37) kPa], and this was also the case in all simulated airway conditions. At the same time, peak airway pressures were significantly lower and haemodynamic parameters were altered to a lesser extent with the Ventrain. The results of this study suggest that the Ventrain device can ensure sufficient oxygenation and ventilation through a small-bore transtracheal catheter when the airway is open, partly obstructed, or completely closed. Minute ventilation and avoidance of high airway pressures were superior in comparison with traditional hand-triggered jet ventilation, particularly in the event of complete upper airway obstruction. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

[Spontaneous positive end-expiratory pressure ventilation in elderly patients with cardiogenic pulmonary edema. Assessment in an emergency admissions unit].

PubMed

L'Her, E; Duquesne, F; Paris, A; Mouline, J; Renault, A; Garo, B; Boles, J M

1998-06-20

Intubation and ventilatory assistance are often required in patients presenting severe hypoxemic respiratory distress, but may be contraindicated in elderly subjects due to an underlying condition. The aim of this study was to assess the feasibility, acceptability and contribution of early assistance with spontaneous positive end-expiratory pressure ventilation for elderly subjects admitted to an emergency unit for acute respiratory distress due to cardiogenic pulmonary edema. In our emergency admission unit, all patients with life-threatening hypoxemic respiratory distress are initially assisted with noninvasive spontaneous positive end-expiratory pressure ventilation using a standardized commercial device. We retrospectively analyzed the the files of all patients aged over 70 years who were treated with this standard protocol for cardiogenic pulmonary edema from April 1996 through September 1997. During the study period, 36 patients aged over 70 years required ventilatory assistance according to the standard protocol. Intubation was not reasonable in most of the patients (n = 30). After 1 hour of ventilation, none of the patients developed clinical signs of life-threatening distress. Blood gases demonstrated improved oxygenation (AEPO2 = +184.9 +/- 105.4 mmHg; p < 0.000001). Thirty-two patients were considered to be cured (88.9%) and were discharged; the cardiovascular condition was fatal in 4 patients (11.1%). The rapid improvement in clinical signs and blood gases as well as the final outcome suggests that early assistance with spontaneous positive end-expiratory pressure ventilation is warranted at admission for elderly patients with respiratory distress due to cardiogenic pulmonary edema. Compared with a control group of hospitalized patients cared for during the preceding year and who were not treated with the standard protocol, we also demonstrated a clear improvement in mortality (11% versus 20%).

FLOW-i ventilator performance in the presence of a circle system leak.

PubMed

Lucangelo, Umberto; Ajčević, Miloš; Accardo, Agostino; Borelli, Massimo; Peratoner, Alberto; Comuzzi, Lucia; Zin, Walter A

2017-04-01

Recently, the FLOW-i anaesthesia ventilator was developed based on the SERVO-i intensive care ventilator. The aim of this study was to test the FLOW-i's tidal volume delivery in the presence of a leak in the breathing circuit. We ventilated a test lung model in volume-, pressure-, and pressure-regulated volume-controlled modes (VC, PC, and PRVC, respectively) with a FLOW-i. First, the circuit remained airtight and the ventilator was tested with fresh gas flows of 6, 1, and 0.3 L/min in VC, PC, and PRVC modes and facing 4 combinations of different resistive and elastic loads. Second, a fixed leak in the breathing circuit was introduced and the measurements repeated. In the airtight system, FLOW-i maintained tidal volume (VT) and circuit pressure at approximately the set values, independently of respiratory mode, load, or fresh gas flow. In the leaking circuit, set VT = 500 mL, FLOW-i delivered higher VTs in PC (about 460 mL) than in VC and PRVC, where VTs were substantially less than 500 mL. Interestingly, VT did not differ appreciably from 6 to 0.3 L/min of fresh air flow among the 3 ventilatory modes. In the absence of leakage, peak inspiratory pressures were similar, while they were 35-45 % smaller in PRVC and VC than in PC mode in the presence of leaks. In conclusion, FLOW-i maintained VT (down to fresh gas flows of 0.3 L/min) to 90 % of its preset value in PC mode, which was 4-5 times greater than in VC or PRVC modes.

Flow dynamics in pediatric rigid bronchoscopes using computer-aided design modeling software.

PubMed

Barneck, Mitchell D; Webb, J Taylor; Robinson, Ryan E; Grimmer, J Fredrik

2016-08-01

Observed complications during rigid bronchoscopy, including hypercarbia and hypoxemia, prompted us to assess how well rigid bronchoscopes serve as an airway device. We performed computer-aided design flow analysis of pediatric rigid bronchoscopes to gain insight into flow dynamics. We made accurate three-dimensional computer models of pediatric rigid bronchoscopes and endotracheal tubes. SOLIDWORKS (Dassault Systemes, Vélizy-Villacoublay, France) flow analysis software was used to analyze fluid dynamics during pressure-controlled and volume-controlled ventilation. Flow analysis was performed on rigid bronchoscopes and similar outer diameter endotracheal tubes comparing resistance, flow, and turbulence during two ventilation modalities and in common surgical scenarios. Increased turbulent flow was observed in bronchoscopes compared to more laminar flow in endotracheal tubes of similar outer diameter. Flow analysis displayed higher resistances in all pediatric bronchoscope sizes except one (3.0 bronchoscope) compared to similar-sized endotracheal tubes. Loss of adequate ventilation was observed if the bronchoscope was not assembled correctly or if increased peak inspiratory pressures were needed. Anesthesia flow to the patient was reduced by 63% during telescope insertion. Flow analysis illustrates increased turbulent flow and increased airflow resistance in all but one size of pediatric bronchoscopes compared to endotracheal tubes. This increased turbulence and resistance, along with the unanticipated gas distal exit pattern, may contribute to the documented hypercarbia and hypoxemia during procedures. These findings may explain why hypoxemia and hypercarbia are commonly observed during rigid bronchoscopy, especially when positive pressure ventilation is needed. NA Laryngoscope, 126:1940-1945, 2016. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

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.

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.

Carbon dioxide rebreathing during non-invasive ventilation delivered by helmet: a bench study.

PubMed

Mojoli, Francesco; Iotti, Giorgio A; Gerletti, Maddalena; Lucarini, Carlo; Braschi, Antonio

2008-08-01

To define how to monitor and limit CO(2) rebreathing during helmet ventilation. Physical model study. Laboratory in a university teaching hospital. We applied pressure-control ventilation to a helmet mounted on a physical model. In series 1 we increased CO(2) production (V'CO(2)) from 100 to 550 ml/min and compared mean inhaled CO(2) (iCO(2),mean) with end-inspiratory CO(2) at airway opening (eiCO(2)), end-tidal CO(2) at Y-piece (yCO(2)) and mean CO(2) inside the helmet (hCO(2)). In series 2 we observed, at constant V'CO(2), effects on CO(2) rebreathing of inspiratory pressure, respiratory mechanics, the inflation of cushions inside the helmet and the addition of a flow-by. In series 1, iCO(2),mean linearly related to V'CO(2). The best estimate of CO(2) rebreathing was provided by hCO(2): differences between iCO(2),mean and hCO(2), yCO(2) and eiCO(2) were 0.0+/-0.1, 0.4+/-0.2 and -1.3+/-0.5%. In series 2, hCO(2) inversely related to the total ventilation (MVtotal) delivered to the helmet-patient unit. The increase in inspiratory pressure significantly increased MVtotal and lowered hCO(2). The low lung compliance halved the patient:helmet ventilation ratio but led to minor changes in MVtotal and hCO(2). Cushion inflation, although it decreased the helmet's internal volume by 33%, did not affect rebreathing. A 8-l/min flow-by effectively decreased hCO(2). During helmet ventilation, rebreathing can be assessed by measuring hCO(2) or yCO(2), but not eiCO(2). It is directly related to V'CO(2), inversely related to MVtotal and can be lowered by increasing inspiratory pressure or adding a flow-by.

Ventilation Increases with Lower Extremity Venous Occlusion in Young Adults

PubMed Central

Keller-Ross, Manda L.; Cowl, Andrielle L.; Cross, Troy; Johnson, Bruce D.; Olson, Thomas P.

2015-01-01

Introduction Venous distention via sub-systolic occlusion of the lower limbs may augment ventilation via stimulation of group III/IV afferent neurons. Purpose The purpose of this study was to examine the ventilatory response to graded lower extremity venous occlusion during exercise in healthy adults. Methods Nineteen adults (9 men, 25±5 yr) completed two visits. Visit 1: a maximal cycle ergometry exercise test. Visit 2 included a 30% peak workload cycle exercise with randomized inflations of bilateral thigh pressure tourniquets to 20, 40, 60, 80, 100 mmHg for 2 min each, separated by 2 min of deflation. Three min of cycling occurred prior to cuffing (CTL). Expired minute ventilation (VE), whole body gas exchange, rating of perceived exertion and dyspnea were measured during each session. Results VE increased significantly from the control condition (exercise only, control, CTL) to each occlusion pressure (p<0.05) with the greatest increase at 100 mmHg (CTL to 100 mmHg: 31.5±6.6 to 40.1±10.7 L/min). Respiratory rate (RR) increased as well (CTL to 100 mmHg: 24.8±6.0 to 30.9±11.5 breaths/min, p<0.05, condition effect) with no change in tidal volume (p>0.05). Tidal volume to inspiratory time (VT/TI) increased significantly from the CTL condition to each occlusion pressure (CTL to 100 mmHg: 1.5±0.3 to 1.8±0.4 L/min, p<0.05, all pressures). Dyspnea and RPE increased with all occlusion pressures from CTL exercise (p<0.05, all pressures). Conclusion Our findings suggest that mild-to-moderate venous occlusion of the lower extremity evokes a tachypneic breathing pattern which, in turn, augments VE and perceived breathing effort during exercise. PMID:26484951

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study.

PubMed

Nakamura, Maria Aparecida Miyuki; Costa, Eduardo Leite Vieira; Carvalho, Carlos Roberto Ribeiro; Tucci, Mauro Roberto

2014-01-01

Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM.

Prone positioning in hypoxemic respiratory failure: meta-analysis of randomized controlled trials.

PubMed

Kopterides, Petros; Siempos, Ilias I; Armaganidis, Apostolos

2009-03-01

Prone positioning is used to improve oxygenation in patients with hypoxemic respiratory failure (HRF). However, its role in clinical practice is not yet clearly defined. The aim of this meta-analysis was to assess the effect of prone positioning on relevant clinical outcomes, such as intensive care unit (ICU) and hospital mortality, days of mechanical ventilation, length of stay, incidence of ventilator-associated pneumonia (VAP) and pneumothorax, and associated complications. We used literature search of MEDLINE, Current Contents, and Cochrane Central Register of Controlled Trials. We focused only on randomized controlled trials reporting clinical outcomes in adult patients with HRF. Four trials met our inclusion criteria, including 662 patients randomized to prone ventilation and 609 patients to supine ventilation. The pooled odds ratio (OR) for the ICU mortality in the intention-to-treat analysis was 0.97 (95% confidence interval [CI], 0.77-1.22), for the comparison between prone and supine ventilated patients. Interestingly, the pooled OR for the ICU mortality in the selected group of the more severely ill patients favored prone positioning (OR, 0.34; 95% CI, 0.18-0.66). The duration of mechanical ventilation and the incidence of pneumothorax were not different between the 2 groups. The incidence of VAP was lower but not statistically significant in patients treated with prone positioning (OR, 0.81; 95% CI, 0.61-1.10). However, prone positioning was associated with a higher risk of pressure sores (OR, 1.49; 95% CI, 1.17-1.89) and a trend for more complications related to the endotracheal tube (OR, 1.30; 95% CI, 0.94-1.80). Despite the inherent limitations of the meta-analytic approach, it seems that prone positioning has no discernible effect on mortality in patients with HRF. It may decrease the incidence of VAP at the expense of more pressure sores and complications related to the endotracheal tube. However, a subgroup of the most severely ill patients may benefit most from this intervention.

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.

Pleth variability index and respiratory system compliance to direct PEEP settings in mechanically ventilated patients, an exploratory study.

PubMed

Zhou, Jing; Han, Yi

2016-01-01

To analyze the ability of pleth variability index (PVI) and respiratory system compliance (RSC) on evaluating the hemodynamic and respiratory effects of positive end expiratory pressure (PEEP), then to direct PEEP settings in mechanically ventilated critical patients. We studied 22 mechanically ventilated critical patients in the intensive care unit. Patients were monitored with classical monitor and a pulse co-oximeter, with pulse sensors attached to patients' index fingers. Hemodynamic data [heart rate (HR), perfusion index (PI), PVI, central venous pressure (CVP), mean arterial pressure (MAP), peripheral blood oxygen saturation (SPO2), peripheral blood oxygen content (SPOC) and peripheral blood hemoglobin (SPHB)] as well as the respiratory data [respiratory rate (RR), tidal volume (VT), RSC and controlled airway pressure] were recorded for 15 min each at 3 different levels of PEEP (0, 5 and 10 cmH2O). Different levels of PEEP (0, 5 and 10 cmH2O) had no obvious effect on RR, HR, MAP, SPO2 and SPOC. However, 10 cmH2O PEEP induced significant hemodynamic disturbances, including decreases of PI, and increases of both PVI and CVP. Meanwhile, 5 cmH2O PEEP induced no significant changes on hemodynamics such as CVP, PI and PVI, but improved the RSC. RSC and PVI may be useful in detecting the hemodynamic and respiratory effects of PEEP, thus may help clinicians individualize PEEP settings in mechanically ventilated patients.

The use of intermittent positive pressure ventilation to differentiate pneumonia from atelectasis during anesthesia in a red panda (Ailurus fulgens).

PubMed

Phair, Kristen; West, Gary; Biller, David

2010-12-01

Radiography is a valuable tool for assessment of pulmonary disease. Specifically, radiographs utilizing positive pressure ventilation can distinguish between anesthesia-induced atelectasis and pulmonary disease when survey radiographs are ambiguous. Positive pressure ventilation can be used to radiographically prove or disprove pulmonary disease. This is of particular clinical importance when working with exotic, zoo, or wildlife species because the majority of these patients require general anesthesia to perform physical examinations and diagnostics such as radiography safely and efficiently. This report is a case example of pulmonary disease in a red panda (Ailurus fulgens) and demonstrates how positive pressure ventilation verified both the presence of pulmonary disease and the eventual resolution of the disease. Anesthetized patients on gas anesthesia will rapidly become atelectic. Through the use of positive pressure ventilation, anesthesia-induced atelectasis and true pulmonary disease can readily be distinguished. This is a technique that should not be overlooked when performing thoracic radiography in zoo species.

Low-Tidal-Volume Ventilation in the Acute Respiratory Distress Syndrome

PubMed Central

Malhotra, Atul

2008-01-01

A 55-year-old man who is 178 cm tall and weighs 95 kg is hospitalized with community-acquired pneumonia and progressively severe dyspnea. His arterial oxygen saturation while breathing 100% oxygen through a face mask is 76%; a chest radiograph shows diffuse alveolar infiltrates with air bronchograms. He is intubated and receives mechanical ventilation; ventilator settings include a tidal volume of 1000 ml, a positive end-expiratory pressure (PEEP) of 5 cm of water, and a fraction of inspired oxygen (FiO2) of 0.8. With these settings, peak airway pressure is 50 to 60 cm of water, plateau airway pressure is 38 cm of water, partial pressure of arterial oxygen is 120 mm Hg, partial pressure of carbon dioxide is 37 mm Hg, and arterial blood pH is 7.47. The diagnosis of the acute respiratory distress syndrome (ARDS) is made. An intensive care specialist evaluates the patient and recommends changing the current ventilator settings and implementing a low-tidal-volume ventilation strategy. PMID:17855672

The Effect of Listening to Holy Quran Recitation on Weaning Patients Receiving Mechanical Ventilation in the Intensive Care Unit: A Pilot Study.

PubMed

Yadak, Mohammad; Ansari, Khalid Aziz; Qutub, Hatem; Al-Otaibi, Hajed; Al-Omar, Omar; Al-Onizi, Nawal; Farooqi, Faraz Ahmed

2017-09-30

Mechanical ventilation (MV) causes high level of stress in hospitalized patients. Weaning is the gradual process of decreasing ventilator support that in turn lead to termination of MV and increased respiratory effort, which may exacerbate symptoms and prolong MV. This study aimed to investigate the effect of listening to Holy Quran recitation (HQR) as a non-pharmacological intervention in patients during weaning from mechanical ventilation. This is a randomized controlled trial in which 55 patients admitted in the intensive care unit (ICU) and on mechanical ventilation were recruited. Patients were divided into experimental (case) and control group. In the experimental group, patients received 30 min of HQR, whereas in the control group, patients had 30 min of rest in bed before the start of the weaning. The physiological and/or clinical parameters of weaning were recorded. These parameters include rapid shallow breathing index, respiratory rate, heart rate, oxygen saturation, exhaled carbon dioxide, and blood pressure. The baseline demographic data for groups were presented in tables. The mean age was 54 ± 0.5 years for the experimental and 56.4 ± 18.5 years for the control groups. The physiological and clinical parameters were compared between case and control and found no significant difference. The preliminary findings of this pilot study suggest that there is no negative effect of HQR on weaning patients from mechanical ventilation in the ICU. The results also outline and explorthe possible utility of HQR further in ICU patients as an intervention in weaning patients off from ventilator in the ICU. Although there remains much to be done, our work generates important findings in the field of critical care management.

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.

An in vitro evaluation of the influence of neonatal endotracheal tube diameter and length on the work of breathing.

PubMed

Miyake, Fuyu; Suga, Rika; Akiyama, Takahiro; Namba, Fumihiko

2018-04-06

Neonates, particularly premature babies, are often managed with endotracheal intubation and subsequent mechanical ventilation to maintain adequate pulmonary gas exchange. There is no consensus on the standard length of endotracheal tube. Although a short tube reduces resistance and respiratory dead space, it is believed to increase the risk of accidental extubation. There are not entirely coherent data regarding the effect of endotracheal tube length on work of breathing in infants. The aim of this study was to evaluate the impact of neonatal endotracheal tube diameter and length on the work of breathing using an infant in vitro lung model. We assessed the work of breathing index and mechanical ventilation settings with various endotracheal tube diameters and lengths using the JTR100 in vitro infant lung model. The basic parameters of the model were breathing frequency of 20 per minutes, inspiratory-expiratory ratio of 1:3, and positive end-expiratory pressure of 5 cmH 2 O. In addition, the diaphragm driving pressure to maintain the set tidal volume was measured as the work of breathing index. The JTR100 was connected to the Babylog 8000plus through the endotracheal tube. Finally, we monitored the peak inspiratory pressure generated during assist-control volume guarantee mode with a targeted tidal volume of 10-30 mL. The diaphragm driving pressure using a 2.0-mm inner diameter tube was twice as high as that using a 4.0-mm inner diameter tube. To maintain the targeted tidal volume, a shorter tube reduced both the diaphragm driving pressure and ventilator-generated peak inspiratory pressure. The difference in the generated peak inspiratory pressure between the shortest and longest tubes was 5 cmH 2 O. In our infant lung model, a shorter tube resulted in a lower work of breathing and lower ventilator-generated peak inspiratory pressure. © 2018 John Wiley & Sons Ltd.

Effect of leak and breathing pattern on the accuracy of tidal volume estimation by commercial home ventilators: a bench study.

PubMed

Luján, Manel; Sogo, Ana; Pomares, Xavier; Monsó, Eduard; Sales, Bernat; Blanch, Lluís

2013-05-01

New home ventilators are able to provide clinicians data of interest through built-in software. Monitoring of tidal volume (VT) is a key point in the assessment of the efficacy of home mechanical ventilation. To assess the reliability of the VT provided by 5 ventilators in a bench test. Five commercial ventilators from 4 different manufacturers were tested in pressure support mode with the help of a breathing simulator under different conditions of mechanical respiratory pattern, inflation pressure, and intentional leakage. Values provided by the built-in software of each ventilator were compared breath to breath with the VT monitored through an external pneumotachograph. Ten breaths for each condition were compared for every tested situation. All tested ventilators underestimated VT (ranges of -21.7 mL to -83.5 mL, which corresponded to -3.6% to -14.7% of the externally measured VT). A direct relationship between leak and underestimation was found in 4 ventilators, with higher underestimations of the VT when the leakage increased, ranging between -2.27% and -5.42% for each 10 L/min increase in the leakage. A ventilator that included an algorithm that computes the pressure loss through the tube as a function of the flow exiting the ventilator had the minimal effect of leaks on the estimation of VT (0.3%). In 3 ventilators the underestimation was also influenced by mechanical pattern (lower underestimation with restrictive, and higher with obstructive). The inclusion of algorithms that calculate the pressure loss as a function of the flow exiting the ventilator in commercial models may increase the reliability of VT estimation.

Are we fully utilizing the functionalities of modern operating room ventilators?

PubMed

Liu, Shujie; Kacmarek, Robert M; Oto, Jun

2017-12-01

The modern operating room ventilators have become very sophisticated and many of their features are comparable with those of an ICU ventilator. To fully utilize the functionality of modern operating room ventilators, it is important for clinicians to understand in depth the working principle of these ventilators and their functionalities. Piston ventilators have the advantages of delivering accurate tidal volume and certain flow compensation functions. Turbine ventilators have great ability of flow compensation. Ventilation modes are mainly volume-based or pressure-based. Pressure-based ventilation modes provide better leak compensation than volume-based. The integration of advanced flow generation systems and ventilation modes of the modern operating room ventilators enables clinicians to provide both invasive and noninvasive ventilation in perioperative settings. Ventilator waveforms can be used for intraoperative neuromonitoring during cervical spine surgery. The increase in number of new features of modern operating room ventilators clearly creates the opportunity for clinicians to optimize ventilatory care. However, improving the quality of ventilator care relies on a complete understanding and correct use of these new features. VIDEO ABSTRACT: http://links.lww.com/COAN/A47.

Nocturnal mechanical ventilation for chronic hypoventilation in patients with neuromuscular and chest wall disorders.

PubMed

Annane, Djillali; Orlikowski, David; Chevret, Sylvie

2014-12-13

Chronic alveolar hypoventilation is a common complication of many neuromuscular and chest wall disorders. Long-term nocturnal mechanical ventilation is commonly used to treat it. This is a 2014 update of a review first published in 2000 and previously updated in 2007. To examine the effects on mortality of nocturnal mechanical ventilation in people with neuromuscular or chest wall disorders. Subsidiary endpoints were to examine the effects of respiratory assistance on improvement of chronic hypoventilation, sleep quality, hospital admissions and quality of life. We searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL, MEDLINE and EMBASE on 10 June 2014. We contacted authors of identified trials and other experts in the field. We searched for quasi-randomised or randomised controlled trials of participants of all ages with neuromuscular or chest wall disorder-related stable chronic hypoventilation of all degrees of severity, receiving any type and any mode of long-term nocturnal mechanical ventilation. The primary outcome measure was one-year mortality and secondary outcomes were unplanned hospital admission, short-term and long-term reversal of hypoventilation-related clinical symptoms and daytime hypercapnia, improvement of lung function and sleep breathing disorders. We used standard Cochrane methodology to select studies, extract data and assess the risk of bias in included studies. The 10 eligible trials included a total of 173 participants. Roughly half of the trials were at low risk of selection, attrition or reporting bias, and almost all were at high risk of performance and detection bias. Four trials reported mortality data in the long term. The pooled risk ratio (RR) of dying was 0.62 (95% confidence interval (CI) 0.42 to 0.91, P value = 0.01) in favour of nocturnal mechanical ventilation compared to spontaneous breathing. There was considerable and significant heterogeneity between the trials, possibly related to differences between the study populations. Information on unplanned hospitalisation was available from two studies. The corresponding pooled RR was 0.25 (95% CI 0.08 to 0.82, P value = 0.02) in favour of nocturnal mechanical ventilation. For most of the outcome measures there was no significant long-term difference between nocturnal mechanical ventilation and no ventilation. Most of the secondary outcomes were not assessed in the eligible trials. Three out of the 10 trials, accounting for 39 participants, two with a cross-over design and one with two parallel groups, compared volume- and pressure-cycled non-invasive mechanical ventilation in the short term. From the only trial (16 participants) on parallel groups, there was no difference in mortality (one death in each arm) between volume- and pressure-cycled mechanical ventilation. Data from the two cross-over trials suggested that compared with pressure-cycled ventilation, volume-cycled ventilation was associated with less sleep time spent with an arterial oxygen saturation below 90% (mean difference (MD) 6.83 minutes, 95% CI 4.68 to 8.98, P value = 0.00001) and a lower apnoea-hypopnoea (per sleep hour) index (MD -0.65, 95% CI -0.84 to -0.46, P value = 0.00001). We found no study that compared invasive and non-invasive mechanical ventilation or intermittent positive pressure versus negative pressure ventilation. Current evidence about the therapeutic benefit of mechanical ventilation is of very low quality, but is consistent, suggesting alleviation of the symptoms of chronic hypoventilation in the short term. In four small studies, survival was prolonged and unplanned hospitalisation was reduced, mainly in participants with motor neuron diseases. With the exception of motor neuron disease and Duchenne muscular dystrophy, for which the natural history supports the survival benefit of mechanical ventilation against no ventilation, further larger randomised trials should assess the long-term benefit of different types and modes of nocturnal mechanical ventilation on quality of life, morbidity and mortality, and its cost-benefit ratio in neuromuscular and chest wall diseases.

High pressure versus high intensity noninvasive ventilation in stable hypercapnic chronic obstructive pulmonary disease: a randomized crossover trial.

PubMed

Murphy, Patrick B; Brignall, Kate; Moxham, John; Polkey, Michael I; Davidson, A Craig; Hart, Nicholas

2012-01-01

High-intensity (high-pressure and high backup rate) noninvasive ventilation has recently been advocated for the management of stable hypercapnic chronic obstructive pulmonary disease (COPD). However, the relative contributions of high inspiratory pressure and high backup rate to ventilator adherence and physiological outcome have not been investigated. Patients with stable hypercapnic COPD (daytime PaCO(2) > 6 kPa) and nocturnal hypoventilation were enrolled. Patients were randomly allocated to high-pressure and high backup rate (high-intensity) and high-pressure and low backup rate (high-pressure) for a 6-week period. At the end of the first treatment period, patients were switched to the alternative treatment. The primary outcome measure was mean nightly ventilator usage. Twelve patients were recruited, with seven completing the 12-week trial protocol. The mean patient age was 71 ± 8 years, with a forced expiratory volume in one second (FEV(1))/forced vital capacity (FVC) of 50% ± 13% and FEV(1) of 32% ± 12%. The baseline PaCO(2) and PaO(2) were 8.6 ± 1.7 kPa and 7.3 ± 1.4 kPa, respectively. There was no significant difference demonstrated in mean nightly ventilator usage between the high-intensity and high-pressure groups (difference of 4 minutes; 95% confidence interval -45 to 53; P = 0.9). Furthermore, there were no differences in any of the secondary endpoints, with the exception of the respiratory domain of the Severe Respiratory Insufficiency questionnaire, which was lower in the high-intensity arm than in the high-pressure arm (57 ± 11 versus 69 ± 16; P < 0.05). There was no additional benefit, in terms of night-time ventilator adherence or any of the other measured parameters, demonstrated by addition of a high backup rate to high-pressure noninvasive ventilation. These data suggest that it is the high-pressure component of the high-intensity noninvasive ventilation approach that plays the important therapeutic role in the management of hypercapnic respiratory failure in COPD patients.

Effect of varying the pressurisation rate during noninvasive pressure support ventilation.

PubMed

Prinianakis, G; Delmastro, M; Carlucci, A; Ceriana, P; Nava, S

2004-02-01

The aim of the study was to assess the effects of varying the pressurisation rate during noninvasive pressure support ventilation on patients' breathing pattern, inspiratory effort, arterial blood gases, tolerance to ventilation and amount of air leakage. A total of 15 chronic obstructive pulmonary disease patients recovering from an acute episode of hypercapnic acute respiratory failure were studied during four randomised trials with different levels of pressurisation rate. No significant changes were observed in breathing pattern and arterial blood gases between the different runs. The pressure time product of the diaphragm, an estimate of its metabolic consumption, was significantly lower with all pressurisation rates than with spontaneous breathing, but was significantly lowest with the fastest rate. However, air leak, assessed by the ratio between expired and inspired tidal volumes, increased and the patients' tolerance of ventilation, measured using a standardised scale, was significantly poorer with the fastest pressurisation rate. In chronic obstructive pulmonary disease patients recovering from an episode of acute hypercapnic respiratory failure and ventilated with noninvasive pressure support ventilation, different pressurisation rates resulted in different reductions in the pressure time product of the diaphragm; this reduction was greater with the fastest rate, but was accompanied by significant air leaks and poor tolerance.

Particulate matter in animal rooms housing mice in microisolation caging.

PubMed

Langham, Gregory L; Hoyt, Robert F; Johnson, Thomas E

2006-11-01

Reactions to allergens created by laboratory animals are among the most frequently encountered occupational illnesses associated with research animals. Personnel are exposed to these allergens through airborne particulate matter. Although the use of microisolation caging systems can reduce particulate matter concentrations in rooms housing mice, the operating parameters of ventilated caging systems vary extensively. We compared room air in mouse rooms containing 5 different types of caging: 1) individually ventilated caging under positive pressure with filtered intake air and exhaust air returned to the room (VCR+), 2) individually ventilated caging under negative pressure with exhaust air returned to the room (VCR-), 3) individually ventilated caging under positive pressure with exhaust air returned to the heating, ventilation, and air-conditioning (HVAC) system, 4) individually ventilated caging under negative pressure with exhaust air returned to the HVAC system, and 5) static microisolation cages. We found that rooms under VCR conditions had fewer large particles than did those under other conditions, but the numbers of 0.3 microm particles did not differ significantly among systems. Static, positive or negative pressure applied to caging units as well as route of air exhaust were found to have little influence on the total number of particles in the atmosphere. Therefore, considering the heat load, odor, and overall particulate concentration in the room, placing individually ventilated caging under negative pressure with exhaust air returned to the HVAC system appears to be the optimal overall choice when using microisolation housing for rodents.

Utilizing a Suited Manikin Test Apparatus and Spacesuit Ventilation Loop to Evaluate Carbon Dioxide Washout

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Conger, Bruce; Korona, Adam; Kanne, Bryan; McMillin, Summer; Norcross, Jason; Jeng, Frank; Swickrath, Mike

2014-01-01

NASA is pursuing technology development of an Advanced Extravehicular Mobility Unit (AEMU) which is an integrated assembly made up of primarily a pressure garment system and a Portable Life Support System (PLSS). The PLSS is further composed of an oxygen subsystem, a ventilation subsystem, and a thermal subsystem. One of the key functions of the ventilation system is to remove and control the carbon dioxide delivered to the crewmember. Carbon dioxide washout is the mechanism by which CO2 levels are controlled within the spacesuit helmet to limit the concentration of CO2 inhaled by the crew member. CO2 washout performance is a critical parameter needed to ensure proper and robust designs that are insensitive to human variabilities in a spacesuit. A Suited Manikin Test Apparatus (SMTA) is being developed to augment testing of the PLSS ventilation loop in order to provide a lower cost and more controlled alternative to human testing. The CO2 removal function is performed by the regenerative Rapid Cycle Amine (RCA) within the PLSS ventilation loop and its performance is evaluated within the integrated SMTA and Ventilation Loop test system. This paper will provide a detailed description of the schematics, test configurations, and hardware components of this integrated system. Results and analysis of testing performed with this integrated system will be presented within this paper.

Utilizing a Suited Manikin Test Apparatus and Space Suit Ventilation Loop to Evaluate Carbon Dioxide Washout

NASA Technical Reports Server (NTRS)

Chullen, Cinda; Conger, Bruce; Korona, Adam; Kanne, Bryan; McMillin, Summer; Paul, Thomas; Norcross, Jason; Alonso, Jesus Delgado; Swickrath, Mike

2015-01-01

NASA is pursuing technology development of an Advanced Extravehicular Mobility Unit (AEMU) which is an integrated assembly made up of primarily a pressure garment system and a portable life support subsystem (PLSS). The PLSS is further composed of an oxygen subsystem, a ventilation subsystem, and a thermal subsystem. One of the key functions of the ventilation system is to remove and control the carbon dioxide (CO2) delivered to the crewmember. Carbon dioxide washout is the mechanism by which CO2 levels are controlled within the space suit helmet to limit the concentration of CO2 inhaled by the crew member. CO2 washout performance is a critical parameter needed to ensure proper and robust designs that are insensitive to human variabilities in a space suit. A suited manikin test apparatus (SMTA) was developed to augment testing of the PLSS ventilation loop in order to provide a lower cost and more controlled alternative to human testing. The CO2 removal function is performed by the regenerative Rapid Cycle Amine (RCA) within the PLSS ventilation loop and its performance is evaluated within the integrated SMTA and Ventilation Loop test system. This paper will provide a detailed description of the schematics, test configurations, and hardware components of this integrated system. Results and analysis of testing performed with this integrated system will be presented within this paper.

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.

Influence of different interfaces on synchrony during pressure support ventilation in a pediatric setting: a bench study.

PubMed

Conti, Giorgio; Gregoretti, Cesare; Spinazzola, Giorgia; Festa, Olimpia; Ferrone, Giuliano; Cipriani, Flora; Rossi, Marco; Piastra, Marco; Costa, Roberta

2015-04-01

In adults and children, patient-ventilator synchrony is strongly dependent on both the ventilator settings and interface used in applying positive pressure to the airway. The aim of this bench study was to determine whether different interfaces and ventilator settings may influence patient-ventilator interaction in pediatric models of normal and mixed obstructive and restrictive respiratory conditions. A test lung, connected to a pediatric mannequin using different interfaces (endotracheal tube [ETT], face mask, and helmet), was ventilated in pressure support ventilation mode testing 2 ventilator settings (pressurization time [Timepress]50%/cycling-off flow threshold [Trexp]25%, Timepress80%/Trexp60%), randomly applied. The test lung was set to simulate one pediatric patient with a healthy respiratory system and another with a mixed obstructive and restricted respiratory condition, at different breathing frequencies (f) (30, 40, and 50 breaths/min). We measured inspiratory trigger delay, pressurization time, expiratory trigger delay, and time of synchrony. At each breathing frequency, the helmet showed the longest inspiratory trigger delay compared with the ETT and face mask. At f30, the ETT had a reduced Tpress. The helmet had the shortest Tpress in the simulated child with a mixed obstructive and restricted respiratory condition, at f40 during Timepress50%/Trexp25% and at f50 during Timepress80%/Trexp60%. In the simulated child with a normal respiratory condition, the ETT presented the shortest Tpress value at f50 during Timepress80%/Trexp60%. Concerning the expiratory trigger delay, the helmet showed the best interaction at f30, but the worst at f40 and at f50. The helmet showed the shortest time of synchrony during all ventilator settings. The choice of the interface can influence patient-ventilator synchrony in a pediatric model breathing at increased f, thus making it more difficult to set the ventilator, particularly during noninvasive ventilation. The helmet demonstrated the worst interaction, suggesting that the face mask should be considered as the first choice for delivering noninvasive ventilation in a pediatric model. Copyright © 2015 by Daedalus Enterprises.

What is the Optimal Strategy for Adaptive Servo-Ventilation Therapy?

PubMed

Imamura, Teruhiko; Kinugawa, Koichiro

2018-05-23

Clinical advantages in the adaptive servo-ventilation (ASV) therapy have been reported in selected heart failure patients with/without sleep-disorder breathing, whereas multicenter randomized control trials could not demonstrate such advantages. Considering this discrepancy, optimal patient selection and device setting may be a key for the successful ASV therapy. Hemodynamic and echocardiographic parameters indicating pulmonary congestion such as elevated pulmonary capillary wedge pressure were reported as predictors of good response to ASV therapy. Recently, parameters indicating right ventricular dysfunction also have been reported as good predictors. Optimal device setting with appropriate pressure setting during appropriate time may also be a key. Large-scale prospective trial with optimal patient selection and optimal device setting is warranted.

Summary of human responses to ventilation.

PubMed

Seppänen, O A; Fisk, W J

2004-01-01

It is known that ventilation is necessary to remove indoor-generated pollutants from indoor air or dilute their concentration to acceptable levels. But as the limit values of all pollutants are not known the exact determination of required ventilation rates based on pollutant concentrations is seldom possible. The selection of ventilation rates has to be based also on epidemiological research, laboratory and field experiments and experience. The existing literature indicates that ventilation has a significant impact on several important human outcomes including: (1) communicable respiratory illnesses; (2) sick building syndrome symptoms; (3) task performance and productivity, and (4) perceived air quality (PAQ) among occupants or sensory panels (5) respiratory allergies and asthma. In many studies, prevalence of sick building syndrome symptoms has also been associated with characteristics of HVAC-systems. Often the prevalence of SBS symptoms is higher in air-conditioned buildings than in naturally ventilated buildings. The evidence suggests that better hygiene, commissioning, operation and maintenance of air handling systems may be particularly important for reducing the negative effects of HVAC systems. Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated. Ventilation may bring indoors harmful substances or deteriorate indoor environment. Ventilation interacts also with the building envelope and may deteriorate the structures of the building. Ventilation changes the pressure differences across the structures of building and may cause or prevent infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. The paper summarises the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus is on office-type working environment and residential buildings. The review shows that ventilation has various positive impacts on health and productivity of building occupants. Ventilation reduces the prevalence of airborne infectious diseases and thus the number of sick leave days. In office environment a ventilation rate up to 20-25 L/s per person seem to decrease the prevalence of SBS-symptoms. Air conditioning systems may increase the prevalence of SBS-symptoms relative to natural ventilation if not clean. In residential buildings the air change rate in cold climates should not be below app. 0.5 ach. Ventilation systems may cause pressure differences over the building envelope and bring harmful pollutants indoors.

Real-time video communication improves provider performance in a simulated neonatal resuscitation.

PubMed

Fang, Jennifer L; Carey, William A; Lang, Tara R; Lohse, Christine M; Colby, Christopher E

2014-11-01

To determine if a real-time audiovisual link with a neonatologist, termed video-assisted resuscitation or VAR, improves provider performance during a simulated neonatal resuscitation scenario. Using high-fidelity simulation, 46 study participants were presented with a neonatal resuscitation scenario. The control group performed independently, while the intervention group utilized VAR. Time to effective ventilation was compared using Wilcoxon rank sum tests. Providers' use of the corrective steps for ineffective ventilation per the NRP algorithm was compared using Cochran-Armitage trend tests. The time needed to establish effective ventilation was significantly reduced in the intervention group when compared to the control group (mean time 2 min 42 s versus 4 min 11 s, p<0.001). In the setting of ineffective ventilation, only 35% of control subjects used three or more of the first five corrective steps and none of them used all five steps. Providers in the control group most frequently neglected to open the mouth and increase positive pressure. In contrast, all of those in the intervention group used all of the first five corrective steps, p<0.001. All participants in the control group decided to intubate the infant to establish effective ventilation, compared to none in the intervention group, p<0.001. Using VAR during a simulated neonatal resuscitation scenario significantly reduces the time to establish effective ventilation and improves provider adherence to NRP guidelines. This technology may be a means for regional centers to support local providers during a neonatal emergency to improve patient safety and improve neonatal outcomes. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The effect of non-invasive positive pressure ventilation (NIPPV) on cognitive function in amyotrophic lateral sclerosis (ALS): a prospective study

PubMed Central

Newsom-Davis, I; Lyall, R; Leigh, P; Moxham, J; Goldstein, L

2001-01-01

OBJECTIVES—Neuropsychological investigations have shown a degree of cognitive dysfunction in a proportion of non-demented patients with ALS. Respiratory muscle weakness in ALS can lead to nocturnal hypoventilation, resulting in sleep disturbance and daytime somnolence. Sleep deprivation of this type may cause impairments in cognitive function, but this has not been formally evaluated in ALS.
METHODS—Cognitive functioning was evaluated in nine patients with ALS with sleep disturbance caused by nocturnal hypoventilation (NIPPV group), and in a comparison group of 10 similar patients without ventilation problems (control group). The NIPPV group then started non-invasive positive pressure ventilation (NIPPV) at night. After about 6 weeks, change in cognitive function was evaluated.
RESULTS—Statistically significant improvement in scores on two of the seven cognitive tests was demonstrated in the NIPPV group postventilation, and a trend towards significant improvement was found for two further tests. Scores in the control group did not improve significantly for these four tests, although an improvement was found on one other test.
CONCLUSIONS—Nocturnal hypoventilation and sleep disturbance may cause cognitive dysfunction in ALS. These deficits may be partially improved by NIPPV over a 6 week period. This has important implications for investigations of both cognitive dysfunction in non-demented patients with ALS, and the effect of ventilation on quality of life.

 PMID:11561031

The incidence of pressure ulcer in patients on mechanical ventilation andeffects of selected risk factors on pressure ulcer development.

PubMed

Karayurt, Özgül; Akyol, Özay; Kılıçaslan, Necmiye; Akgün, Nuray; Sargın, Ümran; Kondakçı, Melike; Ekinci, Hanım; Sarı, Neslihan

2016-11-17

This study aimed to determine the incidence of pressure ulcers in patients on mechanical ventilation and selected risk factors likely to play a role in pressure ulcer development. The study included 110 patients recruited from an anesthesia critical care unit of a university hospital. Data were collected with a demographic and clinical characteristics form. The form was composed of questions about demographic characteristics and clinical features including diagnosis, duration of mechanical ventilation, general well-being, oxygenation, perfusion, and skin condition. The incidence of pressure ulcer was 15.5%. Duration of mechanical ventilation was longer and the body mass index was higher in patients developing pressure ulcers than in those without pressure ulcers. Additionally, 90.11% of patients with pressure ulcers had edema and 82.35% of patients with pressure ulcers received vasopressin. The patients with pressure ulcers had higher PH levels, lower PaO2 levels, higher PCO2 levels, lower SaO2 levels, and higher urine output. It can be recommended that nurses and other health professionals should be aware of factors playing a role in pressure ulcer development and should be able to conduct appropriate interventions to prevent pressure ulcers.

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.

Effects of expiratory ribcage compression before endotracheal suctioning on arterial blood gases in patients receiving mechanical ventilation.

PubMed

Kohan, Mahmoud; Rezaei-Adaryani, Morteza; Najaf-Yarandi, Akram; Hoseini, Fatemeh; Mohammad-Taheri, Nahid

2014-09-01

To investigate the effects of expiratory ribcage compression (ERCC) before endotracheal suctioning on the arterial blood gases (ABG) in patients receiving mechanical ventilation. Endotracheal suctioning is one of the most frequently used methods for airway clearance in patients receiving mechanical ventilation. Chest physiotherapy techniques such as ERCC before endotracheal suctioning can be used as a means to facilitate mobilizing and removing airway secretions and improving alveolar ventilation. A prospective, randomized, controlled cross-over design. A randomized controlled cross-over trial with a convenience sample of 70 mechanically ventilated patients was conducted from 2006 to 2007. The patients received endotracheal suctioning with (experiment-period) or without (control-period) an antecedent 5-min expiratory ribcage. All the patients experienced both periods with at least a 3-h washed-out interval between the two periods. ABG were measured 5 min before and 25 min after endotracheal suctioning. The statistical tests showed that the levels of partial pressure of oxygen (PaO2 )/fraction of inspired oxygen (FiO2 ), partial pressure of carbon dioxide (PaCO2 ) and arterial oxygen saturation (SaO2 ) in the experimental period at 25 min after the intervention were significantly different from the control period. The tests also revealed that the levels of these variables at 25 min after suctioning were also significantly different from baseline values. However, these differences were clinically significant only for PaO2 /FiO2 . By improving the levels of PaO2 /FiO2 , ERCC can reduce the patients' need for oxygen and hence it can at least reduce the side effects of oxygen therapy. Improving PaO2 /FiO2 levels means less need for oxygen therapy. Hence, by applying ERCC we can at least minimize the side effects of oxygen therapy. © 2014 British Association of Critical Care Nurses.

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.

Pulmonary Mechanics and Mortality in Mechanically Ventilated Patients Without Acute Respiratory Distress Syndrome: A Cohort Study.

PubMed

Fuller, Brian M; Page, David; Stephens, Robert J; Roberts, Brian W; Drewry, Anne M; Ablordeppey, Enyo; Mohr, Nicholas M; Kollef, Marin H

2018-03-01

Driving pressure has been proposed as a major determinant of outcome in patients with acute respiratory distress syndrome (ARDS), but there is little data examining the association between pulmonary mechanics, including driving pressure, and outcomes in mechanically ventilated patients without ARDS. Secondary analysis from 1,705 mechanically ventilated patients enrolled in a clinical study that examined outcomes associated with the use of early lung-protective mechanical ventilation. The primary outcome was mortality and the secondary outcome was the incidence of ARDS. Multivariable models were constructed to: define the association between pulmonary mechanics (driving pressure, plateau pressure, and compliance) and mortality; and evaluate if driving pressure contributed information beyond that provided by other pulmonary mechanics. The mortality rate for the entire cohort was 26.0%. Compared with survivors, non-survivors had significantly higher driving pressure [15.9 (5.4) vs. 14.9 (4.4), P = 0.005] and plateau pressure [21.4 (5.7) vs. 20.4 (4.6), P = 0.001]. Driving pressure was independently associated with mortality [adjusted OR, 1.04 (1.01-1.07)]. Models related to plateau pressure also revealed an independent association with mortality, with similar effect size and interval estimates as driving pressure. There were 152 patients who progressed to ARDS (8.9%). Along with driving pressure and plateau pressure, mechanical power [adjusted OR, 1.03 (1.00-1.06)] was also independently associated with ARDS development. In mechanically ventilated patients, driving pressure and plateau pressure are risk factors for mortality and ARDS, and provide similar information. Mechanical power is also a risk factor for ARDS.

Performance of ICU ventilators during noninvasive ventilation with large leaks in a total face mask: a bench study* **

PubMed Central

Nakamura, Maria Aparecida Miyuki; Costa, Eduardo Leite Vieira; Carvalho, Carlos Roberto Ribeiro; Tucci, Mauro Roberto

2014-01-01

Objective: Discomfort and noncompliance with noninvasive ventilation (NIV) interfaces are obstacles to NIV success. Total face masks (TFMs) are considered to be a very comfortable NIV interface. However, due to their large internal volume and consequent increased CO2 rebreathing, their orifices allow proximal leaks to enhance CO2 elimination. The ventilators used in the ICU might not adequately compensate for such leakage. In this study, we attempted to determine whether ICU ventilators in NIV mode are suitable for use with a leaky TFM. Methods: This was a bench study carried out in a university research laboratory. Eight ICU ventilators equipped with NIV mode and one NIV ventilator were connected to a TFM with major leaks. All were tested at two positive end-expiratory pressure (PEEP) levels and three pressure support levels. The variables analyzed were ventilation trigger, cycling off, total leak, and pressurization. Results: Of the eight ICU ventilators tested, four did not work (autotriggering or inappropriate turning off due to misdetection of disconnection); three worked with some problems (low PEEP or high cycling delay); and one worked properly. Conclusions: The majority of the ICU ventilators tested were not suitable for NIV with a leaky TFM. PMID:25029653

Seven Ventilators Challenged With Leaks During Neonatal Nasal CPAP: An Experimental Pilot Study.

PubMed

Drevhammar, Thomas; Nilsson, Kjell; Zetterström, Henrik; Jonsson, Baldvin

2015-07-01

Nasal CPAP is the most common respiratory support for neonates. Several factors are considered important for effective treatment, including leaks at the patient interface and the delivery of pressure-stable CPAP. Investigations of pressure stability during leaks should include both the change in the mean delivered CPAP and the pressure variation during each breath. The aim of this study was to examine the response of ventilators delivering nasal CPAP when challenged with leaks at the patient interface. Seven ventilators providing nasal CPAP at 4 cm H2O were challenged with leaks during simulated neonatal breathing. Leak was applied for 15 consecutive breaths at a constant level (1-4 L/min). The 2 aspects of pressure stability were evaluated by measuring the mean delivered CPAP and the amplitude of pressure swings before, during, and after leaks. The ability to maintain the delivered CPAP and the amplitude of pressure swings varied greatly among the 7 ventilators before, during, and after leaks. Four of the ventilators tested have built-in leak compensation. There was no simple relationship between maintaining delivered CPAP during leaks and providing CPAP with low pressure swing amplitude. Maintaining the delivered CPAP and providing this without pressure swings are 2 separate aspects of pressure stability, and investigations concerning the clinical importance of pressure stability should address both aspects. This study also shows that compensation for leaks does not necessarily provide pressure-stable CPAP. Copyright © 2015 by Daedalus Enterprises.

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.

WASTE HANDLING BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT

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

P.A. Kumar

2000-06-21

The Waste Handling Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Handling Building (WHB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition to maintaining the proper environmental conditions for equipment operation and personnel comfort, the contamination confinement area ventilation system directs potentially contaminated air away from personnel in the WHB and confines the contamination within high-efficiency particulate air (HEPA) filtration units. Themore » contamination confinement areas ventilation system creates airflow paths and pressure zones to minimize the potential for spreading contamination within the building. The contamination confinement ventilation system also protects the environment and the public by limiting airborne releases of radioactive or other hazardous contaminants from the WHB. The Waste Handling Building Ventilation System is designed to perform its safety functions under accident conditions and other Design Basis Events (DBEs) (such as earthquakes, tornadoes, fires, and loss of the primary electric power). Additional system design features (such as compartmentalization with independent subsystems) limit the potential for cross-contamination within the WHB. The system provides status of important system parameters and equipment operation, and provides audible and/or visual indication of off-normal conditions and equipment failures. The Waste Handling Building Ventilation System confines the radioactive and hazardous material within the building such that the release rates comply with regulatory limits. The system design, operations, and maintenance activities incorporate ALARA (as low as is reasonably achievable) principles to maintain personnel radiation doses to all occupational workers below regulatory limits and as low as is reasonably achievable. The Waste Handling Building Ventilation System interfaces with the Waste Handling Building System by being located within the WHB and by maintaining specific pressures, temperatures, and humidity within the building. The system also depends on the WHB for water supply. The system interfaces with the Site Radiological Monitoring System for continuous monitoring of the exhaust air; the Waste Handling Building Fire Protection System for detection of fire and smoke; the Waste Handling Building Electrical System for normal, emergency, and standby power; and the Monitored Geologic Repository Operations Monitoring and Control System for monitoring and control of the system.« less

A new infant hybrid respiratory simulator: preliminary evaluation based on clinical data.

PubMed

Stankiewicz, Barbara; Pałko, Krzysztof J; Darowski, Marek; Zieliński, Krzysztof; Kozarski, Maciej

2017-11-01

A new hybrid (numerical-physical) simulator of the respiratory system, designed to simulate spontaneous and artificial/assisted ventilation of preterm and full-term infants underwent preliminary evaluation. A numerical, seven-compartmental model of the respiratory system mechanics allows the operator to simulate global and peripheral obstruction and restriction of the lungs. The physical part of the simulator is a piston-based construction of impedance transformer. LabVIEW real-time software coordinates the work of both parts of the simulator and its interaction with a ventilator. Using clinical data, five groups of "artificial infants" were examined: healthy full-term infants, very low-birth-weight preterm infants successfully (VLBW) and unsuccessfully extubated (VLBWun) and extremely low-birth-weight preterm infants without (ELBW) and with bronchopulmonary dysplasia (ELBW_BPD). Pressure-controlled ventilation was simulated to measure peak inspiratory pressure, mean airway pressure, total (patient + endotracheal tube) airway resistance (R), total dynamic compliance of the respiratory system (C), and total work of breathing by the ventilator (WOB). The differences between simulation and clinical parameters were not significant. High correlation coefficients between both types of data were obtained for R, C, and WOB (γ R  = 0.99, P < 0.0005; γ C  = 0.85, P < 0.005; γ WOB  = 0.96, P < 0.05, respectively). Thus, the simulator accurately reproduces infant respiratory system mechanics.

Bi-level positive airway pressure (BiPAP) and acute cardiogenic pulmonary oedema (ACPO) in the emergency department.

PubMed

Murray, Sarah

2002-05-01

Patients in acute respiratory failure (ARF) frequently present to the emergency department (ED). Traditionally management has involved mechanical ventilation via endotracheal intubation. Such invasive forms of treatment, however, correlate with a higher incidence of infection, mortality, length of stay and contribute to the costs of intensive care. Non-invasive positive pressure ventilation (NIPPV) such as bi-level positive airway pressure (BiPAP) may therefore provide an alternative and preferable form of treatment. Whilst contemporary literature supports the use of BiPAP in hypercapnic ARF, its role in acute hypoxaemic presentations remains elusive. Specifically, the efficacy and safety of BiPAP in the treatment of acute cardiogenic pulmonary oedema (ACPO) remains a contentious issue. The aim of this paper is to explore the physiological rationale for treatment of ACPO with BiPAP. Particular attention will focus on the comparative theoretical advantages of BiPAP in relation to continuous positive airway pressure (CPAP), and a review of recent research. Discussion will incorporate timeliness in the application of BiPAP, indicators of successful treatment, appropriate manipulation of pressure settings, nursing workload and management of patients beyond the ED. Whilst the theoretical advantages of BiPAP ventilation are acknowledged, larger randomised controlled research studies are recommended in order to clearly ensure its safe and effective application in the treatment of ACPO.

Servo-controlled pneumatic pressure oscillator for respiratory impedance measurements and high-frequency ventilation.

PubMed

Kaczka, David W; Lutchen, Kenneth R

2004-04-01

The ability to provide forced oscillatory excitation of the respiratory system can be useful in mechanical impedance measurements as well as high frequency ventilation (HFV). Experimental systems currently used for generating forced oscillations are limited in their ability to provide high amplitude flows or maintain the respiratory system at a constant mean pressure during excitation. This paper presents the design and implementation of a pneumatic pressure oscillator based on a proportional solenoid valve. The device is capable of providing forced oscillatory excitations to the respiratory system over a bandwidth suitable for mechanical impedance measurements and HVF. It delivers high amplitude flows (> 1.4 l/s) and utilizes a servo-control mechanism to maintain a load at a fixed mean pressure during simultaneous oscillation. Under open-loop conditions, the device exhibited a static hysteresis of approximately 7%, while its dynamic magnitude and phase responses were flat out to 10 Hz. Broad-band measurement of total harmonic distortion was approximately 19%. Under closed-loop conditions, the oscillator was able to maintain a mechanical test load at both positive and negative mean pressures during oscillatory excitations from 0.1 to 10.0 Hz. Impedance of the test load agreed closely with theoretical predictions. We conclude that this servo-controlled oscillator can be a useful tool for respiratory impedance measurements as well as HFV.

How to avoid microaspiration? A key element for the prevention of ventilator-associated pneumonia in intubated ICU patients.

PubMed

Blot, Stijn I; Poelaert, Jan; Kollef, Marin

2014-11-28

Microaspiration of subglottic secretions through channels formed by folds in high volume-low pressure poly-vinyl chloride cuffs of endotracheal tubes is considered a significant pathogenic mechanism of ventilator-associated pneumonia (VAP). Therefore a series of prevention measures target the avoidance of microaspiration. However, although some of these can minimize microaspiration, benefits in terms of VAP prevention are not always obvious. Polyurethane-cuffed endotracheal tubes successfully reduce microaspiration but high quality data demonstrating VAP rate reduction are lacking. An analogous conclusion can be made regarding taper-shaped cuffs compared with classic barrel-shaped cuffs. More clinical data regarding these endotracheal tube designs are needed to demonstrate clinical value in addition to in vitro-based evidence. The clinical usefulness of endotracheal tubes developed for subglottic secretions drainage is established in multiple studies and confirmed by meta-analysis. Any change in cuff design will fail to prevent microaspiration if the cuff is insufficiently inflated. At least one well-designed trial demonstrated that continuous cuff pressure monitoring and control decrease the risk of VAP. Gel lubrication of the cuff prior to intubation temporarily hampers microaspiration through sludging the channels formed by folds in high volume-low pressure cuffs. As the beneficial effect of gel lubrication is temporarily, its potential to reduce VAP risk is probably nonsignificant. A minimum positive end-expiratory pressure of at least 5 cmH2O can be recommended as it reduces the risk of microaspiration in vitro and in vivo. One randomized controlled study demonstrated a reduced risk of VAP in patients ventilated with PEEP (5-8 cmH2O). Regarding head-of-bed elevation, it can be recommended to avoid supine positioning. Whether a 45° head-of-bed elevation is to be preferred above 25-30° head-of-bed elevation remains unproven. Finally, the routine monitoring of gastric residual volumes in mechanically ventilated patients receiving enteral nutrition cannot be recommended.

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 ...

A prospective randomized trial of tapered-cuff endotracheal tubes with intermittent subglottic suctioning in preventing ventilator-associated pneumonia in critically ill patients.

PubMed

Mahmoodpoor, Ata; Hamishehkar, Hadi; Hamidi, Masoud; Shadvar, Kamran; Sanaie, Sarvin; Golzari, Samad Ej; Khan, Zahid Hussain; Nader, Nader D

2017-04-01

Endotracheal tube placement is necessary for the control of the airway in patients who are mechanically ventilated. However, prolonged duration of endotracheal tube placement contributes to the development of ventilator-associated pneumonias (VAPs). The aim of this study was to evaluate whether subglottic suctioning using TaperGuard EVAC tubes was effective in decreasing the frequency of VAP. A total of 276 mechanically ventilated patients for more than 72 hours were randomly assigned to group E (EVAC tube) and group C (conventional tube). All patients received routine care including VAP prevention measures during their intensive care unit stay. In group E, subglottic suctioning was performed every 6 hours. Outcome variables included incidence VAP, intensive care unit length of stay, and mortality. Frequency of intraluminal suction, mechanical ventilation-free days, reintubation, the ratio of arterial oxygen partial pressure to fractional inspired oxygen and mortality rate were similar between the 2 groups (P > .05). The mean cuff pressure in group E was significantly less than that in group C (P < .001). Ventilator-associated pneumonia was significantly less in group E compared with group C (P = .015). The use of intermittent subglottic secretion suctioning was associated with a significant decrease in the incidence of the VAP in critically ill patients. However, larger multicenter trials are required to arrive at a concrete decision on routine usage of TaperGuard tubes in critical care settings. Published by Elsevier Inc.

The effect of foot reflexology on physiologic parameters and mechanical ventilation weaning time in patients undergoing open-heart surgery: A clinical trial study.

PubMed

Ebadi, Abbas; Kavei, Parastoo; Moradian, Seyyed Tayyeb; Saeid, Yaser

2015-08-01

The aim of this study was to investigate the efficacy of foot reflexology on physiological parameters and mechanical ventilation weaning time in patients undergoing open-heart surgery. This was a double blind three-group randomized controlled trial. Totally, 96 patients were recruited and randomly allocated to the experimental, placebo, and the control groups. Study groups respectively received foot reflexology, simple surface touching, and the routine care of the study setting. Physiological parameters (pulse rate, respiratory rate, systolic and diastolic blood pressures, mean arterial pressure, percutaneous oxygen saturation) and weaning time were measured. The study groups did not differ significantly in terms of physiological parameters (P value > 0.05). However, the length of weaning time in the experimental group was significantly shorter than the placebo and the control groups (P value < 0.05). The study findings demonstrated the efficiency of foot reflexology in shortening the length of weaning time. Copyright © 2015 Elsevier Ltd. All rights reserved.

Requirements and Sizing Investigation for Constellation Space Suit Portable Life Support System Trace Contaminant Control

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Jennings, Mallory A.; Waguespack, Glenn

2010-01-01

The Trace Contaminant Control System (TCCS), located within the ventilation loop of the Constellation Space Suit Portable Life Support System (PLSS), is responsible for removing hazardous trace contaminants from the space suit ventilation flow. This paper summarizes the results of a trade study that evaluated if trace contaminant control could be accomplished without a TCCS, relying on suit leakage, ullage loss from the carbon dioxide and humidity control system, and other factors. Trace contaminant generation rates were revisited to verify that values reflect the latest designs for Constellation Space Suit System (CSSS) pressure garment materials and PLSS hardware. Additionally, TCCS sizing calculations were performed and a literature survey was conducted to review the latest developments in trace contaminant technologies.

Fast or Slow Rescue Ventilations: A Predictive Model of Gastric Inflation.

PubMed

Fitz-Clarke, John R

2018-05-01

Rescue ventilations are given during respiratory and cardiac arrest. Tidal volume must assure oxygen delivery; however, excessive pressure applied to an unprotected airway can cause gastric inflation, regurgitation, and pulmonary aspiration. The optimal technique provides mouth pressure and breath duration that minimize gastric inflation. It remains unclear if breath delivery should be fast or slow, and how inflation time affects the division of gas flow between the lungs and esophagus. A physiological model was used to predict and compare rates of gastric inflation and to determine ideal ventilation duration. Gas flow equations were based on standard pulmonary physiology. Gastric inflation was assumed to occur whenever mouth pressure exceeded lower esophageal sphincter pressure. Mouth pressure profiles that approximated mouth-to-mouth ventilation and bag-valve-mask ventilation were investigated. Target tidal volumes were set to 0.6 and 1.0 L. Compliance and airway resistance were varied. Rapid breaths shorter than 1 s required high mouth pressures, up to 25 cm H 2 O to achieve the target lung volume, which thus promotes gastric inflation. Slow breaths longer than 1 s permitted lower mouth pressures but increased time over which airway pressure exceeded lower esophageal sphincter pressure. The gastric volume increased with breath durations that exceeded 1 s for both mouth pressure profiles. Breath duration of ∼1.0 s caused the least gastric inflation in most scenarios. Very low esophageal sphincter pressure favored a shift toward 0.5 s. High resistance and low compliance each increased gastric inflation and altered ideal breath times. The model illustrated a general theory of optimal rescue ventilation. Breath duration with an unprotected airway should be 1 s to minimize gastric inflation. Short pressure-driven and long duration-driven gastric inflation regimens provide a unifying explanation for results in past studies. Copyright © 2018 by Daedalus Enterprises.

Expiratory rib cage compression in mechanically ventilated adults: systematic review with meta-analysis

PubMed Central

Borges, Lúcia Faria; Saraiva, Mateus Sasso; Saraiva, Marcos Ariel Sasso; Macagnan, Fabrício Edler; Kessler, Adriana

2017-01-01

Objective To review the literature on the effects of expiratory rib cage compression on ventilatory mechanics, airway clearance, and oxygen and hemodynamic indices in mechanically ventilated adults. Methods Systematic review with meta-analysis of randomized clinical trials in the databases MEDLINE (via PubMed), EMBASE, Cochrane CENTRAL, PEDro, and LILACS. Studies on adult patients hospitalized in intensive care units and under mechanical ventilation that analyzed the effects of expiratory rib cage compression with respect to a control group (without expiratory rib cage compression) and evaluated the outcomes static and dynamic compliance, sputum volume, systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, peripheral oxygen saturation, and ratio of arterial oxygen partial pressure to fraction of inspired oxygen were included. Experimental studies with animals and those with incomplete data were excluded. Results The search strategy produced 5,816 studies, of which only three randomized crossover trials were included, totaling 93 patients. With respect to the outcome of heart rate, values were reduced in the expiratory rib cage compression group compared with the control group [-2.81 bpm (95% confidence interval [95%CI]: -4.73 to 0.89; I2: 0%)]. Regarding dynamic compliance, there was no significant difference between groups [-0.58mL/cmH2O (95%CI: -2.98 to 1.82; I2: 1%)]. Regarding the variables systolic blood pressure and diastolic blood pressure, significant differences were found after descriptive evaluation. However, there was no difference between groups regarding the variables secretion volume, static compliance, ratio of arterial oxygen partial pressure to fraction of inspired oxygen, and peripheral oxygen saturation. Conclusion There is a lack of evidence to support the use of expiratory rib cage compression in routine care, given that the literature on this topic offers low methodological quality and is inconclusive. PMID:28444078

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.

Functional differences in bi-level pressure preset ventilators.

PubMed

Highcock, M P; Shneerson, J M; Smith, I E

2001-02-01

The performance of four bilevel positive pressure preset ventilators was compared. The ventilators tested were; BiPAP ST30 (Respironics); Nippy2 (B + D Electrical); Quantum PSV (Healthdyne); and Sullivan VPAP H ST (Resmed). A patient simulator was used to determine the sensitivity of the triggering mechanisms and the responses to a leak within the patient circuit, and to changes in patient effort. Significant differences (p <0.05) between the devices were seen in the trigger delay time and inspiratory trigger pressure. When a leak was introduced into the patient circuit, the fall in tidal volume (VT) was less than ten per cent for each ventilator. The addition of patient effort produced a number of changes in the ventilation delivered. Patient efforts of 0.25 s induced a variable fall in VT. An increase in VT was seen with some ventilators with patient efforts of 1 s but the effect was variable. Trigger failures and subsequent falls in minute volume were seen with the BiPAP and the Nippy2 at the highest respiratory frequency. Differences in the responses of the ventilators are demonstrated that may influence the selection of a ventilator, particularly in the treatment of breathless patients with ventilatory failure.

Effects of heat and moisture exchangers on minute ventilation, ventilatory drive, and work of breathing during pressure-support ventilation in acute respiratory failure.

PubMed

Pelosi, P; Solca, M; Ravagnan, I; Tubiolo, D; Ferrario, L; Gattinoni, L

1996-07-01

To evaluate the effect of two commonly used heat and moisture exchangers on respiratory function and gas exchange in patients with acute respiratory failure during pressure-support ventilation. Prospective, randomized trial. Intensive care unit of a university hospital. Fourteen patients with moderate acute respiratory failure, receiving pressure-support ventilation. Patients were assigned randomly to two treatment groups, in which two different heat and moisture exchangers were used: Hygroster (DAR S.p.A., Mirandola, Italy) with higher deadspace and lower resistance (group 1, n = 7), and Hygrobac-S (DAR S.p.A.) with lower deadspace and higher resistance (group 2, n = 7). Patients were assessed at three pressure-support levels: a) baseline (10.3 +/- 2.4 cm H2O for group 1, 9.3 +/- 1.3 cm H2O for group 2); b) 5 cm H2O above baseline; and c) 5 cm H2O below baseline. Measurements obtained with the heat and moisture exchangers were compared with those values obtained using the standard heated hot water humidifier. At baseline pressure-support ventilation, the insertion of both heat and moisture exchangers induced in all patients a significant increase in the following parameters: minute ventilation (12.4 +/- 3.2 to 15.0 +/- 2.6 L/min for group 1, and 11.8 +/- 3.6 to 14.2 +/- 3.5 L/min for group 2); static intrinsic positive end-expiratory pressure (2.9 +/- 2.0 to 5.1 +/- 3.2 cm H2O for group 1, and 2.9 +/- 1.7 to 5.5 +/- 3.0 cm H2O for group 2); ventilatory drive, expressed as P41 (2.7 +/- 2.0 to 5.2 +/- 4.0 cm H2O for group 1, and 3.3 +/- 2.0 to 5.3 +/- 3.0 cm H2O for group 2); and work of breathing, expressed as either power (8.8 +/- 9.4 to 14.5 +/- 10.3 joule/ min for group 1, and 10.5 +/- 7.4 to 16.6 +/- 11.0 joule/min for group 2) or work per liter of ventilation (0.6 +/- 0.6 to 1.0 +/- 0.7 joule/L for group 1, and 0.8 +/- 0.4 to 1.1 +/- 0.5 joule/L. for group 2). These increases also occurred when pressure-support ventilation was both above and below the baseline level, although at high pressure support the increase in work of breathing with heat and moisture exchangers was less evident. Gas exchange was unaffected by heat and moisture exchangers, as minute ventilation increased to compensate for the higher deadspace produced in the circuit by the insertion of heat and moisture exchangers. The tested heat and moisture exchangers should be used carefully in patients with acute respiratory failure during pressure-support ventilation, since these devices substantially increase minute ventilation, ventilatory drive, and work of breathing. However, an increase in pressure-support ventilation (5 to 10 cm H2O) may compensate for the increased work of breathing.

An Extracorporeal Artificial Placenta Supports Extremely Premature Lambs for One Week

PubMed Central

Bryner, Benjamin; Gray, Brian; Perkins, Elena; Davis, Ryan; Hoffman, Hayley; Barks, John; Owens, Gabe; Bocks, Martin; Rojas-Peña, Alvaro; Hirschl, Ronald; Bartlett, Robert; Mychaliska, George

2015-01-01

Purpose The treatment of extreme prematurity remains an unsolved problem. We developed an artificial placenta (AP) based on extracorporeal life support (ECLS) that simulates the intrauterine environment and provides gas exchange without mechanical ventilation (MV), and compared it to the current standard of neonatal care. Methods Extremely premature lambs (110-120d; term=145d) were used. AP lambs (n=9) were cannulated (jugular drainage, umbilical vein reinfusion) for ECLS .Control lambs (n=7) were intubated, ventilated, given surfactant, and transitioned to high-frequency oscillatory ventilation. All lambs received parenteral nutrition, antibiotics, and steroids. Hemodynamics, blood gases, hemoglobin, and circuit flows were measured. Results Four premature lambs survived for 1 week on the AP; one survived 6 days. Adequate oxygenation and ventilation were provided by the AP. The MV lambs survived 2-8 hours. Each of these lambs experienced a transient improvement with surfactant, but developed progressive hypercapnea and hypoxia despite high airway pressures and HFOV. Conclusions Extremely premature lambs were supported for 1 week with the AP with hemodynamic stability and adequate gas exchange; mechanically ventilated lambs succumbed within 8 hours. Further studies will assess control of fetal circulation and organ maturation on the AP. PMID:25598091

Hypoxic events and concomitant factors in preterm infants on non-invasive ventilation.

PubMed

Fathabadi, Omid Sadeghi; Gale, Timothy; Wheeler, Kevin; Plottier, Gemma; Owen, Louise S; Olivier, J C; Dargaville, Peter A

2017-04-01

Automated control of inspired oxygen for newborn infants is an emerging technology, currently limited by reliance on a single input signal (oxygen saturation, SpO 2 ). This is while other signals that may herald the onset of hypoxic events or identify spurious hypoxia are not usually utilised. We wished to assess the frequency of apnoea, loss of circuit pressure and/or motion artefact in proximity to hypoxic events in preterm infants on non-invasive ventilation. Hypoxic events (SpO 2  < 80 %) were identified using a previously acquired dataset obtained from preterm infants receiving non-invasive ventilation. Events with concomitant apnoea, loss of circuit pressure or oximetry motion artefact were annotated, and the frequency of each of these factors was determined. The effect of duration and timing of apnoea on the characteristics of the associated hypoxic events was studied. Among 1224 hypoxic events, 555 (45 %) were accompanied by apnoea, 31 (2.5 %) by loss of circuit pressure and 696 (57 %) by motion artefact, while for 224 (18 %) there were no concomitant factors identified. Respiratory pauses of longer duration (>15 s) preceding hypoxic events, were associated with a relatively slow decline in SpO 2 and more prolonged hypoxia compared to shorter pauses. Hypoxic events are frequently accompanied by respiratory pauses and/or motion artefact. Real-time monitoring and input of respiratory waveform may thus improve the function of automated oxygen controllers, allowing pre-emptive responses to respiratory pauses. Furthermore, use of motion-resistant oximeters and plethysmographic waveform assessment procedures will help to optimise feedback control of inspired oxygen delivery.

Change Is In the Air: What You Need to Know About Pharmacy Ventilation Under United States Pharmacopeia <800>.

PubMed

Laniewicz, Cheryl

2017-01-01

On July 1, 2018, United States Pharmacopeia <800> takes effect in those states that adopt it, and the discussion within this article may be applicable to those states that develop their own standards. United States Pharmacopeia <800> changes requirements for storage and compounding of hazardous drugs. The new requirements have important implications for air management and ventilation in some pharmacies. This article discusses how United States Pharmacopeia <800> compares to United States Pharmacopeia <797>, how the changes impact room ventilation and pressurization requirements, and how high-performance airflow control systems that ensure compliance and safety are impacted. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Immediate ventilatory response to sudden changes in venous return in humans.

PubMed Central

Cummin, A R; Iyawe, V I; Jacobi, M S; Mehta, N; Patil, C P; Saunders, K B

1986-01-01

We changed venous return transiently by postural manoeuvres, and by lower body positive pressure, to see what happened simultaneously to ventilation. Cardiac output was measured by a Doppler technique. In seven subjects, after inflation of a pressure suit to 80 and 40 mmHg at 30 deg head-up tilt, both cardiac output and ventilation increased. Ventilation increased rapidly to a peak in the first 5 s, cardiac output more slowly to a steady state in about 20 s, at 80 mmHg inflation. After inflation to 80 mmHg in six subjects at 12.5 deg head-up and 30 deg head-down tilt, cardiac output did not change in the first, and fell in the second case. There were no significant changes in ventilation. On release of pressure there were transient increases in both cardiac output and ventilation, with ventilation lagging behind cardiac output, in contrast to (2) above. In five subjects, elevation of the legs at 30 deg head-up tilt caused a rise in both cardiac output and ventilation, but in two subjects neither occurred. In all seven subjects there was a transient increase in cardiac output and ventilation when the legs were lowered. Ventilation and cardiac output changes were approximately in phase. We were therefore unable to dissociate entirely increasing cardiac output from increasing ventilation. The relation between them was certainly not a simple proportional one. PMID:3612571

Gas exchange and intrapulmonary distribution of ventilation during continuous-flow ventilation

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

Vettermann, J.; Brusasco, V.; Rehder, K.

1988-05-01

In 12 anesthetized paralyzed dogs, pulmonary gas exchange and intrapulmonary inspired gas distribution were compared between continuous-flow ventilation (CFV) and conventional mechanical ventilation (CMV). Nine dogs were studied while they were lying supine, and three dogs were studied while they were lying prone. A single-lumen catheter for tracheal insufflation and a double-lumen catheter for bilateral endobronchial insufflation (inspired O2 fraction = 0.4; inspired minute ventilation = 1.7 +/- 0.3 (SD) 1.kg-1.min-1) were evaluated. Intrapulmonary gas distribution was assessed from regional 133Xe clearances. In dogs lying supine, CO2 elimination was more efficient with endobronchial insufflation than with tracheal insufflation, but themore » alveolar-arterial O2 partial pressure difference was larger during CFV than during CMV, regardless of the type of insufflation. By contrast, endobronchial insufflation maintained both arterial PCO2 and alveolar-arterial O2 partial pressure difference at significantly lower levels in dogs lying prone than in dogs lying supine. In dogs lying supine, the dependent lung was preferentially ventilated during CMV but not during CFV. In dogs lying prone, gas distribution was uniform with both modes of ventilation. The alveolar-arterial O2 partial pressure difference during CFV in dogs lying supine was negatively correlated with the reduced ventilation of the dependent lung, which suggests that increased ventilation-perfusion mismatching was responsible for the increase in alveolar-arterial O2 partial pressure difference. The more efficient oxygenation during CFV in dogs lying prone suggests a more efficient matching of ventilation to perfusion, presumably because the distribution of blood flow is also nearly uniform.« less

Monitoring of noninvasive ventilation by built-in software of home bilevel ventilators: a bench study.

PubMed

Contal, Olivier; Vignaux, Laurence; Combescure, Christophe; Pepin, Jean-Louis; Jolliet, Philippe; Janssens, Jean-Paul

2012-02-01

Current bilevel positive-pressure ventilators for home noninvasive ventilation (NIV) provide physicians with software that records items important for patient monitoring, such as compliance, tidal volume (Vt), and leaks. However, to our knowledge, the validity of this information has not yet been independently assessed. Testing was done for seven home ventilators on a bench model adapted to simulate NIV and generate unintentional leaks (ie, other than of the mask exhalation valve). Five levels of leaks were simulated using a computer-driven solenoid valve (0-60 L/min) at different levels of inspiratory pressure (15 and 25 cm H(2)O) and at a fixed expiratory pressure (5 cm H(2)O), for a total of 10 conditions. Bench data were compared with results retrieved from ventilator software for leaks and Vt. For assessing leaks, three of the devices tested were highly reliable, with a small bias (0.3-0.9 L/min), narrow limits of agreement (LA), and high correlations (R(2), 0.993-0.997) when comparing ventilator software and bench results; conversely, for four ventilators, bias ranged from -6.0 L/min to -25.9 L/min, exceeding -10 L/min for two devices, with wide LA and lower correlations (R(2), 0.70-0.98). Bias for leaks increased markedly with the importance of leaks in three devices. Vt was underestimated by all devices, and bias (range, 66-236 mL) increased with higher insufflation pressures. Only two devices had a bias < 100 mL, with all testing conditions considered. Physicians monitoring patients who use home ventilation must be aware of differences in the estimation of leaks and Vt by ventilator software. Also, leaks are reported in different ways according to the device used.

[Airway Obstruction Caused by Heat and Moisture Exchange Filter Used during General Anesthesia: A Case Report and an In Vitro Study].

PubMed

Yoshidome, Aya; Shinomiya, Ayako; Iwagaki, Tamao; Sano, Haruhiko; Aoyama, Kazuyoshi; Takenaka, Yukari; Takenaka, Ichiro

2015-08-01

A previously healthy 54-year-old woman underwent a resection of the acoustic tumor. Following induction of general anesthesia and tracheal intubation, volume-controlled ventilation was started and the patient was placed in the left park bench position. The heat and moisture exchange filter (HMEF) was placed within the ventilatory circuit and positioned below the patient's head to avoid unintentional extubation. Six hours after the start of surgery, peak inspiratory pressure gradually rose, and 2 hours later ventilation of the patient's lung became increasingly difficult. When the HMEF was replaced, normal breathing was promptly restored. We reproduced this scenario with a similar HMEF under the same ventilator settings by adding 0-8 g of normal saline into the HMEF housing, and measured the inspiratory pressure and tidal volume across the HMEF. When instilling 4 g of saline, an increase in inspiratory pressure occurred. This case shows a potential risk of unexpectedly early occurrence of obstruction of the HMEF due to accumulation of condensed water within the device when the HMEF was positioned below the patient's head. We recommend selection of the appropriate HMEF and suitable mounting to avoid this problem.

Weaning from mechanical ventilation: why are we still looking for alternative methods?

PubMed

Frutos-Vivar, F; Esteban, A

2013-12-01

Most patients who require mechanical ventilation for longer than 24 hours, and who improve the condition leading to the indication of ventilatory support, can be weaned after passing a first spontaneous breathing test. The challenge is to improve the weaning of patients who fail that first test. We have methods that can be referred to as traditional, such as the T-tube, pressure support or synchronized intermittent mandatory ventilation (SIMV). In recent years, however, new applications of usual techniques as noninvasive ventilation, new ventilation methods such as automatic tube compensation (ATC), mandatory minute ventilation (MMV), adaptive support ventilation or automatic weaning systems based on pressure support have been described. Their possible role in weaning from mechanical ventilation among patients with difficult or prolonged weaning remains to be established. Copyright © 2012 Elsevier España, S.L. and SEMICYUC. All rights reserved.

Pleural liquid and kinetic friction coefficient of mesothelium after mechanical ventilation.

PubMed

Bodega, Francesca; Sironi, Chiara; Porta, Cristina; Zocchi, Luciano; Agostoni, Emilio

2015-01-15

Volume and protein concentration of pleural liquid in anesthetized rabbits after 1 or 3h of mechanical ventilation, with alveolar pressure equal to atmospheric at end expiration, were compared to those occurring after spontaneous breathing. Moreover, coefficient of kinetic friction between samples of visceral and parietal pleura, obtained after spontaneous or mechanical ventilation, sliding in vitro at physiological velocity under physiological load, was determined. Volume of pleural liquid after mechanical ventilation was similar to that previously found during spontaneous ventilation. This finding is contrary to expectation of Moriondo et al. (2005), based on measurement of lymphatic and interstitial pressure. Protein concentration of pleural liquid after mechanical ventilation was also similar to that occurring after spontaneous ventilation. Coefficient of kinetic friction after mechanical ventilation was 0.023±0.001, similar to that obtained after spontaneous breathing. Copyright © 2014 Elsevier B.V. All rights reserved.

Clinical assessment of auto-positive end-expiratory pressure by diaphragmatic electrical activity during pressure support and neurally adjusted ventilatory assist.

PubMed

Bellani, Giacomo; Coppadoro, Andrea; Patroniti, Nicolò; Turella, Marta; Arrigoni Marocco, Stefano; Grasselli, Giacomo; Mauri, Tommaso; Pesenti, Antonio

2014-09-01

Auto-positive end-expiratory pressure (auto-PEEP) may substantially increase the inspiratory effort during assisted mechanical ventilation. Purpose of this study was to assess whether the electrical activity of the diaphragm (EAdi) signal can be reliably used to estimate auto-PEEP in patients undergoing pressure support ventilation and neurally adjusted ventilatory assist (NAVA) and whether NAVA was beneficial in comparison with pressure support ventilation in patients affected by auto-PEEP. In 10 patients with a clinical suspicion of auto-PEEP, the authors simultaneously recorded EAdi, airway, esophageal pressure, and flow during pressure support and NAVA, whereas external PEEP was increased from 2 to 14 cm H2O. Tracings were analyzed to measure apparent "dynamic" auto-PEEP (decrease in esophageal pressure to generate inspiratory flow), auto-EAdi (EAdi value at the onset of inspiratory flow), and IDEAdi (inspiratory delay between the onset of EAdi and the inspiratory flow). The pressure necessary to overcome auto-PEEP, auto-EAdi, and IDEAdi was significantly lower in NAVA as compared with pressure support ventilation, decreased with increase in external PEEP, although the effect of external PEEP was less pronounced in NAVA. Both auto-EAdi and IDEAdi were tightly correlated with auto-PEEP (r = 0.94 and r = 0.75, respectively). In the presence of auto-PEEP at lower external PEEP levels, NAVA was characterized by a characteristic shape of the airway pressure. In patients with auto-PEEP, NAVA, compared with pressure support ventilation, led to a decrease in the pressure necessary to overcome auto-PEEP, which could be reliably monitored by the electrical activity of the diaphragm before inspiratory flow onset (auto-EAdi).

Backrest position in prevention of pressure ulcers and ventilator-associated pneumonia: Conflicting recommendations

PubMed Central

Burk, Ruth Srednicki; Jo Grap, Mary

2013-01-01

Pressure ulcers and ventilator-associated pneumonia (VAP) are both common in acute and critical care settings and are considerable sources of morbidity, mortality, and health care costs. To prevent pressure ulcers, guidelines limit bed backrest elevation to less than 30 degrees, whereas recommendations to reduce VAP include use of backrest elevations of 30 degrees or more. Although a variety of risk factors beyond patient position have been identified for both pressure ulcers and VAP, this article will focus on summarizing the major evidence for each of these apparently conflicting positioning strategies and discuss implications for practice in managing mechanically ventilated patients with risk factors for both pressure ulcers and VAP. PMID:22819601

Humidification performance of heat and moisture exchangers for pediatric use.

PubMed

Chikata, Yusuke; Sumida, Chihiro; Oto, Jun; Imanaka, Hideaki; Nishimura, Masaji

2012-01-01

Background. While heat and moisture exchangers (HMEs) have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH(2)O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small) and 5.1 L/min (large) when pressure was 10 cmH(2)O. We measured absolute humidity (AH) at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L), decreasing further (19.7 to 27.3 mg/L) with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent.

Humidification Performance of Heat and Moisture Exchangers for Pediatric Use

PubMed Central

Chikata, Yusuke; Sumida, Chihiro; Oto, Jun; Imanaka, Hideaki; Nishimura, Masaji

2012-01-01

Background. While heat and moisture exchangers (HMEs) have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH2O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small) and 5.1 L/min (large) when pressure was 10 cmH2O. We measured absolute humidity (AH) at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L), decreasing further (19.7 to 27.3 mg/L) with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent. PMID:22312483

Ventrain: an ejector ventilator for emergency use.

PubMed

Hamaekers, A E W; Borg, P A J; Enk, D

2012-06-01

A small, flow-regulated, manually operated ventilator designed for ventilation through a narrow-bore transtracheal catheter (TTC) has become available (Ventrain, Dolphys Medical BV, Eindhoven, The Netherlands). It is driven by a predetermined flow of oxygen from a high-pressure source and facilitates expiration by suction. The aim of this bench study was to test the efficacy of this new ventilator. The driving pressure, generated insufflation, and suction pressures and also the suction capacity of the Ventrain were measured at different oxygen flows. The minute volume achieved in an artificial lung through a TTC with an inner diameter (ID) of 2 mm was determined at different settings. Oxygen flows of 6-15 litre min(-1) resulted in driving pressures of 0.5-2.3 bar. Insufflation pressures, measured proximal to the TTC, ranged from 23 to 138 cm H(2)O. The maximal subatmospheric pressure build-up was -217 cm H(2)O. The suction capacity increased to a maximum of 12.4 litre min(-1) at an oxygen flow of 15 litre min(-1). At this flow, the achievable minute volume through the TTC ranged from 5.9 to 7.1 litres depending on the compliance of the artificial lung. The results of this bench study suggest that the Ventrain is capable of achieving a normal minute volume for an average adult through a 2 mm ID TTC. Further in vivo studies are needed to determine the value of the Ventrain as a portable emergency ventilator in a 'cannot intubate, cannot ventilate' situation.

Neurally Adjusted Ventilatory Assist After Pediatric Cardiac Surgery: Clinical Experience and Impact on Ventilation Pressures.

PubMed

Crulli, Benjamin; Khebir, Mariam; Toledano, Baruch; Vobecky, Suzanne; Poirier, Nancy; Emeriaud, Guillaume

2018-02-01

After pediatric cardiac surgery, ventilation with high airway pressures can be detrimental to right ventricular function and pulmonary blood flow. Neurally adjusted ventilatory assist (NAVA) improves patient-ventilator interactions, helping maintain spontaneous ventilation. This study reports our experience with the use of NAVA in children after a cardiac surgery. We hypothesize that using NAVA in this population is feasible and allows for lower ventilation pressures. We retrospectively studied all children ventilated with NAVA (invasively or noninvasively) after undergoing cardiac surgery between January 2013 and May 2015 in our pediatric intensive care unit. The number and duration of NAVA episodes were described. For the first period of invasive NAVA in each subject, detailed clinical and ventilator data in the 4 h before and after the start of NAVA were extracted. 33 postoperative courses were included in 28 subjects with a median age of 3 [interquartile range (IQR) 1-12] months. NAVA was used invasively in 27 courses for a total duration of 87 (IQR 15-334) h per course. Peak inspiratory pressures and mean airway pressures decreased significantly after the start of NAVA (mean differences of 5.8 cm H 2 O (95% CI 4.1-7.5) and 2.0 cm H 2 O (95% CI 1.2-2.8), respectively, P < .001 for both). There was no significant difference in vital signs or blood gas values. NAVA was used noninvasively in 14 subjects, over 79 (IQR 25-137) h. NAVA could be used in pediatric subjects after cardiac surgery. The significant decrease in airway pressures observed after transition to NAVA could have a beneficial impact in this specific population, which should be investigated in future interventional studies. Copyright © 2018 by Daedalus Enterprises.

A ventilation strategy during general anaesthesia to reduce postoperative atelectasis.

PubMed

Edmark, Lennart; Auner, Udo; Hallén, Jan; Lassinantti-Olowsson, Lena; Hedenstierna, Göran; Enlund, Mats

2014-08-01

Atelectasis is common during and after general anaesthesia. We hypothesized that a ventilation strategy, without recruitment manoeuvres, using a combination of continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) and a reduced end-expiratory oxygen fraction (FETO2) before ending mask ventilation with CPAP after extubation would reduce the area of postoperative atelectasis. Thirty patients were randomized into three groups. During induction and emergence, inspiratory oxygen fractions (FIO2) were 1.0 in the control group and 1.0 or 0.8 in the intervention groups. No CPAP/PEEP was used in the control group, whereas CPAP/PEEP of 6 cmH2O was used in the intervention groups. After extubation, FIO2 was set to 0.30 in the intervention groups and CPAP was applied, aiming at FETO2 < 0.30. Atelectasis was studied by computed tomography 25 min postoperatively. The median area of atelectasis was 5.2 cm(2) (range 1.6-12.2 cm(2)) and 8.5 cm(2) (3-23.1 cm(2)) in the groups given FIO2 1.0 with or without CPAP/PEEP, respectively. After correction for body mass index the difference between medians (2.9 cm(2)) was statistically significant (confidence interval 0.2-7.6 cm(2), p = 0.04). In the group given FIO2 0.8, in which seven patients were ex- or current smokers, the median area of atelectasis was 8.2 cm(2) (1.8-14.7 cm(2)). Compared with conventional ventilation, after correction for obesity, this ventilation strategy reduced the area of postoperative atelectasis in one of the intervention groups but not in the other group, which included a higher proportion of smokers.

A ventilation strategy during general anaesthesia to reduce postoperative atelectasis

PubMed Central

Auner, Udo; Hallén, Jan; Lassinantti-Olowsson, Lena; Hedenstierna, Göran; Enlund, Mats

2014-01-01

Background Atelectasis is common during and after general anaesthesia. We hypothesized that a ventilation strategy, without recruitment manoeuvres, using a combination of continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) and a reduced end-expiratory oxygen fraction (FETO2) before ending mask ventilation with CPAP after extubation would reduce the area of postoperative atelectasis. Methods Thirty patients were randomized into three groups. During induction and emergence, inspiratory oxygen fractions (FIO2) were 1.0 in the control group and 1.0 or 0.8 in the intervention groups. No CPAP/PEEP was used in the control group, whereas CPAP/PEEP of 6 cmH2O was used in the intervention groups. After extubation, FIO2 was set to 0.30 in the intervention groups and CPAP was applied, aiming at FETO2 < 0.30. Atelectasis was studied by computed tomography 25 min postoperatively. Results The median area of atelectasis was 5.2 cm2 (range 1.6–12.2 cm2) and 8.5 cm2 (3–23.1 cm2) in the groups given FIO2 1.0 with or without CPAP/PEEP, respectively. After correction for body mass index the difference between medians (2.9 cm2) was statistically significant (confidence interval 0.2–7.6 cm2, p = 0.04). In the group given FIO2 0.8, in which seven patients were ex- or current smokers, the median area of atelectasis was 8.2 cm2 (1.8–14.7 cm2). Conclusion Compared with conventional ventilation, after correction for obesity, this ventilation strategy reduced the area of postoperative atelectasis in one of the intervention groups but not in the other group, which included a higher proportion of smokers. PMID:24758245

Value and limitations of transpulmonary pressure calculations during intra-abdominal hypertension.

PubMed

Cortes-Puentes, Gustavo A; Gard, Kenneth E; Adams, Alexander B; Faltesek, Katherine A; Anderson, Christopher P; Dries, David J; Marini, John J

2013-08-01

To clarify the effect of progressively increasing intra-abdominal pressure on esophageal pressure, transpulmonary pressure, and functional residual capacity. Controlled application of increased intra-abdominal pressure at two positive end-expiratory pressure levels (1 and 10 cm H2O) in an anesthetized porcine model of controlled ventilation. Large animal laboratory of a university-affiliated hospital. Eleven deeply anesthetized swine (weight 46.2 ± 6.2 kg). Air-regulated intra-abdominal hypertension (0-25 mm Hg). Esophageal pressure, tidal compliance, bladder pressure, and end-expiratory lung aeration by gas dilution. Functional residual capacity was significantly reduced by increasing intra-abdominal pressure at both positive end-expiratory pressure levels (p ≤ 0.0001) without corresponding changes of end-expiratory esophageal pressure. Above intra-abdominal pressure 5 mm Hg, plateau airway pressure increased linearly by ~ 50% of the applied intra-abdominal pressure value, associated with commensurate changes of esophageal pressure. With tidal volume held constant, negligible changes occurred in transpulmonary pressure due to intra-abdominal pressure. Driving pressures calculated from airway pressures alone (plateau airway pressure--positive end-expiratory pressure) did not equate to those computed from transpulmonary pressure (tidal changes in transpulmonary pressure). Increasing positive end-expiratory pressure shifted the predominantly negative end-expiratory transpulmonary pressure at positive end-expiratory pressure 1 cm H2O (mean -3.5 ± 0.4 cm H2O) into the positive range at positive end-expiratory pressure 10 cm H2O (mean 0.58 ± 1.2 cm H2O). Despite its insensitivity to changes in functional residual capacity, measuring transpulmonary pressure may be helpful in explaining how different levels of positive end-expiratory pressure influence recruitment and collapse during tidal ventilation in the presence of increased intra-abdominal pressure and in calculating true transpulmonary driving pressure (tidal changes of transpulmonary pressure). Traditional interpretations of respiratory mechanics based on unmodified airway pressure were misleading regarding lung behavior in this setting.

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

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.

The performances of standard and ResMed masks during bag-valve-mask ventilation.

PubMed

Lee, Hyoung Youn; Jeung, Kyung Woon; Lee, Byung Kook; Lee, Seung Joon; Jung, Yong Hun; Lee, Geo Sung; Min, Yong Il; Heo, Tag

2013-01-01

A tight mask seal is frequently difficult to obtain and maintain during single-rescuer bag-valve-mask (BVM) ventilation. The ResMed mask (Bella Vista, NSW, Australia) is a continuous-positive-airway-pressure mask (CM) designed for noninvasive ventilation. In this study, we compared the ventilation performances of a standard mask (SM) and a ResMed CM using a simulation manikin in an out-of-hospital single-rescuer BVM ventilation scenario. Thirty emergency medical technicians (EMTs) performed two 2-minute attempts to ventilate a simulation manikin using BVM ventilation, alternatively, with the SM or the ResMed CM in a randomized order. Ventilation parameters including tidal volume and peak airway pressure were measured using computer analysis software connected to the simulation manikin. Successful volume delivery was defined as delivery of 440-540 mL of tidal volume in accord with present cardiopulmonary resuscitation guidelines. BVM ventilation using the ResMed CM produced higher mean (± standard deviation) tidal volumes (452 ± 50 mL vs. 394 ± 113 mL, p = 0.014) and had a higher proportion of successful volume deliveries (65.3% vs. 26.7%, p < 0.001) than that using the SM. Peak airway pressure was higher in BVM ventilation using the ResMed CM (p = 0.035). Stomach insufflation did not occur during either method. Twenty-nine of the participants (96.7%) preferred BVM ventilation using the ResMed CM. BVM ventilations using ResMed CM resulted in a significantly higher proportion of successful volume deliveries meeting the currently recommended range of tidal volume. Clinical studies are needed to determine the value of the ResMed CM for BVM ventilation.

Physiologic response to varying levels of pressure support and neurally adjusted ventilatory assist in patients with acute respiratory failure.

PubMed

Colombo, Davide; Cammarota, Gianmaria; Bergamaschi, Valentina; De Lucia, Marta; Corte, Francesco Della; Navalesi, Paolo

2008-11-01

Neurally adjusted ventilatory assist (NAVA) is a new mode wherein the assistance is provided in proportion to diaphragm electrical activity (EAdi). We assessed the physiologic response to varying levels of NAVA and pressure support ventilation (PSV). ICU of a University Hospital. Fourteen intubated and mechanically ventilated patients. DESIGN AND PROTOCOL: Cross-over, prospective, randomized controlled trial. PSV was set to obtain a VT/kg of 6-8 ml/kg with an active inspiration. NAVA was matched with a dedicated software. The assistance was decreased and increased by 50% with both modes. The six assist levels were randomly applied. Arterial blood gases (ABGs), tidal volume (VT/kg), peak EAdi, airway pressure (Paw), neural and flow-based timing. Asynchrony was calculated using the asynchrony index (AI). There was no difference in ABGs regardless of mode and assist level. The differences in breathing pattern, ventilator assistance, and respiratory drive and timing between PSV and NAVA were overall small at the two lower assist levels. At the highest assist level, however, we found greater VT/kg (9.1 +/- 2.2 vs. 7.1 +/- 2 ml/kg, P < 0.001), and lower breathing frequency (12 +/- 6 vs. 18 +/- 8.2, P < 0.001) and peak EAdi (8.6 +/- 10.5 vs. 12.3 +/- 9.0, P < 0.002) in PSV than in NAVA; we found mismatch between neural and flow-based timing in PSV, but not in NAVA. AI exceeded 10% in five (36%) and no (0%) patients with PSV and NAVA, respectively (P < 0.05). Compared to PSV, NAVA averted the risk of over-assistance, avoided patient-ventilator asynchrony, and improved patient-ventilator interaction.

Building America Case Study: Ventilation System Effectiveness and Tested Indoor Air Quality Impacts, Tyler, Texas

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

?Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, andmore » filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy.« less

Cardiopulmonary Laboratory AFSC 904X0

DTIC Science & Technology

1990-10-01

SET UP POSITIVE END EXPIRATORY PRESSURE (PEEP) DEVICES 100 J321 SET UP CONTINUOUS POSITIVE AIRWAY PRESSURE ( CPAP ) DEVICES 100 J298 ASSIST PHYSICIAN IN...PRESSURE VENTILATORS 61 COMPUTERIZED PULMONARY FUNCTION ANALYZERS 61 TREADMILLS 59 HOLTER MONITOR EQUIPMENT 57 CPAP EQUIPMENT 54 PRESSURE REGULATORS 48...SUCTIONING PROCEDURES 95 J321 SET UP CONTINUOUS POSITIVE AIRWAY PRESSURE ( CPAP ) DEVICES 95 J332 SET UP VOLUME VENTILATORS 93 F148 PERFORM ARTERIAL PUNCTURES 93

[Difficult Ventilation Requiring Emergency Endotracheal Intubation during Awake Craniotomy Managed by Laryngeal Mask Airway].

PubMed

Matsuda, Asako; Mizota, Toshiyuki; Tanaka, Tomoharu; Segawa, Hajime; Fukuda, Kazuhiko

2016-04-01

We report a case of difficult ventilation requiring emergency endotracheal intubation during awake craniotomy managed by laryngeal mask airway (LMA). A 45-year-old woman was scheduled to receive awake craniotomy for brain tumor in the frontal lobe. After anesthetic induction, airway was secured using ProSeal LMA and patient was mechanically ventilated in pressure-control mode. Patient's head was fixed with head-pins at anteflex position, and the operation started. About one hour after the start of the operation, tidal volume suddenly decreased. We immediately started manual ventilation, but the airway resistance was extremely high and we could not adequately ventilate the patient. We administered muscle relaxant for suspected laryngospasm, but ventilatory status did not improve; so we decided to conduct emergency endotracheal intubation. We tried to intubate using Airwayscope or LMA-Fastrach, but they were not effective in our case. Finally trachea was intubated using transnasal fiberoptic bronchoscopy. We discuss airway management during awake craniotomy, focusing on emergency endotracheal intubation during surgery.

Positive pressure ventilation in a patient with a right upper lobar bronchocutaneous fistula: right upper bronchus occlusion using the cuff of a left-sided double lumen endobronchial tube.

PubMed

Omori, Chieko; Toyama, Hiroaki; Takei, Yusuke; Ejima, Yutaka; Yamauchi, Masanori

2017-08-01

In patients with a bronchocutaneous fistula, positive pressure ventilation leads to air leakage and potential hypoxemia. A male patient with a right upper bronchocutaneous fistula was scheduled for esophageal reconstruction. His preoperative chest computed tomography image revealed aeration in the right middle and lower lobe, a large bulla in the left upper lobe, and pleural effusion and pneumonia in the left lower lobe. Therefore, left one-lung ventilation was considered to result in hypoxemia. Before anesthesia induction, the bronchocutaneous fistula was covered with gauze and film to prevent air leakage. After anesthesia induction, mask ventilation was performed with a peak positive pressure of 10 cmH 2 O. A left-sided double lumen endobronchial tube (DLT) was then inserted into the right main bronchus for occluding only the right superior bronchus, and two-lung ventilation was performed to minimize airway pressure and maintain oxygenation, which did not cause air leakage through the fistula. During anesthesia, no ventilation-related difficulty was faced. The method of inserting a left-sided DLT into the right main bronchus and occluding the right upper bronchus selectively by bronchial cuff is considered to be an option for mechanical ventilation in patients with a right upper bronchial fistula, as demonstrated in the present case.

Investigations of High Pressure Acoustic Waves in Resonators with Seal-like Features

NASA Technical Reports Server (NTRS)

Daniels, Christopher; Steinetz, Bruce; Finkbeiner, Joshua

2003-01-01

A conical resonator (having a dissonant acoustic design) was tested in four configurations: (1) baseline resonator with closed ends and no blockage, (2) closed resonator with internal blockage, (3) ventilated resonator with no blockage, and (4) ventilated resonator with an applied pressure differential. These tests were conducted to investigate the effects of blockage and ventilation holes on dynamic pressurization. Additionally, the investigation was to determine the ability of acoustic pressurization to impede flow through the resonator. In each of the configurations studied, the entire resonator was oscillated at the gas resonant frequency while dynamic pressure, static pressure, and temperature of the fluid were measured. In the final configuration, flow through the resonator was recorded for three oscillation conditions. Ambient condition air was used as the working fluid.

Chapter 5. Essential equipment, pharmaceuticals and supplies. Recommendations and standard operating procedures for intensive care unit and hospital preparations for an influenza epidemic or mass disaster.

PubMed

Sprung, Charles L; Kesecioglu, Jozef

2010-04-01

To provide recommendations and standard operating procedures for intensive care unit and hospital preparations for an influenza pandemic or mass disaster with a specific focus on essential equipment, pharmaceuticals and supplies. Based on a literature review and expert opinion, a Delphi process was used to define the essential topics including essential equipment, pharmaceuticals and supplies. Key recommendations include: (1) ensure that adequate essential medical equipment, pharmaceuticals and important supplies are available during a disaster; (2) develop a communication and coordination system between health care facilities and local/regional/state/country governmental authorities for the provision of additional support; (3) determine the required resources, order and stockpile adequate resources, and judiciously distribute them; (4) acquire additional mechanical ventilators that are portable, provide adequate gas exchange for a range of clinical conditions, function with low-flow oxygen and without high pressure, and are safe for patients and staff; (5) provide advanced ventilatory support and rescue therapies including high levels of inspired oxygen and positive end-expiratory pressure, volume and pressure control ventilation, inhaled nitric oxide, high-frequency ventilation, prone positioning ventilation and extracorporeal membrane oxygenation; (6) triage scarce resources including equipment, pharmaceuticals and supplies based on those who are likely to benefit most or on a 'first come, first served' basis. Judicious planning and adoption of protocols for providing adequate equipment, pharmaceuticals and supplies are necessary to optimize outcomes during a pandemic.

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.

Results of the Trace Contaminant Control Needs Evaluation and Sizing Study for Space Suit Life Support Development

NASA Technical Reports Server (NTRS)

Paul, Heather L.; Jennings, Mallory A.

2009-01-01

The Trace Contaminant Control System (TCCS), located within the ventilation loop of the Portable Life Support System (PLSS) of the Constellation Space Suit Element (CSSE), is responsible for removing hazardous trace contaminants from the space suit ventilation flow. This paper summarizes the results of a trade study that evaluated if trace contaminant control could be accomplished without a TCCS, relying on suit leakage, ullage loss from the carbon dioxide and humidity control system, and other factors. Trace contaminant generation rates were revisited to verify that values reflect the latest designs for CSSE pressure garment materials and PLSS hardware. Additionally, TCCS sizing calculations were performed and a literature survey was conducted to review the latest developments in trace contaminant technologies.

Cardiopulmonary and arterial baroreceptor unloading during passive hyperthermia does not contribute to hyperthermia-induced hyperventilation

PubMed Central

Lucas, Rebekah A. I.; Pearson, James; Schlader, Zachary J.; Crandall, Craig G.

2016-01-01

This study tested the hypothesis that baroreceptor unloading during passive hyperthermia contributes to increases in ventilation and decreases in end-tidal partial pressure of carbon dioxide (PET,CO2) during that exposure. Two protocols were performed, in which healthy subjects underwent passive hyperthermia (increasing intestinal temperature by ~1.8°C) to cause a sustained increase in ventilation and reduction in PET,CO2. Upon attaining hyperthermic hyperventilation, in protocol 1 (n = 10; three females) a bolus (19 ± 2 ml kg−1) of warm (~38°C) isotonic saline was rapidly (5–10 min) infused intravenously to restore reductions in central venous pressure, whereas in protocol 2 (n = 11; five females) phenylephrine was infused intravenously (60–120 μg min−1) to return mean arterial pressure to normothermic levels. In protocol 1, hyperthermia increased ventilation (by 2.2 ± 1.7 l min−1, P < 0.01), while reducing PET,CO2 (by 4 ± 3 mmHg, P = 0.04) and central venous pressure (by 5 ± 1 mmHg, P <0.01). Saline infusion increased central venous pressure by 5 ± 1 mmHg (P < 0.01), restoring it to normothermic values, but did not change ventilation or PET,CO2 (P > 0.05). In protocol 2, hyperthermia increased ventilation (by 5.0 ± 2.7l min−1, P <0.01) and reduced PET ,CO2 (by 5 ± 2 mmHg, P < 0.01) and mean arterial pressure (by 9 ± 7 mmHg, P <0.01). Phenylephrine infusion increased mean arterial pressure by 12 ± 3 mmHg (P < 0.01), restoring it to normothermic values, but did not change ventilation or PET,CO2 (P > 0.05). The absence of a reduction in ventilation upon reloading the cardiopulmonary and arterial baroreceptors to pre-hyperthermic levels indicates that baroreceptor unloading with hyperthermia is unlikely to contribute to hyperthermic hyperventilation in humans. PMID:26299270

Protective versus Conventional Ventilation for Surgery: A Systematic Review and Individual Patient Data Meta-analysis.

PubMed

Serpa Neto, Ary; Hemmes, Sabrine N T; Barbas, Carmen S V; Beiderlinden, Martin; Biehl, Michelle; Binnekade, Jan M; Canet, Jaume; Fernandez-Bustamante, Ana; Futier, Emmanuel; Gajic, Ognjen; Hedenstierna, Göran; Hollmann, Markus W; Jaber, Samir; Kozian, Alf; Licker, Marc; Lin, Wen-Qian; Maslow, Andrew D; Memtsoudis, Stavros G; Reis Miranda, Dinis; Moine, Pierre; Ng, Thomas; Paparella, Domenico; Putensen, Christian; Ranieri, Marco; Scavonetto, Federica; Schilling, Thomas; Schmid, Werner; Selmo, Gabriele; Severgnini, Paolo; Sprung, Juraj; Sundar, Sugantha; Talmor, Daniel; Treschan, Tanja; Unzueta, Carmen; Weingarten, Toby N; Wolthuis, Esther K; Wrigge, Hermann; Gama de Abreu, Marcelo; Pelosi, Paolo; Schultz, Marcus J

2015-07-01

Recent studies show that intraoperative mechanical ventilation using low tidal volumes (VT) can prevent postoperative pulmonary complications (PPCs). The aim of this individual patient data meta-analysis is to evaluate the individual associations between VT size and positive end-expiratory pressure (PEEP) level and occurrence of PPC. Randomized controlled trials comparing protective ventilation (low VT with or without high levels of PEEP) and conventional ventilation (high VT with low PEEP) in patients undergoing general surgery. The primary outcome was development of PPC. Predefined prognostic factors were tested using multivariate logistic regression. Fifteen randomized controlled trials were included (2,127 patients). There were 97 cases of PPC in 1,118 patients (8.7%) assigned to protective ventilation and 148 cases in 1,009 patients (14.7%) assigned to conventional ventilation (adjusted relative risk, 0.64; 95% CI, 0.46 to 0.88; P < 0.01). There were 85 cases of PPC in 957 patients (8.9%) assigned to ventilation with low VT and high PEEP levels and 63 cases in 525 patients (12%) assigned to ventilation with low VT and low PEEP levels (adjusted relative risk, 0.93; 95% CI, 0.64 to 1.37; P = 0.72). A dose-response relationship was found between the appearance of PPC and VT size (R2 = 0.39) but not between the appearance of PPC and PEEP level (R2 = 0.08). These data support the beneficial effects of ventilation with use of low VT in patients undergoing surgery. Further trials are necessary to define the role of intraoperative higher PEEP to prevent PPC during nonopen abdominal surgery.

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.

Backrest position in prevention of pressure ulcers and ventilator-associated pneumonia: conflicting recommendations.

PubMed

Burk, Ruth Srednicki; Grap, Mary Jo

2012-01-01

Pressure ulcers and ventilator-associated pneumonia (VAP) are both common in acute and critical care settings and are considerable sources of morbidity, mortality, and health care costs. To prevent pressure ulcers, guidelines limit bed backrest elevation to less than 30 degrees, whereas recommendations to reduce VAP include use of backrest elevations of 30 degrees or more. Although a variety of risk factors beyond patient position have been identified for both pressure ulcers and VAP, this article will focus on summarizing the major evidence for each of these apparently conflicting positioning strategies and discuss implications for practice in managing mechanically ventilated patients with risk factors for both pressure ulcers and VAP. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of prophylactic non-invasive mechanical ventilation on functional capacity after heart valve replacement: a clinical trial

PubMed Central

de Araújo-Filho, Amaro Afrânio; de Cerqueira-Neto, Manoel Luiz; de Assis Pereira Cacau, Lucas; Oliveira, Géssica Uruga; Cerqueira, Telma Cristina Fontes; de Santana-Filho, Valter Joviniano

2017-01-01

OBJECTIVE: During cardiac surgery, several factors contribute to the development of postoperative pulmonary complications. Non-invasive ventilation is a promising therapeutic tool for improving the functionality of this type of patient. The aim of this study is to evaluate the functional capacity and length of stay of patients in a nosocomial intensive care unit who underwent prophylactic non-invasive ventilation after heart valve replacement. METHOD: The study was a controlled clinical trial, comprising 50 individuals of both sexes who were allocated by randomization into two groups with 25 patients in each group: the control group and experimental group. After surgery, the patients were transferred to the intensive care unit and then participated in standard physical therapy, which was provided to the experimental group after 3 applications of non-invasive ventilation within the first 26 hours after extubation. For non-invasive ventilation, the positive pressure was 10 cm H2O, with a duration of 1 hour. The evaluation was performed on the 7th postoperative day/discharge and included a 6-minute walk test. The intensive care unit and hospitalization times were monitored in both groups. Brazilian Registry of Clinical Trials (REBeC): RBR number 8bxdd3. RESULTS: Analysis of the 6-minute walk test showed that the control group walked an average distance of 264.34±76 meters and the experimental group walked an average distance of 334.07±71 meters (p=0.002). The intensive care unit and hospitalization times did not differ between the groups. CONCLUSION: Non-invasive ventilation as a therapeutic resource was effective toward improving functionality; however, non-invasive ventilation did not influence the intensive care unit or hospitalization times of the studied cardiac patients. PMID:29160424

Effects of a preemptive alveolar recruitment strategy on arterial oxygenation during one-lung ventilation with different tidal volumes in patients with normal pulmonary function test.

PubMed

Jung, Jong Dal; Kim, Sang Hun; Yu, Byung Sik; Kim, Hye Ji

2014-08-01

Hypoxemia during one-lung ventilation (OLV) remains a major concern. The present study compared the effect of alveolar recruitment strategy (ARS) on arterial oxygenation during OLV at varying tidal volumes (Vt) with or without positive end-expiratory pressure (PEEP). In total, 120 patients undergoing wedge resection by video assisted thoracostomy were randomized into four groups comprising 30 patients each: those administered a 10 ml/kg tidal volume with or without preemptive ARS (Group H and Group H-ARS, respectively) and those administered a 6 ml/kg tidal volume and a 8 cmH2O PEEP with or without preemptive ARS (Group L and Group L-ARS, respectively). ARS was performed using pressure-controlled ventilation with a 40 cmH2O plateau airway pressure and a 15 cmH2O PEEP for at least 10 breaths until OLV began. Preemptive ARS significantly improved the PaO2/FiO2 ratio compared to the groups that did not receive ARS (P < 0.05). The H-ARS group showed a highest PaO2/FiO2 ratio during OLV, the L-ARS and H groups showed similarly improved arterial oxygenation, which was significantly higher than in group L (P < 0.05). The plateau airway pressure in group H-ARS was significantly higher than in group L-ARS (P < 0.05). Preemptive ARS can improve arterial oxygenation during OLV. Furthermore, a 6 ml/kg tidal volume combined with 8 cmH2O PEEP after preemptive ARS may reduce the risk of pulmonary injury caused by high tidal volume during one-lung ventilation in patients with normal pulmonary function.

Nasal mask ventilation is better than face mask ventilation in edentulous patients.

PubMed

Kapoor, Mukul Chandra; Rana, Sandeep; Singh, Arvind Kumar; Vishal, Vindhya; Sikdar, Indranil

2016-01-01

Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated. Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed. A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant. Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients.

Mechanical ventilation strategies for intensive care unit patients without acute lung injury or acute respiratory distress syndrome: a systematic review and network meta-analysis.

PubMed

Guo, Lei; Wang, Weiwei; Zhao, Nana; Guo, Libo; Chi, Chunjie; Hou, Wei; Wu, Anqi; Tong, Hongshuang; Wang, Yue; Wang, Changsong; Li, Enyou

2016-07-22

It has been shown that the application of a lung-protective mechanical ventilation strategy can improve the prognosis of patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). However, the optimal mechanical ventilation strategy for intensive care unit (ICU) patients without ALI or ARDS is uncertain. Therefore, we performed a network meta-analysis to identify the optimal mechanical ventilation strategy for these patients. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, EMBASE, MEDLINE, CINAHL, and Web of Science for studies published up to July 2015 in which pulmonary compliance or the partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FIO2) ratio was assessed in ICU patients without ALI or ARDS, who received mechanical ventilation via different strategies. The data for study characteristics, methods, and outcomes were extracted. We assessed the studies for eligibility, extracted the data, pooled the data, and used a Bayesian fixed-effects model to combine direct comparisons with indirect evidence. Seventeen randomized controlled trials including a total of 575 patients who received one of six ventilation strategies were included for network meta-analysis. Among ICU patients without ALI or ARDS, strategy C (lower tidal volume (VT) + higher positive end-expiratory pressure (PEEP)) resulted in the highest PaO2/FIO2 ratio; strategy B (higher VT + lower PEEP) was associated with the highest pulmonary compliance; strategy A (lower VT + lower PEEP) was associated with a shorter length of ICU stay; and strategy D (lower VT + zero end-expiratory pressure (ZEEP)) was associated with the lowest PaO2/FiO2 ratio and pulmonary compliance. For ICU patients without ALI or ARDS, strategy C (lower VT + higher PEEP) was associated with the highest PaO2/FiO2 ratio. Strategy B (higher VT + lower PEEP) was superior to the other strategies in improving pulmonary compliance. Strategy A (lower VT + lower PEEP) was associated with a shorter length of ICU stay, whereas strategy D (lower VT + ZEEP) was associated with the lowest PaO2/FiO2 ratio and pulmonary compliance.

Aerodynamic characteristics of the ventilated design for flapping wing micro air vehicle.

PubMed

Zhang, G Q; Yu, S C M

2014-01-01

Inspired by superior flight performance of natural flight masters like birds and insects and based on the ventilating flaps that can be opened and closed by the changing air pressure around the wing, a new flapping wing type has been proposed. It is known that the net lift force generated by a solid wing in a flapping cycle is nearly zero. However, for the case of the ventilated wing, results for the net lift force are positive which is due to the effect created by the "ventilation" in reducing negative lift force during the upstroke. The presence of moving flaps can serve as the variable in which, through careful control of the areas, a correlation with the decrease in negative lift can be generated. The corresponding aerodynamic characteristics have been investigated numerically by using different flapping frequencies and forward flight speeds.

Effect of acute kidney injury on weaning from mechanical ventilation in critically ill patients.

PubMed

Vieira, José M; Castro, Isac; Curvello-Neto, Américo; Demarzo, Sérgio; Caruso, Pedro; Pastore, Laerte; Imanishe, Marina H; Abdulkader, Regina C R M; Deheinzelin, Daniel

2007-01-01

Acute kidney injury (AKI) worsens outcome in various scenarios. We sought to investigate whether the occurrence of AKI has any effect on weaning from mechanical ventilation. Observational, retrospective study in a 23-bed medical/surgical intensive care unit (ICU) in a cancer hospital from January to December 2003. The inclusion criterion was invasive mechanical ventilation for > or =48 hrs. AKI was defined as at least one measurement of serum creatinine of > or =1.5 mg/dL during the ICU stay. Patients were then separated into AKI and non-AKI patients (control group). The criterion for weaning was the combination of positive end-expiratory pressure of < or =8 cm H2O, pressure support of < or =10 cm H2O, and Fio2 of < or =0.4, with spontaneous breathing. The primary end point was duration of weaning and the secondary end points were rate of weaning failure, total length of mechanical ventilation, length of stay in the ICU, and ICU mortality. A total of 140 patients were studied: 93 with AKI and 47 controls. The groups were similar in regard to age, sex, and type of tumor. Diagnosis of acute lung injury/acute respiratory distress syndrome as cause of respiratory failure and Simplified Acute Physiology Score II at admission did not differ between groups. During ICU stay, AKI patients had markers of more severe disease: increased occurrence of severe sepsis or septic shock, higher number of antibiotics, and longer use of vasoactive drugs. The median (interquartile range) duration of mechanical ventilation (10 [6-17] vs. 7 [2-12] days, p = .017) and duration of weaning from mechanical ventilation (41 [16-97] vs. 21 [7-33.5] hrs, p = .018) were longer in AKI patients compared with control patients. Cox regression analysis demonstrated that a > or =85% increase in baseline serum creatinine (hazard rate, 2.30; 95% confidence interval, 1.30-4.08), oliguria (hazard rate, 2.51; 95% confidence interval, 1.24-5.08), and the number of antibiotics (hazard rate, 2.64; 95% confidence interval, 1.51-4.63) predicted longer duration of weaning. The length of ICU stay and ICU mortality rate were significantly greater in the AKI patients. After adjusting for Simplified Acute Physiology Score II, oliguria (odds ratio, 30.8; 95% confidence interval, 7.7-123.0) remained as a strong risk factor for mortality. This study shows that renal dysfunction has serious consequences in the duration of mechanical ventilation, weaning from mechanical ventilation, and mortality in critically ill cancer patients.

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.

Mask pressure effects on the nasal bridge during short-term noninvasive ventilation

PubMed Central

Brill, Anne-Kathrin; Pickersgill, Rachel; Moghal, Mohammad; Morrell, Mary J.; Simonds, Anita K.

2018-01-01

The aim of this study was to assess the influence of different masks, ventilator settings and body positions on the pressure exerted on the nasal bridge by the mask and subjective comfort during noninvasive ventilation (NIV). We measured the pressure over the nasal bridge in 20 healthy participants receiving NIV via four different NIV masks (three oronasal masks, one nasal mask) at three different ventilator settings and in the seated or supine position. Objective pressure measurements were obtained with an I-Scan pressure-mapping system. Subjective comfort of the mask fit was assessed with a visual analogue scale. The masks exerted mean pressures between 47.6±29 mmHg and 91.9±42.4 mmHg on the nasal bridge. In the supine position, the pressure was lower in all masks (57.1±31.9 mmHg supine, 63.9±37.3 mmHg seated; p<0.001). With oronasal masks, a change of inspiratory positive airway pressure (IPAP) did not influence the objective pressure over the nasal bridge. Subjective discomfort was associated with higher IPAP and positively correlated with the pressure on the skin. Objective measurement of pressure on the skin during mask fitting might be helpful for mask selection. Mask fitting in the supine position should be considered in the clinical routine. PMID:29637077

Does Regional Lung Strain Correlate With Regional Inflammation in Acute Respiratory Distress Syndrome During Nonprotective Ventilation? An Experimental Porcine Study.

PubMed

Retamal, Jaime; Hurtado, Daniel; Villarroel, Nicolás; Bruhn, Alejandro; Bugedo, Guillermo; Amato, Marcelo Britto Passos; Costa, Eduardo Leite Vieira; Hedenstierna, Göran; Larsson, Anders; Borges, João Batista

2018-06-01

It is known that ventilator-induced lung injury causes increased pulmonary inflammation. It has been suggested that one of the underlying mechanisms may be strain. The aim of this study was to investigate whether lung regional strain correlates with regional inflammation in a porcine model of acute respiratory distress syndrome. Retrospective analysis of CT images and positron emission tomography images using [F]fluoro-2-deoxy-D-glucose. University animal research laboratory. Seven piglets subjected to experimental acute respiratory distress syndrome and five ventilated controls. Acute respiratory distress syndrome was induced by repeated lung lavages, followed by 210 minutes of injurious mechanical ventilation using low positive end-expiratory pressures (mean, 4 cm H2O) and high inspiratory pressures (mean plateau pressure, 45 cm H2O). All animals were subsequently studied with CT scans acquired at end-expiration and end-inspiration, to obtain maps of volumetric strain (inspiratory volume - expiratory volume)/expiratory volume, and dynamic positron emission tomography imaging. Strain maps and positron emission tomography images were divided into 10 isogravitational horizontal regions-of-interest, from which spatial correlation was calculated for each animal. The acute respiratory distress syndrome model resulted in a decrease in respiratory system compliance (20.3 ± 3.4 to 14.0 ± 4.9 mL/cm H2O; p < 0.05) and oxygenation (PaO2/FIO2, 489 ± 80 to 92 ± 59; p < 0.05), whereas the control animals did not exhibit changes. In the acute respiratory distress syndrome group, strain maps showed a heterogeneous distribution with a greater concentration in the intermediate gravitational regions, which was similar to the distribution of [F]fluoro-2-deoxy-D-glucose uptake observed in the positron emission tomography images, resulting in a positive spatial correlation between both variables (median R = 0.71 [0.02-0.84]; p < 0.05 in five of seven animals), which was not observed in the control animals. In this porcine acute respiratory distress syndrome model, regional lung strain was spatially correlated with regional inflammation, supporting that strain is a relevant and prominent determinant of ventilator-induced 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.

Constant-flow ventilation in canine experimental pulmonary emphysema.

PubMed

Hachenberg, T; Wendt, M; Meyer, J; Struckmeier, O; Lawin, P

1989-07-01

The efficacy of constant-flow ventilation (CFV) was investigated in eight mongrel dogs before (control-phase) and after development of papain-induced panlobular emphysema (PLE-phase). For CFV, heated, humidified and oxygen-enriched air was continuously delivered via two catheters positioned within each mainstem bronchus at flow rates (V) of 0.33, 0.5 and 0.66 l/s. Data obtained during intermittent positive pressure ventilation (IPPV) served as reference. In the control-phase, Pao2 was lower (P less than or equal to 0.05) and alveolo-arterial O2 difference (P(A-a)O2) was higher (P less than or equal to 0.01) during CFV at all flow rates when compared with IPPV. This may be due to inhomogeneities of intrapulmonary gas distribution and increased ventilation-perfusion (VA/Q) mismatching. Paco2 and V showed a hyperbolic relationship; constant normocapnia (5.3 kPa) was achieved at 0.48 +/- 0.21 l/s (V53). Development of PLE resulted in an increase of functional residual capacity (FRC), residual volume (RV) and static compliance (Cstat) (P less than or equal to 0.05). PaO2 had decreased and P(A-a)O2 had increased (P less than or equal to 0.05), indicating moderate pulmonary dysfunction. Oxygenation during CFV was not significantly different in the PLE-phase when compared with the control-phase. Paco2 and V showed a hyperbolic relationship and V5.3 was even lower than in the control-group (0.42 +/- 0.13 l/s). In dogs with emphysematous lungs CFV maintains sufficient gas exchange. This may be due to preferential ventilation of basal lung units, thereby counterbalancing the effects of impaired lung morphometry and increased airtrapping. Conventional mechanical ventilation is more effective in terms of oxygenation and CO2-elimination.

Ventilation through a small-bore catheter: optimizing expiratory ventilation assistance.

PubMed

Hamaekers, A E W; Borg, P A J; Götz, T; Enk, D

2011-03-01

Emergency ventilation through a small-bore transtracheal catheter can be lifesaving in a 'cannot intubate, cannot ventilate' situation. Ejectors, capable of creating suction by the Bernoulli principle, have been proposed to facilitate expiration through small-bore catheters. In this bench study, we compared a novel, purpose-built ventilation ejector (DE 5) with a previously proposed, modified industrial ejector (SBP 07). The generated insufflation pressures, suction pressures in static and dynamic situations, and also suction capacities and entrainment ratios of the SBP 07 and the DE 5 were determined. The DE 5 was also tested in a lung simulator with a simulated complete upper airway obstruction. Inspiratory and expiratory times through a transtracheal catheter were measured at various flow rates and achievable minute volumes were calculated. In a static situation, the SBP 07 showed a more negative pressure build-up compared with the DE 5. However, in a dynamic situation, the DE 5 generated a more negative pressure, resulting in a higher suction capacity. Employment of the DE 5 at a flow rate of 18 litre min(-1) allowed a minute volume through the transtracheal catheter of up to 8.27 litre min(-1) at a compliance of 100 ml cm H(2)O(-1). The efficiency of the DE 5 depended on the flow rate of the driving gas and the compliance of the lung simulator. In laboratory tests, the DE 5 is an optimized ventilation ejector suitable for applying expiratory ventilation assistance. Further research may confirm the clinical applicability as a portable emergency ventilator for use with small-bore catheters.

Evaluating the effects of protective ventilation on organ-specific cytokine production in porcine experimental postoperative sepsis.

PubMed

Sperber, Jesper; Lipcsey, Miklós; Larsson, Anders; Larsson, Anders; Sjölin, Jan; Castegren, Markus

2015-05-10

Protective ventilation with lower tidal volume (VT) and higher positive end-expiratory pressure (PEEP) reduces the negative additive effects of mechanical ventilation during systemic inflammatory response syndrome. We hypothesised that protective ventilation during surgery would affect the organ-specific immune response in an experimental animal model of endotoxin-induced sepsis-like syndrome. 30 pigs were laparotomised for 2 hours (h), after which a continuous endotoxin infusion was started at 0.25 micrograms × kg(-1) × h(-1) for 5 h. Catheters were placed in the carotid artery, hepatic vein, portal vein and jugular bulb. Animals were randomised to two protective ventilation groups (n = 10 each): one group was ventilated with VT 6 mL × kg(-1) during the whole experiment while the other group was ventilated during the surgical phase with VT of 10 mL × kg(-1). In both groups PEEP was 5 cmH2O during surgery and increased to 10 cmH2O at the start of endotoxin infusion. A control group (n = 10) was ventilated with VT of 10 mL × kg(-1) and PEEP 5 cm H20 throughout the experiment. In four sample locations we a) simultaneously compared cytokine levels, b) studied the effect of protective ventilation initiated before and during endotoxemia and c) evaluated protective ventilation on organ-specific cytokine levels. TNF-alpha levels were highest in the hepatic vein, IL-6 levels highest in the artery and jugular bulb and IL-10 levels lowest in the artery. Protective ventilation initiated before and during endotoxemia did not differ in organ-specific cytokine levels. Protective ventilation led to lower levels of TNF-alpha in the hepatic vein compared with the control group, whereas no significant differences were seen in the artery, portal vein or jugular bulb. Variation between organs in cytokine output was observed during experimental sepsis. We see no implication from cytokine levels for initiating protective ventilation before endotoxemia. However, during endotoxemia protective ventilation attenuates hepatic inflammatory cytokine output contributing to a reduced total inflammatory burden.

Initial mechanical ventilator settings and lung protective ventilation in the ED.

PubMed

Wilcox, Susan R; Richards, Jeremy B; Fisher, Daniel F; Sankoff, Jeffrey; Seigel, Todd A

2016-08-01

Mechanical ventilation with low tidal volumes has been shown to improve outcomes for patients both with and without acute respiratory distress syndrome. This study aims to characterize mechanically ventilated patients in the emergency department (ED), describe the initial ED ventilator settings, and assess for associations between lung protective ventilation strategies in the ED and outcomes. This was a multicenter, prospective, observational study of mechanical ventilation at 3 academic EDs. We defined lung protective ventilation as a tidal volume of less than or equal to 8 mL/kg of predicted body weight and compared outcomes for patients ventilated with lung protective vs non-lung protective ventilation, including inhospital mortality, ventilator days, intensive care unit length of stay, and hospital length of stay. Data from 433 patients were analyzed. Altered mental status without respiratory pathology was the most common reason for intubation, followed by trauma and respiratory failure. Two hundred sixty-one patients (60.3%) received lung protective ventilation, but most patients were ventilated with a low positive end-expiratory pressure, high fraction of inspired oxygen strategy. Patients were ventilated in the ED for a mean of 5 hours and 7 minutes but had few ventilator adjustments. Outcomes were not significantly different between patients receiving lung protective vs non-lung protective ventilation. Nearly 40% of ED patients were ventilated with non-lung protective ventilation as well as with low positive end-expiratory pressure and high fraction of inspired oxygen. Despite a mean ED ventilation time of more than 5 hours, few patients had adjustments made to their ventilators. Copyright © 2016 Elsevier Inc. All rights reserved.

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.

Obstructive sleep apnea and insight into mechanisms of sympathetic overactivity.

PubMed

Abboud, François; Kumar, Ravinder

2014-04-01

Nearly two decades ago, we evaluated ten patients with obstructive sleep apnea (OSA). We determined that alarming nocturnal oscillations in arterial pressure and sympathetic nerve activity (SNA) were caused by regulatory coupling and neural interactions among SNA, apnea, and ventilation. Patients with OSA exhibited high levels of SNA when awake, during normal ventilation, and during normoxia, which contributed to hypertension and organ damage. Additionally, we achieved a beneficial and potentially lifesaving reduction in SNA through the application of continuous positive airway pressure (CPAP), which remains a primary therapeutic approach for patients with OSA. With these results in hindsight, we herein discuss three concepts with functional and therapeutic relevance to the integrative neurobiology of autonomic cardiovascular control and to the mechanisms involved in excessive sympathoexcitation in OSA.

Developing a new, national approach to surveillance for ventilator-associated events*.

PubMed

Magill, Shelley S; Klompas, Michael; Balk, Robert; Burns, Suzanne M; Deutschman, Clifford S; Diekema, Daniel; Fridkin, Scott; Greene, Linda; Guh, Alice; Gutterman, David; Hammer, Beth; Henderson, David; Hess, Dean; Hill, Nicholas S; Horan, Teresa; Kollef, Marin; Levy, Mitchell; Septimus, Edward; VanAntwerpen, Carole; Wright, Don; Lipsett, Pamela

2013-11-01

To develop and implement an objective, reliable approach to surveillance for ventilator-associated events in adult patients. The Centers for Disease Control and Prevention (CDC) convened a Ventilator-Associated Pneumonia (VAP) Surveillance Definition Working Group in September 2011. Working Group members included representatives of stakeholder societies and organizations and federal partners. The Working Group finalized a three-tier, adult surveillance definition algorithm for ventilator-associated events. The algorithm uses objective, readily available data elements and can identify a broad range of conditions and complications occurring in mechanically ventilated adult patients, including but not limited to VAP. The first tier definition, ventilator-associated condition (VAC), identifies patients with a period of sustained respiratory deterioration following a sustained period of stability or improvement on the ventilator, defined by changes in the daily minimum fraction of inspired oxygen or positive end-expiratory pressure. The second tier definition, infection-related ventilator-associated complication (IVAC), requires that patients with VAC also have an abnormal temperature or white blood cell count, and be started on a new antimicrobial agent. The third tier definitions, possible and probable VAP, require that patients with IVAC also have laboratory and/or microbiological evidence of respiratory infection. Ventilator-associated events surveillance was implemented in January 2013 in the CDC's National Healthcare Safety Network. Modifications to improve surveillance may be made as additional data become available and users gain experience with the new definitions.

Mobile communication devices causing interference in invasive and noninvasive ventilators.

PubMed

Dang, Bao P; Nel, Pierre R; Gjevre, John A

2007-06-01

The aim of this study was to assess if common mobile communication systems would cause significant interference on mechanical ventilation devices and at what distances would such interference occur. We tested all the invasive and noninvasive ventilatory devices used within our region. This consisted of 2 adult mechanical ventilators, 1 portable ventilator, 2 pediatric ventilators, and 2 noninvasive positive pressure ventilatory devices. We operated the mobile devices from the 2 cellular communication systems (digital) and 1 2-way radio system used in our province at varying distances from the ventilators and looked at any interference they created. We tested the 2-way radio system, which had a fixed operation power output of 3.0 watts, the Global Systems for Mobile Communication cellular system, which had a maximum power output of 2.0 watts and the Time Division Multiple Access cellular system, which had a maximum power output of 0.2 watts on our ventilators. The ventilators were ventilating a plastic lung at fixed settings. The mobile communication devices were tested at varying distances starting at zero meter from the ventilator and in all operation modes. The 2-way radio caused the most interference on some of the ventilators, but the maximum distance of interference was 1.0 m. The Global Systems for Mobile Communication system caused significant interference only at 0 m and minor interference at 0.5 m on only 1 ventilator. The Time Division Multiple Access system caused no interference at all. Significant interference consisted of a dramatic rise and fluctuation of the respiratory rate, pressure, and positive end-expiratory pressure of the ventilators with no normalization when the mobile device was removed. From our experiment on our ventilators with the communication systems used in our province, we conclude that mobile communication devices such as cellular phones and 2-way radios are safe and cause no interference unless operated at very close distances of less than 1 meter.

Intraoperative protective mechanical ventilation and risk of postoperative respiratory complications: hospital based registry study.

PubMed

Ladha, Karim; Vidal Melo, Marcos F; McLean, Duncan J; Wanderer, Jonathan P; Grabitz, Stephanie D; Kurth, Tobias; Eikermann, Matthias

2015-07-14

To evaluate the effects of intraoperative protective ventilation on major postoperative respiratory complications and to define safe intraoperative mechanical ventilator settings that do not translate into an increased risk of postoperative respiratory complications. Hospital based registry study. Academic tertiary care hospital and two affiliated community hospitals in Massachusetts, United States. 69,265 consecutively enrolled patients over the age of 18 who underwent a non-cardiac surgical procedure between January 2007 and August 2014 and required general anesthesia with endotracheal intubation. Protective ventilation, defined as a median positive end expiratory pressure (PEEP) of 5 cmH2O or more, a median tidal volume of less than 10 mL/kg of predicted body weight, and a median plateau pressure of less than 30 cmH2O. Composite outcome of major respiratory complications, including pulmonary edema, respiratory failure, pneumonia, and re-intubation. Of the 69,265 enrolled patients 34,800 (50.2%) received protective ventilation and 34,465 (49.8%) received non-protective ventilation intraoperatively. Protective ventilation was associated with a decreased risk of postoperative respiratory complications in multivariable regression (adjusted odds ratio 0.90, 95% confidence interval 0.82 to 0.98, P=0.013). The results were similar in the propensity score matched cohort (odds ratio 0.89, 95% confidence interval 0.83 to 0.97, P=0.004). A PEEP of 5 cmH2O and median plateau pressures of 16 cmH2O or less were associated with the lowest risk of postoperative respiratory complications. Intraoperative protective ventilation was associated with a decreased risk of postoperative respiratory complications. A PEEP of 5 cmH2O and a plateau pressure of 16 cmH2O or less were identified as protective mechanical ventilator settings. These findings suggest that protective thresholds differ for intraoperative ventilation in patients with normal lungs compared with those used for patients with acute lung injury. © Ladha et al 2015.

An overview of changes in pressure values of the middle ear using impedance audiometry among diver candidates in a hyperbaric chamber before and after a pressure test

NASA Astrophysics Data System (ADS)

Anoraga, J. S.; Bramantyo, B.; Bardosono, S.; Simanungkalit, S. H.; Basiruddin, J.

2017-08-01

Impedance audiometry is not yet routinely used in pressure tests, especially in Indonesia. Direct exposure to pressure in a hyperbaric chamber is sometimes without any assessment of the middle ear or the Eustachian tube function (ETF) of ventilation. Impedance audiometry examinations are important to assess ETF ventilation. This study determined the middle ear pressure value changes associated with the ETF (ventilation) of prospective divers. This study included 29 prospective divers aged 20-40 years without conductive hearing loss. All subjects underwent a modified diving impedance audiometry examination both before and after the pressure test in a double-lock hyperbaric chamber. Using the Toynbee maneuver, the values obtained for changes of pressure in the middle ear were significant before and after the pressure test in the right and left ears: p < 0.001 and p = 0.018, respectively. The impedance audiometry examination is necessary for the selection of candidate divers undergoing pressure tests within a hyperbaric chamber.

The Effect of Airway Pressure Release Ventilation on Pulmonary Catheter Readings: Specifically Pulmonary Capillary Wedge Pressure in a Swine Model

DTIC Science & Technology

2011-01-01

pressure (PEEP) of 5 cm H2O was initiated. Ventilator mode was changed to APRV with incremental elevations of CPAP -high from 10 to 35 cm H2O. After a...Results. Increasing CPAP caused increased PCWP and LAPmeasurements above their baseline values. Mean PCWP and LAP were linearly related (LAP = 0.66...PCWP + 4.5 cmH2O, R2 = 0.674, and P < .001) over a wide range of high and low CPAP values during APRV. With return to conventional ventilation, PCWP

Mechanisms of decreased left ventricular preload during continuous positive pressure ventilation in ARDS

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

Dhainaut, J.F.; Devaux, J.Y.; Monsallier, J.F.

1986-07-01

Continuous positive pressure ventilation is associated with a reduction in left ventricular preload and cardiac output, but the mechanisms responsible are controversial. The decrease in left ventricular preload may result exclusively from a decreased systemic venous return due to increased pleural pressure, or from an additional effect such as decreased left ventricular compliance. To determine the mechanisms responsible, we studied the changes in cardiac output induced by continuous positive pressure ventilation in eight patients with the adult respiratory distress syndrome. We measured cardiac output by thermodilution, and biventricular ejection fraction by equilibrium gated blood pool scintigraphy. Biventricular end-diastolic volumes weremore » then calculated by dividing stroke volume by ejection fraction. As positive end-expiratory pressure increased from 0 to 20 cm H/sub 2/O, stroke volume and biventricular end-diastolic volumes fell about 25 percent, and biventricular ejection fraction remained unchanged. At 20 cm H/sub 2/O positive end-expiratory pressure, volume expansion for normalizing cardiac output restored biventricular end-diastolic volumes without markedly changing biventricular end-diastolic transmural pressures. The primary cause of the reduction in left ventricular preload with continuous positive pressure ventilation appears to be a fall in venous return and hence in right ventricular stroke volume, without evidence of change in left ventricular diastolic compliance.« 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.

Automated Control of Endotracheal Tube Cuff Pressure during Simulated Flight

DTIC Science & Technology

2016-06-21

accomplished in the intensive care unit (ICU) with stand-alone devices as well as those integral to a ventilator [13,14]. We hypothesized that closed loop ... Administration approved automatic cuff pressure adjustment devices (Intellicuff, Hamilton Medical , Reno, NV; Pyton, ARM Medical , Bristol, CT; Cuff Sentry, Outcome...711th Human Performance Wing U.S. Air Force School of Aerospace Medicine Int’l Expeditionary Educ & Training Dept Air Force Expeditionary Medical

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.

Field evaluation of an engineering control for respirable crystalline silica exposures during mortar removal.

PubMed

Collingwood, Scott; Heitbrink, William A

2007-11-01

During mortar removal with a right angle grinder, a building renovation process known as "tuck pointing," worker exposures to respirable crystalline silica can be as high as 5 mg/m(3), 100 times the recommended exposure limit developed by the National Institute for Occupational Safety and Health. To reduce the risk of silicosis among these workers, a vacuum cleaner can be used to exhaust 80 ft(3)/min (2.26 m(3)/min) from a hood mounted on the grinder. Field trials examined the ability of vacuum cleaners to maintain adequate exhaust ventilation rates and measure exposure outcomes when using this engineering control. These field trials involved task-based exposure measurement of respirable dust and crystalline silica exposures during mortar removal. These measurements were compared with published exposure data. Vacuum cleaner airflows were obtained by measuring and digitally logging vacuum cleaner static pressure at the inlet to the vacuum cleaner motor. Static pressures were converted to airflows based on experimentally determined fan curves. In two cases, video exposure monitoring was conducted to study the relationship between worker activities and dust exposure. Worker activities were video taped concurrent with aerosol photometer measurement of dust exposure and vacuum cleaner static pressure as a measure of airflow. During these field trials, respirable crystalline silica exposures for 22 samples had a geometric mean of 0.06 mg/m(3) and a range of less than 0.01 to 0.86 mg/m(3). For three other studies, respirable crystalline silica exposures during mortar removal have a geometric means of 1.1 to 0.35. Although this field study documented noticeably less exposure to crystalline silica, video exposure monitoring found that the local exhaust ventilation provided incomplete dust control due to low exhaust flow rates, certain work practices, and missing mortar. Vacuum cleaner airflow decrease had a range of 3 to 0.4 ft(3)/min (0.08 to 0.01 m(3)/sec(2)) over a range of vacuum cleaners, hose diameters, and hose lengths. To control worker exposure to respirable crystalline silica, local exhaust ventilation needs to be incorporated into a comprehensive silica control program that includes respiratory protection, worker training, and local exhaust ventilation.

[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.

Automatic Tube Compensation versus Pressure Support Ventilation and Extubation Outcome in Children: A Randomized Controlled Study

PubMed Central

El-beleidy, Ahmed Saad El-din; Khattab, Asser Abd EL-Hamied; El-Sherbini, Seham Awad; Al-gebaly, Hebatalla Fadel

2013-01-01

Background. Automatic tube compensation (ATC) has been developed to overcome the imposed work of breathing due to artificial airways during spontaneous breathing trials (SBTs). Objectives. This study aimed to assess extubation outcome after an SBT (spontaneous breathing trial) with ATC compared with pressure support ventilation (PSV) and to determine the risk factors for extubation failure. Methods. Patients ready for extubation were randomly assigned to two-hour spontaneous breathing trial with either ATC or pressure support ventilation. Results. In the ATC group (n = 17), 11 (65%) patients passed the SBT with subsequent extubation failure (9%). While in PSV group (n = 19), 10 (53%) patients passed the SBT with subsequent extubation failure (10%). This represented a positive predictive value for ATC of 91% and PSV of 90% (P = 0.52). Five (83%) of the patients who failed the SBT in ATC group were reintubated. This represented a higher negative predictive value for ATC of 83% than for PSV which was 56%. None of the assessed risk factors were independently associated with extubation failure including failed trial. Conclusion. ATC was equivalent to PSV in predicting patients with successful extubation. A trial failure in ATC group is associated with but does not definitely predict extubation failure. PMID:23533800

[Special artificial respiration procedures and intracranial pressure. Animal experiment studies, development and use of a new pressure measuring technic, clinical aspects].

PubMed

Schedl, R

1985-01-01

We investigated the influence of Forced Diffusion Ventilation (FDV), a special form of High Frequency Ventilation (HFV), on elevated intracranial pressure (ICP) in 5 dogs. Elevation of ICP was standardized by inflation of an epidural balloon. A typical finding with FDV is a reduced intrapleural pressure and therefore one could expect a better cerebrovenous drainage influencing ICP. Nevertheless, we found no changes in mean ICP under conditions of FDV compared with IPPV. Respirator-synchronous fluctuations of ICP, cisternal cerebrospinal fluid pressure and intrapleural pressure were drastically reduced with FDV. This phenomenon has been already reported by other groups as a typical effect of HFV with rates of 100/min. One can speculate, that this immediate impact of HFV on ICP-curves might be of some advantage in patients with critically reduced intracranial compliance requiring long-term artificial ventilation, because peaks and amplitudes of ICP are reduced. Our clinical experience with High Frequency Pulsation (HFP) includes 11 patients with severe brain trauma. In clinical routine this method of HFV is more facile to applicate than FDV, because there is no need of a special endotracheal tube and sufficient CO2-elimination is not strongly dependent on precise position of the tube. But HFP, as FDV, includes all advantages of respiratory systems, that are open against atmosphere (coughing and simultaneous breathing, without drastically increasing airway pressure, suction during respiration, etc.). However, we could find no special advantages or disadvantages in ICP-course during long-term application of HFP (up to 10 days). Because application of HFV is dependent on special technical equipment, we investigated in 6 patients the influence of respiratory frequency, tidal volume and inspiratory flow on ICP-fluctuations using conventional ventilators. ICP was recorded by a new, self constructed pneumatic epidural pressure sensor. Ventilator-related ICP-fluctuations were found to be markedly reduced at frequencies of 20/min and usually eliminated at 30/min. We found an exponential correlation between ICP-fluctuations and respiratory frequency and there was no correlation between tidal volume and ICP. Central venous pressure amplitudes were found to be in linear correlation with respiratory frequency and tidal volumes as well. The amplitude of respiratory ICP-fluctuations seems to be more dependent on duration of expiratory time. As our findings demonstrate, artificial ventilation without entilator-related fluctuations in ICP ("brain-protective" ventilation) may be performed by conventional volume-constant, time-cycled ventilators.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of Heliox on Respiratory Outcomes during Rigid Bronchoscopy in Term Lambs.

PubMed

Sowder, Justin C; Dahl, Mar Janna; Zuspan, Kaitlin R; Albertine, Kurt H; Null, Donald M; Barneck, Mitchell D; Grimmer, J Fredrik

2018-03-01

Objective To (1) compare physiologic changes during rigid bronchoscopy during spontaneous and mechanical ventilation and (2) evaluate the efficacy of a helium-oxygen (heliox) gas mixture as compared with room air during rigid bronchoscopy. Study Design Crossover animal study evaluating physiologic parameters during rigid bronchoscopy. Outcomes were compared with predicted computational fluid analysis. Setting Simulated ventilation via computational fluid dynamics analysis and term lambs undergoing rigid bronchoscopy. Methods Respiratory and physiologic outcomes were analyzed in a lamb model simulating bronchoscopy during foreign body aspiration to compare heliox with room air. The main outcome measures were blood oxygen saturation, heart rate, blood pressure, partial pressure of oxygen, and partial pressure of carbon dioxide. Computational fluid dynamics analysis was performed with SOLIDWORKS within a rigid pediatric bronchoscope during simulated ventilation comparing heliox with room air. Results For room air, lambs desaturated within 3 minutes during mechanical ventilation versus normal oxygen saturation during spontaneous ventilation ( P = .01). No improvement in respiratory outcomes was seen between heliox and room air during mechanical ventilation. Computational fluid dynamics analysis demonstrates increased turbulence within size 3.5 bronchoscopes when comparing heliox and room air. Meaningful comparisons could not be made due to the intolerance of the lambs to heliox in vivo. Conclusion During mechanical ventilation on room air, lambs desaturate more quickly during rigid bronchoscopy on settings that should be adequate. Heliox does not improve ventilation during rigid bronchoscopy.

Tracheal gas insufflation combined with high-frequency oscillatory ventilation.

PubMed

Dolan, S; Derdak, S; Solomon, D; Farmer, C; Johanningman, J; Gelineau, J; Smith, R B

1996-03-01

To determine the efficacy of tracheal insufflation delivered by two different catheter designs on CO2 elimination when used in conjunction with high-frequency oscillatory ventilation. A nonrandomized before and after trial. Each animal served as his own control. Ten mongrel dogs weighing 20.9 +/- 1.9 kg. Four animals were assigned to a normal lung group and six animals underwent lung injury by large volume saline lavage. Permissive hypercapnia was allowed to occur by selecting oscillator settings that would lead to alveolar hypoventilation. Proximal mean airway pressure was kept constant. Tracheal gas was insufflated at 1 cm above the carina for 30 min periods at gas flows of 5 to 15 L/min. Carinal pressure, hemodynamic parameters (cardiac output, mean arterial pressure, pulmonary artery occlusion pressure), and gas exchange parameters (PaCO2, PaO2, PaO2/FIO2, shunt fraction, D O2) were measured. For the normal dogs, at catheter flow of 15 L/min; the forward thrust catheter increased carinal pressure and Pao2/FIO2 BY 30% (p<.003) and 105% (p<.005), respectively. The forward thrust catheter reduced Paco2 by 40% (p<.04). The reverse thrust catheter increased PaO2/FIO2 by 102% (p<.001) and decreased pressure and PaCO2 by 44% (p<.001) and 34% (p<.003), respectively. For the injured dogs, at catheter flow rate of 15 L/min, the forward thrust catheter increased carinal pressure, PaO2, and PaO2/FIO2 by 6% (p<.001), 23% (p<.001), and 24% (p<.02), respectively. The forward thrust catheter reduced PaCO2 by 29% (p<.002). The reverse thrust catheter increased PaO2 and PaO2/FIO2 both by 11% (p<.02) and reduced carinal pressure and PaCO2 by 23% (p<.001) and 18% (p<.002), respectively. Tracheal gas insufflation is capable of improving oxygenation and ventilation in acute lung injury when combined with high-frequency oscillatory ventilation. The addition of this second gas flow at the level of the carina raises or lowers distal airway pressure, the magnitude of which is dependent on the direction and rate of gas flow. The beneficial effects of tracheal gas insufflation may be tempered by the long-term effects of altering distal airway pressure; lowering distal airway pressure may lead to atelectasis, whereas raising distal airway pressure may lead to an auto-positive end-expiratory pressure (auto-PEEP) effect.

Retrospective Application of New Pediatric Ventilator-Associated Pneumonia Criteria Identifies a High-Risk Population.

PubMed

Gionfriddo, Ashley; Nonoyama, Mika L; Laussen, Peter C; Cox, Peter N; Clarke, Megan; Floh, Alejandro A

2018-06-01

To promote standardization, the Centers for Disease Control and Prevention introduced a new ventilator-associated pneumonia classification, which was modified for pediatrics (pediatric ventilator-associated pneumonia according to proposed criteria [PVAP]). We evaluated the frequency of PVAP in a cohort of children diagnosed with ventilator-associated pneumonia according to traditional criteria and compared their strength of association with clinically relevant outcomes. Retrospective cohort study. Tertiary care pediatric hospital. Critically ill children (0-18 yr) diagnosed with ventilator-associated pneumonia between January 2006 and December 2015 were identified from an infection control database. Patients were excluded if on high frequency ventilation, extracorporeal membrane oxygenation, or reintubated 24 hours following extubation. None. Patients were assessed for PVAP diagnosis. Primary outcome was the proportion of subjects diagnosed with PVAP. Secondary outcomes included association with intervals of care. Two hundred seventy-seven children who had been diagnosed with ventilator-associated pneumonia were eligible for review; 46 were excluded for being ventilated under 48 hours (n = 16), on high frequency ventilation (n = 12), on extracorporeal membrane oxygenation (n = 8), ineligible bacteria isolated from culture (n = 8), and other causes (n = 4). ICU admission diagnoses included congenital heart disease (47%), neurological (16%), trauma (7%), respiratory (7%), posttransplant (4%), neuromuscular (3%), and cardiomyopathy (3%). Only 16% of subjects (n = 45) met the new PVAP definition, with 18% (n = 49) having any ventilator-associated condition. Failure to fulfill new definitions was based on inadequate increase in mean airway pressure in 90% or FIO2 in 92%. PVAP was associated with prolonged ventilation (median [interquartile range], 29 d [13-51 d] vs 16 d [8-34.5 d]; p = 0.002), ICU (median [interquartile range], 40 d [20-100 d] vs 25 d [14-61 d]; p = 0.004) and hospital length of stay (median [interquartile range], 81 d [40-182 d] vs 54 d [31-108 d]; p = 0.04), and death (33% vs 16%; p = 0.008). Few children with ventilator-associated pneumonia diagnosis met the proposed PVAP criteria. PVAP was associated with increased morbidity and mortality. This work suggests that additional study is required before new definitions for ventilator-associated pneumonia are introduced for children.

Adherence to the items in a bundle for the prevention of ventilator-associated pneumonia.

PubMed

Sachetti, Amanda; Rech, Viviane; Dias, Alexandre Simões; Fontana, Caroline; Barbosa, Gilberto da Luz; Schlichting, Dionara

2014-01-01

To assess adherence to a ventilator care bundle in an intensive care unit and to determine the impact of adherence on the rates of ventilator-associated pneumonia. A total of 198 beds were assessed for 60 days using a checklist that consisted of the following items: bed head elevation to 30 to 45º; position of the humidifier filter; lack of fluid in the ventilator circuit; oral hygiene; cuff pressure; and physical therapy. Next, an educational lecture was delivered, and 235 beds were assessed for the following 60 days. Data were also collected on the incidence of ventilator-acquired pneumonia. Adherence to the following ventilator care bundle items increased: bed head elevation from 18.7% to 34.5%; lack of fluid in the ventilator circuit from 55.6% to 72.8%; oral hygiene from 48.5% to 77.8%; and cuff pressure from 29.8% to 51.5%. The incidence of ventilator-associated pneumonia was statistically similar before and after intervention (p=0.389). The educational intervention performed in this study increased the adherence to the ventilator care bundle, but the incidence of ventilator-associated pneumonia did not decrease in the small sample that was assessed.

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.

The effects of prone position ventilation in patients with acute respiratory distress syndrome. A systematic review and metaanalysis.

PubMed

Mora-Arteaga, J A; Bernal-Ramírez, O J; Rodríguez, S J

2015-01-01

Prone position ventilation has been shown to improve oxygenation and ventilatory mechanics in patients with acute respiratory distress syndrome. We evaluated whether prone ventilation reduces the risk of mortality in adult patients with acute respiratory distress syndrome versus supine ventilation. A metaanalysis of randomized controlled trials comparing patients in supine versus prone position was performed. A search was conducted of the Pubmed, Embase, Cochrane Library, and LILACS databases. Mortality, hospital length of stay, days of mechanical ventilation and adverse effects were evaluated. Seven randomized controlled trials (2,119 patients) were included in the analysis. The prone position showed a nonsignificant tendency to reduce mortality (OR: 0.76; 95%CI: 0.54 to 1.06; P=.11, I(2) 63%). When stratified by subgroups, a significant decrease was seen in the risk of mortality in patients ventilated with low tidal volume (OR: 0.58; 95%CI: 0.38 to 0.87; P=.009, I(2) 33%), prolonged pronation (OR: 0.6; 95%CI: 0.43 to 0.83; p=.002, I(2) 27%), start within the first 48hours of disease evolution (OR 0.49; 95%CI 0.35 to 0.68; P=.0001, I(2) 0%) and severe hypoxemia (OR: 0.51: 95%CI: 0.36 to 1.25; P=.0001, I(2) 0%). Adverse effects associated with pronation were the development of pressure ulcers and endotracheal tube obstruction. Prone position ventilation is a safe strategy and reduces mortality in patients with severely impaired oxygenation. It should be started early, for prolonged periods, and should be associated to a protective ventilation strategy. Copyright © 2014 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Association of center volume with outcomes in critically ill children with acute asthma.

PubMed

Gupta, Punkaj; Tang, Xinyu; Gossett, Jeffrey M; Gall, Christine M; Lauer, Casey; Rice, Tom B; Carroll, Christopher L; Kacmarek, Robert M; Wetzel, Randall C

2014-07-01

Little is known about the relation between center volume and outcomes in children requiring intensive care unit (ICU) admission for acute asthma. To evaluate the association of center volume with the odds of receiving positive pressure ventilation and length of ICU stay. Patients 2 to 18 years of age with the primary diagnosis of asthma were included (2009-2012). Center volume was defined as the average number of mechanical ventilator cases per year for any diagnoses during the study period. In multivariable analysis, the odds of receiving positive pressure ventilation (invasive and noninvasive ventilation) and ICU length of stay were evaluated as a function of center volume. Fifteen thousand eighty-three patients from 103 pediatric ICUs with the primary diagnosis of acute asthma met the inclusion criteria. Seven hundred fifty-two patients (5%) received conventional mechanical ventilation and 964 patients (6%) received noninvasive ventilation. In multivariable analysis, center volume was not associated with the odds of receiving any form of positive pressure ventilation in children with acute asthma, with the exception of high- to medium-volume centers. However, ICU length of stay varied with center volume and was noted to be longer in low-volume centers compared with medium- and high-volume centers. In children with acute asthma, this study establishes a relation between center volume and ICU length of stay. However, this study fails to show any significant relation between center volume and the odds of receiving positive pressure ventilation; further analyses are needed to evaluate this relation in more detail. Copyright © 2014 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

[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)

A novel fiber-optic measurement system for the evaluation of performances of neonatal pulmonary ventilators

NASA Astrophysics Data System (ADS)

Battista, L.; Scorza, A.; Botta, F.; Sciuto, S. A.

2016-02-01

Published standards for the performance evaluation of pulmonary ventilators are mainly directed to manufacturers rather than to end-users and often considered inadequate or not comprehensive. In order to contribute to overcome the problems above, a novel measurement system was proposed and tested with waveforms of mechanical ventilation by means of experimental trials carried out with infant ventilators typically used in neonatal intensive care units: the main quantities of mechanical ventilation in newborns are monitored, i.e. air flow rate, differential pressure and volume from infant ventilator are measured by means of two novel fiber-optic sensors (OFSs) developed and characterized by the authors, while temperature and relative humidity of air mass are obtained by two commercial transducers. The proposed fiber-optic sensors (flow sensor Q-OFS, pressure sensor P-OFS) showed measurement ranges of air flow and pressure typically encountered in neonatal mechanical ventilation, i.e. the air flow rate Q ranged from 3 l min-1 to 18 l min-1 (inspiratory) and from  -3 l min-1 to  -18 l min-1 (expiratory), the differential pressure ΔP ranged from  -15 cmH2O to 15 cmH2O. In each experimental trial carried out with different settings of the ventilator, outputs of the OFSs are compared with data from two reference sensors (reference flow sensor RF, reference pressure sensor RP) and results are found consistent: flow rate Q showed a maximum error between Q-OFS and RF up to 13 percent, with an output ratio Q RF/Q OFS of not more than 1.06  ±  0.09 (least square estimation, 95 percent confidence level, R 2 between 0.9822 and 0.9931). On the other hand the maximum error between P-OFS and RP on differential pressure ΔP was lower than 10 percent, with an output ratio ΔP RP/ΔP OFS between 0.977  ±  0.022 and 1.0  ±  0.8 (least square estimation, 95 percent confidence level, R 2 between 0.9864 and 0.9876). Despite the possible improvements, results were encouraging and suggested the proposed measurement system can be considered suitable for performances evaluation of neonatal ventilators and useful for both end-users and manufacturers.

Nasal mask ventilation is better than face mask ventilation in edentulous patients

PubMed Central

Kapoor, Mukul Chandra; Rana, Sandeep; Singh, Arvind Kumar; Vishal, Vindhya; Sikdar, Indranil

2016-01-01

Background and Aims: Face mask ventilation of the edentulous patient is often difficult as ineffective seating of the standard mask to the face prevents attainment of an adequate air seal. The efficacy of nasal ventilation in edentulous patients has been cited in case reports but has never been investigated. Material and Methods: Consecutive edentulous adult patients scheduled for surgery under general anesthesia with endotracheal intubation, during a 17-month period, were prospectively evaluated. After induction of anesthesia and administration of neuromuscular blocker, lungs were ventilated with a standard anatomical face mask of appropriate size, using a volume controlled anesthesia ventilator with tidal volume set at 10 ml/kg. In case of inadequate ventilation, the mask position was adjusted to achieve best-fit. Inspired and expired tidal volumes were measured. Thereafter, the face mask was replaced by a nasal mask and after achieving best-fit, the inspired and expired tidal volumes were recorded. The difference in expired tidal volumes and airway pressures at best-fit with the use of the two masks and number of patients with inadequate ventilation with use of the masks were statistically analyzed. Results: A total of 79 edentulous patients were recruited for the study. The difference in expiratory tidal volumes with the use of the two masks at best-fit was statistically significant (P = 0.0017). Despite the best-fit mask placement, adequacy of ventilation could not be achieved in 24.1% patients during face mask ventilation, and 12.7% patients during nasal mask ventilation and the difference was statistically significant. Conclusion: Nasal mask ventilation is more efficient than standard face mask ventilation in edentulous patients. PMID:27625477

Standardized application of laxatives and physical measures in neurosurgical intensive care patients improves defecation pattern but is not associated with lower intracranial pressure.

PubMed

Kieninger, Martin; Sinner, Barbara; Graf, Bernhard; Grassold, Astrid; Bele, Sylvia; Seemann, Milena; Künzig, Holger; Zech, Nina

2014-01-01

Background. Inadequate bowel movements might be associated with an increase in intracranial pressure in neurosurgical patients. In this study we investigated the influence of a structured application of laxatives and physical measures following a strict standard operating procedure (SOP) on bowel movement, intracranial pressure (ICP), and length of hospital stay in patients with a serious acute cerebral disorder. Methods. After the implementation of the SOP patients suffering from a neurosurgical disorder received pharmacological and nonpharmacological measures to improve bowel movements in a standardized manner within the first 5 days after admission to the intensive care unit (ICU) starting on day of admission. We compared mean ICP levels, length of ICU stay, and mechanical ventilation to a historical control group. Results. Patients of the intervention group showed an adequate defecation pattern significantly more often than the patients of the control group. However, this was not associated with lower ICP values, fewer days of mechanical ventilation, or earlier discharge from ICU. Conclusions. The implementation of a SOP for bowel movement increases the frequency of adequate bowel movements in neurosurgical critical care patients. However, this seems not to be associated with reduced ICP values.

Phosphotyrosine phosphatase and tyrosine kinase inhibition modulate airway pressure-induced lung injury.

PubMed

Parker, J C; Ivey, C L; Tucker, A

1998-11-01

We determined whether drugs which modulate the state of protein tyrosine phosphorylation could alter the threshold for high airway pressure-induced microvascular injury in isolated perfused rat lungs. Lungs were ventilated for successive 30-min periods with peak inflation pressures (PIP) of 7, 20, 30, and 35 cmH2O followed by measurement of the capillary filtration coefficient (Kfc), a sensitive index of hydraulic conductance. In untreated control lungs, Kfc increased by 1.3- and 3.3-fold relative to baseline (7 cmH2O PIP) after ventilation with 30 and 35 cmH2O PIP. However, in lungs treated with 100 microM phenylarsine oxide (a phosphotyrosine phosphatase inhibitor), Kfc increased by 4.7- and 16.4-fold relative to baseline at these PIP values. In lungs treated with 50 microM genistein (a tyrosine kinase inhibitor), Kfc increased significantly only at 35 cmH2O PIP, and the three groups were significantly different from each other. Thus phosphotyrosine phosphatase inhibition increased the susceptibility of rat lungs to high-PIP injury, and tyrosine kinase inhibition attenuated the injury relative to the high-PIP control lungs.

Preventing facial pressure ulcers in patients under non-invasive mechanical ventilation: a randomised control trial.

PubMed

Otero, D Peña; Domínguez, D Vazquez; Fernández, L Hernanz; Magariño, A Santano; González, V Jimenez; Klepzing, J V García; Montesinos, J V Beneit

2017-03-02

To comparatively assess the efficacy of four different therapeutic strategies to prevent the development of facial pressure ulcers (FPUs) related to the use of non-invasive mechanical ventilation (NIV) with oro-nasal masks in critically ill hospitalised patients. This randomised control trial was performed at the high dependency unit in the University General Hospital Gregorio Marañón in Madrid, Spain. Overall, 152 patients with acute respiratory failure were recruited. All patients were hospitalised and received NIV through oro-nasal masks. The Norton tool was used to evaluate the general risk of developing pressure ulcers (PUs). Subjects were divided into four groups, each of them receiving a different treatment. Tissue assessment and preventive care were performed by a member of the research team. The incidence of FPUs was significantly lower in the group receiving a solution of hyperoxygenated fatty acids (HOFA) when compared with each of the other therapeutic strategies: direct mask (p=0.055), adhesive thin dressing (p=0.03) and adhesive foam dressing (p<0.001). The application of HOFA on the facial skin in contact with the oro-nasal masks showed the highest efficacy in the prevention of NIV-related FPUs.

Respiratory diagnostic possibilities during closed circuit anesthesia.

PubMed

Verkaaik, A P; Erdmann, W

1990-01-01

An automatic feed back controlled totally closed circuit system (Physioflex) has been developed for quantitative practice of inhalation anesthesia and ventilation. In the circuit system the gas is moved unidirectionally around by a blower at 70 l/min. In the system four membrane chambers are integrated for ventilation. Besides end-expiratory feed back control of inhalation anesthetics, and inspiratory closed loop control of oxygen, the system offers on-line registration of flow, volume and respiratory pressures as well as a capnogram and oxygen consumption. Alveolar ventilation and static compliance can easily be derived. On-line registration of oxygen consumption has proven to be of value for determination of any impairment of tissue oxygen supply when the oxygen delivery has dropped to critical values. Obstruction of the upper or lower airways are immediately detected and differentiated. Disregulations of metabolism, e.g. in malignant hyperthermia, are seen in a pre-crisis phase (increase of oxygen consumption and of CO2 production), and therapy can be started extremely early and before a disastrous condition has developed. Registration of compliance is only one of the continuously available parameters that guarantee a better and adequate control of lung function (e.g. atalectasis is early detected). The newly developed sophisticated anesthesia device enlarges tremendously the monitoring and respiratory diagnostic possibilities of artificial ventilation, gives new insights in the (patho)physiology and detects disturbances of respiratory parameters and metabolism in an early stage.

Orotracheal tube as a risk factor for lower respiratory tract infection: preliminary data from a randomised trial.

PubMed

Muzlovic, Igor; Perme, Janja; Stubljar, David

2018-05-01

The aim of the study was to investigate whether polyurethane (PU) endotracheal tubes, continuous measurements of cuff pressure and aspiration of the subglottic space as a bundle of parameters could reduce patients' risk for developing ventilator associated pneumonia (VAP). Two groups of patients that differed only in terms of endotracheal tubes and intubation intervention were compared. Group A was ventilated using PU tubes a with conical cuff; they also had continuous cuff pressure measurement and continuous subglottic aspiration. Group B was ventilated using PVC tubes with a cylindrical cuff; the patients underwent intermittent cuff pressure measurement and intermittent subglottic aspiration. Seven patients in group A (13.2%) and 18 in group B (36.0%) out of 103 were diagnosed with VAP. VAP patients were in general older, stayed longer in the ICU and were ventilated significantly longer compared with the patients with no VAP. Eight more patients in group B died compared with group A. Moreover, subjects in group A survived longer. Patient age, hours on mechanical ventilation, and days on an ICU were all positively associated with the occurrence of VAP. Prevention parameters in ventilation (PU cuff, conical cuff, continuous subglottic drainage and continuous cuff pressure measurement) could prevent the incidence of VAP in ICU patients.

Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

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

Rudd, Armin; Bergey, Daniel

In this project, Building America research team Building Science Corporation tested the effectiveness of ventilation systems at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. This was because the sourcemore » of outside air was not direct from outside, the ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four system factor categories: balance, distribution, outside air source, and recirculation filtration. Recommended system factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.« less

Ventilation System Effectiveness and Tested Indoor Air Quality Impacts

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

Rudd, Armin; Bergey, Daniel

Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy. It was inferior because the source of outside air was not direct from outside, themore » ventilation air was not distributed, and no provision existed for air filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, and filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year.« less

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.

Sniffing position combined with mouth opening improves facemask ventilation in children with adenotonsillar hypertrophy.

PubMed

Cuvas, O; Dikmen, B; Yucel, F

2011-05-01

This study evaluates the influence of sniffing position combined with mouth opening on the effectiveness of facemask ventilation in paralyzed pediatric patients undergoing adenotonsillectomy during sevoflurane-N(2)O anesthesia. After Institutional Ethics Committee approval, 40 children 5-11 years of age who were scheduled for an elective adenotonsillectomy operation were enrolled in this prospective randomized study. After routine monitoring and pre-oxygenation, anesthesia was induced with sevoflurane 8% in a mixture of 50% N(2)O-O(2). Three minutes after the administration of vecuronium, the sequence of the positions was randomized. Three positions were applied during facemask ventilation: Position CN (closed mouth - neutral head and neck position), position CS (closed mouth-sniffing position) and position OS (opened mouth-sniffing position). Volume-controlled ventilation was started. Peak inspiratory pressure (PIP), tidal volume (V(T)), expired tidal volume (V(Texp)) and end-tidal CO(2) pressure were recorded. The percent of leakage was calculated. The primary endpoint of this study was the expired tidal volume (V(Texp)). There was a statistically significant difference among the three positions for V(Texp) and PIP values. The OS resulted in higher V(Texp) values when compared with CN (P=0.022). The OS was significantly better than the other two positions, resulting in lower PIP values (P<0.001 and P=0.004, for CN and CS, respectively). The OS also resulted in less leakage during facemask ventilation when compared with CN and CS. Sniffing position combined with mouth opening improves V(Texp) and PIP values during facemask ventilation during sevoflurane-N(2)O anesthesia in paralyzed pediatric patients with adenotonsillar hypertrophy.

Quantifying the Arousal Threshold Using Polysomnography in Obstructive Sleep Apnea.

PubMed

Sands, Scott A; Terrill, Philip I; Edwards, Bradley A; Taranto Montemurro, Luigi; Azarbarzin, Ali; Marques, Melania; de Melo, Camila M; Loring, Stephen H; Butler, James P; White, David P; Wellman, Andrew

2018-01-01

Precision medicine for obstructive sleep apnea (OSA) requires noninvasive estimates of each patient's pathophysiological "traits." Here, we provide the first automated technique to quantify the respiratory arousal threshold-defined as the level of ventilatory drive triggering arousal from sleep-using diagnostic polysomnographic signals in patients with OSA. Ventilatory drive preceding clinically scored arousals was estimated from polysomnographic studies by fitting a respiratory control model (Terrill et al.) to the pattern of ventilation during spontaneous respiratory events. Conceptually, the magnitude of the airflow signal immediately after arousal onset reveals information on the underlying ventilatory drive that triggered the arousal. Polysomnographic arousal threshold measures were compared with gold standard values taken from esophageal pressure and intraoesophageal diaphragm electromyography recorded simultaneously (N = 29). Comparisons were also made to arousal threshold measures using continuous positive airway pressure (CPAP) dial-downs (N = 28). The validity of using (linearized) nasal pressure rather than pneumotachograph ventilation was also assessed (N = 11). Polysomnographic arousal threshold values were correlated with those measured using esophageal pressure and diaphragm EMG (R = 0.79, p < .0001; R = 0.73, p = .0001), as well as CPAP manipulation (R = 0.73, p < .0001). Arousal threshold estimates were similar using nasal pressure and pneumotachograph ventilation (R = 0.96, p < .0001). The arousal threshold in patients with OSA can be estimated using polysomnographic signals and may enable more personalized therapeutic interventions for patients with a low arousal threshold. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

Technology Solutions Case Study: Air Leakage and Air Transfer Between Garage and Living Space, Waldorf, Maryland

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

None

2014-11-01

In this project, Building Science Corporation worked with production homebuilder K. Hovnanian to evaluate air transfer between the garage and living space in a single-family detached home constructed by a production homebuilder in compliance with the 2009 International Residential Code and the 2009 International Energy Conservation Code. The project gathered important information about the performance of whole-building ventilation systems and garage ventilation systems as they relate to minimizing flow of contaminated air from garage to living space. A series of 25 multipoint fan pressurization tests and additional zone pressure diagnostic testing measured the garage and house air leakage, the garage-to-housemore » air leakage, and garage and house pressure relationships to each other and to outdoors using automated fan pressurization and pressure monitoring techniques. While the relative characteristics of this house may not represent the entire population of new construction configurations and air tightness levels (house and garage) throughout the country, the technical approach was conservative and should reasonably extend the usefulness of the results to a large spectrum of house configurations from this set of parametric tests in this one house. Based on the results of this testing, the two-step garage-to-house air leakage test protocol described above is recommended where whole-house exhaust ventilation is employed. For houses employing whole-house supply ventilation (positive pressure) or balanced ventilation (same pressure effect as the baseline condition), adherence to the EPA Indoor airPLUS house-to-garage air sealing requirements should be sufficient to expect little to no garage-to-house air transfer.« less

Effect of water immersion on cardiopulmonary physiology at high gravity (+Gz)

NASA Technical Reports Server (NTRS)

Arieli, R.; Boutellier, U.; Farhi, L. E.

1986-01-01

The cardiopulmonary responses of eight male subject between 21-31 years exposed to 1, 2, and 3 Gz during immersion at 35 + or - 0.5 C to heart level and during control dry rides are studied. Ventilation, O2 consumption, the end-tidal pressure of CO2, heart frequency, cardiac output, functional residual capacity, and the arterial pressure of CO2 were measured. It is observed that as Gz increases ventilation, heart frequency, and O2 consumption increase, and the end-tidal and arterial pressures of CO2 decrease during dry rides, but are not altered during immersion. It is detected that the functional residual capacity is lower during immersion and decreases in both the dry and immersed state as Gz increases, and cardiac output decreases as Gz increases in dry rides. It is noted that changes produced by acceleration in a Gz direction are due to the effect on the systemic circulation rather than to the effect on the lungs.

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.

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.

Associations between ventilator settings during extracorporeal membrane oxygenation for refractory hypoxemia and outcome in patients with acute respiratory distress syndrome: a pooled individual patient data analysis : Mechanical ventilation during ECMO.

PubMed

Serpa Neto, Ary; Schmidt, Matthieu; Azevedo, Luciano C P; Bein, Thomas; Brochard, Laurent; Beutel, Gernot; Combes, Alain; Costa, Eduardo L V; Hodgson, Carol; Lindskov, Christian; Lubnow, Matthias; Lueck, Catherina; Michaels, Andrew J; Paiva, Jose-Artur; Park, Marcelo; Pesenti, Antonio; Pham, Tài; Quintel, Michael; Marco Ranieri, V; Ried, Michael; Roncon-Albuquerque, Roberto; Slutsky, Arthur S; Takeda, Shinhiro; Terragni, Pier Paolo; Vejen, Marie; Weber-Carstens, Steffen; Welte, Tobias; Gama de Abreu, Marcelo; Pelosi, Paolo; Schultz, Marcus J

2016-11-01

Extracorporeal membrane oxygenation (ECMO) is a rescue therapy for patients with acute respiratory distress syndrome (ARDS). The aim of this study was to evaluate associations between ventilatory settings during ECMO for refractory hypoxemia and outcome in ARDS patients. In this individual patient data meta-analysis of observational studies in adult ARDS patients receiving ECMO for refractory hypoxemia, a time-dependent frailty model was used to determine which ventilator settings in the first 3 days of ECMO had an independent association with in-hospital mortality. Nine studies including 545 patients were included. Initiation of ECMO was accompanied by significant decreases in tidal volume size, positive end-expiratory pressure (PEEP), plateau pressure, and driving pressure (plateau pressure - PEEP) levels, and respiratory rate and minute ventilation, and resulted in higher PaO 2 /FiO 2 , higher arterial pH and lower PaCO 2 levels. Higher age, male gender and lower body mass index were independently associated with mortality. Driving pressure was the only ventilatory parameter during ECMO that showed an independent association with in-hospital mortality [adjusted HR, 1.06 (95 % CI, 1.03-1.10)]. In this series of ARDS patients receiving ECMO for refractory hypoxemia, driving pressure during ECMO was the only ventilator setting that showed an independent association with in-hospital mortality.

Response of Preterm Infants to 2 Noninvasive Ventilatory Support Systems: Nasal CPAP and Nasal Intermittent Positive-Pressure Ventilation.

PubMed

Silveira, Carmen Salum Thomé; Leonardi, Kamila Maia; Melo, Ana Paula Carvalho Freire; Zaia, José Eduardo; Brunherotti, Marisa Afonso Andrade

2015-12-01

Noninvasive ventilation (NIV) in preterm infants is currently applied using intermittent positive pressure (2 positive-pressure levels) or in a conventional manner (one pressure level). However, there are no studies in the literature comparing the chances of failure of these NIV methods. The aim of this study was to evaluate the occurrence of failure of 2 noninvasive ventilatory support systems in preterm neonates over a period of 48 h. A randomized, prospective, clinical study was conducted on 80 newborns (gestational age < 37 weeks, birthweight < 2,500 g). The infants were randomized into 2 groups: 40 infants were treated with nasal CPAP and 40 infants with nasal intermittent positive-pressure ventilation (NIPPV). The occurrence of apnea, progression of respiratory distress, nose bleeding, and agitation was defined as ventilation failure. The need for intubation and re-intubation after failure was also observed. There were no significant differences in birth characteristics between groups. Ventilatory support failure was observed in 25 (62.5%) newborns treated with nasal CPAP and in 12 (30%) newborns treated with NIPPV, indicating an association between NIV failure and the absence of intermittent positive pressure (odds ratio [OR] 1.22, P < .05). Apnea (32.5%) was the main reason for nasal CPAP failure. After failure, 25% (OR 0.33) of the newborns receiving nasal CPAP and 12.5% (OR 0.14) receiving NIPPV required invasive mechanical ventilation. Ventilatory support failure was significantly more frequent when nasal CPAP was used. Copyright © 2015 by Daedalus Enterprises.

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.

Use of a Supraglottic Airway to Relieve Ventilation-Impeding Gastric Insufflation During Emergency Airway Management in an Infant.

PubMed

Dodd, Kenneth W; Strobel, Ashley M; Driver, Brian E; Reardon, Robert F

2016-10-01

Positive-pressure bag-valve-mask ventilation during emergency airway management often results in significant gastric insufflation, which may impede adequate ventilation and oxygenation. Current-generation supraglottic airways have beneficial features, such as channels for gastric decompression while ventilation is ongoing. A 5-week-old female infant required resuscitation for hypoxemic respiratory failure caused by rhinovirus with pneumonia. Bag-valve-mask ventilation led to gastric insufflation that compromised ventilation, thereby interfering with intubation because of precipitous oxygen desaturation during laryngoscopy. A current-generation supraglottic airway (LMA Supreme; Teleflex Inc, Morrisville, NC) was used to facilitate gastric decompression while ventilation and oxygenation was ongoing. After gastric decompression, ventilation was markedly improved and the pulse oxygen saturation improved to 100%. Intubation was successful on the next attempt, without oxygen desaturation. Current-generation supraglottic airways have 3 distinct advantages compared with first-generation supraglottic airways, which make them better devices for emergency airway management: gastric decompression ports, conduits for intubation, and higher oropharyngeal leak pressures. Copyright © 2016 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.

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.

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.

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.

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

Investigation of induced recirculation during planned ventilation system maintenance

PubMed Central

Pritchard, C.J.; Scott, D.F.; Noll, J.D.; Voss, B.; Leonis, D.

2015-01-01

The Office of Mine Safety and Health Research (OMSHR) investigated ways to increase mine airflow to underground metal/nonmetal (M/NM) mine working areas to improve miners’ health and safety. One of those areas is controlled recirculation. Because the quantity of mine air often cannot be increased, reusing part of the ventilating air can be an effective alternative, if implemented properly, until the capacity of the present system is improved. The additional airflow can be used to provide effective dilution of contaminants and higher flow velocities in the underground mine environment. Most applications of controlled recirculation involve taking a portion of the return air and passing it back into the intake to increase the air volume delivered to the desired work areas. OMSHR investigated a Nevada gold mine where shaft rehabilitation was in progress and one of the two main fans was shut down to allow reduced air velocity for safe shaft work. Underground booster fan operating pressures were kept constant to maintain airflow to work areas, inducing controlled recirculation in one work zone. Investigation into system behavior and the effects of recirculation on the working area during times of reduced primary ventilation system airflow would provide additional information on implementation of controlled recirculation into the system and how these events affect M/NM ventilation systems. The National Institute for Occupational Safety and Health monitored the ventilation district when both main fans were operating and another scenario with one of the units turned off for maintenance. Airflow and contaminants were measured to determine the exposure effects of induced recirculation on miner health. Surveys showed that 19% controlled recirculation created no change in the overall district airflow distribution and a small reduction in district fresh air intake. Total dust levels increased only modestly and respirable dust levels were also low. Diesel particulate matter (DPM) levels showed a high increase in district intake mass flow, but minor increases in exposure levels related to the recirculation percentage. Utilization of DPM mass flow rates allows input into ventilation modeling programs to better understand and plan for ventilation changes and district recirculation effects on miners’ health. PMID:26190862

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.

Mechanical ventilation management during extracorporeal membrane oxygenation for acute respiratory distress syndrome: a retrospective international multicenter study.

PubMed

Schmidt, Matthieu; Stewart, Claire; Bailey, Michael; Nieszkowska, Ania; Kelly, Joshua; Murphy, Lorna; Pilcher, David; Cooper, D James; Scheinkestel, Carlos; Pellegrino, Vincent; Forrest, Paul; Combes, Alain; Hodgson, Carol

2015-03-01

To describe mechanical ventilation settings in adult patients treated for an acute respiratory distress syndrome with extracorporeal membrane oxygenation and assess the potential impact of mechanical ventilation settings on ICU mortality. Retrospective observational study. Three international high-volume extracorporeal membrane oxygenation centers. A total of 168 patients treated with extracorporeal membrane oxygenation for severe acute respiratory distress syndrome from January 2007 to January 2013. We analyzed the association between mechanical ventilation settings (i.e. plateau pressure, tidal volume, and positive end-expiratory pressure) on ICU mortality using multivariable logistic regression model and Cox-proportional hazards model. We obtained detailed demographic, clinical, daily mechanical ventilation settings and ICU outcome data. One hundred sixty-eight patients (41 ± 14 years old; PaO2/FIO2 67 ± 19 mm Hg) fulfilled our inclusion criteria. Median duration of extracorporeal membrane oxygenation and ICU stay were 10 days (6-18 d) and 28 days (16-42 d), respectively. Lower positive end-expiratory pressure levels and significantly lower plateau pressures during extracorporeal membrane oxygenation were used in the French center than in both Australian centers (23.9 ± 1.4 vs 27.6 ± 3.7 and 27.8 ± 3.6; p < 0.0001). Overall ICU mortality was 29%. Lower positive end-expiratory pressure levels (until day 7) and lower delivered tidal volume after 3 days on extracorporeal membrane oxygenation were associated with significantly higher mortality (p < 0.05). In multivariate analysis, higher positive end-expiratory pressure levels during the first 3 days of extracorporeal membrane oxygenation support were associated with lower mortality (odds ratio, 0.75; 95% CI, 0.64-0.88; p = 0.0006). Other independent predictors of ICU mortality included time between ICU admission and extracorporeal membrane oxygenation initiation, plateau pressure greater than 30 cm H2O before extracorporeal membrane oxygenation initiation, and lactate level on day 3 of extracorporeal membrane oxygenation support. Protective mechanical ventilation strategies were routinely used in high-volume extracorporeal membrane oxygenation centers. However, higher positive end-expiratory pressure levels during the first 3 days on extracorporeal membrane oxygenation support were independently associated with improved survival. Further prospective trials on the optimal mechanical ventilation strategy during extracorporeal membrane oxygenation support are warranted.

30 CFR 18.28 - Devices for pressure relief, ventilation, or drainage.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Devices for pressure relief, ventilation, or drainage. 18.28 Section 18.28 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES...

[Characteristics and factors associated with mortality in patients receiving mechanical ventilation: first Chilean multicenter study].

PubMed

Tomicic, Vinko; Espinoza, Mauricio; Andresen, Max; Molina, Jorge; Calvo, Mario; Ugarte, Héctor; Godoy, Jorge; Gálvez, Sergio; Maurelia, Juan Carlos; Delgado, Iris; Esteban, Andrés

2008-08-01

The outcome of mechanically ventilated patients can be influenced by factors such as the indication of mechanical ventilation (MV) and ventilator parameters. To describe the characteristics of patients receiving MV in Chilean critical care units. Prospective cohort of consecutive adult patients admitted to 19 intensive care units (ICU) from 9 Chilean cities who received MV for more than 12 hours between September lst, 2003, and September 28th, 2003. Demographic data, severity of illness, reason for the initiation of MV, ventilation modes and settings as well as weaning strategies were registered at the initiation and then, daily throughout the course of MV for up to 28 days. ICU and hospital mortality were recorded. Of 588 patients admitted, 156 (26.5%) received MV (57% males). Mean age and Simplified Acute Physiology Score-II (SAPS II) were 54.6+/-18 years and 40.6+/-16.4 points respectively The most common indications for MV were acute respiratory failure (71.1%) and coma (22.4%). Assist-control mode (71.6%) and synchronized intermittent mandatory ventilation (SIMV) (14,2%) were the most frequently used. T-tube was the main weaning strategy. Mean duration of MV and length of stay in ICU were 7.8+/-8.7 and 11.1+/- 14 days respectively. Overall ICU mortality was 33.9% (53 patients). The main factors independently associated with increased mortality were (1) SAPS II > or =60 points (Odds Ratio (OR), 10.5; 95% CI, 1.04-106.85) and (2) plateau pressure > or =30 cm H2O at second day (OR, 3.9; 95% CI, 1.17-12.97). Conditions present at the onset of MV and ventilator management were similar to those reported in the literature. Magnitude of multiorgan dysfunction and high plateau pressures are the most important factors associated with mortality.

Effect of driving pressure on mortality in ARDS patients during lung protective mechanical ventilation in two randomized controlled trials.

PubMed

Guérin, Claude; Papazian, Laurent; Reignier, Jean; Ayzac, Louis; Loundou, Anderson; Forel, Jean-Marie

2016-11-29

Driving pressure (ΔPrs) across the respiratory system is suggested as the strongest predictor of hospital mortality in patients with acute respiratory distress syndrome (ARDS). We wonder whether this result is related to the range of tidal volume (V T ). Therefore, we investigated ΔPrs in two trials in which strict lung-protective mechanical ventilation was applied in ARDS. Our working hypothesis was that ΔPrs is a risk factor for mortality just like compliance (Crs) or plateau pressure (Pplat,rs) of the respiratory system. We performed secondary analysis of data from 787 ARDS patients enrolled in two independent randomized controlled trials evaluating distinct adjunctive techniques while they were ventilated as in the low V T arm of the ARDSnet trial. For this study, we used V T , positive end-expiratory pressure (PEEP), Pplat,rs, Crs, ΔPrs, and respiratory rate recorded 24 hours after randomization, and compared them between survivors and nonsurvivors at day 90. Patients were followed for 90 days after inclusion. Cox proportional hazard modeling was used for mortality at day 90. If colinearity between ΔPrs, Crs, and Pplat,rs was verified, specific Cox models were used for each of them. Both trials enrolled 805 patients of whom 787 had day-1 data available, and 533 of these survived. In the univariate analysis, ΔPrs averaged 13.7 ± 3.7 and 12.8 ± 3.7 cmH 2 O (P = 0.002) in nonsurvivors and survivors, respectively. Colinearity between ΔPrs, Crs and Pplat,rs, which was expected as these variables are mathematically coupled, was statistically significant. Hazard ratios from the Cox models for day-90 mortality were 1.05 (1.02-1.08) (P = 0.005), 1.05 (1.01-1.08) (P = 0.008) and 0.985 (0.972-0.985) (P = 0.029) for ΔPrs, Pplat,rs and Crs, respectively. PEEP and V T were not associated with death in any model. When ventilating patients with low V T , ΔPrs is a risk factor for death in ARDS patients, as is Pplat,rs or Crs. As our data originated from trials from which most ARDS patients were excluded due to strict inclusion and exclusion criteria, these findings must be validated in independent observational studies in patients ventilated with a lung protective strategy. Clinicaltrials.gov NCT00299650 . Registered 6 March 2006 for the Acurasys trial. Clinicaltrials.gov NCT00527813 . Registered 10 September 2007 for the Proseva trial.

46 CFR 108.187 - Ventilation for brush type electric motors in classified spaces.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Ventilation for brush type electric motors in classified... Ventilation for brush type electric motors in classified spaces. Ventilation for brush type electric motors in classified locations must meet N.F.P.A. 496-1974 “Standard for Purged and Pressurized Enclosures for...

Benefits of Manometer in Non-Invasive Ventilatory Support.

PubMed

Lacerda, Rodrigo Silva; de Lima, Fernando Cesar Anastácio; Bastos, Leonardo Pereira; Fardin Vinco, Anderson; Schneider, Felipe Britto Azevedo; Luduvico Coelho, Yves; Fernandes, Heitor Gomes Costa; Bacalhau, João Marcus Ramos; Bermudes, Igor Matheus Simonelli; da Silva, Claudinei Ferreira; da Silva, Luiza Paterlini; Pezato, Rogério

2017-12-01

Introduction Effective ventilation during cardiopulmonary resuscitation (CPR) is essential to reduce morbidity and mortality rates in cardiac arrest. Hyperventilation during CPR reduces the efficiency of compressions and coronary perfusion. Problem How could ventilation in CPR be optimized? The objective of this study was to evaluate non-invasive ventilator support using different devices. The study compares the regularity and intensity of non-invasive ventilation during simulated, conventional CPR and ventilatory support using three distinct ventilation devices: a standard manual resuscitator, with and without airway pressure manometer, and an automatic transport ventilator. Student's t-test was used to evaluate statistical differences between groups. P values <.05 were regarded as significant. Peak inspiratory pressure during ventilatory support and CPR was significantly increased in the group with manual resuscitator without manometer when compared with the manual resuscitator with manometer support (MS) group or automatic ventilator (AV) group. The study recommends for ventilatory support the use of a manual resuscitator equipped with MS or AVs, due to the risk of reduction in coronary perfusion pressure and iatrogenic thoracic injury during hyperventilation found using manual resuscitator without manometer. Lacerda RS , de Lima FCA , Bastos LP , Vinco AF , Schneider FBA , Coelho YL , Fernandes HGC , Bacalhau JMR , Bermudes IMS , da Silva CF , da Silva LP , Pezato R . Benefits of manometer in non-invasive ventilatory support. Prehosp Disaster Med. 2017;32(6):615-620.

The effect of perfluorocarbon vapour on the measurement of respiratory tidal volume during partial liquid ventilation.

PubMed

Davies, M W; Dunster, K R

2000-08-01

During partial liquid ventilation perfluorocarbon vapour is present in the exhaled gases. The volumes of these gases are measured by pneumotachometers. Error in measuring tidal volumes will give erroneous measurement of lung compliance during partial liquid ventilation. We aim to compare measured tidal volumes with and without perfluorocarbon vapour using tidal volumes suitable for use in neonates. Tidal volumes were produced with a 100 ml calibration syringe from 20 to 100 ml and with a calibrated Harvard rodent ventilator from 2.5 to 20 ml. Control tidal volumes were drawn from a humidifier chamber containing water vapour and the PFC tidal volumes were drawn from a humidifier chamber containing water and perfluorocarbon (FC-77) vapour. Tidal volumes were measured by a fixed orifice, target, differential pressure flowmeter (VenTrak) or a hot-wire anenometer (Bear Cub) placed between the calibration syringe or ventilator and the humidifier chamber. All tidal volumes measured with perfluorocarbon vapour were increased compared with control (ANOVA p < 0.001 and post t-test p < 0.0001). Measured tidal volume increased from 7 to 16% with the fixed orifice type flow-meter, and from 35 to 41% with the hot-wire type. In conclusion, perfluorocarbon vapour flowing through pneumotachometers gives falsely high tidal volume measurements. Calculation of lung compliance must take into account the effect of perfluorocarbon vapour on the measurement of tidal volume.

Congenital central hypoventilation syndrome: diagnostic and management challenges.

PubMed

Kasi, Ajay S; Perez, Iris A; Kun, Sheila S; Keens, Thomas G

2016-01-01

Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder with failure of central control of breathing and of the autonomic nervous system function due to a mutation in the paired-like homeobox 2B (PHOX2B) gene. Affected patients have absent or negligible ventilatory sensitivity to hypercapnia and hypoxemia, and they do not exhibit signs of respiratory distress when challenged with hypercarbia or hypoxia. The diagnosis of CCHS must be confirmed with PHOX2B gene mutation. Generally, the PHOX2B mutation genotype can aid in anticipating the severity of the phenotype. They require ventilatory support for life. Home assisted ventilation options include positive pressure ventilation via tracheostomy, noninvasive positive pressure ventilation, and diaphragm pacing via phrenic nerve stimulation, but each strategy has its associated limitations and challenges. Since all the clinical manifestations of CCHS may not manifest at birth, periodic monitoring and early intervention are necessary to prevent complications and improve outcome. Life-threatening arrhythmias can manifest at different ages and a normal cardiac monitoring study does not exclude future occurrences leading to the dilemma of timing and frequency of cardiac rhythm monitoring and treatment. Given the rare incidence of CCHS, most health care professionals are not experienced with managing CCHS patients, particularly those with diaphragm pacers. With early diagnosis and advances in home mechanical ventilation and monitoring strategies, many CCHS children are surviving into adulthood presenting new challenges in their care.

Seasonal changes in the preferred body temperature, cardiovascular, and respiratory responses to hypoxia in the toad, Bufo paracnemis.

PubMed

Bícego-Nahas, K C; Gargaglioni, L H; Branco, L G

2001-05-01

Estivation is accompanied by a reduction of oxygen consumption in amphibians during drought. We tested the hypothesis that, during the dry season, the toad Bufo paracnemis selects a lower preferred body temperature (T(b)), and would be less sensitive to hypoxia, than during its active period. Therefore, during winter (dry season in São Paulo state, Brazil) and summer, we measured the effects of hypoxia (7% inspired O(2)) on preferred T(b). Additionally, pulmonary ventilation, heart rate, blood pressure, and oxygen consumption were also measured in toads at 15 and 25 degrees C. Blood gases were measured at 25 degrees C. Oxygen consumption was significantly higher during summer in toads at 25 degrees C. Under normoxia, preferred T(b) was higher during summer than during winter, and hypoxia caused a drop in preferred T(b) during both seasons. In both seasons, toads at 15 degrees C showed reduced pulmonary ventilation, heart rate, and blood pressure, and hypoxia had no effect. At 25 degrees C during summer only, hypoxia caused an increase in ventilation. Season had no effect on blood gases. We conclude that B. paracnemis displays an endogenous seasonal pattern of thermoregulation and control of ventilation. The decreased preferred T(b) and the physiological responses to hypoxia may be beneficial to toads encountering drought and when food is not available.

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

Miller, William A; Railkar, Sudhir; Shiao, Ming C

Field studies in a hot, humid climate were conducted to investigate the thermal and hygrothermal performance of ventilated attics and non-ventilated semi-conditioned attics sealed with open-cell and with closed-cell spray polyurethane foam insulation. Moisture pin measurements made in the sheathing and absolute humidity sensor data from inside the foam and from the attic air show that moisture is being stored in the foam. The moisture in the foam diffuses to and from the sheathing dependent on the pressure gradient at the foam-sheathing interface which is driven by the irradiance and night-sky radiation. Ventilated attics in the same hot, humid climatemore » showed less moisture movement in the sheathing than those sealed with either open- or closed-cell spray foam. In the ventilated attics the relative humidity drops as the attic air warms; however, the opposite was observed in the sealed attics. Peaks in measured relative humidity in excess of 80 90% and occasionally near saturation (i.e., 100%) were observed from solar noon till about 8 PM on hot, humid days. The conditioned space of the test facility is heated and cooled by an air-to-air heat pump. Therefore the partial pressure of the indoor air during peak irradiance is almost always less than that observed in the sealed attics. Field data will be presented to bring to light the critical humidity control issues in sealed attics exposed to hot, humid climates.« less

Characterization of Ventilatory Modes in Dragonfly Nymph

NASA Astrophysics Data System (ADS)

Roh, Chris; Saxton-Fox, Theresa; Gharib, Morteza

2013-11-01

A dragonfly nymph's highly modified hindgut has multiple ventilatory modes: hyperventilation (i.e. jet propulsion), gulping ventilation (extended expiratory phase) and normal ventilation. Each mode involves dynamic manipulation of the exit diameter and pressure. To study the different fluid dynamics associated with the three modes, Anisopteran larvae of the family Aeshnidae were tethered onto a rod for flow visualization. The result showed distinct flow structures. The hyperventilation showed a highly turbulent and powerful jet that occurred at high frequency. The gulping ventilation produced a single vortex at a moderate frequency. The normal ventilation showed two distinct vortices, a low-Reynolds number vortex, followed by a high-Reynolds number vortex. Furthermore, a correlation of the formation of the vortices with the movement of the sternum showed that the dragonfly is actively controlling the timing and the speed of the vortices to have them at equal distance from the jet exit at the onset of inspiration. This behavior prevents inspiration of the oxygen deficient expirated water, resulting in the maximization of the oxygen intake. Supported by NSF GRFP.

Association between ventilatory settings and development of acute respiratory distress syndrome in mechanically ventilated patients due to brain injury.

PubMed

Tejerina, Eva; Pelosi, Paolo; Muriel, Alfonso; Peñuelas, Oscar; Sutherasan, Yuda; Frutos-Vivar, Fernando; Nin, Nicolás; Davies, Andrew R; Rios, Fernando; Violi, Damian A; Raymondos, Konstantinos; Hurtado, Javier; González, Marco; Du, Bin; Amin, Pravin; Maggiore, Salvatore M; Thille, Arnaud W; Soares, Marco Antonio; Jibaja, Manuel; Villagomez, Asisclo J; Kuiper, Michael A; Koh, Younsuck; Moreno, Rui P; Zeggwagh, Amine Ali; Matamis, Dimitrios; Anzueto, Antonio; Ferguson, Niall D; Esteban, Andrés

2017-04-01

In neurologically critically ill patients with mechanical ventilation (MV), the development of acute respiratory distress syndrome (ARDS) is a major contributor to morbidity and mortality, but the role of ventilatory management has been scarcely evaluated. We evaluate the association of tidal volume, level of PEEP and driving pressure with the development of ARDS in a population of patients with brain injury. We performed a secondary analysis of a prospective, observational study on mechanical ventilation. We included 986 patients mechanically ventilated due to an acute brain injury (hemorrhagic stroke, ischemic stroke or brain trauma). Incidence of ARDS in this cohort was 3%. Multivariate analysis suggested that driving pressure could be associated with the development of ARDS (odds ratio for unit increment of driving pressure 1.12; confidence interval for 95%: 1.01 to 1.23) whereas we did not observe association for tidal volume (in ml per kg of predicted body weight) or level of PEEP. ARDS was associated with an increase in mortality, longer duration of mechanical ventilation, and longer ICU length of stay. In a cohort of brain-injured patients the development of ARDS was not common. Driving pressure was associated with the development of this disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Impact of Different Ventilation Strategies on Driving Pressure, Mechanical Power, and Biological Markers During Open Abdominal Surgery in Rats.

PubMed

Maia, Lígia de A; Samary, Cynthia S; Oliveira, Milena V; Santos, Cintia L; Huhle, Robert; Capelozzi, Vera L; Morales, Marcelo M; Schultz, Marcus J; Abreu, Marcelo G; Pelosi, Paolo; Silva, Pedro L; Rocco, Patricia Rieken Macedo

2017-10-01

Intraoperative mechanical ventilation may yield lung injury. To date, there is no consensus regarding the best ventilator strategy for abdominal surgery. We aimed to investigate the impact of the mechanical ventilation strategies used in 2 recent trials (Intraoperative Protective Ventilation [IMPROVE] trial and Protective Ventilation using High versus Low PEEP [PROVHILO] trial) on driving pressure (ΔPRS), mechanical power, and lung damage in a model of open abdominal surgery. Thirty-five Wistar rats were used, of which 28 were anesthetized, and a laparotomy was performed with standardized bowel manipulation. Postoperatively, animals (n = 7/group) were randomly assigned to 4 hours of ventilation with: (1) tidal volume (VT) = 7 mL/kg and positive end-expiratory pressure (PEEP) = 1 cm H2O without recruitment maneuvers (RMs) (low VT/low PEEP/RM-), mimicking the low-VT/low-PEEP strategy of PROVHILO; (2) VT = 7 mL/kg and PEEP = 3 cm H2O with RMs before laparotomy and hourly thereafter (low VT/moderate PEEP/4 RM+), mimicking the protective ventilation strategy of IMPROVE; (3) VT = 7 mL/kg and PEEP = 6 cm H2O with RMs only before laparotomy (low VT/high PEEP/1 RM+), mimicking the strategy used after intubation and before extubation in PROVHILO; or (4) VT = 14 mL/kg and PEEP = 1 cm H2O without RMs (high VT/low PEEP/RM-), mimicking conventional ventilation used in IMPROVE. Seven rats were not tracheotomized, operated, or mechanically ventilated, and constituted the healthy nonoperated and nonventilated controls. Low VT/moderate PEEP/4 RM+ and low VT/high PEEP/1 RM+, compared to low VT/low PEEP/RM- and high VT/low PEEP/RM-, resulted in lower ΔPRS (7.1 ± 0.8 and 10.2 ± 2.1 cm H2O vs 13.9 ± 0.9 and 16.9 ± 0.8 cm H2O, respectively; P< .001) and less mechanical power (63 ± 7 and 79 ± 20 J/min vs 110 ± 10 and 120 ± 20 J/min, respectively; P = .007). Low VT/high PEEP/1 RM+ was associated with less alveolar collapse than low VT/low PEEP/RM- (P = .03). E-cadherin expression was higher in low VT/moderate PEEP/4 RM+ than in low VT/low PEEP/RM- (P = .013) or high VT/low PEEP/RM- (P = .014). The extent of alveolar collapse, E-cadherin expression, and tumor necrosis factor-alpha correlated with ΔPRS (r = 0.54 [P = .02], r = -0.48 [P = .05], and r = 0.59 [P = .09], respectively) and mechanical power (r = 0.57 [P = .02], r = -0.54 [P = .02], and r = 0.48 [P = .04], respectively). In this model of open abdominal surgery based on the mechanical ventilation strategies used in IMPROVE and PROVHILO trials, lower mechanical power and its surrogate ΔPRS were associated with reduced lung damage.

Predictive value of pulse pressure variation for fluid responsiveness in septic patients using lung-protective ventilation strategies.

PubMed

Freitas, F G R; Bafi, A T; Nascente, A P M; Assunção, M; Mazza, B; Azevedo, L C P; Machado, F R

2013-03-01

The applicability of pulse pressure variation (ΔPP) to predict fluid responsiveness using lung-protective ventilation strategies is uncertain in clinical practice. We designed this study to evaluate the accuracy of this parameter in predicting the fluid responsiveness of septic patients ventilated with low tidal volumes (TV) (6 ml kg(-1)). Forty patients after the resuscitation phase of severe sepsis and septic shock who were mechanically ventilated with 6 ml kg(-1) were included. The ΔPP was obtained automatically at baseline and after a standardized fluid challenge (7 ml kg(-1)). Patients whose cardiac output increased by more than 15% were considered fluid responders. The predictive values of ΔPP and static variables [right atrial pressure (RAP) and pulmonary artery occlusion pressure (PAOP)] were evaluated through a receiver operating characteristic (ROC) curve analysis. Thirty-four patients had characteristics consistent with acute lung injury or acute respiratory distress syndrome and were ventilated with high levels of PEEP [median (inter-quartile range) 10.0 (10.0-13.5)]. Nineteen patients were considered fluid responders. The RAP and PAOP significantly increased, and ΔPP significantly decreased after volume expansion. The ΔPP performance [ROC curve area: 0.91 (0.82-1.0)] was better than that of the RAP [ROC curve area: 0.73 (0.59-0.90)] and pulmonary artery occlusion pressure [ROC curve area: 0.58 (0.40-0.76)]. The ROC curve analysis revealed that the best cut-off for ΔPP was 6.5%, with a sensitivity of 0.89, specificity of 0.90, positive predictive value of 0.89, and negative predictive value of 0.90. Automatized ΔPP accurately predicted fluid responsiveness in septic patients ventilated with low TV.

Air Leakage and Air Transfer Between Garage and Living Space

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

Rudd, A.

2014-09-01

This research project focused on evaluation of air transfer between the garage and living space in a single-family detached home constructed by a production homebuilder in compliance with the 2009 International Residential Code and the 2009 International Energy Conservation Code. The project gathered important information about the performance of whole-building ventilation systems and garage ventilation systems as they relate to minimizing flow of contaminated air from garage to living space. A series of 25 multi-point fan pressurization tests and additional zone pressure diagnostic testing characterized the garage and house air leakage, the garage-to-house air leakage, and garage and house pressuremore » relationships to each other and to outdoors using automated fan pressurization and pressure monitoring techniques. While the relative characteristics of this house may not represent the entire population of new construction configurations and air tightness levels (house and garage) throughout the country, the technical approach was conservative and should reasonably extend the usefulness of the results to a large spectrum of house configurations from this set of parametric tests in this one house. Based on the results of this testing, the two-step garage-to-house air leakage test protocol described above is recommended where whole-house exhaust ventilation is employed. For houses employing whole-house supply ventilation (positive pressure) or balanced ventilation (same pressure effect as the Baseline condition), adherence to the EPA Indoor airPLUS house-to-garage air sealing requirements should be sufficient to expect little to no garage-to-house air transfer.« less

Building America Case Study: Air Leakage and Air Transfer Between Garage and Living Space, Waldorf, Maryland (Fact Sheet)

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

Not Available

2014-11-01

This research project focused on evaluation of air transfer between the garage and living space in a single-family detached home constructed by a production homebuilder in compliance with the 2009 International Residential Code and the 2009 International Energy Conservation Code. The project gathered important information about the performance of whole-building ventilation systems and garage ventilation systems as they relate to minimizing flow of contaminated air from garage to living space. A series of 25 multi-point fan pressurization tests and additional zone pressure diagnostic testing characterized the garage and house air leakage, the garage-to-house air leakage, and garage and house pressuremore » relationships to each other and to outdoors using automated fan pressurization and pressure monitoring techniques. While the relative characteristics of this house may not represent the entire population of new construction configurations and air tightness levels (house and garage) throughout the country, the technical approach was conservative and should reasonably extend the usefulness of the results to a large spectrum of house configurations from this set of parametric tests in this one house. Based on the results of this testing, the two-step garage-to-house air leakage test protocol described above is recommended where whole-house exhaust ventilation is employed. For houses employing whole-house supply ventilation (positive pressure) or balanced ventilation (same pressure effect as the Baseline condition), adherence to the EPA Indoor airPLUS house-to-garage air sealing requirements should be sufficient to expect little to no garage-to-house air transfer.« less

Continuous High-Frequency Oscillation Therapy in Invasively Ventilated Pediatric Subjects in the Critical Care Setting.

PubMed

Morgan, Stephen; Hornik, Christoph P; Patel, Niyati; Williford, Walter L; Turner, David A; Cheifetz, Ira M

2016-11-01

Continuous high-frequency oscillation (CHFO) creates a pressure gradient in the small airways that accelerates expiratory flow. The intended use of CHFO therapy is to facilitate secretion removal and treat atelectasis. Our objective was to assess the feasibility, safety, and efficacy of CHFO in the mechanically ventilated pediatric population. After institutional review board approval, we retrospectively reviewed medical records of mechanically ventilated children treated with CHFO (the MetaNeb system) at our institution from July 1, 2007 through August 31, 2012. Patients supported with extracorporeal membrane oxygenation were excluded. We evaluated changes in ventilator settings in subjects with ventilator data documented within 6 h pre- and post-treatment. We evaluated arterial blood gas (ABG) results for individual treatments, comparing ABG results within 8 h pre-therapy to ABG results within 3 h post-treatment. Oxygen index and P aO 2 /F IO 2 were calculated. Demographic data, blood pressure, heart rate, and development of new air leak while being treated with CHFO were recorded. Pre- and post-CHFO measurements were compared using Wilcoxon signed-rank testing. Our cohort included 59 invasively ventilated subjects. Median age was 2 y (range 1 month to 19 y), and median weight was 14 kg (2-81 kg). We evaluated data on 528 total treatments (range per subject 1-39 treatments). Peak inspiratory pressure significantly decreased with CHFO, whereas other parameters, including P aCO 2 and breathing frequency, remained stable. There was no significant change in systolic blood pressure, diastolic blood pressure, or heart rate following treatment with CHFO. One subject (2%) developed a clinically insignificant pneumothorax during CHFO. CHFO is feasible and seems safe in our cohort of mechanically ventilated pediatric subjects. The rate of pneumothorax was consistent with that seen in similar pediatric ICU populations. These preliminary results suggest that CHFO may be beneficial by improving lung compliance in pediatric subjects with secretion-induced atelectasis. Prospective clinical studies are needed to further evaluate the clinical efficacy and safety of CHFO in children receiving invasive mechanical ventilation. Copyright © 2016 by Daedalus Enterprises.

Comparing effects between music intervention and aromatherapy on anxiety of patients undergoing mechanical ventilation in the intensive care unit: a randomized controlled trial.

PubMed

Lee, Chiu-Hsiang; Lai, Chiung-Ling; Sung, Yi-Hui; Lai, Mei Yu; Lin, Chung-Ying; Lin, Long-Yau

2017-07-01

Using patient-reported outcomes and physiological indicators to test the effects of music intervention and aromatherapy on reducing anxiety for intensive care unit (ICU) patients undergoing mechanical ventilation. Patients with ICU admission duration >24 h were randomly assigned to a Music intervention group (n = 41), Aromatherapy group (n = 47), or Control group (rest only; n = 44). Each patient in the Music group listened to music; each patient in the Aromatherapy group received lavender essential oil massage on his/her back for 5 min; each patient in the Control group wore noise-canceling headphones. Anxiety was measured using the Chinese version of the Stage-Trait Anxiety Inventory (C-STAI) and the Visual Analogue Scale for Anxiety (VAS-A) at baseline, post-test, and 30-min follow-up. Heart rate, breathing rate, and blood pressure were measured every 10 min from baseline to the 30-min follow-up. The Music group had significantly better post-test VAS-A and C-STAI scores, and had lower heart rate and blood pressure than the Control group. The Aromatherapy group had significantly better VAS-A score and lower heart rate than the Control group. The 30-min follow-up showed that both Music and Aromatherapy groups had lower heart rate and blood pressure than the Control group. Music and aromatherapy interventions were both effective for ICU patients. The effects of music intervention were greater than that of aromatherapy; both interventions maintained the effects for at least 30 min.

Early application of airway pressure release ventilation may reduce the duration of mechanical ventilation in acute respiratory distress syndrome.

PubMed

Zhou, Yongfang; Jin, Xiaodong; Lv, Yinxia; Wang, Peng; Yang, Yunqing; Liang, Guopeng; Wang, Bo; Kang, Yan

2017-11-01

Experimental animal models of acute respiratory distress syndrome (ARDS) have shown that the updated airway pressure release ventilation (APRV) methodologies may significantly improve oxygenation, maximize lung recruitment, and attenuate lung injury, without circulatory depression. This led us to hypothesize that early application of APRV in patients with ARDS would allow pulmonary function to recover faster and would reduce the duration of mechanical ventilation as compared with low tidal volume lung protective ventilation (LTV). A total of 138 patients with ARDS who received mechanical ventilation for <48 h between May 2015 to October 2016 while in the critical care medicine unit (ICU) of the West China Hospital of Sichuan University were enrolled in the study. Patients were randomly assigned to receive APRV (n = 71) or LTV (n = 67). The settings for APRV were: high airway pressure (P high ) set at the last plateau airway pressure (P plat ), not to exceed 30 cmH 2 O) and low airway pressure ( P low ) set at 5 cmH 2 O; the release phase (T low ) setting adjusted to terminate the peak expiratory flow rate to ≥ 50%; release frequency of 10-14 cycles/min. The settings for LTV were: target tidal volume of 6 mL/kg of predicted body weight; P plat not exceeding 30 cmH 2 O; positive end-expiratory pressure (PEEP) guided by the PEEP-FiO 2 table according to the ARDSnet protocol. The primary outcome was the number of days without mechanical ventilation from enrollment to day 28. The secondary endpoints included oxygenation, P plat , respiratory system compliance, and patient outcomes. Compared with the LTV group, patients in the APRV group had a higher median number of ventilator-free days {19 [interquartile range (IQR) 8-22] vs. 2 (IQR 0-15); P < 0.001}. This finding was independent of the coexisting differences in chronic disease. The APRV group had a shorter stay in the ICU (P = 0.003). The ICU mortality rate was 19.7% in the APRV group versus 34.3% in the LTV group (P = 0.053) and was associated with better oxygenation and respiratory system compliance, lower P plat , and less sedation requirement during the first week following enrollment (P < 0.05, repeated-measures analysis of variance). Compared with LTV, early application of APRV in patients with ARDS improved oxygenation and respiratory system compliance, decreased P plat and reduced the duration of both mechanical ventilation and ICU stay.

Comparison of postoperative complication between Laryngeal Mask Airway and endotracheal tube during low-flow anesthesia with controlled ventilation

PubMed Central

Peirovifar, Ali; Eydi, Mahmood; Mirinejhad, Mir Mousa; Mahmoodpoor, Ata; Mohammadi, Afsaneh; EJ Golzari, Samad

2013-01-01

Objective: To compare the postoperative complications between Laryngeal Mask Airway (LMA) and endotracheal tube (ETT) during low-flow anesthesia with controlled ventilation. Methodology: Eighty adult Patients with ASA class I or II were randomly allocated into two forty-patient groups (ETT or LMA). Cuff pressure was monitored during anesthesia. After high uptake period, fresh gas flow (FGF) was decreased to 1 lit/min and isoflurane set to 1%. Monitoring during anesthesia included non-invasive blood pressure, ECG, ETCO2 and pulse oximetry. System leakage (>100 ml/min), rebreathing and any attempt to increase FGF to overcome the leak were monitored during anesthesia. Later, patients were extubated and transferred to Post Anesthesia Care Unit (PACU). In PACU, the incidence of sore throat, cough, difficulty in swallowing and shivering was monitored for all patients. Results: Leakage was observed in two and three cases in ETT and LMA groups respectively (P>0.05). Postoperative cough, sore throat and difficulty in swallowing were significantly less in LMA than ETT group. No significant difference was observed regarding ETCo2 values between 2 groups. Conclusion: If careful measures regarding insertion techniques, correct LMA position and routine monitoring of LMA cuff pressure are taken, LMA can be used as a safe alternative with lower incidence of post operation complication compared with ETT during low-flow controlled anesthesia with modern anesthetic machines. PMID:24353586

Respiratory training during rehabilitation of acute organic fluorine-poisoned patients treated by non-invasive positive pressure ventilation.

PubMed

Liu, L; Liu, D Z; Wang, Q P; Zhu, Z L; Li, H M; Lu, X Y

2017-01-01

This paper aimed to analyze the effects of respiratory training on pulmonary function during the rehabilitation period for acute organic fluorine-poisoned patients treated by non-invasive positive pressure ventilation (NIPPV). Sixty-two acute organic fluorine-poisoned patients admitted to the Xinxiang Central Hospital, Xinxiang City, China, from May 2012 to March 2016 were selected and randomly divided into an observation group and a control group, with 31 cases in each. Both groups received NIPPV. The patients in the control group exercised daily, while the patients in the observation group received contracting lips-abdominal breathing training. The therapeutic effects, pulmonary ventilation function, serum levels of α-antitrypsin1 (α-AT1), surfactant protein D (SP-D), neutrophil elastase (NE), transforming growth factor beta 1 (TGF-β1), and quality of life were analyzed and compared between the two groups both before and after the administration of treatment. The total effective rate of the observation group was 93.55%, which was significantly higher when compared with the control group (74.19%) (P less than 0.05). The levels of forced expiratory volume in one second (FEV1), FEV1/FVC ratio, vital capacity (VC), carbon monoxide diffusion capacity (DLco), and maximal voluntary ventilation (MVV) of the observation group were better when compared with the control group and had statistical significance (P less than 0.05). Before treatment, the serum levels of α-AT1, SP-D, NE, and TGF-β1, and quality of life had no statistical significance in either group (P>0.05); after treatment, these indexes and the quality of life for the observation group were significantly higher when compared with the control group, with statistical significance (P less than 0.05). The respiratory training in acute organic fluorine-poisoned patients treated by NIPPV can improve the serum indexes, dilute toxicity, and recover pulmonary function, which play key roles in improving the therapeutic effects and quality of life of patients, and is worthy of clinical promotion.

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): study protocol for a randomized controlled trial.

PubMed

2012-08-28

Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH2O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure ≤30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method. ClinicalTrials.gov Identifier: NCT01374022.

Rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART): Study protocol for a randomized controlled trial

PubMed Central

2012-01-01

Background Acute respiratory distress syndrome (ARDS) is associated with high in-hospital mortality. Alveolar recruitment followed by ventilation at optimal titrated PEEP may reduce ventilator-induced lung injury and improve oxygenation in patients with ARDS, but the effects on mortality and other clinical outcomes remain unknown. This article reports the rationale, study design, and analysis plan of the Alveolar Recruitment for ARDS Trial (ART). Methods/Design ART is a pragmatic, multicenter, randomized (concealed), controlled trial, which aims to determine if maximum stepwise alveolar recruitment associated with PEEP titration is able to increase 28-day survival in patients with ARDS compared to conventional treatment (ARDSNet strategy). We will enroll adult patients with ARDS of less than 72 h duration. The intervention group will receive an alveolar recruitment maneuver, with stepwise increases of PEEP achieving 45 cmH2O and peak pressure of 60 cmH2O, followed by ventilation with optimal PEEP titrated according to the static compliance of the respiratory system. In the control group, mechanical ventilation will follow a conventional protocol (ARDSNet). In both groups, we will use controlled volume mode with low tidal volumes (4 to 6 mL/kg of predicted body weight) and targeting plateau pressure ≤30 cmH2O. The primary outcome is 28-day survival, and the secondary outcomes are: length of ICU stay; length of hospital stay; pneumothorax requiring chest tube during first 7 days; barotrauma during first 7 days; mechanical ventilation-free days from days 1 to 28; ICU, in-hospital, and 6-month survival. ART is an event-guided trial planned to last until 520 events (deaths within 28 days) are observed. These events allow detection of a hazard ratio of 0.75, with 90% power and two-tailed type I error of 5%. All analysis will follow the intention-to-treat principle. Discussion If the ART strategy with maximum recruitment and PEEP titration improves 28-day survival, this will represent a notable advance to the care of ARDS patients. Conversely, if the ART strategy is similar or inferior to the current evidence-based strategy (ARDSNet), this should also change current practice as many institutions routinely employ recruitment maneuvers and set PEEP levels according to some titration method. Trial registration ClinicalTrials.gov Identifier: NCT01374022 PMID:22929542

Non-lobar atelectasis generates inflammation and structural alveolar injury in the surrounding healthy tissue during mechanical ventilation.

PubMed

Retamal, Jaime; Bergamini, Bruno Curty; Carvalho, Alysson R; Bozza, Fernando A; Borzone, Gisella; Borges, João Batista; Larsson, Anders; Hedenstierna, Göran; Bugedo, Guillermo; Bruhn, Alejandro

2014-09-09

When alveoli collapse the traction forces exerted on their walls by adjacent expanded units may increase and concentrate. These forces may promote its re-expansion at the expense of potentially injurious stresses at the interface between the collapsed and the expanded units. We developed an experimental model to test the hypothesis that a local non-lobar atelectasis can act as a stress concentrator, contributing to inflammation and structural alveolar injury in the surrounding healthy lung tissue during mechanical ventilation. A total of 35 rats were anesthetized, paralyzed and mechanically ventilated. Atelectasis was induced by bronchial blocking: after five minutes of stabilization and pre-oxygenation with FIO2 = 1.0, a silicon cylinder blocker was wedged in the terminal bronchial tree. Afterwards, the animals were randomized between two groups: 1) Tidal volume (VT) = 10 ml/kg and positive end-expiratory pressure (PEEP) = 3 cmH2O (VT10/PEEP3); and 2) VT = 20 ml/kg and PEEP = 0 cmH2O (VT20/zero end-expiratory pressure (ZEEP)). The animals were then ventilated during 180 minutes. Three series of experiments were performed: histological (n = 12); tissue cytokines (n = 12); and micro-computed tomography (microCT; n = 2). An additional six, non-ventilated, healthy animals were used as controls. Atelectasis was successfully induced in the basal region of the lung of 26 out of 29 animals. The microCT of two animals revealed that the volume of the atelectasis was 0.12 and 0.21 cm3. There were more alveolar disruption and neutrophilic infiltration in the peri-atelectasis region than the corresponding contralateral lung (control) in both groups. Edema was higher in the peri-atelectasis region than the corresponding contralateral lung (control) in the VT20/ZEEP than VT10/PEEP3 group. The volume-to-surface ratio was higher in the peri-atelectasis region than the corresponding contralateral lung (control) in both groups. We did not find statistical difference in tissue interleukin-1β and cytokine-induced neutrophil chemoattractant-1 between regions. The present findings suggest that a local non-lobar atelectasis acts as a stress concentrator, generating structural alveolar injury and inflammation in the surrounding lung tissue.

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.

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.

Labour room Continuous Positive Airway Pressure (LR CPAP) in preterm neonates <34 weeks: An Indian experience.

PubMed

Desai, Saumil Ashvinkumar; Tule, Pankaj; Nanavati, Ruchi Nimish

2017-01-01

Early continuous positive airway pressure (CPAP) has proven to be beneficial in reducing ventilator dependence and subsequent chronic lung disease in neonates suffering from Respiratory distress syndrome (RDS). However, the efficacy of initiating labour room (LR) CPAP has not been determined prospectively in resource limited settings like India. Hence the objective of the present study was to study the efficacy of LR CPAP in preterm neonates with RDS in resource limited Indian settings. This was a prospective observational study including preterm neonates (26-34 weeks with RDS) carried out over a period of 6 months (January to June 2016) when the CPAP was initiated in LR. The outcome was compared with a similar population during the corresponding period of the previous year when CPAP was initiated in NICU. The historical controls were retrieved from case records and matched for gestational age and birth weight with the study population. There was 36% absolute risk reduction in the need for surfactant and 56% for mechanical ventilation in the LR CPAP group respectively. LR CPAP reduces the need for mechanical ventilation and surfactant in preterm neonates with RDS in resource limited settings.

Modeling the non-steady state respiratory effects of remifentanil in awake and propofol-sedated healthy volunteers.

PubMed

Olofsen, Erik; Boom, Merel; Nieuwenhuijs, Diederik; Sarton, Elise; Teppema, Luc; Aarts, Leon; Dahan, Albert

2010-06-01

Few studies address the dynamic effect of opioids on respiration. Models with intact feedback control of carbon dioxide on ventilation (non-steady-state models) that correctly incorporate the complex interaction among drug concentration, end-tidal partial pressure of carbon dioxide concentration, and ventilation yield reliable descriptions and predictions of the behavior of opioids. The authors measured the effect of remifentanil on respiration and developed a model of remifentanil-induced respiratory depression. Ten male healthy volunteers received remifentanil infusions with different infusion speeds (target concentrations: 4-9 ng/ml; at infusion rates: 0.17-9 ng x ml x min) while awake and at the background of low-dose propofol. The data were analyzed with a nonlinear model consisting of two additive linear parts, one describing the depressant effect of remifentanil and the other describing the stimulatory effect of carbon dioxide on ventilation. The model adequately described the data including the occurrence of apnea. Most important model parameters were as follows: C50 for respiratory depression 1.6 +/- 0.03 ng/ml, gain of the respiratory controller (G) 0.42 - 0.1 l x min x Torr, and remifentanil blood effect site equilibration half-life (t(1/2)ke0) 0.53 +/- 0.2 min. Propofol caused a 20-50% reduction of C50 and G but had no effect on t(1/2)ke0. Apnea occurred during propofol infusion only. A simulation study revealed an increase in apnea duration at infusion speeds of 2.5-0.5 ng x ml x min followed by a reduction. At an infusion speed of < or = 0.31 ng x ml x min, no apnea was seen. The effect of varying remifentanil infusions with and without a background of low-dose propofol on ventilation and end-tidal partial pressure of carbon dioxide concentration was described successfully using a non-steady-state model of the ventilatory control system. The model allows meaningful simulations and predictions.

Noninvasive versus conventional ventilation to treat hypercapnic encephalopathy in chronic obstructive pulmonary disease.

PubMed

Scala, Raffaele; Nava, Stefano; Conti, Giorgio; Antonelli, Massimo; Naldi, Mario; Archinucci, Ivano; Coniglio, Giovanni; Hill, Nicholas S

2007-12-01

We recently reported a high success rate using noninvasive positive pressure ventilation (NPPV) to treat COPD exacerbations with hypercapnic encephalopathy. This study compared the hospital outcomes of NPPV vs. conventional mechanical ventilation (CMV) in COPD exacerbations with moderate to severe hypercapnic encephalopathy, defined by a Kelly score of 3 or higher. A 3-year prospective matched case-control study in a respiratory semi-intensive care unit (RSICU) and intensive care unit (ICU). From 103 consecutive patients the study included 20 undergoing NPPV and 20 CMV, matched for age, simplified acute physiology score II, and baseline arterial blood gases. ABG significantly improved in both groups after 2 h. The rate of complications was lower in the NPPV group than in the CMV group due to fewer cases of nosocomial pneumonia and sepsis. In-hospital mortality, 1-year mortality, and tracheostomy rates were similar in the two groups. Fewer patients remained on ventilation after 30 days in NPPV group. The NPPV group showed a shorter duration of ventilation. In COPD exacerbations with moderate to severe hypercapnic encephalopathy, the use of NPPV performed by an experienced team compared to CMV leads to similar short and long-term survivals with a reduced nosocomial infection rate and duration of ventilation.

Setting ventilation parameters guided by electrical impedance tomography in an animal trial of acute respiratory distress syndrome

NASA Astrophysics Data System (ADS)

Czaplik, Michael; Biener, Ingeborg; Leonhardt, Steffen; Rossaint, Rolf

2014-03-01

Since mechanical ventilation can cause harm to lung tissue it should be as protective as possible. Whereas numerous options exist to set ventilator parameters, an adequate monitoring is lacking up to date. The Electrical Impedance Tomography (EIT) provides a non-invasive visualization of ventilation which is relatively easy to apply and commercially available. Although there are a number of published measures and parameters derived from EIT, it is not clear how to use EIT to improve clinical outcome of e.g. patients suffering from acute respiratory distress syndrome (ARDS), a severe disease with a high mortality rate. On the one hand, parameters should be easy to obtain, on the other hand clinical algorithms should consider them to optimize ventilator settings. The so called Global inhomogeneity (GI) index bases on the fact that ARDS is characterized by an inhomogeneous injury pattern. By applying positive endexpiratory pressures (PEEP), homogeneity should be attained. In this study, ARDS was induced by a double hit procedure in six pigs. They were randomly assigned to either the EIT or the control group. Whereas in the control group the ARDS network table was used to set the PEEP according to the current inspiratory oxygen fraction, in the EIT group the GI index was calculated during a decremental PEEP trial. PEEP was kept when GI index was lowest. Interestingly, PEEP was significantly higher in the EIT group. Additionally, two of these animals died ahead of the schedule. Obviously, not only homogeneity of ventilation distribution matters but also limitation of over-distension.

[The effectiveness of music therapy in reducing physiological and psychological anxiety in mechanically ventilated patients].

PubMed

Wu, Shiau-Jiun; Chou, Fan-Hao

2008-10-01

Anxiety, a common reaction in patients receiving ventilation therapy, often impacts negatively on patient recovery. Music therapy, a non-invasion intervention, is readily accepted by patients and has been used to relieve patient anxiety with encouraging results. The purpose of this study was to investigate the effectiveness of music therapy on reducing anxiety in patients on mechanical ventilators. An experimental design was used and all cases were collected from a medical center in southern Taiwan. While the experimental group patients took a 30-minute music therapy session, control group patients were asked to rest. Both facility anxiety and anxiety visual scales were used as research tools, with other non-invasive medical instruments employed to measure heartbeat and breathing, blood pressure and blood oxygen saturation in both patient groups. When compared with the control group, patients in the experimental group showed significant improvement in sense of anxiety (Brief Anxiety Scale, BAS, t(29) = -4.80, p < .001; Visual Analogue Anxiety Scales, VAAS, t(29) = -3.38, p = .002), diastolic pressure (t(29) = -2.74, p = .002), mean arterial pressure(t(29) = -2.26, p = .031) and breathing rate (t(29) = -4.84, p < .001). In analyzing data from the two groups, we found that the sense of anxiety (BAS, t(58) = -3.21, p = .002; VAAS, t(58) = -2.90, p = .005) and breathing rate (t(58) = -3.20, p = .002) in the experimental group decreased significantly following music therapy. Study results are hoped to serve as an important reference for clinical nursing staff. Also, it is hoped that the music therapy method may help facilitate achievement of broader humanized nursing goals.

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.

Using Sensor-based Demand Controlled Ventilation to Realize Energy Savings in Laboratories

DTIC Science & Technology

2014-03-27

is warranted. The results show that a DCV system is life-cycle cost effective for many different HVAC system total pressure and square footage ...Name and Description of System Sensors ......................................................... 44 Table 5. BEL Laboratory HVAC Zones, Square Footage ...Intensity ............................................................................. 74 Table 9. Range of USAF Laboratory Square Footage and Occupancy

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.

The effect of changing the sequence of cuff inflation and device fixation with the LMA-Supreme® on device position, ventilatory complications, and airway morbidity: a clinical and fiberscopic study.

PubMed

Bergmann, Ingo; Crozier, Thomas Allen; Roessler, Markus; Schotola, Hanna; Mansur, Ashham; Büttner, Benedikt; Hinz, José Maria; Bauer, Martin

2014-01-04

The conventional sequence when using supraglottic airway devices is insertion, cuff inflation and fixation. Our hypothesis was that a tighter fit of the cuff and tip could be achieved with a consequently lower incidence of air leak, better separation of gastrointestinal and respiratory tracts and less airway morbidity if the device were first affixed and the cuff then inflated. Our clinical review board approved the study (public registry number DRKS00003174). An LMA Supreme® was inserted into 184 patients undergoing lower limb arthroscopy in propofol-remifentanil anaesthesia who were randomly assigned to either the control (inflation then fixation; n = 92) or study group (fixation then inflation; n = 92). The cuff was inflated to 60 cmH2O. The patients' lungs were ventilated in pressure-controlled mode with 5 cmH2O PEEP, Pmax to give 6 ml kg-1 tidal volume, and respiratory rate adjusted to end-tidal CO2 of 4.8 and 5.6 kPa. Correct cuff and tip position were determined by leak detection, capnometry trace, oropharyngeal leak pressure, suprasternal notch test, and lube-tube test. Bowl and cuff position and the presence of glottic narrowing were assessed by fiberscopic examination. Postoperative dysphagia, hoarseness and sore throat were assessed with a questionnaire. Ventilatory impairment was defined as a tidal volume < 6 ml kg-1 with Pmax at oropharyngeal leak pressure, glottic narrowing was defined as an angle between the vocal cords under 16 degrees. The incidence of incorrect device position (18% vs. 21%), failed ventilation (10% vs. 9%), leak pressure (24.8 vs. 25.2 cmH2O, p = 0.63), failed lube-tube test (16.3% vs. 17.6%) and glottic narrowing (19.3% vs. 14.1%, p = 0.35) was similar in both groups (control vs. study, resp.). When glottic narrowing occurred, it was more frequently associated with ventilatory impairment in the control group (77% vs. 39%; p = 0.04). Airway morbidity was more common in the control group (33% vs. 19%; p < 0.05). Altering the sequence of cuff inflation and device fixation does not affect device position, oropharyngeal leak pressures or separation of gastrointestinal and respiratory tracts. It reduces the incidence of glottic narrowing with impaired ventilation and also perioperative airway morbidity.

Natural ventilation for the prevention of airborne contagion.

PubMed

Escombe, A Roderick; Oeser, Clarissa C; Gilman, Robert H; Navincopa, Marcos; Ticona, Eduardo; Pan, William; Martínez, Carlos; Chacaltana, Jesus; Rodríguez, Richard; Moore, David A J; Friedland, Jon S; Evans, Carlton A

2007-02-01

Institutional transmission of airborne infections such as tuberculosis (TB) is an important public health problem, especially in resource-limited settings where protective measures such as negative-pressure isolation rooms are difficult to implement. Natural ventilation may offer a low-cost alternative. Our objective was to investigate the rates, determinants, and effects of natural ventilation in health care settings. The study was carried out in eight hospitals in Lima, Peru; five were hospitals of "old-fashioned" design built pre-1950, and three of "modern" design, built 1970-1990. In these hospitals 70 naturally ventilated clinical rooms where infectious patients are likely to be encountered were studied. These included respiratory isolation rooms, TB wards, respiratory wards, general medical wards, outpatient consulting rooms, waiting rooms, and emergency departments. These rooms were compared with 12 mechanically ventilated negative-pressure respiratory isolation rooms built post-2000. Ventilation was measured using a carbon dioxide tracer gas technique in 368 experiments. Architectural and environmental variables were measured. For each experiment, infection risk was estimated for TB exposure using the Wells-Riley model of airborne infection. We found that opening windows and doors provided median ventilation of 28 air changes/hour (ACH), more than double that of mechanically ventilated negative-pressure rooms ventilated at the 12 ACH recommended for high-risk areas, and 18 times that with windows and doors closed (p < 0.001). Facilities built more than 50 years ago, characterised by large windows and high ceilings, had greater ventilation than modern naturally ventilated rooms (40 versus 17 ACH; p < 0.001). Even within the lowest quartile of wind speeds, natural ventilation exceeded mechanical (p < 0.001). The Wells-Riley airborne infection model predicted that in mechanically ventilated rooms 39% of susceptible individuals would become infected following 24 h of exposure to untreated TB patients of infectiousness characterised in a well-documented outbreak. This infection rate compared with 33% in modern and 11% in pre-1950 naturally ventilated facilities with windows and doors open. Opening windows and doors maximises natural ventilation so that the risk of airborne contagion is much lower than with costly, maintenance-requiring mechanical ventilation systems. Old-fashioned clinical areas with high ceilings and large windows provide greatest protection. Natural ventilation costs little and is maintenance free, and is particularly suited to limited-resource settings and tropical climates, where the burden of TB and institutional TB transmission is highest. In settings where respiratory isolation is difficult and climate permits, windows and doors should be opened to reduce the risk of airborne contagion.

Standardized Application of Laxatives and Physical Measures in Neurosurgical Intensive Care Patients Improves Defecation Pattern but Is Not Associated with Lower Intracranial Pressure

PubMed Central

Kieninger, Martin; Sinner, Barbara; Graf, Bernhard; Grassold, Astrid; Bele, Sylvia; Seemann, Milena; Künzig, Holger; Zech, Nina

2014-01-01

Background. Inadequate bowel movements might be associated with an increase in intracranial pressure in neurosurgical patients. In this study we investigated the influence of a structured application of laxatives and physical measures following a strict standard operating procedure (SOP) on bowel movement, intracranial pressure (ICP), and length of hospital stay in patients with a serious acute cerebral disorder. Methods. After the implementation of the SOP patients suffering from a neurosurgical disorder received pharmacological and nonpharmacological measures to improve bowel movements in a standardized manner within the first 5 days after admission to the intensive care unit (ICU) starting on day of admission. We compared mean ICP levels, length of ICU stay, and mechanical ventilation to a historical control group. Results. Patients of the intervention group showed an adequate defecation pattern significantly more often than the patients of the control group. However, this was not associated with lower ICP values, fewer days of mechanical ventilation, or earlier discharge from ICU. Conclusions. The implementation of a SOP for bowel movement increases the frequency of adequate bowel movements in neurosurgical critical care patients. However, this seems not to be associated with reduced ICP values. PMID:25628896

Simulated Altitude Investigation of Stewart-Warner Model 906-B Combustion Heater

NASA Technical Reports Server (NTRS)

Ebersbach, Frederick R.; Cervenka, Adolph J.

1947-01-01

An investigation has been conducted to determine thermal and pressure-drop performance and the operational characteristics of a Stewart-Warner model 906-B combustion heater. The performance tests covered a range of ventilating-air flows from 500 to 3185 pounds per hour, combustion-air pressure drops from 5 to 35 inches of water, and pressure altitudes from sea level to 41,000 feet. The operational characteristics investigated were the combustion-air flows for sustained combustion and for consistent ignition covering fuel-air ratios ranging from 0.033 to 0.10 and pressure altitudes from sea level to 45,000 feet. Rated heat output of 50,000 Btu per hour was obtained at pressure altitudes up to 27,000 feet for ventilating-air flows greater than 800 pounds per hour; rated output was not obtained at ventilating-air flow below 800 pounds per hour at any altitude. The maximum heater efficiency was found to be 60.7 percent at a fuel-air ratio of 0.050, a sea-level pressure altitude, a ventilating-air temperature of 0 F, combustion-air temperature of 14 F, a ventilating-air flow of 690 pounds per hour, and a combustion-air flow of 72.7 pounds per hour. The minimum combustion-air flow for sustained combustion at a pressure altitude of 25,000 feet was about 9 pounds per hour for fuel-air ratios between 0.037 and 0.099 and at a pressure altitude of 45,000 feet increased to 18 pounds per hour at a fuel-air ratio of 0.099 and 55 pounds per hour at a fuel-air ratio of 0.036. Combustion could be sustained at combustion-air flows above values of practical interest. The maximum flow was limited, however, by excessively high exhaust-gas temperature or high pressure drop. Both maximum and minimum combustion-air flows for consistent ignition decrease with increasing pressure altitude and the two curves intersect at a pressure altitude of approximately 25,000 feet and a combustion-air flow of approximately 28 pounds per hour.

Influences of meteorological parameters on indoor radon concentrations (222Rn) excluding the effects of forced ventilation and radon exhalation from soil and building materials.

PubMed

Schubert, Michael; Musolff, Andreas; Weiss, Holger

2018-06-13

Elevated indoor radon concentrations ( 222 Rn) in dwellings pose generally a potential health risk to the inhabitants. During the last decades a considerable number of studies discussed both the different sources of indoor radon and the drivers for diurnal and multi day variations of its concentration. While the potential sources are undisputed, controversial opinions exist regarding their individual relevance and regarding the driving influences that control varying radon indoor concentrations. These drivers include (i) cyclic forced ventilation of dwellings, (ii) the temporal variance of the radon exhalation from soil and building materials due to e.g. a varying moisture content and (iii) diurnal and multi day temperature and pressure patterns. The presented study discusses the influences of last-mentioned temporal meteorological parameters by effectively excluding the influences of forced ventilation and undefined radon exhalation. The results reveal the continuous variation of the indoor/outdoor pressure gradient as key driver for a constant "breathing" of any interior space, which affects the indoor radon concentration with both diurnal and multi day patterns. The diurnally recurring variation of the pressure gradient is predominantly triggered by the day/night cycle of the indoor temperature that is associated with an expansion/contraction of the indoor air volume. Multi day patterns, on the other hand, are mainly due to periods of negative air pressure indoors that is triggered by periods of elevated wind speeds as a result of Bernoulli's principle. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sleep in heart failure.

PubMed

Naughton, Matthew T; Lorenzi-Filho, Geraldo

2009-01-01

Sleep plays a large role in patients with heart failure. In normal subjects, sleep is usually in a supine position with reduced sympathetic drive, elevated vagal tone and as such a relatively lower cardiac output and minute ventilation, allowing for recuperation. Patients with heart failure may not experience the same degree of autonomic activity change and the supine position may place a large strain on the pulmonary system. More than half of all heart failure patients have one of two types of sleep apnea: either obstructive or central sleep apnea. Some patients have both types. Obstructive sleep apnea is likely to be a cause of heart failure due to large negative intrathoracic pressures, apnea related hypoxemia and hypercapnia, terminated by an arousal and surge in systemic blood pressure associated with endothelial damage and resultant premature atherosclerosis. Reversal of obstructive sleep apnea improves blood pressure, systolic contraction and autonomic dysfunction however mortality studies are lacking. Central sleep apnea with Cheyne Stokes pattern of respiration (CSA-CSR) occurs as a result of increased central controller (brainstem driving ventilation) and plant (ventilation driving CO2) gain in the setting of a delayed feed back (i.e., low cardiac output). It is thought this type of apnea is a result of moderately to severely impaired cardiac function and is possibly indicative of high mortality. Treatment of CSA-CSR is best undertaken by treating the underlying cardiac condition which may include with medications, pacemakers, transplantation or continuous positive airway pressure (CPAP). In such patients CPAP exerts unique effects to assist cardiac function and reduce pulmonary edema. Whether CPAP improves survival in this heart failure population remains to be determined.

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.

[Effectiveness of nasal positive pressure ventilation in the management of acute refractory left ventricular insufficiency].

PubMed

Chesi, G; Pinelli, G; Galimberti, D; Navazio, A; Montanari, P

1994-04-01

Ehen refractory to optimal medical treatment cardiogenic pulmonary edema requires mechanical ventilation as a last therapeutic resource. In recent years an increasing number of authors reported their experience in the management of acute or subacute respiratory failure with non-invasive mechanical ventilation by nasal mask. Encouraged by the first promising results reported in literature we experimented this new therapeutic tool in a first group of seven elderly patients (mean age: 76.57--range: 65-89); they all had been admitted for severe cardiogenic pulmonary edema unresponsive to maximal doses of the conventional drugs available for treating acute decompensated heart failure. The enrolled patients were treated with intermittent ventilation administered by nasal mask at selected values of inspiratory positive airway pressure (IPAP) that were comprised between 10 and 20 cm H2O. At the same time an expiratory positive airway pressure (EPAP) at values comprised between 3 and 8 cm H2O was applied. Ventilation was continued for variable periods of 3-24 hours until acceptable values of PaO2 and PaCO2 were obtained. The ventilation modality was spontaneous, spontaneous-time or timed depending on the patients' level of consciousness at starting time. A good short-term outcome was achieved in all the patients regardless of the ventilation modality applied. The main blood gas alteration was severe hypercapnia with acidosis in three patients, while the other four presented critical hypoxemia unresponsive to simple oxygen supply even if delivered by high-flow Venturi mask. Four of our seven patients were discharged from hospital in satisfactory haemodynamic conditions; the remaining three died during hospitalization from refractory heart failure. In this our preliminary experience the therapeutic approach with nasal positive pressure ventilation (NPPV) and EPAP proved to be very effective to improve the signs and symptoms of acute refractory cardiogenic pulmonary edema as it avoided the need of invasive mechanical ventilation. It was well tolerated by all our patients; besides it was not difficult to use or time-consuming for physician and nurses. On the other hand it didn't modify our patients' medium or long-time prognosis which was strictly related to their preexisting left ventricular pump derangement.

Intra-aortic balloon pump combined with mechanical ventilation for treating patients aged > 60 years in cardiogenic shock: Retrospective analysis

PubMed Central

Liu, Hongwei; Wu, Xueping; Zhao, Xiaoning; Zhu, Ping

2016-01-01

Objective To examine if mechanical ventilation with positive end-expiratory pressure (PEEP) combined with intra-aortic balloon pump (IABP) provided a better outcome than IABP alone for the treatment of cardiogenic shock after acute myocardial infarction in patients aged > 60 years. Methods This was a retrospective analysis of data from patients in cardiogenic shock, refractory to pharmacological therapy and treated at a geriatric coronary care unit. Results Sixty-two patients were eligible for study inclusion: 33 received IABP alone; 29 received IABP combined with mechanical ventilation. Patients in the IABP + mechanical ventilation group had lower mean arterial blood pressure (BP), systolic BP and partial pressure of oxygen compared with the IABP group, indicating worse cardiac and pulmonary function. In addition, higher rates of pulmonary infection and renal insufficiency were observed in the IABP + mechanical ventilation group than in the IABP group. A statistically significant improvement of left ventricular function before and after treatment was observed in the IABP + mechanical ventilation group, but not in the IABP group. Pulmonary infection and renal insufficiency were risk factors for all-cause in-hospital mortality; successful revascularization was a negative risk factor. There was no between-group difference in survival. Conclusion Mechanical ventilation with an appropriate level of PEEP appears to enhance the beneficial effects of IABP on left ventricular function for patients in cardiogenic shock. PMID:27020597

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.

Open-air sprays for capturing and controlling airborne float coal dust on longwall faces

PubMed Central

Beck, T.W.; Seaman, C.E.; Shahan, M.R.; Mischler, S.E.

2018-01-01

Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening. PMID:29348700

Open-air sprays for capturing and controlling airborne float coal dust on longwall faces.

PubMed

Beck, T W; Seaman, C E; Shahan, M R; Mischler, S E

2018-01-01

Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening.

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.

Mask Ventilation during Induction of General Anesthesia: Influences of Obstructive Sleep Apnea.

PubMed

Sato, Shin; Hasegawa, Makoto; Okuyama, Megumi; Okazaki, Junko; Kitamura, Yuji; Sato, Yumi; Ishikawa, Teruhiko; Sato, Yasunori; Isono, Shiroh

2017-01-01

Depending on upper airway patency during anesthesia induction, tidal volume achieved by mask ventilation may vary. In 80 adult patients undergoing general anesthesia, the authors tested a hypothesis that tidal volume during mask ventilation is smaller in patients with sleep-disordered breathing priorly defined as apnea hypopnea index greater than 5 per hour. One-hand mask ventilation with a constant ventilator setting (pressure-controlled ventilation) was started 20 s after injection of rocuronium and maintained for 1 min during anesthesia induction. Mask ventilation efficiency was assessed by the breath number needed to initially exceed 5 ml/kg ideal body weight of expiratory tidal volume (primary outcome) and tidal volumes (secondary outcomes) during initial 15 breaths (UMIN000012494). Tidal volume progressively increased by more than 70% in 1 min and did not differ between sleep-disordered breathing (n = 42) and non-sleep-disordered breathing (n = 38) patients. In post hoc subgroup analyses, the primary outcome breath number (mean [95% CI], 5.7 [4.1 to 7.3] vs. 1.7 [0.2 to 3.2] breath; P = 0.001) and mean tidal volume (6.5 [4.6 to 8.3] vs. 9.6 [7.7 to 11.4] ml/kg ideal body weight; P = 0.032) were significantly smaller in 20 sleep-disordered breathing patients with higher apnea hypopnea index (median [25th to 75th percentile]: 21.7 [17.6 to 31] per hour) than in 20 non-sleep disordered breathing subjects with lower apnea hypopnea index (1.0 [0.3 to 1.5] per hour). Obesity and occurrence of expiratory flow limitation during one-hand mask ventilation independently explained the reduction of efficiency of mask ventilation, while the use of two hands effectively normalized inefficient mask ventilation during one-hand mask ventilation. One-hand mask ventilation is difficult in patients with obesity and severe sleep-disordered breathing particularly when expiratory flow limitation occurs during mask ventilation.

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.

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.

Positive pressure ventilation in the management of acute and chronic cardiac failure: a systematic review and meta-analysis.

PubMed

Nadar, Sunil; Prasad, Neeraj; Taylor, Rod S; Lip, Gregory Y H

2005-03-18

Chronic heart failure (CHF) is a common condition and is associated with excess morbidity and mortality, in spite of the many advances in its treatment. Chronic stable heart failure is also associated with an increased incidence of sleep-related breathing disorders, such as central sleep apnoea (CSA) and Cheyne Stokes respiration (CSR). Continuous positive airways pressure (CPAP) has been shown to alleviate the symptoms of CHF, improve left ventricular function and oxygenation. To a certain extent, CPAP also abolishes sleep-related breathing disorders in patients with chronic heart failure. In patients with acute pulmonary oedema, the use of positive pressure ventilation improves cardiac haemodynamic indices, as well as symptoms and oxygenation, and is associated with a lower need for intubation. However, some studies have cast doubts about its safety and suggest a higher rate of myocardial infarction associated with its use. In our opinion, non-invasive positive pressure ventilation and CPAP offers an adjunctive mode of therapy in patients with acute pulmonary oedema and chronic heart failure, who may not be suitable for intubation and in those not responsive to conventional therapies. Non-invasive ventilation also helps to improve oxygenation in those patients with exhaustion and respiratory acidosis. Many trials are still ongoing and the results of these studies would throw more light on the present role of non-invasive ventilation in the management of CHF.

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.

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

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

A multicentre randomised controlled trial of the use of continuous positive airway pressure and non-invasive positive pressure ventilation in the early treatment of patients presenting to the emergency department with severe acute cardiogenic pulmonary oedema: the 3CPO trial.

PubMed

Gray, A J; Goodacre, S; Newby, D E; Masson, M A; Sampson, F; Dixon, S; Crane, S; Elliott, M; Nicholl, J

2009-07-01

To determine whether non-invasive ventilation reduces mortality and whether there are important differences in outcome by treatment modality. Multicentre open prospective randomised controlled trial. Patients presenting with severe acute cardiogenic pulmonary oedema in 26 emergency departments in the UK. Inclusion criteria were age > 16 years, clinical diagnosis of acute cardiogenic pulmonary oedema, pulmonary oedema on chest radiograph, respiratory rate > 20 breaths per minute, and arterial hydrogen ion concentration > 45 nmol/l (pH < 7.35). Patients were randomised to standard oxygen therapy, continuous positive airway pressure (CPAP) (5-15 cmH2O) or non-invasive positive pressure ventilation (NIPPV) (inspiratory pressure 8-20 cmH2O, expiratory pressure 4-10 cmH2O) on a 1:1:1 basis for a minimum of 2 hours. The primary end point for the comparison between NIPPV or CPAP and standard therapy was 7-day mortality. The composite primary end point for the comparison of NIPPV and CPAP was 7-day mortality and tracheal intubation rate. Secondary end points were breathlessness, physiological variables, intubation rate, length of hospital stay and critical care admission rate. Economic evaluation took the form of a cost-utility analysis, taken from an NHS (and personal social services) perspective. In total, 1069 patients [mean age 78 (SD 10) years; 43% male] were recruited to standard therapy (n = 367), CPAP [n = 346; mean 10 (SD 4) cmH2O] or NIPPV [n = 356; mean 14 (SD 5)/7 (SD 2) cmH2O]. There was no difference in 7-day mortality for standard oxygen therapy (9.8%) and non-invasive ventilation (9.5%; p = 0.87). The combined end point of 7-day death and intubation rate was similar, irrespective of non-invasive ventilation modality (CPAP 11.7% versus NIPPV 11.1%; p = 0.81). Compared with standard therapy, non-invasive ventilation was associated with greater reductions (treatment difference, 95% confidence intervals) in breathlessness (visual analogue scale score 0.7, 0.2-1.3; p = 0.008) and heart rate (4/min, 1-6; p = 0.004) and improvement in acidosis (pH 0.03, 0.02-0.04; p < 0.001) and hypercapnia (0.7 kPa, 0.4-0.9; p < 0.001) at 1 hour. There were no treatment-related adverse events or differences in other secondary outcomes such as myocardial infarction rate, length of hospital stay, critical care admission rate and requirement for endotracheal intubation. Economic evaluation showed that mean costs and QALYs up to 6 months were 3023 pounds and 0.202 for standard therapy, 3224 pounds and 0.213 for CPAP, and 3208 pounds and 0.210 for NIPPV. Modelling of lifetime costs and QALYs produced values of 15,764 pounds and 1.597 for standard therapy, 17,525 pounds and 1.841 for CPAP, and 17,021 pounds and 1.707 for NIPPV. These results suggest that both CPAP and NIPPV accrue more QALYs but at higher cost than standard therapy. However, these estimates are subject to substantial uncertainty. Non-invasive ventilatory support delivered by either CPAP or NIPPV safely provides earlier improvement and resolution of breathlessness, respiratory distress and metabolic abnormality. However, this does not translate into improved short- or longer-term survival. We recommend that CPAP or NIPPV should be considered as adjunctive therapy in patients with severe acute cardiogenic pulmonary oedema in the presence of severe respiratory distress or when there is a failure to improve with pharmacological therapy. Current Controlled Trials ISRCTN07448447.

Effects of positive end-expiratory pressure on intracranial pressure in mechanically ventilated dogs under hyperbaric oxygenation.

PubMed

Sun, Qing; Wu, Di; Yu, Tao; Yang, Ying; Wei, Li; Lv, Fuxiang; Gao, Guangkai

2014-01-01

Mechanical ventilation with positive end-expiratory pressure (PEEP) has been advocated as an essential life support for critical patients. However, its side effect, which is demonstrated by an elevation of intracranial pressure (ICP) under normobaric (NBO2) conditions, is potentially detrimental to patients. Hyperbaric oxygen (HBO2) therapy, on the other hand, is frequently applied for the same group of patients, and its efficacy is shown by maintaining a higher PaO2 and a reduced ICP. Our study investigated the effect of HBO2 and NBO2 on ICP with or without PEEP ventilation on healthy dogs by comparing cerebrospinal fluid pressure (CSFP) and concluded that the elevation of PEEP resulted in a significant increase of ICP (CSFP) under both conditions (p < 0.05). HBO2 leads to a lower ICP increase compared to the NBO2 group. Under the same level of PEEP, the joint use of PEEP and HBO2 is safe and highly practical in clinical medicine.

"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.

Cost-Effectiveness Analysis of Nasal Continuous Positive Airway Pressure Versus Nasal High Flow Therapy as Primary Support for Infants Born Preterm.

PubMed

Huang, Li; Roberts, Calum T; Manley, Brett J; Owen, Louise S; Davis, Peter G; Dalziel, Kim M

2018-05-01

To compare the cost-effectiveness of 2 common "noninvasive" modes of respiratory support for infants born preterm. An economic evaluation was conducted as a component of a multicenter, randomized control trial from 2013 to 2015 enrolling infants born preterm at ≥28 weeks of gestation with respiratory distress, <24 hours old, who had not previously received endotracheal intubation and mechanical ventilation or surfactant. The economic evaluation was conducted from a healthcare sector perspective and the time horizon was from birth until death or first discharge. The cost-effectiveness of continuous positive airway pressure (CPAP) vs high-flow with "rescue" CPAP backup and high-flow without rescue CPAP backup (as sole primary support) were analyzed by using the hospital cost of inpatient stay in a tertiary center and the rates of endotracheal intubation and mechanical ventilation during admission. Hospital inpatient cost records for 435 infants enrolled in all Australian centers were obtained. With "rescue" CPAP backup, an incremental cost-effectiveness ratio was estimated of A$179 000 (US$123 000) per ventilation avoided if CPAP was used compared with high flow. Without rescue CPAP backup, cost per ventilation avoided was A$7000 (US$4800) if CPAP was used compared with high flow. As sole primary support, CPAP is highly likely to be cost-effective compared with high flow. Neonatal units choosing to use only one device should apply CPAP as primary respiratory support. Compared with high-flow with rescue CPAP backup, CPAP is unlikely to be cost-effective if willingness to pay per ventilation avoided is less than A$179 000 (US$123 000). Copyright © 2018 Elsevier Inc. All rights reserved.

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.

The Phase of Illness Paradigm: A Checklist Centric Model to Improve Patient Care in the Burn Intensive Care Unit

DTIC Science & Technology

2016-04-01

oxygenation and ventilation Goal Adequate oxygenation and/or ventilation Goal Skin grafting Objective Surgical operation (implicit goal = achieve...Abdominal Pressures, [TTE/IVC measurement] Assure effective Ventilation & Sedation (Standard ICU) EtCO2, A-Line, ±CVP 4E Compatible Decrease...commands) Participatory (expresses self)  minimize oxygen demand  maximize perfusion  protect grafts  patient ventilator

Patient-ventilator asynchrony affects pulse pressure variation prediction of fluid responsiveness.

PubMed

Messina, Antonio; Colombo, Davide; Cammarota, Gianmaria; De Lucia, Marta; Cecconi, Maurizio; Antonelli, Massimo; Corte, Francesco Della; Navalesi, Paolo

2015-10-01

During partial ventilatory support, pulse pressure variation (PPV) fails to adequately predict fluid responsiveness. This prospective study aims to investigate whether patient-ventilator asynchrony affects PPV prediction of fluid responsiveness during pressure support ventilation (PSV). This is an observational physiological study evaluating the response to a 500-mL fluid challenge in 54 patients receiving PSV, 27 without (Synch) and 27 with asynchronies (Asynch), as assessed by visual inspection of ventilator waveforms by 2 skilled blinded physicians. The area under the curve was 0.71 (confidence interval, 0.57-0.83) for the overall population, 0.86 (confidence interval, 0.68-0.96) in the Synch group, and 0.53 (confidence interval, 0.33-0.73) in the Asynch group (P = .018). Sensitivity and specificity of PPV were 78% and 89% in the Synch group and 36% and 46% in the Asynch group. Logistic regression showed that the PPV prediction was influenced by patient-ventilator asynchrony (odds ratio, 8.8 [2.0-38.0]; P < .003). Of the 27 patients without asynchronies, 12 had a tidal volume greater than or equal to 8 mL/kg; in this subgroup, the rate of correct classification was 100%. Patient-ventilator asynchrony affects PPV performance during partial ventilatory support influencing its efficacy in predicting fluid responsiveness. Copyright © 2015 Elsevier Inc. All rights reserved.

Monitoring of intratidal lung mechanics: a Graphical User Interface for a model-based decision support system for PEEP-titration in mechanical ventilation.

PubMed

Buehler, S; Lozano-Zahonero, S; Schumann, S; Guttmann, J

2014-12-01

In mechanical ventilation, a careful setting of the ventilation parameters in accordance with the current individual state of the lung is crucial to minimize ventilator induced lung injury. Positive end-expiratory pressure (PEEP) has to be set to prevent collapse of the alveoli, however at the same time overdistension should be avoided. Classic approaches of analyzing static respiratory system mechanics fail in particular if lung injury already prevails. A new approach of analyzing dynamic respiratory system mechanics to set PEEP uses the intratidal, volume-dependent compliance which is believed to stay relatively constant during one breath only if neither atelectasis nor overdistension occurs. To test the success of this dynamic approach systematically at bedside or in an animal study, automation of the computing steps is necessary. A decision support system for optimizing PEEP in form of a Graphical User Interface (GUI) was targeted. Respiratory system mechanics were analyzed using the gliding SLICE method. The resulting shapes of the intratidal compliance-volume curve were classified into one of six categories, each associated with a PEEP-suggestion. The GUI should include a graphical representation of the results as well as a quality check to judge the reliability of the suggestion. The implementation of a user-friendly GUI was successfully realized. The agreement between modelled and measured pressure data [expressed as root-mean-square (RMS)] tested during the implementation phase with real respiratory data from two patient studies was below 0.2 mbar for data taken in volume controlled mode and below 0.4 mbar for data taken in pressure controlled mode except for two cases with RMS < 0.6 mbar. Visual inspections showed, that good and medium quality data could be reliably identified. The new GUI allows visualization of intratidal compliance-volume curves on a breath-by-breath basis. The automatic categorisation of curve shape into one of six shape-categories provides the rational decision-making model for PEEP-titration.

Aerodynamic Characteristics of the Ventilated Design for Flapping Wing Micro Air Vehicle

PubMed Central

Zhang, G. Q.; Yu, S. C. M.

2014-01-01

Inspired by superior flight performance of natural flight masters like birds and insects and based on the ventilating flaps that can be opened and closed by the changing air pressure around the wing, a new flapping wing type has been proposed. It is known that the net lift force generated by a solid wing in a flapping cycle is nearly zero. However, for the case of the ventilated wing, results for the net lift force are positive which is due to the effect created by the “ventilation” in reducing negative lift force during the upstroke. The presence of moving flaps can serve as the variable in which, through careful control of the areas, a correlation with the decrease in negative lift can be generated. The corresponding aerodynamic characteristics have been investigated numerically by using different flapping frequencies and forward flight speeds. PMID:24683339

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.

Cardiopulmonary and arterial baroreceptor unloading during passive hyperthermia does not contribute to hyperthermia-induced hyperventilation.

PubMed

Lucas, Rebekah A I; Pearson, James; Schlader, Zachary J; Crandall, Craig G

2015-11-01

What is the central question of this study? Does baroreceptor unloading during passive hyperthermia contribute to increases in ventilation and decreases in end-tidal carbon dioxide during that exposure? What is the main finding and its importance? Hyperthermic hyperventilation is not mitigated by expanding central blood volume and reloading the cardiopulmonary baroreceptors via rapid saline infusion or by reloading the arterial baroreceptors via phenylephrine administration. The absence of a reduction in ventilation upon reloading the baroreceptors to pre-hyperthermic levels indicates that cardiopulmonary and arterial baroreceptor unloading with hyperthermia is unlikely to contribute to hyperthermic hyperventilation in humans. This study tested the hypothesis that baroreceptor unloading during passive hyperthermia contributes to increases in ventilation and decreases in end-tidal partial pressure of carbon dioxide (P ET ,CO2) during that exposure. Two protocols were performed, in which healthy subjects underwent passive hyperthermia (increasing intestinal temperature by ∼1.8°C) to cause a sustained increase in ventilation and reduction in P ET ,CO2. Upon attaining hyperthermic hyperventilation, in protocol 1 (n = 10; three females) a bolus (19 ± 2 ml kg(-1) ) of warm (∼38°C) isotonic saline was rapidly (5-10 min) infused intravenously to restore reductions in central venous pressure, whereas in protocol 2 (n = 11; five females) phenylephrine was infused intravenously (60-120 μg min(-1) ) to return mean arterial pressure to normothermic levels. In protocol 1, hyperthermia increased ventilation (by 2.2 ± 1.7 l min(-1) , P < 0.01), while reducing P ET ,CO2 (by 4 ± 3 mmHg, P = 0.04) and central venous pressure (by 5 ± 1 mmHg, P <0.01). Saline infusion increased central venous pressure by 5 ± 1 mmHg (P < 0.01), restoring it to normothermic values, but did not change ventilation or P ET ,CO2 (P > 0.05). In protocol 2, hyperthermia increased ventilation (by 5.0 ± 2.7 l min(-1) , P <0.01) and reduced P ET ,CO2 (by 5 ± 2 mmHg, P < 0.01) and mean arterial pressure (by 9 ± 7 mmHg, P <0.01). Phenylephrine infusion increased mean arterial pressure by 12 ± 3 mmHg (P < 0.01), restoring it to normothermic values, but did not change ventilation or P ET ,CO2 (P > 0.05). The absence of a reduction in ventilation upon reloading the cardiopulmonary and arterial baroreceptors to pre-hyperthermic levels indicates that baroreceptor unloading with hyperthermia is unlikely to contribute to hyperthermic hyperventilation in humans. © 2015 The Authors. Experimental Physiology © 2015 The Physiological Society.

Comparative evaluation of hemodynamic and respiratory parameters during mechanical ventilation with two tidal volumes calculated by demi-span based height and measured height in normal lungs

PubMed Central

Seresht, L. Mousavi; Golparvar, Mohammad; Yaraghi, Ahmad

2014-01-01

Background: Appropriate determination of tidal volume (VT) is important for preventing ventilation induced lung injury. We compared hemodynamic and respiratory parameters in two conditions of receiving VTs calculated by using body weight (BW), which was estimated by measured height (HBW) or demi-span based body weight (DBW). Materials and Methods: This controlled-trial was conducted in St. Alzahra Hospital in 2009 on American Society of Anesthesiologists (ASA) I and II, 18-65-years-old patients. Standing height and weight were measured and then height was calculated using demi-span method. BW and VT were calculated with acute respiratory distress syndrome-net formula. Patients were randomized and then crossed to receive ventilation with both calculated VTs for 20 min. Hemodynamic and respiratory parameters were analyzed with SPSS version 20.0 using univariate and multivariate analyses. Results: Forty nine patients were studied. Demi-span based body weight and thus VT (DTV) were lower than Height based body weight and VT (HTV) (P = 0.028), in male patients (P = 0.005). Difference was observed in peak airway pressure (PAP) and airway resistance (AR) changes with higher PAP and AR at 20 min after receiving HTV compared with DTV. Conclusions: Estimated VT based on measured height is higher than that based on demi-span and this difference exists only in females, and this higher VT results higher airway pressures during mechanical ventilation. PMID:24627845

Comparative evaluation of hemodynamic and respiratory parameters during mechanical ventilation with two tidal volumes calculated by demi-span based height and measured height in normal lungs.

PubMed

Seresht, L Mousavi; Golparvar, Mohammad; Yaraghi, Ahmad

2014-01-01

Appropriate determination of tidal volume (VT) is important for preventing ventilation induced lung injury. We compared hemodynamic and respiratory parameters in two conditions of receiving VTs calculated by using body weight (BW), which was estimated by measured height (HBW) or demi-span based body weight (DBW). This controlled-trial was conducted in St. Alzahra Hospital in 2009 on American Society of Anesthesiologists (ASA) I and II, 18-65-years-old patients. Standing height and weight were measured and then height was calculated using demi-span method. BW and VT were calculated with acute respiratory distress syndrome-net formula. Patients were randomized and then crossed to receive ventilation with both calculated VTs for 20 min. Hemodynamic and respiratory parameters were analyzed with SPSS version 20.0 using univariate and multivariate analyses. Forty nine patients were studied. Demi-span based body weight and thus VT (DTV) were lower than Height based body weight and VT (HTV) (P = 0.028), in male patients (P = 0.005). Difference was observed in peak airway pressure (PAP) and airway resistance (AR) changes with higher PAP and AR at 20 min after receiving HTV compared with DTV. Estimated VT based on measured height is higher than that based on demi-span and this difference exists only in females, and this higher VT results higher airway pressures during mechanical ventilation.

30 CFR 75.333 - Ventilation controls.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Ventilation controls. 75.333 Section 75.333... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.333 Ventilation controls. (a) For... ventilation control devices constructed after November 15, 1992, shall be built and maintained— (1) Between...

30 CFR 75.333 - Ventilation controls.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Ventilation controls. 75.333 Section 75.333... MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation § 75.333 Ventilation controls. (a) For... ventilation control devices constructed after November 15, 1992, shall be built and maintained— (1) Between...

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

Delayed extubation to nasal continuous positive airway pressure in the immature baboon model of bronchopulmonary dysplasia: lung clinical and pathological findings.

PubMed

Thomson, Merran A; Yoder, Bradley A; Winter, Vicki T; Giavedoni, Luis; Chang, Ling Yi; Coalson, Jacqueline J

2006-11-01

Using the 125-day baboon model of bronchopulmonary dysplasia treated with prenatal steroid and exogenous surfactant, we hypothesized that a delay of extubation from low tidal volume positive pressure ventilation to nasal continuous positive airway pressure at 5 days (delayed nasal continuous positive airway pressure group) would not induce more lung injury when compared with baboons aggressively weaned to nasal continuous positive airway pressure at 24 hours (early nasal continuous positive airway pressure group), because both received positive pressure ventilation. After delivery by cesarean section at 125 days (term: 185 days), infants received 2 doses of Curosurf (Chiesi Farmaceutica S.p.A., Parma, Italy) and daily caffeine citrate. The delay in extubation to 5 days resulted in baboons in the delayed nasal continuous positive airway pressure group having a lower arterial to alveolar oxygen ratio, high PaCO2, and worse respiratory function. The animals in the delayed nasal continuous positive airway pressure group exhibited a poor respiratory drive that contributed to more reintubations and time on mechanical ventilation. A few animals in both groups developed necrotizing enterocolitis and/or sepsis, but infectious pneumonias were not documented. Cellular bronchiolitis and peribronchiolar alveolar wall thickening were more frequently seen in the delayed nasal continuous positive airway pressure group. Bronchoalveolar lavage levels of interleukin-6, interleukin-8, monocyte chemotactic protein-1, macrophage inflammatory protein-1 alpha, and growth-regulated oncogene-alpha were significantly increased in the delayed nasal continuous positive airway pressure group. Standard and digital morphometric analyses showed no significant differences in internal surface area and nodal measurements between the groups. Platelet endothelial cell adhesion molecule vascular staining was not significantly different between the 2 nasal continuous positive airway pressure groups. Volutrauma and/or low-grade colonization of airways secondary to increased reintubations and ventilation times are speculated to play causative roles in the delayed nasal continuous positive airway pressure group findings.

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...

[Successful airway management using i-gel in 7 patients undergoing awake craniotomy].

PubMed

Matsunami, Katsuaki; Sanuki, Michiyoshi; Yasuuji, Masakazu; Nakanuno, Ryuichi; Kato, Takahiro; Kawamoto, Masashi

2014-07-01

In order to secure airway during awake craniotomy, we used i-gel to perform positive-pressure ventilation in 7 patients for their anesthetic management. During removal of a tumor around the motor speech center, anesthetic management including asleep-awake-asleep technique was applied for speech testing. The technique, insertion and re-insertion of i-gel, was needed and it was easy in all the patients. During positive-pressure ventilation, peak pressure, tidal volume both for inspiration and expiration, and endtidal-CO2 were not markedly altered. Leakage around i-gel, and its differences between inspiration and expiration were negligible, while the tidal volume was adequate. We conclude that i-gel is useful for anesthetic management for awake craniotomy procedure for both securing airway and ventilation.

Integrated analysis of numerical weather prediction and computational fluid dynamics for estimating cross-ventilation effects on inhaled air quality inside a factory

NASA Astrophysics Data System (ADS)

Murga, Alicia; Sano, Yusuke; Kawamoto, Yoichi; Ito, Kazuhide

2017-10-01

Mechanical and passive ventilation strategies directly impact indoor air quality. Passive ventilation has recently become widespread owing to its ability to reduce energy demand in buildings, such as the case of natural or cross ventilation. To understand the effect of natural ventilation on indoor environmental quality, outdoor-indoor flow paths need to be analyzed as functions of urban atmospheric conditions, topology of the built environment, and indoor conditions. Wind-driven natural ventilation (e.g., cross ventilation) can be calculated through the wind pressure coefficient distributions of outdoor wall surfaces and openings of a building, allowing the study of indoor air parameters and airborne contaminant concentrations. Variations in outside parameters will directly impact indoor air quality and residents' health. Numerical modeling can contribute to comprehend these various parameters because it allows full control of boundary conditions and sampling points. In this study, numerical weather prediction modeling was used to calculate wind profiles/distributions at the atmospheric scale, and computational fluid dynamics was used to model detailed urban and indoor flows, which were then integrated into a dynamic downscaling analysis to predict specific urban wind parameters from the atmospheric to built-environment scale. Wind velocity and contaminant concentration distributions inside a factory building were analyzed to assess the quality of the human working environment by using a computer simulated person. The impact of cross ventilation flows and its variations on local average contaminant concentration around a factory worker, and inhaled contaminant dose, were then discussed.

Airway humidification with a heat and moisture exchanger in mechanically ventilated neonates : a preliminary evaluation.

PubMed

Fassassi, Mikaïla; Michel, Fabrice; Thomachot, Laurent; Nicaise, Claire; Vialet, Renaud; Jammes, Yves; Lagier, Pierre; Martin, Claude

2007-02-01

We set out to evaluate the efficacy of passive inspiratory gas conditioning in mechanically ventilated neonates and compared it with that of a heated humidifier (HH). Prospective, randomized, controlled study. Neonatal and pediatric intensive care unit. Fourteen mechanically ventilated neonates nursed in incubators. The HH was set to deliver a temperature of 37 degrees C and an absolute humidity of 40 mgH(2)O/l at the incubator entrance. Inspired temperature (T degrees ) and absolute humidity (AH) were measured by the psychometric method, transpulmonary pressure (Tpres) by means of a differential pressure transducer. Measurements were performed at 5, 10, and 15 min. The values of T degrees were significantly higher using the HH (34.6+/-1.6 degrees C) than the heat and moisture exchanger (HME) (33.8+/2.3, p<0.001). The values of AH were significantly higher using the HH (36.6+/-2.5 mgH(2)O/l) than the HME (32.4+/-2.8 mgH(2)O/l, p<0.001). No significant changes were observed in transpulmonary pressure. A significant positive correlation was observed between incubator temperature and the temperature delivered by the HH (R(2)=0.61, p<0.001). The use of HMEs in neonates made it possible to achieve an absolute humidity of 28 mgH(2)O/l or more and a temperature of 30 degrees C or more. Higher values are obtained using a HH.

Impact of High-Intensity-NIV on the heart in stable COPD: a randomised cross-over pilot study.

PubMed

Duiverman, Marieke Leontine; Maagh, Petra; Magnet, Friederike Sophie; Schmoor, Claudia; Arellano-Maric, Maria Paola; Meissner, Axel; Storre, Jan Hendrik; Wijkstra, Peter Jan; Windisch, Wolfram; Callegari, Jens

2017-05-02

Although high-intensity non-invasive ventilation has been shown to improve outcomes in stable COPD, it may adversely affect cardiac performance. Therefore, the aims of the present pilot study were to compare cardiac and pulmonary effects of 6 weeks of low-intensity non-invasive ventilation and 6 weeks of high-intensity non-invasive ventilation in stable COPD patients. In a randomised crossover pilot feasibility study, the change in cardiac output after 6 weeks of each NIV mode compared to baseline was assessed with echocardiography in 14 severe stable COPD patients. Furthermore, CO during NIV, gas exchange, lung function, and health-related quality of life were investigated. Three patients dropped out: two deteriorated on low-intensity non-invasive ventilation, and one presented with decompensated heart failure while on high-intensity non-invasive ventilation. Eleven patients were included in the analysis. In general, cardiac output and NTproBNP did not change, although individual effects were noticed, depending on the pressures applied and/or the co-existence of heart failure. High-intensity non-invasive ventilation tended to be more effective in improving gas exchange, but both modes improved lung function and the health-related quality of life. Long-term non-invasive ventilation with adequate pressure to improve gas exchange and health-related quality of life did not have an overall adverse effect on cardiac performance. Nevertheless, in patients with pre-existing heart failure, the application of very high inspiratory pressures might reduce cardiac output. The trial was registered in the Deutsches Register Klinischer Studien (DRKS-ID: DRKS00007977 ).

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

Pulse pressure variation and prediction of fluid responsiveness in patients ventilated with low tidal volumes.

PubMed

Oliveira-Costa, Clarice Daniele Alves de; Friedman, Gilberto; Vieira, Sílvia Regina Rios; Fialkow, Léa

2012-07-01

To determine the utility of pulse pressure variation (ΔRESP PP) in predicting fluid responsiveness in patients ventilated with low tidal volumes (V T) and to investigate whether a lower ΔRESP PP cut-off value should be used when patients are ventilated with low tidal volumes. This cross-sectional observational study included 37 critically ill patients with acute circulatory failure who required fluid challenge. The patients were sedated and mechanically ventilated with a V T of 6-7 ml/kg ideal body weight, which was monitored with a pulmonary artery catheter and an arterial line. The mechanical ventilation and hemodynamic parameters, including ΔRESP PP, were measured before and after fluid challenge with 1,000 ml crystalloids or 500 ml colloids. Fluid responsiveness was defined as an increase in the cardiac index of at least 15%. ClinicalTrial.gov: NCT01569308. A total of 17 patients were classified as responders. Analysis of the area under the ROC curve (AUC) showed that the optimal cut-off point for ΔRESP PP to predict fluid responsiveness was 10% (AUC = 0.74). Adjustment of the ΔRESP PP to account for driving pressure did not improve the accuracy (AUC = 0.76). A ΔRESP PP ≥ 10% was a better predictor of fluid responsiveness than central venous pressure (AUC = 0.57) or pulmonary wedge pressure (AUC = 051). Of the 37 patients, 25 were in septic shock. The AUC for ΔRESP PP ≥ 10% to predict responsiveness in patients with septic shock was 0.484 (sensitivity, 78%; specificity, 93%). The parameter D RESP PP has limited value in predicting fluid responsiveness in patients who are ventilated with low tidal volumes, but a ΔRESP PP>10% is a significant improvement over static parameters. A ΔRESP PP ≥ 10% may be particularly useful for identifying responders in patients with septic shock.

Protective garment ventilation system

NASA Technical Reports Server (NTRS)

Lang, R. (Inventor)

1970-01-01

A method and apparatus for ventilating a protective garment, space suit system, and/or pressure suits to maintain a comfortable and nontoxic atmosphere within is described. The direction of flow of a ventilating and purging gas in portions of the garment may be reversed in order to compensate for changes in environment and activity of the wearer. The entire flow of the ventilating gas can also be directed first to the helmet associated with the garment.

High tidal volume decreases adult respiratory distress syndrome, atelectasis, and ventilator days compared with low tidal volume in pediatric burned patients with inhalation injury.

PubMed

Sousse, Linda E; Herndon, David N; Andersen, Clark R; Ali, Arham; Benjamin, Nicole C; Granchi, Thomas; Suman, Oscar E; Mlcak, Ronald P

2015-04-01

Inhalation injury, which is among the causes of acute lung injury and acute respiratory distress syndrome (ARDS), continues to represent a significant source of mortality in burned patients. Inhalation injury often requires mechanical ventilation, but the ideal tidal volume strategy is not clearly defined in burned pediatric patients. The aim of this study was to determine the effects of low and high tidal volume on the number of ventilator days, ventilation pressures, and incidence of atelectasis, pneumonia, and ARDS in pediatric burned patients with inhalation injury within 1 year post burn injury. From 1986 to 2014, inhalation injury was diagnosed by bronchoscopy in pediatric burned patients (n = 932). Patients were divided into 3 groups: unventilated (n = 241), high tidal volume (HTV, 15 ± 3 mL/kg, n = 190), and low tidal volume (LTV, 9 ± 3 mL/kg, n = 501). High tidal volume was associated with significantly decreased ventilator days (p < 0.005) and maximum positive end expiratory pressure (p < 0.0001) and significantly increased maximum peak inspiratory pressure (p < 0.02) and plateau pressure (p < 0.02) compared with those in patients with LTV. The incidence of atelectasis (p < 0.0001) and ARDS (p < 0.02) was significantly decreased with HTV compared with LTV. However, the incidence of pneumothorax was significantly increased in the HTV group compared with the LTV group (p < 0.03). High tidal volume significantly decreases ventilator days and the incidence of both atelectasis and ARDS compared with low tidal volume in pediatric burned patients with inhalation injury. Therefore, the use of HTV may interrupt sequences leading to lung injury in our patient population. Copyright © 2015 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Acute Effects of Continuous Positive Air way Pressure on Pulse Pressure in Chronic Heart Failure

PubMed Central

Quintão, Mônica; Chermont, Sérgio; Marchese, Luana; Brandão, Lúcia; Bernardez, Sabrina Pereira; Mesquita, Evandro Tinoco; Rocha, Nazareth de Novaes; Nóbrega, Antônio Claudio L.

2014-01-01

Background Patients with heart failure (HF) have left ventricular dysfunction and reduced mean arterial pressure (MAP). Increased adrenergic drive causes vasoconstriction and vessel resistance maintaining MAP, while increasing peripheral vascular resistance and conduit vessel stiffness. Increased pulse pressure (PP) reflects a complex interaction of the heart with the arterial and venous systems. Increased PP is an important risk marker in patients with chronic HF (CHF). Non-invasive ventilation (NIV) has been used for acute decompensated HF, to improve congestion and ventilation through both respiratory and hemodynamic effects. However, none of these studies have reported the effect of NIV on PP. Objective The objective of this study was to determine the acute effects of NIV with CPAP on PP in outpatients with CHF. Methods Following a double-blind, randomized, cross-over, and placebo-controlled protocol, twenty three patients with CHF (17 males; 60 ± 11 years; BMI 29 ± 5 kg/cm2, NYHA class II, III) underwent CPAP via nasal mask for 30 min in a recumbent position. Mask pressure was 6 cmH2O, whereas placebo was fixed at 0-1 cmH2O. PP and other non invasive hemodynamics variables were assessed before, during and after placebo and CPAP mode. Results CPAP decreased resting heart rate (Pre: 72 ± 9; vs. Post 5 min: 67 ± 10 bpm; p < 0.01) and MAP (CPAP: 87 ± 11; vs. control 96 ± 11 mmHg; p < 0.05 post 5 min). CPAP decreased PP (CPAP: 47 ± 20 pre to 38 ± 19 mmHg post; vs. control: 42 ± 12 mmHg, pre to 41 ± 18 post p < 0.05 post 5 min). Conclusion NIV with CPAP decreased pulse pressure in patients with stable CHF. Future clinical trials should investigate whether this effect is associated with improved clinical outcome. PMID:24676373

Noise in a Laboratory Animal Facility from the Human and Mouse Perspectives

PubMed Central

Reynolds, Randall P; Kinard, Will L; Degraff, Jesse J; Leverage, Ned; Norton, John N

2010-01-01

The current study was performed to understand the level of sound produced by ventilated racks, animal transfer stations, and construction equipment that mice in ventilated cages hear relative to what humans would hear in the same environment. Although the ventilated rack and animal transfer station both produced sound pressure levels above the ambient level within the human hearing range, the sound pressure levels within the mouse hearing range did not increase above ambient noise from either noise source. When various types of construction equipment were used 3 ft from the ventilated rack, the sound pressure level within the mouse hearing range was increased but to a lesser degree for each implement than were the sound pressure levels within the human hearing range. At more distant locations within the animal facility, sound pressure levels from the large jackhammer within the mouse hearing range decreased much more rapidly than did those in the human hearing range, indicating that less of the sound is perceived by mice than by humans. The relatively high proportion of low-frequency sound produced by the shot blaster, used without the metal shot that it normally uses to clean concrete, increased the sound pressure level above the ambient level for humans but did not increase sound pressure levels above ambient noise for mice at locations greater than 3 ft from inside of the cage, where sound was measured. This study demonstrates that sound clearly audible to humans in the animal facility may be perceived to a lesser degree or not at all by mice, because of the frequency content of the sound. PMID:20858361

Physiological effects and optimisation of nasal assist-control ventilation for patients with chronic obstructive pulmonary disease in respiratory failure

PubMed Central

Girault, C.; Chevron, V.; Richard, J. C.; Daudenthun, I.; Pasquis, P.; Leroy, J.; Bonmarchand, G.

1997-01-01

BACKGROUND: A study was undertaken to investigate the effects of non- invasive assist-control ventilation (ACV) by nasal mask on respiratory physiological parameters and comfort in acute on chronic respiratory failure (ACRF). METHODS: Fifteen patients with chronic obstructive pulmonary disease (COPD) were prospectively and randomly assigned to two non-invasive ventilation (NIV) sequences in spontaneous breathing (SB) and ACV mode. ACV settings were always optimised and therefore subsequently adjusted according to patient's tolerance and air leaks. RESULTS: ACV significantly decreased all the total inspiratory work of breathing (WOBinsp) parameters, pressure time product, and oesophageal pressure variation in comparison with SB mode. The ACV mode also resulted in a significant reduction in surface diaphragmatic electromyographic activity to 36% of the control values and significantly improved the breathing pattern. SB did not change the arterial blood gas tensions from baseline values whereas ACV significantly improved both the PaO2 from a mean (SD) of 8.45 (2.95) kPa to 13.31 (2.15) kPa, PaCO2 from 9.52 (1.61) kPa to 7.39 (1.39) kPa, and the pH from 7.32 (0.03) to 7.40 (0.07). The respiratory comfort was significantly lower with ACV than with SB. CONCLUSIONS: This study shows that the clinical benefit of non-invasive ACV in the management of ACRF in patients with COPD results in a reduced inspiratory muscle activity providing an improvement in breathing pattern and gas exchange. Despite respiratory discomfort, the muscle rest provided appears sufficient when ACV settings are optimised. 


 PMID:9337827

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.

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.

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.

Systolic blood pressure is superior to other haemodynamic predictors of outcome in community acquired pneumonia.

PubMed

Chalmers, J D; Singanayagam, A; Hill, A T

2008-08-01

Admission blood pressure (BP) assessment is a central component of severity assessment for community acquired pneumonia. The aim of this study was to establish which readily available haemodynamic measure on admission is most useful for predicting severity in patients admitted with community acquired pneumonia. A prospective observational study of patients admitted with community acquired pneumonia was conducted in Edinburgh, UK. The measurements compared were systolic and diastolic BP, mean arterial pressure and pulse pressure. The outcomes of interest were 30 day mortality and the requirement for mechanical ventilation and/or inotropic support. Admission systolic BP < 90 mm Hg, diastolic BP < or = 60 mm Hg, mean arterial pressure < 70 mm Hg and pulse pressure < or = 40 mm Hg were all associated with increased 30 day mortality and the need for mechanical ventilation and/or inotropic support on multivariate logistic regression. The AUC values for each predictor of 30 day mortality were as follows: systolic BP < 90 mm Hg 0.70; diastolic BP < or = 60 mm Hg 0.59; mean arterial pressure < 70 mm Hg 0.64; and pulse pressure < or = 40 mm Hg 0.60. The AUC values for each predictor of need for mechanical ventilation and/or inotropic support were as follows: systolic BP < 90 mm Hg 0.70; diastolic BP < or = 60 mm Hg 0.68; mean arterial pressure < 70 mm Hg 0.69; and pulse pressure < or = 40 mm Hg 0.59. A simplified CRB65 score containing systolic blood pressure < 90 mm Hg alone performed equally well to standard CRB65 score (AUC 0.76 vs 0.74) and to the standard CURB65 score (0.76 vs 0.76) for the prediction of 30 day mortality. The simplified CRB65 score was equivalent for prediction of mechanical ventilation and/or inotropic support to standard CRB65 (0.77 vs 0.77) and to CURB65 (0.77 vs 0.78). Systolic BP is superior to other haemodynamic predictors of 30 day mortality and need for mechanical ventilation and/or inotropic support in community acquired pneumonia. The CURB65 score can be simplified to a modified CRB65 score by omission of the diastolic BP criterion without compromising its accuracy.

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.

Transdiaphragmatic pressure in quadriplegic individuals ventilated by diaphragmatic pacemaker.

PubMed Central

Garrido-García, H.; Martín-Escribano, P.; Palomera-Frade, J.; Arroyo, O.; Alonso-Calderón, J. L.; Mazaira-Alvarez, J.

1996-01-01

BACKGROUND: Electrophrenic pacing can be used in the management of ventilatory failure in quadriplegic patients. A study was undertaken to determine the pattern of transdiaphragmatic pressure (PDI) during the conditioning phase of electrophrenic pacing to see if it had a possible role in optimising the process of conditioning. METHODS: The tidal volume (TV) and PDI were measured in a group of six quadriplegic patients commencing ventilation by low frequency pulse stimulation (7-10 Hz) and low respiratory rate stimulation (< 10 breaths/min). RESULTS: Tidal volume increased between baseline and month 1 (4.33 ml/kg, p < 0.001) and between months 1 and 2 (3.00 ml/kg, p < 0.05) and then stabilised. PDI was higher during bilateral diaphragmatic pacing (mean (SD) 1.73 (0.30) kPa) than with either left (1.15 (0.34) kPa) or right (0.86 (0.37) kPa) unilateral pacing. PDI varied throughout the observation period, probably by interaction between recovery of the diaphragmatic fibres and the pacing regimen. CONCLUSIONS: Patients with quadriplegia due to high spinal injury can be maintained with ventilation by continuous electrophrenic pacing. The control criteria used in this study for pacing were tidal volume and the patient's tolerance, and the PDI measurement did not contribute any additional information to help with managing the conditioning process. PMID:8733497

Influences of Duration of Inspiratory Effort, Respiratory Mechanics, and Ventilator Type on Asynchrony With Pressure Support and Proportional Assist Ventilation.

PubMed

Vasconcelos, Renata S; Sales, Raquel P; Melo, Luíz H de P; Marinho, Liégina S; Bastos, Vasco Pd; Nogueira, Andréa da Nc; Ferreira, Juliana C; Holanda, Marcelo A

2017-05-01

Pressure support ventilation (PSV) is often associated with patient-ventilator asynchrony. Proportional assist ventilation (PAV) offers inspiratory assistance proportional to patient effort, minimizing patient-ventilator asynchrony. The objective of this study was to evaluate the influence of respiratory mechanics and patient effort on patient-ventilator asynchrony during PSV and PAV plus (PAV+). We used a mechanical lung simulator and studied 3 respiratory mechanics profiles (normal, obstructive, and restrictive), with variations in the duration of inspiratory effort: 0.5, 1.0, 1.5, and 2.0 s. The Auto-Trak system was studied in ventilators when available. Outcome measures included inspiratory trigger delay, expiratory trigger asynchrony, and tidal volume (V T ). Inspiratory trigger delay was greater in the obstructive respiratory mechanics profile and greatest with a effort of 2.0 s (160 ms); cycling asynchrony, particularly delayed cycling, was common in the obstructive profile, whereas the restrictive profile was associated with premature cycling. In comparison with PSV, PAV+ improved patient-ventilator synchrony, with a shorter triggering delay (28 ms vs 116 ms) and no cycling asynchrony in the restrictive profile. V T was lower with PAV+ than with PSV (630 mL vs 837 mL), as it was with the single-limb circuit ventilator (570 mL vs 837 mL). PAV+ mode was associated with longer cycling delays than were the other ventilation modes, especially for the obstructive profile and higher effort values. Auto-Trak eliminated automatic triggering. Mechanical ventilation asynchrony was influenced by effort, respiratory mechanics, ventilator type, and ventilation mode. In PSV mode, delayed cycling was associated with shorter effort in obstructive respiratory mechanics profiles, whereas premature cycling was more common with longer effort and a restrictive profile. PAV+ prevented premature cycling but not delayed cycling, especially in obstructive respiratory mechanics profiles, and it was associated with a lower V T . Copyright © 2017 by Daedalus Enterprises.

Optimization of Endotracheal Tube Cuff Pressure by Monitoring CO2 Levels in the Subglottic Space in Mechanically Ventilated Patients: A Randomized Controlled Trial.

PubMed

Efrati, Shai; Bolotin, Gil; Levi, Leon; Zaaroor, Menashe; Guralnik, Ludmila; Weksler, Natan; Levinger, Uriel; Soroksky, Arie; Denman, William T; Gurman, Gabriel M

2017-10-01

Many of the complications of mechanical ventilation are related to inappropriate endotracheal tube (ETT) cuff pressure. The aim of the current study was to evaluate the effectiveness of automatic cuff pressure closed-loop control in patients under prolonged intubation, where presence of carbon dioxide (CO2) in the subglottic space is used as an indicator for leaks. The primary outcome of the study is leakage around the cuff quantified using the area under the curve (AUC) of CO2 leakage over time. This was a multicenter, prospective, randomized controlled, noninferiority trial including intensive care unit patients. All patients were intubated with the AnapnoGuard ETT, which has an extra lumen used to monitor CO2 levels in the subglottic space.The study group was connected to the AnapnoGuard system operating with cuff control adjusted automatically based on subglottic CO2 (automatic group). The control group was connected to the AnapnoGuard system, while cuff pressure was managed manually using a manometer 3 times/d (manual group). The system recorded around cuff CO2 leakage in both groups. Seventy-two patients were recruited and 64 included in the final analysis. The mean hourly around cuff CO2 leak (mm Hg AUC/h) was 0.22 ± 0.32 in the manual group and 0.09 ± 0.04 in the automatic group (P = .01) where the lower bound of the 1-sided 95% confidence interval was 0.05, demonstrating noninferiority (>-0.033). Additionally, the 2-sided 95% confidence interval was 0.010 to 0.196, showing superiority (>0.0) as well. Significant CO2 leakage (CO2 >2 mm Hg) was 0.027 ± 0.057 (mm Hg AUC/h) in the automatic group versus 0.296 ± 0.784 (mm Hg AUC/h) in the manual group (P = .025). In addition, cuff pressures were in the predefined safety range 97.6% of the time in the automatic group compared to 48.2% in the automatic group (P < .001). This study shows that the automatic cuff pressure group is not only noninferior but also superior compared to the manual cuff pressure group. Thus, the use of automatic cuff pressure control based on subglottic measurements of CO2 levels is an effective method for ETT cuff pressure optimization. The method is safe and can be easily utilized with any intubated patient.

Safety and effectiveness of alveolar recruitment maneuvers and positive end-expiratory pressure during general anesthesia for cesarean section: a prospective, randomized trial.

PubMed

Aretha, D; Fligou, F; Kiekkas, P; Messini, C; Panteli, E; Zintzaras, E; Karanikolas, M

2017-05-01

During cesarean section, the supine position reduces functional residual capacity and worsens lung compliance. We tested the hypothesis that alveolar recruitment maneuvers and positive end-expiratory pressure improve lung compliance in women undergoing general anesthesia for cesarean section. Ninety women undergoing cesarean section were randomly assigned to one of two groups in a prospective, double-blind trial. In the alveolar recruitment maneuver group, pressure-control ventilation was used and inspiratory time was increased to 50% after delivery; positive end-expiratory pressure was increased to 20cmH 2 O and peak airway inspiratory pressure gradually increased to 45-50cmH 2 O. Volume-control ventilation was then used with low tidal volumes (6mL/kg) and positive end-expiratory pressure was reduced stepwise to 8cmH 2 O. In the control group, alveolar recruitment maneuvers were not used. Data were collected before and 3, 10 and 20min after the alveolar recruitment maneuver, before extubation and postoperatively at 10 and 20min. Dynamic compliance, peak airway inspiratory pressure, PaO 2 and PaO 2 /FiO 2 were significantly different in the alveolar recruitment maneuver group compared to controls at all time points during surgery except at baseline. Oxygen saturation was significantly greater in the alveolar recruitment maneuver group at 10 and 20min and before extubation. Dynamic compliance was 29.7-42.5% higher and peak airway inspiratory pressure 3.6-10.2% lower in the alveolar recruitment maneuver group compared to controls. The PaO 2 , PaO 2 /FiO 2 and oxygen saturation were higher (9.4-12%, 10.3-11.9% and 0.4-1.3%, respectively) in the alveolar recruitment maneuver group. Postoperatively, PaO 2 and oxygen saturation were significantly higher in the alveolar recruitment maneuver group compared to controls (PaO 2 9.2% at 10min and 8.4% at 20min, oxygen saturation 0.8% at 10min and 1.1% at 20min). There were no significant differences in hemodynamic stability or adverse events between groups. Compared to standard care, the alveolar recruitment maneuver with positive end-expiratory pressure and low tidal volumes appears safe and effective in improving lung compliance and both intraoperative and postoperative oxygenation in women undergoing general anesthesia for elective cesarean section. Copyright © 2016 Elsevier Ltd. All rights reserved.

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.

Role of non-invasive ventilation (NIV) in the perioperative period.

PubMed

Jaber, Samir; Michelet, Pierre; Chanques, Gerald

2010-06-01

Anaesthesia, postoperative pain and surgery (more so if the site of the surgery approaches the diaphragm) will induce respiratory modifications: hypoxaemia, pulmonary volume decrease and atelectasis associated to a restrictive syndrome and a diaphragm dysfunction. These modifications of the respiratory function occur early after surgery and may induce acute respiratory failure (ARF). Maintenance of adequate oxygenation in the postoperative period is of major importance, especially when pulmonary complications such as ARF occur. Non-invasive ventilation (NIV) refers to techniques allowing respiratory support without the need of endotracheal intubation. Two types of NIV are commonly used: noninvasive continuous positive airway pressure (CPAP) and noninvasive positive pressure ventilation (NPPV) which delivers two levels of positive pressure (pressure support ventilation + positive end-expiratory pressure). NIV may be an important tool to prevent (prophylactic treatment) or to treat ARF avoiding intubation (curative treatment). The aims of NIV are: (1) to partially compensate for the affected respiratory function by reducing the work of breathing, (2) to improve alveolar recruitment with better gas exchange (oxygenation and ventilation) and (3) to reduce left ventricular after load increasing cardiac output and improving haemodynamics. Evidence suggests that NIV, as a prophylactic or curative treatment, has been proven to be an effective strategy to reduce intubation rates, nosocomial infections, intensive care unit and hospital lengths of stay, morbidity and mortality in postoperative patients. However, before initiating NIV, any surgical complication must be treated. The aims of this article are (1) to describe the rationale behind the application of NIV, (2) to report indications (including induction of anaesthesia) and contraindications and (3) to offer some algorithms for safe usage of NIV in high-risk surgery patients.

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.

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.

Noninvasive Positive Pressure Ventilation for Chronic Respiratory Failure Patients With Stable Chronic Obstructive Pulmonary Disease (COPD)

PubMed Central

2012-01-01

Executive Summary In July 2010, the Medical Advisory Secretariat (MAS) began work on a Chronic Obstructive Pulmonary Disease (COPD) evidentiary framework, an evidence-based review of the literature surrounding treatment strategies for patients with COPD. This project emerged from a request by the Health System Strategy Division of the Ministry of Health and Long-Term Care that MAS provide them with an evidentiary platform on the effectiveness and cost-effectiveness of COPD interventions. After an initial review of health technology assessments and systematic reviews of COPD literature, and consultation with experts, MAS identified the following topics for analysis: vaccinations (influenza and pneumococcal), smoking cessation, multidisciplinary care, pulmonary rehabilitation, long-term oxygen therapy, noninvasive positive pressure ventilation for acute and chronic respiratory failure, hospital-at-home for acute exacerbations of COPD, and telehealth (including telemonitoring and telephone support). Evidence-based analyses were prepared for each of these topics. For each technology, an economic analysis was also completed where appropriate. In addition, a review of the qualitative literature on patient, caregiver, and provider perspectives on living and dying with COPD was conducted, as were reviews of the qualitative literature on each of the technologies included in these analyses. The Chronic Obstructive Pulmonary Disease Mega-Analysis series is made up of the following reports, which can be publicly accessed at the MAS website at: http://www.hqontario.ca/en/mas/mas_ohtas_mn.html. Chronic Obstructive Pulmonary Disease (COPD) Evidentiary Framework Influenza and Pneumococcal Vaccinations for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Smoking Cessation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Community-Based Multidisciplinary Care for Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Pulmonary Rehabilitation for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Long-term Oxygen Therapy for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Noninvasive Positive Pressure Ventilation for Acute Respiratory Failure Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Noninvasive Positive Pressure Ventilation for Chronic Respiratory Failure Patients With Stable Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Hospital-at-Home Programs for Patients With Acute Exacerbations of Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Home Telehealth for Patients With Chronic Obstructive Pulmonary Disease (COPD): An Evidence-Based Analysis Cost-Effectiveness of Interventions for Chronic Obstructive Pulmonary Disease Using an Ontario Policy Model Experiences of Living and Dying With COPD: A Systematic Review and Synthesis of the Qualitative Empirical Literature For more information on the qualitative review, please contact Mita Giacomini at: http://fhs.mcmaster.ca/ceb/faculty_member_giacomini.htm. For more information on the economic analysis, please visit the PATH website: http://www.path-hta.ca/About-Us/Contact-Us.aspx. The Toronto Health Economics and Technology Assessment (THETA) collaborative has produced an associated report on patient preference for mechanical ventilation. For more information, please visit the THETA website: http://theta.utoronto.ca/static/contact. Objective The objective of this health technology assessment was to determine the effectiveness and cost-effectiveness of noninvasive ventilation for stable chronic obstructive pulmonary disease (COPD). Clinical Need: Condition and Target Population Noninvasive ventilation is used for COPD patients with chronic respiratory failure. Chronic respiratory failure in COPD patients may be due to the inability of the pulmonary system to coordinate ventilation, leading to adverse arterial levels of oxygen and carbon dioxide. Noninvasive ventilation in stable COPD patients has the potential to improve quality of life, prolong survival, and improve gas exchange and sleep quality in patients who are symptomatic after optimal therapy, have hypercapnia or nocturnal hypoventilation and mild hypercapnia, and are frequently hospitalized. Technology Noninvasive positive pressure ventilation (NPPV) is any form of positive ventilatory support without the use of an endotracheal tube. For stable COPD, the standard of care when using noninvasive ventilation is bilevel positive airway pressure (BiPAP). Bilevel positive airway pressure involves both inspiratory and expiratory pressure, high during inspiration and lower during expiration. It acts as a pressure support to accentuate a patient’s inspiratory efforts. The gradient between pressures maintains alveolar ventilation and helps to reduce carbon dioxide levels. Outpatients typically use BiPAP at night. Additional advantages of using BiPAP include resting of respiratory muscles, decreased work of breathing, and control of obstructive hypopnea. Research Question What is the effectiveness and cost-effectiveness of noninvasive ventilation, compared with no ventilation while receiving usual care, for stable COPD patients? Research Methods Literature Search Search Strategy A literature search was performed on December 3, 2010, using OVID MEDLINE, OVID MEDLINE In-Process and Other Non-Indexed Citations, OVID EMBASE, EBSCO Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Wiley Cochrane Library, and the Centre for Reviews and Dissemination database for studies published from January 1, 2004 to December 3, 2010. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any additional relevant studies not identified through the search. When the reviewer was unsure of the eligibility of articles, a second clinical epidemiologist and then a group of epidemiologists reviewed these until consensus was reached. Inclusion Criteria full-text English language articles, studies published between January 1, 2004 and December 3, 2010, journal articles that report on the effectiveness or cost-effectiveness of noninvasive ventilation, clearly described study design and methods, and health technology assessments, systematic reviews, meta-analyses, randomized controlled trials (RCTs). Exclusion Criteria non-English papers animal or in vitro studies case reports, case series, or case-case studies cross-over RCTs studies on noninvasive negative pressure ventilation (e.g., iron lung) studies that combine ventilation therapy with other regimens (e.g., daytime NPPV plus exercise or pulmonary rehabilitation) studies on heliox with NPPV studies on pulmonary rehabilitation with NPPV Outcomes of Interest mortality/survival hospitalizations/readmissions length of stay in hospital forced expiratory volume arterial partial pressure of oxygen arterial partial pressure of carbon dioxide dyspnea exercise tolerance health-related quality of life Note: arterial pressure of oxygen and carbon dioxide are surrogate outcomes. Statistical Methods A meta-analysis and an analysis of individual studies were performed using Review Manager Version 5. For continuous data, a mean difference was calculated, and for dichotomous data, a relative risk ratio was calculated for RCTs. For continuous variables with mean baseline and mean follow-up data, a change value was calculated as the difference between the 2 mean values. Quality of Evidence The quality of each included study was assessed taking into consideration allocation concealment, randomization, blinding, power/sample size, withdrawals/dropouts, and intention-to-treat analyses. The quality of the body of evidence was assessed as high, moderate, low, or very low according to the GRADE Working Group criteria. The following definitions of quality were used in grading the quality of the evidence: High Further research is very unlikely to change confidence in the estimate of effect. Moderate Further research is likely to have an important impact on confidence in the estimate of effect and may change the estimate. Low Further research is very likely to have an important impact on confidence in the estimate of effect and is likely to change the estimate. Very Low Any estimate of effect is very uncertain Summary of Findings Conclusions The following conclusions refer to stable, severe COPD patients receiving usual care. Short-Term Studies Based on low quality of evidence, there is a beneficial effect of NPPV compared with no ventilation on oxygen gas exchange, carbon dioxide gas exchange, and exercise tolerance measured using the 6 Minute Walking Test. Based on very low quality of evidence, there is no effect of NPPV therapy on lung function measured as forced expiratory volume in 1 second (Type II error not excluded). Long-Term Studies Based on moderate quality of evidence, there is no effect of NPPV therapy for the outcomes of mortality, lung function measured as forced expiratory volume in 1 second, and exercise tolerance measured using the 6 Minute Walking Test. Based on low quality of evidence, there is no effect of NPPV therapy for the outcomes of oxygen gas exchange and carbon dioxide gas exchange (Type II error not excluded). Qualitative Assessment Based on low quality of evidence, there is a beneficial effect of NPPV compared with no ventilation for dyspnea based on reduced Borg score or Medical Research Council dyspnea score. Based on moderate quality of evidence, there is no effect of NPPV therapy for hospitalizations. Health-related quality of life could not be evaluated. PMID:23074437

Pulmonary function in patients with Huntington’s Disease

PubMed Central

2014-01-01

Background Huntington’s disease (HD) is a neurodegenerative disorder characterized by progressive motor, cognitive and psychiatric disturbances. Chest muscle rigidity, respiratory muscle weakness, difficulty in clearing airway secretions and swallowing abnormalities have been described in patients with neurodegenerative disorders including HD. However limited information is available regarding respiratory function in HD patients. The purpose of this study was to investigate pulmonary function of patients with HD in comparison to healthy volunteers, and its association with motor severity. Methods Pulmonary function measures were taken from 18 (11 male, 7 female) manifest HD patients (53 ± 10 years), and 18 (10 male, 8 female) healthy volunteers (52 ± 11 years) with similar anthropometric and life-style characteristics to the recruited HD patients. Motor severity was quantified by the Unified Huntington’s Disease Rating Scale-Total Motor Score (UHDRS-TMS). Maximum respiratory pressure was measured on 3 separate days with a week interval to assess test-retest reliability. Results The test-retest reliability of maximum inspiratory and expiratory pressure measurements was acceptable for both HD patient and control groups (ICC ≥0.92), but the values over 3 days were more variable in the HD group (CV < 11.1%) than in the control group (CV < 7.6%). The HD group showed lower respiratory pressure, forced vital capacity, peak expiratory flow and maximum voluntary ventilation than the control group (p < 0.05). Forced vital capacity, maximum voluntary ventilation and maximum respiratory pressures were negatively (r = -0.57; -0.71) correlated with the UHDRS-TMS (p < 0.05). Conclusion Pulmonary function is decreased in manifest HD patients, and the magnitude of the decrease is associated with motor severity. PMID:24886346

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.

Effects of Increasing Airway Pressures on the Pressure of the Endotracheal Tube Cuff During Pelvic Laparoscopic Surgery.

PubMed

Rosero, Eric B; Ozayar, Esra; Eslava-Schmalbach, Javier; Minhajuddin, Abu; Joshi, Girish P

2017-11-17

Tracheal tube cuff pressures exceeding the perfusion pressures of the tracheal mucosa have been associated with complications such as sore throat, tracheal mucosa ulcers, tracheal rupture, and subglottic stenosis. Despite appropriate inflation, many factors can increase the tracheal cuff pressure during mechanical ventilation. This prospective observational cohort study was designed to test the hypothesis that during a clinical model of decreasing respiratory compliance, the pressure within the endotracheal tube cuff will rise in direct relationship to increases in the airway pressures. Twenty-eight adult obese patients (BMI ≥30 kg/m) scheduled for elective laparoscopic gynecologic procedures were enrolled. All patients received general anesthesia utilizing endotracheal tubes with low-pressure high-volume cuffs. After baseline adjustment of the cuff pressure to 25 cm H2O, the airway pressures and endotracheal cuff pressures were continuously measured using pressure transducers connected to the anesthesia circuit and cuff pilot, respectively. Data on cuff and airway pressures, mechanical ventilation parameters, intraabdominal pressures, and degree of surgical table inclination were collected throughout the anesthetic procedure. General linear regression models with fixed and random effects were fit to assess the effect of increases in airway pressures on cuff pressure, after adjusting for covariates and the clustered structure of the data. The mean (standard deviation) age and body mass index were 42.2 (8.8) years and 37.7 (5.1) kg/m, respectively. After tracheal intubation, the cuffs were overinflated (ie, intracuff pressures >30 cm H2O) in 89% of patients. The cuff pressures significantly changed after concomitant variations in the airway pressures from a mean (standard error) value of 29.6 (1.30) cm H2O before peritoneal insufflations, to 35.6 (0.68) cm H2O after peritoneal insufflation, and to 27.8 (0.79) cm H2O after peritoneal deflation (P < .0001). The multilevel mixed regression models revealed that after controlling for clustering of the data (at the patient and study phase levels) and covariates, increased peak airway pressures were significantly associated with increased pressures within the endotracheal cuff (coefficient [95% confidence interval], 0.25 [0.14-0.36]; P < .0001). Other variables associated with increasing endotracheal cuff pressure included degree of surgical table inclination (0.08 [0.04-0.12]; P = .0003) and I:E ratio of 1:1 (4.47 [2.10-6.83]; P = .0002). This clinical model of decreased respiratory compliance in mechanically ventilated patients reveals that the pressure within the endotracheal cuff significantly changes in direct relation to changes in the airway pressures. This finding may have clinical relevance in patients requiring prolonged use of high airway pressures.

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

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

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.

System Design Verification for Closed Loop Control of Oxygenation With Concentrator Integration.

PubMed

Gangidine, Matthew M; Blakeman, Thomas C; Branson, Richard D; Johannigman, Jay A

2016-05-01

Addition of an oxygen concentrator into a control loop furthers previous work in autonomous control of oxygenation. Software integrates concentrator and ventilator function from a single control point, ensuring maximum efficiency by placing a pulse of oxygen at the beginning of the breath. We sought to verify this system. In a test lung, fraction of inspired oxygen (FIO2) levels and additional data were monitored. Tests were run across a range of clinically relevant ventilator settings in volume control mode, for both continuous flow and pulse dose flow oxygenation. Results showed the oxygen concentrator could maintain maximum pulse output (192 mL) up to 16 breaths per minute. Functionality was verified across ranges of tidal volumes and respiratory rates, with and without positive end-expiratory pressure, in continuous flow and pulse dose modes. For a representative test at respiratory rate 16 breaths per minute, tidal volume 550 mL, without positive end-expiratory pressure, pulse dose oxygenation delivered peak FIO2 of 76.83 ± 1.41%, and continuous flow 47.81 ± 0.08%; pulse dose flow provided a higher FIO2 at all tested setting combinations compared to continuous flow (p < 0.001). These tests verify a system that provides closed loop control of oxygenation while integrating time-coordinated pulse-doses from an oxygen concentrator. This allows the most efficient use of resources in austere environments. Reprint & Copyright © 2016 Association of Military Surgeons of the U.S.

ASSESSMENT of POTENTIAL CARBON DIOXIDE-BASED DEMAND CONTROL VENTILATION SYSTEM PERFORMANCE in SINGLE ZONE SYSTEMS

DTIC Science & Technology

2013-03-21

and timers use a time-based estimate to predict how many people are in a facility at a given point in the day. CO2-based DCV systems measure CO2...energy and latent energy from the outside air when the coils’ surface temperature is below the dew point of the air passing over the coils (ASHRAE...model assumes that the dew point water saturation pressure is the same as the dry-bulb water vapor pressure, consistent with a typical ASHRAE

Acute hemodynamic effects of adaptive servo-ventilation in patients with heart failure.

PubMed

Yamada, Shiro; Sakakibara, Mamoru; Yokota, Takashi; Kamiya, Kiwamu; Asakawa, Naoya; Iwano, Hiroyuki; Yamada, Satoshi; Oba, Koji; Tsutsui, Hiroyuki

2013-01-01

Adaptive servo-ventilation (ASV) improves cardiac function in patients with heart failure (HF). We compared the hemodynamics of control and HF patients, and identified the predictors for acute effects of ASV in HF. We performed baseline echocardiographic measurements and hemodynamic measurements at baseline and after 15 min of ASV during cardiac catheterization in 11 control and 34 HF patients. Heart rate and blood pressure did not change after ASV in either the control or HF group. Stroke volume index (SVI) decreased from 49.3±7.6 to 41.3±7.6 ml/m2 in controls (P<0.0001) but did not change in the HF patients (from 34.8±11.5 to 32.8±8.9 ml/m2, P=0.148). In the univariate analysis, pulmonary capillary wedge pressure (PCWP), mitral regurgitation (MR)/left atrial (LA) area, E/A, E/e', and the sphericity index defined by the ratio between the short-axis and long-axis dimensions of the left ventricle significantly correlated with % change of SVI from baseline during ASV. PCWP and MR/LA area were independent predictors by multivariate analysis. Moreover, responders (15 of 34 HF patients; 44%) categorized by an increase in SVI showed significantly higher PCWP, MR, and sphericity index. Left ventricular structure and MR, as well as PCWP, could predict acute favorable effects on hemodynamics by ASV therapy in HF patients. 

Experimental system for the control of surgically induced infections

NASA Technical Reports Server (NTRS)

Tevebaugh, M. D.

1971-01-01

The development tests to be performed on the experimental system are described in detail. The test equipment, conditions, and procedures are given. The portable clean room tests include assembly, collapsability, portability, and storage; laminar flow rate; static pressure; air flow pattern; and electrostatic buildup. The other tests are on the ventilation system, human factors evaluation, electrical subsystem, and material compatibility.

[Cost-consequence analysis of respiratory preventive intervention among institutionalized older people: randomized controlled trial].

PubMed

Cebrià I Iranzo, Maria Dels Àngels; Tortosa-Chuliá, M Ángeles; Igual-Camacho, Celedonia; Sancho, Patricia; Galiana, Laura; Tomás, José Manuel

2014-01-01

The institutionalized elderly with functional impairment show a greater decline in respiratory muscle (RM) function. The aims of the study are to evaluate outcomes and costs of RM training using Pranayama in institutionalized elderly people with functional impairment. A randomized controlled trial was conducted on institutionalized elderly people with walking limitation (n=54). The intervention consisted of 6 weeks of Pranayama RM training (5 times/week). The outcomes were measured at 4 time points, and were related to RM function: the maximum respiratory pressures and the maximum voluntary ventilation. Perceived satisfaction in the experimental group (EG) was assessed by means of an ad hoc questionnaire. Direct and indirect costs were estimated from the social perspective. The GE showed a significant improvement related with strength (maximum respiratory pressures) and endurance (maximum voluntary ventilation) of RM. Moreover, 92% of the EG reported a high satisfaction. The total social costs, direct and indirect, amounted to Euro 21,678. This evaluation reveals that RM function improvement is significant, that intervention is well tolerated and appreciated by patients, and the intervention costs are moderate. Copyright © 2013 SEGG. Published by Elsevier Espana. All rights reserved.

Ventilatory responses to acute and chronic hypoxia are altered in female but not male Paskin-deficient mice.

PubMed

Soliz, Jorge; Soulage, Christophe; Borter, Emanuela; van Patot, Martha Tissot; Gassmann, Max

2008-08-01

Proteins harboring a Per-Arnt-Sim (PAS) domain are versatile and allow archaea, bacteria, and plants to sense oxygen partial pressure, as well as light intensity and redox potential. A PAS domain associated with a histidine kinase domain is found in FixL, the oxygen sensor molecule of Rhizobium species. PASKIN is the mammalian homolog of FixL, but its function is far from being understood. Using whole body plethysmography, we evaluated the ventilatory response to acute and chronic hypoxia of homozygous deficient male and female PASKIN mice (Paskin-/-). Although only slight ventilatory differences were found in males, female Paskin-/- mice increased ventilatory response to acute hypoxia. Unexpectedly, females had an impaired ability to reach ventilatory acclimatization in response to chronic hypoxia. Central control of ventilation occurs in the brain stem respiratory centers and is modulated by catecholamines via tyrosine hydroxylase (TH) activity. We observed that TH activity was altered in male and female Paskin-/- mice. Peripheral chemoreceptor effects on ventilation were evaluated by exposing animals to hyperoxia (Dejours test) and domperidone, a peripheral ventilatory stimulant drug directly affecting the carotid sinus nerve discharge. Male and female Paskin-/- had normal peripheral chemosensory (carotid bodies) responses. In summary, our observations suggest that PASKIN is involved in the central control of hypoxic ventilation, modulating ventilation in a gender-dependent manner.