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Sample records for refereeris peep kngas

  1. Recruitment Maneuvers and PEEP Titration.

    PubMed

    Hess, Dean R

    2015-11-01

    The injurious effects of alveolar overdistention are well accepted, and there is little debate regarding the importance of pressure and volume limitation during mechanical ventilation. The role of recruitment maneuvers is more controversial. Alveolar recruitment is desirable if it can be achieved, but the potential for recruitment is variable among patients with ARDS. A stepwise recruitment maneuver, similar to an incremental PEEP titration, is favored over sustained inflation recruitment maneuvers. Many approaches to PEEP titration have been proposed, and the best method to choose the most appropriate level for an individual patient is unclear. A PEEP level should be selected that balances alveolar recruitment against overdistention. The easiest approach to select PEEP might be according to the severity of the disease: 5-10 cm H2O PEEP in mild ARDS, 10-15 cm H2O PEEP in moderate ARDS, and 15-20 cm H2O PEEP in severe ARDS. Recruitment maneuvers and PEEP should be used within the context of lung protection and not just as a means of improving oxygenation. Copyright © 2015 by Daedalus Enterprises.

  2. Profound bradycardia with decreased PEEP.

    PubMed

    Wilcox, Susan R; Kansagra, Ankit; Richards, Jeremy B

    2013-11-01

    An athletic 21-year-old male was admitted to the surgical ICU after sustaining 2 stab wounds to his torso. He had an episode of left lung collapse early in his course, managed with suctioning and increased PEEP, to 15 cm H2O. He was bradycardic (heart rates 50-60 beats/min) throughout his ICU stay, but when the PEEP was lowered to 5 cm H2O in preparation for extubation, he developed sinus pauses and his heart rate dropped to 20 beats/min. After a thorough evaluation, the drop in his heart rate was determined to be due to increased vagal tone from increased cardiac output with the decreased PEEP. After premedication with glycopyrrolate, he was successfully extubated the following day, while his heart rate remained at his baseline of 50 beats/min. We review the physiologic mechanisms of bradycardia due to the removal of mechanical ventilation.

  3. Peeps at William Edwin Hamilton

    NASA Astrophysics Data System (ADS)

    Wayman, P. A.

    1999-01-01

    William Edwin Hamilton, 1834-1902, (WEH) was the elder son of Sir William Rowan Hamilton and Helen Hamilton and he inherited many of the characteristics of his famous father. One property that he did not inherit, however, was his father's genius. While the outline of the life of WEH was given by Hankins in his 1980 biography of Sir William, a copy of ``Peeps at My Life'' written by WEH during the last months of his life was not available until recently. A few years ago a copy was sent to me by Herman Berg of Detroit and in this article, the principal items in ``Peeps'' that are relevant to Ireland, and some other facets of the character of WEH, are included as they give an unusual viewpoint of a by-gone age.

  4. Effect of external PEEP in patients under controlled mechanical ventilation with an auto-PEEP of 5 cmH2O or higher.

    PubMed

    Natalini, Giuseppe; Tuzzo, Daniele; Rosano, Antonio; Testa, Marco; Grazioli, Michele; Pennestrì, Vincenzo; Amodeo, Guido; Berruto, Francesco; Fiorillo, Marialinda; Peratoner, Alberto; Tinnirello, Andrea; Filippini, Matteo; Marsilia, Paolo F; Minelli, Cosetta; Bernardini, Achille

    2016-12-01

    In some patients with auto-positive end-expiratory pressure (auto-PEEP), application of PEEP lower than auto-PEEP maintains a constant total PEEP, therefore reducing the inspiratory threshold load without detrimental cardiovascular or respiratory effects. We refer to these patients as "complete PEEP-absorbers." Conversely, adverse effects of PEEP application could occur in patients with auto-PEEP when the total PEEP rises as a consequence. From a pathophysiological perspective, all subjects with flow limitation are expected to be "complete PEEP-absorbers," whereas PEEP should increase total PEEP in all other patients. This study aimed to empirically assess the extent to which flow limitation alone explains a "complete PEEP-absorber" behavior (i.e., absence of further hyperinflation with PEEP), and to identify other factors associated with it. One hundred patients with auto-PEEP of at least 5 cmH2O at zero end-expiratory pressure (ZEEP) during controlled mechanical ventilation were enrolled. Total PEEP (i.e., end-expiratory plateau pressure) was measured both at ZEEP and after applied PEEP equal to 80 % of auto-PEEP measured at ZEEP. All measurements were repeated three times, and the average value was used for analysis. Forty-seven percent of the patients suffered from chronic pulmonary disease and 52 % from acute pulmonary disease; 61 % showed flow limitation at ZEEP, assessed by manual compression of the abdomen. The mean total PEEP was 7 ± 2 cmH2O at ZEEP and 9 ± 2 cmH2O after the application of PEEP (p < 0.001). Thirty-three percent of the patients were "complete PEEP-absorbers." Multiple logistic regression was used to predict the behavior of "complete PEEP-absorber." The best model included a respiratory rate lower than 20 breaths/min and the presence of flow limitation. The predictive ability of the model was excellent, with an overoptimism-corrected area under the receiver operating characteristics curve of 0.89 (95 % CI 0

  5. Assessment of Factors Related to Auto-PEEP.

    PubMed

    Natalini, Giuseppe; Tuzzo, Daniele; Rosano, Antonio; Testa, Marco; Grazioli, Michele; Pennestrì, Vincenzo; Amodeo, Guido; Marsilia, Paolo F; Tinnirello, Andrea; Berruto, Francesco; Fiorillo, Marialinda; Filippini, Matteo; Peratoner, Alberto; Minelli, Cosetta; Bernardini, Achille

    2016-02-01

    Previous physiological studies have identified factors that are involved in auto-PEEP generation. In our study, we examined how much auto-PEEP is generated from factors that are involved in its development. One hundred eighty-six subjects undergoing controlled mechanical ventilation with persistent expiratory flow at the beginning of each inspiration were enrolled in the study. Volume-controlled continuous mandatory ventilation with PEEP of 0 cm H2O was applied while maintaining the ventilator setting as chosen by the attending physician. End-expiratory and end-inspiratory airway occlusion maneuvers were performed to calculate respiratory mechanics, and tidal flow limitation was assessed by a maneuver of manual compression of the abdomen. The variable with the strongest effect on auto-PEEP was flow limitation, which was associated with an increase of 2.4 cm H2O in auto-PEEP values. Moreover, auto-PEEP values were directly related to resistance of the respiratory system and body mass index and inversely related to expiratory time/time constant. Variables that were associated with the breathing pattern (tidal volume, frequency minute ventilation, and expiratory time) did not show any relationship with auto-PEEP values. The risk of auto-PEEP ≥5 cm H2O was increased by flow limitation (adjusted odds ratio 17; 95% CI: 6-56.2), expiratory time/time constant ratio <1.85 (12.6; 4.7-39.6), respiratory system resistance >15 cm H2O/L s (3; 1.3-6.9), age >65 y (2.8; 1.2-6.5), and body mass index >26 kg/m(2) (2.6; 1.1-6.1). Flow limitation, expiratory time/time constant, resistance of the respiratory system, and obesity are the most important variables that affect auto-PEEP values. Frequency expiratory time, tidal volume, and minute ventilation were not independently associated with auto-PEEP. Therapeutic strategies aimed at reducing auto-PEEP and its adverse effects should be primarily oriented to the variables that mainly affect auto-PEEP values. Copyright © 2016 by

  6. The Crazy Business of Internet Peeping, Privacy, and Anonymity.

    ERIC Educational Resources Information Center

    Van Horn, Royal

    2000-01-01

    Peeping software takes several forms and can be used on a network or to monitor a certain computer. E-Mail Plus, for example, hides inside a computer and sends exact copies of incoming or outgoing e-mail anywhere. School staff with monitored computers should demand e-mail privacy. (MLH)

  7. Is There Any Association between PEEP and Upper Extremity DVT?

    PubMed Central

    Gupta, Ena; Siddiqi, Furqan; Faisal, Muhammad; Jones, Lisa M.; Louis, Mariam; Cury, James D.; Bajwa, Abubakr A.

    2015-01-01

    Background. We hypothesized that positive end-exploratory pressure (PEEP) may promote venous stasis in the upper extremities and predispose to upper extremity deep vein thrombosis (UEDVT). Methods. We performed a retrospective case control study of medical intensive care unit patients who required mechanical ventilation (MV) for >72 hours and underwent duplex ultrasound of their upper veins for suspected DVT between January 2011 and December 2013. Results. UEDVT was found in 32 (28.5%) of 112 patients. Nineteen (67.8%) had a central venous catheter on the same side. The mean ± SD duration of MV was 13.2 ± 9.5 days. Average PEEP was 7.13 ± 2.97 cm H2O. Average PEEP was ≥10 cm H2O in 23 (20.5%) patients. Congestive heart failure (CHF) significantly increased the odds of UEDVT (OR 4.53, 95% CI 1.13–18.11; P = 0.03) whereas longer duration of MV (≥13 vs. <13 days) significantly reduced it (OR 0.29, 95% CI 0.11–0.8; P = 0.02). Morbid obesity showed a trend towards significance (OR 3.82, 95% CI 0.95–15.4; P = 0.06). Neither PEEP nor any of the other analyzed predictors was associated with UEDVT. Conclusions. There is no association between PEEP and UEDVT. CHF may predispose to UEDVT whereas the risk of UEDVT declines with longer duration of MV. PMID:25922762

  8. Reliability of two common PEEP-generating devices used in neonatal resuscitation.

    PubMed

    Kelm, M; Proquitté, H; Schmalisch, G; Roehr, C C

    2009-12-01

    Approximately 15% of neonates require respiratory support at birth, the demand of which increases with decreasing gestational age. Positive end-expiratory pressure (PEEP) stabilizes the airways and improves both pulmonary functional residual capacity and compliance. Self-inflating bags, which can be used with and without a PEEP-valve, are most commonly used for neonatal resuscitation, pressure limited T-piece resuscitators are becoming increasingly popular. The aim of the study was to investigate the reliability of PEEP provision of both systems. An intubated, leak free mannequin (equivalent to 1 kg neonate, pulmonary compliance 0.2 ml*cmH (2)O (-1)) was used for testing both devices. Eleven PEEP-valves attached to a 240 ml self-inflating bag and 5 T-piece resuscitators were investigated. Provision of a PEEP of 5 cmH (2)O (gas flow of 8l/min) at manual ventilation at breaths 40/min was investigated. Data were recorded using a standard pneumotachograph. Only 1/11 PEEP-valves provided a PEEP of 5 cmH (2)O (mean (SD) 2.95 (1.82) cmH (2)O, CV 0.62%), in 5/11 (45%) PEEP was <3 cmH (2)O, in 2 of the PEEP-valves produced a PEEP below 0.3 cmH (2)O. All T-piece resuscitators provided a PEEP >5 cmH (2)O (mean 5.59 (0.32) cmH (2)O, CV 0.06%). Significant differences in individual performance per device (p<0.05) and between systems (p=0.007) were found. Self-inflating bags did not reliably provide the desired PEEP of 5 cmH (2)O, whereas T-piece resuscitators did reliably provide the set PEEP-level, with less variability. When using self-inflating bags with PEEP-valves, neonatologists should check the equipment regarding the reliability of PEEP provision. (c) Georg Thieme Verlag KG Stuttgart New York.

  9. Effects of Different Peep Levels on Mesenteric Leukocyte-Endothelial Interactions in Rats During Mechanical Ventilation

    PubMed Central

    Aikawa, Priscila; Farsky, Sandra Helena Poliselli; de Oliveira, Maria Aparecida; Pazetti, Rogério; Mauad, Thaís; Sannomiya, Paulina; Nakagawa, Naomi Kondo

    2009-01-01

    INTRODUCTION: Mechanical ventilation with positive end expiratory pressure (PEEP) improves oxygenation and treats acute pulmonary failure. However, increased intrathoracic pressure may cause regional blood flow alterations that may contribute to mesenteric ischemia and gastrointestinal failure. We investigated the effects of different PEEP levels on mesenteric leukocyte-endothelial interactions. METHODS: Forty-four male Wistar rats were initially anesthetized (Pentobarbital I.P. 50mg/kg) and randomly assigned to one of the following groups: 1) NAIVE (only anesthesia; n=9), 2) PEEP 0 (PEEP of 0 cmH2O, n=13), 3) PEEP 5 (PEEP of 5 cmH2O, n=12), and 4) PEEP 10 (PEEP of 10 cmH2O, n=13). Positive end expiratory pressure groups were tracheostomized and mechanically ventilated with a tidal volume of 10 mL/kg, respiratory rate of 70 rpm, and inspired oxygen fraction of 1. Animals were maintained under isoflurane anesthesia. After two hours, laparotomy was performed, and leukocyte-endothelial interactions were evaluated by intravital microscopy. RESULTS: No significant changes were observed in mean arterial blood pressure among groups during the study. Tracheal peak pressure was smaller in PEEP 5 compared with PEEP 0 and PEEP 10 groups (11, 15, and 16 cmH2O, respectively; p<0.05). After two hours of MV, there were no differences among NAIVE, PEEP 0 and PEEP 5 groups in the number of rollers (118±9,127±14 and 147±26 cells/10minutes, respectively), adherent leukocytes (3±1,3±1 and 4±2 cells/100μm venule length, respectively), and migrated leukocytes (2±1,2±1 and 2±1 cells/5,000μm2, respectively) at the mesentery. However, the PEEP 10 group exhibited an increase in the number of rolling, adherent and migrated leukocytes (188±15 cells / 10 min, 8±1 cells / 100 μm and 12±1 cells / 5,000 μm2, respectively; p<0.05). CONCLUSIONS: High intrathoracic pressure was harmful to mesenteric microcirculation in the experimental model of rats with normal lungs and stable

  10. Hyperdynamic sepsis modifies a PEEP-mediated redistribution in organ blood flows

    SciTech Connect

    Bersten, A.D.; Gnidec, A.A.; Rutledge, F.S.; Sibbald, W.J. )

    1990-05-01

    Changes in organ blood flow (Q) produced by 20 cm H2O positive end-expiratory pressure (PEEP) were measured before and after the induction of hyperdynamic sepsis in nine unanesthetized sheep. During the baseline nonseptic study, PEEP was associated with a 9% fall in thermodilution-measured systemic Q, although arterial perfusing pressures were unaffected. Concurrently, microsphere-derived Q was maintained to the brain and heart, but fell to liver, spleen, pancreas, kidney, large intestine, and gastrocnemius. Twenty-four to 36 h after cecal ligation and perforation, a pre-PEEP septic study demonstrated an increase in all of the cardiac index (CI) and systemic O2 delivery when compared with the nonseptic study, whereas whole-body O2 extraction was depressed. Although PEEP depressed systemic Q during the septic study to a greater extent than during the nonseptic study (p less than 0.02), absolute organ Q fell only to pancreas, liver, and spleen. Relative to the simultaneous fall in the CI, Q to some splanchnic organs was not depressed by PEEP to the same magnitude in the septic as in the nonseptic study. When an infusion of Ringer's lactate subsequently restored systemic Q to pre-PEEP septic levels, individual flows that had been depressed by PEEP were not restored. Furthermore, Q-kidney continued to fall, such that the postfluid Q-kidney (-19%) was significantly less than was demonstrated in the pre-PEEP septic study. We postulate that differences noted in the distribution of organ Q between the nonseptic and hyperdynamic septic studies after the application of PEEP were secondary to the vasculopathy of sepsis and/or an alteration in the function of specific organ microcirculations. However, these data do not address whether the changes in organ Q distribution after a PEEP-mediated depression in systemic Q during sepsis significantly restricted tissue DO2.

  11. Double-lumen tubes and auto-PEEP during one-lung ventilation.

    PubMed

    Spaeth, J; Ott, M; Karzai, W; Grimm, A; Wirth, S; Schumann, S; Loop, T

    2016-01-01

    Double-lumen tubes (DLT) are routinely used to enable one-lung-ventilation (OLV) during thoracic anaesthesia. The flow-dependent resistance of the DLT's bronchial limb may be high as a result of its narrow inner diameter and length, and thus potentially contribute to an unintended increase in positive end-expiratory pressure (auto-PEEP). We therefore studied the impact of adult sized DLTs on the dynamic auto-PEEP during OLV. In this prospective clinical study, dynamic auto-PEEP was determined in 72 patients undergoing thoracic surgery, with right- and left-sided DLTs of various sizes. During OLV, air trapping was provoked by increasing inspiration to expiration ratio from 1:2 to 2:1 (five steps). Based on measured flow rate, airway pressure (Paw) and bronchial pressure (Pbronch), the pressure gradient across the DLT (ΔPDLT) and the total auto-PEEP in the respiratory system (i.e. the lungs, the DLT and the ventilator circuit) were determined. Subsequently the DLT's share in total auto-PEEP was calculated. ΔPDLT was 2.3 (0.7) cm H2O over the entire breathing cycle. At the shortest expiratory time the mean total auto-PEEP was 2.9 (1.5) cm H2O (range 0-5.9 cm H2O). The DLT caused 27 to 31% of the total auto-PEEP. Size and side of the DLT's bronchial limb did not impact auto-PEEP significantly. Although the DLT contributes to the overall auto-PEEP, its contribution is small and independent of size and side of the DLT's bronchial limb. The choice of DLT does not influence the risk of auto-PEEP during OLV to a clinically relevant extent. DRKS00005648. © 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.

  12. Respiratory mechanics in COPD patients who failed non-invasive ventilation: role of intrinsic PEEP.

    PubMed

    Antonaglia, Vittorio; Ferluga, Massimo; Capitanio, Guido; Lucangelo, Umberto; Piller, Fulvia; Roman-Pognuz, Erik; Biancardi, Bruno; Caggegi, Giuseppe Davide; Zin, Walter A

    2012-10-15

    Non-invasive positive pressure ventilation (NPPV) is the first choice to treat exacerbations in COPD patients. NPPV can fail owing to different causes related to gas exchange impairment (RF group) or intolerance (INT group). To assess if the respiratory mechanical properties and the ratio between the dynamic and static intrinsic positive end-expiratory pressure (PEEP(i),dyn/PEEP(i),stat), reflecting lung mechanical inequalities, were different between groups, 29 COPD patients who failed NPPV (15 RF and 14 INT) were studied, early after the application of invasive ventilation. Blood gas analysis, clinical status, and mechanical properties were measured. pH was higher in INT patients before intubation (p<0.001). PEEP(i),dyn/PEEP(i),stat was found higher in INT group with (p=0.021) and without PEEP (ZEEP, p<0.01). PEEP(i),dyn/PEEP(i),stat was exponentially associated with the duration of NPPV in INT group (p=0.011). INT and RF patients had similar impairment of respiratory system resistance and elastance.

  13. Auto-PEEP in the multisystem injured patient: an elusive complication.

    PubMed

    Moore, F A; Haenel, J B; Moore, E E; Abernathy, C M

    1990-11-01

    Auto-PEEP (A-PEEP), unrecognized alveolar positive and expiratory pressure during mechanical ventilation, is an acknowledged hazard in patients with chronic obstructive lung disease. We evaluated 50 consecutive trauma patients for the presence of A-PEEP and its effect on hemodynamic stability. Injury Severity Scores (ISS) were 8 to 41 (21 +/- 1); Revised Trauma Scores (RTS) ranged from 2.0 to 7.8 (6.2 +/- 0.2). Mode of ventilation was assist control, inspiratory flow rates were 40 to 120 L/M (78 +/- 2). A-PEEP, determined in the non-assisting patient by occluding the expiratory port at end exhalation, was present in 28 patients (56%) and ranged from 1 to 12 cm H2O (5.3 +/- 0.4 cm H2O). Data segregated by A-PEEP versus no A-PEEP were as follows (Mean +/- SEM): [table: see text] *P less than 0.05, VE = minute ventilation, Paw = mean airway pressure. Upon reversal of A-PEEP in the eight patients with levels greater than 5 cm H2O, mean blood pressure rose from 90 +/- 17 to 102 +/- 22 mm Hg and central venous pressure fell from 13 +/- 5 to 7 +/- 5 mm Hg. A-PEEP was successfully treated in these eight patients by increasing peak flows, minimizing VE requirements and selective use of bronchodilators. In sum, the hypermetabolic ventilated trauma patient should be monitored routinely for this common phenomenon which may have profound cardiopulmonary effects in the setting of acute resuscitation.

  14. Should PEEP Titration Be Based on Chest Mechanics in Patients With ARDS?

    PubMed

    Kallet, Richard H

    2016-06-01

    Functional residual capacity (FRC) is essentially the alveolar volume and a determinant of both oxygenation and respiratory system compliance (CRS). ARDS decreases FRC, and sufficient PEEP restores FRC; thus, assessments of PEEP by its impact on oxygenation and CRS are intimately linked. PEEP also can ameliorate or aggravate ventilator-induced lung injury. Therefore, it can be argued that PEEP should be titrated primarily by its impact on CRS The pro position argues that the heterogeneous nature of lung injury and its unique presentation in individual patients results in an uncoupling between oxygenation and CRS Therefore, relying upon oxygenation alone may enhance lung injury and mortality risk, particularly in those with severe ARDS. The con argument is that the preponderance of preclinical and clinical evidence suggests that a relatively narrow range of PEEP is required to manage all but the most severe cases of ARDS. In addition, pathological alterations in chest wall compliance confuse the interpretation of chest mechanics. Moreover, ambiguities and technical limitations in advanced techniques, such as esophageal manometry and pressure-volume curves, add a layer of complexity that renders its broader application in all ARDS patients both impractical and unnecessary. Whether sophisticated monitoring of chest mechanics in severe ARDS might improve outcomes further is open to question and should be studied further. However, it is highly improbable that we will ever discover a PEEP strategy that optimizes all aspects of cardiorespiratory function and chest mechanics for individual patients suffering from ARDS. Copyright © 2016 by Daedalus Enterprises.

  15. Moderate Peep After Tracheal Lipopolysaccharide Instillation Prevents Inflammation and Modifies the Pattern of Brain Neuronal Activation

    PubMed Central

    Quilez, María Elisa; Rodríguez-González, Raquel; Turon, Marc; Fernandez-Gonzalo, Sol; Villar, Jesús; Kacmarek, Robert M.; Gómez, Ma Nieves; Oliva, Joan Carles; Blanch, Lluís; López-Aguilar, Josefina

    2015-01-01

    ABSTRACT Background: Ventilatory strategy and specifically positive end-expiratory pressure (PEEP) can modulate the inflammatory response and pulmonary-to-systemic translocation of lipopolysaccharide (LPS). Both inflammation and ventilatory pattern may modify brain activation, possibly worsening the patient's outcome and resulting in cognitive sequelae. Methods: We prospectively studied Sprague–Dawley rats randomly assigned to undergo 3 h mechanical ventilation with 7 mL/kg tidal ventilation and either 2 cmH2O or 7 cmH2O PEEP after intratracheal instillation of LPS or saline. Healthy nonventilated rats served as baseline. We analyzed lung mechanics, gas exchange, lung and plasma cytokine levels, lung apoptotic cells, and lung neutrophil infiltration. To evaluate brain neuronal activation, we counted c-Fos immunopositive cells in the retrosplenial cortex (RS), thalamus, supraoptic nucleus (SON), nucleus of the solitary tract (NTS), paraventricular nucleus (PVN), and central amygdala (CeA). Results: LPS increased lung neutrophilic infiltration, lung and systemic MCP-1 levels, and neuronal activation in the CeA and NTS. LPS-instilled rats receiving 7 cmH2O PEEP had less lung and systemic inflammation and more c-Fos-immunopositive cells in the RS, SON, and thalamus than those receiving 2 cmH2O PEEP. Applying 7 cmH2O PEEP increased neuronal activation in the CeA and NTS in saline-instilled rats, but not in LPS-instilled rats. Conclusions: Moderate PEEP prevented lung and systemic inflammation secondary to intratracheal LPS instillation. PEEP also modified the neuronal activation pattern in the RS, SON, and thalamus. The relevance of these differential brain c-Fos expression patterns in neurocognitive outcomes should be explored. PMID:26398809

  16. Speech effects of a speaking valve versus external PEEP in tracheostomized ventilator-dependent neuromuscular patients.

    PubMed

    Prigent, Hélène; Garguilo, Marine; Pascal, Sophie; Pouplin, Samuel; Bouteille, Justine; Lejaille, Michèle; Orlikowski, David; Lofaso, Frédéric

    2010-10-01

    Many patients with respiratory failure related to neuromuscular disease receive chronic invasive ventilation through a tracheostomy. Improving quality of life, of which speech is an important component, is a major goal in these patients. We compared the effects on breathing and speech of low-level positive end-expiratory pressure (PEEP, 5 cmH(2)O) and of a Passy-Muir speaking valve (PMV) during assist-control ventilation. We studied ten patients with neuromuscular disorders, between December 2008 and April 2009. Flow was measured using a pneumotachograph. Microphone speech recordings were subjected to both quantitative measurements and qualitative assessments; the latter consisted of both an intelligibility score (using a French adaptation of the Frenchay Dysarthria Assessment) and a perceptual score determined by two speech therapists. Text reading time, perceptive score, intelligibility score, speech comfort, and respiratory comfort were similar with PEEP and PMV. During speech with 5 cmH(2)O PEEP, six of the ten patients had no return of expiratory gas to the expiratory line and, therefore, had the entire insufflated volume available for speech, a condition met during PMV use in all patients. During speech, the respiratory rate increased by at least 3 cycles/min above the backup rate in seven patients with PEEP and in none of the patients with PMV. Low-level PEEP is as effective as PMV in ensuring good speech quality, which might be explained by sealed expiratory line with low-level PEEP and/or respiratory rate increase during speech with PEEP observed in most of the patients.

  17. 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.

  18. Increase in cardiac output and PEEP as mechanism of pulmonary optimization.

    PubMed

    Curiel, C; Martínez, R; Pinto, V; Rosales, A; D'Empaire, G; Sánchez De Leon, R

    1995-03-01

    The influence of cardiac output (CO) and PEEP on pulmonary shunt (Qs/Qt) has been the subjects of considerable investigation but findings are controversial. The role of CO and PEEP on 19 isolated rabbit lung preparations perfused with hypoxic mixture (6% CO2, 10% O2, and 84% N2), which resulted in a constant oxygen venous pressure (64 +/- 5.6 mmHg) has been studied. The first group of 11 preparations were used to study the influence of CO modifications with room air ventilation on the Qs/Qt when the CO rises in 48%; in the second group simultaneous modifications in CO and PEEP (0.5 and 10 cm H2O) were performed. A positive correlation (p < 0.01) in Qs/Qt (0.048 +/- 0.04 to 0.12933 +/- 0.09) was found when the CO increased in the first experimental group, the fluid filtration rate (FFR) also increased and the pulmonary vascular resistance (PVR) remained stable. In the second group an increase of 5 and 10 cm H2O of PEEP at constant CO reduced the Qs/Qt (0.0361 +/- 0.02 to 0.0184 +/- 0.006) while it increased the arterio-venous oxygen difference, PVR and FFR. During high CO conditions increase of 5 and 10 cm H2O of PEEP reduced the Qs/Qt (0.099 +/- 0.03 to 0.027 +/- 0.02) and FFR. These data suggest that when the Qs/Qt is increased, the use of PEEP can compensate the ventilation/perfusion alterations and restore pulmonary gas exchange.

  19. Positive end-expiratory pressure (PEEP) during anaesthesia for prevention of mortality and postoperative pulmonary complications.

    PubMed

    Barbosa, Fabiano T; Castro, Aldemar A; de Sousa-Rodrigues, Célio F

    2014-06-12

    General anaesthesia causes atelectasis, which can lead to impaired respiratory function. Positive end-expiratory pressure (PEEP) is a mechanical manoeuvre that increases functional residual capacity (FRC) and prevents collapse of the airways, thereby reducing atelectasis. It is not known whether intraoperative PEEP alters the risks of postoperative mortality and pulmonary complications. This review was originally published in 2010 and was updated in 2013. To assess the benefits and harms of intraoperative PEEP in terms of postoperative mortality and pulmonary outcomes in all adult surgical patients. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 10, part of The Cochrane Library, as well as MEDLINE (via Ovid) (1966 to October 2013), EMBASE (via Ovid) (1980 to October 2013), CINAHL (via EBSCOhost) (1982 to October 2013), ISI Web of Science (1945 to October 2013) and LILACS (via BIREME interface) (1982 to October 2010). The original search was performed in January 2010. We included randomized clinical trials assessing the effects of PEEP versus no PEEP during general anaesthesia on postoperative mortality and postoperative respiratory complications in adults, 16 years of age and older. Two review authors independently selected papers, assessed trial quality and extracted data. We contacted study authors to ask for additional information, when necessary. We calculated the number of additional participants needed (information size) to make reliable conclusions. This updated review includes two new randomized trials. In total, 10 randomized trials with 432 participants and four comparisons are included in this review. One trial had a low risk of bias. No differences were demonstrated in mortality, with risk ratio (RR) of 0.97 (95% confidence interval (CI) 0.20 to 4.59; P value 0.97; 268 participants, six trials, very low quality of evidence (grading of recommendations assessment, development and evaluation (GRADE)), and in pneumonia

  20. PEEP decreases atelectasis and extravascular lung water but not lung tissue volume in surfactant-washout lung injury.

    PubMed

    Luecke, Thomas; Roth, Harry; Herrmann, Peter; Joachim, Alf; Weisser, Gerald; Pelosi, Paolo; Quintel, Michael

    2003-11-01

    To examine the effects of positive end-expiratory pressure (PEEP) on extravascular lung water (EVLW), lung tissue, and lung volume. Experimental animal study at a university research facility. Fifteen adult sheep. All animals were studied before and after saline washout-induced lung injury while ventilated with sequentially increasing PEEP (0, 7, 14, or 21 cmH(2)O). Lung volume was determined by computed tomography and EVLW by the thermal dye dilution technique. Saline washout significantly increased lung tissue volume (21+/-3 to 37+/-5 ml/kg) and EVLW (9+/-2 to 36+/-9 ml/kg). While increasing levels of PEEP reduced EVLW (30+/-7, 24+/-8, and 18+/-4 ml/kg), lung tissue volume remained constant. Total lung volume significantly increased (50+/-8 ml/kg at PEEP 0 to 77+/-12 ml/kg at PEEP 21). Nonaerated lung volume significantly decreased and was closely correlated with the changes in EVLW ( r=0.67). In addition, a highly significant correlation was found between PEEP-induced decrease in nonaerated lung volume and decrease in transpulmonary shunt ( r=0.83). The main findings are as follows: (a) PEEP effectively decreases EVLW. (b) The decrease in EVLW is closely correlated with the PEEP-induced decrease in nonaerated lung volume, making EVLW a valuable bedside parameter indicating alveolar recruitment, similar to measurements of transpulmonary shunt. (c) As excess tissue volume remained constant, however, EVLW may not be suitable to reflect overall severity of lung disease

  1. PEEP-ZEEP technique: cardiorespiratory repercussions in mechanically ventilated patients submitted to a coronary artery bypass graft surgery.

    PubMed

    Herbst-Rodrigues, Marcus Vinicius; Carvalho, Vitor Oliveira; Auler, José Otávio Costa; Feltrim, Maria Ignez Zanetti

    2011-09-13

    The PEEP-ZEEP technique is previously described as a lung inflation through a positive pressure enhancement at the end of expiration (PEEP), followed by rapid lung deflation with an abrupt reduction in the PEEP to 0 cmH2O (ZEEP), associated to a manual bilateral thoracic compression. To analyze PEEP-ZEEP technique's repercussions on the cardio-respiratory system in immediate postoperative artery graft bypass patients. 15 patients submitted to a coronary artery bypass graft surgery (CABG) were enrolled prospectively, before, 10 minutes and 30 minutes after the technique. Patients were curarized, intubated, and mechanically ventilated. To perform PEEP-ZEEP technique, saline solution was instilled into their orotracheal tube than the patient was reconnected to the ventilator. Afterwards, the PEEP was increased to 15 cmH2O throughout 5 ventilatory cycles and than the PEEP was rapidly reduced to 0 cmH2O along with manual bilateral thoracic compression. At the end of the procedure, tracheal suction was accomplished. The inspiratory peak and plateau pressures increased during the procedure (p < 0.001) compared with other pressures during the assessment periods; however, they were within lung safe limits. The expiratory flow before the procedure were 33 ± 7.87 L/min, increasing significantly during the procedure to 60 ± 6.54 L/min (p < 0.001), diminishing to 35 ± 8.17 L/min at 10 minutes and to 36 ± 8.48 L/min at 30 minutes. Hemodynamic and oxygenation variables were not altered. The PEEP-ZEEP technique seems to be safe, without alterations on hemodynamic variables, produces elevated expiratory flow and seems to be an alternative technique for the removal of bronchial secretions in patients submitted to a CABG.

  2. PEEP-ZEEP technique: cardiorespiratory repercussions in mechanically ventilated patients submitted to a coronary artery bypass graft surgery

    PubMed Central

    2011-01-01

    Background The PEEP-ZEEP technique is previously described as a lung inflation through a positive pressure enhancement at the end of expiration (PEEP), followed by rapid lung deflation with an abrupt reduction in the PEEP to 0 cmH2O (ZEEP), associated to a manual bilateral thoracic compression. Aim To analyze PEEP-ZEEP technique's repercussions on the cardio-respiratory system in immediate postoperative artery graft bypass patients. Methods 15 patients submitted to a coronary artery bypass graft surgery (CABG) were enrolled prospectively, before, 10 minutes and 30 minutes after the technique. Patients were curarized, intubated, and mechanically ventilated. To perform PEEP-ZEEP technique, saline solution was instilled into their orotracheal tube than the patient was reconnected to the ventilator. Afterwards, the PEEP was increased to 15 cmH2O throughout 5 ventilatory cycles and than the PEEP was rapidly reduced to 0 cmH2O along with manual bilateral thoracic compression. At the end of the procedure, tracheal suction was accomplished. Results The inspiratory peak and plateau pressures increased during the procedure (p < 0.001) compared with other pressures during the assessment periods; however, they were within lung safe limits. The expiratory flow before the procedure were 33 ± 7.87 L/min, increasing significantly during the procedure to 60 ± 6.54 L/min (p < 0.001), diminishing to 35 ± 8.17 L/min at 10 minutes and to 36 ± 8.48 L/min at 30 minutes. Hemodynamic and oxygenation variables were not altered. Conclusion The PEEP-ZEEP technique seems to be safe, without alterations on hemodynamic variables, produces elevated expiratory flow and seems to be an alternative technique for the removal of bronchial secretions in patients submitted to a CABG. PMID:21914178

  3. State of the evidence: mechanical ventilation with PEEP in patients with cardiogenic shock.

    PubMed

    Wiesen, Jonathan; Ornstein, Moshe; Tonelli, Adriano R; Menon, Venu; Ashton, Rendell W

    2013-12-01

    The need to provide invasive mechanical ventilatory support to patients with myocardial infarction and acute left heart failure is common. Despite the large number of patients requiring mechanical ventilation in this setting, there are remarkably few data addressing the ideal mode of respiratory support in such patients. Although there is near universal acceptance regarding the use of non-invasive positive pressure ventilation in patients with acute pulmonary oedema, there is more concern with invasive positive pressure ventilation owing to its more significant haemodynamic impact. Positive end-expiratory pressure (PEEP) is almost universally applied in mechanically ventilated patients due to benefits in gas exchange, recruitment of alveolar units, counterbalance of hydrostatic forces leading to pulmonary oedema and maintenance of airway patency. The limited available clinical data suggest that a moderate level of PEEP is safe to use in severe left ventricular (LV) dysfunction and cardiogenic shock, and may provide haemodynamic benefits as well in LV failure which exhibits afterload-sensitive physiology.

  4. Electrical Impedance Tomography-guided PEEP Titration in Patients Undergoing Laparoscopic Abdominal Surgery.

    PubMed

    He, Xingying; Jiang, Jingjing; Liu, Yuli; Xu, Haitao; Zhou, Shuangqiong; Yang, Shibo; Shi, Xueyin; Yuan, Hongbin

    2016-04-01

    The aim of the study is to utilize electrical impedance tomography (EIT) to guide positive end-expiratory pressure (PEEP) and to optimize oxygenation in patients undergoing laparoscopic abdominal surgery.Fifty patients were randomly assigned to the control (C) group and the EIT (E) group (n = 25 each). We set the fraction of inspired oxygen (FiO2) at 0.30. The PEEP was titrated and increased in a 2-cm H2O stepwise manner, from 6 to 14 cm H2O. Hemodynamic variables, respiratory mechanics, EIT images, analysis of blood gas, and regional cerebral oxygen saturation were recorded. The postoperative pulmonary complications within the first 5 days were also observed.We chose 10 cm H2O and 8 cm H2O as the "ideal" PEEP for the C and the E groups, respectively. EIT-guided PEEP titration led to a more dorsal shift of ventilation. The PaO2/FiO2 ratio in the E group was superior to that in the C group in the pneumoperitoneum period, though the difference was not significant (330 ± 10 vs 305.56 ± 4 mm Hg; P = 0.09). The C group patients experienced 8.7% postoperative pulmonary complications versus 5.3% among the E group patients (relative risk 1.27, 95% confidence interval 0.31-5.3, P = 0.75).Electrical impedance tomography represents a new promising technique that could enable anesthesiologists to assess regional ventilation of the lungs and optimize global oxygenation for patients undergoing laparoscopic abdominal surgery.

  5. Contribution of lung stretch depressor reflex to nonlinear fall in cardiac output during PEEP.

    PubMed

    Schreuder, J J; Jansen, J R; Versprille, A

    1984-06-01

    The hypothesis that lung stretch reflexes elicit negative cardiovascular effects during positive end-expiratory pressure (PEEP) application in a ramp procedure up to 15 cmH2O was tested in piglets under steady-state anesthesia and muscle relaxation. The effects of lung stretch on hemodynamics were studied by comparing the differences in responses during PEEP application with two different tidal volumes. In both ventilatory conditions cardiac output and aortic pressure decreased nonlinearly in three phases with the rise of PEEP: a gradual decrease in phase I, a sharp decrease in phase II, and again a more gradual decrease in phase III. Heart rate decreased significantly in phase II. In the series with the larger tidal volume, implying more lung stretch during insufflation, phase II was between a PEEP of 2.6 and 9 cmH2O. In the series with the smaller tidal volume, phase II occurred between 5.7 and 10.5 cmH2O. To assess the contribution of lung stretch reflexes to the decrease in cardiac output we also related cardiac output to the changes in central venous pressure. Again a nonlinear response was observed, indicating that an additional effect besides the rise in mean central venous pressure was involved in the decrease in cardiac output. During ventilation with the smaller tidal volume, phase II of the decrease in cardiac output was also shifted to higher values of mean central venous pressure, which only could be ascribed to the differences in lung stretch at insufflation. It appeared that under circumstances of artificial ventilation the onset of the reflex is determined by a characteristic threshold of lung stretch.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Electrical Impedance Tomography-guided PEEP Titration in Patients Undergoing Laparoscopic Abdominal Surgery

    PubMed Central

    He, Xingying; Jiang, Jingjing; Liu, Yuli; Xu, Haitao; Zhou, Shuangqiong; Yang, Shibo; Shi, Xueyin; Yuan, Hongbin

    2016-01-01

    Abstract The aim of the study is to utilize electrical impedance tomography (EIT) to guide positive end-expiratory pressure (PEEP) and to optimize oxygenation in patients undergoing laparoscopic abdominal surgery. Fifty patients were randomly assigned to the control (C) group and the EIT (E) group (n = 25 each). We set the fraction of inspired oxygen (FiO2) at 0.30. The PEEP was titrated and increased in a 2-cm H2O stepwise manner, from 6 to 14 cm H2O. Hemodynamic variables, respiratory mechanics, EIT images, analysis of blood gas, and regional cerebral oxygen saturation were recorded. The postoperative pulmonary complications within the first 5 days were also observed. We chose 10 cm H2O and 8 cm H2O as the “ideal” PEEP for the C and the E groups, respectively. EIT-guided PEEP titration led to a more dorsal shift of ventilation. The PaO2/FiO2 ratio in the E group was superior to that in the C group in the pneumoperitoneum period, though the difference was not significant (330 ± 10 vs 305.56 ± 4 mm Hg; P = 0.09). The C group patients experienced 8.7% postoperative pulmonary complications versus 5.3% among the E group patients (relative risk 1.27, 95% confidence interval 0.31–5.3, P = 0.75). Electrical impedance tomography represents a new promising technique that could enable anesthesiologists to assess regional ventilation of the lungs and optimize global oxygenation for patients undergoing laparoscopic abdominal surgery. PMID:27057904

  7. Haemodynamic effects of pressure support and PEEP ventilation by nasal route in patients with stable chronic obstructive pulmonary disease.

    PubMed Central

    Ambrosino, N; Nava, S; Torbicki, A; Riccardi, G; Fracchia, C; Opasich, C; Rampulla, C

    1993-01-01

    BACKGROUND--Intermittent positive pressure ventilation applied through a nasal mask has been shown to be useful in the treatment of chronic respiratory insufficiency. Pressure support ventilation is an assisted mode of ventilation which is being increasingly used. Invasive ventilation with intermittent positive pressure, with or without positive end expiratory pressure (PEEP), has been found to affect venous return and cardiac output. This study evaluated the acute haemodynamic support ventilation by nasal mask, with and without the application of PEEP, in patients with severe stable chronic obstructive pulmonary disease and hypercapnia. METHODS--Nine patients with severe stable chronic obstructive pulmonary disease performed sessions lasting 10 minutes each of pressure support ventilation by nasal mask while undergoing right heart catheterisation for clinical evaluation. In random order, four sessions of nasal pressure support ventilation were applied consisting of: (1) peak inspiratory pressure (PIP) 10 cm H2O, PEEP 0 cm H2O; (2) PIP 10 cm H2O, PEEP 5 cm H2O; (3) PIP 20 cm H2O, PEEP 0 cm H2O; (4) PIP 20 cm H2O, PEEP 5 cm H2O. RESULTS--Significant increases in arterial oxygen tension (Pao2) and saturation (Sao2) and significant reductions in arterial carbon dioxide tension (PaCO2) and changes in pH were observed with a PIP of 20 cm H2O. Statistical analysis showed that the addition of 5 cm H2O PEEP did not further improve arterial blood gas tensions. Comparison of baseline values with measurements performed after 10 minutes of each session of ventilation showed that all modes of ventilation except PIP 10 cm H2O without PEEP induced a small but significant increase in pulmonary capillary wedge pressure. In comparison with baseline values, a significant decrease in cardiac output and oxygen delivery was induced only by the addition of PEEP to both levels of PIP. CONCLUSIONS--In patients with severe stable chronic obstructive pulmonary disease and hypercapnia

  8. Marked differences between prone and supine sheep in effect of PEEP on perfusion distribution in zone II lung.

    PubMed

    Walther, Sten M; Johansson, Mats J; Flatebø, Torun; Nicolaysen, Anne; Nicolaysen, Gunnar

    2005-09-01

    The classic four-zone model of lung blood flow distribution has been questioned. We asked whether the effect of positive end-expiratory pressure (PEEP) is different between the prone and supine position for lung tissue in the same zonal condition. Anesthetized and mechanically ventilated prone (n = 6) and supine (n = 5) sheep were studied at 0, 10, and 20 cm H2O PEEP. Perfusion was measured with intravenous infusion of radiolabeled 15-microm microspheres. The right lung was dried at total lung capacity and diced into pieces (approximately 1.5 cm3), keeping track of the spatial location of each piece. Radioactivity per unit weight was determined and normalized to the mean value for each condition and animal. In the supine posture, perfusion to nondependent lung regions decreased with little relative perfusion in nondependent horizontal lung planes at 10 and 20 cm H2O PEEP. In the prone position, the effect of PEEP was markedly different with substantial perfusion remaining in nondependent lung regions and even increasing in these regions with 20 cm H2O PEEP. Vertical blood flow gradients in zone II lung were large in supine, but surprisingly absent in prone, animals. Isogravitational perfusion heterogeneity was smaller in prone than in supine animals at all PEEP levels. Redistribution of pulmonary perfusion by PEEP ventilation in supine was largely as predicted by the zonal model in marked contrast to the findings in prone. The differences between postures in blood flow distribution within zone II strongly indicate that factors in addition to pulmonary arterial, venous, and alveolar pressure play important roles in determining perfusion distribution in the in situ lung. We suggest that regional variation in lung volume through the effect on vascular resistance is one such factor and that chest wall conformation and thoracic contents determine regional lung volume.

  9. Positive end-expiratory pressure (PEEP) during anaesthesia for the prevention of mortality and postoperative pulmonary complications.

    PubMed

    Imberger, Georgina; McIlroy, David; Pace, Nathan Leon; Wetterslev, Jørn; Brok, Jesper; Møller, Ann Merete

    2010-09-08

    General anaesthesia causes atelectasis which can lead to impaired respiratory function. Positive end-expiratory pressure (PEEP) is a mechanical manoeuvre which increases functional residual capacity (FRC) and prevents collapse of the airways thereby reducing atelectasis. It is not known whether intra-operative PEEP alters the risk of postoperative mortality and pulmonary complications. To assess the benefits and harms of intraoperative PEEP, for all adult surgical patients, on postoperative mortality and pulmonary outcomes. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, Issue 4), MEDLINE (via Ovid) (1966 to January 2010), EMBASE (via Ovid) (1980 to January 2010), CINAHL (via EBSCOhost) (1982 to January 2010), ISI Web of Science (1945 to January 2010) and LILACS (via BIREME interface) (1982 to January 2010). We included randomized clinical trials that evaluated the effect of PEEP versus no PEEP, during general anaesthesia, on postoperative mortality and postoperative respiratory complications. We included studies irrespective of language and publication status. Two investigators independently selected papers, extracted data that fulfilled our outcome criteria and assessed the quality of all included trials. We undertook pooled analyses, where appropriate. For our primary outcome (mortality) and two secondary outcomes (respiratory failure and pneumonia), we calculated the number of further patients needed (information size) in order to make reliable conclusions. We included eight randomized trials with a total of 330 patients. Two trials had a low risk of bias. There was no difference demonstrated for mortality (relative risk (RR) 0.95, 95% CI 0.14 to 6.39). Two statistically significant results were found: the PEEP group had a higher PaO(2)/FiO(2) on day 1 postoperatively (mean difference (MD) 22.98, 95% CI 4.40 to 41.55) and postoperative atelectasis (defined as an area of collapsed lung, quantified by

  10. [Relationship between the alveolar-arterial oxygen gradient and PaO₂/FiO₂-introducing PEEP into the model].

    PubMed

    Sánchez Casado, M; Quintana Díaz, M; Palacios, D; Hortigüela, V; Marco Schulke, C; García, J; Canabal, A; Pérez Pedrero, M J; Velasco Ramos, A; Arrese, M A

    2012-01-01

    To determine whether the alveolar-arterial oxygen gradient (Grad[A-a]O₂) helps confirm the influence of PEEP on PaFi (PaO₂/FiO₂). Observational study; we used linear regression to perform a multivariate study to improve the PaFi formula by taking PEEP into account. Tertiary hospital. We included all patients who were admitted to the intensive care unit, regardless of pulmonary damage. We recorded personal history, clinical judgment, intensive care data, severity scores on the first day and progression. Two calculated variables: PaFi and Grad(A-a)O₂. A total of 956 patients were included: 63.9% men; median age 68 years. On the first day, 31.8% did not have mechanical ventilation (MV), 13.1% had non-invasive MV and 55.1% had invasive MV. PaFi values: 32.9% 0-200, 32.2% 201-300, and 34.8% >300. PEEP values: 0-5 69.8%, 6-10 27.5% and >10 2.6%. We observed a correlation (Pearson) between Grad(A-a)O₂ and PaFi of -0.84 (p<0.001). On performing multiple regression (dependent variable: Grad[A-a]O₂), the following variables were included in the model: PaFi, PEEP, APACHE IV and SOFA; coefficient of determination (R²) of 0.62 without PEEP and 0.72 with PEEP. We changed the PaFi formula, referring to it as PaFip (PaFi plus PEEP): Ln (PaFi/[PEEP+12]). Correlation index between PaFip and Grad(A-a)O₂: -0.9 (p<0.001). We performed linear regression (dependent variable: Grad[A-a]O₂) and used PaFip instead of PaFi. Only PaFi remained in the model, and was discretely complemented by APACHE IV; R²=0.8. By adding PEEP to the PaFi model (PaFip), we clearly improve the latter, as reflected by a better goodness of fit. Copyright © 2011 Elsevier España, S.L. and SEMICYUC. All rights reserved.

  11. Reliability of Single-Use PEEP-Valves Attached to Self-Inflating Bags during Manual Ventilation of Neonates – An In Vitro Study

    PubMed Central

    Hartung, Julia C.; Wilitzki, Silke; Thio-Lluch, Marta; te Pas, Arjan B.; Schmalisch, Gerd; Roehr, Charles C.

    2016-01-01

    Introduction International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP. Methods Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20cmH2O, VR 60/min, flow 8L/min. PEEP settings of 5 and 10cmH2O were studied. A second test was conducted with settings of PIP 40cmH2O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO2SMO+). Results Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25th and 75th percentile) delivered PEEP with standard settings was 3.4(2.7–3.8)cmH2O when set to 5cmH2O and 6.1(4.9–7.1)cmH2O when set to 10cmH2O. Increasing the PIP from 20 to 40 cmH2O led to a median (25th and 75th percentile) decrease in PEEP to 2.3(1.8–2.7)cmH2O and 4.3(3.2–4.8)cmH2O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1–3.3)cmH2O and 5.0(3.5–6.2)cmH2O for both PEEP settings. Conclusion Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates. PMID:26914209

  12. Reliability of Single-Use PEEP-Valves Attached to Self-Inflating Bags during Manual Ventilation of Neonates--An In Vitro Study.

    PubMed

    Hartung, Julia C; Wilitzki, Silke; Thio-Lluch, Marta; te Pas, Arjan B; Schmalisch, Gerd; Roehr, Charles C

    2016-01-01

    International resuscitation guidelines suggest to use positive end-expiratory pressure (PEEP) during manual ventilation of neonates. Aim of our study was to test the reliability of self-inflating bags (SIB) with single-use PEEP valves regarding PEEP delivery and the effect of different peak inflation pressures (PIP) and ventilation rates (VR) on the delivered PEEP. Ten new single-use PEEP valves from 5 manufacturers were tested by ventilating an intubated 1 kg neonatal manikin containing a lung model with a SIB that was actuated by an electromechanical plunger device. Standard settings: PIP 20 cmH2O, VR 60/min, flow 8 L/min. PEEP settings of 5 and 10 cmH2O were studied. A second test was conducted with settings of PIP 40 cmH2O and VR 40/min. The delivered PEEP was measured by a respiratory function monitor (CO2SMO+). Valves from one manufacturer delivered no relevant PEEP and were excluded. The remaining valves showed a continuous decay of the delivered pressure during expiration. The median (25th and 75th percentile) delivered PEEP with standard settings was 3.4(2.7-3.8) cmH2O when set to 5 cmH2O and 6.1(4.9-7.1) cmH2O when set to 10 cmH2O. Increasing the PIP from 20 to 40 cmH2O led to a median (25th and 75th percentile) decrease in PEEP to 2.3(1.8-2.7) cmH2O and 4.3(3.2-4.8) cmH2O; changing VR from 60 to 40/min led to a PEEP decrease to 2.8(2.1-3.3) cmH2O and 5.0(3.5-6.2) cmH2O for both PEEP settings. Single-use PEEP valves do not reliably deliver the set PEEP. PIP and VR have an effect on the delivered PEEP. Operators should be aware of these limitations when manually ventilating neonates.

  13. Low tidal volume, high respiratory rate and auto-PEEP: the importance of the basics

    PubMed Central

    Patroniti, Nicolò; Pesenti, Antonio

    2003-01-01

    Recent studies have shown that application of the ARDSNet low tidal volume strategy (i.e. allowing an increase in respiratory rate in order to minimize hypercapnia in those with low tidal volume) may generate consistent auto-PEEP (positive end-expiratory pressure), and this is not efficient in improving clearance of carbon dioxide. The present commentary deals with some of the recent controversies related to use of a low tidal volume strategy, as implemented in the ARDSNet trial, which has proved successful in reducing mortality rates in patients with acute respiratory distress syndrome. We emphasize the importance of basic physiological knowledge and sound respiratory monitoring. PMID:12720551

  14. Partial liquid ventilation shows dose-dependent increase in oxygenation with PEEP and decreases lung injury associated with mechanical ventilation.

    PubMed

    Suh, G Y; Chung, M P; Park, S J; Koh, Y; Kang, K W; Kim, H; Han, J; Rhee, C H; Kwon, O J

    2000-09-01

    The purpose of this article is to evaluate the effect of positive end-expiratory pressure (PEEP) during partial liquid ventilation (PLV) and to investigate if lung damage associated with mechanical ventilation can be reduced by PLV. Twenty-two New-Zealand white rabbits were ventilated in pressure-controlled mode maintaining constant tidal volume (10 mL/kg). Lung injury was induced by repeated saline lavage (PaO2 < 100 mm Hg). Two incremental PEEP steps maneuvers (IPSMs) from 2 to 10 cm H2O in 2 cm H2O steps were performed sequentially. The control group received the first IPSM in the supine position and were turned prone for the second IPSM. In the PLV group (n = 7), 12 mL/kg of perfluorodecalin was instilled after lung injury before the two IPSMs. The early prone group (n = 7) received both IPSMs in the prone position. Parameters of gas exchange, lung mechanics, and hemodynamics as well as pathology were examined. During the first IPSM, the PLV group showed a significant increase in PaO2 after instillation of perfluorodecalin (P < .05) and then showed a dose-dependent increase in PaO2 with PEER. The control and EP groups showed improvement in PaO2 only at higher PEEP, eventually showing no intergroup differences at PEEP of 10 cm H2O. During the second IPSM only the PLV group retained its ability to increase PaO2 to the level obtained during the first IPSM (P < .05 compared with control and EP groups). During the first IPSM all three groups showed increasing trend in static compliance (Cst) with PEEP peaking at PEEP of 8 cm H2O. During the second IPSM, only the PLV group showed increase in static compliance with PEEP (P < .05 compared with other groups). Lung histology revealed significantly less hyaline membrane formation in the PLV group (P < .05). PLV shows dose-dependent increase in oxygenation with PEEP and may reduce lung damage associated with mechanical ventilation.

  15. Pulmonary atelectasis during paediatric anaesthesia: CT scan evaluation and effect of positive endexpiratory pressure (PEEP).

    PubMed

    Serafini, G; Cornara, G; Cavalloro, F; Mori, A; Dore, R; Marraro, G; Braschi, A

    1999-01-01

    The case series consisted of ten children, ranged in age from one to three years (median 1.8 yrs), and in body weight from 10.2 to 13.5 kg (median 11.7 kg), in ASA class 1 or 2, all without lung disease. Having undergone general anaesthesia for cranial or abdominal CT scans, the patients were studied for pulmonary morphology. The first pulmonary CT scan was taken five min after induction of general inhalational anaesthesia; preoxygenation was avoided and an intraoperative FiO2PEEP of 5 cmH2O, all the observed densities disappeared without impairment of heart rate, blood pressure, haemoglobin saturation and endtidal CO2 (PECO2). We conclude that the appearance in children of atelectasis cannot be explained by a reabsorption of O2 mechanism and by denitrogenation. However, a PEEP of 5 cmH2O is able both to recruit all the available alveolar units, and to induce the disappearance of atelectasis in dependent lung regions.

  16. Quantifying the roles of tidal volume and PEEP in the pathogenesis of ventilator-induced lung injury.

    PubMed

    Seah, Adrian S; Grant, Kara A; Aliyeva, Minara; Allen, Gilman B; Bates, Jason H T

    2011-05-01

    Management of patients with acute lung injury (ALI) rests on achieving a balance between the gas exchanging benefits of mechanical ventilation and the exacerbation of tissue damage in the form of ventilator-induced lung injury (VILI). Optimizing this balance requires an injury cost function relating injury progression to the measurable pressures, flows, and volumes delivered during mechanical ventilation. With this in mind, we mechanically ventilated naive, anesthetized, paralyzed mice for 4 h using either a low or high tidal volume (Vt) with either moderate or zero positive end-expiratory pressure (PEEP). The derecruitability of the lung was assessed every 15 min in terms of the degree of increase in lung elastance occurring over 3 min following a recruitment maneuver. Mice could be safely ventilated for 4 h with either a high Vt or zero PEEP, but when both conditions were applied simultaneously the lung became increasingly unstable, demonstrating worsening injury. We were able to mimic these data using a computational model of dynamic recruitment and derecruitment that simulates the effects of progressively increasing surface tension at the air-liquid interface, suggesting that the VILI in our animal model progressed via a vicious cycle of alveolar leak, degradation of surfactant function, and increasing tissue stress. We thus propose that the task of ventilating the injured lung is usefully understood in terms of the Vt-PEEP plane. Within this plane, non-injurious combinations of Vt and PEEP lie within a "safe region", the boundaries of which shrink as VILI develops.

  17. Evidence on Effective Early Childhood Interventions from the United Kingdom: An Evaluation of the Peers Early Education Partnership (PEEP)

    ERIC Educational Resources Information Center

    Evangelou, Maria; Sylva, Kathy

    2007-01-01

    Efforts to improve the educational achievement of children, especially those from disadvantaged backgrounds, are at the heart of current government policies in the United Kingdom. The Peers Early Education Partnership (PEEP) is an intervention that, since 1995, has worked directly with parents and caregivers of children from infancy to 5 years of…

  18. Effects of unilateral PEEP on biomechanics of both lungs during independent lung ventilation in patients anaesthetised for thoracic surgery.

    PubMed

    Trela-Stachurska, Katarzyna; Nestorowicz, Andrzej; Kotlińska-Hasiec, Edyta; Sawulski, Sławomir; Dąbrowski, Wojciech

    2015-01-01

    Synchronous independent lung ventilation (ILV) is the treatment of choice for unilateral pathology of lung parenchyma. Numerous studies have documented the improved blood oxygenation and clinical efficacy of this procedure. The aim of the present study was to evaluate the effects of ILV on the selected biomechanical parameters of the lungs. The study involved ASA I-II patients undergoing thoracic surgery in the lateral decubitus position under the standard conditions of general anaesthesia with the thoracic cavity closed. ILV with equal separation of the tidal volume was performed with a prototype volume separator, using incremental a PEEP of 0-15 cm H₂O in the dependent lung. Peak pressures, dynamic compliance and airway resistance of both lungs were evaluated. The study included 36 patients. In all of the patients, a PEEP of 5-15 cm H₂O in one lung increased its peak pressures, dynamic compliance and resistances, and variably affected the biomechanical parameters of the other lung. Irrespective of patient positioning on the right or left side, the highest compliance was recorded at a PEEP of 10 cm H₂O. In ILV, peak pressures and airway resistances are higher in the dependent lung compared to compliances in the non-dependent lung. ILV with a PEEP of 5-15 cm H₂O increases the biomechanical parameters of the dependent lung while variably influencing the parameters in the non-dependent lung.

  19. Review: artifical ventilation with positive end-expiratory pressure (PEEP). Historical background, terminology and patho-physiology.

    PubMed

    Stokke, D B

    1976-09-01

    CPPV (continuous positive pressure ventilation) is obviously superior to IPPV (intermittent positive pressure ventilation) for the treatment of patients with acute respiratory insufficiency (ARI) and results within a few minutes in a considerable increase in the oxygen transport. The principle is to add a positive end-expiratory plateau (PEEP) to IPPV, with a subsequent increase in FRC (functional residual capacity) resulting in re-opening in first and foremost the declive alveolae, which can then once again take part in the gas exchange and possibly re-commence the disrupted surfactant production. In this manner the ventilation/perfusion ratio in the diseases lungs is normalized and the intrapulmonary shunting of venous blood (Qs/Qt) will decrease. At the same time the dead space ventilation fraction (VD/VT) normalizes and the compliance of the lungs (CL) increases. The PEEP value, which results in a maximum oxygen transport, and the lowest dead space fraction, also appears to result in the greatest total static compliance (CT) and the greatest increase in mixed venous oxygen tension (PVO2); this value can be termed "optimal PEEP". The greater the FRC is, with an airway pressure = atmospheric pressure, the lower the PEEP value required in order to obtain maximum oxygen transport. If the optimal PEEP value is exceeded the oxygen transport will fall because of a falling Qt (cardiac output) due to a reduction in venous return. CT and PVO2 will fall and VD/VT will increase. Increasing hyperinflation of the alveolae will result in a rising danger of alveolar rupture. The critical use of CPPV treatment means that the lungs may be safeguarded against high oxygen percents. The mortality of newborn infants with RDS (respiratory distress syndrome) has fallen considerably after the general introduction of CPPV and CPAP (continuous positive airway pressures). The same appears to be the case with adults suffering from ARI (acute respiratory insufficiency).

  20. Effect of PEEP on phosgene-induced lung edema: pilot study on dogs using protective ventilation strategies.

    PubMed

    Li, Wenli; Rosenbruch, Martin; Pauluhn, Jürgen

    2015-02-01

    Various therapeutic regimes have been proposed for treatment of phosgene-induced acute lung injury (P-ALI). Most of these treatments rely on late-stage supportive measures to maintain the oxygenation of the lung. This exploratory proof-of-concept study on Beagle dogs focused on protective positive end-expiratory pressure (PEEP) ventilation, initiated early at the yet asymptomatic stage after phosgene exposure. Conscious, spontaneously breathing dogs were head-only exposed to a potentially lethal inhalation dose of phosgene (870 ppm × min). Shortly after exposure, the dogs were anesthetized, intubated and then subjected to mechanical ventilation (PEEP; tidal volume (VT)=10-12 mL/kg body weight, 40 breaths/min) at 0, 4, or 12 cm H2O over a post-exposure period of 8h (one dog per setting). For reference, one additional dog received the same dose of phosgene without anesthesia and mechanical ventilation. Time-course changes of hematocrit, leukocytes, and thrombocytes were determined in peripheral blood. At necropsy, changes lung weights, bronchoalveolar lavage, and histology were used to assess the efficacy of treatment. The most salient outcome in the non-ventilated dog was a time-related hemoconcentration and leukocytosis and autopsy findings suggestive of pulmonary congestion and edema. The pulmonary epithelium of the major airways was generally intact; however, in their lumen inflammatory cells, cellular debris and mucus were present. Relative to the dog receiving no intervention, the lung edema was markedly alleviated by PEEP at both 4 and 12 cm H2O but not at 0 cm H2O PEEP. In summary, the time-dependent progression into a life-threatening pulmonary edema can effectively be suppressed by protective, low-pressure PEEP when implemented early enough after exposure to phosgene. However, due to the exploratory nature of this study, the findings may suggest an association between PEEP and protection from pulmonary edema. However, definite conclusions and

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

    PubMed Central

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

    2013-01-01

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

  2. Comparison of the effects of PEEP levels on respiratory mechanics and elimination of volatile anesthetic agents in patients undergoing laparoscopic cholecystectomy; a prospective, randomized, clinical trial.

    PubMed

    Arinalp, Hüsnü Mert; Bakan, Nurten; Karaören, Gülşah; Şahin, Ömer Torun; Çeliksoy, Emre

    2016-06-23

    In laparoscopic procedures, intraabdominal carbon dioxide (CO2) insufflation can cause decreased compliance, increased airway resistance, and impaired ventilation-perfusion ratios. We aimed to investigate the effects of intraoperative positive end-expiratory pressure (PEEP) treatment on respiratory dynamics and elimination time of volatile anesthetic agents. In the present study, 75 ASA I-II patients were randomized into 3 groups to receive 0 cmH2O PEEP (group I), 5 cmH2O PEEP (group II), or 8 cmH2O PEEP (group III). Hemodynamic parameters, peak and plateau inspiratory airway pressures (Ppeak, Pplateau), compliance values, the ratio of the fractions of inspired and expired concentration of sevoflurane (Fi/Fexp sevoflurane) at 1 MAC, times from 1 to 0.3 and 0.1 MAC and values for pulmonary function tests (PFT) were recorded. Ppeak and Pplateau in group III were higher; compliance values in group I and the extent of reduction in postoperative forced vital capacity (FVC) in group III were lower than those in the other groups (P < 0.05). No significant difference was observed between the groups regarding times from 1 to 0.3 MAC and times from 0.3 to 0.1 MAC. It was found that 8 cmH2O PEEP increased compliance without clinically significant pulmonary deterioration and that 8 cmH2O PEEP led to less impairment in postoperative PFTs compared to 0 and 5 cmH2O PEEP but had no effect on sevoflurane elimination time.

  3. Semantic analysis according to Peep Koort--a substance-oriented research methodology.

    PubMed

    Sivonen, Kerstin; Kasén, Anne; Eriksson, Katie

    2010-12-01

    The aim of this article is to describe the hermeneutic semantic analysis created by professor Peep Koort (1920-1977) and to discuss it as a methodology for research within caring science. The methodology is developed with a hermeneutic approach that differs from the traditions of semantic analysis in philosophy or linguistics. The research objects are core concepts and theoretical constructs (originally within the academic discipline of education science, later on within the academic discipline of caring science), focusing deeper understanding of essential meaning content when developing a discipline. The qualitative methodology of hermeneutic semantic analysis is described step by step as created by Koort, interpreted and developed by the authors. An etymological investigation and an analysis of synonymy between related concepts within a conceptual family guides the researcher to understand and discriminate conceptual dimensions of meaning content connected to the word studied, thus giving opportunities to summarise it in a theoretical definition, a discovery that can be tested in varying contexts. From a caring science perspective, we find the hermeneutic methodology of semantic analysis fruitful and suitable for researchers developing their understanding of core concepts and theoretical constructs connected to the development of the academic discipline.

  4. [Determination of cardiac output under PEEP-respiration with the "NCCOM 3" non-invasive bioimpedence monitor in comparison with the thermodilution method. A study in anesthetized dogs].

    PubMed

    Weber, J; Heidelmeyer, C F; Kubatz, E; Brückner, J B

    1986-12-01

    A new noninvasive cardiac output (CO) computer ("NCCOM 3") based on the bioimpedance principle was compared to a CO computer based on standard thermodilution measurements. Simultaneous measurements were made on dogs who were ventilated with or without positive end expiratory pressure (PEEP). There was no correlation of cardiac output measurements with the two methods (r = 0.10, n = 60). Comparing only measurements without PEEP yielded r = 0.41. Thermodilution measurements showed the well-known decline in cardiac output during PEEP, whereas the bioimpedance device recorded an increase in cardiac output. These differences were statistically significant. We conclude that the NCCOM 3 cannot at present replace the invasive standard methods of CO measurement in ventilated patients. A lack of differentiation of circulatory effects, thoracic gas volume, and intrathoracic fluid content is the most likely cause of the discrepancies seen.

  5. Multivariable fractional polynomial interaction to investigate continuous effect modifiers in a meta-analysis on higher versus lower PEEP for patients with ARDS

    PubMed Central

    Kasenda, Benjamin; Sauerbrei, Willi; Royston, Patrick; Mercat, Alain; Slutsky, Arthur S; Cook, Deborah; Guyatt, Gordon H; Brochard, Laurent; Richard, Jean-Christophe M; Stewart, Thomas E; Meade, Maureen; Briel, Matthias

    2016-01-01

    Objectives A recent individual patient data (IPD) meta-analysis suggested that patients with moderate or severe acute respiratory distress syndrome (ARDS) benefit from higher positive end-expiratory pressure (PEEP) ventilation strategies. However, thresholds for continuous variables (eg, hypoxaemia) are often arbitrary and linearity assumptions in regression approaches may not hold; the multivariable fractional polynomial interaction (MFPI) approach can address both problems. The objective of this study was to apply the MFPI approach to investigate interactions between four continuous patient baseline variables and higher versus lower PEEP on clinical outcomes. Setting Pooled data from three randomised trials in intensive care identified by a systematic review. Participants 2299 patients with acute lung injury requiring mechanical ventilation. Interventions Higher (N=1136) versus lower PEEP (N=1163) ventilation strategy. Outcome measures Prespecified outcomes included mortality, time to death and time-to-unassisted breathing. We examined the following continuous baseline characteristics as potential effect modifiers using MFPI: PaO2/FiO2 (arterial partial oxygen pressure/ fraction of inspired oxygen), oxygenation index, respiratory system compliance (tidal volume/(inspiratory plateau pressure−PEEP)) and body mass index (BMI). Results We found that for patients with PaO2/FiO2 below 150 mm Hg, but above 100 mm Hg or an oxygenation index above 12 (moderate ARDS), higher PEEP reduces hospital mortality, but the beneficial effect appears to level off for patients with very severe ARDS. Patients with mild ARDS (PaO2/FiO2 above 200 mm Hg or an oxygenation index below 10) do not seem to benefit from higher PEEP and might even be harmed. For patients with a respiratory system compliance above 40 mL/cm H2O or patients with a BMI above 35 kg/m2, we found a trend towards reduced mortality with higher PEEP, but there is very weak statistical confidence in

  6. Redistribution of blood flow and lung volume between lungs in lateral decubitus postures during unilateral atelectasis and PEEP.

    PubMed

    Chang, Hung; Lai-Fook, Stephen J; Domino, Karen B; Schimmel, Carmel; Hildebrandt, Jack; Lee, Shih-Chun; Kao, Chung-Cheng; Hsu, Jane-Yi; Robertson, H Thomas; Glenny, Robb W; Hlastala, Michael P

    2006-04-30

    The effect of left lung atelectasis on the regional distribution of blood flow (Q), ventilation (V(A)) and gas exchange on the right lung ventilated with 100% O2 was studied in anesthetized dogs in the lateral decubitus posture. Q and V(A) were measured in 1.7 ml lung volume pieces using injected and aerosolized fluorescent microspheres, respectively. Hypoxic pulmonary vasoconstriction (HPV) in the atelectatic lung shifted flow to the ventilated lung. The increased flow in the ventilated lung ensured adequate gas exchange, compensating for the hypoxemia due to shunt contributed by the atelectatic lung. Left lung atelectasis caused a compensatory increase in the ventilated lung FRC that was smaller in the right (RLD) than left (LLD) lateral posture, the effect of lung compression by the atelectatic lung and mediastinal contents in the RLD posture. The O2 deficit measured by (A-a)DO2 increased with left lung atelectasis and was exacerbated in the LLD posture by 10 cm H2O PEEP, a result of increased shunt caused by a shift in Q from the ventilated to the atelectatic lung. The PEEP-induced O2 deficit was eliminated with inversion to the RLD posture.

  7. Effect of Different Levels of Peep on Oxygenation during Non-Invasive Ventilation in Patients Submitted to CABG Surgery: Randomized Clinical Trial

    PubMed Central

    Cordeiro, André Luiz Lisboa; Gruska, Caroline Aparecida; Ysla, Pâmella; Queiroz, Amanda; Nogueira, Sarah Carvalho de Oliveira; Leite, Maria Clara; Freitas, Bruno; Guimarães, André Raimundo

    2017-01-01

    Introduction During and after coronary artery bypass grafting, a decline in multifactor lung function is observed. Due to this fact, some patients may benefit from non-invasive ventilation after extubation targeting lung expansion and consequently improved oxygenation. Objective To test the hypothesis that higher levels of positive end expiration pressure during non-invasive ventilation improves oxygenation in patients undergoing coronary artery bypass grafting. Methods A randomized clinical trial was conducted at Instituto Nobre de Cardiologia in Feira de Santana. On the first day after surgery, the patients were randomized: Group PEEP 10, Group PEEP 12 and Group PEEP 15 who underwent non-invasive ventilation with positive end expiration pressure level. All patients were submitted to analysis blood pressure oxygen (PaO2), arterial oxygen saturation (SaO2) and oxygenation index (PaO2/FiO2). Results Thirty patients were analyzed, 10 in each group, with 63.3% men with a mean age of 61.1±12.2 years. Mean pulmonary expansion pre-therapy PaO2 was generally 121.9±21.6 to 136.1±17.6 without statistical significance in the evaluation among the groups. This was also present in PaO2/FiO2 and SaO2. Statistical significance was only present in pre and post PEEP 15 when assessing the PaO2 and SaO2 (P=0.02). Conclusion Based on the findings of this study, non-invasive ventilation with PEEP 15 represented an improvement in oxygenation levels of patients undergoing coronary artery bypass grafting.

  8. NOAA People Empowered Products (PeEP): Combining social media with scientific models to provide eye-witness confirmed products

    NASA Astrophysics Data System (ADS)

    Codrescu, S.; Green, J. C.; Redmon, R. J.; Denig, W. F.; Kihn, E. A.

    2012-12-01

    NOAA products and alerts rely on combinations of models and data to provide the public with information regarding space and terrestrial weather hazards. This operational paradigm, while effective, neglects an abundant free source of measurements: millions of eyewitnesses viewing weather events. Here we present a prototype product that combines user reports with scientific model output and discuss the possibilities for creating a generic PeEP framework for use in a wide range of applications. We demonstrate the capabilities of a proto-PeEP that combines the OVATION prime auroral model running at the NOAA National Geophysical Data Center with Twitter reports of observable aurora. The combined product displays the model aurora in real time on Google Earth with markers showing the location and text of tweets from people actually observing the aurora. We discuss how the application can be extended and incorporated to other space weather products such as ionospheric induced GPS errors and radiation related satellite anomalies.

  9. Minimizing atelectasis formation during general anaesthesia—oxygen washout is a non-essential supplement to PEEP

    PubMed Central

    Östberg, Erland; Auner, Udo; Enlund, Mats; Zetterström, Henrik; Edmark, Lennart

    2017-01-01

    Background Following preoxygenation and induction of anaesthesia, most patients develop atelectasis. We hypothesized that an immediate restoration to a low oxygen level in the alveoli would prevent atelectasis formation and improve oxygenation during the ensuing anaesthesia. Methods We randomly assigned 24 patients to either a control group (n = 12) or an intervention group (n = 12) receiving an oxygen washout procedure directly after intubation. Both groups were, depending on body mass index, ventilated with a positive end-expiratory pressure (PEEP) of 6–8 cmH2O during surgery. The atelectasis area was studied by computed tomography before emergence. Oxygenation levels were evaluated by measuring blood gases and calculating estimated venous admixture (EVA). Results The atelectasis areas expressed as percentages of the total lung area were 2.0 (1.5–2.7) (median [interquartile range]) and 1.8 (1.4–3.3) in the intervention and control groups, respectively. The difference was non-significant, and also oxygenation was similar between the two groups. Compared to oxygenation before the start of anaesthesia, oxygenation at the end of surgery was improved in the intervention group, mean (SD) EVA from 7.6% (6.6%) to 3.9% (2.9%) (P = .019) and preserved in the control group, mean (SD) EVA from 5.0% (5.3%) to 5.6% (7.1%) (P = .59). Conclusion Although the oxygen washout restored a low pulmonary oxygen level within minutes, it did not further reduce atelectasis size. Both study groups had small atelectasis and good oxygenation. These results suggest that a moderate PEEP alone is sufficient to minimize atelectasis and maintain oxygenation in healthy patients. PMID:28434271

  10. 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

  11. NOAA People Empowered Products (PeEP): Combining social media with scientific models to provide eye-witness confirmed products

    NASA Astrophysics Data System (ADS)

    Codrescu, S.; Green, J. C.; Redmon, R. J.; Minor, K.; Denig, W. F.; Kihn, E. A.

    2013-12-01

    NOAA products and alerts rely on combinations of models and data to provide the public with information regarding space and terrestrial weather phenomena and hazards. This operational paradigm, while effective, neglects an abundant free source of measurements: millions of eyewitnesses viewing weather events. We demonstrate the capabilities of a prototype People Empowered Product (PeEP) that combines the OVATION prime auroral model running at the NOAA National Geophysical Data Center with Twitter reports of observable aurora. We introduce an algorithm for scoring Tweets based on keywords to improve the signal to noise of this dynamic data source. We use the location of the aurora derived from this new database of crowd sourced observations to validate the OVATION model for use in auroral forecasting. The combined product displays the model aurora in real time with markers showing the location and text of tweets from people actually observing the aurora. We discuss how the application might be extended to other space weather products such as radiation related satellite anomalies.

  12. Effects of manual rib-cage compression versus PEEP-ZEEP maneuver on respiratory system compliance and oxygenation in patients receiving mechanical ventilation.

    PubMed

    Santos, Flavio Renato Antunes Dos; Schneider Júnior, Luiz Carlos; Forgiarini Junior, Luiz Alberto; Veronezi, Jefferson

    2009-06-01

    Patients unable to perform breathing functions may be submitted to invasive mechanical ventilation. Chest physiotherapy acts directly on the treatment of these patients for the purpose of improving their lung function. The objective of this study was to evaluate the effects of manual rib-cage compression versus the positive end expiratory pressure-zero end expiratory pressure (PEEP-ZEEP) maneuver, on compliance of the respiratory system and oxygenation in patients under invasive mechanical ventilation. A double centric, prospective, randomized and crossover study, with patients under invasive mechanical ventilation, in controlled mode for more than 48 hours was carried out. The protocols of chest physiothe-rapy were randomly applied at an interval of 24 hours. Data of respiratory system compliance and oxygenation were collected before application of the protocols and 30 minutes after. Twelve patients completed the study. Intragroup analysis, for both techniques showed a statistically significant difference in tidal volume (p=0.002), static compliance (p=0.002) and dynamic compliance (p=0.002). In relation to oxygenation, in the group of manual rib-cage compression, peripheral oxygen saturation increased with a significant difference (p=0.011). Manual rib-cage compression and PEEP-ZEEP maneuver have positive clinical effects. In relation to oxygenation we found a favorable behavior of peripheral oxygen saturation in the group of manual rib-cage compression.

  13. The Peep Show

    ERIC Educational Resources Information Center

    Gamble, David L.

    2010-01-01

    Three years ago, the author and Linda Arbuckle (University of Florida ceramic professor and internationally known majolica clay artist) were on the phone discussing how electric kilns just don't have any artistic design flair to them. The round kiln has basic properties that allow it to function properly, but its looks are far from exciting. They…

  14. The Peep Show

    ERIC Educational Resources Information Center

    Gamble, David L.

    2010-01-01

    Three years ago, the author and Linda Arbuckle (University of Florida ceramic professor and internationally known majolica clay artist) were on the phone discussing how electric kilns just don't have any artistic design flair to them. The round kiln has basic properties that allow it to function properly, but its looks are far from exciting. They…

  15. Respiratory and haemodynamic effects of conventional volume controlled PEEP ventilation, pressure regulated volume controlled ventilation and low frequency positive pressure ventilation with extracorporeal carbon dioxide removal in pigs with acute ARDS.

    PubMed

    Kesecioglu, J; Telci, L; Esen, F; Akpir, K; Tütüncü, A S; Denkel, T; Erdmann, W; Lachmann, B

    1994-11-01

    The purpose of this study was to evaluate whether any benefit of low frequency positive pressure ventilation with extracorporeal carbon dioxide removal (LFPPV-ECCO2R) existed over either volume controlled ventilation (VCV) with measured best-PEEP or pressure regulated volume controlled ventilation (PRVCV) with an inspiration/expiration (I/E) ratio of 4:1, with respect to arterial oxygenation, lung mechanics and haemodynamics, in acute respiratory failure. Fifteen adult pigs were used for the study. Respiratory failure was induced by surfactant depletion by repeated lung lavage. The different therapeutic approaches were applied randomly to each pig for 1 h. Measurements of gas exchange, airway pressures and haemodynamics were performed during ventilatory and haemodynamic steady state. Paco2 was kept constant in all modes. At almost similar total-PEEP, Pao2 values were significantly higher with LFPPV-ECCO2R compared to VCV with best-PEEP. Peak inspiratory pressure (PIP) and intrapulmonary pressure amplitude defined as the difference between PIP and total-PEEP were significantly lower with PRVCV and LFPPV-ECCO2R compared to VCV with best-PEEP. There was no significant difference between the modes concerning cardiocirculatory parameters. PRVCV with I/E ratio of 4:1 and LFPPV-ECCO2R proved to be better modes to achieve better gas exchange and lower PIP at lower intrapulmonary pressure amplitudes. It is concluded that PRVCV is an adequate form of treatment under these experimental conditions imitating acute respiratory failure, without necessitating other invasive measures.

  16. Investigation of continuous effect modifiers in a meta-analysis on higher versus lower PEEP in patients requiring mechanical ventilation - protocol of the ICEM study

    PubMed Central

    2014-01-01

    Background Categorizing an inherently continuous predictor in prognostic analyses raises several critical methodological issues: dependence of the statistical significance on the number and position of the chosen cut-point(s), loss of statistical power, and faulty interpretation of the results if a non-linear association is incorrectly assumed to be linear. This also applies to a therapeutic context where investigators of randomized clinical trials (RCTs) are interested in interactions between treatment assignment and one or more continuous predictors. Methods/Design Our goal is to apply the multivariable fractional polynomial interaction (MFPI) approach to investigate interactions between continuous patient baseline variables and the allocated treatment in an individual patient data meta-analysis of three RCTs (N = 2,299) from the intensive care field. For each study, MFPI will provide a continuous treatment effect function. Functions from each of the three studies will be averaged by a novel meta-analysis approach for functions. We will plot treatment effect functions separately for each study and also the averaged function. The averaged function with a related confidence interval will provide a suitable basis to assess whether a continuous patient characteristic modifies the treatment comparison and may be relevant for clinical decision-making. The compared interventions will be a higher or lower positive end-expiratory pressure (PEEP) ventilation strategy in patients requiring mechanical ventilation. The continuous baseline variables body mass index, PaO2/FiO2, respiratory compliance, and oxygenation index will be the investigated potential effect modifiers. Clinical outcomes for this analysis will be in-hospital mortality, time to death, time to unassisted breathing, and pneumothorax. Discussion This project will be the first meta-analysis to combine continuous treatment effect functions derived by the MFPI procedure separately in each of several RCTs

  17. Production of Energy Efficient Preform Structures (PEEPS)

    SciTech Connect

    Dr. John A. Baumann

    2012-06-08

    Due to its low density, good structural characteristics, excellent fabrication properties, and attractive appearance, aluminum metal and its alloys continue to be widely utilized. The transportation industry continues to be the largest consumer of aluminum products, with aerospace as the principal driver for this use. Boeing has long been the largest single company consumer of heat-treated aluminum in the U.S. The extensive use of aluminum to build aircraft and launch vehicles has been sustained, despite the growing reliance on more structurally efficient carbon fiber reinforced composite materials. The trend in the aerospace industry over the past several decades has been to rely extensively on large, complex, thin-walled, monolithic machined structural components, which are fabricated from heavy billets and thick plate using high speed machining. The use of these high buy-to-fly ratio starting product forms, while currently cost effective, is energy inefficient, with a high environmental impact. The widespread implementation of Solid State Joining (SSJ) technologies, to produce lower buy-to-fly ratio starting forms, tailored to each specific application, offers the potential for a more sustainable manufacturing strategy, which would consume less energy, require less material, and reduce material and manufacturing costs. One objective of this project was to project the energy benefits of using SSJ techniques to produce high-performance aluminum structures if implemented in the production of the world fleet of commercial aircraft. A further objective was to produce an energy consumption prediction model, capable of calculating the total energy consumption, solid waste burden, acidification potential, and CO2 burden in producing a starting product form - whether by conventional or SSJ processes - and machining that to a final part configuration. The model needed to be capable of computing and comparing, on an individual part/geometry basis, multiple possible manufacturing pathways, to identify the best balance of energy consumption and environmental impact. This model has been created and populated with energy consumption data for individual SSJ processes and process platforms. Technology feasibility cases studies were executed, to validate the model, and confirm the ability to create lower buy-to-fly ratio performs and machine these to final configuration aircraft components. This model can now be used as a tool to select manufacturing pathways that offer significant energy savings and, when coupled with a cost model, drive implementation of the SSJ processes.

  18. Of gossips, eavesdroppers, and peeping toms

    PubMed Central

    Francis, Huw W S

    1982-01-01

    British accounts of medical ethics concentrate on confidentiality to the exclusion of wider questions of privacy. This paper argues for consideration of privacy within medical ethics, and illustrates through the television series `Hospital', what may go awry when this wider concept is forgotten. PMID:7131499

  19. PEEP: A Pascal Environment for Experiments on Programming.

    DTIC Science & Technology

    1982-09-01

    tember 1981. [FAIR801 Fairley , R . E., "Ada Debugging and Testing Support Environment," SIGPLAN Notices, Vol.15, No.11, No- vember 1980, pp.16-25...1979. IRIDD801 Riddle, W. E. and Fairley , R . E. (Eds.), Software Development Tools, Springer-Verlag, Germany, 1980. [RITC781 Ritchie, D. M. and Thompson

  20. Plurilingual Ethos: A Peep into the Sociology of Language.

    ERIC Educational Resources Information Center

    Khubchandani, Lachman M.

    1998-01-01

    Issues in the study of bilingualism and multilingualism in India and Pakistan are examined, including the delineation of linguistic boundaries, defining a society that is multicultural and yet has developed a "communication ethos" based on a core of common experience, the difficulty in interpreting language role and defining language…

  1. "Scientific peep show": the human body in contemporary science museums.

    PubMed

    Canadelli, Elena

    2011-01-01

    The essay focuses on the discourse about the human body developed by contemporary science museums with educational and instructive purposes directed at the general public. These museums aim mostly at mediating concepts such as health and prevention. The current scenario is linked with two examples of past museums: the popular anatomical museums which emerged during the 19th century and the health museums thrived between 1910 and 1940. On the museological path about the human body self-care we went from the emotionally involving anatomical Venuses to the inexpressive Transparent Man, from anatomical specimens of ill organs and deformed subjects to the mechanical and electronic models of the healthy body. Today the body is made transparent by the new medical diagnostics and by the latest discoveries of endoscopy. The way museums and science centers presently display the human body involves computers, 3D animation, digital technologies, hands-on models of large size human parts.

  2. A Peep into the Uncertainty-Complexity-Relevance Modeling Trilemma through Global Sensitivity and Uncertainty Analysis

    NASA Astrophysics Data System (ADS)

    Munoz-Carpena, R.; Muller, S. J.; Chu, M.; Kiker, G. A.; Perz, S. G.

    2014-12-01

    Model Model complexity resulting from the need to integrate environmental system components cannot be understated. In particular, additional emphasis is urgently needed on rational approaches to guide decision making through uncertainties surrounding the integrated system across decision-relevant scales. However, in spite of the difficulties that the consideration of modeling uncertainty represent for the decision process, it should not be avoided or the value and science behind the models will be undermined. These two issues; i.e., the need for coupled models that can answer the pertinent questions and the need for models that do so with sufficient certainty, are the key indicators of a model's relevance. Model relevance is inextricably linked with model complexity. Although model complexity has advanced greatly in recent years there has been little work to rigorously characterize the threshold of relevance in integrated and complex models. Formally assessing the relevance of the model in the face of increasing complexity would be valuable because there is growing unease among developers and users of complex models about the cumulative effects of various sources of uncertainty on model outputs. In particular, this issue has prompted doubt over whether the considerable effort going into further elaborating complex models will in fact yield the expected payback. New approaches have been proposed recently to evaluate the uncertainty-complexity-relevance modeling trilemma (Muller, Muñoz-Carpena and Kiker, 2011) by incorporating state-of-the-art global sensitivity and uncertainty analysis (GSA/UA) in every step of the model development so as to quantify not only the uncertainty introduced by the addition of new environmental components, but the effect that these new components have over existing components (interactions, non-linear responses). Outputs from the analysis can also be used to quantify system resilience (stability, alternative states, thresholds or tipping points) in the face of environmental and anthropogenic change (Perz, Muñoz-Carpena, Kiker and Holt, 2013), and through MonteCarlo mapping potential management activities over the most important factors or processes to influence the system towards behavioral (desirable) outcomes (Chu-Agor, Muñoz-Carpena et al., 2012).

  3. Effect of CPAP on intrinsic PEEP, inspiratory effort, and lung volume in severe stable COPD

    PubMed Central

    O'Donoghue, F; Catcheside, P; Jordan, A; Bersten, A; McEvoy, R

    2002-01-01

    Background: Intrinsic positive end expiratory pressure (PEEPi) constitutes an inspiratory threshold load on the respiratory muscles, increasing work of breathing. The role of continuous positive airway pressure (CPAP) in alleviating PEEPi in patients with severe stable chronic obstructive pulmonary disease is uncertain. This study examined the effect of CPAP on the inspiratory threshold load, muscle effort, and lung volume in this patient group. Methods: Nine patients were studied at baseline and with CPAP increasing in increments of 1 cm H2O to a maximum of 10 cm H2O. Breathing pattern and minute ventilation (I), dynamic PEEPi, expiratory muscle activity, diaphragmatic (PTPdi/min) and oesophageal (PTPoes/min) pressure-time product per minute, integrated diaphragmatic (EMGdi) and intercostal EMG (EMGic) and end expiratory lung volume (EELV) were measured. Results: Expiratory muscle activity was present at baseline in one subject. In the remaining eight, PEEPi was reduced from a mean (SE) of 2.9 (0.6) cm H2O to 0.9 (0.1) cm H2O (p<0.05). In two subjects expiratory muscle activity contributed to PEEPi at higher pressures. There were no changes in respiratory pattern but I increased from 9.2 (0.6) l/min to 10.7 (1.1) l/min (p<0.05). EMGdi remained stable while EMGic increased significantly. PTPoes/min decreased, although this did not reach statistical significance. PTPdi/min decreased significantly from 242.1 (32.1) cm H2O.s/min to 112.9 (21.7) cm H2O.s/min). EELV increased by 1.1 (0.3) l (p<0.01). Conclusion: High levels of CPAP reduce PEEPi and indices of muscle effort in patients with severe stable COPD, but only at the expense of substantial increases in lung volume. PMID:12037230

  4. A peep into mitochondrial disorder: multifaceted from mitochondrial DNA mutations to nuclear gene modulation.

    PubMed

    Chen, Chao; Chen, Ye; Guan, Min-Xin

    2015-12-01

    Mitochondrial genome is responsible for multiple human diseases in a maternal inherited pattern, yet phenotypes of patients in a same pedigree frequently vary largely. Genes involving in epigenetic modification, RNA processing, and other biological pathways, rather than "threshold effect" and environmental factors, provide more specific explanation to the aberrant phenotype. Thus, the double hit theory, mutations both in mitochondrial DNA and modifying genes aggravating the symptom, throws new light on mitochondrial dysfunction processes. In addition, mitochondrial retrograde signaling pathway that leads to reconfiguration of cell metabolism to adapt defects in mitochondria may as well play an active role. Here we review selected examples of modifier genes and mitochondrial retrograde signaling in mitochondrial disorders, which refine our understanding and will guide the rational design of clinical therapies.

  5. Peeping at TOMs-Diverse Entry Gates to Mitochondria Provide Insights into the Evolution of Eukaryotes.

    PubMed

    Mani, Jan; Meisinger, Chris; Schneider, André

    2016-02-01

    Mitochondria are essential for eukaryotic life and more than 95% of their proteins are imported as precursors from the cytosol. The targeting signals for this posttranslational import are conserved in all eukaryotes. However, this conservation does not hold true for the protein translocase of the mitochondrial outer membrane that serves as entry gate for essentially all precursor proteins. Only two of its subunits, Tom40 and Tom22, are conserved and thus likely were present in the last eukaryotic common ancestor. Tom7 is found in representatives of all supergroups except the Excavates. This suggests that it was added to the core of the translocase after the Excavates segregated from all other eukaryotes. A comparative analysis of the biochemically and functionally characterized outer membrane translocases of yeast, plants, and trypanosomes, which represent three eukaryotic supergroups, shows that the receptors that recognize the conserved import signals differ strongly between the different systems. They present a remarkable example of convergent evolution at the molecular level. The structural diversity of the functionally conserved import receptors therefore provides insight into the early evolutionary history of mitochondria.

  6. The Application of High-Resolution Electron Microscopy to Problems in Solid State Chemistry: The Exploits of a Peeping TEM.

    ERIC Educational Resources Information Center

    Eyring, LeRoy

    1980-01-01

    Describes methods for using the high-resolution electron microscope in conjunction with other tools to reveal the identity and environment of atoms. Problems discussed include the ultimate structure of real crystalline solids including defect structure and the mechanisms of chemical reactions. (CS)

  7. Act on Gender: A Peep into Intra-Household Water Use in the Australian Capital Territory (ACT) Region

    ERIC Educational Resources Information Center

    Lahiri-Dutt, Kuntala; Harriden, Kate

    2008-01-01

    Intra-household water use and management from a gender perspective has remained a relatively under-researched theme in developed countries. Australia is no exception, with the lack of research particularly evident in the many rural and peri-urban communities. These communities have experienced significant water scarcity in recent years. In this…

  8. Act on Gender: A Peep into Intra-Household Water Use in the Australian Capital Territory (ACT) Region

    ERIC Educational Resources Information Center

    Lahiri-Dutt, Kuntala; Harriden, Kate

    2008-01-01

    Intra-household water use and management from a gender perspective has remained a relatively under-researched theme in developed countries. Australia is no exception, with the lack of research particularly evident in the many rural and peri-urban communities. These communities have experienced significant water scarcity in recent years. In this…

  9. Peeping into human renal calcium oxalate stone matrix: characterization of novel proteins involved in the intricate mechanism of urolithiasis.

    PubMed

    Aggarwal, Kanu Priya; Tandon, Simran; Naik, Pradeep Kumar; Singh, Shrawan Kumar; Tandon, Chanderdeep

    2013-01-01

    The increasing number of patients suffering from urolithiasis represents one of the major challenges which nephrologists face worldwide today. For enhancing therapeutic outcomes of this disease, the pathogenic basis for the formation of renal stones is the need of hour. Proteins are found as major component in human renal stone matrix and are considered to have a potential role in crystal-membrane interaction, crystal growth and stone formation but their role in urolithiasis still remains obscure. Proteins were isolated from the matrix of human CaOx containing kidney stones. Proteins having MW>3 kDa were subjected to anion exchange chromatography followed by molecular-sieve chromatography. The effect of these purified proteins was tested against CaOx nucleation and growth and on oxalate injured Madin-Darby Canine Kidney (MDCK) renal epithelial cells for their activity. Proteins were identified by Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF MS) followed by database search with MASCOT server. In silico molecular interaction studies with CaOx crystals were also investigated. Five proteins were identified from the matrix of calcium oxalate kidney stones by MALDI-TOF MS followed by database search with MASCOT server with the competence to control the stone formation process. Out of which two proteins were promoters, two were inhibitors and one protein had a dual activity of both inhibition and promotion towards CaOx nucleation and growth. Further molecular modelling calculations revealed the mode of interaction of these proteins with CaOx at the molecular level. We identified and characterized Ethanolamine-phosphate cytidylyltransferase, Ras GTPase-activating-like protein, UDP-glucose:glycoprotein glucosyltransferase 2, RIMS-binding protein 3A, Macrophage-capping protein as novel proteins from the matrix of human calcium oxalate stone which play a critical role in kidney stone formation. Thus, these proteins having potential to modulate calcium oxalate crystallization will throw light on understanding and controlling urolithiasis in humans.

  10. Giving peeps to my props: Using 3D printing to shed new light on particle transport in fractured rock.

    NASA Astrophysics Data System (ADS)

    Walsh, S. D.; Du Frane, W. L.; Vericella, J. J.; Aines, R. D.

    2014-12-01

    Smart tracers and smart proppants promise new methods for sensing and manipulating rock fractures. However, the correct use and interpretation of these technologies relies on accurate models of their transport. Even for less exotic particles, the factors controlling particle transport through fractures are poorly understood. In this presentation, we will describe ongoing research at Lawrence Livermore National Laboratory into the transport properties of particles in natural rock fractures. Using three dimensional printing techniques, we create clear-plastic reproductions of real-world fracture surfaces, thereby enabling direct observation of the particle movement. We will also discuss how particle tracking of dense particle packs can be further enhanced by using such specially tailored flow cells in combination with micro-encapsulated tracer particles. Experimental results investigating the transport behavior of smart tracers and proppants close to the neutrally buoyant limit will be presented and we will describe how data from these experiments can be used to improve large-scale models of particle transport in fractures. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  11. A randomized pilot study comparing the role of PEEP, O2 flow, and high-flow air for weaning of ventilatory support in very low birth weight infants.

    PubMed

    Yang, Chang-Yo; Yang, Mei-Chin; Chu, Shih-Ming; Chiang, Ming-Chou; Lien, Reyin

    2017-09-06

    There is a lack of evidence to guide step-wise weaning of positive pressure respiratory support for premature infants. This study sought to compare the efficacy of three weaning protocols we designed to facilitate weaning of very low birth weight (VLBW, less than 1500 g) preterm infants from nasal continuous positive airway pressure (NCPAP) support. This was a prospective, randomized, controlled trial of VLBW preterm infants who received positive pressure ventilatory support in our neonatal intensive care unit (NICU) from April 2008 through March 2009. When these infants were weaned to CPAP as their last step of respiratory support, they would be randomly assigned to one of the following three groups as their further weaning methods (M): (M1) CPAP group, (M2) O2 flow group, and (M3) air flow group. The time period they needed to wean off any kind of respiratory support, as well as the likelihood of developing relevant prematurity related morbidities, were compared among patients using different weaning modalities. 181 patients were enrolled in the study. Their gestational age (GA) and birth weight (BW) were 29.1 ± 2.5, 28.7 ± 2.4, 28.7 ± 2.4 (mean ± SD) weeks and 1142 ± 232, 1099 ± 234, 1083 ± 219 g, in M1, M2 and M3, respectively. The time (period) needed to wean off support was 16.0 ± 10.0 days (M1), 11.6 ± 6.4 days (M2), and 15.0 ± 8.9 days (M3), respectively (p = .033). Incidence of retinopathy of prematurity (ROP) and bronchopulmonary dysplasia (BPD) were both significantly higher in the O2 flow group (p = .048). Although using low oxygen flow significantly shortens CPAP weaning time, it may increase risks of BPD and ROP, both known to be related to oxygen toxicity. Unless the infant has BPD and is O2-dependent, clinicians should consider using air flow or just splinting with no support at all when weaning NCPAP. Copyright © 2017. Published by Elsevier B.V.

  12. Repeated thermo-sterilisation further affects the reliability of positive end-expiratory pressure valves.

    PubMed

    Hartung, Julia Christine; Schmölzer, Georg; Schmalisch, Gerd; Roehr, Charles Christoph

    2013-09-01

    Positive end-expiratory pressure (PEEP) valves are used together with self-inflating bags (SIB) to provide a preset PEEP during manual ventilation. It has recently been shown that these valves deliver highly variable levels of PEEP. We hypothesised that material fatigue due to repeated thermo-sterilisation (TS) may contribute to varying reliability of PEEP valves. In a laboratory study 10 new PEEP valves were tested before and after 10, 20 and 30 cycles of routine TS (7 min at 134°C) by using a neonatal lung model (compliance 0.2 mL/kPa). Settings were positive inflation pressure = 20 and 40 cm H(2)O, PEEP = 5 and 10 cm H(2)O, respiratory rate = 40 and 60/min, flow = 8l/min. PEEP was recorded using a respiratory function monitor. Before TS, a mean (standard deviation) PEEP of 4.0 (0.9) and 7.7 (1.0) cm H(2)O was delivered by the 10 valves when the PEEP was set to 5 and 10 cm H(2)O, respectively. One new valve only delivered 2.0 (0.0) and 5.0 (0.0) cm H(2)O when the PEEP was adjusted to 5 and 10 cm H(2)O, respectively. Four of the 10 investigated valves showed significant variations in PEEP (coefficient of variation >10%) throughout the autoclaving process. One valve completely lost its function after the 20th TS. Common defects were tears in the softer materials or displacement of the rubber seal. Six of the 10 valves continued to provide PEEP in spite of repeated TS. The reliability of PEEP valves is affected by repeated TS. Multi-use PEEP valves should be tested for reliable PEEP provision following TS. © 2013 The Authors. Journal of Paediatrics and Child Health © 2013 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

  13. Compliance versus dead space for optimum positive end expiratory pressure determination in acute respiratory distress syndrome

    PubMed Central

    El-Baradey, Ghada Fouad; El-Shamaa, Nagat Sayed

    2014-01-01

    Objective: To Compare compliance versus dead space (Vd) targeted positive end-expiratory pressure (PEEP) as regard its effect on lung mechanics and oxygenation. Materials and Methods: This study was carried out on 30 adult acute respiratory distress syndrome patients. The ventilator was initially set on volume controlled with tidal volume (Vt) 7 mL/kg predicted body weight (PBW), inspiratory plateau pressure (Ppl) <30 cm H2 O. If the Ppl was >30 cm H2 O with a TV of 6 mL/kg PBW, a step-wise Vt reduction of 1 mL/kg PBW to as low as 4 mL/kg/PBW was allowed. Respiratory rate adjusted to maintain pH 7.30-7.45. FiO2 start at 100%. Best PEEP determined at 2 points, one by titrating PEEP until reaching the highest static compliance (Cst) (PEEP Cst) and the other one is at the lowest Vd/Vt (PEEP Vd/Vt). The following data measured before and 30 min after setting PEEP Cst and PEEP Vd/Vt. Cst, PaCO2 - PetCO2, Vd/Vt, PaO2 /FiO2, Ppl, heart rate, mean arterial pressure and oxygen saturation. Results: optimum PEEP determined by Vd/Vt was significantly (P < 0.05) lower than the optimum PEEP determined by Cst. Best PEEP Vd/Vt showed a significant decrease (P < 0.05) in Cst, PaCO2 - PetCO2, Vd/Vt and Ppl in comparison with best PEEP Cst. The PaO2 /FiO2 showed a significant increase (P < 0.05) with best PEEP Vd/Vt in comparison with best PEEP Cst. Conclusion: Vd guided PEEP improved compliance and oxygenation with less Ppl. Hence, its use as a guide for best PEEP determination may be useful. PMID:25136189

  14. Bedside Contribution of Electrical Impedance Tomography to Setting Positive End-Expiratory Pressure for Extracorporeal Membrane Oxygenation-treated Patients with Severe Acute Respiratory Distress Syndrome.

    PubMed

    Franchineau, Guillaume; Bréchot, Nicolas; Lebreton, Guillaume; Hekimian, Guillaume; Nieszkowska, Ania; Trouillet, Jean-Louis; Leprince, Pascal; Chastre, Jean; Luyt, Charles-Edouard; Combes, Alain; Schmidt, Matthieu

    2017-08-15

    Optimal positive end-expiratory pressure (PEEP) is unknown in patients with severe acute respiratory distress syndrome (ARDS) on extracorporeal membrane oxygenation receiving mechanical ventilation with very low tidal volume. To evaluate the ability of electrical impedance tomography (EIT) to monitor a PEEP trial and to derive from EIT the best compromise PEEP in this setting. A decremental PEEP trial (20-0 cm H2O) in 5 cm H2O steps was monitored by EIT, with lung images divided into four ventral-to-dorsal horizontal regions of interest. The EIT-based PEEP providing the best compromise between overdistention and collapsed zones was arbitrarily defined as the lowest pressure able to limit EIT-assessed collapse to less than or equal to 15% with the least overdistention. Driving pressure was maintained constant at 14 cm H2O in pressure controlled mode. Tidal volume, static compliance, tidal impedance variation, end-expiratory lung impedance, and their respective regional distributions were visualized at each PEEP level in 15 patients on extracorporeal membrane oxygenation. Low tidal volume (2.9-4 ml/kg ideal body weight) and poor compliance (12.1-18.7 ml/cm H2O) were noted, with significantly higher tidal volume and compliance at PEEP10 and PEEP5 than PEEP20. EIT-based best compromise PEEPs were 15, 10, and 5 cm H2O for seven, six, and two patients, respectively, whereas PEEP20 and PEEP0 were never selected. The broad variability in optimal PEEP observed in these patients with severe ARDS under extracorporeal membrane oxygenation reinforces the need for personalized titration of ventilation settings. EIT may be an interesting noninvasive bedside tool to provide real-time monitoring of the PEEP impact in these patients.

  15. 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).

  16. Effects of positive end-expiratory pressure titration and recruitment maneuver on lung inflammation and hyperinflation in experimental acid aspiration-induced lung injury.

    PubMed

    Ambrosio, Aline M; Luo, Rubin; Fantoni, Denise T; Gutierres, Claudia; Lu, Qin; Gu, Wen-Jie; Otsuki, Denise A; Malbouisson, Luiz M S; Auler, Jose O C; Rouby, Jean-Jacques

    2012-12-01

    In acute lung injury positive end-expiratory pressure (PEEP) and recruitment maneuver are proposed to optimize arterial oxygenation. The aim of the study was to evaluate the impact of such a strategy on lung histological inflammation and hyperinflation in pigs with acid aspiration-induced lung injury. Forty-seven pigs were randomly allocated in seven groups: (1) controls spontaneously breathing; (2) without lung injury, PEEP 5 cm H2O; (3) without lung injury, PEEP titration; (4) without lung injury, PEEP titration + recruitment maneuver; (5) with lung injury, PEEP 5 cm H2O; (6) with lung injury, PEEP titration; and (7) with lung injury, PEEP titration + recruitment maneuver. Acute lung injury was induced by intratracheal instillation of hydrochloric acid. PEEP titration was performed by incremental and decremental PEEP from 5 to 20 cm H2O for optimizing arterial oxygenation. Three recruitment maneuvers (pressure of 40 cm H2O maintained for 20 s) were applied to the assigned groups at each PEEP level. Proportion of lung inflammation, hemorrhage, edema, and alveolar wall disruption were recorded on each histological field. Mean alveolar area was measured in the aerated lung regions. Acid aspiration increased mean alveolar area and produced alveolar wall disruption, lung edema, alveolar hemorrhage, and lung inflammation. PEEP titration significantly improved arterial oxygenation but simultaneously increased lung inflammation in juxta-diaphragmatic lung regions. Recruitment maneuver during PEEP titration did not induce additional increase in lung inflammation and alveolar hyperinflation. In a porcine model of acid aspiration-induced lung injury, PEEP titration aimed at optimizing arterial oxygenation, substantially increased lung inflammation. Recruitment maneuvers further improved arterial oxygenation without additional effects on inflammation and hyperinflation.

  17. Changes in Positive End-Expiratory Pressure Alter the Distribution of Ventilation within the Lung Immediately after Birth in Newborn Rabbits

    PubMed Central

    Kitchen, Marcus J.; Siew, Melissa L.; Wallace, Megan J.; Fouras, Andreas; Lewis, Robert A.; Yagi, Naoto; Uesugi, Kentaro; te Pas, Arjan B.; Hooper, Stuart B.

    2014-01-01

    Current recommendations suggest the use of positive end-expiratory pressures (PEEP) to assist very preterm infants to develop a functional residual capacity (FRC) and establish gas exchange at birth. However, maintaining a consistent PEEP is difficult and so the lungs are exposed to changing distending pressures after birth, which can affect respiratory function. Our aim was to determine how changing PEEP levels alters the distribution of ventilation within the lung. Preterm rabbit pups (28 days gestation) were delivered and mechanically ventilated with one of three strategies, whereby PEEP was changed in sequence; 0-5-10-5-0 cmH2O, 5-10-0-5-0 cmH2O or 10-5-0-10-0 cmH2O. Phase contrast X-ray imaging was used to analyse the distribution of ventilation in the upper left (UL), upper right (UR), lower left (LL) and lower right (LR) quadrants of the lung. Initiating ventilation with 10PEEP resulted in a uniform increase in FRC throughout the lung whereas initiating ventilation with 5PEEP or 0PEEP preferentially aerated the UR than both lower quadrants (p<0.05). Consequently, the relative distribution of incoming VT was preferentially directed into the lower lobes at low PEEP, primarily due to the loss of FRC in those lobes. Following ventilation at 10PEEP, the distribution of air at end-inflation was uniform across all quadrants and remained so regardless of the PEEP level. Uniform distribution of ventilation can be achieved by initiating ventilation with a high PEEP. After the lungs have aerated, small and stepped reductions in PEEP result in more uniform changes in ventilation. PMID:24690890

  18. 76 FR 44044 - National Register of Historic Places; Notification of Pending Nominations and Related Actions

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-22

    ...--Lake Sangraco Boathouse Complex, Address Restricted, Denver Larimer County Peep O Day Park, 5445 Wild...., Evansville WYOMING Sheridan County Sheridan County Fairgrounds Historic District, 1753 Victoria St., Sheridan...

  19. Assessment of respiratory system compliance with electrical impedance tomography using a positive end-expiratory pressure wave maneuver during pressure support ventilation: a pilot clinical study.

    PubMed

    Becher, Tobias H; Bui, Simon; Zick, Günther; Bläser, Daniel; Schädler, Dirk; Weiler, Norbert; Frerichs, Inéz

    2014-12-10

    Assessment of respiratory system compliance (Crs) can be used for individual optimization of positive end-expiratory pressure (PEEP). However, in patients with spontaneous breathing activity, the conventional methods for Crs measurement are inaccurate because of the variable muscular pressure of the patient. We hypothesized that a PEEP wave maneuver, analyzed with electrical impedance tomography (EIT), might be suitable for global and regional assessment of Crs during assisted spontaneous breathing. After approval of the local ethics committee, we performed a pilot clinical study in 18 mechanically ventilated patients (61 ± 16 years (mean ± standard deviation)) who were suitable for weaning with pressure support ventilation (PSV). For the PEEP wave, PEEP was elevated by 1 cmH2O after every fifth breath during PSV. This was repeated five times, until a total PEEP increase of 5 cmH2O was reached. Subsequently, PEEP was reduced in steps of 1 cmH2O in the same manner until the original PEEP level was reached. Crs was calculated using EIT from the global, ventral and dorsal lung regions of interest. For reference measurements, all patients were also examined during controlled mechanical ventilation (CMV) with a low-flow pressure-volume maneuver. Global and regional Crs(low-flow) was calculated as the slope of the pressure-volume loop between the pressure that corresponded to the selected PEEP and PEEP +5 cmH2O. For additional reference, Crs during CMV (Crs(CMV)) was calculated as expired tidal volume divided by the difference between airway plateau pressure and PEEP. Respiratory system compliance calculated from the PEEP wave (Crs(PEEP wave)) correlated closely with both reference measurements (r = 0.79 for Crs(low-flow) and r = 0.71 for Crs(CMV)). No significant difference was observed between the mean Crs(PEEP wave) and the mean Crs(low-flow). However, a significant bias of +17.1 ml/cmH2O was observed between Crs(PEEP wave) and Crs(CMV). Analyzing a PEEP wave

  20. Lung recruitment and positive end-expiratory pressure have different effects on CO2 elimination in healthy and sick lungs.

    PubMed

    Tusman, Gerardo; Bohm, Stephan H; Suarez-Sipmann, Fernando; Scandurra, Adriana; Hedenstierna, Göran

    2010-10-01

    We studied the effects that the lung recruitment maneuver (RM) and positive end-expiratory pressure (PEEP) have on the elimination of CO(2) per breath (Vtco(2,br)). In 7 healthy and 7 lung-lavaged pigs at constant ventilation, PEEP was increased from 0 to 18 cm H(2)O and then decreased to 0 in steps of 6 cm H(2)O every 10 minutes. Cycling RMs with plateau pressure/PEEP of 40/20 (healthy) and 50/25 (lavaged) cm H(2)O were applied for 2 minutes between 18-PEEP steps. Volumetric capnography, respiratory mechanics, blood gas, and hemodynamic data were recorded. In healthy lungs before the RM, Vtco(2,br) was inversely proportional to PEEP decreasing from 4.0 (3.6-4.4) mL (median and interquartile range) at 0-PEEP to 3.1 (2.8-3.4) mL at 18-PEEP (P < 0.05). After the RM, Vtco(2,br) increased from 3.3 (3-3.6) mL at 18-PEEP to 4.0 (3.5-4.5) mL at 0-PEEP (P < 0.05). In lavaged lungs before the RM, Vtco(2,br) increased initially from 2.0 (1.7-2.3) mL at 0-PEEP to 2.6 (2.2-3) mL at 12-PEEP (P < 0.05) but then decreased to 2.4 (2-2.8) mL when PEEP was increased further to 18 cm H(2)O (P < 0.05). After the RM, the highest Vtco(2,br) of 2.9 (2.1-3.7) mL was observed at 12-PEEP and then decreased to 2.5 (1.9-3.1) mL at 0-PEEP (P < 0.05). Vtco(2,br) was directly related to changes in lung perfusion, the area of gas exchange, and alveolar ventilation but inversely related to changes in dead space. CO(2) elimination by the lungs was dependent on PEEP and recruitment and showed major differences between healthy and lavaged lungs.

  1. Positive Expiratory Pressure Improves Oxygenation in Healthy Subjects Exposed to Hypoxia

    PubMed Central

    Nespoulet, Hugo; Rupp, Thomas; Bachasson, Damien; Tamisier, Renaud; Wuyam, Bernard; Lévy, Patrick; Verges, Samuel

    2013-01-01

    Introduction Positive end-expiratory pressure (PEEP) is commonly used in critical care medicine to improve gas exchange. Altitude sickness is associated with exaggerated reduction in arterial oxygenation. We assessed the effect of PEEP and pursed lips breathing (PLB) on arterial and tissue oxygenation under normobaric and hypobaric hypoxic conditions. Methods Sixteen healthy volunteers were exposed to acute normobaric hypoxia (Laboratory study, FiO2=0.12). The protocol consisted in 3-min phases with PEEPs of 0, 5 or 10 cmH2O, PLB or similar ventilation than with PEEP-10, interspaced with 3-min phases of free breathing. Arterial (pulse oximetry) and quadriceps (near-infrared spectroscopy) oxygenation, ventilation, cardiac function, esophageal and gastric pressures and subjects’ subjective perceptions were recorded continuously. In addition, the effect of PEEP on arterial oxygenation was tested at 4,350 m of altitude in 9 volunteers breathing for 20 min with PEEP-10 (Field study). Results During the laboratory study, PEEP-10 increased arterial and quadriceps oxygenation (arterial oxygen saturation +5.6±5.0% and quadriceps oxyhemoglobin +58±73 µmol.cm compared to free breathing; p<0.05). Conversely, PLB did not increase oxygenation. Oxygenation improvement with PEEP-10 was accompanied by an increase in expiratory esophageal and gastric pressures (esophageal pressure swing +5.4±3.2 cmH2O, p<0.05) but no change in minute ventilation, breathing pattern, end-tidal CO2 or cardiac function (all p>0.05) compared to PEEP-0. During the field study, PEEP-10 increased arterial oxygen saturation by +6.7±6.0% after the 3rd minute with PEEP-10 without further significant increase until the 20th minute with PEEP-10. Subjects did not report any significant discomfort with PEEP. Conclusions These data indicate that 10-cmH2O PEEP significantly improves arterial and muscle oxygenation under both normobaric and hypobaric hypoxic conditions in healthy subjects. PEEP-10 could be an

  2. Detection of ‘best’ positive end-expiratory pressure derived from electrical impedance tomography parameters during a decremental positive end-expiratory pressure trial

    PubMed Central

    2014-01-01

    Introduction This study compares different parameters derived from electrical impedance tomography (EIT) data to define ‘best’ positive end-expiratory pressure (PEEP) during a decremental PEEP trial in mechanically-ventilated patients. ‘Best’ PEEP is regarded as minimal lung collapse and overdistention in order to prevent ventilator-induced lung injury. Methods A decremental PEEP trial (from 15 to 0 cm H2O PEEP in 4 steps) was performed in 12 post-cardiac surgery patients on the ICU. At each PEEP step, EIT measurements were performed and from this data the following were calculated: tidal impedance variation (TIV), regional compliance, ventilation surface area (VSA), center of ventilation (COV), regional ventilation delay (RVD index), global inhomogeneity (GI index), and intratidal gas distribution. From the latter parameter we developed the ITV index as a new homogeneity parameter. The EIT parameters were compared with dynamic compliance and the PaO2/FiO2 ratio. Results Dynamic compliance and the PaO2/FiO2 ratio had the highest value at 10 and 15 cm H2O PEEP, respectively. TIV, regional compliance and VSA had a maximum value at 5 cm H2O PEEP for the non-dependent lung region and a maximal value at 15 cm H2O PEEP for the dependent lung region. GI index showed the lowest value at 10 cm H2O PEEP, whereas for COV and the RVD index this was at 15 cm H2O PEEP. The intratidal gas distribution showed an equal contribution of both lung regions at a specific PEEP level in each patient. Conclusion In post-cardiac surgery patients, the ITV index was comparable with dynamic compliance to indicate ‘best’ PEEP. The ITV index can visualize the PEEP level at which ventilation of the non-dependent region is diminished, indicating overdistention. Additional studies should test whether application of this specific PEEP level leads to better outcome and also confirm these results in patients with acute respiratory distress syndrome. PMID:24887391

  3. Impact of acute hypercapnia and augmented positive end-expiratory pressure on right ventricle function in severe acute respiratory distress syndrome

    PubMed Central

    Mekontso Dessap, Armand; Charron, Cyril; Devaquet, Jérôme; Aboab, Jérôme; Jardin, François; Brochard, Laurent; Vieillard-Baron, Antoine

    2009-01-01

    Purpose To evaluate the effects of acute hypercapnia induced by positive end-expiratory pressure (PEEP) variations at constant plateau pressure (Pplat) in patients with severe acute respiratory distress syndrome (ARDS) on right (R) and left ventricular (LV) function. Methods Prospective observational study in two academic intensive care units enrolling 11 adults with severe ARDS (PaO2/FiO2<150 mm Hg at PEEP >5 cm H2O). We compared three ventilatory strategies, each used for 1 hour, with Pplat at 22 [20–25] cm H2O: low PEEP (5.4 cm H2O) or high PEEP (11.0 cm H2O) with compensation of the tidal volume reduction by either a high respiratory rate (high PEEP/high rate) or instrumental dead space decrease (high PEEP/low rate). We assessed RV function (transesophageal echocardiography), alveolar dead space (expired CO2), and alveolar recruitment (pressure-volume curves). Results Compared to low PEEP, PaO2/FiO2 ratio and alveolar recruitment were increased with high PEEP. Alveolar dead space remained unchanged. Both high-PEEP strategies induced higher PaCO2 levels (71 [60–94] and 75 [53–84], vs. 52 [43–68] mm Hg) and lower pH values (7.17 [7.12–7.23] and 7.20 [7.16–7.25] vs. 7.30 [7.24–7.35]), as well as a significant decrease in cardiac index, RV dilatation and LV deformation. The decrease in stroke index tended to be negatively correlated to the increase in alveolar recruitment with high PEEP. Conclusions Acidosis and hypercapnia induced by tidal volume reduction and increase in PEEP at constant Pplat was associated with impaired RV function and hemodynamics despite a positive effect on oxygenation and alveolar recruitment. PMID:19652953

  4. Patient-controlled positive end-expiratory pressure with neuromuscular disease: effect on speech in patients with tracheostomy and mechanical ventilation support.

    PubMed

    Garguilo, Marine; Leroux, Karl; Lejaille, Michèle; Pascal, Sophie; Orlikowski, David; Lofaso, Frédéric; Prigent, Hélène

    2013-05-01

    Communication is a major issue for patients with tracheostomy who are supported by mechanical ventilation. The use of positive end-expiratory pressure (PEEP) may restore speech during expiration; however, the optimal PEEP level for speech may vary individually. We aimed to improve speech quality with an individually adjusted PEEP level delivered under the patient's control to ensure optimal respiratory comfort. Optimal PEEP level (PEEPeff), defined as the PEEP level that allows complete expiration through the upper airways, was determined for 12 patients with neuromuscular disease who are supported by mechanical ventilation. Speech and respiratory parameters were studied without PEEP, with PEEPeff, and for an intermediate PEEP level. Flow and airway pressure were measured. Microphone speech recordings were subjected to both quantitative and qualitative assessments of speech, including an intelligibility score, a perceptual score, and an evaluation of prosody determined by two speech therapists blinded to PEEP condition. Text reading time, phonation flow, use of the respiratory cycle for phonation, and speech comfort significantly improved with increasing PEEP, whereas qualitative parameters remained unchanged. This resulted mostly from the increase of the expiratory volume through the upper airways available for speech for all patients combined, with a rise in respiratory rate for nine patients. Respiratory comfort remained stable despite high levels of PEEPeff (median, 10.0 cm H2O; interquartile range, 9.5-12.0 cm H₂O). Patient-controlled PEEP allowed for the use of high levels of PEEP with good respiratory tolerance and significant improvement in speech (enabling phonation during the entire respiratory cycle in most patients). The device studied could be implemented in home ventilators to improve speech and, therefore, autonomy of patients with tracheostomy. ClinicalTrials.gov; No.: NCT01479959; URL: clinicaltrials.gov.

  5. Experimental ventilator-induced lung injury: exacerbation by positive end-expiratory pressure.

    PubMed

    Villar, Jesús; Herrera-Abreu, Maria Teresa; Valladares, Francisco; Muros, Mercedes; Pérez-Méndez, Lina; Flores, Carlos; Kacmarek, Robert M

    2009-06-01

    Previous experimental studies of ventilator-induced lung injury have shown that positive end-expiratory pressure (PEEP) is protective. The authors hypothesized that the application of PEEP during volume-controlled ventilation with a moderately high tidal volume (VT) in previously healthy in vivo rats does not attenuate ventilator-induced lung injury if the peak airway pressure markedly increases during the application of PEEP. Sixty healthy, male Sprague-Dawley rats were anesthetized and randomized to be mechanically ventilated for 4 h at (1) VT of 6 ml/kg, (2) VT of 20 ml/kg, or (3) VT of 20 ml/kg plus 10 cm H2O of PEEP. Peak airway pressures, gas exchange, histologic evaluation, mortality, total lung tissue cytokine gene expression, and serum cytokine concentrations were analyzed. Peak airway pressures exceeded 30 cm H2O with high VT plus PEEP. All lungs ventilated with high VT had perivascular edema and inflammatory infiltrates. In addition, those ventilated with PEEP had small hemorrhages foci. Five animals from the high VT plus PEEP group died (P = 0.020). Animals ventilated with high VT (with or without PEEP) had a substantial increase in serum interleukin-6 (P = 0.0002), and those ventilated with high VT plus PEEP had a 5.5-fold increase in systemic levels of tumor necrosis factor-alpha (P = 0.007). In contrast to previous reports, PEEP exacerbated lung damage and contributed to fatal outcome in an in vivo, mild overdistension model of ventilator-induced lung injury in previously healthy rats. That is, the addition of high PEEP to a constant large VT causes injury in previously healthy animals.

  6. The effects of positive expiratory pressure on isovolume flow and dynamic hyperinflation in patients receiving mechanical ventilation.

    PubMed

    Gay, P C; Rodarte, J R; Hubmayr, R D

    1989-03-01

    The use of continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) has been advocated by some to assist in the weaning process of patients receiving mechanical ventilation for respiratory failure. The efficacy of this technique and its effect on respiratory system mechanics are not well understood. The theoretical advantage of CPAP or PEEP during the weaning process can be obliterated if excessive dynamic hyperinflation is induced. A key determinant of the individual response to this proposed weaning technique is the recognition of the presence or absence of expiratory flow limitation. We studied the effect of progressively increased levels of applied PEEP on isovolume expiratory flow and end-expiratory lung volume in seven patients during controlled mechanical ventilation. In the absence of expiratory flow limitation, passive expiratory flow decreased and end-expiratory lung volume increased when any level of PEEP was applied. In contrast, flow-limited patients did not demonstrate a change in isovolume expiratory flow or end-expiratory lung volume until the applied PEEP reduced the driving pressure for expiratory flow below a critical value. All patients demonstrated dynamic hyperinflation during controlled ventilation as evident by the existence of intrinsic PEEP. The nominal value of applied PEEP that caused a reduction in isovolume expiratory flow was unrelated to the initial level of intrinsic PEEP. The clinical implications of these findings with respect to CPAP therapy during weaning from mechanical ventilation are discussed.

  7. Optimization of Positive End-Expiratory Pressure targeting the best arterial oxygen transport in the Acute Respiratory Distress Syndrome: the OPTIPEP study.

    PubMed

    Chimot, Loïc; Fedun, Yannick; Gacouin, Arnaud; Campillo, Boris; Marqué, Sophie; Gros, Antoine; Delour, Pierre; Bedon-Carte, Sandrine; Le Tulzo, Yves

    2016-12-13

    The optimal setting for positive end-expiratory pressure (PEEP) in mechanical ventilation remains controversial in the treatment of acute respiratory distress syndrome (ARDS). The aim of this study was to determine the optimum PEEP level in ARDS, which we defined as the level that allowed the best arterial oxygen delivery (DO2).We conducted a physiological multicenter prospective study on patients who suffering from ARDS according to standard definition and persistent after 6 hours of ventilation. The PEEP was set to 6 cmH2O at the beginning of the test and then was increased by 2 cmH2O after at least 15 min of being stabilized until the plateau pressure achieved 30 cmH2O. At each step, the cardiac output was measured by trans-esophageal echocardiography and gas blood was sampled.We were able to determine the optimal PEEP for twelve patients. The ratio of PaO2/FiO2 at inclusion was 131±40 with a mean FiO2 of 71±3%. The optimal PEEP level was lower than the higher PEEP despite a constant increase in SaO2. The optimal PEEP levels varied between 8 and 18 cmH2O.Our results show that in ARDS patients the optimal PEEP differs between each patient and require being determined with monitoring.

  8. Short-term effects of positive end-expiratory pressure on breathing pattern: an interventional study in adult intensive care patients

    PubMed Central

    Haberthür, Christoph; Guttmann, Josef

    2005-01-01

    Introduction Positive end-expiratory pressure (PEEP) is used in mechanically ventilated patients to increase pulmonary volume and improve gas exchange. However, in clinical practice and with respect to adult, ventilator-dependent patients, little is known about the short-term effects of PEEP on breathing patterns. Methods In 30 tracheally intubated, spontaneously breathing patients, we sequentially applied PEEP to the trachea at 0, 5 and 10 cmH2O, and then again at 5 cmH2O for 30 s each, using the automatic tube compensation mode. Results Increases in PEEP were strongly associated with drops in minute ventilation (P < 0.0001) and respiratory rate (P < 0.0001). For respiratory rate, a 1 cmH2O change in PEEP in either direction resulted in a change in rate of 0.4 breaths/min. The effects were exclusively due to changes in expiratory time. Effects began to manifest during the first breath and became fully established in the second breath for each PEEP level. Identical responses were found when PEEP levels were applied for 10 or 60 s. Post hoc analysis revealed a similar but stronger response in patients with impaired respiratory system compliance. Conclusion In tracheally intubated, spontaneously breathing adult patients, the level of PEEP significantly influences the resting short-term breathing pattern by selectively affecting expiratory time. These findings are best explained by the Hering–Breuer inflation/deflation reflex. PMID:16137354

  9. High or conventional positive end-expiratory pressure in adult respiratory distress syndrome.

    PubMed

    Díaz-Alersi, R; Navarro-Ramírez, C

    2014-01-01

    Patients with acute respiratory distress syndrome may require high positive end-expiratory pressure (PEEP) levels, though the optimum level remains to be established. Several clinical trials have compared high PEEP levels versus conventional PEEP. Overall, although high PEEP levels improve oxygenation and are safe, they do not result in a significant reduction of the mortality rates. Nevertheless, some metaanalyses have revealed 2 situations in which high PEEP may decrease mortality: When used in severe distress and when PEEP is set following the characteristics of lung mechanics. Five studies have explored this latter scenario. Unfortunately, all of them have small sample sizes and have used different means to determine optimum PEEP. It is therefore necessary to conduct studies of sufficient sample size to compare the treatment of patients with severe acute respiratory distress syndrome, using a protective ventilation strategy with high PEEP guided by the characteristics of lung mechanics and ventilation with the protocol proposed by the ARDS Network. Copyright © 2013 Elsevier España, S.L. and SEMICYUC. All rights reserved.

  10. Paradoxical responses to positive end-expiratory pressure in patients with airway obstruction during controlled ventilation*

    PubMed Central

    Caramez, Maria Paula; Borges, Joao B.; Tucci, Mauro R.; Okamoto, Valdelis N.; Carvalho, Carlos R. R.; Kacmarek, Robert M.; Malhotra, Atul; Velasco, Irineu Tadeu; Amato, Marcelo B. P.

    2008-01-01

    Objective To reevaluate the clinical impact of external positive end-expiratory pressure (external-PEEP) application in patients with severe airway obstruction during controlled mechanical ventilation. The controversial occurrence of a paradoxic lung deflation promoted by PEEP was scrutinized. Design External-PEEP was applied stepwise (2 cm H2O, 5-min steps) from zero-PEEP to 150% of intrinsic-PEEP in patients already submitted to ventilatory settings minimizing overinflation. Two commonly used frequencies during permissive hypercapnia (6 and 9/min), combined with two different tidal volumes (VT: 6 and 9 mL/kg), were tested. Setting A hospital intensive care unit. Patients Eight patients were enrolled after confirmation of an obstructive lung disease (inspiratory resistance, >20 cm H2O/L per sec) and the presence of intrinsic-PEEP (≥5 cm H2O) despite the use of very low minute ventilation. Interventions All patients were continuously monitored for intra-arterial blood gas values, cardiac output, lung mechanics, and lung volume with plethysmography. Measurements and Main Results Three different responses to external-PEEP were observed, which were independent of ventilatory settings. In the biphasic response, isovolume-expiratory flows and lung volumes remained constant during progressive PEEP steps until a threshold, beyond which overinflation ensued. In the classic overinflation response, any increment of external-PEEP caused a decrease in isovolume-expiratory flows, with evident overinflation. In the paradoxic response, a drop in functional residual capacity during external-PEEP application (when compared to zero-external-PEEP) was commonly accompanied by decreased plateau pressures and total-PEEP, with increased isovolume-expiratory flows. The paradoxic response was observed in five of the eight patients (three with asthma and two with chronic obstructive pulmonary disease) during at least one ventilator pattern. Conclusions External-PEEP application may

  11. Abdominal compartment syndrome and acute kidney injury due to excessive auto-positive end-expiratory pressure.

    PubMed

    Matthew, Dwight; Oxman, David; Djekidel, Karim; Ahmed, Ziauddin; Sherman, Michael

    2013-02-01

    Abdominal compartment syndrome is an under-recognized cause of acute kidney injury in critically ill patients. We report a case of a patient with severe obstructive lung disease who, while intubated for respiratory failure, developed abdominal compartment syndrome and oliguric acute kidney injury due to air-trapping and excessive auto-positive end-expiratory pressure (auto-PEEP; also known as intrinsic PEEP). When chemical paralysis was initiated and the auto-PEEP resolved, the patient's intra-abdominal hypertension rapidly improved and kidney function recovered immediately. Abdominal compartment syndrome secondary to excessive auto-PEEP appears to be unreported in the literature; however, any process that significantly increases intrathoracic pressure conceivably could cause increased pressure to be transmitted to the abdominal compartment, resulting in organ failure. Patients undergoing mechanical ventilation, which puts them at risk of airflow obstruction and the development of intra-abdominal hypertension, should be evaluated for air-trapping and excessive auto-PEEP.

  12. The effect of positive end expiratory pressure on the respiratory profile during one-lung ventilation for thoracotomy.

    PubMed

    Leong, L M C; Chatterjee, S; Gao, F

    2007-01-01

    Summary In this randomised controlled trial we examined the effects of four different levels of positive end expiratory pressure (PEEP at 0, 5, 8 or 10 cmH(2)O), added to the dependent lung, on respiratory profile and oxygenation during one lung ventilation. Forty-six patients were recruited to receive one of the randomised PEEP levels during one lung ventilation. We did not find significant differences in lung compliance, intra-operative or postoperative oxygenation amongst the four different groups. However, the physiological deadspace to tidal volume ventilation ratio was significantly lower in the 8 cmH(2)O PEEP group compared with the other levels of PEEP (p < 0.0001). We concluded that the use of PEEP (< or =10 cmH(2)O) during one lung ventilation does not clinically improve lung compliance, intra-operative or postoperative oxygenation despite a statistically significant reduction in the physiological deadspace to tidal volume ratio.

  13. Positive end-expiratory pressure may alter breathing cardiovascular variability and baroreflex gain in mechanically ventilated patients.

    PubMed

    Van de Louw, Andry; Médigue, Claire; Papelier, Yves; Cottin, François

    2010-04-19

    Baroreflex allows to reduce sudden rises or falls of arterial pressure through parallel RR interval fluctuations induced by autonomic nervous system. During spontaneous breathing, the application of positive end-expiratory pressure (PEEP) may affect the autonomic nervous system, as suggested by changes in baroreflex efficiency and RR variability. During mechanical ventilation, some patients have stable cardiorespiratory phase difference and high-frequency amplitude of RR variability (HF-RR amplitude) over time and others do not. Our first hypothesis was that a steady pattern could be associated with reduced baroreflex sensitivity and HF-RR amplitude, reflecting a blunted autonomic nervous function. Our second hypothesis was that PEEP, widely used in critical care patients, could affect their autonomic function, promoting both steady pattern and reduced baroreflex sensitivity. We tested the effect of increasing PEEP from 5 to 10 cm H2O on the breathing variability of arterial pressure and RR intervals, and on the baroreflex. Invasive arterial pressure, ECG and ventilatory flow were recorded in 23 mechanically ventilated patients during 15 minutes for both PEEP levels. HF amplitude of RR and systolic blood pressure (SBP) time series and HF phase differences between RR, SBP and ventilatory signals were continuously computed by complex demodulation. Cross-spectral analysis was used to assess the coherence and gain functions between RR and SBP, yielding baroreflex-sensitivity indices. At PEEP 10, the 12 patients with a stable pattern had lower baroreflex gain and HF-RR amplitude of variability than the 11 other patients. Increasing PEEP was generally associated with a decreased baroreflex gain and a greater stability of HF-RR amplitude and cardiorespiratory phase difference. Four patients who exhibited a variable pattern at PEEP 5 became stable at PEEP 10. At PEEP 10, a stable pattern was associated with higher organ failure score and catecholamine dosage. During

  14. Pulmonary acute respiratory distress syndrome: positive end-expiratory pressure titration needs stress index.

    PubMed

    Huang, Yingzi; Yang, Yi; Chen, Qiuhua; Liu, Songqiao; Liu, Ling; Pan, Chun; Yang, Congshan; Qiu, Haibo

    2013-11-01

    The heterogeneity of lung injury in pulmonary acute respiratory distress syndrome (ARDS) may have contributed to the greater response of hyperinflated area with positive end-expiratory pressure (PEEP). PEEP titrated by stress index can reduce the risk of alveolar hyperinflation in patients with pulmonary ARDS. The authors sought to investigate the effects of PEEP titrated by stress index on lung recruitment and protection after recruitment maneuver (RM) in pulmonary ARDS patients. Thirty patients with pulmonary ARDS were enrolled. After RM, PEEP was randomly set according to stress index, oxygenation, static pulmonary compliance (Cst), or lower inflection point (LIP) + 2 cmH2O strategies. Recruitment volume, gas exchange, respiratory mechanics, and hemodynamic parameters were collected. PEEP titrated by stress index (15.1 ± 1.8 cmH2O) was similar to the levels titrated by oxygenation (14.5 ± 2.9 cmH2O), higher than that titrated by Cst (11.3 ± 2.5 cmH2O) and LIP (12.9 ± 1.6 cmH2O) (P < 0.05). Compared with baseline, PaO2/FiO2 and recruitment volume were significantly improved after PEEP titration with the four strategies (P < 0.05). PaO2/FiO2 and recruitment volume were similar when using PEEP titrated by stress index and oxygenation but higher than that titrated by Cst and LIP. Compared with baseline, lung compliance increased significantly when PEEP determined by Cst, but there was no difference of Cst in these four strategies. There was no influence of PEEP titration with the four strategies on hemodynamic parameters. PEEP titration by stress index might be more beneficial for pulmonary ARDS patients after RM. Copyright © 2013 Elsevier Inc. All rights reserved.

  15. [Effect of using several levels of positive end-expiratory pressure over barotrauma's induced lung injury in a model of isolated and perfused rabbit lungs].

    PubMed

    Trejo, Humberto; Urich, Daniela; Pezzulo, Alejandro; Novoa, Eva; Marcano, Héctor; Crespo, Astrid; Sánchez de León, Roberto

    2006-03-01

    The use of Positive end-expiratory pressure (PEEP) as a strategy of mechanical ventilation offers its advantages, such as improved oxygenation, without causing alveolar overstretching and barotrauma. We aim to investigate the effect of several levels of PEEP on barotrauma and, whether an optimal level of PEEP exists. Forty-eight New Zealand rabbits (2.5-3.5 kg) were divided into four groups with PEEP settings of 0, 4, 8 and 12 cmH2O, at increasing levels of inspiratory volume (IV). This was done in blood perfused rabbit lungs and in lungs perfused with a Buffer-Albumin Solution. We observed that lungs ventilated with PEEP 0 cmH2O suffered pulmonary rupture at high IV (300cc), with significant increases of Pap (Pulmonary artery pressure) and FFR (Fluid filtration rate). Lungs ventilated with PEEP 8 and 12 suffered pulmonary rupture at lower IV (200cc and 150cc vs. 300cc respectively) On the other hand, lungs ventilated with PEEP 4 cmH2O reached the highest IV (400cc), in addition, they showed the lowest elevations of Pap and FFR. The acellular lungs ventilated with PEEP 4, 8 and 12 showed pulmonary rupture at lower IV when compared with cellular ones (300cc vs. 400cc: 100cc vs. 200cc and 100cc vs. 150cc respectively). We concluded that an optimal PEEP exists, which protects against barotrauma, however, excess of PEEP could enhance its development. The blood could contain some mediators which attenuate the damage induced by barotrauma.

  16. Airway mechanosensor behavior during application of positive end-expiratory pressure.

    PubMed

    Guardiola, Juan; Moffett, Bryan; Li, Huafeng; Punnakkattu, Rajeesh; Moldoveanu, Bogden; Liu, Jun; Du, Lei; Yu, Jerry

    2014-01-01

    Positive end-expiratory pressure (PEEP) is commonly used in clinical settings. It is expected to affect the input from slowly adapting pulmonary stretch receptors (SARs), leading to altered cardiopulmonary functions. However, we know little about how SARs behave during PEEP application. Our study aimed to characterize the behavior of SARs during PEEP application. We recorded single-unit activities from 18 SARs in the cervical vagus nerve and examined their response to an increase of PEEP from 3 to 10 cm H2O for 20 min in anesthetized, open-chest and mechanically ventilated rabbits. The mean activity of the units increased immediately from 35.7 to 80.5 impulses per second at the fifth breath after increasing PEEP (n = 14, p < 0.001) and then gradually returned to 56.5 impulses per second at the end of 20 min of PEEP application (p < 0.001). In the meantime, peak airway pressure increased from 9.3 to 32.7 cm H2O, and then gradually returned to 29.4 cm H2O (n = 18; p < 0.05) after 20 min. The remaining four units ceased firing at 34.7 s (range 10-56 s) after their initial increased activity upon 10 cm H2O PEEP application. The unit activity resumed as the PEEP was returned to 3 cm H2O. High PEEP stimulates SARs and SAR activity gradually returns towards the baseline via multiple mechanisms including receptor deactivation, neural habituation and mechanical adaptation. Understanding of the sensory inputs during PEEP application will assist in developing better strategies of mechanical ventilation.

  17. Maintenance of end-expiratory recruitment with increased respiratory rate after saline-lavage lung injury.

    PubMed

    Syring, Rebecca S; Otto, Cynthia M; Spivack, Rebecca E; Markstaller, Klaus; Baumgardner, James E

    2007-01-01

    Cyclical recruitment of atelectasis with each breath is thought to contribute to ventilator-associated lung injury. Extrinsic positive end-expiratory pressure (PEEPe) can maintain alveolar recruitment at end exhalation, but PEEPe depresses cardiac output and increases overdistension. Short exhalation times can also maintain end-expiratory recruitment, but if the mechanism of this recruitment is generation of intrinsic PEEP (PEEPi), there would be little advantage compared with PEEPe. In seven New Zealand White rabbits, we compared recruitment from increased respiratory rate (RR) to recruitment from increased PEEPe after saline lavage. Rabbits were ventilated in pressure control mode with a fraction of inspired O(2) (Fi(O(2))) of 1.0, inspiratory-to-expiratory ratio of 2:1, and plateau pressure of 28 cmH(2)O, and either 1) high RR (24) and low PEEPe (3.5) or 2) low RR (7) and high PEEPe (14). We assessed cyclical lung recruitment with a fast arterial Po(2) probe, and we assessed average recruitment with blood gas data. We measured PEEPi, cardiac output, and mixed venous saturation at each ventilator setting. Recruitment achieved by increased RR and short exhalation time was nearly equivalent to recruitment achieved by increased PEEPe. The short exhalation time at increased RR, however, did not generate PEEPi. Cardiac output was increased on average 13% in the high RR group compared with the high PEEPe group (P < 0.001), and mixed venous saturation was consistently greater in the high RR group (P < 0.001). Prevention of end-expiratory derecruitment without increased end-expiratory pressure suggests that another mechanism, distinct from intrinsic PEEP, plays a role in the dynamic behavior of atelectasis.

  18. 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

  19. Dynamic functional residual capacity can be estimated using a stress-strain approach.

    PubMed

    Sundaresan, Ashwath; Geoffrey Chase, J; Hann, Christopher E; Shaw, Geoffrey M

    2011-02-01

    Acute Respiratory Distress Syndrome (ARDS) results in collapse of alveolar units and loss of lung volume at the end of expiration. Mechanical ventilation is used to treat patients with ARDS or Acute Lung Injury (ALI), with the end objective being to increase the dynamic functional residual capacity (dFRC), and thus increasing overall functional residual capacity (FRC). Simple methods to estimate dFRC at a given positive end expiratory pressure (PEEP) level in patients with ARDS/ALI currently does not exist. Current viable methods are time-consuming and relatively invasive. Previous studies have found a constant linear relationship between the global stress and strain in the lung independent of lung condition. This study utilizes the constant stress-strain ratio and an individual patient's volume responsiveness to PEEP to estimate dFRC at any level of PEEP. The estimation model identifies two global parameters to estimate a patient specific dFRC, β and mβ. The parameter β captures physiological parameters of FRC, lung and respiratory elastance and varies depending on the PEEP level used, and mβ is the gradient of β vs. PEEP. dFRC was estimated at different PEEP values and compared to the measured dFRC using retrospective data from 12 different patients with different levels of lung injury. The median percentage error is 18% (IQR: 6.49) for PEEP=5 cmH₂O, 10% (IQR: 9.18) for PEEP=7 cmH₂O, 28% (IQR: 12.33) for PEEP=10 cmH₂O, 3% (IQR: 2.10) for PEEP=12 cmH₂O and 10% (IQR: 9.11) for PEEP=15 cmH₂O. The results were further validated using a cross-correlation (N=100,000). Linear regression between the estimated and measured dFRC with a median R² of 0.948 (IQR: 0.915, 0.968; 90% CI: 0.814, 0.984) over the N=100,000 cross-validation tests. The results suggest that a model based approach to estimating dFRC may be viable in a clinical scenario without any interruption to ventilation and can thus provide an alternative to measuring dFRC by disconnecting the

  20. Blood gases and pulmonary blood flow during resuscitation of very preterm lambs treated with antenatal betamethasone and/or Curosurf: effect of positive end-expiratory pressure.

    PubMed

    Crossley, Kelly J; Morley, Colin J; Allison, Beth J; Polglase, Graeme R; Dargaville, Peter A; Harding, Richard; Hooper, Stuart B

    2007-07-01

    Resuscitation of very premature lambs with positive end-expiratory pressure (PEEP) improves oxygenation and reduces pulmonary blood flow (PBF). However, the effects of PEEP on blood gases and PBF have not been studied in preterm lambs receiving antenatal corticosteroids or postnatal surfactant. Lambs were delivered at 125 d of gestation (term 147 d) and ventilated with a tidal volume (VT) of 5 mL/kg using different levels of PEEP. Four treatment groups were studied: (1) antenatal betamethasone 24 and 36 h before delivery; (2) postnatal Curosurf; (3) antenatal betamethasone and postnatal Curosurf; (4) untreated controls. Blood gases, PBF, and ventilator parameters were recorded during the first 2 h. Increasing PEEP improved oxygenation even after antenatal betamethasone and postnatal Curosurf, without adverse effects on arterial PCO2. Increasing PEEP reduced PBF; this effect was not altered by betamethasone and/or Curosurf. In very preterm lambs ventilated with fixed VT, increasing levels of PEEP improved oxygenation after antenatal glucocorticoids and/or postnatal surfactant. These treatments do not alter the deleterious effects of high levels of PEEP on PBF.

  1. Low positive end-expiratory pressure does not exacerbate nebulized-acid lung injury in dogs.

    PubMed

    Pellett, Andrew A; Welsh, David A; deBoisblanc, Bennett P; Lipscomb, Gary; Johnson, Royce W; Lord, Kevin C; Levitzky, Michael G

    2005-03-01

    It is not clear if low end-expiratory pressures contribute to ventilator-induced lung injury in large animals. We sought to determine whether ventilation with a low level of positive end-expiratory pressure (PEEP) worsens preexisting permeability lung injury in dogs. Lung injury was initiated in 20 mongrel dogs by ventilating with nebulized 3N hydrochloric acid until a lower inflection point (LIP) appeared on the respiratory system pressure-volume loop. One group of 10 dogs was then ventilated for 4 hours with PEEP set below the LIP (low PEEP), whereas the remaining group of dogs was ventilated for the same time period with similar tidal volumes but with PEEP set above the LIP (high PEEP). We found histologic evidence of reduced alveolar volumes in the low-PEEP animals. However, there were no differences in neutrophil infiltration, lung lobe weights, pulmonary capillary hemorrhage or congestion, or arterial endothelin-1 concentration between the 2 protocol groups. In conclusion, we were unable to demonstrate that ventilation with PEEP set below the LIP exacerbates hydrochloric acid-induced lung injury in dogs.

  2. Intraoperative ventilation strategies to prevent postoperative pulmonary complications: Systematic review, meta-analysis, and trial sequential analysis.

    PubMed

    Serpa Neto, Ary; Schultz, Marcus J; Gama de Abreu, Marcelo

    2015-09-01

    For many years, mechanical ventilation with high tidal volumes (V(T)) was common practice in operating theaters because this strategy recruits collapsed lung tissue, improves ventilation-perfusion mismatch, and thus decreases the need for high oxygen fractions. Positive end-expiratory pressure (PEEP) was seldom used because it could cause cardiac compromise. Increasing advances in the understanding of the mechanisms of ventilator-induced lung injury from animal studies and randomized controlled trials in patients with uninjured lungs in intensive care unit and operation room have pushed anesthesiologists to consider lung-protective strategies during intraoperative ventilation. These strategies at least include the use of low V(T), and perhaps also the use of PEEP, which when compared to high V(T) with low PEEP may prevent the occurrence of postoperative pulmonary complications (PPCs). Such protective effects, however, are likely ascribed to low V(T) rather than to PEEP. In fact, at least in nonobese patients undergoing open abdominal surgery, high PEEP does not protect against PPCs, and it can impair the hemodynamics. Further studies shall determine whether a strategy consisting of low V(T) combined with PEEP and recruitment maneuvers reduces PPCs in obese patients and other types of surgery (e.g., laparoscopic and thoracic), compared to low V(T) with low PEEP. Furthermore, the role of driving pressure for titrating ventilation settings in patients with uninjured lungs shall be investigated.

  3. Peripheral pulmonary atelectasis and oxygentation impairment following coronary artery bypass grafting.

    PubMed

    Ishikawa, S; Takahashi, T; Ohtaki, A; Sato, Y; Suzuki, M; Hasegawa, Y; Ohki, S; Mohara, J; Oshima, K; Morishita, Y

    2002-08-01

    Severe pulmonary oxygenation impairment occurred in some patients with pleurotomy during the harvest of the internal mammary artery graft followed by coronary artery bypass grafting (CABG). Peripheral pulmonary atelectasis in the postoperative chest X-ray was detected in these patients. We studied the efficacy of intraoperative positive end-expiratory airway pressure (PEEP) therapy for the prevention of postoperative pulmonary oxygenation impairment. The pleural cavity was intraoperatively opened in 40 patients with solitary CABG procedure performed during 5 years since January 1992. These patients were divided into two groups. Intraoperative PEEP therapy, which is initiated just after pleurotomy, was not used in 32 patients before May, 1996 (control group) and used for recent 8 patients with pleurotomy (PEEP group). The mean age of patients was 60 years old in the control group and 68 in the PEEP group. Respiratory insufficiency (A-aDO2 >400 mmHg and RI >1.5) was detected in 6 patients in the control group. Three out of these 6 patients required long-term mechanical respiratory support over a week. No respiratory insufficiency occurred in patients of the PEEP group. Values of PaO2, A-aDO2, respiratory index and shunt ratio were significantly worse in the control group than in the PEEP group. In conclusion, PEEP therapy may prevent pulmonary atelectasis and oxygen impairment after CABG.

  4. Cardiac output estimation using pulmonary mechanics in mechanically ventilated patients

    PubMed Central

    2010-01-01

    The application of positive end expiratory pressure (PEEP) in mechanically ventilated (MV) patients with acute respiratory distress syndrome (ARDS) decreases cardiac output (CO). Accurate measurement of CO is highly invasive and is not ideal for all MV critically ill patients. However, the link between the PEEP used in MV, and CO provides an opportunity to assess CO via MV therapy and other existing measurements, creating a CO measure without further invasiveness. This paper examines combining models of diffusion resistance and lung mechanics, to help predict CO changes due to PEEP. The CO estimator uses an initial measurement of pulmonary shunt, and estimations of shunt changes due to PEEP to predict CO at different levels of PEEP. Inputs to the cardiac model are the PV loops from the ventilator, as well as the oxygen saturation values using known respiratory inspired oxygen content. The outputs are estimates of pulmonary shunt and CO changes due to changes in applied PEEP. Data from two published studies are used to assess and initially validate this model. The model shows the effect on oxygenation due to decreased CO and decreased shunt, resulting from increased PEEP. It concludes that there is a trade off on oxygenation parameters. More clinically importantly, the model also examines how the rate of CO drop with increased PEEP can be used as a method to determine optimal PEEP, which may be used to optimise MV therapy with respect to the gas exchange achieved, as well as accounting for the impact on the cardiovascular system and its management. PMID:21108836

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

    PubMed Central

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

    2014-01-01

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

  6. Electrical impedance tomography monitoring in acute respiratory distress syndrome patients with mechanical ventilation during prolonged positive end-expiratory pressure adjustments.

    PubMed

    Hsu, Chia-Fu; Cheng, Jen-Suo; Lin, Wei-Chi; Ko, Yen-Fen; Cheng, Kuo-Sheng; Lin, Sheng-Hsiang; Chen, Chang-Wen

    2016-03-01

    The time required to reach oxygenation equilibrium after positive end-expiratory pressure (PEEP) adjustments in mechanically ventilated patients with acute respiratory distress syndrome (ARDS) is unclear. We used electrical impedance tomography to elucidate gas distribution and factors related to oxygenation status following PEEP in patients with ARDS. Nineteen mechanically ventilated ARDS patients were placed on baseline PEEP (PEEPB) for 1 hour, PEEPB - 4 cmH2O PEEP (PEEPL) for 30 minutes, and PEEPB + 4 cmH2O PEEP (PEEPH) for 1 hour. Tidal volume and respiratory rate were similar. Impedance changes, respiratory parameters, and arterial blood gases were measured at baseline, 5 minutes, and 30 minutes after PEEPL, and 5 minutes, 15 minutes, 30 minutes, and 1 hour after PEEPH. PaO2/fraction of inspired oxygen (P/F ratio) decreased quickly from PEEPB to PEEPL, and stabilized 5 minutes after PEEPL. However the P/F ratio progressively increased from PEEPL to PEEPH, and a significantly higher P/F ratio and end-expiratory lung impedance were found at 60 minutes compared to 5 minutes after PEEPH. The end-expiratory lung impedance level significantly correlated with P/F ratio (p < 0.001). With increasing PEEP, dorsal ventilation significantly increased; however, regional ventilation did not change over time with PEEP level. Late improvements in oxygenation following PEEP escalation are probably due to slow recruitment in ventilated ARDS patients. Electrical impedance tomography may be an appropriate tool to assess recruitment and oxygenation status in patients with changes in PEEP. Copyright © 2015. Published by Elsevier B.V.

  7. Effects of positive end-expiratory pressure and 30% inspired oxygen on pulmonary mechanics and atelectasis in cats undergoing non-bronchoscopic bronchoalveolar lavage.

    PubMed

    Bernhard, Christa; Masseau, Isabelle; Dodam, John; Outi, Hilton; Krumme, Stacy; Bishop, Kaitlin; Graham, Amber; Reinero, Carol

    2017-06-01

    Objectives The objective of this study was to determine if modification of inspired oxygen concentration or positive end-expiratory pressure (PEEP) would alter bronchoalveolar lavage (BAL)-induced changes in pulmonary mechanics or atelectasis, as measured using ventilator-acquired pulmonary mechanics and thoracic CT. Methods Six experimentally asthmatic cats underwent anesthesia and non-bronchoscopic BAL, each under four randomized treatment conditions: 100% oxygen, zero PEEP; 30% oxygen, zero PEEP; 100% oxygen, PEEP 2 cmH2O; and 30% oxygen, PEEP 2 cmH2O. Pulse oximetry was used to estimate oxygen saturation (SpO2). Ventilator-acquired pulmonary mechanics and thoracic CT scans were collected prior to BAL and at 1, 5 and 15 mins post-BAL. Results While receiving 100% oxygen, no cat had SpO2 <91%. Some cats receiving 30% oxygen had decreased saturation immediately post-BAL (mean ± SD 70.8 ± 31%), but 6/8 of these had SpO2 >90% by 1 min later. There was a significant increase in airway resistance and a decrease in lung compliance following BAL, but there was no significant difference between treatment groups. Cats receiving no PEEP and 30% oxygen conserved better aeration of the lung parenchyma in BAL-sampled areas than those receiving no PEEP and 100% oxygen. Conclusions and relevance Alterations in pulmonary mechanics or atelectasis may not be reflected by SpO2 following BAL. The use of 30% inspired oxygen concentration failed to show any significant improvement in pulmonary mechanics but did diminish atelectasis. In some cats, it was also associated with desaturation of hemoglobin. The use of PEEP in this study did not show any effect on our outcome parameters. Further studies using higher PEEP (5-10 cmH2O) and intermediate inspired oxygen concentration (40-60%) are warranted to determine if they would confer clinical benefit in cats undergoing diagnostic BAL.

  8. Prevention of atelectasis formation during the induction of general anesthesia in morbidly obese patients.

    PubMed

    Coussa, Marta; Proietti, Stefania; Schnyder, Pierre; Frascarolo, Philippe; Suter, Michel; Spahn, Donat R; Magnusson, Lennart

    2004-05-01

    Atelectasis caused by general anesthesia is increased in morbidly obese patients. We have shown that application of positive end-expiratory pressure (PEEP) during the induction of anesthesia prevents atelectasis formation in nonobese patients. We therefore studied the efficacy of PEEP in morbidly obese patients to prevent atelectasis. Twenty-three adult morbidly obese patients (body mass index >35 kg/m(2)) were randomly assigned to one of two groups. In the PEEP group, patients breathed 100% oxygen (5 min) with a continuous positive airway pressure of 10 cm H(2)O and, after the induction, mechanical ventilation via a face mask with a PEEP of 10 cm H(2)O. In the control group, the same induction was applied but without continuous positive airway pressure or PEEP. Atelectasis, determined by computed tomography, and blood gas analysis were measured twice: before the induction and directly after intubation. After endotracheal intubation, patients of the control group showed an increase in the amount of atelectasis, which was much larger than in the PEEP group (10.4% +/- 4.8% in control group versus 1.7% +/- 1.3% in PEEP group; P < 0.001). After intubation with a fraction of inspired oxygen of 1.0, PaO(2) was significantly higher in the PEEP group compared with the control group (457 +/- 130 mm Hg versus 315 +/- 100 mm Hg, respectively; P = 0.035) We conclude that in morbidly obese patients, atelectasis formation is largely prevented by PEEP applied during the anesthetic induction and is associated with a better oxygenation. Application of positive end-expiratory pressure during induction of general anesthesia in morbidly obese patients prevents atelectasis formation and improves oxygenation. Therefore, this technique should be considered for anesthesia induction in morbidly obese patients.

  9. [The value of nitrogen washout/washin method in assessing alveolar recruitment volume in acute lung injury patients].

    PubMed

    Li, Yang; Tang, Rui; Huang, Ying-Zi; Zhang, Yun-Hang; Mao, Zi-Ruo; Pan, Chun; Liu, Song-Qiao; Guo, Feng-Mei; Yang, Yi; Qiu, Hai-Bo

    2013-04-01

    To evaluate the precision and feasibility of nitrogen washout/washin method in assessing lung recruitment of acute lung injury (ALI) patients. Fifteen ALI patients underwent mechanical ventilation were involved. Two positive end-expiratory pressure (PEEP) levels (high and low) were adjusted according to ARDSnet recommendations or measurement of transpulmonary pressure, each for 30 minutes. Tidal volume (Vt), plateau of airway pressure (Pplat), other respiratory mechanics, gas-exchange and hemodynamics were measured. End expiration lung volume (EELV) was measured at different PEEP levels through nitrogen washout/washin method, and formula (EELVhighPEEP-EELVlowPEEP)-VtlowPEEP/(PplatlowPEEP-PEEPlowPEEP)×(PEEPhigh-PEEPlow) was used as recruitment (Rec-N2). Alveolar recruitment was measured using pressure-volume (P-V) curves (Rec-mes). Correlation and consistency of Rec-N2 and Rec-mes were compared by correlation analysis and Bland-Altman technique. PEEP titrated by ARDSnet recommendations or transpulmonary pressure were (7 ± 2) cm H2O (1 cm H2O = 0.098 kPa) vs (14 ± 5) cm H2O (P = 0.008); and there were significant differences in peak pressure (23 ± 5) cm H2O vs (28 ± 6) cm H2O, plateau of airway pressure (17 ± 4)cm H2O vs (22 ± 6) cm H2O, esophageal pressure, transpulmonary pressure and other respiratory mechanics between the two PEEP levels (P < 0.05). The P-V curve technique gave Rec-mes a value of 100 (-25 ∼ 185)ml. The nitrogen washout/washin technique gave Rec-N2 a value of 180 (-19 ∼ 255) ml, which showed a good correlation with a bias of 46 (8 ∼ 80) ml (R(2) = 0.755, P < 0.0001). Nitrogen washout/washin technique can be used to determine lung recruitment volume of ALI patients.

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

    PubMed

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

    2016-03-09

    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.

  11. 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

  12. Effects of positive end-expiratory pressure on anesthesia-induced atelectasis and gas exchange in anesthetized and mechanically ventilated sheep.

    PubMed

    Staffieri, Francesco; Driessen, Bernd; Monte, Valentina De; Grasso, Salvatore; Crovace, Antonio

    2010-08-01

    To evaluate the effects of 10 cm H(2)O of positive end-expiratory pressure (PEEP) on lung aeration and gas exchange in mechanically ventilated sheep during general anesthesia induced and maintained with propofol. 10 healthy adult Bergamasca sheep. Sheep were sedated with diazepam (0.4 mg/kg, IV). Anesthesia was induced with propofol (5 mg/kg, IV) and maintained with propofol via constant rate infusion (0.4 mg/kg/min). Muscular paralysis was induced by administration of vecuronium (25 microg/kg, bolus IV) to facilitate mechanical ventilation. After intubation, sheep were positioned in right lateral recumbency and mechanically ventilated with pure oxygen and zero end-expiratory pressure (ZEEP). After 60 minutes, 10 cm H(2)O of PEEP was applied for 20 minutes. Spiral computed tomography of the thorax was performed, and data were recorded for hemodynamic and gas exchange variables and indicators of respiratory mechanics after 15 (T(15)), 30 (T(30)), and 60 (T(60)) minutes of ZEEP and after 20 minutes of PEEP (T(PEEP)). Computed tomography images were analyzed to determine the extent of atelectasis before and after PEEP application. At T(PEEP), the volume of poorly aerated and atelectatic compartments was significantly smaller than at T(15), T(30), and T(60), which indicated that there was PEEP-induced alveolar recruitment and clearance of anesthesia-induced atelectasis. Arterial oxygenation and static respiratory system compliance were significantly improved by use of PEEP. Pulmonary atelectasis can develop in anesthetized and mechanically ventilated sheep breathing pure oxygen; application of 10 cm H(2)O of PEEP significantly improved lung aeration and gas exchange.

  13. Effects of different levels of end-expiratory pressure on hemodynamic, respiratory mechanics and systemic stress response during laparoscopic cholecystectomy.

    PubMed

    Sen, Oznur; Erdogan Doventas, Yasemin

    General anesthesia causes reduction of functional residual capacity. And this decrease can lead to atelectasis and intrapulmonary shunting in the lung. In this study we want to evaluate the effects of 5 and 10cmH2O PEEP levels on gas exchange, hemodynamic, respiratory mechanics and systemic stress response in laparoscopic cholecystectomy. American Society of Anesthesiologist I-II physical status 43 patients scheduled for laparoscopic cholecystectomy were randomly selected to receive external PEEP of 5cmH2O (PEEP 5 group) or 10cmH2O PEEP (PEEP 10 group) during pneumoperitoneum. Basal hemodynamic parameters were recorded, and arterial blood gases (ABG) and blood sampling were done for cortisol, insulin and glucose level estimations to assess the systemic stress response before induction of anesthesia. Thirty minutes after the pneumoperitoneum, the respiratory and hemodynamic parameters were recorded again and ABG and sampling for cortisol, insulin, and glucose levels were repeated. Lastly hemodynamic parameters were recorded; ABG analysis and sampling for stress response levels were taken after 60minutes from extubation. There were no statistical differences between the two groups about hemodynamic and respiratory parameters except mean airway pressure (Pmean). Pmean, compliance and PaO2; pH values were higher in 'PEEP 10 group'. Also, PaCO2 values were lower in 'PEEP 10 group'. No differences were observed between insulin and lactic acid levels in the two groups. But postoperative cortisol level was significantly lower in 'PEEP 10 group'. Ventilation with 10cmH2O PEEP increases compliance and oxygenation, does not cause hemodynamic and respiratory complications and reduces the postoperative stress response. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Published by Elsevier Editora Ltda. All rights reserved.

  14. [Effects of different levels of end-expiratory pressure on hemodynamic, respiratory mechanics and systemic stress response during laparoscopic cholecystectomy].

    PubMed

    Sen, Oznur; Erdogan Doventas, Yasemin

    General anesthesia causes reduction of functional residual capacity. And this decrease can lead to atelectasis and intrapulmonary shunting in the lung. In this study we want to evaluate the effects of 5 and 10cmH2O PEEP levels on gas exchange, hemodynamic, respiratory mechanics and systemic stress response in laparoscopic cholecystectomy. American Society of Anesthesiologist I-II physical status 43 patients scheduled for laparoscopic cholecystectomy were randomly selected to receive external PEEP of 5cmH2O (PEEP 5 group) or 10cmH2O PEEP (PEEP 10 group) during pneumoperitoneum. Basal hemodynamic parameters were recorded, and arterial blood gases (ABG) and blood sampling were done for cortisol, insulin and glucose level estimations to assess the systemic stress response before induction of anesthesia. Thirty minutes after the pneumoperitoneum, the respiratory and hemodynamic parameters were recorded again and ABG and sampling for cortisol, insulin, and glucose levels were repeated. Lastly hemodynamic parameters were recorded; ABG analysis and sampling for stress response levels were taken after 60minutes from extubation. There were no statistical differences between the two groups about hemodynamic and respiratory parameters except mean airway pressure (Pmean). Pmean, compliance and PaO2; pH values were higher in 'PEEP 10 group'. Also, PaCO2 values were lower in 'PEEP 10 group'. No differences were observed between insulin and lactic acid levels in the two groups. But postoperative cortisol level was significantly lower in 'PEEP 10 group'. Ventilation with 10cmH2O PEEP increases compliance and oxygenation, does not cause hemodynamic and respiratory complications and reduces the postoperative stress response. Copyright © 2016 Sociedade Brasileira de Anestesiologia. Publicado por Elsevier Editora Ltda. All rights reserved.

  15. Extrapolation of a non-linear autoregressive model of pulmonary mechanics.

    PubMed

    Langdon, Ruby; Docherty, Paul D; Chiew, Yeong Shiong; Chase, J Geoffrey

    2017-02-01

    For patients with acute respiratory distress syndrome (ARDS), mechanical ventilation (MV) is an essential therapy in the intensive care unit (ICU). Suboptimal PEEP levels in MV can cause ventilator induced lung injury, which is associated with increased mortality, extended ICU stay, and high cost. The ability to predict the outcome of respiratory mechanics in response to changes in PEEP would thus provide a critical advantage in personalising and improving care. Testing the potentially dangerous high pressures would not be required to assess their impact. A nonlinear autoregressive (NARX) model was used to predict airway pressure in 19 data sets from 10 mechanically ventilated ARDS patients. Patient-specific NARX models were identified from pressure and flow data over one, two, three, or four adjacent PEEP levels in a recruitment manoeuvre. Extrapolation of NARX model elastance functions allowed prediction of patient responses to PEEP changes to higher or lower pressures. NARX model predictions were more successful than those using a well validated first order model (FOM). The most clinically important results were for extrapolation up one PEEP step of 2cmH2O from the highest PEEP in the training data. When the NARX model was trained on one PEEP level, the mean RMS residual for the extrapolation PEEP level was 0.52 (90% CI: 0.47-0.57) cmH2O, compared to 1.50 (90% CI: 1.38-1.62) cmH2O for the FOM. When trained on four PEEP levels, the NARX result was 0.50 (90% CI: 0.42-0.58) cmH2O, and was 1.95 (90% CI: 1.71-2.19) cmH2O for the FOM. The results suggest that a full recruitment manoeuvre may not be required for the NARX model to obtain a useful estimate of the pressure waveform at higher PEEP levels. The methodology could thus allow clinicians to make informed decisions about ventilator PEEP settings while reducing the risk associated with high PEEP, and subsequent high peak airway pressures.

  16. Measurement of functional residual capacity in rabbits and children using an ultrasonic flow meter.

    PubMed

    Schibler, A; Henning, R

    2001-04-01

    A sulfur hexafluoride (SF(6)) washin/washout technique was developed using an ultrasonic flowmeter to measure functional residual capacity (FRC) during mechanical ventilation. The ultrasonic flowmeter measures simultaneously flow and molar mass of the mainstream gas. Ventilation distribution was studied using moment ratios analysis (alveolar-based mean dilution number). Accuracy and precision of the measurement technique were tested in a mechanical lung model, and the method's sensitivity to changes of FRC was assessed in seven ventilated rabbits and six children. In the mechanical lung model with a volume range from 10 to 60 mL, the mean error of FRC measurement was 0.096 +/- 0.9 mL (range, 0-2 mL). In seven rabbits (mean body weight, 3.6 kg), measurements of FRC and alveolar-based mean dilution number were made at positive end-expiratory pressures (PEEP) of 0, 3, and 6 cm H(2)O. The mean coefficient of variation of 66 FRC-measurements was 5.5% (range, 0-15.3%). As the applied PEEP increased, mean FRC per kilogram body weight increased from 13.3 +/- 3.4 mL/kg (PEEP of 0 cm H(2)O) to 16.7 +/- 3.6 mL/kg (PEEP of 3 cm H(2)O) and to 20.8 +/- 4.3 mL/kg (PEEP of 6 cm H(2)O). Alveolar-based mean dilution number decreased accordingly from 1.94 +/- 0.42 (PEEP = 0; mean +/- SD), to 1.91 +/- 0.45 (PEEP = 3) and to 1.59 +/- 0.35 (PEEP = 6). In the six children, as applied PEEP increased, mean FRC per kilogram increased from 21.1 +/- 4.51 mL/kg (PEEP = 0), to 22.4 +/- 1.8 mL/kg (PEEP = 5) and 27.2 +/- 3.4 mL/kg (PEEP = 10). FRC measurement using the ultrasonic flowmeter is accurate and simple to use in ventilated and spontaneously breathing children.

  17. Volume-independent elastance: a useful parameter for open-lung positive end-expiratory pressure adjustment.

    PubMed

    Carvalho, Alysson Roncally; Bergamini, Bruno Curty; Carvalho, Niedja S; Cagido, Viviane R; Neto, Alcendino C; Jandre, Frederico C; Zin, Walter A; Giannella-Neto, Antonio

    2013-03-01

    A decremental positive end-expiratory pressure (PEEP) trial after full lung recruitment allows for the adjustment of the lowest PEEP that prevents end-expiratory collapse (open-lung PEEP). For a tidal volume (Vt) approaching zero, the PEEP of minimum respiratory system elastance (PEEP(minErs)) is theoretically equal to the pressure at the mathematical inflection point (MIP) of the pressure-volume curve, and seems to correspond to the open-lung PEEP in a decremental PEEP trial. Nevertheless, the PEEP(minErs) is dependent on Vt and decreases as Vt increases. To circumvent this dependency, we proposed the use of a second-order model in which the volume-independent elastance (E1) is used to set open-lung PEEP. Pressure-volume curves and a recruitment maneuver followed by decremental PEEP trials, with a Vt of 6 and 12 mL/kg, were performed in 24 Wistar rats with acute lung injury induced by intraperitoneally injected (n = 8) or intratracheally instilled (n = 8) Escherichia coli lipopolysaccharide. In 8 control animals, the anterior chest wall was surgically removed after PEEP trials, and the protocol was repeated. Airway pressure (Paw) and flow (F) were continuously acquired and fitted by the linear single-compartment model (Paw = Rrs·F + Ers·V + PEEP, where Rrs is the resistance of the respiratory system, and V is volume) and the volume-dependent elastance model (Paw = Rrs·F + E1 + E2·V·V + PEEP, where E2·V is the volume-dependent elastance). From each model, PEEPs of minimum Ers and E1 (PEEP(minE1)) were identified and compared with each respective MIP. The accuracy of PEEPminE1 and PEEPminErs in estimating MIP was assessed by bias and precision plots. Comparisons among groups were performed with the unpaired t test whereas a paired t test was used between the control group before and after chest wall removal and within groups at different Vts. All P values were then corrected for multiple comparisons by the Bonferroni procedure. In all experimental groups

  18. Haze Before Ice

    NASA Image and Video Library

    2011-12-22

    Saturn moon Tethys, with its stark white icy surface, peeps out from behind the larger, hazy, colorful Titan in this view of the two moons obtained by NASA Cassini spacecraft. Saturn rings lie between the two.

  19. Effect of Positive End-Expiratory Pressure on Central Venous Pressure in Patients under Mechanical Ventilation

    PubMed Central

    Shojaee, Majid; Sabzghabaei, Anita; Alimohammadi, Hossein; Derakhshanfar, Hojjat; Amini, Afshin; Esmailzadeh, Bahareh

    2017-01-01

    Introduction: Finding the probable governing pattern of PEEP and CVP changes is an area of interest for in-charge physicians and researchers. Therefore, the present study was designed with the aim of evaluating the relationship between the mentioned pressures. Methods: In this quasi-experimental study, patients under mechanical ventilation were evaluated with the aim of assessing the effect of PEEP change on CVP. Non-trauma patients, over 18 years of age, who were under mechanical ventilation and had stable hemodynamics, with inserted CV line were entered. After gathering demographic data, patients underwent 0, 5, and 10 cmH2O PEEPs and the respective CVPs of the mentioned points were recorded. The relationship of CVP and PEEP in different cut points were measured using SPSS 21.0 statistical software. Results: 60 patients with the mean age of 73.95 ± 11.58 years were evaluated (68.3% male). The most frequent cause of ICU admission was sepsis with 45.0%. 5 cmH2O increase in PEEP led to 2.47 ± 1.53 mean difference in CVP level. If the PEEP baseline is 0 at the time of 5 cmH2O increase, it leads to a higher raise in CVP compared to when the baseline is 5 cmH2O (2.47 ± 1.53 vs. 1.57 ± 1.07; p = 0.039). The relationship between CVP and 5 cmH2O (p = 0.279), and 10 cmH2O (p = 0.292) PEEP changes were not dependent on the baseline level of CVP. Conclusion: The findings of this study revealed the direct relationship between PEEP and CVP. Approximately, a 5 cmH2O increase in PEEP will be associated with about 2.5 cmH2O raise in CVP. When applying a 5 cmH2O PEEP increase, if the baseline PEEP is 0, it leads to a significantly higher raise in CVP compared to when it is 5 cmH2O (2.5 vs. 1.6). It seems that sex, history of cardiac failure, baseline CVP level, and hypertension do not have a significant effect in this regard. PMID:28286808

  20. Effects of the Trendelenburg Position and Positive End-Expiratory Pressure on the Internal Jugular Vein Cross-Sectional Area in Children With Simple Congenital Heart Defects.

    PubMed

    Kim, Hee Yeong; Choi, Jae Moon; Lee, Yong-Hun; Lee, Sukyung; Yoo, Hwanhee; Gwak, Mijeung

    2016-05-01

    Catheterization of the internal jugular vein (IJV) remains difficult in pediatric populations. Increasing the cross-sectional area (CSA) of the IJV facilitates cannulation and decreases complications. We aimed to evaluate the Trendelenburg position and the levels of positive end-expiratory pressure (PEEP) at which the maximum increase of CSA of the IJV occurred in children undergoing cardiac surgery.In this prospective study, the CSA of the right IJV was assessed using ultrasound in 47 anesthetized pediatric patients with simple congenital heart defects. The baseline CSA was obtained in response to a supine position with no PEEP and compared with 5 different randomly ordered maneuvers, that is, a PEEP of 5 and 10 cm H2O in a supine position and of 0, 5, and 10 cm H2O in a 10° Trendelenburg position. Hemodynamic variables, including blood pressure and heart rate, maximum and minimum diameters, and CSA, were measured.All maneuvers increased the CSA of the right IJV with respect to the control condition. In the supine position, the CSA was increased by 9.4% with a PEEP of 5 and by 19.5% with a PEEP of 10 cm H2O. The Trendelenburg tilt alone increased the CSA by 19.0%, and combining the 10° Trendelenburg with a 10 cm H2O PEEP resulted in the largest IJV CSA increase (33.3%) compared with the supine position with no PEEP. Meanwhile, vital signs remained relatively steady during the experiment.The application of the Trendelenburg position and a 10 cm H2O PEEP thus significantly increases the CSA of the right IJV, perhaps improving the chances of successful cannulation in pediatric patients with simple congenital heart defects.

  1. The Use of ATP-MgC1(2) in the Treatment of Injury and Shock.

    DTIC Science & Technology

    1979-12-01

    RBC Na+ have been observed in several pathological states, including uremia burns , trauma and hemorrhagic shock. Our previous preliminary experiments...carried out to examine the cardiopulmonary response to PEEP in dogs before and after the intratrachael inoculation of an inoculum of Psuedomonas ...conducted to test PAM fupq tion after PEEP with an in vitro system for quantitating the uptake of Cm’-labelled Psuedomonas orgnsmsby PAMs in tissue

  2. Positive end-expiratory pressure prevents the loss of respiratory compliance during low tidal volume ventilation in acute lung injury patients.

    PubMed

    Cereda, M; Foti, G; Musch, G; Sparacino, M E; Pesenti, A

    1996-02-01

    To study the effect of positive end-expiratory pressure (PEEP) on the decay of respiratory system compliance (Cpl,rs) due to low tidal volume (VT) ventilation in acute lung injury (ALI) patients. General ICU in a university hospital. Eight ALI patients with a lung injury score greater than 2.5. Pressure-controlled ventilation (PCV) and volume-controlled ventilation (VCV), with an average VT of 8.5 +/- 0.4 mL/kg, were applied at three levels of PEEP (5, 10, and 15 cm H2O). Before each PCV and VCV period, lung volume history was standardized by manual hyperinflation maneuvers. We measured Cpl,rs at time 0 (start), 10, 20, and 30 (end) min from the beginning of each PCV and VCV period. Gas exchange and hemodynamic data were collected at end. At PEEP 5 and 10 cm H2O, we observed a progressive Cpl,rs decay with both PCV and VCV modes. At PEEP 5 cm H2O, we detected a higher Cpl,rs decrease during PCV, due to a higher Cpl,rs at start, compared with VCV. At PEEP 15 cm H2O, Cpl,rs did not decrease significantly. Cpl,rs values measured at end as well as oxygenation and hemodynamic data did not differ between PCV and VCV. At PEEP 15 cm H2O, PCV provided lower PaCO2 than VCV. A PEEP of at least 15 cm H2O was needed to prevent Cpl,rs decay. The progressive Cpl,rs loss we observed at lower PEEP probably reflects alveolar instability.

  3. Effects of the Trendelenburg Position and Positive End-Expiratory Pressure on the Internal Jugular Vein Cross-Sectional Area in Children With Simple Congenital Heart Defects

    PubMed Central

    Kim, Hee Yeong; Choi, Jae Moon; Lee, Yong-Hun; Lee, Sukyung; Yoo, Hwanhee; Gwak, Mijeung

    2016-01-01

    Abstract Catheterization of the internal jugular vein (IJV) remains difficult in pediatric populations. Increasing the cross-sectional area (CSA) of the IJV facilitates cannulation and decreases complications. We aimed to evaluate the Trendelenburg position and the levels of positive end-expiratory pressure (PEEP) at which the maximum increase of CSA of the IJV occurred in children undergoing cardiac surgery. In this prospective study, the CSA of the right IJV was assessed using ultrasound in 47 anesthetized pediatric patients with simple congenital heart defects. The baseline CSA was obtained in response to a supine position with no PEEP and compared with 5 different randomly ordered maneuvers, that is, a PEEP of 5 and 10 cm H2O in a supine position and of 0, 5, and 10 cm H2O in a 10° Trendelenburg position. Hemodynamic variables, including blood pressure and heart rate, maximum and minimum diameters, and CSA, were measured. All maneuvers increased the CSA of the right IJV with respect to the control condition. In the supine position, the CSA was increased by 9.4% with a PEEP of 5 and by 19.5% with a PEEP of 10 cm H2O. The Trendelenburg tilt alone increased the CSA by 19.0%, and combining the 10° Trendelenburg with a 10 cm H2O PEEP resulted in the largest IJV CSA increase (33.3%) compared with the supine position with no PEEP. Meanwhile, vital signs remained relatively steady during the experiment. The application of the Trendelenburg position and a 10 cm H2O PEEP thus significantly increases the CSA of the right IJV, perhaps improving the chances of successful cannulation in pediatric patients with simple congenital heart defects. PMID:27149455

  4. Evidence for the infiltration of gas bubbles into the arterial circulation and neuronal injury following "yo-yo" dives in pigs.

    PubMed

    Ofir, Dror; Yanir, Yoav; Mullokandov, Michael; Aviner, Ben; Arieli, Yehuda

    2016-11-01

    "Yo-yo" diving may place divers at a greater risk of neurologic decompression illness (DCI). Using a rat model, we previously demonstrated that "yo-yo" diving has a protective effect against DCI. In the current study, we evaluated the risk of neurologic DCI following "yo-yo" dives in a pig model. Pigs were divided into four groups. The Control group (group A) made a square dive, without excursions to the surface ("peeps"). Group B performed two "peeps," group C performed four "peeps," and group D did not dive at all. All dives were conducted on air to 5 atm absolute, for 30-min bottom time. Echocardiography was performed to detect cardiac gas bubbles before the dive, immediately after, and at 90-min postdive. Motor performance was observed during the 5-h postdive period. Symptoms increased dramatically following a dive with four "peeps." Gas bubbles were detected in the right ventricle of all animals except for the sham group and in the left ventricle only after the four-peep dive. Neuronal cell injury was found in the spinal cord in each of the three experimental groups, tending to decrease with an increase in the number of "peeps." A four-peep "yo-yo" dive significantly increased the risk of neurologic DCI in pigs. Following a four-peep dive, we detected a higher incidence of bubbles in the left ventricle, supporting the common concern regarding an increased risk of neurologic DCI, albeit there was no direct correlation with the frequency of "red neurons" in the spinal cord.

  5. Positive end-expiratory pressure optimization using electric impedance tomography in morbidly obese patients during laparoscopic gastric bypass surgery.

    PubMed

    Erlandsson, K; Odenstedt, H; Lundin, S; Stenqvist, O

    2006-08-01

    Morbidly obese patients have an increased risk for peri-operative lung complications and develop a decrease in functional residual capacity (FRC). Electric impedance tomography (EIT) can be used for continuous, fast-response measurement of lung volume changes. This method was used to optimize positive end-expiratory pressure (PEEP) to maintain FRC. Fifteen patients with a body mass index of 49 +/- 8 kg/m(2) were studied during anaesthesia for laparoscopic gastric bypass surgery. Before induction, 16 electrodes were placed around the thorax to monitor ventilation-induced impedance changes. Calibration of the electric impedance tomograph against lung volume changes was made by increasing the tidal volume in steps of 200 ml. PEEP was titrated stepwise to maintain a horizontal baseline of the EIT curve, corresponding to a stable FRC. Absolute FRC was measured with a nitrogen wash-out/wash-in technique. Cardiac output was measured with an oesophageal Doppler method. Volume expanders, 1 +/- 0.5 l, were given to prevent PEEP-induced haemodynamic impairment. Impedance changes closely followed tidal volume changes (R(2) > 0.95). The optimal PEEP level was 15 +/- 1 cmH(2)O, and FRC at this PEEP level was 1706 +/- 447 ml before and 2210 +/- 540 ml after surgery (P < 0.01). The cardiac index increased significantly from 2.6 +/- 0.5 before to 3.1 +/- 0.8 l/min/m(2) after surgery, and the alveolar dead space decreased. P(a)O2/F(i)O2, shunt and compliance remained unchanged. EIT enables rapid assessment of lung volume changes in morbidly obese patients, and optimization of PEEP. High PEEP levels need to be used to maintain a normal FRC and to minimize shunt. Volume loading prevents circulatory depression in spite of a high PEEP level.

  6. Combined effects of ventilation mode and positive end-expiratory pressure on mechanics, gas exchange and the epithelium in mice with acute lung injury.

    PubMed

    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 (V(T)) 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-V(T) 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 cmH(2)O with conventional ventilation (CV), CV with intermittent large breaths (CV(LB)) to promote recruitment, and a new mode, variable ventilation, optimized for mice (VV(N)). 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 CV(LB) was better than CV, VV(N) outperformed CV(LB) 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.

  7. Stress index for positive end-expiratory pressure titration in prone position: a piglet study.

    PubMed

    Pan, C; Tang, R; Xie, J; Xu, J; Liu, S; Yu, T; Huang, Y; Guo, F; Yang, Y; Qiu, H

    2015-10-01

    Prone position ventilation is an important treatment for acute respiratory distress syndrome (ARDS), but chest wall elastance increases in prone position ventilation, and stress index may not reflect the changes in lung mechanics. We therefore investigated the effects of stress index guided PEEP titration on pulmonary mechanics and hemodynamics in the prone position in a piglet acute lung injury model. Ten piglets with severe lavage-induced lung injury were mechanically ventilated in a decremental PEEP trial after full lung recruitment in the prone position. Stress-index PEEP was the level at which the airway pressure stress index was 1, and open-lung PEEP was the level at which it was required to keep the lung open according to computed tomography (CT) scans. Respiratory mechanics, blood gases, hemodynamics, and whole-lung CT were recorded at the two PEEP levels. Respiratory system elastance and lung elastance were improved in the prone position but the ratio of chest wall elastance and respiratory system elastance was higher in the prone position. There was no significant difference between open-lung and stress-index guided PEEPs in the prone position (P = 0.46). There was no significant difference between collapsed lung volume (P = 0.07) and hyperinflation lung volume (P = 0.76) in the two groups. Similarly, there was no significant difference between open-lung and stress-index guided PEEPs in terms of oxygenation index (P = 0.95) and PaCO2 (P = 0.42). Stress index can be used to titrate PEEP in the prone position in a surfactant-depleted lung injury model. © 2015 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  8. Prolonged moderate pressure recruitment manoeuvre results in lower optimal positive end-expiratory pressure and plateau pressure.

    PubMed

    Lowhagen, K; Lindgren, S; Odenstedt, H; Stenqvist, O; Lundin, S

    2011-02-01

    In acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), recruitment manoeuvres (RMs) are used frequently. In pigs with induced ALI, superior effects have been found using a slow moderate-pressure recruitment manoeuvre (SLRM) compared with a vital capacity recruitment manoeuvre (VICM). We hypothesized that the positive recruitment effects of SLRM could also be achieved in ALI/ARDS patients. Our primary research question was whether the same compliance could be obtained using lower RM pressure and subsequent positive end-expiratory pressure (PEEP). Secondly, optimal PEEP levels following the RMs were compared, and the use of volume-dependent compliance (VDC) to identify successful lung recruitment and optimal PEEP was evaluated. We performed a prospective randomised cross-over study where 16 ventilated patients with early ALI/ARDS each were subjected to the two RMs, followed by decremental PEEP titration. Volume-dependent initial, middle and final compliance (C(ini) , C(mid) and C(fin) ) were determined. Electric impedance tomography and end-expiratory lung volume measurements were used to follow lung volume changes. The maximum response in compliance, PaO₂/FIO₂, venous admixture and C(ini) /C(fin) after recruitment, during decremental PEEP, was at significantly lower PEEP and plateau pressure after SLRM than VICM. Fewer patients responded in gas exchange after the SLRM, which was not the case for lung mechanics. The response in C(ini) was more pronounced than in conventional compliance. The same compliance increase is achieved with SLRM as with VICM, and lower PEEP can be used, with correspondingly lower plateau pressures. VDC seems promising to identify successful recruitment and optimal PEEP. © 2011 The Authors. Journal compilation © 2011 The Acta Anaesthesiologica Scandinavica Foundation.

  9. Effect of Positive End-Expiratory Pressure on the Sonographic Optic Nerve Sheath Diameter as a Surrogate for Intracranial Pressure during Robot-Assisted Laparoscopic Prostatectomy: A Randomized Controlled Trial

    PubMed Central

    Chin, Ji-Hyun; Kim, Wook-Jong; Lee, Joonho; Han, Yun A.; Lim, Jinwook; Hwang, Jai-Hyun; Cho, Seong-Sik

    2017-01-01

    Background Positive end-expiratory pressure (PEEP) can increase intracranial pressure. Pneumoperitoneum and the Trendelenburg position are associated with an increased intracranial pressure. We investigated whether PEEP ventilation could additionally influence the sonographic optic nerve sheath diameter as a surrogate for intracranial pressure during pneumoperitoneum combined with the Trendelenburg position in patients undergoing robot-assisted laparoscopic prostatectomy. Methods After anesthetic induction, 38 patients were randomly allocated to a low tidal volume ventilation (8 ml/kg) without PEEP group (zero end-expiratory pressure [ZEEP] group, n = 19) or low tidal volume ventilation with 8 cmH2O PEEP group (PEEP group, n = 19). The sonographic optic nerve sheath diameter was measured prior to skin incision, 5 min and 30 min after pneumoperitoneum and the Trendelenburg position, and at the end of surgery. The study endpoint was the difference in the sonographic optic nerve sheath diameter 5 min after pneumoperitoneum and the Trendelenburg position between the ZEEP and PEEP groups. Results Optic nerve sheath diameters 5 min after pneumoperitoneum and the Trendelenburg position did not significantly differ between the groups [least square mean (95% confidence interval); 4.8 (4.6–4.9) mm vs 4.8 (4.7–5.0) mm, P = 0.618]. Optic nerve sheath diameters 30 min after pneumoperitoneum and the Trendelenburg position also did not differ between the groups [least square mean (95% confidence interval); 4.5 (4.3–4.6) mm vs 4.5 (4.4–4.6) mm, P = 0.733]. Conclusions An 8 cmH2O PEEP application under low tidal volume ventilation does not induce an increase in the optic nerve sheath diameter during pneumoperitoneum combined with the steep Trendelenburg position, suggesting that there might be no detrimental effects of PEEP on the intracranial pressure during robot-assisted laparoscopic prostatectomy. Trial Registration ClinicalTrial.gov NCT02516566 PMID:28107408

  10. 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

  11. High positive end-expiratory pressure: only a dam against oedema formation?

    PubMed Central

    2013-01-01

    Introduction Healthy piglets ventilated with no positive end-expiratory pressure (PEEP) and with tidal volume (VT) close to inspiratory capacity (IC) develop fatal pulmonary oedema within 36 h. In contrast, those ventilated with high PEEP and low VT, resulting in the same volume of gas inflated (close to IC), do not. If the real threat to the blood-gas barrier is lung overinflation, then a similar damage will occur with the two settings. If PEEP only hydrostatically counteracts fluid filtration, then its removal will lead to oedema formation, thus revealing the deleterious effects of overinflation. Methods Following baseline lung computed tomography (CT), five healthy piglets were ventilated with high PEEP (volume of gas around 75% of IC) and low VT (25% of IC) for 36 h. PEEP was then suddenly zeroed and low VT was maintained for 18 h. Oedema was diagnosed if final lung weight (measured on a balance following autopsy) exceeded the initial one (CT). Results Animals were ventilated with PEEP 18 ± 1 cmH2O (volume of gas 875 ± 178 ml, 89 ± 7% of IC) and VT 213 ± 10 ml (22 ± 5% of IC) for the first 36 h, and with no PEEP and VT 213 ± 10 ml for the last 18 h. On average, final lung weight was not higher, and actually it was even lower, than the initial one (284 ± 62 vs. 347 ± 36 g; P = 0.01). Conclusions High PEEP (and low VT) do not merely impede fluid extravasation but rather preserve the integrity of the blood-gas barrier in healthy lungs. PMID:23844622

  12. Ultrasonographic investigation of the effect of positive end-expiratory pressure on the cross-sectional area of the femoral vein.

    PubMed

    Ryu, J H; Han, S S; Choi, W J; Kim, H; Lee, S C; Do, S H; Son, Y K

    2013-02-01

    Femoral veins are commonly used as a relatively safe alternative route for central venous cannulation. Several maneuvers are used to increase the cross-sectional area of the vein. In this study, we assessed the effect of positive end-expiratory pressure (PEEP) on the cross-sectional area (CSA) of femoral veins, using ultrasound in adult patients under positive pressure ventilation. All patients received a standardized induction of general anesthesia and intravenous fluid administration. Using ultrasound, the cross-sectional areas of both femoral veins were measured in 57 adult patients in the supine position without PEEP (control) and in the supine position with PEEP of 10 cm H(2)O. Mean arterial pressure and heart rate were recorded before and after the application of PEEP at 10 cm H(2)O. The application of 10 cm H(2)O PEEP significantly increased the CSA of the right femoral vein by 47.6 % and the left femoral vein by 48.4 % (each P < 0.001). Mean arterial pressure decreased by 2.6 mmHg (95 % CI 1.3-3.9; P < 0.001), whereas no significant change in heart rate was observed (P = 0.861). The CSA of the femoral vein is augmented with the application of 10 cm H(2)O PEEP in adult patients undergoing positive pressure ventilation.

  13. The pressure-volume curve is greatly modified by recruitment. A mathematical model of ARDS lungs.

    PubMed

    Hickling, K G

    1998-07-01

    A mathematical model of the ARDS lung, with simulated gravitational superimposed pressure, evaluated the effect of varying alveolar threshold opening pressures (TOP), PEEP and peak inspiratory pressure (PIP) on the static pressure-volume (PV) curve. The lower inflection point (Pflex) was affected by SP and TOP, and did not accurately indicate PEEP required to prevent end-expiratory collapse. Reinflation of collapsed lung units (recruitment) continued on the linear portion of the PV curve, which had a slope at any volume greater than the total compliance of aerated alveoli. As recruitment diminished, the reduced PV slope could produce an upper Pflex at 20 to 30 cm H2O pressure. An upper Pflex caused by alveolar overdistension could be modified or eliminated by recruitment with high TOP. With constant PIP as PEEP increased, and TOP range of 5 to 60 cm H2O, PEEP to prevent end-expiratory collapse was indicated by minimum PV slope above 20 cm H2O, minimum hysteresis, and maximum volume at a pressure of 20 cm H2O. With constant inflation volume as PEEP increased, the effect on PV slope was unpredictable. Although increased PV slope indicated recruitment, maximum PV slope usually underestimated PEEP required to prevent end-expiratory collapse. Therefore, with this model the PV curve did not reliably predict optimal ventilator settings.

  14. Expiratory flow limitation in morbidly obese postoperative mechanically ventilated patients.

    PubMed

    Koutsoukou, A; Koulouris, N; Bekos, B; Sotiropoulou, C; Kosmas, E; Papadima, K; Roussos, C

    2004-10-01

    Although obesity promotes tidal expiratory flow limitation (EFL), with concurrent dynamic hyperinflation (DH), intrinsic PEEP (PEEPi) and risk of low lung volume injury, the prevalence and magnitude of EFL, DH and PEEPi have not yet been studied in mechanically ventilated morbidly obese subjects. In 15 postoperative mechanically ventilated morbidly obese subjects, we assessed the prevalence of EFL [using the negative expiratory pressure (NEP) technique], PEEPi, DH, respiratory mechanics, arterial oxygenation and PEEPi inequality index as well as the levels of PEEP required to abolish EFL. In supine position at zero PEEP, 10 patients exhibited EFL with a significantly higher PEEPi and DH and a significantly lower PEEPi inequality index than found in the five non-EFL (NEFL) subjects. Impaired gas exchange was found in all cases without significant differences between the EFL and NEFL subjects. Application of 7.5 +/- 2.5 cm H2O of PEEP (range: 4-16) abolished EFL with a reduction of PEEPi and DH and an increase in FRC and the PEEPi inequality index but no significant effect on gas exchange. The present study indicates that: (a) on zero PEEP, EFL is present in most postoperative mechanically ventilated morbidly obese subjects; (b) EFL (and concurrent risk of low lung volume injury) is abolished with appropriate levels of PEEP; and (c) impaired gas exchange is common in these patients, probably mainly due to atelectasis.

  15. Effects of increased positive end-expiratory pressure on intracranial pressure in acute respiratory distress syndrome: a protocol of a prospective physiological study

    PubMed Central

    Chen, Han; Xu, Ming; Yang, Yan-Lin; Chen, Kai; Xu, Jing-Qing; Zhang, Ying-Rui; Yu, Rong-Guo

    2016-01-01

    Introduction There are concerns that the use of positive end-expiratory pressure (PEEP) in patients with brain injury may potentially elevate intracranial pressure (ICP). However, the transmission of PEEP into the thoracic cavity depends on the properties of the lungs and the chest wall. When chest wall elastance is high, PEEP can significantly increase pleural pressure. In the present study, we investigate the different effects of PEEP on the pleural pressure and ICP in different respiratory mechanics. Methods and analysis This study is a prospective, single-centre, physiological study in patients with severe brain injury. Patients with acute respiratory distress syndrome with ventricular drainage will be enrolled. An oesophageal balloon catheter will be inserted to measure oesophageal pressure. Patients will be sedated and paralysed; airway pressure and oesophageal pressure will be measured during end-inspiratory occlusion and end-expiratory occlusion. Elastance of the chest wall, the lungs and the respiratory system will be calculated at PEEP levels of 5, 10 and 15 cm H2O. We will classify each patient based on the maximal ΔICP/ΔPEEP being above or below the median for the study population. 2 groups will thus be compared. Ethics and dissemination The study protocol and consent forms were approved by the Institutional Review Board of Fujian Provincial Hospital. Study findings will be disseminated through peer-reviewed publications and conference presentations. Trial registration number NCT02670733; pre-results. PMID:27852713

  16. Ventilation with increased apparatus dead space vs positive end-expiratory pressure: effects on gas exchange and circulation during anesthesia in a randomized clinical study.

    PubMed

    Enekvist, Bruno; Bodelsson, Mikael; Chew, Michelle; Johansson, Anders

    2014-04-01

    Atelectasis formation can be reduced by positive end-expiratory pressure (PEEP), but resulting increases in intrathoracic pressure could affect circulation. We have earlier demonstrated that increased tidal volumes with larger apparatus dead space improves oxygenation and sevoflurane uptake. In the present study, we hypothesize that isocapnic ventilation with increased tidal volumes increases oxygen and sevoflurane uptake similar to ventilation with PEEP, but with less impact on cardiac output. Thirty patients, with ASA physical status 1 or 2, scheduled for elective open colon surgery were randomly assigned to be ventilated with either PEEP at 10 cm H20 (PEEP, 15 patients) or increased tidal volumes achieved with larger apparatus dead space but with zero end-expiratory pressure (DS group, 15 patients). Oxygen tension and arterial sevoflurane concentration were significantly higher in the DS group (P < .05). Cardiac output decreased significantly less in the DS group compared with the PEEP group (5% and 33%, respectively; P < .05). Consequently, isocapnic ventilation with increased tidal volumes using apparatus dead space increased oxygen and sevoflurane tensions in arterial blood and preserved cardiac output better than did PEEP.

  17. End-Expiratory Lung Volume in Patients with Acute Respiratory Distress Syndrome: A Time Course Analysis.

    PubMed

    Kalenka, Armin; Gruner, Felix; Weiß, Christel; Viergutz, Tim

    2016-08-01

    Lung injury can be caused by ventilation and non-physiological lung stress (transpulmonary pressure) and strain [inflated volume over functional residual capacity ratio (FRC)]. FRC is severely decreased in patients with acute respiratory distress syndrome (ARDS). End-expiratory lung volume (EELV) is FRC plus lung volume increased by the applied positive end-expiratory pressure (PEEP). Measurement using the modified nitrogen multiple breath washout technique may help titrating PEEP during ARDS and allow determining dynamic lung strain (tidal volume over EELV) in patients ventilated with PEEP. In this observational study, we measured EELV for up to seven consecutive days in patients with ARDS at different PEEP levels. Thirty sedated patients with ARDS (10 mild, 14 moderate, 6 severe) underwent decremental PEEP testing (20, 15, 10, 5 cm H2O) for up to 7 days after inclusion. At all PEEP levels examined, over a period of 7 days the measured absolute EELVs showed no significant change over time [PEEP 20 cm H2O 2464 ml at day 1 vs. 2144 ml at day 7 (p = 0.78), PEEP 15 cm H2O 2226 ml vs. 1990 ml (p = 0.36), PEEP 10 1835 ml vs. 1858 ml (p = 0.76) and PEEP 5 cm H2O 1487 ml vs. 1612 ml (p = 0.37)]. In relation to the predicted body weight (pbw), no significant change in EELV/kg pbw over time could be detected either at any PEEP level or over time [PEEP 20 36 ml/kg pbw at day 1 vs. 33 ml/kg pbw at day 7 (p = 0.66); PEEP 15 33 vs. 29 ml/kg pbw (p = 0.32); PEEP 10 27 vs. 27 ml/kg pbw (p = 0.70) and PEEP 5 22 vs. 24 ml/kg pbw (p = 0.70)]. Oxygenation significantly improved over time from PaO2/FiO2 of 169 mmHg at day 1 to 199 mmHg at day 7 (p < 0.01). EELV did not change significantly for up to 7 days in patients with ARDS. By contrast, PaO2/FiO2 improved significantly. Bedside measurement of EELV may be a novel approach to individualise lung-protective ventilation on the basis of calculation of dynamic strain as the ratio of VT to EELV.

  18. Gas exchange and lung mechanics in patients with acute respiratory distress syndrome: comparison of three different strategies of positive end expiratory pressure selection.

    PubMed

    Valentini, Ricardo; Aquino-Esperanza, José; Bonelli, Ignacio; Maskin, Patricio; Setten, Mariano; Danze, Florencia; Attie, Shiry; Rodriguez, Pablo O

    2015-04-01

    The purpose of the study was to compare gas exchange and lung mechanics between different strategies to select positive end-expiratory pressure (PEEP) in acute respiratory distress syndrome (ARDS). In 20 consecutive ARDS patients, 3 PEEP selection strategies were evaluated. One strategy was based on oxygenation using the ARDS network PEEP/fraction of inspired oxygen (Fio2) table; and two were based on lung mechanics, either PEEP titrated to reach a plateau pressure of 28 to 30 cm H2O as in the ExPress trial or best respiratory compliance method during a derecruitment maneuver. Gas exchange, airway pressures, stress index (SI), and end-expiratory transpulmonary pressure (P(tpe)) and end-inspiratory transpulmonary pressure (P(tpi)) values were assessed. Data are expressed as median (interquartile range [IQR]). Lower total PEEP levels were observed with the use of the PEEP/Fio2 table (8.7 [6-10] cm H2O); intermediate PEEP levels, with the Best Compliance approach (13.0 [10.2-13.8] cm H2O); and higher PEEP levels, with the ExPress strategy (16.5 [15.0-18.5] cm H2O) (P < .01). Pao2/Fio2 ratio was lower with the PEEP/Fio2 table. Oxygenation with Best Compliance approach and ExPress strategy was not different with lower plateau pressure in the former (23 [20-25] vs 30 [29-30] cm H2O; P < .01). Paco2 was slightly higher with the ExPress method than the others 2 strategies. Negative P(tpe) was observed in 35% of the patients with the PEEP/Fio2 table, in 15% applying the Best Compliance, and in only 1 case with the ExPress method. Higher SI and P(tpi), with lower lung compliance, were obtained with ExPress strategy. Using a best respiratory compliance approach resulted in better oxygenation levels without risk of overdistension according to SI and P(tpi), achieving a mild risk of lung collapse according to P(tpe). Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Intrinsic positive end-expiratory pressure during ventilation through small endotracheal tubes during general anesthesia: incidence, mechanism, and predictive factors.

    PubMed

    Gemma, Marco; Nicelli, Elisa; Corti, Daniele; De Vitis, Assunta; Patroniti, Nicolò; Foti, Giuseppe; Calvi, Maria Rosa; Beretta, Luigi

    2016-06-01

    To assess the safety of mechanical ventilation and effectiveness of extrinsic positive end-expiratory pressure (PEEP) (PEEPe) in improving peripheral oxygen saturation (SpO2) during direct microlaryngeal laser surgery; to assess the incidence, amount, and nature (dynamic hyperinflation or airflow obstruction) of ensuing intrinsic PEEP (PEEPi); and to find a surrogate PEEPi indicator. Quasiexperimental. S. Raffaele Hospital (Milano), November 2009 to December 2010. Fifty-two adults scheduled for direct microlaryngeal laser surgery. Exclusion criterion is pregnancy. Twenty-one percent O2 mechanical ventilation through 4.5- to 5.5-mm internal diameter endotracheal tubes; in 29 patients, after measurement of PEEPi, an identical amount of PEEPe was added; and PEEPi. SpO2, peak (Pawpeak) and plateau (Pawplateau) airway pressure, and end-expiratory carbon dioxide were measured every 5 minutes. Respiratory compliance (Crs) was computed. PEEPi was measured (end-expiratory occlusion method). PEEPi ≥5 cm H2O occurred in 14 patients (27%) after intubation, in 16 (30%) at the beginning, and in 14 (27.3%) at the end of surgery. Thirty-one patients (59.4%) exhibited PEEPi ≥5 cm H2O on at least 1 time point. PEEPi at the beginning of surgery was positively correlated with Pawplateau, Crs, tidal volume, and body mass index. Body mass index was the only predictor for the occurrence of PEEPi ≥5 cm H2O. At the beginning of surgery, the Pawplateau receiver operating characteristic curve predicting PEEPi ≥5 cm H2O had area under the receiver operating characteristic curve of 0.85; best cutoff value of 15.5 cm H2O (sensitivity, 88.9%; specificity, 75%; correctly classified cases, 86.1%). When PEEPe was applied, in 23 cases (82.1%), total PEEP equaled PEEPe+ PEEPi; in 3 (10.7%), it was lower; and in 2 (7.1%), it was higher. Application of PEEPe increased SpO2 (P< .05) and Crs (P< .05). During ventilation through small endotracheal tubes, PEEPi (mostly due to dynamic hyperinflation

  20. Positive End-Expiratory Pressure may alter breathing cardiovascular variability and baroreflex gain in mechanically ventilated patients

    PubMed Central

    2010-01-01

    Background Baroreflex allows to reduce sudden rises or falls of arterial pressure through parallel RR interval fluctuations induced by autonomic nervous system. During spontaneous breathing, the application of positive end-expiratory pressure (PEEP) may affect the autonomic nervous system, as suggested by changes in baroreflex efficiency and RR variability. During mechanical ventilation, some patients have stable cardiorespiratory phase difference and high-frequency amplitude of RR variability (HF-RR amplitude) over time and others do not. Our first hypothesis was that a steady pattern could be associated with reduced baroreflex sensitivity and HF-RR amplitude, reflecting a blunted autonomic nervous function. Our second hypothesis was that PEEP, widely used in critical care patients, could affect their autonomic function, promoting both steady pattern and reduced baroreflex sensitivity. Methods We tested the effect of increasing PEEP from 5 to 10 cm H2O on the breathing variability of arterial pressure and RR intervals, and on the baroreflex. Invasive arterial pressure, ECG and ventilatory flow were recorded in 23 mechanically ventilated patients during 15 minutes for both PEEP levels. HF amplitude of RR and systolic blood pressure (SBP) time series and HF phase differences between RR, SBP and ventilatory signals were continuously computed by complex demodulation. Cross-spectral analysis was used to assess the coherence and gain functions between RR and SBP, yielding baroreflex-sensitivity indices. Results At PEEP 10, the 12 patients with a stable pattern had lower baroreflex gain and HF-RR amplitude of variability than the 11 other patients. Increasing PEEP was generally associated with a decreased baroreflex gain and a greater stability of HF-RR amplitude and cardiorespiratory phase difference. Four patients who exhibited a variable pattern at PEEP 5 became stable at PEEP 10. At PEEP 10, a stable pattern was associated with higher organ failure score and

  1. Positive End-expiratory Pressure Titration after Alveolar Recruitment Directed by Electrical Impedance Tomography

    PubMed Central

    Long, Yun; Liu, Da-Wei; He, Huai-Wu; Zhao, Zhan-Qi

    2015-01-01

    Background: Electrical impedance tomography (EIT) is a real-time bedside monitoring tool, which can reflect dynamic regional lung ventilation. The aim of the present study was to monitor regional gas distribution in patients with acute respiratory distress syndrome (ARDS) during positive-end-expiratory pressure (PEEP) titration using EIT. Methods: Eighteen ARDS patients under mechanical ventilation in Department of Critical Care Medicine of Peking Union Medical College Hospital from January to April in 2014 were included in this prospective observational study. After recruitment maneuvers (RMs), decremental PEEP titration was performed from 20 cmH2O to 5 cmH2O in steps of 3 cmH2O every 5–10 min. Regional over-distension and recruitment were monitored with EIT. Results: After RMs, patient with arterial blood oxygen partial pressure (PaO2) + carbon dioxide partial pressure (PaCO2) >400 mmHg with 100% of fractional inspired oxygen concentration were defined as RM responders. Thirteen ARDS patients was diagnosed as responders whose PaO2 + PaCO2 were higher than nonresponders (419 ± 44 mmHg vs. 170 ± 73 mmHg, P < 0.0001). In responders, PEEP mainly increased recruited pixels in dependent regions and over-distended pixels in nondependent regions. PEEP alleviated global inhomogeneity of tidal volume and end-expiratory lung volume. PEEP levels without significant alveolar derecruitment and over-distension were identified individually. Conclusions: After RMs, PEEP titration significantly affected regional gas distribution in lung, which could be monitored with EIT. EIT has the potential to optimize PEEP titration. PMID:26021494

  2. Comparison of positive end-expiratory pressure-induced increase in central venous pressure and passive leg raising to predict fluid responsiveness in patients with atrial fibrillation.

    PubMed

    Kim, N; Shim, J-K; Choi, H G; Kim, M K; Kim, J Y; Kwak, Y-L

    2016-03-01

    Positive end-expiratory pressure (PEEP)-induced increase in central venous pressure (CVP) has been suggested to be a robust indicator of fluid responsiveness, with heart rhythm having minimal influence. We compared the ability of PEEP-induced changes in CVP with passive leg raising (PLR)-induced changes in stroke volume index (SVI) in patients with atrial fibrillation after valvular heart surgery. In 43 patients with atrial fibrillation after cardiac surgery, PEEP was increased from 0 to 10 cm H2O for 5 min and changes in CVP were assessed. After returning the PEEP to 0 cm H2O, PLR was performed for 5 min and changes in SVI were recorded. Finally, 300 ml of colloid was infused and haemodynamic variables were assessed 5 min after completion of a fluid challenge. Fluid responsiveness was defined as an increase in SVI ≥10% measured by a pulmonary artery catheter. Fifteen (35%) patients were fluid responders. There was no correlation between PEEP-induced increases in CVP and changes in SVI after a fluid challenge (β coefficient -0.052, P=0.740), whereas changes in SVI during PLR showed a significant correlation (β coefficient 0.713, P<0.001). The area under the receiver operating characteristic curve of the PEEP-induced increase in CVP and changes in SVI during PLR for fluid responsiveness was 0.556 [95% confidence interval (CI) 0.358-0.753, P=0.549) and 0.771 (95% CI 0.619-0.924, P=0.004), respectively. A PEEP-induced increase in CVP did not predict fluid responsiveness in patients with atrial fibrillation after cardiac surgery, but increases in SVI during PLR seem to be a valid predictor of fluid responsiveness in this subset of patients. © 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.

  3. Role of tidal volume, FRC, and end-inspiratory volume in the development of pulmonary edema following mechanical ventilation.

    PubMed

    Dreyfuss, D; Saumon, G

    1993-11-01

    Mechanical ventilation with high peak inspiratory pressure and large tidal volume (VT) produces permeability pulmonary edema. Whether it is mean or peak inspiratory pressure (i.e., mean or end-inspiratory volume) that is the major determinant of ventilation-induced lung injury is unsettled. Rats were ventilated with increasing tidal volumes starting from different degrees of FRC that were set by increasing end-expiratory pressure during positive-pressure ventilation. Pulmonary edema was assessed by the measurement of extravascular lung water content. The importance of permeability alterations was evaluated by measurement of dry lung weight and determination of albumin distribution space. Pulmonary edema with permeability alterations occurred regardless of the value of positive end-expiratory pressure (PEEP), provided the increase in VT was large enough. Similarly, edema occurred even during normal VT ventilation provided the increase in PEEP was large enough. Furthermore, moderate increases in VT or PEEP that were innocuous when applied alone, produced edema when combined. The effect of PEEP was not the consequence of raised airway pressure but of the increase in FRC since similar observations were made in animals ventilated with negative inspiratory pressure. However, although permeability alterations were similar, edema was less marked in animals ventilated with PEEP than in those ventilated with zero end-expiratory pressure (ZEEP) with the same end-inspiratory pressure. This "beneficial" effect of PEEP was probably the consequence of hemodynamic alterations. Indeed, infusion of dopamine to correct the drop in systemic arterial pressure that occurred during PEEP ventilation resulted in a significant increase in pulmonary edema. In conclusion, rather than VT or FRC value, the end-inspiratory volume is probably the main determinant of ventilation-induced edema. Hemodynamic status plays an important role in modulating the amount of edema during lung overinflation

  4. Capnodynamic assessment of effective lung volume during cardiac output manipulations in a porcine model.

    PubMed

    Hällsjö Sander, Caroline; Lönnqvist, Per-Arne; Hallbäck, Magnus; Sipmann, Fernando Suarez; Wallin, Mats; Oldner, Anders; Björne, Håkan

    2016-12-01

    A capnodynamic calculation of effective pulmonary blood flow includes a lung volume factor (ELV) that has to be estimated to solve the mathematical equation. In previous studies ELV correlated to reference methods for functional residual capacity (FRC). The aim was to evaluate the stability of ELV during significant manipulations of cardiac output (CO) and assess the agreement for absolute values and trending capacity during PEEP changes at different lung conditions. Ten pigs were included. Alterations of alveolar carbon dioxide were induced by cyclic reoccurring inspiratory holds. The Sulphur hexafluoride technique for FRC measurements was used as reference. Cardiac output was altered by preload reduction and inotropic stimulation at PEEP 5 and 12 cmH2O both in normal lung conditions and after repeated lung lavages. ELV at baseline PEEP 5 was [mean (SD)], 810 (163) mL and decreased to 400 (42) mL after lavage. ELV was not significantly affected by CO alterations within the same PEEP level. In relation to FRC the overall bias (limits of agreement) was -35 (-271 to 201) mL, and percentage error 36 %. A small difference between ELV and FRC was seen at PEEP 5 cmH2O before lavage and at PEEP 12 cmH2O after lavage. ELV trending capability between PEEP steps, showed a concordance rate of 100 %. ELV was closely related to FRC and remained stable during significant changes in CO. The trending capability was excellent both before and after surfactant depletion.

  5. Continuum and molecular-dynamics simulation of nanodroplet collisions.

    PubMed

    Bardia, Raunak; Liang, Zhi; Keblinski, Pawel; Trujillo, Mario F

    2016-05-01

    The extent to which the continuum treatment holds in binary droplet collisions is examined in the present work by using a continuum-based implicit surface capturing strategy (volume-of-fluid coupled to Navier-Stokes) and a molecular dynamics methodology. The droplet pairs are arranged in a head-on-collision configuration with an initial separation distance of 5.3 nm and a velocity of 3 ms^{-1}. The size of droplets ranges from 10-50 nm. Inspecting the results, the collision process can be described as consisting of two periods: a preimpact phase that ends with the initial contact of both droplets, and a postimpact phase characterized by the merging, deformation, and coalescence of the droplets. The largest difference between the continuum and molecular dynamics (MD) predictions is observed in the preimpact period, where the continuum-based viscous and pressure drag forces significantly overestimate the MD predictions. Due to large value of Knudsen number in the gas (Kn_{gas}=1.972), this behavior is expected. Besides the differences between continuum and MD, it is also observed that the continuum simulations do not converge for the set of grid sizes considered. This is shown to be directly related to the initial velocity profile and the minute size of the nanodroplets. For instance, for micrometer-size droplets, this numerical sensitivity is not an issue. During the postimpact period, both MD and continuum-based simulations are strikingly similar, with only a moderate difference in the peak kinetic energy recorded during the collision process. With values for the Knudsen number in the liquid (Kn_{liquid}=0.01 for D=36nm) much closer to the continuum regime, this behavior is expected. The 50 nm droplet case is sufficiently large to be predicted reasonably well with the continuum treatment. However, for droplets smaller than approximately 36 nm, the departure from continuum behavior becomes noticeably pronounced, and becomes drastically different for the 10 nm

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

    PubMed Central

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

    2007-01-01

    Introduction Acute respiratory distress syndrome causes a heterogeneous lung injury, and without protective mechanical ventilation a secondary ventilator-induced lung injury can occur. To ventilate noncompliant lung regions, high inflation pressures are required to 'pop open' the injured alveoli. The temporal impact, however, of these elevated pressures on normal alveolar mechanics (that is, the dynamic change in alveolar size and shape during ventilation) is unknown. In the present study we found that ventilating the normal lung with high peak pressure (45 cmH20) and low positive end-expiratory pressure (PEEP of 3 cmH2O) did not initially result in altered alveolar mechanics, but alveolar instability developed over time. Methods Anesthetized rats underwent tracheostomy, were placed on pressure control ventilation, and underwent sternotomy. Rats were then assigned to one of three ventilation strategies: control group (n = 3, Pcontrol = 14 cmH2O, PEEP = 3 cmH2O), high pressure/low PEEP group (n = 6, Pcontrol = 45 cmH2O, PEEP = 3 cmH2O), and high pressure/high PEEP group (n = 5, Pcontrol = 45 cmH2O, PEEP = 10 cmH2O). In vivo microscopic footage of subpleural alveolar stability (that is, recruitment/derecruitment) was taken at baseline and than every 15 minutes for 90 minutes following ventilator adjustments. Alveolar recruitment/derecruitment was determined by measuring the area of individual alveoli at peak inspiration (I) and end expiration (E) by computer image analysis. Alveolar recruitment/derecruitment was quantified by the percentage change in alveolar area during tidal ventilation (%I – EΔ). Results Alveoli were stable in the control group for the entire experiment (low %I – EΔ). Alveoli in the high pressure/low PEEP group were initially stable (low %I – EΔ), but with time alveolar recruitment/derecruitment developed. The development of alveolar instability in the high pressure/low PEEP group was associated with histologic lung injury. Conclusion A

  7. Comparison of Positive End-Expiratory Pressure of 8 versus 5 cm H2O on Outcome After Cardiac Operations.

    PubMed

    Hansen, Jennifer K; Anthony, David G; Li, Liang; Wheeler, David; Sessler, Daniel I; Bashour, C Allen

    2015-09-01

    Postoperative positive end-expiratory pressure (PEEP) selection in patients who are mechanically ventilated after cardiac operations often seems random. The aim of this investigation was to compare the 2 most common postoperative initial PEEP settings at our institution, 8 and 5 cm H2O, on postoperative initial tracheal intubation time (primary outcome); cardiovascular intensive care unit (CVICU); hospital length of stay (LOS); occurrence of pneumonia; and hospital mortality (secondary outcomes). The electronic medical records of patients who were mechanically ventilated after isolated coronary artery bypass grafting (CABG) or combined CABG and valve operations were reviewed. Propensity score matching was used to compare patients with an initial postoperative PEEP setting of 8 cm H2O (n = 4722 [25.9%]) with those who had PEEP of 5 cm H2O (n = 13 535 [74.1%]) on the primary and secondary outcomes listed earlier. There was no difference in initial postoperative intubation time between the PEEP of 8 cm H2O and the PEEP of 5 cm H2O patient groups (mean 11.9 vs 12.0 hours [median 8.2 vs 8.8 hours], P = .89). The groups did not differ on the occurrence of pneumonia (0.43% vs 0.60%, P = .25) nor on hospital mortality (0.47% vs 0.43%, P = .76). Aspiration pneumonia occurrence approached a significant difference (0.06% vs 0.21%, P value = .052), as did CVICU LOS (mean: 47.9 vs 49.8 hours [median: 28.5 vs 28.4 hours], P = .057), but were not statistically different. There was a slight but likely clinically unimportant difference in hospital LOS (7.7 vs 7.4 days, PEEP = 8 vs 5, P < .001). Patients being mechanically ventilated after cardiac operations with an initial postoperative PEEP setting of 8 versus 5 cm H2O differed significantly only on hospital LOS but the difference was likely clinically unimportant. Thus, use of 8 cm H2O PEEP in these patients without a clinical indication, although likely not harmful, does not seem beneficial. © The Author(s) 2014.

  8. Complex epilepsy phenotype extraction from narrative clinical discharge summaries

    PubMed Central

    Cui, Licong; Sahoo, Satya S.; Lhatoo, Samden D.; Garg, Gaurav; Rai, Prashant; Bozorgi, Alireza; Zhang, Guo-Qiang

    2015-01-01

    Epilepsy is a common serious neurological disorder with a complex set of possible phenotypes ranging from pathologic abnormalities to variations in electroencephalogram. This paper presents a system called Phenotype Exaction in Epilepsy (PEEP) for extracting complex epilepsy phenotypes and their correlated anatomical locations from clinical discharge summaries, a primary data source for this purpose. PEEP generates candidate phenotype and anatomical location pairs by embedding a named entity recognition method, based on the Epilepsy and Seizure Ontology, into the National Library of Medicine's MetaMap program. Such candidate pairs are further processed using a correlation algorithm. The derived phenotypes and correlated locations have been used for cohort identification with an integrated ontology-driven visual query interface. To evaluate the performance of PEEP, 400 de-identified discharge summaries were used for development and an additional 262 were used as test data. PEEP achieved a micro-averaged precision of 0.924, recall of 0.931, and F1-measure of 0.927 for extracting epilepsy phenotypes. The performance on the extraction of correlated phenotypes and anatomical locations shows a micro-averaged F1-measure of 0.856 (Precision: 0.852, Recall: 0.859). The evaluation demonstrates that PEEP is an effective approach to extracting complex epilepsy phenotypes for cohort identification. PMID:24973735

  9. 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.

  10. Acute response of the lung mechanics of the rabbit to hypoxia.

    PubMed

    Sakai, H; Fukui, M; Nakano, Y; Endo, K; Hirai, T; Oku, Y; Mishima, M

    1999-01-01

    We measured the change in total lung resistance (RL) and that in total lung elastance (EL) induced by hypoxia (n = 7) and compared the results with those by intravenous histamine bolus (n = 5) at three different positive end-expiratory pressure (PEEP) levels (2, 5, and 8 hPa) in open-chest and vagotomized rabbits. The percent increase ratio of RL (PIRR) and EL (PIRE) was defined as the change in RL and EL, respectively, induced by hypoxia compared with that in the normoxic condition, expressed as a percentage. PIR values for the change in RL and EL induced by bolus injection of histamine were also calculated. The PIRR and PIRE induced by hypoxia and by histamine were positive by a statistically significant amount at every PEEP level, except for the PIRE value at 8-hPa PEEP in the hypoxic challenge. The PIRE-to-PIRR ratio values in the hypoxic challenge at 2-hPa PEEP were significantly larger than those in the histamine challenge (hypoxia: 0.91 +/- 0.23%; histamine: 0.37 +/- 0. 065%, P < 0.05). The increase in EL induced by histamine in the acute phase has been reported to be mainly derived from tissue distortion secondary to bronchial constriction. Thus our results suggest that a part of the increase in EL by hypoxia was originated in different parenchymal responses from histamine and imply that this hypoxic response of lung parenchyma is sensitive to the increase in parenchymal tethering at high PEEP levels.

  11. The relationship between positive end expiratory pressure and cardiac index in patients with acute respiratory distress syndrome

    PubMed Central

    Fares, Wassim H; Carson, Shannon S

    2013-01-01

    Purpose To evaluate the association between positive end-expiratory pressure (PEEP) and cardiac index in patients with acute respiratory distress syndrome (ARDS). Methods This is a secondary cross-sectional analysis of the FACTT multi-center randomized controlled trial enrolling adult patients within 48 hours of ARDS onset. Patients randomized to the pulmonary artery catheter arm, who had PEEP and cardiac index measurements performed within a short period of each other during the first 3 days of the FACTT study enrollment were included in this study. Since FACTT had a 2×2 factorial design, half of the patients were in a ‘liberal fluids’ study arm, and the other half were in a ‘conservative fluids’ study arm. Results The final study population (833 measurements or observations, in 367 patients) was comparable to the original overall FACTT study population. The mean PEEP level used was 8.2 ± 3.4 cm H2O, and the mean cardiac index was 4.2 ± 1.2 liters/minute/m2. There was no association between PEEP and cardiac index in patients with ARDS, even when adjusted for APACHE score, age, fluid study arm in FACTT, and sepsis. Conclusion In patients with ARDS who are managed with liberal or conservative fluid management protocols, PEEP is not associated with lower cardiac index. PMID:23993772

  12. 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 H2O 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 H2O 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.

  13. 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.

  14. [Positive end-expiratory pressure : adjustment in acute lung injury].

    PubMed

    Bruells, C S; Dembinski, R

    2012-04-01

    Treatment of patients suffering from acute lung injury is a challenge for the treating physician. In recent years ventilation of patients with acute hypoxic lung injury has changed fundamentally. Besides the use of low tidal volumes, the most beneficial setting of positive end-expiratory pressure (PEEP) has been in the focus of researchers. The findings allow adaption of treatment to milder forms of acute lung injury and severe forms. Additionally computed tomography techniques to assess the pulmonary situation and recruitment potential as well as bed-side techniques to adjust PEEP on the ward have been modified and improved. This review gives an outline of recent developments in PEEP adjustment for patients suffering from acute hypoxic and hypercapnic lung injury and explains the fundamental pathophysiology necessary as a basis for correct treatment.

  15. Final postflight hardware evaluation report RSRM-32 (STS-57)

    NASA Astrophysics Data System (ADS)

    Nielson, Greg

    1993-11-01

    This document is the final report for the postflight assessment of the RSRM-32 (STS-57) flight set. This report presents the disassembly evaluations performed at the Thiokol facilities in Utah and is a continuation of the evaluations performed at KSC (TWR-64239). The PEEP for this assessment is outlined in TWR-50051, Revision B. The PEEP defines the requirements for evaluating RSRM hardware. Special hardware issues pertaining to this flight set requiring additional or modified assessment are outlined in TWR-64237. All observed hardware conditions were documented on PFOR's which are included in Appendix A. Observations were compared against limits defined in the PEEP. Any observation that was categorized as reportable or had no defined limits was documented on a preliminary PFAR by the assessment engineers. Preliminary PFAR's were reviewed by the Thiokol SPAT Executive Board to determine if elevation to PFAR's was required.

  16. Effects of stroke volume variation, pulse pressure variation, and pleth variability index in predicting fluid responsiveness during different positive end expiratory pressure in prone position.

    PubMed

    Chen, Yu; Fu, Qiang; Mi, Wei-dong

    2015-04-01

    To investigate the effects of different positive end expiratory pressures (PEEP) on functional hemodynamic parameters in patients lying in prone position during operation under general anesthesia. Totally 60 patients undergoing cervical vertebra operation or lumbar vertebra operation were studied. All patients were also monitored with Vigileo/FloTrac system. The functional hemodynamic parameters including stroke volume variation (SVV), pulse pressure variation (PPV), and pleth variability index (PVI) under PEEP levels of 0 mmHg, 5 mmHg, 10 mmHg, and 15 mmHg were recorded before and after volume expansion (hydroxyethyl starch 6%,7 ml/kg). Fluid responsiveness was defined as an increase in stroke volume index (SVI) ≥ 15%(△SVI ≥ 15%). Responders were defined as patients demonstrating an increase in SVI ≥ 15% after intravascular volume expansion and non-responders as patients whose SVI changed <15%. Receiver operating characteristic (ROC) curves were generated for SVV, PPV, and PVI under different PEEP levels to determine their diagnosis accuracies and thresholds and their potential correlations. In the prone position, SVV, PPV, and PVI were significantly higher compared to those in the supine position (P<0.05) and the mean arterial pressure significantly decreased (P<0.05); however, the changes of heart rate, stroke volume, SVI, cardiac output, and cardiac index showed no significant difference (P>0.05). In the prone position, along with the elevation of PEEP (0 mmHg, 5 mmHg, 10 mmHg, and 15 mmHg), the areas under the ROC curves of SVV were 0.864, 0.759, 0.718, and 0.521, the area under the ROC of PPV were 0.873, 0.792,0.705, and 0.505, and the area under the ROC of PVI were 0.851, 0.765 ,0.709, and 0.512. Under PEEP=0 mmHg, the diagnostic thresholds of SVV, PPV, and PVI were 10.5, 11.5, and 13.5. Under PEEP=5 mmHg, the diagnostic thresholds of SVV,PPV, and PVI were 11.5,13.5, and 14.5.Under PEEP=10 mmHg,the diagnostic thresholds of SVV, PPV, and PVI were 13

  17. Final postflight hardware evaluation report RSRM-32 (STS-57)

    NASA Technical Reports Server (NTRS)

    Nielson, Greg

    1993-01-01

    This document is the final report for the postflight assessment of the RSRM-32 (STS-57) flight set. This report presents the disassembly evaluations performed at the Thiokol facilities in Utah and is a continuation of the evaluations performed at KSC (TWR-64239). The PEEP for this assessment is outlined in TWR-50051, Revision B. The PEEP defines the requirements for evaluating RSRM hardware. Special hardware issues pertaining to this flight set requiring additional or modified assessment are outlined in TWR-64237. All observed hardware conditions were documented on PFOR's which are included in Appendix A. Observations were compared against limits defined in the PEEP. Any observation that was categorized as reportable or had no defined limits was documented on a preliminary PFAR by the assessment engineers. Preliminary PFAR's were reviewed by the Thiokol SPAT Executive Board to determine if elevation to PFAR's was required.

  18. [Comprehensive Toxicity Evaluation and Toxicity Identification Used in Tannery and Textile Wastewaters].

    PubMed

    Huang, Li; Chen, Wen-yan; Wan, Yu-shan; Zheng, Guo-juan; Zhao, Yuan; Cai, Qiang

    2015-07-01

    To better evaluate the toxicity of tannery and textile effluents from various emission stages, the research attempted battery of toxicological bioassays and toxicological indices. The bioassays employed Microtox test, zebra fish embryo-larval test and algae (Chlorella vulgaris) test. Meanwhile, toxicological indices including Toxicity Unit (TU), Average Toxicity (AvTx), Toxic Print (TxPr), Most Sensitive Test (MST) and Potential Ecotoxic Effects Probe (PEEP) were applied. The results illustrated that PEEP was the most comprehensive index to take account of the emissions and toxic potential of effluents. PEEP values showed that the reduction rates of toxicity in tannery and textile effluents were 36. 8% and 23. 2%, respectively. Finally, based on the Microtox toxicity test, toxicants in textile effluent were identified through the toxicity identification evaluation (TIE) studies. The results indicated that the main toxicant of textile effluent was non-polar organic pollutants, followed by filterable compounds, heavy metals, oxidizing substances and volatile components.

  19. Individualized positive end-expiratory pressure application in patients with acute respiratory distress syndrome.

    PubMed

    Pintado, M C; de Pablo, R

    2014-11-01

    Current treatment of acute respiratory distress syndrome is based on ventilatory support with a lung protective strategy, avoiding the development of iatrogenic injury, including ventilator-induced lung injury. One of the mechanisms underlying such injury is atelectrauma, and positive end-expiratory pressure (PEEP) is advocated in order to avoid it. The indicated PEEP level has not been defined, and in many cases is based on the patient oxygen requirements for maintaining adequate oxygenation. However, this strategy does not consider the mechanics of the respiratory system, which varies in each patient and depends on many factors-including particularly the duration of acute respiratory distress syndrome. A review is therefore made of the different methods for adjusting PEEP, focusing on the benefits of individualized application. Copyright © 2013 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

  20. Effects of Alveolar Recruitment and Positive End-Expiratory Pressure on Oxygenation during One-Lung Ventilation in the Supine Position.

    PubMed

    Choi, Yong Seon; Bae, Mi Kyung; Kim, Shin Hyung; Park, Ji-Eun; Kim, Soo Young; Oh, Young Jun

    2015-09-01

    Hypoxemia during one-lung ventilation (OLV) remains a serious problem, particularly in the supine position. We investigated the effects of alveolar recruitment (AR) and positive end-expiratory pressure (PEEP) on oxygenation during OLV in the supine position. Ninety-nine patients were randomly allocated to one of the following three groups: a control group (ventilation with a tidal volume of 8 mL/kg), a PEEP group (the same ventilatory pattern with a PEEP of 8 cm H₂O), or an AR group (an AR maneuver immediately before OLV followed by a PEEP of 8 cm H₂O). The tidal volume was reduced to 6 mL/kg during OLV in all groups. Blood gas analyses, respiratory variables, and hemodynamic variables were recorded 15 min into TLV (TLV(baseline)), 15 and 30 min after OLV (OLV₁₅ and OLV₃₀), and 10 min after re-establishing TLV (TLV(end)). Ultimately, 92 patients were analyzed. In the AR group, the arterial oxygen tension was higher at TLV(end), and the physiologic dead space was lower at OLV₁₅ and TLV(end) than in the control group. The mean airway pressure and dynamic lung compliance were higher in the PEEP and AR groups than in the control group at OLV₁₅, OLV₃₀, and TLV(end). No significant differences in hemodynamic variables were found among the three groups throughout the study period. Recruitment of both lungs with subsequent PEEP before OLV improved arterial oxygenation and ventilatory efficiency during video-assisted thoracic surgery requiring OLV in the supine position.

  1. Lung computed tomography during a lung recruitment maneuver in patients with acute lung injury.

    PubMed

    Bugedo, Guillermo; Bruhn, Alejandro; Hernández, Glenn; Rojas, Gonzalo; Varela, Cristián; Tapia, Juan Carlos; Castillo, Luis

    2003-02-01

    To assess the acute effect of a lung recruitment maneuver (LRM) on lung morphology in patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Ten patients with ALI/ARDS on mechanical ventilation. Prospective clinical study. Computed tomography (CT) scan facility in a teaching hospital. An LRM performed by stepwise increases in positive end-expiratory pressure (PEEP) of up to 30-40 cm H(2)O. Lung basal CT sections were taken at end-expiration (patients 1 to 5), and at end-expiration and end-inspiration (patients 6 to 10). Arterial blood gases and static compliance (C(st)) were measured before, during and after the LRM. Poorly aerated and non-aerated tissue at PEEP 10 cm H(2)O accounted for 60.0+/-29.1% of lung parenchyma, while only 1.1+/-1.8% was hyperinflated. Increasing PEEP to 20 and 30 cm H(2)O, compared to PEEP 10 cm H(2)O, decreased poorly aerated and non-aerated tissue by 16.2+/-28.0% and 33.4+/-13.8%, respectively ( p<0.05). This was associated with an increase in PaO(2) and a decrease in total static compliance. Inspiration increased alveolar recruitment at all PEEP levels. Hyperinflated tissue increased up to 2.9+/-4.0% with PEEP 30 cm H(2)O, and to a lesser degree with inspiration. No barotrauma or severe hypotension occurred. Lung recruitment maneuvers improve oxygenation by expanding collapsed alveoli without inducing too much hyperinflation in ALI/ARDS patients. An LRM during the CT scan gives morphologic and functional information that could be useful in setting ventilatory parameters.

  2. Regional tidal lung strain in mechanically ventilated normal lungs.

    PubMed

    Paula, Luis Felipe; Wellman, Tyler J; Winkler, Tilo; Spieth, Peter M; Güldner, Andreas; Venegas, Jose G; Gama de Abreu, Marcelo; Carvalho, Alysson R; Vidal Melo, Marcos F

    2016-12-01

    Parenchymal strain is a key determinant of lung injury produced by mechanical ventilation. However, imaging estimates of volumetric tidal strain (ε = regional tidal volume/reference volume) present substantial conceptual differences in reference volume computation and consideration of tidally recruited lung. We compared current and new methods to estimate tidal volumetric strains with computed tomography, and quantified the effect of tidal volume (VT) and positive end-expiratory pressure (PEEP) on strain estimates. Eight supine pigs were ventilated with VT = 6 and 12 ml/kg and PEEP = 0, 6, and 12 cmH2O. End-expiratory and end-inspiratory scans were analyzed in eight regions of interest along the ventral-dorsal axis. Regional reference volumes were computed at end-expiration (with/without correction of regional VT for intratidal recruitment) and at resting lung volume (PEEP = 0) corrected for intratidal and PEEP-derived recruitment. All strain estimates demonstrated vertical heterogeneity with the largest tidal strains in middependent regions (P < 0.01). Maximal strains for distinct estimates occurred at different lung regions and were differently affected by VT-PEEP conditions. Values consistent with lung injury and inflammation were reached regionally, even when global measurements were below critical levels. Strains increased with VT and were larger in middependent than in nondependent lung regions. PEEP reduced tidal-strain estimates referenced to end-expiratory lung volumes, although it did not affect strains referenced to resting lung volume. These estimates of tidal strains in normal lungs point to middependent lung regions as those at risk for ventilator-induced lung injury. The different conditions and topography at which maximal strain estimates occur allow for testing the importance of each estimate for lung injury.

  3. Effect of positive end-expiratory pressure on ductal shunting and systemic blood flow in preterm infants with patent ductus arteriosus.

    PubMed

    Fajardo, Maria Florencia; Claure, Nelson; Swaminathan, Sethuraman; Sattar, Sumbal; Vasquez, Amelia; D'Ugard, Carmen; Bancalari, Eduardo

    2014-01-01

    Left to right (L-R) shunting through a patent ductus arteriosus (PDA) can reduce systemic and cerebral blood flow in preterm infants. To minimize this, the positive end-expiratory pressure (PEEP) is often raised to increase pulmonary vascular resistance and reduce L-R shunting. The effects of this maneuver on systemic and cerebral hemodynamics and oxygenation are not well documented. To compare the effects of different PEEP on the left ventricular output (LVO), superior vena cava (SVC) flow, LVO/SVC flow ratio, cerebral oxygenation (CrSO2) and gas exchange in mechanically ventilated preterm infants with PDA. Sixteen mechanically ventilated infants of 23-30 weeks' gestational age with L-R shunting through the PDA were studied. Ultrasound measurements of LVO and SVC flow, CrSO2, arterial oxygen saturation and transcutaneous CO2 tension (TcPCO2) obtained at PEEP of 2 and 8 cm H2O were compared with baseline values at 5 cm H2O. There was a small but significant reduction in LVO and the LVO/SVC flow ratio at PEEP of 8 compared to 5 cm H2O. SVC flow and CrSO2 did not differ significantly. Increasing PEEP to 8 cm H2O in ventilated preterm infants with a PDA produced a modest decrease in L-R ductal shunting as indicated by a lower LVO/SVC flow ratio. The higher PEEP did not have a significant effect on cerebral perfusion or oxygenation. © 2013 S. Karger AG, Basel.

  4. Effects of increased positive end-expiratory pressure on intracranial pressure in acute respiratory distress syndrome: a protocol of a prospective physiological study.

    PubMed

    Chen, Han; Xu, Ming; Yang, Yan-Lin; Chen, Kai; Xu, Jing-Qing; Zhang, Ying-Rui; Yu, Rong-Guo; Zhou, Jian-Xin

    2016-11-15

    There are concerns that the use of positive end-expiratory pressure (PEEP) in patients with brain injury may potentially elevate intracranial pressure (ICP). However, the transmission of PEEP into the thoracic cavity depends on the properties of the lungs and the chest wall. When chest wall elastance is high, PEEP can significantly increase pleural pressure. In the present study, we investigate the different effects of PEEP on the pleural pressure and ICP in different respiratory mechanics. This study is a prospective, single-centre, physiological study in patients with severe brain injury. Patients with acute respiratory distress syndrome with ventricular drainage will be enrolled. An oesophageal balloon catheter will be inserted to measure oesophageal pressure. Patients will be sedated and paralysed; airway pressure and oesophageal pressure will be measured during end-inspiratory occlusion and end-expiratory occlusion. Elastance of the chest wall, the lungs and the respiratory system will be calculated at PEEP levels of 5, 10 and 15 cm H2O. We will classify each patient based on the maximal ΔICP/ΔPEEP being above or below the median for the study population. 2 groups will thus be compared. The study protocol and consent forms were approved by the Institutional Review Board of Fujian Provincial Hospital. Study findings will be disseminated through peer-reviewed publications and conference presentations. NCT02670733; pre-results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  5. Plasma-derived human C1-esterase inhibitor does not prevent mechanical ventilation-induced pulmonary complement activation in a rat model of Streptococcus pneumoniae pneumonia.

    PubMed

    de Beer, F M; Aslami, H; Hoeksma, J; van Mierlo, G; Wouters, D; Zeerleder, S; Roelofs, J J T H; Juffermans, N P; Schultz, M J; Lagrand, W K

    2014-11-01

    Mechanical ventilation has the potential to cause lung injury, and the role of complement activation herein is uncertain. We hypothesized that inhibition of the complement cascade by administration of plasma-derived human C1-esterase inhibitor (C1-INH) prevents ventilation-induced pulmonary complement activation, and as such attenuates lung inflammation and lung injury in a rat model of Streptococcus pneumoniae pneumonia. Forty hours after intratracheal challenge with S. pneumoniae causing pneumonia rats were subjected to ventilation with lower tidal volumes and positive end-expiratory pressure (PEEP) or high tidal volumes without PEEP, after an intravenous bolus of C1-INH (200 U/kg) or placebo (saline). After 4 h of ventilation blood, broncho-alveolar lavage fluid and lung tissue were collected. Non-ventilated rats with S. pneumoniae pneumonia served as controls. While ventilation with lower tidal volumes and PEEP slightly amplified pneumonia-induced complement activation in the lungs, ventilation with higher tidal volumes without PEEP augmented local complement activation more strongly. Systemic pre-treatment with C1-INH, however, failed to alter ventilation-induced complement activation with both ventilation strategies. In accordance, lung inflammation and lung injury were not affected by pre-treatment with C1-INH, neither in rats ventilated with lower tidal volumes and PEEP, nor rats ventilated with high tidal volumes without PEEP. Ventilation augments pulmonary complement activation in a rat model of S. pneumoniae pneumonia. Systemic administration of C1-INH, however, does not attenuate ventilation-induced complement activation, lung inflammation, and lung injury.

  6. The effect of positive end-expiratory pressure on inflammatory cytokines during laparoscopic cholecystectomy

    PubMed Central

    Yılmazlar, Firdevs; Karabayırlı, Safinaz; Gözdemir, Muhammet; Usta, Burhanettin; Peker, Murat; Namuslu, Mehmet; Erdamar, Hüsamettin

    2015-01-01

    Objectives: To investigate effects of the positive end-expiratory pressure (PEEP) application of 10 cm H2O on the plasma levels of cytokines during laparoscopic cholecystectomy. Methods: A prospective study was conducted on 40 patients who presented to the Department of General Surgery, Medical Faculty, Turgut Özal University, Ankara, Turkey scheduled for laparoscopic cholecystectomy operation during a 10 month period from September 2012 to June 2013. Forty patients scheduled for laparoscopic cholecystectomy operation were randomly divided into 2 groups; ventilation through zero end-expiratory pressure (ZEEP) (0 cm H2O PEEP) (n=20), and PEEP (10 cm H2O PEEP) (n=20). All patients were ventilated with 8 ml/kg TV. Levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL 10, and transforming growth factor (TGF)-β1 were measured in the pre- and post-operatively collected samples. Results: Blood samples of 30 patients’ were analyzed for plasma cytokine levels, and 10 were excluded from the study due to hemolysis. Post-operative plasma IL-6 levels were observed to be significantly higher than the pre-operative patients (p=0.035). Post-operative plasma TGF-β1 levels in the PEEP group was found significantly higher compared with the pre-operative group levels (p=0.033). However, there were no significant differences in the pre- and post-operative plasma cytokine levels between the 2 groups. Conclusion: The application of PEEP of 10 cm H2O, which has known beneficial effect on respiratory mechanics, does not have any effect on systemic inflammatory response undergoing pneumoperitoneum during laparoscopic cholecystectomy surgery. PMID:26593173

  7. Role of nasal positive end expiratory pressure valve as an alternative treatment for obstructive sleep apnoea in Chinese patients.

    PubMed

    To, Kin Wang; Chan, Tat O; Ng, Susana; Ngai, Jenny; Hui, David Sc

    2016-04-01

    As compliance of continuous positive airway pressure (CPAP) for treatment of obstructive sleep apnoea (OSA) is often suboptimal, a less cumbersome treatment is desirable. We explored the clinical usefulness of nasal positive end expiratory pressure (nPEEP) valves. Symptomatic OSA patients (apnoea hypopnea index (AHI) >5/h by polysomnography (PSG) or >10/h by type III devices), who declined CPAP, were recruited. A nPEEP valve was attached to each nostril before bed. After successful acclimatization for 1 week, treatment was continued for 4 weeks. The nPEEP valves provided expiratory resistance to build up PEEP. PSG was performed at week 4. Among 196 subjects, 46 (23%) failed acclimatization and 14 (7%) withdrew. Among the 120 patients with a valid PSG, 72 (60%) and 75 (63%) had >50% reduction in mean (standard deviation) overall AHI 26 (16)/h to 18 (18)/h and mean supine AHI 31 (19)/h to 11(16)/h, respectively, P < 0.001. Compared with responders, patients with <50% reduction in AHI had a higher mean overall AHI (30/h vs 23/h, P = 0.03), higher mean supine AHI (35/h vs 26/h, P = 0.04), more severe mean oxygen desaturation nadir (76.7% vs 82.7%, P < 0.01) and longer mean period of desaturation <90% SaO2 (7.7 vs 2.4, P = 0.02). Breathing discomfort and dry mouth were the most common side effects. Compared with a dental device, there was a larger mean reduction in supine AHI using nPEEP (29 (14)/h vs 16 (17)/h). nPEEP valves were useful in selected patients with mild or positional-related OSA. © 2015 Asian Pacific Society of Respirology.

  8. Influence of respiratory pressure support on hemodynamics and exercise tolerance in patients with COPD.

    PubMed

    Oliveira, Cristino Carneiro; Carrascosa, Cláudia Regina; Borghi-Silva, Audrey; Berton, Danilo C; Queiroga, Fernando; Ferreira, Eloara M V; Nery, Luiz E; Neder, J Alberto; Alberto Neder, J

    2010-07-01

    Inspiratory pressure support (IPS) plus positive end-expiratory pressure (PEEP) ventilation might potentially interfere with the "central" hemodynamic adjustments to exercise in patients with chronic obstructive pulmonary disease (COPD). Twenty-one non- or mildly-hypoxemic males (FEV(1) = 40.1 +/- 10.7% predicted) were randomly assigned to IPS (16 cmH(2)O) + PEEP (5 cmH(2)O) or spontaneous ventilation during constant-work rate (70-80% peak) exercise tests to the limit of tolerance (T (lim)). Heart rate (HR), stroke volume (SV), and cardiac output (CO) were monitored by transthoracic cardioimpedance (Physioflow, Manatec, France). Oxyhemoglobin saturation was assessed by pulse oximetry (SpO(2)). At similar SpO(2), IPS(16) + PEEP(5) was associated with heterogeneous cardiovascular effects compared with the control trial. Therefore, 11 patients (Group A) showed stable or increased Delta "isotime" - rest SV [5 (0-29) mL], lower DeltaHR but similar DeltaCO. On the other hand, DeltaSV [-10 (-15 to -3) mL] and DeltaHR were both lower with IPS(16) + PEEP(5) in Group B (N = 10), thereby reducing DeltaCO (p < 0.05). Group B showed higher resting lung volumes, and T (lim) improved with IPS(16) + PEEP(5) only in Group A [51 (-60 to 486) vs. 115 (-210 to 909) s, respectively; p < 0.05]. We conclude that IPS(16) + PEEP(5) may improve SV and exercise tolerance in selected patients with advanced COPD. Impaired SV and CO responses, associated with a lack of enhancement in exercise capacity, were found in a sub-group of patients who were particularly hyperinflated at rest.

  9. Effects of reduced tidal volume ventilation on pulmonary function in mice before and after acute lung injury.

    PubMed

    Thammanomai, Apiradee; Majumdar, Arnab; Bartolák-Suki, Erzsébet; Suki, Béla

    2007-11-01

    We investigated the influence of load impedance on ventilator performance and the resulting effects of reduced tidal volume (Vt) on lung physiology during a 30-min ventilation of normal mice and 10 min of additional ventilation following lavage-induced injury at two positive end-expiratory pressure (PEEP) levels. Respiratory mechanics were regularly monitored, and the lavage fluid was tested for the soluble E-cadherin, an epithelial cell adhesion molecule, and surfactant protein (SP) B. The results showed that, due to the load dependence of the delivered Vt from the small-animal ventilator: 1) uncontrolled ventilation in normal mice resulted in a lower delivered Vt (6 ml/kg at 3-cmH(2)O PEEP and 7 ml/kg at 6-cmH(2)O PEEP) than the prescribed Vt (8 ml/kg); 2) at 3-cmH(2)O PEEP, uncontrolled ventilation in normal mice led to an increase in lung parenchymal functional heterogeneity, a reduction of SP-B, and an increase in E-cadherin; 3) at 6-cmH(2)O PEEP, ventilation mode had less influence on these parameters; and 4) in a lavage model of acute respiratory distress syndrome, delivered Vt decreased to 4 ml/kg from the prescribed 8 ml/kg, which resulted in severely compromised lung function characterized by increases in lung elastance, airway resistance, and alveolar tissue heterogeneity. Furthermore, the low Vt ventilation also resulted in poor survival rate independent of PEEP. These results highlight the importance of delivering appropriate Vt to both the normal and injured lungs. By leaving the Vt uncompensated, it can significantly alter physiological and biological responses in mice.

  10. Correlation between extravascular lung water and oxygenation in ALI/ARDS patients in septic shock: possible role in the development of atelectasis?

    PubMed

    Szakmany, T; Heigl, P; Molnar, Z

    2004-04-01

    This study aimed to evaluate the relationship between PaO2/FiO2 ratio and extravascular lung water in septic shock-induced acute respiratory distress syndrome in a prospective observational clinical trial. Twenty-three patients suffering from sepsis induced acute respiratory distress syndrome were recruited. All patients were ventilated in pressure control/support mode. Haemodynamic parameters were determined by arterial thermodilution (PiCCO) eight hourly for 72 hours. At the same time blood gas analyses were done and respiratory parameters were also recorded. Data are presented as mean +/-SD. For statistical analysis Pearson's correlation test, and analysis of variance (ANOVA) was used respectively. Significant negative correlation was found between extravascular lung water and PaO2/FiO2 (r = -0.355, P < 0.001), and significant positive correlation was shown between extravascular lung water and PEEP (r=0.557, P<0.001). A post-hoc analysis was performed when "low" PEEP: < 10 cmH2O and "high" PEEP: (10 cmH2O PEEP was applied, and neither the oxygenation, nor the driving pressure or the PaCO2 differed significantly, but the extravascular lung water showed significant difference when "high" or "low" PEEP was applied (13+/-5 vs 9+/-2 ml/kg respectively, P=0.001). This study found significant negative correlation between extravascular lung water and PaO2/FiO2. The mechanism by which extravascular lung water affects oxygenation is unknown but the significant positive correlation between PEEP and extravascular lung water shown in this trial suggests that the latter may have a role in the development of alveolar atelectasis.

  11. Prevention of atelectasis in morbidly obese patients during general anesthesia and paralysis: a computerized tomography study.

    PubMed

    Reinius, Henrik; Jonsson, Lennart; Gustafsson, Sven; Sundbom, Magnus; Duvernoy, Olov; Pelosi, Paolo; Hedenstierna, Göran; Fredén, Filip

    2009-11-01

    Morbidly obese patients show impaired pulmonary function during anesthesia and paralysis, partly due to formation of atelectasis. This study analyzed the effect of general anesthesia and three different ventilatory strategies to reduce the amount of atelectasis and improve respiratory function. Thirty patients (body mass index 45 +/- 4 kg/m) scheduled for gastric bypass surgery were prospectively randomized into three groups: (1) positive end-expiratory pressure of 10 cm H2O (PEEP), (2) a recruitment maneuver with 55 cm H2O for 10 s followed by zero end-expiratory pressure, (3) a recruitment maneuver followed by PEEP. Transverse lung computerized tomography scans and blood gas analysis were recorded: awake, 5 min after induction of anesthesia and paralysis at zero end-expiratory pressure, and 5 min and 20 min after intervention. In addition, spiral computerized tomography scans were performed at two occasions in 23 of the patients. After induction of anesthesia, atelectasis increased from 1 +/- 0.5% to 11 +/- 6% of total lung volume (P < 0.0001). End-expiratory lung volume decreased from 1,387 +/- 581 ml to 697 +/- 157 ml (P = 0.0014). A recruitment maneuver + PEEP reduced atelectasis to 3 +/- 4% (P = 0.0002), increased end-expiratory lung volume and increased Pao2/Fio2 from 266 +/- 70 mmHg to 412 +/- 99 mmHg (P < 0.0001). PEEP alone did not reduce the amount of atelectasis or improve oxygenation. A recruitment maneuver + zero end-expiratory pressure had a transient positive effect on respiratory function. All values are presented as mean +/- SD. A recruitment maneuver followed by PEEP reduced atelectasis and improved oxygenation in morbidly obese patients, whereas PEEP or a recruitment maneuver alone did not.

  12. Comparison of static end-expiratory and effective lung volumes for gas exchange in healthy and surfactant-depleted lungs.

    PubMed

    Albu, Gergely; Wallin, Mats; Hallbäck, Magnus; Emtell, Per; Wolf, Andrew; Lönnqvist, Per-Arne; Göthberg, Sylvia; Peták, Ferenc; Habre, Walid

    2013-07-01

    Effective lung volume (ELV) for gas exchange is a new measure that could be used as a real-time guide during controlled mechanical ventilation. The authors established the relationships of ELV to static end-expiratory lung volume (EELV) with varying levels of positive end-expiratory pressure (PEEP) in healthy and surfactant-depleted rabbit lungs. Nine rabbits were anesthetized and ventilated with a modified volume-controlled mode where periods of five consecutive alterations in inspiratory/expiratory ratio (1:2-1.5:1) were imposed to measure ELV from the corresponding carbon dioxide elimination traces. EELV and the lung clearance index were concomitantly determined by helium wash-out technique. Airway and tissue mechanics were assessed by using low-frequency forced oscillations. Measurements were collected at PEEP 0, 3, 6, and 9 cm H2O levels under control condition and after surfactant depletion by whole-lung lavage. ELV was greater than EELV at all PEEP levels before lavage, whereas there was no evidence for a difference in the lung volume indices after surfactant depletion at PEEP 6 or 9 cm H2O. Increasing PEEP level caused significant parallel increases in both ELV and EELV levels, decreases in ventilation heterogeneity, and improvement in airway and tissue mechanics under control condition and after surfactant depletion. ELV and EELV exhibited strong and statistically significant correlations before (r=0.84) and after lavage (r=0.87). The parallel changes in ELV and EELV with PEEP in healthy and surfactant-depleted lungs support the clinical value of ELV measurement as a bedside tool to estimate dynamic changes in EELV in children and infants.

  13. Compliance-guided versus FiO2-driven positive-end expiratory pressure in patients with moderate or severe acute respiratory distress syndrome according to the Berlin definition.

    PubMed

    Pintado, M-C; de Pablo, R; Trascasa, M; Milicua, J-M; Sánchez-García, M

    To study the effect of setting positive end-expiratory pressure (PEEP) in an individualized manner (based on highest static compliance) compared to setting PEEP according to FiO2 upon mortality at 28 and 90 days, in patients with different severity acute respiratory distress syndrome (ARDS). A Spanish medical-surgical ICU. A post hoc analysis of a randomized controlled pilot study. Patients with ARDS. Ventilation with low tidal volumes and pressure limitation at 30cmH2O, randomized in two groups according to the method used to set PEEP: FiO2-guided PEEP group according to FiO2 applied and compliance-guided group according to the highest compliance. Demographic data, risk factors and severity of ARDS, APACHE II and SOFA scores, daily Lung Injury Score, ventilatory measurements, ICU and hospital stay, organ failure and mortality at day 28 and 90 after inclusion. A total of 159 patients with ARDS were evaluated, but just 70 patients were included. Severe ARDS patients showed more organ dysfunction-free days at 28 days (12.83±10.70 versus 3.09±7.23; p=0.04) and at 90 days (6.73±22.31 vs. 54.17±42.14, p=0.03), and a trend toward lower 90-days mortality (33.3% vs. 90.9%, p=0.02), when PEEP was applied according to the best static compliance. Patients with moderate ARDS did not show these effects. In patients with severe ARDS, individualized PEEP selection based on the best static compliance was associated to lower mortality at 90 days, with an increase in organ dysfunction-free days at 28 and 90 days. Copyright © 2016 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

  14. A clinical classification of the acute respiratory distress syndrome for predicting outcome and guiding medical therapy*.

    PubMed

    Villar, Jesús; Fernández, Rosa L; Ambrós, Alfonso; Parra, Laura; Blanco, Jesús; Domínguez-Berrot, Ana M; Gutiérrez, José M; Blanch, Lluís; Añón, José M; Martín, Carmen; Prieto, Francisca; Collado, Javier; Pérez-Méndez, Lina; Kacmarek, Robert M

    2015-02-01

    Current in-hospital mortality of the acute respiratory distress syndrome (ARDS) is above 40%. ARDS outcome depends on the lung injury severity within the first 24 hours of ARDS onset. We investigated whether two widely accepted cutoff values of PaO2/FIO2 and positive end-expiratory pressure (PEEP) would identify subsets of patients with ARDS for predicting outcome and guiding therapy. A 16-month (September 2008 to January 2010) prospective, multicenter, observational study. Seventeen multidisciplinary ICUs in Spain. We studied 300 consecutive, mechanically ventilated patients meeting American-European Consensus Conference criteria for ARDS (PaO2/FIO2 ≤ 200 mm Hg) on PEEP greater than or equal to 5 cm H2O, and followed up until hospital discharge. None. Based on threshold values for PaO2/FIO2 (150 mm Hg) and PEEP (10 cm H2O) at ARDS onset and at 24 hours, we assigned patients to four categories: group I (PaO2/FIO2 ≥ 150 on PEEP < 10), group II (PaO2/FIO2 ≥ 150 on PEEP ≥ 10), group III (PaO2/FIO2 < 150 on PEEP < 10), and group IV (PaO2/FIO2 < 150 on PEEP ≥ 10). The primary outcome was all-cause in-hospital mortality. Overall hospital mortality was 46.3%. Although at study entry, patients with PaO2/FIO2 less than 150 had a higher mortality than patients with a PaO2/FIO2 greater than or equal to 150 (p = 0.044), there was minimal variability in mortality among the four groups (p = 0.186). However, classification of patients in each group changed markedly after 24 hours of usual care. Group categorization at 24 hours provided a strong association with in-hospital mortality (p < 0.00001): group I had the lowest mortality (23.1%), whereas group IV had the highest mortality (60.3%). The degree of lung dysfunction established by a PaO2/FIO2 of 150 mm Hg and a PEEP of 10 cm H2O demonstrated that ARDS is not a homogeneous disorder. Rather, it is a series of four subsets that should be considered for enrollment in clinical trials and for guiding therapy. A major

  15. The effect of alveolar dead space on the measurement of end-expiratory lung volume by modified nitrogen wash-out/wash-in in lavage-induced lung injury.

    PubMed

    Tang, Rui; Huang, Yingzi; Chen, Qiuhua; Hui, Xia; Li, Yang; Yu, Qing; Zhao, Hongjie; Yang, Yi; Qiu, Haibo

    2012-12-01

    The accuracy of end-expiratory lung volume measurement by the modified nitrogen wash-out/wash-in method (EELV-N(2)) depends on the precise determination of carbon dioxide elimination (V(CO(2))), which is affected by alveolar dead space (V(D-alv)). The purpose of this study was to investigate the influence of V(D-alv) on EELV-N(2). Six piglets with lavage-induced acute lung injury were mechanically ventilated in a decremental PEEP trial that was reduced from 20 to 4 cm H(2)O in steps of 4 cm H(2)O every 10 min. EELV was measured by the modified EELV-N(2) method and computed tomography scan (EELV-CT), volumetric capnography, blood gas measurements, and hemodynamic data were recorded at each PEEP level. The data were divided into higher and lower PEEP groups. During the decremental PEEP trial, EELV-N(2) exhibited a high correlation (r(2) = 0.86, P < .001) with EELV-CT, with a bias of -48.6 ± 150.7 mL (1 ± 18%). In the higher PEEP group, EELV-N(2) was not correlated with EELV-CT, with a bias of -168.1 ± 171.5 mL (-14 ± 14%). However, in the lower PEEP group, EELV-N(2) exhibited a high correlation (r(2) = 0.86, P < .001) with EELV-CT, with a bias of 11.2 ± 97.2 mL (6 ± 17%). The measurement bias was negatively correlated with V(D-alv) (r(2) = 0.44, P = .04) and V(CO(2)) (r(2) = 0.47, P = .03) in the higher PEEP group. In this surfactant-depleted model, EELV measurement by the modified EELV-N(2) method reveals a systematic underestimation at high PEEP levels that is partly due to an increase in V(D-alv).

  16. Modification of a nonrebreathing circuit adapter to prevent barotrauma in anesthetized patients.

    PubMed

    McMurphy, R M; Hodgson, D S; Cribb, P H

    1995-01-01

    Barotrauma, pneumothorax, and pneumomediastinum occurred in two anesthetized cats in which the waste gas outlet of a nonrebreathing circuit was occluded. To prevent any similar cases of barotrauma, we have modified our nonrebreathing circuit adapters by inserting a 15 cm H2O PEEP valve into the gas pathway of the nonrebreathing circuit adapter. This PEEP valve prevents the circuit and airway pressures from exceeding 15 cm H2O if the pop-off valve of the nonrebreathing circuit adapter is inadvertently left closed.

  17. Invasive mechanical ventilation as a risk factor for acute kidney injury in the critically ill: a systematic review and meta-analysis.

    PubMed

    van den Akker, Johannes P C; Egal, Mahamud; Groeneveld, A B Johan

    2013-05-27

    Mechanical ventilation (MV) is commonly regarded as a risk factor for acute kidney injury (AKI) in the critically ill. We investigated the strength of this association and whether settings of tidal volume (Vt) and positive end-expiratory pressure (PEEP) affect the risk for AKI. We performed a systematic review and meta-analysis using studies found by searching MEDLINE, EMBASE, and references in relevant reviews and articles. We included studies reporting on a relation between the use of invasive MV and subsequent onset of AKI, or comparing higher with lower Vt or PEEP and subsequent onset of AKI. All studies clearly stating that MV was initiated after onset of AKI were excluded. We extracted the proportion with and without MV and AKI. We included 31 studies on invasive MV. The pooled odds ratio (OR) for the overall effect of MV on AKI was 3.16 (95% CI 2.32 to 4.28, P<0.001). Nearly all subgroups showed that MV increases the risk for AKI. The pooled OR for studies with a multivariate analysis including MV as a risk factor for AKI was 3.58 (95% CI 1.85 to 6.92; P<0.001). Different settings of Vt and PEEP showed no effect. Invasive MV is associated with a threefold increase in the odds of developing AKI and various Vt or PEEP settings do not modify this risk. The latter argues in favour of a haemodynamic origin of AKI during MV.

  18. Early Phonological Development: Creating an Assessment Test

    ERIC Educational Resources Information Center

    Stoel-Gammon, Carol; Williams, A. Lynn

    2013-01-01

    This paper describes a new protocol for assessing the phonological systems of two-year-olds with typical development and older children with delays in vocabulary acquisition. The test (Profiles of Early Expressive Phonological Skills ("PEEPS"), Williams & Stoel-Gammon, in preparation) differs from currently available assessments in…

  19. Comparison of a phospholipid-based protein-free surfactant and a natural bovine surfactant (SURVANTA) during pressure and volume-controlled ventilation in an improved rabbit fetus model.

    PubMed

    Häfner, D; Kilian, U; Bühler, R; Beume, R; Habel, R

    1993-03-01

    During pressure- or volume-controlled ventilation different surfactant preparations were compared in an improved rabbit fetus model. Based on a self-designed software program, this model enables on-line registration of lung mechanics and heart rate in up to ten fetuses. Using a commercially available bovine lung surfactant (SURVANTA) as standard, we compared animals treated with a protein-free surfactant preparation containing only phospholipids, PL (dipalmitoylphosphatidylcholine:palmitoyloleoylphosphatidylglycerol++ +, DPPC:POPG 70:30) plus palmitic acid (PA) with an untreated ventilated control group. During pressure-controlled ventilation the insufflation pressure (IP) was decreased and increased stepwise with and without positive end-expiratory pressure (PEEP). SURVANTA was significantly more potent than PL plus PA and both differed significantly from the untreated controls. With additional PEEP the differences between SURVANTA and PL+PA disappeared but the differences to the controls were still present. We found that, with additional PEEP, active natural surfactants lead to ECG-irregularities, which indicates that PEEP influences pulmonary and cardiovascular function and compromises the benefits of surfactant therapy. Also during volume-controlled ventilation SURVANTA was superior to PL+PA and the untreated controls. In order to raise the level of activity of pure PL mixtures to that of natural bovine surfactants, we suggest that a surface active protein (probably SP-C) must be added to such mixtures.

  20. Effects of respiratory rate, plateau pressure, and positive end-expiratory pressure on PaO2 oscillations after saline lavage.

    PubMed

    Baumgardner, James E; Markstaller, Klaus; Pfeiffer, Birgit; Doebrich, Marcus; Otto, Cynthia M

    2002-12-15

    One of the proposed mechanisms of ventilator-associated lung injury is cyclic recruitment of atelectasis. Collapse of dependent lung regions with every breath should lead to large oscillations in PaO2 as shunt varies throughout the respiratory cycle. We placed a fluorescence-quenching PO2 probe in the brachiocephalic artery of six anesthetized rabbits after saline lavage. Using pressure-controlled ventilation with oxygen, ventilator settings were varied in random order over three levels of positive end-expiratory pressure (PEEP), respiratory rate (RR), and plateau pressure minus PEEP (Delta). Dependence of the amplitude of PaO2 oscillations on PEEP, RR, and Delta was modeled by multiple linear regression. Before lavage, arterial PO2 oscillations varied from 3 to 22 mm Hg. After lavage, arterial PO2 oscillations varied from 5 to 439 mm Hg. Response surfaces showed markedly nonlinear dependence of amplitude on PEEP, RR, and Delta. The large PaO2 oscillations observed provide evidence for cyclic recruitment in this model of lung injury. The important effect of RR on the magnitude of PaO2 oscillations suggests that the static behavior of atelectasis cannot be accurately extrapolated to predict dynamic behavior at realistic breathing frequencies.

  1. Piedmont Export Expansion Program Monograph: A Final Report.

    ERIC Educational Resources Information Center

    Brown, Ralph W., Jr.; Peniche, Eduardo A.

    The Piedmont Export Expansion Program (PEEP) was developed to increase the number of businesses in central Virginia entering or expanding export trade; to increase the utilization of the services of Central Virginia Community College's (CVCC's) Cross-Cultural and Foreign Language Resource Center by area export businesses; to increase the number of…

  2. In vivo microscopy in a porcine model of acute lung injury.

    PubMed

    Bickenbach, Johannes; Czaplik, Michael; Dembinski, Rolf; Pelosi, Paolo; Schroeder, Wolfgang; Marx, Gernot; Rossaint, Rolf

    2010-07-31

    Regional inhomogeneity and alveolar mechanics in a porcine model of acute lung injury (ALI) was evaluated using confocal laser scanning microscopy (CLSM). CLSM was performed through thoracic windows of the upper and lower lobes. Image quantification was conducted by use of a volume air index (VAI). Twelve anesthetized, mechanically ventilated pigs were randomized to non-injury (control group, n = 6) or ALI induced by surfactant depletion (ALI group, n = 6). CLSM was performed at baseline, after 1 h at 5 mbar and after 2 h at 15 mbar positive end-expiratory pressure (PEEP). Haemodynamics, respiratory mechanics and calculation of pulmonary ventilation-perfusion distribution by MIGET were determined. At baseline, VAI was not different. In the upper lobes, VAI significantly decreased in ALI compared to control group, with no changes after PEEP application. In the lower lobes, VAI significantly decreased in ALI compared to control group. Incremental PEEP significantly increased VAI in ALI, but not in control group. Haemodynamics were significantly compromised in the ALI group. A significant deterioration in oxygenation and ventilation-perfusion distribution could be seen being restored after PEEP adjustment. The VAI may help to assess regional inhomogeneity of the acutely injured lung.

  3. Piedmont Export Expansion Program Monograph: A Final Report.

    ERIC Educational Resources Information Center

    Brown, Ralph W., Jr.; Peniche, Eduardo A.

    The Piedmont Export Expansion Program (PEEP) was developed to increase the number of businesses in central Virginia entering or expanding export trade; to increase the utilization of the services of Central Virginia Community College's (CVCC's) Cross-Cultural and Foreign Language Resource Center by area export businesses; to increase the number of…

  4. Early Phonological Development: Creating an Assessment Test

    ERIC Educational Resources Information Center

    Stoel-Gammon, Carol; Williams, A. Lynn

    2013-01-01

    This paper describes a new protocol for assessing the phonological systems of two-year-olds with typical development and older children with delays in vocabulary acquisition. The test (Profiles of Early Expressive Phonological Skills ("PEEPS"), Williams & Stoel-Gammon, in preparation) differs from currently available assessments in…

  5. Effects of Lung Expansion Therapy on Lung Function in Patients with Prolonged Mechanical Ventilation.

    PubMed

    Chen, Yen-Huey; Yeh, Ming-Chu; Hu, Han-Chung; Lee, Chung-Shu; Li, Li-Fu; Chen, Ning-Hung; Huang, Chung-Chi; Kao, Kuo-Chin

    2016-01-01

    Common complications in PMV include changes in the airway clearance mechanism, pulmonary function, and respiratory muscle strength, as well as chest radiological changes such as atelectasis. Lung expansion therapy which includes IPPB and PEEP prevents and treats pulmonary atelectasis and improves lung compliance. Our study presented that patients with PMV have improvements in lung volume and oxygenation after receiving IPPB therapy. The combination of IPPB and PEEP therapy also results in increase in respiratory muscle strength. The application of IPPB facilitates the homogeneous gas distribution in the lung and results in recruitment of collapsed alveoli. PEEP therapy may reduce risk of respiratory muscle fatigue by preventing premature airway collapse during expiration. The physiologic effects of IPPB and PEEP may result in enhancement of pulmonary function and thus increase the possibility of successful weaning from mechanical ventilator during weaning process. For patients with PMV who were under the risk of atelectasis, the application of IPPB may be considered as a supplement therapy for the enhancement of weaning outcome during their stay in the hospital.

  6. Effects of Lung Expansion Therapy on Lung Function in Patients with Prolonged Mechanical Ventilation

    PubMed Central

    Chen, Yen-Huey; Yeh, Ming-Chu; Hu, Han-Chung; Lee, Chung-Shu; Li, Li-Fu; Chen, Ning-Hung; Huang, Chung-Chi; Kao, Kuo-Chin

    2016-01-01

    Common complications in PMV include changes in the airway clearance mechanism, pulmonary function, and respiratory muscle strength, as well as chest radiological changes such as atelectasis. Lung expansion therapy which includes IPPB and PEEP prevents and treats pulmonary atelectasis and improves lung compliance. Our study presented that patients with PMV have improvements in lung volume and oxygenation after receiving IPPB therapy. The combination of IPPB and PEEP therapy also results in increase in respiratory muscle strength. The application of IPPB facilitates the homogeneous gas distribution in the lung and results in recruitment of collapsed alveoli. PEEP therapy may reduce risk of respiratory muscle fatigue by preventing premature airway collapse during expiration. The physiologic effects of IPPB and PEEP may result in enhancement of pulmonary function and thus increase the possibility of successful weaning from mechanical ventilator during weaning process. For patients with PMV who were under the risk of atelectasis, the application of IPPB may be considered as a supplement therapy for the enhancement of weaning outcome during their stay in the hospital. PMID:27445550

  7. Intraoperative ventilatory strategies for prevention of pulmonary atelectasis in obese patients undergoing laparoscopic bariatric surgery.

    PubMed

    Talab, Hesham F; Zabani, Ibrahim Ali; Abdelrahman, Hassan Saad; Bukhari, Waleed L; Mamoun, Irfan; Ashour, Majed A; Sadeq, Bakr Bin; El Sayed, Sameh Ibrahim

    2009-11-01

    Atelectasis occurs regularly after induction of general anesthesia, persists postoperatively, and may contribute to significant postoperative morbidity and additional health care costs. Laparoscopic surgery has been reported to be associated with an increased incidence of postoperative atelectasis. It has been shown that during general anesthesia, obese patients have a greater risk of atelectasis than nonobese patients. Preventing atelectasis is important for all patients but is especially important when caring for obese patients. We randomly allocated 66 adult obese patients with a body mass index between 30 and 50 kg/m(2) scheduled to undergo laparoscopic bariatric surgery into 3 groups. According to the recruitment maneuver used, the zero end-expiratory pressure (ZEEP) group (n = 22) received the vital capacity maneuver (VCM) maintained for 7-8 s applied immediately after intubation plus ZEEP; the positive end-expiratory pressure (PEEP) 5 group (n = 22) received the VCM maintained for 7-8 s applied immediately after intubation plus 5 cm H(2)O of PEEP; and the PEEP 10 group (n = 22) received the VCM maintained for 7-8 s applied immediately after intubation plus 10 cm H(2)O of PEEP. All other variables (e.g., anesthetic and surgical techniques) were the same for all patients. Heart rate, noninvasive mean arterial blood pressure, arterial oxygen saturation, and alveolar-arterial Pao(2) gradient (A-a Pao(2)) were measured intraoperatively and postoperatively in the postanesthesia care unit (PACU). Length of stay in the PACU and the use of a nonrebreathing O(2) mask (100% Fio(2)) or reintubation were also recorded. A computed tomographic scan of the chest was performed preoperatively and postoperatively after discharge from the PACU to evaluate lung atelectasis. Patients in the PEEP 10 group had better oxygenation both intraoperatively and postoperatively in the PACU, lower atelectasis score on chest computed tomographic scan, and less postoperative pulmonary

  8. Current ventilation practice during general anaesthesia: a prospective audit in Melbourne, Australia.

    PubMed

    Karalapillai, Dharshi; Weinberg, Laurence; Galtieri, Jonathan; Glassford, Neil; Eastwood, Glenn; Darvall, Jai; Geertsema, Jake; Bangia, Ravi; Fitzgerald, Jane; Phan, Tuong; OHallaran, Luke; Cocciante, Adriano; Watson, Stuart; Story, David; Bellomo, Rinaldo

    2014-01-01

    Recent evidence suggests that the use of low tidal volume ventilation with the application of positive end-expiratory pressure (PEEP) may benefit patients at risk of respiratory complications during general anaesthesia. However current Australian practice in this area is unknown. To describe current practice of intraoperative ventilation with regard to tidal volume and application of PEEP, we performed a multicentre audit in patients undergoing general anaesthesia across eight teaching hospitals in Melbourne, Australia. We obtained information including demographic characteristics, type of surgery, tidal volume and the use of PEEP in a consecutive cohort of 272 patients. The median age was 56 (IQR 42-69) years; 150 (55%) were male. Most common diagnostic groups were general surgery (31%), orthopaedic surgery (20%) and neurosurgery (9.6%). Mean FiO2 was 0.6 (IQR 0.5-0.7). Median tidal volume was 500 ml (IQR 450-550). PEEP was used in 54% of patients with a median value of 5.0 cmH2O (IQR 4.0-5.0) and median tidal volume corrected for predicted body weight was 9.5 ml/kg (IQR 8.5-10.4). Median peak inspiratory pressure was 18 cmH2O (IQR 15-22). In a cohort of patients considered at risk for respiratory complications, the median tidal volume was still 9.8 ml/kg (IQR 8.6-10.7) and PEEP was applied in 66% of patients with a median value of 5 cmH20 (IQR 4-5). On multivariate analyses positive predictors of tidal volume size included male sex (p < 0.01), height (p = 0.04) and weight (p < 0.001). Positive predictors of the use of PEEP included surgery in a tertiary hospital (OR = 3.11; 95% CI: 1.05 to 9.23) and expected prolonged duration of surgery (OR = 2.47; 95% CI: 1.04 to 5.84). In mechanically ventilated patients under general anaesthesia, tidal volume was high and PEEP was applied to the majority of patients, but at modest levels. The findings of our study suggest that the control groups of previous randomized controlled trials do not closely

  9. Positive end-expiratory pressure-induced changes in end-expiratory lung volume measured by spirometry and electric impedance tomography.

    PubMed

    Grivans, C; Lundin, S; Stenqvist, O; Lindgren, S

    2011-10-01

    A bedside tool for monitoring changes in end-expiratory lung volume (ΔEELV) would be helpful to set optimal positive end-expiratory pressure (PEEP) in acute lung injury/acute respiratory distress syndrome patients. The hypothesis of this study was that the cumulative difference of the inspiratory and expiratory tidal volumes of the first 10 breaths after a PEEP change accurately reflects the change in lung volume following a PEEP alteration. Changing PEEP induces lung volume changes, which are reflected in differences between inspiratory and expiratory tidal volumes measured by spirometry. By adding these differences with correction for offset, for the first 10 breaths after PEEP change, cumulative tidal volume difference was calculated to estimate ΔEELV(VT) ((i-e)) . This method was evaluated in a lung model and in patients with acute respiratory failure during a PEEP trial. In patients, ΔEELV(VT) ((i-e)) were compared with simultaneously measured changes in lung impedance, by electric impedance tomography (EIT), using calibration vs. tidal volume to estimate changes in ΔEELV(EIT) . In the lung model, there was close correlation (R(2)  = 0.99) between ΔEELV(VT) ((i-e)) and known lung model volume difference, with a bias of -4 ml and limits of agreement of 42 and -50 ml. In 12 patients, ΔEELV(EIT) was closely correlated to ΔEELV(VT) ((i-e)) (R(2)  = 0.92), with mean bias of 50 ml and limits of agreement of 131 and -31 ml. Changes in EELV estimated by EIT (ΔEELV(EIT) ) exceeded measurements by spirometry (ΔEELV(VT) ((i-e)) ), with 15 (±15)%. We conclude that spirometric measurements of inspiratory-expiratory tidal volumes agree well with impedance changes monitored by EIT and can be used bedside to estimate PEEP-induced changes in EELV. 2011 The Authors Acta Anaesthesiologica Scandinavica, 2011 The Acta Anaesthesiologica Scandinavica Foundation.

  10. Prevention of atelectasis formation during induction of general anesthesia.

    PubMed

    Rusca, Marco; Proietti, Stefania; Schnyder, Pierre; Frascarolo, Philippe; Hedenstierna, Göran; Spahn, Donat R; Magnusson, Lennart

    2003-12-01

    General anesthesia promotes atelectasis formation, which is augmented by administration of large oxygen concentrations. We studied the efficacy of positive end-expiratory pressure (PEEP) application during the induction of general anesthesia (fraction of inspired oxygen [FIO(2)] 1.0) to prevent atelectasis. Sixteen adult patients were randomly assigned to one of two groups. Both groups breathed 100% O(2) for 5 min and, after a general anesthesia induction, mechanical ventilation via a face mask with a FIO(2) of 1.0 for another 5 min before endotracheal intubation. Patients in the first group (PEEP group) had continuous positive airway pressure (CPAP) (6 cm H(2)O) and mechanical ventilation via a face mask with a PEEP of 6 cm H(2)O. No CPAP or PEEP was applied in the control group. Atelectasis, determined by computed radiograph tomography, and analysis of blood gases were measured twice: before the beginning of anesthesia and directly after the intubation. There was no difference between groups before the anesthesia induction. After endotracheal intubation, patients in the control group showed an increase of the mean area of atelectasis from 0.8% +/- 0.9% to 4.1% +/- 2.0% (P = 0.0002), whereas the patients of the PEEP group showed no change (0.5% +/- 0.6% versus 0.4% +/- 0.7%). After the intubation with a FIO(2) of 1.0, PaO(2) was significantly higher in the PEEP group than in the control (591 +/- 54 mm Hg versus 457 +/- 99 mm Hg; P = 0.005). Atelectasis formation is prevented by application of PEEP during the anesthesia induction despite the use of large oxygen concentrations, resulting in improved oxygenation. Application of positive end-expiratory pressure during the induction of general anesthesia prevents atelectasis formation. Furthermore, it improves oxygenation and probably increases the margin of safety before intubation. Therefore, this technique should be considered for all anesthesia induction, at least in patients at risk of difficult airway management

  11. Do We Deliver the Pressures We Intend to When Using a T-Piece Resuscitator?

    PubMed Central

    Walther, Frans J.; Roehr, Charles C.; te Pas, Arjan B.

    2013-01-01

    Background A T-piece resuscitator (TPR) uses a built-in manometer to set the inflation pressures, but we are not informed what pressures are actually delivered distally. Aim of this study was to measure the proximal and distal pressures under different gas conditions when using a TPR. Methodology/Findings A test lung was ventilated using a TPR (PIP 25 cmH2O, PEEP 5 cmH2O) with a gas flow rate of 8 L/min. A) Pressure delivered by six different TPRs was tested. To test variability 20 participants were asked to set PEEP and PIP pressures to 25/5 cmH2O. B) PIP and PEEP were measured proximal and distal of the TPR when using standard tubing or heated tubing with or without a humidifier. In experiment A mean (SD) proximal PIP and PEEP of the TPRs were respectively 20.3 (0.3) cmH2O (19.9–20.6 cmH2O) and 4.9 (0.1) cmH2O. When 20 participants set pressures; PIP 26.7 (0.5) cm H2O and PEEP 5.9 (0.44) cmH2O were measured. Experiment B showed that the decrease of PIP between proximal and distal pressures was not clinically significant. However there was a significant decrease of PEEP using the standard tubing (5.1 (0.1) cmH2O proximally versus 4.8 (0.2) cmH2O distally; p<0.001) compared to, when using a humidifier with associated tubing and the humidifier turned on, 5.1 (0.1) proximally versus 3.9 (0.2) cmH2O distally; (p<0.001). Conclusion/Significance The accuracy of the built-in manometer of a TPR is acceptable. Most pressures set proximally are comparable to the actual pressures delivered distally. However, when using tubing associated with the humidifier PEEP decreases distally by 1.1–1.2 cmH2O and users should anticipate on this. PMID:23717652

  12. Effect of Different Respiratory Modes on Return of Spontaneous Circulation in a Newborn Piglet Model of Hypoxic Cardiac Arrest.

    PubMed

    Mendler, Marc R; Weber, Claudia; Hassan, Mohammad A; Huang, Li; Waitz, Markus; Mayer, Benjamin; Hummler, Helmut D

    2016-01-01

    There are no clear evidence-based recommendations on the use of different techniques of respiratory support and chest compressions (CC) during neonatal cardiopulmonary resuscitation (CPR). To determine the effects of different respiratory support strategies along with CC representing clinical practice on the return of spontaneous circulation (ROSC) in hypoxic newborn piglets with cardiac arrest. We hypothesized that use of a T-piece resuscitator (TPR) providing positive end-expiratory pressure (PEEP) reduces time to ROSC as compared to a self-inflating bag (SIB) without PEEP. Furthermore, we explored the effects of a ventilator providing inflations without synchrony to CC. Thirty-three newborn piglets were exposed to hypoxia until asystole occurred and randomized into three groups and resuscitated according to ILCOR guidelines: group 1 = TPR [peak inspiratory pressure (PIP)/PEEP of 25/5 cm H2O, rate 30/min], inflations interposed between CC (3:1 ratio); group 2 = SIB (PIP of 25 cm H2O without PEEP, rate 30/min), inflations interposed between CC (3:1 ratio), and group 3 = ventilator (PIP/PEEP of 25/5 cm H2O, rate 30/min), CC were applied with a rate of 120/min without synchrony to inflations. Animals were supported for 120 min after ROSC. Primary outcome was time to ROSC. All animals achieved ROSC. We found no significant difference in time to ROSC between groups [median (IQR); TPR: 150 s (150-210); SIB: 150 s (120-180); ventilator: 180 s (150-345)]. There was no difference in use of epinephrine, in blood gases or hemodynamic parameters during the 120-min observation time after ROSC. We found no significant effect of different respiratory support strategies during CPR on ROSC. © 2015 S. Karger AG, Basel.

  13. Neopuff T-piece resuscitator: does device design affect delivered ventilation?

    PubMed

    Hinder, Murray; Jani, Pranav; Priyadarshi, Archana; McEwan, Alistair; Tracy, Mark

    2017-05-01

    The T-piece resuscitator (TPR) is in common use worldwide to deliver positive pressure ventilation during resuscitation of infants <10 kg. Ease of use, ability to provide positive end-expiratory pressure (PEEP), availability of devices inbuilt into resuscitaires and cheaper disposable options have increased its popularity as a first-line device for term infant resuscitation. Research into its ventilation performance is limited to preterm infant and animal studies. Efficacy of providing PEEP and the use of TPR during term infant resuscitation are not established. The aim of this study is to determine if delivered ventilation with the Neopuff brand TPR varied with differing (preterm to term) test lung compliances (Crs) and set peak inspiratory pressures (PIP). A single operator experienced in newborn resuscitation provided positive pressure ventilation in a randomised sequence to three different Crs models (0.5, 1 and 3 mL/cmH2O) at three different set PIP (20, 30 and 40 cmH2O). Set PEEP (5 cmH2O), gas flow rate and inflation rate were the same for each sequence. A total of 1087 inflations were analysed. The delivered mean PEEP was Crs dependent across set PIP range, rising from 4.9 to 8.2 cmH2O. At set PIP 40 cmH2O and Crs 3 mL/cmH2O, the delivered mean PIP was significantly lower at 35.3 cmH2O. As Crs increases, the Neopuff TPR can produce clinically significant levels of auto-PEEP and thus may not be optimal for the resuscitation of term infants with healthy lungs. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  14. Assessment of Ventilation Distribution during Laparoscopic Bariatric Surgery: An Electrical Impedance Tomography Study.

    PubMed

    Stankiewicz-Rudnicki, Michal; Gaszynski, Wojciech; Gaszynski, Tomasz

    2016-01-01

    Introduction. The aim of the study was to assess changes of regional ventilation distribution at the level of the 3rd intercostal space in the lungs of morbidly obese patients as a result of general anaesthesia and laparoscopic surgery as well as the relation of these changes to lung mechanics. We also wanted to determine if positive end-expiratory pressure of 10 cm H2O prevents the expected atelectasis in the morbidly obese patients during general anaesthesia. Materials and Methods. 49 patients completed the examination and were randomized to 2 groups: ventilated without positive end-expiratory pressure (PEEP 0) and with PEEP of 10 cm H2O (PEEP 10) preceded by a recruitment maneuver with peak inspiratory pressure of 40 cm H2O. Impedance Ratio (IR) was utilized to examine ventilation distribution changes as a result of anaesthesia, pneumoperitoneum, and change of body position. We also analyzed intraoperative respiratory mechanics and pulse oximetry values. Results. In both groups general anaesthesia caused a ventilation shift towards the nondependent lungs which was not further intensified after pneumoperitoneum. Reverse Trendelenburg position promoted homogeneous ventilation distribution. Respiratory system compliance was reduced after insufflation and improved after exsufflation of pneumoperitoneum. There were no statistically significant differences in ventilation distribution between the examined groups. Respiratory system compliance, plateau pressure, and pulse oximetry values were higher in PEEP 10. Conclusions. Changes of ventilation distribution in the obese do occur at cranial lung regions. During pneumoperitoneum alterations of ventilation distribution may not follow the direction of the changes of lung mechanics. In the obese patients PEEP level of 10 cm H2O preceded by a recruitment maneuver improves respiratory compliance and oxygenation but does not eliminate atelectasis induced by general anaesthesia.

  15. Effects of positive end-expiratory pressure on regional distribution of tidal volume and recruitment in adult respiratory distress syndrome.

    PubMed

    Gattinoni, L; Pelosi, P; Crotti, S; Valenza, F

    1995-06-01

    The distribution of tidal volume (VT) and recruitment was investigated by chest computed tomography (CT) in eight sedated-paralyzed patients with the adult respiratory distress syndrome (ARDS). A CT section was obtained in the supine position at 0, 5, 10, 15, and 20 cm H2O positive end-expiratory pressure (PEEP) and at the corresponding inspiratory plateau pressure (21 +/- 1.8, 26 +/- 1.4, 31 +/- 1.8, 38 +/- 2.1, and 46 +/- 3.2 cm H2O [mean +/- SE]), keeping VT constant. Each CT section was divided along its ventral-dorsal height into 10 equally spaced intervals (levels). Vi(insp) and Vi(exp) were defined as the gas volume for level i (i = 1 to 10) at end-inspiration and at end-expiration, respectively. The following variables were computed at each lung level: (1) distribution of CT section tidal volume (VTct), i.e., the fraction of VT that inflates a given lung level; (2) the plateau-induced and PEEP-induced recruitment, i.e., the amount of lung tissue previously collapsed that inflates at plateau pressure and at PEEP, respectively; (3) the reopening-collapsing tissue, i.e., the amount of lung tissue that regains inflation at plateau pressure and collapses at PEEP. With increasing PEEP from 0 to 20 cm H2O, the VTct distribution decreased significantly (p < 0.01) in the upper levels, did not change in the middle levels, and increased significantly (p < 0.01) in the lower levels.(ABSTRACT TRUNCATED AT 250 WORDS)

  16. Positive end-expiratory pressure prevents atelectasis during general anaesthesia even in the presence of a high inspired oxygen concentration.

    PubMed

    Neumann, P; Rothen, H U; Berglund, J E; Valtysson, J; Magnusson, A; Hedenstierna, G

    1999-03-01

    General anaesthesia impairs the gas exchange in the lungs, and moderate desaturation (SaO2 86-90%) occurred in 50% of anaesthetised patients in a blinded pulse oximetry study. A high FiO2 might reduce the risk of hypoxaemia, but can also promote atelectasis. We hypothesised that a moderate positive end-expiratory pressure (PEEP) level of 10 cmH2O can prevent atelectasis during ventilation with an FiO2 = 1.0. Atelectasis was evaluated by computed tomography (CT) in 13 ASA I-II patients undergoing elective surgery. CT scans were obtained before and 15 min after induction of anaesthesia. Then, recruitment of collapsed lung tissue was performed as a "vital capacity manoeuvre" (VCM, inspiration with Paw = 40 cmH2O for 15 s), and a CT scan was obtained at the end of the VCM. Thereafter, PEEP = 0 cmH2O was applied in group 1, and PEEP = 10 cmH2O in group 2. Additional CT scans were obtained after the VCM. Oxygenation was measured before and after the VCM. Atelectasis (> 1 cm2) was present in 12 of the 13 patients after induction of anaesthesia. At 5 and 10 min after the VCM, atelectasis was significantly smaller in group 2 than group 1 (P < 0.005). A significant inverse correlation was found between PaO2 and atelectasis. PEEP = 10 cmH2O reduced atelectasis formation after a VCM, when FiO2 = 1.0 was used. Thus, a VCM followed by PEEP = 10 cmH2O should be considered when patients are ventilated with a high FiO2 and gas exchange is impaired.

  17. Effects of reduction of inspired oxygen fraction or application of positive end-expiratory pressure after an alveolar recruitment maneuver on respiratory mechanics, gas exchange, and lung aeration in dogs during anesthesia and neuromuscular blockade.

    PubMed

    De Monte, Valentina; Grasso, Salvatore; De Marzo, Carmelinda; Crovace, Antonio; Staffieri, Francesco

    2013-01-01

    To evaluate the effectiveness of reduction of inspired oxygen fraction (Fio(2)) or application of positive end-expiratory pressure (PEEP) after an alveolar recruitment maneuver (ARM) in minimizing anesthesia-induced atelectasis in dogs. 30 healthy female dogs. During anesthesia and neuromuscular blockade, dogs were mechanically ventilated under baseline conditions (tidal volume, 12 mL/kg; inspiratory-to-expiratory ratio, 1:2; Fio(2), 1; and zero end-expiratory pressure [ZEEP]). After 40 minutes, lungs were inflated (airway pressure, 40 cm H(2)O) for 20 seconds. Dogs were then exposed to baseline conditions (ZEEP100 group), baseline conditions with Fio(2) reduced to 0.4 (ZEEP40 group), or baseline conditions with PEEP at 5 cm H(2)O (PEEP100 group; 10 dogs/group). For each dog, arterial blood gas variables and respiratory system mechanics were evaluated and CT scans of the thorax were obtained before and at 5 (T5) and 30 (T30) minutes after the ARM. Compared with pre-ARM findings, atelectasis decreased and Pao(2):Fio(2) ratio increased at T5 in all groups. At T30, atelectasis and oxygenation returned to pre-ARM findings in the ZEEP100 group but remained similar to T5 findings in the other groups. At T5 and T30, lung static compliance in the PEEP100 group was higher than values in the other groups. Application of airway pressure of 40 cm H(2)O for 20 seconds followed by Fio(2) reduction to 0.4 or ventilation with PEEP (5 cm H(2)O) was effective in diminishing anesthesia-induced atelectasis and maintaining lung function in dogs, compared with the effects of mechanical ventilation providing an Fio(2) of 1.

  18. [Effect of changes in airway pressure and the inspiratory volume on the fluid filtration rate and pulmonary artery pressure in isolated rabbit lungs perfused with blood and acellular solution].

    PubMed

    Crespo, Astrid; Novoa, Eva; Urich, Daniela; Trejo, Humberto; Pezzulo, Alejandro; Sznajder, Jacob I; Livia, Fernández; Sánchez-de León, Roberto

    2006-12-01

    It has been reported that ventilation with large tidal volumes causes pulmonary edema in rats by the stimulation and release of proinflammatory mediators. Our objective was to determine the level at which volutrauma induced by changes in Airway Pressure (PAW) and Inspiratory Volume (VI) produce significant changes on the Fluid Filtration Rate (FFR) and Pulmonary Artery Pressure (PAP) in lungs perfused with blood (cellular groups) or with a buffer-albumin solution (acellular groups), with a Positive End Expiratory Pressure (PEEP) 0 or 2 cmH2O and to study the effect of a vasodilator with antiinflammatory properties (fenoterol) in blood-perfused groups. Three experimental groups were used: the cellular groups studied the effect of increased PAW and IV in isolated lungs perfused with blood and PEEP 0 and 2; the acellular groups studied the increased PAW and IV in isolated lungs perfused with a buffer-albumin solution and PEEP 0 and 2; The fenoterol group studied the effect of increased PAW and IV in isolated lungs perfused with blood + fenoterol and PEEP 2. The results show that an increase of FFR is produced earlier in acellular groups than in cellular ones and that the damage in cellular groups is microscopically and macroscopically inferior when compared to acellular groups. Fenoterol did not inhibit edema formation, and that PEEP 2, both in the cellular and the acellular groups, has a protective effect. We propose the possible existence of mediators with protective effects against the formation of pulmonary edema in the blood. These data suggest that volutrauma induced pulmonary edema has a predominantly traumatic origin when the lungs are perfused with blood.

  19. Assessment of Ventilation Distribution during Laparoscopic Bariatric Surgery: An Electrical Impedance Tomography Study

    PubMed Central

    Gaszynski, Wojciech

    2016-01-01

    Introduction. The aim of the study was to assess changes of regional ventilation distribution at the level of the 3rd intercostal space in the lungs of morbidly obese patients as a result of general anaesthesia and laparoscopic surgery as well as the relation of these changes to lung mechanics. We also wanted to determine if positive end-expiratory pressure of 10 cm H2O prevents the expected atelectasis in the morbidly obese patients during general anaesthesia. Materials and Methods. 49 patients completed the examination and were randomized to 2 groups: ventilated without positive end-expiratory pressure (PEEP 0) and with PEEP of 10 cm H2O (PEEP 10) preceded by a recruitment maneuver with peak inspiratory pressure of 40 cm H2O. Impedance Ratio (IR) was utilized to examine ventilation distribution changes as a result of anaesthesia, pneumoperitoneum, and change of body position. We also analyzed intraoperative respiratory mechanics and pulse oximetry values. Results. In both groups general anaesthesia caused a ventilation shift towards the nondependent lungs which was not further intensified after pneumoperitoneum. Reverse Trendelenburg position promoted homogeneous ventilation distribution. Respiratory system compliance was reduced after insufflation and improved after exsufflation of pneumoperitoneum. There were no statistically significant differences in ventilation distribution between the examined groups. Respiratory system compliance, plateau pressure, and pulse oximetry values were higher in PEEP 10. Conclusions. Changes of ventilation distribution in the obese do occur at cranial lung regions. During pneumoperitoneum alterations of ventilation distribution may not follow the direction of the changes of lung mechanics. In the obese patients PEEP level of 10 cm H2O preceded by a recruitment maneuver improves respiratory compliance and oxygenation but does not eliminate atelectasis induced by general anaesthesia. PMID:28058262

  20. 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

  1. Optimizing positive end-expiratory pressure by oscillatory mechanics minimizes tidal recruitment and distension: an experimental study in a lavage model of lung injury

    PubMed Central

    2012-01-01

    Introduction It is well established that during mechanical ventilation of patients with acute respiratory distress syndrome cyclic recruitment/derecruitment and overdistension are potentially injurious for lung tissues. We evaluated whether the forced oscillation technique (FOT) could be used to guide the ventilator settings in order to minimize cyclic lung recruitment/derecruitment and cyclic mechanical stress in an experimental model of acute lung injury. Methods We studied six pigs in which lung injury was induced by bronchoalveolar lavage. The animals were ventilated with a tidal volume of 6 ml/kg. Forced oscillations at 5 Hz were superimposed on the ventilation waveform. Pressure and flow were measured at the tip and at the inlet of the endotracheal tube respectively. Respiratory system reactance (Xrs) was computed from the pressure and flow signals and expressed in terms of oscillatory elastance (EX5). Positive end-expiratory pressure (PEEP) was increased from 0 to 24 cm H2O in steps of 4 cm H2O and subsequently decreased from 24 to 0 in steps of 2 cm H2O. At each PEEP step CT scans and EX5 were assessed at end-expiration and end-inspiration. Results During deflation the relationship between both end-expiratory and end-inspiratory EX5 and PEEP was a U-shaped curve with minimum values at PEEP = 13.4 ± 1.0 cm H2O (mean ± SD) and 13.0 ± 1.0 cm H2O respectively. EX5 was always higher at end-inspiration than at end-expiration, the difference between the average curves being minimal at 12 cm H2O. At this PEEP level, CT did not show any substantial sign of intra-tidal recruitment/derecruitment or expiratory lung collapse. Conclusions Using FOT it was possible to measure EX5 both at end-expiration and at end-inspiration. The optimal PEEP strategy based on end-expiratory EX5 minimized intra-tidal recruitment/derecruitment as assessed by CT, and the concurrent attenuation of intra-tidal variations of EX5 suggests that it may also minimize tidal mechanical stress

  2. Continuous Non-Invasive Monitoring of Tidal Volumes by Measurement of Tidal Impedance in Neonatal Piglets

    PubMed Central

    Kurth, Florian; Zinnow, Fabienne; Prakapenia, Alexandra; Dietl, Sabrina; Winkler, Stefan; Ifflaender, Sascha; Rüdiger, Mario; Burkhardt, Wolfram

    2011-01-01

    Background Electrical Impedance measurements can be used to estimate the content of intra-thoracic air and thereby give information on pulmonary ventilation. Conventional Impedance measurements mainly indicate relative changes, but no information concerning air-volume is given. The study was performed to test whether a 3-point-calibration with known tidal volumes (VT) during conventional mechanical ventilation (CMV) allows subsequent calculation of VT from total Tidal-Impedance (tTI) measurements using Quadrant Impedance Measurement (QIM). In addition the distribution of TI in different regions of the thorax was examined. Methodology and Principal Findings QIM was performed in five neonatal piglets during volume-controlled CMV. tTI values at three different VT (4, 6, 8 ml/kg) were used to establish individual calibration curves. Subsequently, each animal was ventilated with different patterns of varying VT (2–10 ml/kg) at different PEEP levels (0, 3, 6, 9, 12 cmH2O). VT variation was repeated after surfactant depletion by bronchoalveolar lavage. VT was calculated from tTI values (VTcalc) and compared to the VT delivered by the ventilator (VTPNT). Bland-Altman analysis revealed good agreement between VTcalc and VTPNT before (bias −0.08 ml; limits of agreement −1.18 to 1.02 ml at PEEP = 3 cmH2O) and after surfactant depletion (bias −0.17 ml; limits of agreement −1.57 to 1.22 ml at PEEP = 3 cmH2O). At higher PEEP levels VTcalc was lower than VTPNT, when only one fixed calibration curve (at PEEP 3 cmH2O) was used. With a new calibration curve at each PEEP level the method showed similar accuracy at each PEEP level. TI showed a homogeneous distribution over the four assessed quadrants with a shift toward caudal regions of the thorax with increasing VT. Conclusion Tidal Impedance values could be used for precise and accurate calculation of VT during CMV in this animal study, when calibrated at each PEEP level. PMID:21687746

  3. 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

  4. Effects of lung surfactant factor (LSF) treatment on gas exchange and histopathological changes in an animal model of adult respiratory distress syndrome (ARDS): comparison of recombinant LSF with bovine LSF.

    PubMed

    Häfner, D; Germann, P G; Hauschke, D

    1994-10-01

    Repetitive lung lavage of adult rats leads to lung injury similar to ARDS resulting in poor gas exchange, protein leakage and infiltration of polymorphonuclear neutrophils (PMN) into the alveolar spaces (J Appl Physiol 1983; 55: 131-138). In a previous dose response comparison we have demonstrated that poor gas exchange could be improved by lung surfactant factor (LSF) instillation soon after lavage. Since Surfacten (Tokyo Tanabe Co. Ltd., Tokyo, Japan) was described in vitro to inhibit PMN activity, we compared this preparation with a Recombinant LSF preparation (Byk Gulden, Konstanz, Germany; phospholipids plus human identical surfactant protein C) at doses of 25, 50 and 100 mg/kg body weight. Their efficacy was compared with an untreated control group with respect to improving gas exchange, inhibition of hyaline membrane formation and inhibition of the inflammatory response after multiple lavage. Tracheotomized rats were pressure-controlled ventilated (Siemens Servo Ventilator 900C, Sweden) with 100% oxygen at a respiratory rate of 30 breaths/min, inspiration:expiration ratio of 1:2, peak inspiratory pressure (PIP) of 28 cmH2O at positive end-expiratory pressure (PEEP) of 8 cmH2O. Two hours after LSF administration PEEP was reduced from 8 to 6 cmH2O (first PEEP-reduction), from 6 to 3 (second reduction) and from 3 to 0 cmH2O (third reduction) and finally raised to 8 cmH2O. Results for the averaged partial arterial oxygen pressure [PaO2 (mmHg)] of the 2 h period [PaO2(5'-120')] and for the PaO2 during the second PEEP reduction [PaO2(PEEP23/3] were calculated. Both LSF preparations caused a dose-dependent increase of the PaO2 (5'-120') and the PaO2(PEEP23/3). Similarly, the formation of hyaline membranes was inhibited by both LSF preparations in a dose-dependent manner. Inhibition of the inflammatory response (infiltration of PMN) was not effected by either of the LSF preparations at any dose level. The described variations in ventilator settings are useful to

  5. Lung recruitment manoeuvres do not cause haemodynamic instability or oxidative stress but improve oxygenation and lung mechanics in a newborn animal model: an observational study.

    PubMed

    de la Osa, Agustín Mendiola; Garcia-Fernandez, Javier; Llorente-Cantarero, Francisco J; Gil-Campos, Mercedes; Muñoz-Villanueva, María C; De la Torre Aguilar, María J; de la Rosa, Ignacio Ibarra; Pérez-Navero, Juan L

    2014-09-01

    Lung recruitment manoeuvres in neonates during anaesthesia are not performed routinely due to concerns about causing barotrauma, haemodynamic instability and oxidative stress. To assess the influence of recruitment manoeuvres and positive end-expiratory pressure (PEEP) on haemodynamics, oxidative stress, oxygenation and lung mechanics. A prospective experimental study. Experimental Unit, La Paz University Hospital, Madrid, Spain. Eight newborn piglets (<48 h) with healthy lungs under general anaesthesia. The recruitment manoeuvres in pressure-controlled ventilation (PCV) were performed along with a constant driving pressure of 15 cmH2O. After the recruitment manoeuvres, PEEP was reduced in a stepwise fashion to find the maximal dynamic compliance step (maxCDyn-PEEP). Blood oxidative stress biomarkers (lipid peroxidation products, protein carbonyls, total glutathione, oxidised glutathione, reduced glutathione and activity of glutathione peroxidase) were analysed. Haemodynamic parameters, arterial partial pressure of oxygen (paO2), tidal volume (Vt), dynamic compliance (Cdyn) and oxidative stress biomarkers were measured. The recruitment manoeuvres did not induce barotrauma. Haemodynamic instability was not detected either in the maximum pressure step (overdistension step 5) or during the entire process. No substantial differences were observed in blood oxidative stress parameters analysed as compared with their baseline values (with 0 PEEP) or the values obtained 180 min after the onset of the recruitment manoeuvres (optimal PEEP). Significant maximal values were achieved in step 14 with an increase in paO2 (32.43 ± 8.48 vs. 40.39 ± 15.66 kPa; P = 0.037), Vt (47.75 ± 13.59 vs. 73.87 ± 13.56 ml; P = 0.006) and Cdyn (2.50 ± 0.64 vs. 4.75 ± 0.88 ml cmH2O; P < 0.001). Maximal dynamic compliance step (maxCdyn-PEEP) was 2 cmH2O. Recruitment manoeuvres in PCV with a constant driving pressure are a well tolerated open

  6. 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.

  7. Near-fatal misuse of medical tape around an endotracheal tube connector during inhalation anesthesia in a horse.

    PubMed

    Gregson, Rachael; Clutton, R Eddie

    2012-09-01

    A 7-year-old gelded Irish sports horse weighing 650 kg was anesthetized on 2 consecutive days for lavage of a septic right radio-carpal joint. On both occasions the endotracheal tube connector, which had been bound in medical tape to produce an airtight seal, functioned as a unidirectional valve during mechanical ventilation, retarding expiration, imposing positive end expiratory pressure (PEEP), and probably continuous positive airway pressure (CPAP). The equipment dysfunction was not identified on either occasion despite close inspection prompted by progressive increases in airway pressure and thoracic distension. Whilst the PEEP and CPAP exerted unexpectedly modest cardiovascular effects and the horse recovered uneventfully on both occasions, the improvisation may have proven fatal in a higher-risk subject.

  8. Vocalization-correlated respiratory movements in the squirrel monkey.

    PubMed

    Häusler, U

    2000-10-01

    Respiratory abdominal movements associated with vocalization were recorded in awake squirrel monkeys. Several call types, such as peeping, trilling, cackling, and err-chucks, were accompanied by large vocalization-correlated respiratory movements (VCRM) that started before vocalization. During purring, in contrast, only small VCRM were recorded that started later after vocal onset. VCRM during trill calls, a vocalization type with repetitive frequency modulation, showed a modulation in the rhythm of the frequency changes. A correlation with amplitude modulation was also present, but more variable. As high frequencies need a higher lung pressure for production than low frequencies, the modulation of VCRM seems to serve to optimize the lung pressure in relation to the vocalization frequency. The modulation, furthermore, may act as a mechanism to produce different trill variants. During err-chucks and staccato peeps, which show a large amplitude modulation, a nonmodulated VCRM occurred. This indicates the existence of a laryngeal amplitude-controlling mechanism that is independent from respiration.

  9. A closed-loop system for control of the fraction of inspired oxygen and the positive end-expiratory pressure in mechanical ventilation.

    PubMed

    Tehrani, Fleur T

    2012-11-01

    A system for automatic control of the fraction of inspired oxygen (F(IO2)), and positive end-expiratory pressure (PEEP) for patients on mechanical ventilation is presented. In this system, F(IO2) is controlled by using two interacting mechanisms; a fine control mechanism and a fast stepwise procedure used when patient's oxygen saturation level (S(pO2)) falls abruptly. The PEEP level is controlled automatically and in relation to F(IO2) to prevent hypoxemia. The system has been tested by using bench studies and computer simulations. The results show the potential of the system as an aide in effective oxygenation of patients on mechanical ventilation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Common-path Fourier domain optical coherence tomography of irradiated human skin and ventilated isolated rabbit lungs

    NASA Astrophysics Data System (ADS)

    Popp, A.; Wendel, M.; Knels, L.; Knuschke, P.; Mehner, M.; Koch, T.; Boller, D.; Koch, P.; Koch, E.

    2005-08-01

    A compact common path Fourier domain optical coherence tomography (FD-OCT) system based on a broadband superluminescence diode is used for biomedical imaging. The epidermal thickening of human skin after exposure to ultraviolet radiation is measured to proof the feasibility of FD-OCT for future substitution of invasive biopsies in a long term study on natural UV skin protection. The FD-OCT system is also used for imaging lung parenchyma. FD-OCT images of a formalin fixated lung show the same alveolar structure as scanning electron microscopy images. In the ventilated and blood-free perfused isolated rabbit lung FD-OCT is used for real-time cross-sectional image capture of alveolar mechanics throughout tidal ventilation. The alveolar mechanics changing from alternating recruitment-derecruitment at zero positive end-expiratory pressure (PEEP) to persistent recruitment after applying a PEEP of 5 cm H2O is observed in the OCT images.

  11. Shorebird use of managed wetlands in the Mississippi Alluvial Valley

    USGS Publications Warehouse

    Twedt, Daniel J.; Nelms, Curtis O.; Rettig, Virginia E.; Aycock, S. Ray

    1998-01-01

    We assessed shorebird densities on managed wetland habitats during fall and winter within the primarily agricultural landscape of the Mississippi Alluvial Valley. From November through March, shorebird densities were greater on soybean fields than on rice or moist-soil fields. Killdeer (Charadrius vociferus) and Common Snipe (Gallinago gallinago) were common throughout winter, whereas Yellowlegs (Tringa spp.) and ?peep? sandpipers (Calidris spp.) were present but less abundant. During fall, Dowitchers (Limnodromus spp.), Pectoral Sandpipers (Calidris melanotos), Killdeer, and peep sandpipers were the most abundant species on managed shorebird habitat units. Although shorebird densities were consistently greater on habitats managed by drawing down existing water, we were unable to detect a significant difference in densities from areas managed by flooding previously dry habitat.

  12. ProSeal laryngeal mask airway in infants and toddlers with upper respiratory tract infections: a randomized control trial of spontaneous vs pressure control ventilation.

    PubMed

    Sinha, Aparna; Sharma, Bimla; Sood, Jayashree

    2009-10-01

    ProSeal LMA (PLMA), one of the advanced supraglottic devices has been successfully used to provide both spontaneous and controlled ventilation in children with upper respiratory tract infection (URTI). URTI does not imply restriction of disease to upper respiratory tract; it has been shown to produce pulmonary dysfunction. PEEP has been shown to improve oxygenation in such cases. This randomized prospective study was designed to compare postoperative adverse events associated with spontaneous respiration (SR) and pressure control ventilation (PCV) with PEEP in infants and toddlers with URTI when using PLMA as an airway device. In the present study, 90 children, 6 months-2 years, scheduled for infra umbilical surgery were randomized to receive either SR or PCV with PEEP of 5cm H2O. Patients with risk of aspiration, bronchial asthma, anticipated difficult airway, snoring, passive smoking, morbid obesity, coexisting pulmonary and cardiac disease, lower respiratory tract infection, fever > 38 degrees C and sneezing, were excluded. At emergence, airway secretions, coughing, breath holding, bronchospasm, upper airway obstruction or laryngospasm (LS) were assessed. The adverse events were significantly higher in spontaneously breathing patients. Score of adverse events was 6.33 +/- 1.6 in PCV and 7.7 +/- 2.2 in SR group (P = 0.001). The mean SpO2 (%) in PACU was 96.5 +/- 2 in PCV and 94.4 +/- 1.37 in SR (P = 000). Pressure control ventilation with PEEP using PLMA is associated with lower incidence of adverse events in comparison to spontaneous respiration in infants and toddlers with upper respiratory tract infection undergoing infra umbilical surgeries under general anesthesia.

  13. The Use of ATP-MgCl2 in the Treatment of Injury and Shock.

    DTIC Science & Technology

    1986-03-11

    thermal injury alters local adenine nucleotide levels and is associated with elevated glucose utilization and blood flow in muscles of the burned region...Turinzky, J., Chaudry, I.H., Loegering, D.J. and Nelson, R.M. "Energy metabolism and blood flow in burned limb muscle." Physiologist 22:126, 1979...hours. We examined the cardiopulmonary response to PEEP in dogs before and after the intratrachael inoculation of Psuedomonas aeruginosa (l x lO9

  14. Measurement of respiratory mechanics using the Puritan-Bennett 7200a ventilator.

    PubMed

    Chartrand, D; Dionne, B; Jodoin, C; Lorange, M; Lapointe, A

    1993-11-01

    This study was designed in order to validate the respiratory mechanical variables measured by the Puritan-Bennett 7200a ventilator equipped with the 30/40 module. Two ventilators were connected to a lung model and submitted to several breathing patterns by modifying the respiratory rate, the tidal volume, the inspiratory flow-rate and the model resistance. The inspiratory flow-rate (V), tidal volume (VT), peak inspiratory pressure (Pmax), plateau pressure (Pplat) and PEEP measured by the ventilators were compared with the same variables measured at the connection between the breathing circuit and the lung model. The compliance (C30/40) and the resistance (R30/40) calculated by the 30/40 module were compared with those calculated by using the variables measured by the reference equipment. Both ventilators made a constant underestimation of V by 2.8 and 3.7 L.min-1, respectively. The VT was measured with a mean error of less than 10 ml but did not reflect the preselected values in the presence of an intrinsic PEEP. The Pplat was overestimated by 7 and 10%, respectively. The same calibration error was observed with Pmax which was also affected by a pressure gradient due to the resistance of the breathing circuit. Even in the absence of intrinsic PEEP, C30/40 presented an error due to the combination of the measurement errors on VT, Pplat and PEEP. Finally, R30/40 presented a high percentage of error due to the combination of the measurement errors on V, Pmax, and Pplat, and to a sporadic aberrant selection of V. Due to these numerous sources of error, the two ventilators studied did not give reliable estimates of resistance and compliance.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Ventilator-related causes of lung injury: the mechanical power.

    PubMed

    Gattinoni, L; Tonetti, T; Cressoni, M; Cadringher, P; Herrmann, P; Moerer, O; Protti, A; Gotti, M; Chiurazzi, C; Carlesso, E; Chiumello, D; Quintel, M

    2016-10-01

    We hypothesized that the ventilator-related causes of lung injury may be unified in a single variable: the mechanical power. We assessed whether the mechanical power measured by the pressure-volume loops can be computed from its components: tidal volume (TV)/driving pressure (∆P aw), flow, positive end-expiratory pressure (PEEP), and respiratory rate (RR). If so, the relative contributions of each variable to the mechanical power can be estimated. We computed the mechanical power by multiplying each component of the equation of motion by the variation of volume and RR: [Formula: see text]where ∆V is the tidal volume, ELrs is the elastance of the respiratory system, I:E is the inspiratory-to-expiratory time ratio, and R aw is the airway resistance. In 30 patients with normal lungs and in 50 ARDS patients, mechanical power was computed via the power equation and measured from the dynamic pressure-volume curve at 5 and 15 cmH2O PEEP and 6, 8, 10, and 12 ml/kg TV. We then computed the effects of the individual component variables on the mechanical power. Computed and measured mechanical powers were similar at 5 and 15 cmH2O PEEP both in normal subjects and in ARDS patients (slopes = 0.96, 1.06, 1.01, 1.12 respectively, R (2) > 0.96 and p < 0.0001 for all). The mechanical power increases exponentially with TV, ∆P aw, and flow (exponent = 2) as well as with RR (exponent = 1.4) and linearly with PEEP. The mechanical power equation may help estimate the contribution of the different ventilator-related causes of lung injury and of their variations. The equation can be easily implemented in every ventilator's software.

  16. 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.

  17. 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

  18. Nitric Oxide Synthase Promotes Distension-Induced Tracheal Venular Leukocyte Adherence

    PubMed Central

    Moldobaeva, Aigul; Rentsendorj, Otgonchimeg; Jenkins, John; Wagner, Elizabeth M.

    2014-01-01

    The process of leukocyte recruitment to the airways in real time has not been extensively studied, yet airway inflammation persists as a major contributor to lung pathology. We showed previously in vivo, that neutrophils are recruited acutely to the large airways after periods of airway distension imposed by the application of positive end-expiratory pressure (PEEP). Given extensive literature implicating products of nitric oxide synthase (NOS) in lung injury after ventilatory over-distension, we questioned whether similar mechanisms exist in airway post-capillary venules. Yet, endothelial nitric oxide has been shown to be largely anti-inflammatory in other systemic venules. Using intravital microscopy to visualize post-capillary tracheal venules in anesthetized, ventilated mice, the number of adherent leukocytes was significantly decreased in eNOS-/- mice under baseline conditions (2±1 cell/60 min observation) vs wild type (WT) C57BL/6 mice (7±2 cells). After exposure to PEEP (8 cmH2O for 1 min; 5 times), adherent cells increased significantly (29±5 cells) in WT mice while eNOS-/- mice demonstrated a significantly decreased number of adherent cells (11±4 cells) after PEEP. A similar response was seen when thrombin was used as the pro-inflammatory stimulus. In addition, mouse tracheal venular endothelial cells studied in vitro after exposure to cyclic stretch (18% elongation) or thrombin both demonstrated increased p-selectin expression that was significantly attenuated by NG-nitro-L-arginine methyl ester, N-acetylcysteine amide (NACA) and excess BH4. In vivo treatment with the ROS inhibitor NACA or co-factor BH4 abolished completely the PEEP-induced leukocyte adherence. These results suggest that pro-inflammatory stimuli cause leukocyte recruitment to tracheal endothelium in part due to eNOS uncoupling. PMID:25181540

  19. 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

  20. Pulsed Dose Delivery of Oxygen in Mechanically Ventilated Pigs with Acute Lung Injury

    DTIC Science & Technology

    2013-03-01

    atropine (0.54 mg/kg). They were then intubated with 7.5 French endotracheal tubes. A surgical plane of anesthesia was maintained with isoflurane...patients often require intubation and mechanical ventilation with supplemental oxygen and positive end-expiratory pressure (PEEP). To date, the...circuit, directly at the endotracheal tube. We used the SeQual Eclipse II, which was selected for its oxygen generating capabilities, as it is capable

  1. Airway pressure release ventilation reduces conducting airway micro-strain in lung injury.

    PubMed

    Kollisch-Singule, Michaela; Emr, Bryanna; Smith, Bradford; Ruiz, Cynthia; Roy, Shreyas; Meng, Qinghe; Jain, Sumeet; Satalin, Joshua; Snyder, Kathy; Ghosh, Auyon; Marx, William H; Andrews, Penny; Habashi, Nader; Nieman, Gary F; Gatto, Louis A

    2014-11-01

    Improper mechanical ventilation can exacerbate acute lung damage, causing a secondary ventilator-induced lung injury (VILI). We hypothesized that VILI can be reduced by modifying specific components of the ventilation waveform (mechanical breath), and we studied the impact of airway pressure release ventilation (APRV) and controlled mandatory ventilation (CMV) on the lung micro-anatomy (alveoli and conducting airways). The distribution of gas during inspiration and expiration and the strain generated during mechanical ventilation in the micro-anatomy (micro-strain) were calculated. Rats were anesthetized, surgically prepared, and randomized into 1 uninjured control group (n = 2) and 4 groups with lung injury: APRV 75% (n = 2), time at expiration (TLow) set to terminate appropriately at 75% of peak expiratory flow rate (PEFR); APRV 10% (n = 2), TLow set to terminate inappropriately at 10% of PEFR; CMV with PEEP 5 cm H2O (PEEP 5; n = 2); or PEEP 16 cm H2O (PEEP 16; n = 2). Lung injury was induced in the experimental groups by Tween lavage and ventilated with their respective settings. Lungs were fixed at peak inspiration and end expiration for standard histology. Conducting airway and alveolar air space areas were quantified and conducting airway micro-strain was calculated. All lung injury groups redistributed inspired gas away from alveoli into the conducting airways. The APRV 75% minimized gas redistribution and micro-strain in the conducting airways and provided the alveolar air space occupancy most similar to control at both inspiration and expiration. In an injured lung, APRV 75% maintained micro-anatomic gas distribution similar to that of the normal lung. The lung protection demonstrated in previous studies using APRV 75% may be due to a more homogeneous distribution of gas at the micro-anatomic level as well as a reduction in conducting airway micro-strain. Copyright © 2014 American College of Surgeons. All rights reserved.

  2. Instrumentation for Monitoring Breath Biomarkers for Diagnosis of Health Condition, Toxic Exposure and Disease

    DTIC Science & Technology

    2007-12-01

    Implement a simple system for pH probe calibration. 4. Development of the necessary electronics functionality for the continuous EBC pH monitoring system...Implement a simple system for pH probe calibration. 4. Development of the necessary electronics functionality for the continuous EBC pH monitoring...ventilator required special attachments to the PEEP value. The proven ability of the continuous pH condensimetry device to function robustly alongside

  3. Effect of mechanical ventilation on intra-abdominal pressure in critically ill patients without other risk factors for abdominal hypertension: an observational multicenter epidemiological study

    PubMed Central

    2012-01-01

    Background Mechanical ventilation (MV) is considered a predisposing factor for increased intra-abdominal pressure (IAP), especially when positive end-expiratory pressure (PEEP) is applied or in the presence of auto-PEEP. So far, no prospective data exists on the effect of MV on IAP. The study aims to look on the effects of MV on IAP in a group of critically ill patients with no other risk factors for intra-abdominal hypertension (IAH). Methods An observational multicenter study was conducted on a total of 100 patients divided into two groups: 50 patients without MV and 50 patients with MV. All patients were admitted to the intensive care units of the Medical and Surgical Research Centre, the Carlos J. Finlay Hospital, the Julio Trigo University Hospital, and the Calixto García Hospital, in Havana, Cuba between July 2000 and December 2004. The IAP was measured twice daily on admission using a standard transurethral technique. IAH was considered if IAP was greater than 12 mmHg. Correlations were made between IAP and body mass index (BMI), diagnostic category, gender, age, and ventilatory parameters. Results The mean IAP in patients on MV was 6.7 ± 4.1 mmHg and significantly higher than in patients without MV (3.6 ± 2.4 mmHg, p < 0.0001). This difference was maintained regardless of gender, age, BMI, and diagnosis. The use of MV and BMI were independent predictors for IAH for the whole population, while male gender, assisted ventilation mode, and the use of PEEP were independent factors associated with IAH in patients on MV. Conclusions In this study, MV was identified as an independent predisposing factor for the development of IAH. Critically ill patients, which are on MV, present with higher IAP values on admission and should be monitored very closely, especially if PEEP is applied, even when they have no other apparent risk factors for IAH. PMID:23281625

  4. Controlling mechanical ventilation in acute respiratory distress syndrome with fuzzy logic.

    PubMed

    Nguyen, Binh; Bernstein, David B; Bates, Jason H T

    2014-08-01

    The current ventilatory care goal for acute respiratory distress syndrome (ARDS) and the only evidence-based approach for managing ARDS is to ventilate with a tidal volume (VT) of 6 mL/kg predicted body weight (PBW). However, it is not uncommon for some caregivers to feel inclined to deviate from this strategy for one reason or another. To accommodate this inclination in a rationalized manner, we previously developed an algorithm that allows for VT to depart from 6 mL/kg PBW based on physiological criteria. The goal of the present study was to test the feasibility of this algorithm in a small retrospective study. Current values of peak airway pressure, positive end-expiratory pressure (PEEP), and arterial oxygen saturation are used in a fuzzy logic algorithm to decide how much VT should differ from 6 mL/kg PBW and how much PEEP should change from its current setting. We retrospectively tested the predictions of the algorithm against 26 cases of decision making in 17 patients with ARDS. Differences between algorithm and physician VT decisions were within 2.5 mL/kg PBW, except in 1 of 26 cases, and differences between PEEP decisions were within 2.5 cm H2O, except in 3 of 26 cases. The algorithm was consistently more conservative than physicians in changing VT but was slightly less conservative when changing PEEP. Within the limits imposed by a small retrospective study, we conclude that our fuzzy logic algorithm makes sensible decisions while at the same time keeping practice close to the current ventilatory care goal. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. CONTROLLING MECHANICAL VENTILATION IN ARDS WITH FUZZY LOGIC

    PubMed Central

    Nguyen, Binh; Bernstein, David B.; Bates, Jason H.T.

    2014-01-01

    Purpose The current ventilatory care goal for acute respiratory distress syndrome (ARDS), and the only evidence-based approach for managing ARDS, is to ventilate with a tidal volume (VT) of 6 ml/kg predicted body weight (PBW). However, it is not uncommon for some caregivers to feel inclined to deviate from this strategy for one reason or another. To accommodate this inclination in a rationalized manner, we previously developed an algorithm that allows for VT to depart from 6 ml/kg PBW based on physiological criteria. The goal of the present study was to test the feasibility of this algorithm in a small retrospective study. Materials and Methods Current values of peak airway pressure (PAP), positive end-expiratory pressure (PEEP) and arterial oxygen saturation (SaO2) are used in a fuzzy logic algorithm to decide how much VT should differ from 6 ml/kg PBW and how much PEEP should change from its current setting. We retrospectively tested the predictions of the algorithm against 26 cases of decision making in 17 patients with ARDS. Results Differences between algorithm and physician VT decisions were within 2.5 ml/kg PBW except in 1 of 26 cases, and differences between PEEP decisions were within 2.5 cm H2O except in 3 of 26 cases. The algorithm was consistently more conservative than physicians in changing VT, but was slightly less conservative when changing PEEP. Conclusions Within the limits imposed by a small retrospective study, we conclude that our fuzzy logic algorithm makes sensible decisions while at the same time keeping practice close to the current ventilatory care goal. PMID:24721387

  6. Mortality and pulmonary mechanics in relation to respiratory system and transpulmonary driving pressures in ARDS.

    PubMed

    Baedorf Kassis, Elias; Loring, Stephen H; Talmor, Daniel

    2016-08-01

    The driving pressure of the respiratory system has been shown to strongly correlate with mortality in a recent large retrospective ARDSnet study. Respiratory system driving pressure [plateau pressure-positive end-expiratory pressure (PEEP)] does not account for variable chest wall compliance. Esophageal manometry can be utilized to determine transpulmonary driving pressure. We have examined the relationships between respiratory system and transpulmonary driving pressure, pulmonary mechanics and 28-day mortality. Fifty-six patients from a previous study were analyzed to compare PEEP titration to maintain positive transpulmonary end-expiratory pressure to a control protocol. Respiratory system and transpulmonary driving pressures and pulmonary mechanics were examined at baseline, 5 min and 24 h. Analysis of variance and linear regression were used to compare 28 day survivors versus non-survivors and the intervention group versus the control group, respectively. At baseline and 5 min there was no difference in respiratory system or transpulmonary driving pressure. By 24 h, survivors had lower respiratory system and transpulmonary driving pressures. Similarly, by 24 h the intervention group had lower transpulmonary driving pressure. This decrease was explained by improved elastance and increased PEEP. The results suggest that utilizing PEEP titration to target positive transpulmonary pressure via esophageal manometry causes both improved elastance and driving pressures. Treatment strategies leading to decreased respiratory system and transpulmonary driving pressure at 24 h may be associated with improved 28 day mortality. Studies to clarify the role of respiratory system and transpulmonary driving pressures as a prognosticator and bedside ventilator target are warranted.

  7. Continuous on-line measurements of respiratory system, lung and chest wall mechanics during mechanic ventilation.

    PubMed

    Kárason, S; Søndergaard, S; Lundin, S; Stenqvist, O

    2001-08-01

    We present a concept of on-line, manoeuvre-free monitoring of respiratory mechanics during dynamic conditions, displaying calculated alveolar pressure/volume curves continuously and separating lung and chest wall mechanics. Prospective observational study. Intensive care unit of a university hospital. Ten ventilator-treated patients with acute lung injury. Different positive end-expiratory pressure (PEEP) and tidal volumes, low flow inflation. Previously validated methods were used to present a single-value dynostatic compliance for the whole breath and a dynostatic volume-dependent initial, middle and final compliance within the breath. A high individual variation of respiratory mechanics was observed. Reproducibility of repeated measurements was satisfactory (coefficients of variations for dynostatic volume-dependent compliance: < or =9.2% for total respiratory system, < or =18% for lung). Volume-dependent compliance showed a statistically significant pattern of successively decreasing compliance from the initial segment through the middle and final parts within each breath at all respiratory settings. This pattern became more prominent with increasing PEEP and tidal volume, indicating a greater distension of alveoli. No lower inflection point (LIP) was seen in patients with respiratory rate 20/min and PEEP at 4 cmH2O. A trial with low flow inflation in four of the patients showed formation of a LIP in three of them and an upper inflection in one. The monitoring concept revealed a constant pattern of successively decreasing compliance within each breath, which became more prominent with increasing PEEP and tidal volume. The monitoring concept offers a simple and reliable method of monitoring respiratory mechanics during ongoing ventilator treatment.

  8. Lung volume assessments in normal and surfactant depleted lungs: agreement between bedside techniques and CT imaging.

    PubMed

    Albu, Gergely; Petak, Ferenc; Zand, Tristan; Hallbäck, Magnus; Wallin, Mats; Habre, Walid

    2014-01-01

    Bedside assessment of lung volume in clinical practice is crucial to adapt ventilation strategy. We compared bedside measures of lung volume by helium multiple-breath washout technique (EELVMBW,He) and effective lung volume based on capnodynamics (ELV) to those assessed from spiral chest CT scans (EELVCT) under different PEEP levels in control and surfactant-depleted lungs. Lung volume was assessed in anaesthetized mechanically ventilated rabbits successively by measuring i) ELV by analyzing CO2 elimination traces during the application of periods of 5 consecutive alterations in inspiratory/expiratory ratio (1:2 to 1.5:1), ii) measuring EELVMBW,He by using helium as a tracer gas, and iii) EELVCT from CT scan images by computing the normalized lung density. All measurements were performed at PEEP of 0, 3 and 9 cmH2O in random order under control condition and following surfactant depletion by whole lung lavage. Variables obtained with all techniques followed sensitively the lung volume changes with PEEP. Excellent correlation and close agreement was observed between EELVMBW,He and EELVCT (r = 0.93, p < 0.0001). ELV overestimated EELVMBW,He and EELVCT in normal lungs, whereas this difference was not evidenced following surfactant depletion. These findings resulted in somewhat diminished but still significant correlations between ELV and EELVCT (r = 0.58, p < 0.001) or EELVMBW,He (0.76, p < 0.001) and moderate agreements. Lung volume assessed with bedside techniques allow the monitoring of the changes in the lung aeration with PEEP both in normal lungs and in a model of acute lung injury. Under stable pulmonary haemodynamic condition, ELV allows continuous lung volume monitoring, whereas EELVMBW,He offers a more accurate estimation, but intermittently.

  9. Risk Factors for the Mortality of Pneumocystis jirovecii Pneumonia in Non-HIV Patients Who Required Mechanical Ventilation: A Retrospective Case Series Study.

    PubMed

    Kotani, Toru; Katayama, Shinshu; Miyazaki, Yuya; Fukuda, Satoshi; Sato, Yoko; Ohsugi, Koichi

    2017-01-01

    The risk factors for the mortality rate of Pneumocystis jirovecii pneumonia (PCP) who required mechanical ventilation (MV) remained unknown. A retrospective chart review was performed of all PCP patients admitted to our intensive care unit and treated for acute hypoxemic respiratory failure to assess the risk factors for the high mortality. Twenty patients without human immunodeficiency virus infection required mechanical ventilation; 19 received noninvasive ventilation; and 11 were intubated. PEEP was incrementally increased and titrated to maintain FIO2 as low as possible. No mandatory ventilation was used. Sixteen patients (80%) survived. Pneumothorax developed in one patient with rheumatoid arthritis (RA). Median PEEP level in the first 5 days was 10.0 cmH2O and not associated with death. Multivariate analysis showed the association of incidence of interstitial lung disease and increase in serum KL-6 with 90-day mortality. We found MV strategies to prevent pneumothorax including liberal use of noninvasive ventilation, and PEEP titration and disuse of mandatory ventilation may improve mortality in this setting. Underlying disease of interstitial lung disease was a risk factor and KL-6 may be a useful predictor associated with mortality in patients with RA. These findings will need to be validated in larger studies.

  10. Design and Construction of a Microcontroller-Based Ventilator Synchronized with Pulse Oximeter.

    PubMed

    Gölcük, Adem; Işık, Hakan; Güler, İnan

    2016-07-01

    This study aims to introduce a novel device with which mechanical ventilator and pulse oximeter work in synchronization. Serial communication technique was used to enable communication between the pulse oximeter and the ventilator. The SpO2 value and the pulse rate read on the pulse oximeter were transmitted to the mechanical ventilator through transmitter (Tx) and receiver (Rx) lines. The fuzzy-logic-based software developed for the mechanical ventilator interprets these values and calculates the percentage of oxygen (FiO2) and Positive End-Expiratory Pressure (PEEP) to be delivered to the patient. The fuzzy-logic-based software was developed to check the changing medical states of patients and to produce new results (FiO2 ve PEEP) according to each new state. FiO2 and PEEP values delivered from the ventilator to the patient can be calculated in this way without requiring any arterial blood gas analysis. Our experiments and the feedbacks from physicians show that this device makes it possible to obtain more successful results when compared to the current practices.

  11. Swift recovery of severe hypoxemic pneumonia upon morbid obesity.

    PubMed

    Galland, C; Ferrand, F X; Cividjian, A; Sergent, B; Pichot, C; Ghignone, M; Quintin, L

    2014-01-01

    A morbidly obese (body mass index = 55.5) female patient presented with severe hypoxemic community acquired pneumonia [PaO2/FiO2 (P/F) = 57] with primarily right basal atelectasis, but without bilateral opacities in the upper lobes on the chest X-ray. Major O2 desaturations led the nurses to object to moving the patient to the prone position: muscle relaxation combined to prone position was impossible. Therefore, stringent 60 degrees reverse Trendelenburg legs down position was constantly maintained during mechanical ventilation through the endotracheal tube, using low pressure support (pressure support = 5-10 cmH2O) and high positive end-expiratory pressure (PEEP). PEEP was progressively increased to 20 cmH2O, and little or no sedation was used. A P/F improvement from 57 to 200 over three days allowed removing the tracheal tube. The patient was discharged 13 days after admission. In this paper, the use of high PEEP in the context of morbid obesity, and low pressure support are discussed.

  12. Site of deposition and factors affecting clearance of aerosolized solute from canine lungs

    SciTech Connect

    Rizk, N.W.; Luce, J.M.; Hoeffel, J.M.; Price, D.C.; Murray, J.F.

    1984-01-01

    The influence of several factors on lung solute clearance using aerosolized /sup 99m/Tc-diethylenetriaminepentaacetate was determined. The authors used a jet nebulizer-plate separator-balloon system to generate particles with an activity median aerodynamic diameter of 1.1 ..mu..m, administered the aerosol in a standard fashion, and determined clearance half times (t/sub 1/2/) with a gamma-scintillation camera. The following serial studies were performed in five anesthetized, paralyzed, intubated, mechanically ventilated dogs: (1) control, with ventilatory frequency (f) = 15 breaths/min and tidal volume (V/sub T/) = 15 ml/kg during solute clearance; (2) repeat control, for reproducibility; (3) increased frequency, with f = 25 breaths/min and V/sub T/ = 10 ml/kg; (4) positive end-expiratory pressure (PEEP) of 10 cmH/sub 2/O; (5) unilateral pulmonary arterial occlusion (PAO); and (6) bronchial arterial occlusion (BAO). Control t/sub 1/2/ was 25 +/- 5 min and did not change in the repeat control, increased frequency, or BAO experiments. PEEP markedly decreased t/sub 1/2/ to 13 +/- 3 min (P < 0.01), and PAO increased it to 37 +/- 6 min (P < 0.05). We conclude that clearance from the lungs by our method is uninfluenced by increased frequency, increases markedly with PEEP, and depends on pulmonary, not bronchial, blood flow.

  13. Lung mechanical changes following bronchoaspiration in a porcine model: differentiation of direct and indirect mechanisms.

    PubMed

    Fodor, Gergely H; Peták, Ferenc; Erces, Dániel; Balogh, Adám L; Babik, Barna

    2014-08-01

    Bronchoaspiration results in local deterioration of lung function through direct damage and/or indirect systemic effects related to neurohumoral pathways. We distinguished these effects by selectively intubating the two main bronchi in pigs while a PEEP of 4 or 10cm H2O was maintained. Gastric juice was instilled only into the right lung. Lung mechanical and ventilation defects were assessed by measuring unilateral pulmonary input impedance (ZL,s) and the third phase slope of the capnogram (SIII) for each lung side separately before the aspiration and for 120min thereafter. Marked transient elevations in ZL,s parameters and SIII were observed in the affected lung after aspiration. Elevating PEEP did not affect these responses in the ZL,s parameters, whereas it prevented the SIII increases. None of these indices changed in the intact left lung. These findings furnish evidence of the predominance of the local direct damage over the indirect systemic effects in the development of the deterioration of lung function, and demonstrate the benefit of an initially elevated PEEP following aspiration.

  14. Positive expiratory pressure as a method for preventing the impairment of attentional processes by hypoxia.

    PubMed

    Stivalet, P; Leifflen, D; Poquin, D; Savourey, G; Launay, J C; Barraud, P A; Raphel, C; Bittel, J

    2000-04-01

    This study investigated the effects of hypoxia on parallel/preattentional and serial/attentional processes in early vision, and the use of a positive-end-expiratory-pressure (PEEP) to prevent the impairment in performance. Twenty-one subjects were submitted to an 8-h hypoxia exposure in a hypobaric chamber (4500 m, 589 hPa, 22 degrees C), both with and without a 5-cm H2O PEEP. Subjects carried out a visual search task consisting of detecting a target among distractors in normoxia, in acute and in prolonged hypoxia. Conjointly their sensitivity to acute mountain sickness (AMS) was scored through the Lake Louise AMS scoring system. Results showed that prolonged hypoxia slowed serial/attentional processing whereas parallel/preattentional processes were not impaired either by acute or by prolonged hypoxia. PEEP prevented serial/attentional processes from slowing and those effects were more clearly observed in the AMS sensitive subjects with respect to the AMS insensitive subjects. These results suggest that the slowing induced by prolonged hypoxia is specific to an early visual process that pilots the scanning of an attentional spotlight throughout the visual field.

  15. [Utility of recruitment maneuvers (con)].

    PubMed

    Ochagavia, A; Blanch, L; Lopez-Aguilar, J

    2009-04-01

    A reduction in both total lung volume and in lung parenchyma useful for gas exchange has been observed in ARDS patients. Applying an appropriate ventilatory pattern that includes PEEP can open up collapsed areas of the lung to aeration, thus ensuring a more homogeneous distribution of air in the lung. However, the heterogeneous patterns observed in patients with ARDS vary widely in their response to ventilation with PEEP. Recruitment maneuvers (RM) have been proposed as an adjuvant treatment to mechanical ventilation to re-expand collapsed lung tissue in ARDS. Nevertheless, it is unclear whether RM are useful when patients are ventilated with high PEEP or when they have fibrosis, stiff chest wall, or hypovolemia, among other conditions. Likewise, decisions about RM must take into account not only their short- and long-term efficacy and reversibility, but also possible adverse effects derived from the high pressures reached during RM, including barotrauma, hemodynamic alterations, reduced systolic volume and aortic flow, and difficulties in venous return, as well as the possibility of bacterial translocation to the bloodstream or other organs. This article review the effects of RM as adjuvant treatment to mechanical ventilation in ARDS patients and discuss its efficacy and potential benefits as well as the different interactions that RM can have with the diverse conditions that can be associated to ARDS.

  16. Effect of positive end-expiratory pressure on acoustic wave propagation in experimental porcine lung injury.

    PubMed

    Räsänen, Jukka; Nemergut, Michael E; Gavriely, Noam

    2015-03-01

    To evaluate the effect of positive end-expiratory pressure (PEEP) on sound propagation through injured lungs, we injected a multifrequency broad-band sound signal into the airway of eight anesthetized, intubated and mechanically ventilated pigs, while recording transmitted sound at three locations bilaterally on the chest wall. Oleic acid injections effected a severe pulmonary oedema predominately in the dependent lung regions, with an average increase in venous admixture from 19 ± 15 to 59 ± 14% (P < 0.001), and a reduction in dynamic respiratory system compliance from 34 ± 7 to 14 ± 4 ml cmH2 O(-1) (P < 0.001). A concomitant decrease in sound transit time was seen in the dependent lung regions (P < 0.05); no statistically significant change occurred in the lateral or non-dependent areas. The application of PEEP resulted in a decrease in venous admixture, increase in respiratory system compliance and return of the sound transit time to pre-injury levels in the dependent lung regions. Our results indicate that sound transmission velocity increases in lung tissue affected by permeability-type pulmonary oedema in a manner reversible during alveolar recruitment with PEEP.

  17. [Mechanical ventilation during thoracic anesthesia].

    PubMed

    Valenza, F

    1999-05-01

    Aim of the study was to test individual mechanical and functional responses to open chest lateral decubitus during one lung ventilation. We measured dependent lung pressure volume (P-V) curves of 19 patients during supine and lateral decubitus. We found that patients characterized by high FEV1 developed greater changes in P-V curve shape than those characterized by low FEV1. Based on these results we decided to test a ventilation strategy characterized by the use of ZEEP or PEEP = 10 cm H2O applied to the dependent lung. In a preliminary set of patients stratified by FEV1 we found that PEEP deteriorated PaO2/FiO2 in patients with low FEV1, while there was a trend towards improvement in patients with high FEV1. It is possible that dependent lung PEEP counteracts atelectasias in normal lungs, while it may divert blood flow or create dead space in patients with sick and stiff lungs. We conclude that during one lung ventilation in open chest lateral decubitus, ventilatory setting need to be individually tailored.

  18. Different effects of surfactant proteins B and C - implications for development of synthetic surfactants.

    PubMed

    Curstedt, Tore; Johansson, Jan

    2010-06-01

    Treatment of premature newborn rabbits with synthetic surfactants containing a surfactant protein C analogue in a simple phospholipid mixture gives similar tidal volumes as treatment with poractant alfa (Curosurf(R)) but ventilation with a positive end-expiratory pressure (PEEP) is needed for this synthetic surfactant to stabilize the alveoli at end-expiration. The effect on lung gas volumes seems to depend on the structure of the peptide since treatment with a synthetic surfactant containing the 21-residue peptide (LysLeu(4))(4)Lys (KL(4)) gives low lung gas volumes in experiments also performed with PEEP. Surfactant preparations containing both surfactant proteins B and C or their analogues prevent alveolar collapse at end-expiration even if ventilated without PEEP. Treatment of premature newborn rabbits with different natural surfactants indicates that both the lipid composition and the proteins are important in order to stabilize the alveoli at end-expiration. Synthetic surfactants containing two peptides may be able to replace natural surfactants within the near future but more trials need to be performed before any conclusion can be drawn about the ideal composition of this new generation of synthetic surfactants. Copyright 2010 S. Karger AG, Basel.

  19. Respirator triggering of electron beam computed tomography (EBCT): evaluation of dynamic changes during mechanical expiration in the traumatized patient

    NASA Astrophysics Data System (ADS)

    Recheis, Wolfgang A.; Kleinsasser, Axel; Hatschenberger, Robert; Knapp, Rudolf; zur Nedden, Dieter; Hoermann, Christoph

    1999-05-01

    The purpose of this project is to evaluate the dynamic changes during expiration at different levels of positive end- expiratory pressure (PEEP) in the ventilated patient. We wanted to discriminate between normal lung function and acute respiratory distress syndrome (ARDS). After approval by the local Ethic Committee we studied two ventilated patients: (1) with normal lung function; (2) ARDS). We used the 50 ms scan mode of the EBCT. The beam was positioned 1 cm above the diaphragm. The table position remained unchanged. An electronic trigger was developed, that utilizes the respirators synchronizing signal to start the EBCT at the onset of expiration. During controlled mechanical expiration at two levels of PEEP (0 and 15 cm H2O), pulmonary aeration was rated as: well-aerated (-900HU/-500HU), poorly- aerated (-500HU/-100HU) and non-aerated (-100HU/+100HU). Pathological and normal lung function showed different dynamic changes (FIG.4-12). The different PEEP levels resulted in a significant change of pulmonary aeration in the same patient. Although we studied only a very limited number of patients, respirator triggered EBCT may be accurate in discriminating pathological changes due to the abnormal lung function in the mechanically ventilated patient.

  20. The effect of lung deflation on the position of the pleura during subclavian vein cannulation in infants receiving mechanical ventilation: an ultrasound study.

    PubMed

    Jang, Y-E; Lee, J-H; Park, Y-H; Byon, H-J; Kim, H-S; Kim, C-S; Kim, J-T

    2013-10-01

    We evaluated the effect of lung deflation on the relative position of the pleura compared with a reference line during supra- and infraclavicular approaches to the right subclavian vein. The reference line was drawn relative to the predicted pathway of the needle. The distances between the pleura and the reference line for supra- and infraclavicular approaches were measured during inspiration and expiration in 41 infants. Measurements were repeated with the application of 5 cmH2O positive end-expiratory pressure (PEEP) and in the Trendelenburg position. Lung deflation during the supraclavicular approach significantly decreased the volume of lung crossing the reference line by a median (IQR [range]) of 1.0 (0.6 to 1.3 [0.0 to 4.8]) mm, p < 0.001, irrespective of the application of PEEP or patient position. However, during the infraclavicular approach, lung deflation showed no change in the distance of the pleura from the reference line regardless of PEEP or patient position. We conclude that lung deflation moves the lung apex caudally and can reduce the potential risk of pneumothorax during a supraclavicular approach to the right subclavian vein in infants.

  1. Recruitment maneuvers in acute respiratory distress syndrome and during general anesthesia.

    PubMed

    Chiumello, Davide; Algieri, Ilaria; Grasso, Salvatore; Terragni, Pierpaolo; Pelosi, Paolo

    2016-02-01

    The use of low tidal volume ventilation and low to moderate positive end-expiratory pressure (PEEP) levels is a widespread strategy to ventilate patients with non-injured lungs during general anesthesia and in intensive care as well with mild to moderate acute respiratory distress syndrome (ARDS). Higher PEEP levels have been recommended in severe ARDS. Due to the presence of alveolar collapse, recruitment maneuvers (RMs) by causing a transient elevation in airway pressure (i.e. transpulmonary pressure) have been suggested to improve lung inflation in non-inflated and poorly-inflated lung regions. Various types of RMs such as sustained inflation at high pressure, intermittent sighs and stepwise increases of PEEP and/or airway plateau inspiratory pressure have been proposed. The use of RMs has been associated with mixed results in terms of physiological and clinical outcomes. The optimal method for RMs has not yet been identified. The use of RMs is not standardized and left to the individual physician based on his/her experience. Based on the same grounds, RMs have been proposed to improve lung aeration during general anesthesia. The aim of this review was to present the clinical evidence supporting the use of RMs in patients with ARDS and during general anesthesia and as well their potential biological effects in experimental models of acute lung injury.

  2. Pulmonary rapidly adapting receptor stimulation does not increase airway resistance in anesthetized rabbits.

    PubMed

    Yu, J; Zhang, J F; Roberts, A M; Collins, L C; Fletcher, E C

    1999-09-01

    In open-chest artificially ventilated rabbits, removal followed by replacement of positive end-expiratory pressure (PEEP maneuver) favors stimulation of airway rapidly adapting receptors (RARs). The purpose of the present study was to determine whether activation of RARs can cause bronchoconstriction. We measured airway pressure, airflow, and tidal volume, and calculated dynamic lung compliance and total lung resistance. PEEP maneuver increased airway pressure swings (16.4 +/- 4% above control; p = 0.0016) and decreased compliance (to 84.8 +/- 2.8% of control; p = 0.0002) without changing resistance (108.0 +/- 4.4% of control; p = 0.85). On the other hand, the resistance increased greatly (93 +/- 13%, p < 0.01) after intravenous injection of acetylcholine or electrical stimulation of vagal efferents, indicating that our system could detect increases in the resistance. In a separate group, we stimulated RARs by stroking the trachea with a cotton tip (tickling), tickling produced cough, manifested by increased pressure and flow without resistance changing. These changes were abolished after paralysis with succinylcholine. Because we did not detect an increase in airflow resistance during activation of RARs by the PEEP maneuver and tickling, we conclude that increase in resistance may not be an important reflex component of airway RARs.

  3. Heated Humidified High-Flow Nasal Oxygen in Adults: Mechanisms of Action and Clinical Implications.

    PubMed

    Spoletini, Giulia; Alotaibi, Mona; Blasi, Francesco; Hill, Nicholas S

    2015-07-01

    Traditionally, nasal oxygen therapy has been delivered at low flows through nasal cannulae. In recent years, nasal cannulae designed to administer heated and humidified air/oxygen mixtures at high flows (up to 60 L/min) have been gaining popularity. These high-flow nasal cannula (HFNC) systems enhance patient comfort and tolerance compared with traditional high-flow oxygenation systems, such as nasal masks and nonrebreathing systems. By delivering higher flow rates, HFNC systems are less apt than traditional oxygenation systems to permit entrainment of room air during patient inspiration. Combined with the flushing of expired air from the upper airway during expiration, these mechanisms assure more reliable delivery of high Fio2 levels. The flushing of upper airway dead space also improves ventilatory efficiency and reduces the work of breathing. HFNC also generates a positive end-expiratory pressure (PEEP), which may counterbalance auto-PEEP, further reducing ventilator work; improve oxygenation; and provide back pressure to enhance airway patency during expiration, permitting more complete emptying. HFNC has been tried for multiple indications, including secretion retention, hypoxemic respiratory failure, and cardiogenic pulmonary edema, to counterbalance auto-PEEP in patients with COPD and as prophylactic therapy or treatment of respiratory failure postsurgery and postextubation. As of yet, very few high-quality studies have been published evaluating these indications, so recommendations regarding clinical applications of HFNC remain tentative.

  4. Mechanical ventilation in abdominal surgery.

    PubMed

    Futier, E; Godet, T; Millot, A; Constantin, J-M; Jaber, S

    2014-01-01

    One of the key challenges in perioperative care is to reduce postoperative morbidity and mortality. Patients who develop postoperative morbidity but survive to leave hospital have often reduced functional independence and long-term survival. Mechanical ventilation provides a specific example that may help us to shift thinking from treatment to prevention of postoperative complications. Mechanical ventilation in patients undergoing surgery has long been considered only as a modality to ensure gas exchange while allowing maintenance of anesthesia with delivery of inhaled anesthetics. Evidence is accumulating, however, suggesting an association between intraoperative mechanical ventilation strategy and postoperative pulmonary function and clinical outcome in patients undergoing abdominal surgery. Non-protective ventilator settings, especially high tidal volume (VT) (>10-12mL/kg) and the use of very low level of positive end-expiratory pressure (PEEP) (PEEP<5cmH2O) or no PEEP, may cause alveolar overdistension and repetitive tidal recruitment leading to ventilator-associated lung injury in patients with healthy lungs. Stimulated by previous findings in patients with acute respiratory distress syndrome, the use of lower tidal volume ventilation is becoming increasingly more common in the operating room. However, lowering tidal volume, though important, is only part of the overall multifaceted approach of lung protective mechanical ventilation. In this review, we aimed at providing the most recent and relevant clinical evidence regarding the use of mechanical ventilation in patients undergoing abdominal surgery.

  5. Atelectasis and perioperative pulmonary complications in high-risk patients.

    PubMed

    Tusman, Gerardo; Böhm, Stephan H; Warner, David O; Sprung, Juraj

    2012-02-01

    This review evaluates the link between perioperative lung atelectasis and postoperative pulmonary complications (PPCs) and how appropriate ventilatory strategies could mitigate this problem. Atelectasis may contribute to serious PPCs including respiratory failure and pneumonia. Ventilator settings during anesthesia, especially with higher tidal volumes (V(T)) (>10  ml/kg), high plateau pressures (>30  cmH(2)O) and without positive end expiratory pressure (PEEP), are associated with lung injury even in healthy, but partially collapsed, lungs. These injurious settings may cause inflammation which is related to repetitive tidal recruitment and alveolar overdistension. Such ventilator-induced lung injury can be attenuated by using low V(T) and plateau pressures at sufficient PEEP, ideally after actively recruiting the lungs. The use of continuous positive airway pressure and 'lower' FiO(2) during anesthetic induction, intraoperative use of lower FiO(2), low V(T), lung recruitment and PEEP ('protective ventilatory strategy') in conjunction with postoperative early mobilization, breathing exercises and continuous positive airway pressure may help in maintaining lung aeration, thereby decreasing hypoxemia and risk of postoperative pneumonia. Evidence is accumulating suggesting that the incidence of postoperative pulmonary complication could be markedly reduced if an 'open lung' philosophy was adopted for the perioperative care. A goal-directed ventilatory approach keeping an 'open lung' condition during the perioperative period may reduce the incidence of PPCs.

  6. Lung recruitment maneuver during volume guarantee ventilation of preterm infants with acute respiratory distress syndrome.

    PubMed

    Castoldi, Francesca; Daniele, Irene; Fontana, Paola; Cavigioli, Francesco; Lupo, Enrica; Lista, Gianluca

    2011-08-01

    Preterm infants need the achievement of adequate lung volume. Lung recruitment maneuver (LRM) is applied during high-frequency oscillatory ventilation. We investigated the effect of an LRM with positive end-expiratory pressure (PEEP) on oxygenation and outcomes in infants conventionally ventilated for respiratory distress syndrome (RDS). Preterm infants in assisted controlled ventilation+volume guarantee for RDS after surfactant randomly received an LRM (group A) or did not (group B). LRM entailed increments of 0.2 cm H (2)O PEEP every 5 minutes, until fraction of inspired oxygen (Fi O(2))=0.25. Then PEEP was reduced and the lung volume was set on the deflation limb of the pressure/volume curve. When saturation of peripheral oxygen fell and Fi O(2) rose, we reincremented PEEP until Sp O(2) became stable. Group A ( N=10) and group B ( N=10) infants were similar: gestational age 25 ± 2 versus 25 ± 2 weeks; body weight 747 ± 233 versus 737 ± 219 g; clinical risk index for babies 9.8 versus 8.1; initial Fi O(2) 56 ± 24 versus 52 ± 21, respectively. LRM began at 86 ± 69 minutes of age and lasted for 61 ± 18 minutes. Groups A and B showed different max PEEP during the first 12 hours of life (6.1 ± 0.3 versus 5.3 ± 0.3 cm H (2)O, P=0.00), time to lowest Fi O(2) (94 ± 24 versus 435 ± 221 minutes; P=0.000) and O(2) dependency (29 ± 12 versus 45 ± 17 days; P=0.04). No adverse events and no differences in the outcomes were observed. LRM led to the earlier lowest Fi O(2) of the first 12 hours of life and a shorter O (2) dependency.

  7. Quantitative imaging of alveolar recruitment with hyperpolarized gas MRI during mechanical ventilation

    PubMed Central

    Cereda, Maurizio; Emami, Kiarash; Kadlecek, Stephen; Xin, Yi; Mongkolwisetwara, Puttisarn; Profka, Harrilla; Barulic, Amy; Pickup, Stephen; Månsson, Sven; Wollmer, Per; Ishii, Masaru; Deutschman, Clifford S.

    2011-01-01

    The aim of this study was to assess the utility of 3He MRI to noninvasively probe the effects of positive end-expiratory pressure (PEEP) maneuvers on alveolar recruitment and atelectasis buildup in mechanically ventilated animals. Sprague-Dawley rats (n = 13) were anesthetized, intubated, and ventilated in the supine position (4He-to-O2 ratio: 4:1; tidal volume: 10 ml/kg, 60 breaths/min, and inspiration-to-expiration ratio: 1:2). Recruitment maneuvers consisted of either a stepwise increase of PEEP to 9 cmH2O and back to zero end-expiratory pressure or alternating between these two PEEP levels. Diffusion MRI was performed to image 3He apparent diffusion coefficient (ADC) maps in the middle coronal slices of lungs (n = 10). ADC was measured immediately before and after two recruitment maneuvers, which were separated from each other with a wait period (8–44 min). We detected a statistically significant decrease in mean ADC after each recruitment maneuver. The relative ADC change was −21.2 ± 4.1 % after the first maneuver and −9.7 ± 5.8 % after the second maneuver. A significant relative increase in mean ADC was observed over the wait period between the two recruitment maneuvers. The extent of this ADC buildup was time dependent, as it was significantly related to the duration of the wait period. The two postrecruitment ADC measurements were similar, suggesting that the lungs returned to the same state after the recruitment maneuvers were applied. No significant intrasubject differences in ADC were observed between the corresponding PEEP levels in two rats that underwent three repeat maneuvers. Airway pressure tracings were recorded in separate rats undergoing one PEEP maneuver (n = 3) and showed a significant relative difference in peak inspiratory pressure between pre- and poststates. These observations support the hypothesis of redistribution of alveolar gas due to recruitment of collapsed alveoli in presence of atelectasis, which was also supported by the

  8. Respiratory system mechanics in acute respiratory distress syndrome.

    PubMed

    Kallet, Richard H; Katz, Jeffrey A

    2003-09-01

    Respiratory mechanics research is important to the advancement of ARDS management. Twenty-eight years ago, research on the effects of PEEP and VT indicated that the lungs of ARDS patients did not behave in a manner consistent with homogenously distributed lung injury. Both Suter and colleagues] and Katz and colleagues reported that oxygenation continued to improve as PEEP increased (suggesting lung recruitment), even though static Crs decreased and dead-space ventilation increased (suggesting concurrent lung overdistension). This research strongly suggested that without VT reduction, the favorable effects of PEEP on lung recruitment are offset by lung overdistension at end-inspiration. The implications of these studies were not fully appreciated at that time, in part because the concept of ventilator-associated lung injury was in its nascent state. Ten years later. Gattinoni and colleagues compared measurements of static pressure-volume curves with FRC and CT scans of the chest in ARDS. They found that although PEEP recruits collapsed (primarily dorsal) lung segments, it simultaneously causes overdistension of non-dependent, inflated lung regions. Furthermore, the specific compliance of the aerated, residually healthy lung tissue is essentially normal. The main implication of these findings is that traditional mechanical ventilation practice was injecting excessive volumes of gas into functionally small lungs. Therefore, the emblematic low static Crs measured in ARDS reflects not only surface tension phenomena and recruitment of collapsed airspaces but also overdistension of the remaining healthy lung. The studies reviewed in this article support the concept that lung injury in ARDS is heterogeneously distributed, with resulting disparate mechanical stresses, and indicate the additional complexity from alterations in chest wall mechanics. Most of these studies, however, were published before lung-protective ventilation. Therefore, further studies are needed to

  9. Evaluation of noninvasive positive pressure ventilation after extubation from moderate positive end-expiratory pressure level in patients undergoing cardiovascular surgery: a prospective observational study.

    PubMed

    Suzuki, Takeshi; Kurazumi, Takuya; Toyonaga, Shinya; Masuda, Yuya; Morita, Yoshihisa; Masuda, Junichi; Kosugi, Shizuko; Katori, Nobuyuki; Morisaki, Hiroshi

    2014-01-01

    It remains to be clarified if the application of noninvasive positive pressure ventilation (NPPV) is effective after extubation in patients with hypoxemic respiratory failure who require the sufficient level of positive end-expiratory pressure (PEEP). This study was aimed at examining the effect and the safety of NPPV application following extubation in patients requiring moderate PEEP level for sufficient oxygenation after cardiovascular surgery. With institutional ethic committee approval, the patients ventilated invasively for over 48 h after cardiovascular surgery were enrolled in this study. The patients who failed the first spontaneous breathing trial (SBT) at 5 cmH2O of PEEP, but passed the second SBT at 8 cmH2O of PEEP, received NPPV immediately after extubation following our weaning protocol. Respiratory parameters (partial pressure of arterial oxygen tension to inspiratory oxygen fraction ratio: P/F ratio, respiratory ratio, and partial pressure of arterial carbon dioxide: PaCO2) 2 h after extubation were evaluated with those just before extubation as the primary outcome. The rate of re-intubation, the frequency of respiratory failure and intolerance of NPPV, the duration of NPPV, and the length of intensive care unit (ICU) stay were also recorded. While 51 postcardiovascular surgery patients were screened, 6 patients who met the criteria received NPPV after extubation. P/F ratio was increased significantly after extubation compared with that before extubation (325 ± 85 versus 245 ± 55 mmHg, p < 0.05). The other respiratory parameters did not change significantly. Re-intubation, respiratory failure, and intolerance of NPPV never occurred. The duration of NPPV and the length of ICU stay were 2.7 ± 0.7 (SD) and 7.5 (6 to 10) (interquartile range) days, respectively. While further investigation should be warranted, NPPV could be applied effectively and safely after extubation in patients requiring the moderate PEEP level after

  10. Dose-response comparisons of five lung surfactant factor (LSF) preparations in an animal model of adult respiratory distress syndrome (ARDS).

    PubMed

    Häfner, D; Beume, R; Kilian, U; Krasznai, G; Lachmann, B

    1995-06-01

    1. We have examined the effects of five different lung surfactant factor (LSF) preparations in the rat lung lavage model. In this model repetitive lung lavage leads to lung injury with some similarities to adult respiratory distress syndrome with poor gas exchange and protein leakage into the alveolar spaces. These pathological sequelae can be reversed by LSF instillation soon after lavage. 2. The tested LSF preparations were: two bovine: Survanta and Alveofact: two synthetic: Exosurf and a protein-free phospholipid based LSF (PL-LSF) and one Recombinant LSF at doses of 25, 50 and 100 mg kg-1 body weight and an untreated control group. 3. Tracheotomized rats (10-12 per dose) were pressure-controlled ventilated (Siemens Servo Ventilator 900C) with 100% oxygen at a respiratory rate of 30 breaths min-1, inspiration expiration ratio of 1:2, peak inspiratory pressure (PIP) of 28 cmH2O at positive end-expiratory pressure (PEEP) of 8 cmH2O. Two hours after LSF administration, PEEP and in parallel PIP was reduced from 8 to 6 (1st reduction), from 6 to 3 (2nd reduction) and from 3 to 0 cmH2O (3rd reduction). 4. Partial arterial oxygen pressure (PaO2, mmHg) at 5 min and 120 min after LSF administration and during the 2nd PEEP reduction (PaO2(PEEP23/3)) were used for statistical comparison. All LSF preparations caused a dose-dependent increase for the PaO2(120'), whereas during the 2nd PEEP reduction only bovine and recombinant LSF exhibited dose-dependency. Exosurf did not increase PaO2 after administration of the highest dose. At the highest dose Exosurf exerted no further improvement but rather a tendency to relapse. The bovine and the Recombinant LSF are superior to both synthetic LSFpreparations.5. In this animal model and under the described specific ventilatory settings, even between bovine LSFpreparations there are detectable differences that are pronounced when compared to synthetic LSFwithout any surfactant proteins. We conclude that the difference between bovine

  11. Effects of recruitment maneuver on atelectasis in anesthetized children.

    PubMed

    Tusman, Gerardo; Böhm, Stephan H; Tempra, Alejandro; Melkun, Fernando; García, Eduardo; Turchetto, Elsio; Mulder, Paul G H; Lachmann, Burkhard

    2003-01-01

    General anesthesia is known to promote atelectasis formation. High inspiratory pressures are required to reexpand healthy but collapsed alveoli. However, in the absence of positive end-expiratory pressure (PEEP), reexpanded alveoli collapse again. Using magnetic resonance imaging, the impact of an alveolar recruitment strategy on the amount and distribution of atelectasis was tested. The authors prospectively randomized 24 children who met American Society of Anesthesiologists physical status I or II criteria, were aged 6 months-6 yr, and were undergoing cranial magnetic resonance imaging into three groups. After anesthesia induction, in the alveolar recruitment strategy (ARS) group, an alveolar recruitment maneuver was performed by manually ventilating the lungs with a peak airway pressure of 40 cm H2O and a PEEP of 15 cm H2O for 10 breaths. PEEP was then reduced to and kept at 5 cm H2O. The continuous positive airway pressure (CPAP) group received 5 cm H2O of continuous positive airway pressure without recruitment. The zero end-expiratory pressure (ZEEP) group received neither PEEP nor the recruitment maneuver. All patients breathed spontaneously during the procedure. After cranial magnetic resonance imaging, thoracic magnetic resonance imaging was performed. The atelectatic volume (median, first and third standard quartiles) detected in the ZEEP group was 1.25 (0.75-4.56) cm3 in the right lung and 4.25 (3.2-13.9) cm3 in the left lung. The CPAP group had 9.5 (3.1-23.7) cm3 of collapsed lung tissue in the right lung and 8.8 (5.3-28.5) cm3 in the left lung. Only one patient in the ARS group presented an atelectasis of less than 2 cm3. An uneven distribution of the atelectasis was observed within each lung and between the right and left lungs, with a clear predominance of the left basal paradiaphragmatic regions. Frequency of atelectasis was much less following the alveolar recruitment strategy, compared with children who did not have the maneuver performed. The

  12. Management of ARDS and Refractory Hypoxemia: A Multicenter Observational Study.

    PubMed

    Duan, Erick H; Adhikari, Neill Kj; D'Aragon, Frederick; Cook, Deborah J; Mehta, Sangeeta; Alhazzani, Waleed; Goligher, Ewan; Charbonney, Emmanuel; Arabi, Yaseen M; Karachi, Tim; Turgeon, Alexis F; Hand, Lori; Zhou, Qi; Austin, Peggy; Friedrich, Jan; Lamontagne, Francois; Lauzier, François; Patel, Rakesh; Muscedere, John; Hall, Richard; Aslanian, Pierre; Piraino, Thomas; Albert, Martin; Bagshaw, Sean M; Jacka, Mike; Wood, Gordon; Henderson, William; Dorscheid, Delbert; Ferguson, Niall D; Meade, Maureen O

    2017-09-14

    Clinicians' current practice patterns in the management of acute respiratory distress syndrome (ARDS) and refractory hypoxemia are not well described. To describe mechanical ventilation strategies and treatment adjuncts for adults with ARDS including refractory hypoxemia. Prospective cohort study (March 2014-February 2015) of mechanically ventilated adults with moderate-to-severe ARDS requiring FiO2 ≥0.50 in 24 ICUs. We enrolled 664 patients: 222 (33%) with moderate and 442 (67%) with severe ARDS. On study day 1, mean tidal volume (VT) was 7.5 (SD2.1) ml/kg predicted body weight (n=625); 79% (n=496) received VT>6 ml/kg. Mean positive end-expiratory pressure (PEEP) was 10.5 (3.7) cmH2O (n=653); 568 patients (87%) received PEEP<15 cmH2O. Treatment adjuncts were common (n=440, 66%): neuromuscular blockers (n=276, 42%), pulmonary vasodilators (n=118, 18%), prone positioning (n=67, 10%), extracorporeal life support (n=29, 4%), and high-frequency oscillatory ventilation (n=29, 4%). Refractory hypoxemia, defined as PaO2<60 mmHg on FiO2 1.0, occurred in 138 (21%) patients. At onset of refractory hypoxemia, mean VT was 7.1 (2.0) ml/kg (n=127); 32 patients (26%) received VT>8 ml/kg. Mean PEEP was 12.1 (4.4) cmH2O (n=135); 99 patients (74%) received PEEP<15 cmH2O. Among patients with refractory hypoxemia, 91% received treatment adjuncts (126/138), with increased use of neuromuscular blockers (n=96, 70%), pulmonary vasodilators (n=62, 45%), and prone positioning (n=37, 27%). Patients with moderate-to-severe ARDS, receive treatment adjuncts frequently, especially with refractory hypoxemia. Paradoxically, therapies with less evidence supporting their use (e.g. pulmonary vasodilators) were over-utilized, while those with more evidence (e.g. prone positioning, neuromuscular blockade) were under-utilized. Patients received higher tidal volumes and lower PEEP than would be suggested by the evidence.

  13. Low Tidal Volume versus Non-Volume-Limited Strategies for Patients with Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis.

    PubMed

    Walkey, Allan J; Goligher, Ewan; Del Sorbo, Lorenzo; Hodgson, Carol; Adhikari, Neill Kj; Wunsch, Hannah; Meade, Maureen O; Uleryk, Elizabeth; Hess, Dean; Talmor, Daniel S; Thompson, B Taylor; Brower, Roy G; Fan, Eddy

    2017-08-28

    Trials investigating use of lower tidal volumes and inspiratory pressures for patients with acute respiratory distress syndrome (ARDS) have shown mixed results. To compare clinical outcomes of mechanical ventilation strategies that limit tidal volumes and inspiratory pressures (LTV) to strategies with tidal volumes of 10-15 mL/kg among patients with ARDS. Systematic review and meta-analysis of clinical trials investigating LTV mechanical ventilation strategies. We used random effects models to evaluate effect of LTV on 28 day mortality, organ failure, ventilator-free days, barotrauma, oxygenation and ventilation. Our primary analysis excluded trials for which the LTV strategy was combined with the additional strategy of higher positive end-expiratory pressure (PEEP), but these trials were included in a stratified sensitivity analysis. We performed meta-regression of tidal volume gradient achieved between intervention and control groups on mortality effect estimates. We used GRADE methodology to determine the quality of evidence. Seven randomized trials involving 1481 patients met eligibility criteria for this review. Mortality was not significantly lower for patients receiving a LTV strategy (33.6%) as compared to control strategies (40.4%) [RR 0.87 (95% CI 0.70-1.08), I2 = 46%], nor did an LTV strategy significantly decrease barotrauma or ventilator-free days when compared to a lower PEEP strategy. Quality of evidence for clinical outcomes was downgraded for imprecision. Meta-regression showed a significant inverse association between larger tidal volume gradient between LTV and control groups and log odds ratios for mortality (β -0.1587, p=0.0022). Sensitivity analysis including trials that protocolized a LTV/high PEEP co-intervention showed lower mortality associated with LTV [9 trials and 1629 patients; RR 0.80, (95% CI 0.66-0.98), I2 =46%]. Compared with trials not using a high PEEP co-intervention, trials using a strategy of LTV combined with high PEEP

  14. Measurement of tidal volume using respiratory ultrasonic plethysmography in anaesthetized, mechanically ventilated horses.

    PubMed

    Russold, Elena; Ambrisko, Tamas D; Schramel, Johannes P; Auer, Ulrike; Van Den Hoven, Rene; Moens, Yves P

    2013-01-01

    To compare tidal volume estimations obtained from Respiratory Ultrasonic Plethysmography (RUP) with simultaneous spirometric measurements in anaesthetized, mechanically ventilated horses. Prospective randomized experimental study. Five experimental horses. Five horses were anaesthetized twice (1 week apart) in random order in lateral and in dorsal recumbency. Nine ventilation modes (treatments) were scheduled in random order (each lasting 4 minutes) applying combinations of different tidal volumes (8, 10, 12 mL kg(-1)) and positive end-expiratory pressures (PEEP) (0, 10, 20 cm H(2)O). Baseline ventilation mode (tidal volume=15 mL kg(-1), PEEP=0 cm H(2)O) was applied for 4 minutes between all treatments. Spirometry and RUP data were downloaded to personal computers. Linear regression analyses (RUP versus spirometric tidal volume) were performed using different subsets of data. Additonally RUP was calibrated against spirometry using a regression equation for all RUP signal values (thoracic, abdominal and combined) with all data collectively and also by an individually determined best regression equation (highest R(2)) for each experiment (horse versus recumbency) separately. Agreement between methods was assessed with Bland-Altman analyses. The highest correlation of RUP and spirometric tidal volume (R(2)=0.81) was found with the combined RUP signal in horses in lateral recumbency and ventilated without PEEP. The bias ±2 SD was 0±2.66 L when RUP was calibrated for collective data, but decreased to 0±0.87 L when RUP was calibrated with individual data. A possible use of RUP for tidal volume measurement during IPPV needs individual calibration to obtain limits of agreement within ±20%. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

  15. Particle Size Concentration Distribution and Influences on Exhaled Breath Particles in Mechanically Ventilated Patients

    PubMed Central

    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. PMID:24475230

  16. Increased flow resistance and decreased flow rate in patients with acute respiratory distress syndrome: The role of autonomic nervous modulation.

    PubMed

    Chen, I-Chen; Kuo, Jane; Ko, Wen-Je; Shih, Hsin-Chin; Kuo, Cheng-Deng

    2016-01-01

    The aim of this study was to investigate the flow resistance and flow rate in patients with acute respiratory distress syndrome (ARDS) in the surgical intensive care unit and their relation with autonomic nervous modulation. Postoperative patients of lung or esophageal cancer surgery without ARDS were included as the control group (n = 11). Patients who developed ARDS after lung or esophageal cancer surgery were included as the ARDS group (n = 21). The ARDS patients were further divided into survivor and nonsurvivor subgroups according to their outcomes. All patients required intubation and mechanical ventilation. The flow rate was significantly decreased, while the flow resistance was significantly increased, in ARDS patients. The flow rate correlated significantly and negatively with positive end-expiratory pressure (PEEP), while the flow resistance correlated significantly and positively with PEEP in ARDS patients. Furthermore, the flow rate correlated significantly and negatively with the tidal volume-corrected normalized high-frequency power but correlated significantly and positively with the tidal volume-corrected low-/high-frequency power ratio. In contrast, the flow resistance correlated significantly and negatively with normalized very low-frequency power and tidal volume-corrected low-/high-frequency power ratio, but correlated significantly and positively with tidal volume-corrected normalized high-frequency power. The flow rate is decreased and the flow resistance increased in patients with ARDS. PEEP is one of the causes of increased flow resistance and decreased flow rate in patients with ARDS. Another cause of decreased flow rate and increased flow resistance in ARDS patients is the increased vagal activity and decreased sympathetic activity. The monitoring of flow rate and flow resistance during mechanical ventilation might be useful for the proper management of ARDS patients. Copyright © 2015. Published by Elsevier Taiwan LLC.

  17. Imaging the Interaction of Atelectasis and Overdistention in Surfactant Depleted Lungs

    PubMed Central

    Cereda, Maurizio; Emami, Kiarash; Xin, Yi; Kadlecek, Stephen; Kuzma, Nicholas N.; Mongkolwisetwara, Puttisarn; Profka, Harrilla; Pickup, Stephen; Ishii, Masaru; Kavanagh, Brian P.; Deutschman, Clifford S.; Rizi, Rahim R.

    2012-01-01

    Objective Atelectasis and surfactant depletion may contribute to greater distension – and thereby injury – of aerated lung regions; recruitment of atelectatic lung may protect these regions by attenuating such overdistension. However, the effects of atelectasis (and recruitment) on aerated airspaces remain elusive. We tested the hypothesis that during mechanical ventilation, surfactant depletion increases the dimensions of aerated airspaces and that lung recruitment reverses these changes. Design Prospective imaging study in an animal model. Setting Research imaging facility Subjects 27 healthy Sprague Dawley rats Interventions Surfactant depletion was obtained by saline lavage in anesthetized, ventilated rats. Alveolar recruitment was accomplished using positive end-expiratory pressure (PEEP) and exogenous surfactant administration. Measurements and Main Results Airspace dimensions were estimated by measuring the apparent diffusion coefficient (ADC) of 3He, using diffusion-weighted hyperpolarized gas magnetic resonance imaging (MRI). Atelectasis was demonstrated using computerized tomography (CT) and by measuring oxygenation. Saline lavage increased atelectasis (increase in non-aerated tissue from 1.2 to 13.8% of imaged area, P<0.001), and produced a concomitant increase in mean ADC (~33%, P<0.001) vs. baseline; the heterogeneity of the CT signal and the variance of ADC were also increased. Application of PEEP and surfactant reduced the mean ADC (~23%, P<0.001), and its variance, in parallel to alveolar recruitment (i.e. less CT densities and heterogeneity, increased oxygenation). Conclusions Overdistension of aerated lung occurs during atelectasis, is detectable using clinically relevant MRI technology, and could be a key factor in the generation of lung injury during mechanical ventilation. Lung recruitment by higher PEEP and surfactant administration reduces airspace distension. PMID:23263577

  18. Post-operative atelectasis - a randomised trial investigating a ventilatory strategy and low oxygen fraction during recovery.

    PubMed

    Edmark, L; Auner, U; Lindbäck, J; Enlund, M; Hedenstierna, G

    2014-07-01

    Atelectasis is common during and after general anaesthesia. We hypothesized that a ventilation strategy with a combination of 1) continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) and 2) a reduced end-expiratory oxygen concentration during recovery would reduce post-operative atelectasis. Sixty patients were randomized into two groups. During anaesthesia induction, inspiratory oxygen fraction (FIO2) was 1.0, and depending on weight, CPAP 6, 7 or 8 cmH2O was applied in both groups via facemask. During maintenance of anaesthesia, a laryngeal mask airway (LMA) was used, and PEEP was 6-8 cmH2O in both groups. Before removal of the LMA, FIO2 was set to 0.3 in the intervention group and 1.0 in the control group. Atelectasis was studied by computed tomography (CT) approximately 14 min post-operatively. In one patient in the group given an FIO2 of 0.3 before removal of the LMA a CT scan could not be performed so the patient was excluded. The area of atelectasis was 5.5, 0-16.9 cm(2) (median and range), and 6.8, 0-27.5 cm(2) in the groups given FIO2 0.3 or FIO2 1.0 before removal of the LMA, a difference that was not statistically significant (P = 0.48). Post-hoc analysis showed dependence of atelectasis on smoking (despite all were clinically lung healthy) and American Society of Anesthesiologists class (P = 0.038 and 0.015, respectively). Inducing anaesthesia with CPAP/PEEP and FIO2 1.0 and deliberately reducing FIO2 during recovery before removal of the LMA did not reduce post-operative atelectasis compared with FIO2 1.0 before removal of the LMA. © 2014 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  19. The effect of hydrophilic and hydrophobic structure of amphiphilic polymeric micelles on their transport in epithelial MDCK cells.

    PubMed

    Yu, Chao; He, Bing; Xiong, Meng-Hua; Zhang, Hua; Yuan, Lan; Ma, Ling; Dai, Wen-Bing; Wang, Jun; Wang, Xing-Lin; Wang, Xue-Qing; Zhang, Qiang

    2013-08-01

    The interaction of nanocarriers with cells including their transcellular behavior is vital not only for a drug delivery system, but also for the safety of nanomaterials. In an attempt to clarify how the structures of polymers impact the transport mechanisms of their nanocarriers in epithelial cells, three amphiphilic polymers (PEEP-PCL, PEG-PCL and PEG-DSPE) with different hydrophilic or hydrophobic blocks were synthesized or chosen to form different micelle systems here. The endocytosis, exocytosis, intracellular colocalization, paracellular permeability and transcytosis of these micelle systems were compared using Förster resonance energy transfer analysis, real-time confocal images, colocalization assay, transepithelial electrical resistance study, and so on. All micelle systems were found intact during the studies with cells. The endocytosis and exocytosis studies with undifferentiated MDCK cells and the transcytosis study with differentiated MDCK monolayers all indicated the fact that PEG-DSPE micelles achieved the most and fastest transport, followed by PEG-PCL and PEEP-PCL in order. These might be because DSPE has higher hydrophobicity than PCL while PEG has lower hydrophilicity than PEEP. Different in hydrophilic or hydrophobic structures, all kinds of micelles demonstrated similar pathways during endocytosis and exocytosis, both caveolae- and clathrin-mediated but with difference in degree. The colocalization studies revealed different behaviors in intracellular trafficking among the three polymer micelles, suggesting the decisive role of hydrophilic shells on this process. Finally, all micelle systems did not impact the paracellular permeability of test cell monolayer. In conclusion, the hydrophilic and hydrophobic structures of test micelles could influence their transport ability, intracellular trafficking and the transport level under each pathway in MDCK cells. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. The Effect of Hydrophilic and Hydrophobic Structure of Amphiphilic Polymeric Micelles on Their Transportation in Rats.

    PubMed

    Deng, Feiyang; Yu, Chao; Zhang, Hua; Dai, Wenbing; He, Bing; Zheng, Ying; Wang, Xueqing; Zhang, Qiang

    2016-01-01

    In the previous study, we have clarified how the hydrophilic and hydrophobic structures of amphiphilic polymers impact the transport of their micelles (PEEP-PCL, PEG-PCL and PEG-DSPE micelles) in epithelial MDCK cells (Biomaterials 2013, 34: 6284-6298). In this study, we attempt to clarify the behavior of the three micelles in rats. Coumarin-6 loaded micelles were injected into different sections of intestine of rats and observed by confocal laser scanning microscope (CLSM) or orally administrated and conducted pharmacokinetic study. All of the three kinds of micelles were able to cross the intestinal epithelial cells and enter blood circulation. The PEEP-PCL micelles demonstrated the fastest distribution mainly in duodenum, while the PEGDSPE micelles showed the longest distribution with the highest proportion in ileum of the three. No significant difference was observed among the pharmacokinetic parameters of the three micelles. The results were consistent in the two analysis methods mentioned above, yet there were some differences between in vivo and in vitro results reported previously. It might be the distinction between the environments in MDCK model and intestine that led to the discrepancy. The hydrophobicity of nanoparticles could both enhance uptake and hinder the transport across the mucus. However, there was no intact mucus in MDCK model, which preferred hydrophobic nanoparticles. PEEP was the most hydrophilic material constructing the micelles in the study and its uptake would be increased in rats compared to that in MDCK model, while DSPE was more hydrophobic than the others and MDCK model would be more ideal for its uptake. Considering the inconsistency of the results in the two models, whether the methods researchers were generally using at present were reasonable needs further investigation.

  1. Regional intratidal gas distribution in acute lung injury and acute respiratory distress syndrome assessed by electric impedance tomography.

    PubMed

    Lowhagen, K; Lundin, S; Stenqvist, O

    2010-12-01

    Regional tidal volume distribution and end-expiratory lung volume (EELV) distribution in patients with acute lung injury and acute respiratory distress syndrome (ALI, ARDS) have previously been investigated using computed tomograpy and electric impedance tomography (EIT). In the present study, we utilized the high temporal resolution of EIT to assess intratidal gas distribution. Sixteen ventilator patients with ALI/ARDS were studied. EIT was used for analysis of intertidal, intratidal and EELV regional distribution. Intratidal regional gas distribution (ITV) was analyzed by dividing the regional tidal impedance signal into eight iso-volume parts. Alveolar pressure/volume curves during ongoing ventilation and volume-dependent compliance during the initial inspiration (Cini) were calculated. A low-pressure (~32 cm H2O) recruitment maneuver and a decremental PEEPtrial were implemented. The increase in EELV was preferentially distributed to non-dependent lung regions. The intratidal gas distribution pattern was similar to the tidal volume distribution following increased PEEP; non-dependent distribution decreased and dependent distribution increased during inspiration. Cini increased, indicating successful recruitment. The distribution varied widely among individual patients. In one patient with a low EELV, the ITV pattern showed that non-dependent distribution increased and dependent distribution decreased. This coincided with minimal improvement in volume-dependent compliance. This patient probably needed higher recruitment pressure. In one patient with a high baseline EELV, there was very little change in regional ITV, and non-dependent Cini decreased. This was probably a patient with low potential recruitability, who required only moderate PEEP. On-line intratidal gas distribution monitoring offers additional information on recruitability and optimal PEEP.

  2. Respiratory Management of Perioperative Obese Patients.

    PubMed

    Imber, David Ae; Pirrone, Massimiliano; Zhang, Changsheng; Fisher, Daniel F; Kacmarek, Robert M; Berra, Lorenzo

    2016-12-01

    With a rising incidence of obesity in the United States, anesthesiologists are faced with a larger volume of obese patients coming to the operating room as well as obese patients with ever-larger body mass indices (BMIs). While there are many cardiovascular and endocrine issues that clinicians must take into account when caring for the obese patient, one of the most prominent concerns of the anesthesiologist in the perioperative setting should be the status of the lung. Because the pathophysiology of reduced lung volumes in the obese patient differs from that of the ARDS patient, the best approach to keeping the obese patient's lung open and adequately ventilated during mechanical ventilation is unique. Although strong evidence and research are lacking regarding how to best ventilate the obese surgical patient, we aim with this review to provide an assessment of the small amount of research that has been conducted and the pathophysiology we believe influences the apparent results. We will provide a basic overview of the anatomy and pathophysiology of the obese respiratory system and review studies concerning pre-, intra-, and postoperative respiratory care. Our focus in this review centers on the best approach to keeping the lung recruited through the prevention of compression atelectasis and the maintaining of physiological lung volumes. We recommend the use of PEEP via noninvasive ventilation (NIV) before induction and endotracheal intubation, the use of both PEEP and periodic recruitment maneuvers during mechanical ventilation, and the use of PEEP via NIV after extubation. It is our hope that by studying the underlying mechanisms that make ventilating obese patients so difficult, future research can be better tailored to address this increasingly important challenge to the field of anesthesia. Copyright © 2016 by Daedalus Enterprises.

  3. A Meta-analysis of Intraoperative Ventilation Strategies to Prevent Pulmonary Complications: Is Low Tidal Volume Alone Sufficient to Protect Healthy Lungs?

    PubMed

    Yang, Dongjie; Grant, Michael C; Stone, Alexander; Wu, Christopher L; Wick, Elizabeth C

    2016-05-01

    The clinical benefits of intraoperative low tidal volume (LTV) mechanical ventilation with concomittent positive end expiratory pressure (PEEP) and intermittent recruitment maneuvers-termed "protective lung ventilation" (PLV)-have not been investigated systematically in otherwise healthy patients undergoing general anesthesia. Our group performed a meta-analysis of 16 studies (n = 1054) comparing LTV (n = 521) with conventional lung ventilation (n = 533) for associated postoperative incidence of atelectasis, lung infection, acute lung injury (ALI), and length of hospital stay. A secondary analysis of 3 studies comparing PLV (n = 248) with conventional lung ventilation (n = 247) was performed. Although intraoperative LTV ventilation was associated with a decreased incidence of postoperative lung infection (odds ratio [OR] = 0.33; 95% confidence interval [CI], 0.16-0.68; P = 0.003) compared with a conventional strategy, no difference was noted between groups in incidence of postoperative ALI (OR = 0.38; 95% CI, 0.10-1.52; P = 0.17) or atelectasis (OR = 0.86; 95% CI, 0.26-2.81; P = 0.80). Analysis of trials involving protective ventilation (LTV + PEEP + recruitment maneuvers) showed a statistically significant reduction in incidence of postoperative lung infection (OR = 0.21; 95% CI, 0.09-0.50; P = 0.0003), atelectasis (OR = 0.36; 95% CI, 0.20-0.64; P = 0.006), and ALI (OR = 0.15; 95% CI, 0.04-0.61; P = 0.008) and length of hospital stay (Mean Difference = -2.08; 95% CI, -3.95 to -0.21; P = 0.03) compared with conventional ventilation. Intraoperative LTV ventilation in conjunction with PEEP and intermittent recruitment maneuvers is associated with significantly improved clinical pulmonary outcomes and reduction in length of hospital stay in otherwise healthy patients undergoing general surgery. Providers should consider application of all the 3 elements for a comprehensive protective ventilation strategy.

  4. Alveolar recruitment maneuvers under general anesthesia: a systematic review of the literature.

    PubMed

    Hartland, Benjamin L; Newell, Timothy J; Damico, Nicole

    2015-04-01

    The sigh is a normal homeostatic reflex that maintains lung compliance and decreases atelectasis. General anesthesia abolishes the sigh reflex with rapid onset of atelectasis in 100% of patients. Studies show a strong correlation between atelectasis and postoperative pulmonary complications, raising health-care costs. Alveolar recruitment maneuvers recruit collapsed alveoli, increase gas exchange, and improve arterial oxygenation. There is no consensus in the literature about the benefits of alveolar recruitment maneuvers. A systematic review is necessary to delineate their usefulness. The search strategy included utilizing PubMed, CINAHL, the Cochrane Library, the National Guideline Clearinghouse, and all subsequent research reference lists up to January 2014. Inclusion criteria involved studies that compared the use of an alveolar recruitment maneuver with a control group lacking an alveolar recruitment maneuver in adult surgical subjects not suffering from ARDS or undergoing cardiac or thoracic surgeries. Six randomized controlled trials of the 439 studies initially identified achieved a score of ≥ 3 on the Jadad scale and were included in this review. Alveolar recruitment maneuvers consisted of a stepwise increase in tidal volume to a plateau pressure of 30 cm H2O, a stepwise increase in PEEP to 20 cm H2O, or sustained manual inflations of the anesthesia reservoir bag to a peak inspiratory pressure of 40 cm H2O. Subjects in the alveolar recruitment maneuver groups experienced a higher intraoperative PaO2 with improved lung compliance. Different alveolar recruitment maneuvers were equally effective. There was a significant advantage when alveolar recruitment maneuvers were followed by PEEP application. Alveolar recruitment maneuvers followed by PEEP should be instituted after induction of general anesthesia, routinely during maintenance, and in the presence of a falling SpO2 whenever feasible. They allow the anesthesia provider to reduce the FIO2 while

  5. Ventilator setting in ICUs: comparing a Dutch with a European cohort.

    PubMed

    van IJzendoorn, M C O; Koopmans, M; Strauch, U; Heines, S; den Boer, S; Kors, B M; van der Voort, P H J; Dennesen, P J W; van den Hul, I; Alberts, E; Egbers, P; Esteban, A; Frutos-Vivar, F; Kuiper, M A

    2014-11-01

    From data collected during the third International Study on Mechanical Ventilation (ISMV), we compared data from a Dutch cohort with a European cohort. We hypothesised that tidal volumes were smaller and applied positive end-expiratory pressure (PEEP) was higher in the Netherlands, compared with the European cohort. We also compared use of non-invasive ventilation (NIV) and outcomes in both cohorts. A post-hoc analysis of a prospective observational study of patients receiving mechanical ventilation. Tidal volumes were smaller (7.6 vs. 8.1 ml÷kg predicted bodyweight) in the Dutch cohort and applied PEEP was higher (8 vs. 6 cm H2O). Fewer patients admitted in the Netherlands received NIV as first mode of mechanical ventilation (7.1 vs. 16.7%). Fewer patients in the Dutch cohort developed an ICU-acquired pneumonia (4.5 vs. 12.3%, p < 0.01) and sepsis (5.7 vs. 10.9%, p = 0.03), but more patients were diagnosed as having delirium (15.8 vs. 4.6%, p < 0.01). ICU and in-hospital mortality rates were 19% and 25%, respectively, in Dutch ICUs vs. 26% and 33% in Europe (p = 0.06 and 0.03). Tidal volumes were smaller and applied PEEP was higher in the Dutch cohort compared with international data, but both Dutch and international patients received larger tidal volumes than recommended for prevention or treatment of acute respiratory distress syndrome. NIV as first mode of mechanical ventilation is less commonly used in the Netherlands. The incidence of ICU-acquired pneumonia is lower and of delirium higher in the Netherlands compared with international data.

  6. Pneumoperitoneum deteriorates intratidal respiratory system mechanics: an observational study in lung-healthy patients.

    PubMed

    Wirth, Steffen; Biesemann, Andreas; Spaeth, Johannes; Schumann, Stefan

    2017-02-01

    Pneumoperitoneum during laparoscopic surgery leads to atelectasis and impairment of oxygenation. Positive end-expiratory pressure (PEEP) is supposed to counteract atelectasis. We hypothesized that the derecruiting effects of pneumoperitoneum would deteriorate the intratidal compliance profile in patients undergoing laparoscopic surgery. In 30 adult patients scheduled for surgery with pneumoperitoneum, respiratory variables were measured during mechanical ventilation. We calculated the dynamic compliance of the respiratory system (C RS) and the intratidal volume-dependent C RS curve using the gliding-SLICE method. The C RS curve was then classified in terms of indicating intratidal recruitment/derecruitment (increasing profile) and overdistension (decreasing profile). During the surgical interventions, the PEEP level was maintained nearly constant at 7 cm H2O. Data are expressed as mean [confidence interval]. Baseline C RS was 60 [54-67] mL cm H2O(-1). Application of pneumoperitoneum decreased C RS to 40 [37-43] mL cm H2O(-1) which partially recovered to 54 [50-59] mL cm H2O(-1) (P < 0.001) after removal but remained below the value measured before pneumoperitoneum (P < 0.001). Baseline compliance profiles indicated intratidal recruitment/derecruitment in 48 % patients. After induction of pneumoperitoneum, intratidal recruitment/derecruitment was indicated in 93 % patients (P < 0.01), and after removal intratidal recruitment/derecruitment was indicated in 59 % patients. Compliance profiles showing overdistension were not observed. Analyses of the intratidal compliance profiles reveal that pneumoperitoneum during laparoscopic surgery causes intratidal recruitment/derecruitment which partly persists after its removal. The analysis of the intratidal volume-dependent C RS profiles could be used to guide intraoperative PEEP adjustments during elevated intraabdominal pressure.

  7. Combination of constant-flow and continuous positive-pressure ventilation in canine pulmonary edema.

    PubMed

    Sznajder, J I; Becker, C J; Crawford, G P; Wood, L D

    1989-08-01

    Constant-flow ventilation (CFV) maintains alveolar ventilation without tidal excursion in dogs with normal lungs, but this ventilatory mode requires high CFV and bronchoscopic guidance for effective subcarinal placement of two inflow catheters. We designed a circuit that combines CFV with continuous positive-pressure ventilation (CPPV; CFV-CPPV), which negates the need for bronchoscopic positioning of CFV cannula, and tested this system in seven dogs having oleic acid-induced pulmonary edema. Addition of positive end-expiratory pressure (PEEP, 10 cmH2O) reduced venous admixture from 44 +/- 17 to 10.4 +/- 5.4% and kept arterial CO2 tension (PaCO2) normal. With the innovative CFV-CPPV circuit at the same PEEP and respiratory rate (RR), we were able to reduce tidal volume (VT) from 437 +/- 28 to 184 +/- 18 ml (P less than 0.001) and elastic end-inspiratory pressures (PEI) from 25.6 +/- 4.6 to 17.7 +/- 2.8 cmH2O (P less than 0.001) without adverse effects on cardiac output or pulmonary exchange of O2 or CO2; indeed, PaCO2 remained at 35 +/- 4 Torr even though CFV was delivered above the carina and at lower (1.6 l.kg-1.min-1) flows than usually required to maintain eucapnia during CFV alone. At the same PEEP and RR, reduction of VT in the CPPV mode without CFV resulted in CO2 retention (PaCO2 59 +/- 8 Torr). We conclude that CFV-CPPV allows CFV to effectively mix alveolar and dead spaces by a small bulk flow bypassing the zone of increased resistance to gas mixing, thereby allowing reduction of the CFV rate, VT, and PEI for adequate gas exchange.

  8. Ventilator waveforms.

    PubMed

    Mellema, Matthew S

    2013-08-01

    Ventilator waveforms are graphic representations of changes in pressure, flow, and volume within a ventilator circuit. The changes in these parameters over time may be displayed individually (scalars) or plotted one against another (pressure-volume and flow-volume loops). There are 6 basic shapes of scalar waveforms, but only 3 are functionally distinct (square, ramp, and sine). The pressure scalar is a particularly valuable tool when constant flow (e.g., volume control) modes are employed and an inspiratory pause is added. In this setting, inspection of the pressure waveform can allow determination of static, quasistatic, and dynamic compliance, as well as relative changes in airway resistance. Inspection of the pressure waveform can also help to identify many important aspects of patient drug responses, dyssynchrony, and air trapping (auto positive end-expiratory pressure [auto-PEEP]). Depending on the ventilation mode employed, the shape of the flow waveform may be set by the ventilator operator or may be dependent on patient effort and lung mechanics. Decelerating flow patterns have several important advantages when this option is available. Inspection of flow waveforms is crucial in the recognition of dyssynchrony, setting optimal inspiratory times, evaluating responses to bronchodilators, and the recognition of auto-PEEP. The volume waveform often contains somewhat less useful information than the other 2 scalars, but plays a crucial role in the identification of leaks in the circuit. Pressure-volume loops are particularly useful in setting PEEP and peak inspiratory pressure ranges. Inspection of these loops also often helps in the evaluation of lung mechanics, in the identification of circuit leaks, and in the assessment of patient triggering effort. Flow-volume loops are extremely useful in the identification of leaks and excessive airway secretions as well as alterations in airway resistance. Lastly, serial waveform inspection is crucial to the

  9. Intratidal Overdistention and Derecruitment in the Injured Lung: A Simulation Study.

    PubMed

    Amini, Reza; Herrmann, Jacob; Kaczka, David W

    2017-03-01

    Ventilated patients with the acute respiratory distress syndrome (ARDS) are predisposed to cyclic parenchymal overdistention and derecruitment, which may worsen existing injury. We hypothesized that intratidal variations in global mechanics, as assessed at the airway opening, would reflect such distributed processes. We developed a computational lung model for determining local instantaneous pressure distributions and mechanical impedances continuously during a breath. Based on these distributions and previous literature, we simulated the within-breath variability of airway segment dimensions, parenchymal viscoelasticity, and acinar recruitment in an injured canine lung for tidal volumes( VT ) of 10, 15, and 20 mL·kg(-1) and positive end-expiratory pressures (PEEP) of 5, 10, and 15 cm H2O. Acini were allowed to transition between recruited and derecruited states when exposed to stochastically determined critical opening and closing pressures, respectively. For conditions of low VT and low PEEP, we observed small intratidal variations in global resistance and elastance, with a small number of cyclically recruited acini. However, with higher VT and PEEP, larger variations in resistance and elastance were observed, and the majority of acini remained open throughout the breath. Changes in intratidal resistance, elastance, and impedance followed well-defined parabolic trajectories with tracheal pressure, achieving minima near 12 to 16 cm H2O. Intratidal variations in lung mechanics may allow for optimization of ventilator settings in patients with ARDS, by balancing lung recruitment against parenchymal overdistention. Titration of airway pressures based on variations in intratidal mechanics may mitigate processes associated with injurious ventilation.

  10. Expiratory model-based method to monitor ARDS disease state

    PubMed Central

    2013-01-01

    Introduction Model-based methods can be used to characterise patient-specific condition and response to mechanical ventilation (MV) during treatment for acute respiratory distress syndrome (ARDS). Conventional metrics of respiratory mechanics are based on inspiration only, neglecting data from the expiration cycle. However, it is hypothesised that expiratory data can be used to determine an alternative metric, offering another means to track patient condition and guide positive end expiratory pressure (PEEP) selection. Methods Three fully sedated, oleic acid induced ARDS piglets underwent three experimental phases. Phase 1 was a healthy state recruitment manoeuvre. Phase 2 was a progression from a healthy state to an oleic acid induced ARDS state. Phase 3 was an ARDS state recruitment manoeuvre. The expiratory time-constant model parameter was determined for every breathing cycle for each subject. Trends were compared to estimates of lung elastance determined by means of an end-inspiratory pause method and an integral-based method. All experimental procedures, protocols and the use of data in this study were reviewed and approved by the Ethics Committee of the University of Liege Medical Faculty. Results The overall median absolute percentage fitting error for the expiratory time-constant model across all three phases was less than 10 %; for each subject, indicating the capability of the model to capture the mechanics of breathing during expiration. Provided the respiratory resistance was constant, the model was able to adequately identify trends and fundamental changes in respiratory mechanics. Conclusion Overall, this is a proof of concept study that shows the potential of continuous monitoring of respiratory mechanics in clinical practice. Respiratory system mechanics vary with disease state development and in response to MV settings. Therefore, titrating PEEP to minimal elastance theoretically results in optimal PEEP selection. Trends matched clinical

  11. Implementation of a minimal set of biological tests to assess the ecotoxic effects of effluents from land-based marine fish farms.

    PubMed

    Carballeira, C; De Orte, M R; Viana, I G; Carballeira, A

    2012-04-01

    Environmental monitoring plans (EMP) that include chemical analysis of water, a battery of bioassays and the study of local hydrodynamic conditions are required for land-based marine aquaculture. In this study, the following standardized toxicity tests were performed to assess the toxicity of effluents from eight land-base marine fish farms (LBMFFs) located on the northwest coast of Spain: bacterial bioluminescence (with Vibrio fischeri at 15 and 30 min), microalgal growth (with Phaeodactyllum tricornutum and Isochrysis galbana) and sea urchin larval development (with Paracentrotus lividus and Arbacia lixula). These bioassays were evaluated for inclusion in routine fish farm monitoring. Effective concentrations (EC(5), EC(10), EC(20), EC(50)) for each bioassay were calculated from dose-response curves, obtained by fitting the bioassay results to the best parametric model. Moreover, a graphical method of integrating the results from the battery of bioassays and classifying the toxicity was proposed, and the potential ecotoxic effects probe (PEEP) index was calculated. The bacterial bioluminiscence test at 30min, growth of I. galbana and larval development of A. lixula were found to be the most sensitive and useful tests. Graphical integration of these test results enabled definition of the ecotoxicological profiles of the different farms. The PEEP index, considering EC(20), efficiently reflected the toxic loading potential of LBMFF effluents. In conclusion, a battery of bioassays with species from different low trophic levels is recommended as a rapid and cost-effective methodology for assessing LBMFF discharges. The graphical integration method and the PEEP index are proposed for consideration in EMPs for such farms.

  12. Mechanical ventilation modulates Toll-like receptor signaling pathway in a sepsis-induced lung injury model.

    PubMed

    Villar, Jesús; Cabrera, Nuria; Casula, Milena; Flores, Carlos; Valladares, Francisco; Muros, Mercedes; Blanch, Lluis; Slutsky, Arthur S; Kacmarek, Robert M

    2010-06-01

    Experimental and clinical studies on sepsis have demonstrated activation of the innate immune response following the initial host-bacterial interaction. In addition, mechanical ventilation (MV) can induce a pulmonary inflammatory response. How these two responses interact when present simultaneously remains to be elucidated. We hypothesized that MV modulates innate host response during sepsis by influencing Toll-like receptor (TLR) signaling. Prospective, randomized, controlled animal study. Male, septic Sprague-Dawley rats. Sepsis was induced by cecal ligation and perforation. At 18 h, surviving animals had the cecum removed and were randomized to spontaneous breathing or two strategies of MV for 4 h: high (20 ml/kg) tidal volume (V (T)) with no positive end-expiratory pressure (PEEP) versus low V (T) (6 ml/kg) plus 10 cmH(2)O PEEP. Histological evaluation, TLR-2, TLR-4, inhibitory kappaB alpha (IkappaBalpha), interleukin-1 receptor-associated kinase-3 (IRAK-3) gene expression, protein levels and immunohistochemical lung localization, inflammatory cytokines gene expression, and protein serum concentrations were analyzed. MV with low V (T) plus PEEP attenuated sepsis-associated TLR-4 activation, and produced a significant decrease of IRAK-3 gene expression and protein levels, a significant increase of IkappaBalpha, and a decrease in lung gene expression and serum levels of cytokines. High-V (T) MV caused a significant increase of TLR-4 and IRAK-3 protein levels, lung and systemic cytokines, and mortality, and a significant decrease of IkappaBalpha. Our findings suggest a novel mechanism that could partially explain how MV modulates the innate immune response in the lung by interfering with cellular signaling pathways that are activated in response to pathogens.

  13. [Mechanical ventilatory parameters guided by the low flow pressure-volume curve in patients with acute lung injury/acute respiratory distress syndrome].

    PubMed

    Tomicic, Vinko; Molina, Jorge; Graf, Jerónimo; Espinoza, Mauricio; Antúnez, Miguel; Errázuriz, Isabel; Aguilera, Pablo; Izquierdo, Francisco; López, Tania; Canals, Claudio

    2007-03-01

    Mechanical ventilation may contribute to lung injury and then enhance systemic inflammation. Optimal ventilatory parameters such as tidal volume (VT) and positive end expiratory pressure (PEEP) can be determined using different methods. Low flow pressure volume (P/V-LF) curve is a useful tool to assess the respiratory system mechanics and set ventilatory parameters. To set VT and PEEP according P/V-LF curve analysis and evaluate its effects on gas exchange and hemodynamic parameters. Twenty seven patients underwent P/V-LF within the first 72 hours of acute lung injury/acute respiratory distress syndrome (ALI/ARDS). P/V-LF curves were obtained from the ventilator and both lower and upper inflexion points determined. Gas exchange and hemodynamic parameters were measured before and after modifying ventilator settings guided by P/V-LF curves. Ventilatory parameters set according P/V-LF curve, led to a rise of PEEP and reduction of VT: 11.6+/-2.8 to 14.1+/-2.1 cm H2O, and 9.7+/-2.4 to 8.8+/-2.2 mL/kg (p<0.01). Arterial to inspired oxygen fraction ratio increased from 158.0+/-66 to 188.5+/-68.5 (p<0.01), and oxygenation index was reduced, 13.7+/-8.2 to 12.3+/-7.2 (p<0.05). Cardiac output and oxygen delivery index (IDO2) were not modified. Demographic data, gas exchange improvement and respiratory system mechanics showed no significant difference between patients with extra-pulmonary and pulmonary ALI/ARDS. There was no evidence of significant adverse events related with this technique. P/V-LF curves information allowed us to adjust ventilatory parameters and optimize gas exchange without detrimental effects on oxygen delivery in mechanically ventilated ALI/ARDS patients.

  14. Dissociation of consummatory and vocal components of feeding in squirrel monkeys treated with benzodiazepines and alcohol.

    PubMed

    Weerts, E M; Macey, D J; Miczek, K A

    1998-09-01

    The primary aim of the current experiments was to develop methods that engender vocalizations associated with positive social situations comprising affiliative behavior and feeding that could be quantified under controlled laboratory conditions and were sensitive to anxiolytic drugs. Classical conditioning procedures were used to elicit vocalizations during presentation of stimulus lights (i.e., CS condition) previously paired with either preferred foods (e.g., grapes, peanuts, bananas) or standard foods (e.g., monkey chow) as well as during presentation of both food types (i.e., UCS condition). When compared to the period before stimulus light presentation (i.e., Pre-CS condition), the rate, duration and number of elemental units of food-related "twitter" vocalizations were increased during the CS conditions regardless of food type. Monkeys spent significantly more time oriented toward the food box during the light stimulus that preceded preferred food than for the light stimulus that preceded standard food. However, twitter vocalizations were higher for standard food regardless of the stimulus conditions (i.e., Pre-CS, CS and UCS). Administration of the benzodiazepine full agonist chlordiazepoxide (CDP, 1-10 mg/kg), the partial agonist bretazenil (BRZ, 1-10 mg/kg), the antagonist flumazenil (FLZ, 1-10 mg/kg) and ethyl alcohol (EtOH, 0.1-1.0 g/kg) differentially altered vocalizations. Although CDP and BRZ increased feeding of standard food, twitters were reduced across stimulus conditions. CDP and BRZ did not alter other social contact calls (i.e., "peeps"). FLZ also reduced twitters without altering peeps, but did not increase feeding. In contrast, EtOH did not increase feeding or peeps, but did increase food-related twitters. These results indicate that there is a dissociation between food-related behaviors, such as food consumption and orientation towards the food source, and vocal behaviors associated with group communication during feeding.

  15. Predicting others' actions via grasp and gaze: evidence for distinct brain networks.

    PubMed

    Ramsey, Richard; Cross, Emily S; Hamilton, Antonia F de C

    2012-07-01

    During social interactions, how do we predict what other people are going to do next? One view is that we use our own motor experience to simulate and predict other people's actions. For example, when we see Sally look at a coffee cup or grasp a hammer, our own motor system provides a signal that anticipates her next action. Previous research has typically examined such gaze and grasp-based simulation processes separately, and it is not known whether similar cognitive and brain systems underpin the perception of object-directed gaze and grasp. Here we use functional magnetic resonance imaging to examine to what extent gaze- and grasp-perception rely on common or distinct brain networks. Using a 'peeping window' protocol, we controlled what an observed actor could see and grasp. The actor could peep through one window to see if an object was present and reach through a different window to grasp the object. However, the actor could not peep and grasp at the same time. We compared gaze and grasp conditions where an object was present with matched conditions where the object was absent. When participants observed another person gaze at an object, left anterior inferior parietal lobule (aIPL) and parietal operculum showed a greater response than when the object was absent. In contrast, when participants observed the actor grasp an object, premotor, posterior parietal, fusiform and middle occipital brain regions showed a greater response than when the object was absent. These results point towards a division in the neural substrates for different types of motor simulation. We suggest that left aIPL and parietal operculum are involved in a predictive process that signals a future hand interaction with an object based on another person's eye gaze, whereas a broader set of brain areas, including parts of the action observation network, are engaged during observation of an ongoing object-directed hand action.

  16. 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

  17. Reliability of transpulmonary pressure-time curve profile to identify tidal recruitment/hyperinflation in experimental unilateral pleural effusion.

    PubMed

    Formenti, P; Umbrello, M; Graf, J; Adams, A B; Dries, D J; Marini, J J

    2016-07-20

    The stress index (SI) is a parameter that characterizes the shape of the airway pressure-time profile (P/t). It indicates the slope progression of the curve, reflecting both lung and chest wall properties. The presence of pleural effusion alters the mechanical properties of the respiratory system decreasing transpulmonary pressure (Ptp). We investigated whether the SI computed using Ptp tracing would provide reliable insight into tidal recruitment/overdistention during the tidal cycle in the presence of unilateral effusion. Unilateral pleural effusion was simulated in anesthetized, mechanically ventilated pigs. Respiratory system mechanics and thoracic computed tomography (CT) were studied to assess P/t curve shape and changes in global lung aeration. SI derived from airway pressure (Paw) was compared with that calculated by Ptp under the same conditions. These results were themselves compared with quantitative CT analysis as a gold standard for tidal recruitment/hyperinflation. Despite marked changes in tidal recruitment, mean values of SI computed either from Paw or Ptp were remarkably insensitive to variations of PEEP or condition. After the instillation of effusion, SI indicates a preponderant over-distension effect, not detected by CT. After the increment in PEEP level, the extent of CT-determined tidal recruitment suggest a huge recruitment effect of PEEP as reflected by lung compliance. Both SI in this case were unaffected. We showed that the ability of SI to predict tidal recruitment and overdistension was significantly reduced in a model of altered chest wall-lung relationship, even if the parameter was computed from the Ptp curve profile.

  18. Lung recruitment and positive airway pressure before extubation does not improve oxygenation in the post-anaesthesia care unit: a randomized clinical trial.

    PubMed

    Lumb, A B; Greenhill, S J; Simpson, M P; Stewart, J

    2010-05-01

    Atelectasis is known to develop during anaesthesia and after operation atelectasis leads to impaired oxygenation. Lung recruitment manoeuvres, positive end-expiratory pressure (PEEP), and continuous positive airway pressure (CPAP) have been proposed for reduction of atelectasis but their benefits have not been shown to persist after operation. We proposed that a combination of these techniques before extubation would improve oxygenation after operation. Adult patients undergoing elective surgery requiring tracheal intubation and an arterial catheter were randomized to receive either: a lung recruitment manoeuvre of 40 cm H(2)O for 15 s, 30 min before the end of anaesthesia, followed by 10 cm H(2)O of PEEP and then 10 cm H(2)O of CPAP from return of spontaneous breathing until extubation; or no lung recruitment manoeuvre, PEEP, and no CPAP. Arterial blood gases were taken at randomization and 1 h after extubation. The primary endpoint of the study was the change in (a-a)DO(2) between these times. Statistical analysis of the two groups was done by chi(2) or unpaired t-test as appropriate. Twenty-two patients were recruited to each group. There were no significant differences between the groups before randomization. There was no significant difference in the change in (a-a)DO(2) between the groups (P=0.82). Postoperative oxygenation is not improved by a combination of a lung recruitment manoeuvre and maintenance of a positive airway pressure until extubation. Further research is needed to elucidate the mechanism of atelectasis on emergence from anaesthesia and to evaluate more invasive clinical strategies such as post-extubation CPAP. Trial registered at URL http://www.controlled-trials.com Identification number: ISRCTN32464251 (http://www.controlled-trials.com/ISRCTN32464251).

  19. The optical characteristics of aiming scopes in archery.

    PubMed

    Long, W F; Haywood, K M

    1990-10-01

    Technical advancements in target archery have been extended to widespread use of "scopes" which magnify the target. In fact, these optical devices are simple converging lenses used at an arm's length from the eye. They produce a magnified image, but it is an image that suffers from significant dioptric blur, diminished somewhat by use of a peep sight in the bowstring which functions as an aperture stop. Visual acuities were taken with these scopes and, as might be expected, it was found that subjects saw no better with them. With the highest power scopes, acuity actually decreased. Experienced archers did slightly better with these aids than those with no archery experience.

  20. Development and Enhancement of a Model of Performance and Decision Making Under Stress in a Real Life Setting.

    DTIC Science & Technology

    1991-07-30

    A 1l Acute cervical spine injury A12 Management difficult airway A13 Strategies for failed intubation A14 PublicatiOns 1) Abstract titled "Decision...Ches -a AB 19 Verily tube position Chest Physiotherapy Needle/Tub.a and/or Thoracostomy Bronchoscopy PEEP Titration < F1025 0.50YesEn Control...Spinal Cord Injury < etlSau?>Deicit? Ys1 Protocol Airway Intact Esablish Airway Ventilation OK? No -0 Ventilate j yees ~ ~ lf:~OO Hypotension Yes .0 Shock

  1. Development and Evaluation of New Products for the Far-Forward Care of Combat Casualties with Acute Lung Injury

    DTIC Science & Technology

    2006-02-01

    HYPOTHESIS: IMO will improve the PaO2 -to- FiO2 (PFR) ratio in injured sheep. METHODS: Thirteen ewes (sham + IMO, n=1; injury + IMO, n=7; injury without IMO, n...arterial blood ( PaO2 ) > 60 mm Hg. At least two hours before MIGET sampling, the FiO2 was decreased to 21%. PEEP was not modified. The target for...SaO2 > 90% and PaO2 > 60 mm Hg. At baseline, the FiO2 was set at 21%, and it was adjusted as needed to maintain these goals. In general, an effort

  2. Respiratory mechanics in infants with severe bronchiolitis on controlled mechanical ventilation.

    PubMed

    Cruces, Pablo; González-Dambrauskas, Sebastián; Quilodrán, Julio; Valenzuela, Jorge; Martínez, Javier; Rivero, Natalia; Arias, Pablo; Díaz, Franco

    2017-10-06

    Analysis of respiratory mechanics during mechanical ventilation (MV) is able to estimate resistive, elastic and inertial components of the working pressure of the respiratory system. Our aim was to discriminate the components of the working pressure of the respiratory system in infants on MV with severe bronchiolitis admitted to two PICU's. Infants younger than 1 year old with acute respiratory failure caused by severe bronchiolitis underwent neuromuscular blockade, tracheal intubation and volume controlled MV. Shortly after intubation studies of pulmonary mechanics were performed using inspiratory and expiratory breath hold. The maximum inspiratory and expiratory flow (QI and QE) as well as peak inspiratory (PIP), plateau (PPL) and total expiratory pressures (tPEEP) were measured. Inspiratory and expiratory resistances (RawI and RawE) and Time Constants (KTI and KTE) were calculated. We included 16 patients, of median age 2.5 (1-5.8) months. Bronchiolitis due to respiratory syncytial virus was the main etiology (93.8%) and 31.3% had comorbidities. Measured respiratory pressures were PIP 29 (26-31), PPL 24 (20-26), tPEEP 9 [8-11] cmH2O. Elastic component of the working pressure was significantly higher than resistive and both higher than threshold (tPEEP - PEEP) (P < 0.01). QI was significantly lower than QE [5 (4.27-6.75) v/s 16.5 (12-23.8) L/min. RawI and RawE were 38.8 (32-53) and 40.5 (22-55) cmH2O/L/s; KTI and KTE [0.18 (0.12-0.30) v/s 0.18 (0.13-0.22) s], and KTI:KTE ratio was 1:1.04 (1:0.59-1.42). Analysis of respiratory mechanics of infants with severe bronchiolitis receiving MV shows that the elastic component of the working pressure of the respiratory system is the most important. The elastic and resistive components in conjunction with flow profile are characteristic of restrictive diseases. A better understanding of lung mechanics in this group of patients may lead to change the traditional ventilatory approach to severe bronchiolitis.

  3. Effects of different respiratory maneuvers on esophageal sphincters in obese patients before and during anesthesia.

    PubMed

    de Leon, A; Thörn, S-E; Raoof, M; Ottosson, J; Wattwil, M

    2010-11-01

    Data on esophageal sphincters in obese individuals during anesthesia are sparse. The aim of the present study was to evaluate the effects of different respiratory maneuvers on the pressures in the esophagus and esophageal sphincters before and during anesthesia in obese patients. Seventeen patients, aged 28-68 years, with a BMI ≥ 35 kg/m², who were undergoing a laparoscopic gastric by-pass surgery, were studied, and pressures from the hypopharynx to the stomach were recorded using high-resolution solid-state manometry. Before anesthesia, recordings were performed during normal spontaneous breathing, Valsalva and forced inspiration. The effects of anesthesia induction with remifentanil and propofol were evaluated, and positive end-expiratory pressure (PEEP) 10 cmH₂O was applied during anesthesia. During spontaneous breathing, the lower esophageal sphincter (LES) pressure was significantly lower during end-expiration compared with end-inspiration (28.5 ± 7.7 vs. 35.4 ± 10.8 mmHg, P<0.01), but barrier pressure (BrP) and intra-gastric pressure (IGP) were unchanged. LES, BrP (P<0.05) and IGP (P<0.01) decreased significantly during anesthesia. BrP remained positive in all patients. IGP increased during Valsalva (P<0.01) but was unaffected by PEEP. Esophageal pressures were positive during both spontaneous breathing and mechanical ventilation. Esophageal pressures increased during PEEP from 9.4 ± 3.8 to 11.3 ± 3.3 mmHg (P<0.01). During spontaneous breathing, the LES pressure was the lowest during end-expiration but there were no differences in BrP and IGP. LES, BrP and IGP decreased during anesthesia but BrP remained positive in all patients. During the application of PEEP, esophageal pressures increased and this may have a protective effect against regurgitation. © 2010 The Authors. Journal compilation © 2010 The Acta Anaesthesiologica Scandinavica Foundation.

  4. [An analysis of using the graphic monitoring of ventilation for an optimal choice of respiratory management parameters in patients with acute respiratory distress syndrome].

    PubMed

    Gritsan, A I; Kolesnichenko, A P; Skorobogatov, A Iu; Gritsan, G V

    2004-01-01

    The potentialities of graphic ventilation monitoring (graphic monitor "Servo Screen 390", Siemens Elema, Sweden) were analyzed for optimizing the respiratory management parameters in 48 obstetric and gynecology patients with acute respiratory distress syndrome (ARDS). The ventilation loops and curves, ALV parameters, mechanical lung properties, gas blood composition and gas indices were dynamically evaluated during examination stages. The graphic ventilation monitoring, when used for respiratory management in patients with ARDS, provides for optimizing, in the real time mode, the PEEP and Vt levels, which is in line with the AVL "safety" concept.

  5. Lung Recruitment Assessed by Respiratory Mechanics and Computed Tomography in Patients with Acute Respiratory Distress Syndrome. What Is the Relationship?

    PubMed

    Chiumello, Davide; Marino, Antonella; Brioni, Matteo; Cigada, Irene; Menga, Federica; Colombo, Andrea; Crimella, Francesco; Algieri, Ilaria; Cressoni, Massimo; Carlesso, Eleonora; Gattinoni, Luciano

    2016-06-01

    The assessment of lung recruitability in patients with acute respiratory distress syndrome (ARDS) may be important for planning recruitment maneuvers and setting positive end-expiratory pressure (PEEP). To determine whether lung recruitment measured by respiratory mechanics is comparable with lung recruitment measured by computed tomography (CT). In 22 patients with ARDS, lung recruitment was assessed at 5 and 15 cm H2O PEEP by using respiratory mechanics-based methods: (1) increase in gas volume between two pressure-volume curves (P-Vrs curve); (2) increase in gas volume measured and predicted on the basis of expected end-expiratory lung volume and static compliance of the respiratory system (EELV-Cst,rs); as well as by CT scan: (3) decrease in noninflated lung tissue (CT [not inflated]); and (4) decrease in noninflated and poorly inflated tissue (CT [not + poorly inflated]). The P-Vrs curve recruitment was significantly higher than EELV-Cst,rs recruitment (423 ± 223 ml vs. 315 ± 201 ml; P < 0.001), but these measures were significantly related to each other (R(2) = 0.93; P < 0.001). CT (not inflated) recruitment was 77 ± 86 g and CT (not + poorly inflated) was 80 ± 67 g (P = 0.856), and these measures were also significantly related to each other (R(2) = 0.20; P = 0.04). Recruitment measured by respiratory mechanics was 54 ± 28% (P-Vrs curve) and 39 ± 25% (EELV-Cst,rs) of the gas volume at 5 cm H2O PEEP. Recruitment measured by CT scan was 5 ± 5% (CT [not inflated]) and 6 ± 6% (CT [not + poorly inflated]) of lung tissue. Respiratory mechanics and CT measure-under the same term, "recruitment"-two different entities. The respiratory mechanics-based methods include gas entering in already open pulmonary units that improve their mechanical properties at higher PEEP. Consequently, they can be used to assess the overall improvement of inflation. The CT scan measures the amount of collapsed

  6. Atrax robustus envenomation.

    PubMed

    Fisher, M M; Carr, G A; McGuinness, R; Warden, J C

    1980-11-01

    Two patients who developed massive pulmonary oedema, profound vasoconstriction and hypertension followed by hypotension after Atrax Robustus envenomation are described. The pulmonary oedema is due to increased pulmonary capillary membrane permeability which may be due to neurogenic or toxic causes. Use of artificial ventilation with high level PEEP, isoprenaline and high dose steroids allowed support of the patients during volume replacement with albumin. When the circulation was stable and airway frothing ceased, conventional dehydration therapy further improved lung function. Both patients were discharged well.

  7. Analysis of atelectasis, ventilated, and hyperinflated lung during mechanical ventilation by dynamic CT.

    PubMed

    David, Matthias; Karmrodt, Jens; Bletz, Carsten; David, Sybil; Herweling, Annette; Kauczor, Hans-Ulrich; Markstaller, Klaus

    2005-11-01

    To study the dynamics of lung compartments by dynamic CT (dCT) imaging during uninterrupted pressure-controlled ventilation (PCV) and different positive end-expiratory pressure (PEEP) settings in healthy and damaged lungs. Experimental animal investigation. Experimental animal facility of a university department. In seven anesthetized pigs, static inspiratory pressure volume curves were obtained to identify the individual lower inflection point (LIP) before and after saline solution lung lavage. During PCV, PEEP was adjusted 5 millibars (mbar) below the individually determined LIP (LIP - 5), at the LIP, and 5 mbar above the LIP (LIP + 5). Measurements were repeated before and after induction of lung damage. Hemodynamics, arterial and mixed venous blood gases, and dCT imaging in one juxtadiaphragmatic slice (effective temporal resolution of 100 ms) were assessed during uninterrupted PCV in series of three successive respiratory cycles. The mean fractional area (FA) of the hyperinflated lung (FA-H), mean FA of ventilated lung, mean FA of poorly ventilated lung, and mean FA of nonventilated lung (FA-NV), and the change in FA of the whole lung area (DeltaFA) were compared at different PEEP settings. Calculated pulmonary shunt (Qs/Qt) was compared to FA-NV. LIP + 5 decreased the amount of atelectasis (FA-NV) and increased hyperinflation (FA-H) in healthy and injured lungs. Cyclic changes of atelectasis (DeltaFA-NV) and hyperinflation (DeltaFA-H) were observed in both healthy and injured lungs. In the injured but not in the healthy lungs, the amount of cyclic changes of atelectasis and hyperinflation were independent from the adjusted PEEP level. FA-NV correlated with the calculated Qs/Qt, with a slight overestimation (mean +/- SEM, 2.1 +/- 4.1%). dCT imaging allows the following: (1) the quantification of the extent of atelectasis, ventilated, poorly ventilated, and hyperinflated lung parenchyma during ongoing mechanical ventilation; (2) the detection and quantification

  8. [Immediate postoperative respiratory complications after coronary surgery].

    PubMed

    Quadrelli, S A; Montiel, G; Roncoroni, A J; Raimondi, A

    1997-01-01

    The influence of anesthesia, surgical procedure and special conditions of open-heart surgery upon respiratory function alterations is analyzed. Hypoxemia (present even in non-complicated open heart surgery) can be due to alveolar hypoventilation, ventilation-perfusion mismatch or shunt. The origin of atelectasias (present in 50-92% of patients) and pleural effusion (42-87%) is discussed. Phrenic nerve damage is usually secondary to thermal injury. Other less common complications are discussed. The influence of age, smoking and previous pulmonary diseases on respiratory complications is analyzed. Respiratory care after heart surgery (as time and requisites of extubations) and results of different methods (CPAP, PEEP, incentive inspirometry) are reviewed.

  9. Solid State Research.

    DTIC Science & Technology

    2007-11-02

    the resolution is two times the melt -zone radii. 15 3-4 Volumetric removal rate vs bias temperature using a 4-jUm laser beam spot size and the...using piezoelectric-electrophoretic (PE-EP) injection coupled to epifluorescent laser detection and gel-filled capillaries. 22 4-3 Single -droplet PE...Electron. Mater. PRESENTATION Efficient, Single -Mode, 1.5-mJ, Passively g-Switched Diode- Pumped Nd:YAG Laser T. Y. Fan J. J. Zayhowski R. Afzal

  10. Fluorescent supramolecular micelles for imaging-guided cancer therapy

    NASA Astrophysics Data System (ADS)

    Sun, Mengmeng; Yin, Wenyan; Dong, Xinghua; Yang, Wantai; Zhao, Yuliang; Yin, Meizhen

    2016-02-01

    A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth-inhibitory studies reveal a better therapeutic effect of FSMs after CPT encapsulation when compared with the free CPT drug. The multifunctional FSM nanomedicine platform as a nanovehicle has great potential for fluorescence imaging-guided cancer therapy.A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth

  11. Pneumomediastinum complicated by subclavian central venous catheterization in a severe thoracic trauma patient.

    PubMed

    Chen, Liang-Chih; Tzao, Chi; Liaw, Wen-Jinn; Horng, Huei-Chi; Cherng, Chen-Hwan; Wong, Chih-Shung; Wu, Ching-Tang

    2007-09-01

    Pneumomediastinum is a rare event in subclavian central venous catheterization. However in severe thoracotraumatized patients, such as with bilateral hemopneumothorax, the catherization may be hazardous and made complex by occurrence pneumomediastinum, even the procedure is rightly carried out. We suggest that in such a risky condition, if it is mandatory, it should be carried out in a more placid condition, such as avoidance of high PEEP ventilation, setting lower tidal volume, or brief interruption of positive ventilation, to reduce the likelihood of unperceivable pneumomediastinum.

  12. The Lazarus phenomenon

    PubMed Central

    Adhiyaman, Vedamurthy; Adhiyaman, Sonja; Sundaram, Radha

    2007-01-01

    Even though Lazarus phenomenon is rare, it is probably under reported. There is no doubt that Lazarus phenomenon is a reality but so far the scientific explanations have been inadequate. So far the only plausible explanation at least in some cases is auto-PEEP and impaired venous return. In patients with PEA or asystole, dynamic hyperinflation should considered as a cause and a short period of apnoea (30-60 seconds) should be tried before stopping resuscitation. Since ROSC occurred within 10 minutes in most cases, patients should be passively monitored for at least 10 minutes after the cessation of CPR before confirming death. PMID:18065707

  13. Lung Transcriptomics during Protective Ventilatory Support in Sepsis-Induced Acute Lung Injury.

    PubMed

    Acosta-Herrera, Marialbert; Lorenzo-Diaz, Fabian; Pino-Yanes, Maria; Corrales, Almudena; Valladares, Francisco; Klassert, Tilman E; Valladares, Basilio; Slevogt, Hortense; Ma, Shwu-Fan; Villar, Jesus; Flores, Carlos

    2015-01-01

    Acute lung injury (ALI) is a severe inflammatory process of the lung. The only proven life-saving support is mechanical ventilation (MV) using low tidal volumes (LVT) plus moderate to high levels of positive end-expiratory pressure (PEEP). However, it is currently unknown how they exert the protective effects. To identify the molecular mechanisms modulated by protective MV, this study reports transcriptomic analyses based on microarray and microRNA sequencing in lung tissues from a clinically relevant animal model of sepsis-induced ALI. Sepsis was induced by cecal ligation and puncture (CLP) in male Sprague-Dawley rats. At 24 hours post-CLP, septic animals were randomized to three ventilatory strategies: spontaneous breathing, LVT (6 ml/kg) plus 10 cmH2O PEEP and high tidal volume (HVT, 20 ml/kg) plus 2 cmH2O PEEP. Healthy, non-septic, non-ventilated animals served as controls. After 4 hours of ventilation, lung samples were obtained for histological examination and gene expression analysis using microarray and microRNA sequencing. Validations were assessed using parallel analyses on existing publicly available genome-wide association study findings and transcriptomic human data. The catalogue of deregulated processes differed among experimental groups. The 'response to microorganisms' was the most prominent biological process in septic, non-ventilated and in HVT animals. Unexpectedly, the 'neuron projection morphogenesis' process was one of the most significantly deregulated in LVT. Further support for the key role of the latter process was obtained by microRNA studies, as four species targeting many of its genes (Mir-27a, Mir-103, Mir-17-5p and Mir-130a) were found deregulated. Additional analyses revealed 'VEGF signaling' as a central underlying response mechanism to all the septic groups (spontaneously breathing or mechanically ventilated). Based on this data, we conclude that a co-deregulation of 'VEGF signaling' along with 'neuron projection morphogenesis

  14. Alveolar recruitment maneuver in refractory hypoxemia and lobar atelectasis after cardiac surgery: A case report

    PubMed Central

    2012-01-01

    Objective This case report describes an unusual presentation of right upper lobe atelectasis associated with refractory hypoxemia to conventional alveolar recruitment maneuvers in a patient soon after coronary artery bypass grafting surgery. Method Case-report. Results The alveolar recruitment with PEEP = 40cmH2O improved the patient’s atelectasis and hypoxemia. Conclusion In the present report, the unusual alveolar recruitment maneuver with PEEP 40cmH2O showed to be safe and efficient to reverse refractory hypoxemia and uncommon atelectasis in a patient after cardiac surgery. PMID:22726992

  15. Atelectasis formation during anesthesia: causes and measures to prevent it.

    PubMed

    Hedenstierna, G; Rothen, H U

    2000-01-01

    Pulmonary gas exchange is regularly impaired during general anaesthesia with mechanical ventilation. This results in decreased oxygenation of blood. A major cause is collapse of lung tissue (atelectasis), which can be demonstrated by computed tomography but not by conventional chest x-ray. Collapsed lung tissue is present in 90% of all subjects, both during spontaneous breathing and after muscle paralysis, and whether intravenous or inhalational anaesthetics are used. There is a correlation between the amount of atelectasis and pulmonary shunt. Shunt does not increase with age. In obese patients, larger atelectatic areas are present than in lean ones. Finally, patients with chronic obstructive lung disease may show less or even no atelectasis. There are different procedures that can be used in order to prevent atelectasis or to reopen collapsed lung tissue. The application of positive end-expiratory pressure (PEEP) has been tested in several studies. On the average, arterial oxygenation does not improve markedly, and atelectasis may persist. Further, reopened lung units re-collapse rapidly after discontinuation of PEEP. Inflation of the lungs to an airway pressure of 40 cm H2O, maintained for 7-8 seconds (recruitment or "vital capacity" manoeuvre), re-expands all previously collapsed lung tissue. During induction of anaesthesia, the use of a gas mixture, that includes a poorly absorbed gas such as nitrogen, may prevent the early formation of atelectasis. During ongoing anaesthesia, pulmonary collapse reappears slowly if a low fraction of oxygen in nitrogen is used for the ventilation of the lungs after a previous VC-manoeuvre. On the other hand, ventilation of the lungs with pure oxygen results in a rapid reappearance of atelectasis. Thus, ventilation during anaesthesia should be done if possible with a moderate fraction of inspired oxygen (FIO2, e.g. 0.3-0.4). Alternatively, if the lungs are ventilated with a high inspiratory fraction of oxygen, the use of PEEP

  16. Alveolar recruitment maneuver in refractory hypoxemia and lobar atelectasis after cardiac surgery: a case report.

    PubMed

    Herbst-Rodrigues, Marcus Vinicius; Carvalho, Vitor Oliveira; Abrahao, Ludhmila Hajjar; Nozawa, Emilia; Feltrim, Maria Ignez Zanetti; Gomes-Galas, Filomena Regina Barbosa

    2012-06-22

    This case report describes an unusual presentation of right upper lobe atelectasis associated with refractory hypoxemia to conventional alveolar recruitment maneuvers in a patient soon after coronary artery bypass grafting surgery. Case-report. The alveolar recruitment with PEEP = 40 cm H2O improved the patient's atelectasis and hypoxemia. In the present report, the unusual alveolar recruitment maneuver with PEEP 40 cm H2O showed to be safe and efficient to reverse refractory hypoxemia and uncommon atelectasis in a patient after cardiac surgery.

  17. A novel mechanical lung model of pulmonary diseases to assist with teaching and training

    PubMed Central

    Chase, J Geoffrey; Yuta, Toshinori; Mulligan, Kerry J; Shaw, Geoffrey M; Horn, Beverley

    2006-01-01

    Background A design concept of low-cost, simple, fully mechanical model of a mechanically ventilated, passively breathing lung is developed. An example model is built to simulate a patient under mechanical ventilation with accurate volumes and compliances, while connected directly to a ventilator. Methods The lung is modelled with multiple units, represented by rubber bellows, with adjustable weights placed on bellows to simulate compartments of different superimposed pressure and compliance, as well as different levels of lung disease, such as Acute Respiratory Distress Syndrome (ARDS). The model was directly connected to a ventilator and the resulting pressure volume curves recorded. Results The model effectively captures the fundamental lung dynamics for a variety of conditions, and showed the effects of different ventilator settings. It was particularly effective at showing the impact of Positive End Expiratory Pressure (PEEP) therapy on lung recruitment to improve oxygenation, a particulary difficult dynamic to capture. Conclusion Application of PEEP therapy is difficult to teach and demonstrate clearly. Therefore, the model provide opportunity to train, teach, and aid further understanding of lung mechanics and the treatment of lung diseases in critical care, such as ARDS and asthma. Finally, the model's pure mechanical nature and accurate lung volumes mean that all results are both clearly visible and thus intuitively simple to grasp. PMID:16919173

  18. Functional flexibility in wild bonobo vocal behaviour

    PubMed Central

    Archbold, Jahmaira; Zuberbühler, Klaus

    2015-01-01

    A shared principle in the evolution of language and the development of speech is the emergence of functional flexibility, the capacity of vocal signals to express a range of emotional states independently of context and biological function. Functional flexibility has recently been demonstrated in the vocalisations of pre-linguistic human infants, which has been contrasted to the functionally fixed vocal behaviour of non-human primates. Here, we revisited the presumed chasm in functional flexibility between human and non-human primate vocal behaviour, with a study on our closest living primate relatives, the bonobo (Pan paniscus). We found that wild bonobos use a specific call type (the “peep”) across a range of contexts that cover the full valence range (positive-neutral-negative) in much of their daily activities, including feeding, travel, rest, aggression, alarm, nesting and grooming. Peeps were produced in functionally flexible ways in some contexts, but not others. Crucially, calls did not vary acoustically between neutral and positive contexts, suggesting that recipients take pragmatic information into account to make inferences about call meaning. In comparison, peeps during negative contexts were acoustically distinct. Our data suggest that the capacity for functional flexibility has evolutionary roots that predate the evolution of human speech. We interpret this evidence as an example of an evolutionary early transition away from fixed vocal signalling towards functional flexibility. PMID:26290789

  19. 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.

  20. Assessment of mechanical ventilation parameters on respiratory mechanics.

    PubMed

    Pidaparti, Ramana M; Koombua, Kittisak; Ward, Kevin R

    2012-01-01

    Better understanding of airway mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems in intensive-care medicine, as well as pulmonary medicine. Mechanical ventilation depends on several parameters, all of which affect the patient outcome. As there are no systematic numerical investigations of the role of mechanical ventilation parameters on airway mechanics, the objective of this study was to investigate the role of mechanical ventilation parameters on airway mechanics using coupled fluid-solid computational analysis. For the airway geometry of 3 to 5 generations considered, the simulation results showed that airflow velocity increased with increasing airflow rate. Airway pressure increased with increasing airflow rate, tidal volume and positive end-expiratory pressure (PEEP). Airway displacement and airway strains increased with increasing airflow rate, tidal volume and PEEP form mechanical ventilation. Among various waveforms considered, sine waveform provided the highest airflow velocity and airway pressure while descending waveform provided the lowest airway pressure, airway displacement and airway strains. These results combined with optimization suggest that it is possible to obtain a set of mechanical ventilation strategies to avoid lung injuries in patients.

  1. 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.

  2. A numerical model of the respiratory modulation of pulmonary shunt and PaO2 oscillations for acute lung injury.

    PubMed

    Beda, Alessandro; Jandre, Frederico C; Giannella-Neto, Antonio

    2010-03-01

    It is an accepted hypothesis that the amplitude of the respiratory-related oscillations of arterial partial pressure of oxygen (DeltaPaO2) is primarily modulated by fluctuations of pulmonary shunt (Deltas), the latter generated mainly by cyclic alveolar collapse/reopening, when present. A better understanding of the relationship between DeltaPaO2, Deltas, and cyclic alveolar collapse/reopening can have clinical relevance for minimizing the severe lung damage that the latter can cause, for example during mechanical ventilation (MV) of patients with acute lung injury (ALI). To this aim, we numerically simulated the effect of such a relationship on an animal model of ALI under MV, using a combination of a model of lung gas exchange during tidal ventilation with a model of time dependence of shunt on alveolar collapse/opening. The results showed that: (a) the model could adequately replicate published experimental results regarding the complex dependence of DeltaPaO2 on respiratory frequency, driving pressure (DeltaP), and positive end-expiratory pressure (PEEP), while simpler models could not; (b) such a replication strongly depends on the value of the model parameters, especially of the speed of alveolar collapse/reopening; (c) the relationship between DeltaPaO2 and Deltas was overall markedly nonlinear, but approximately linear for PEEP>or=6 cmH2O, with very large DeltaPaO2 associated with relatively small Deltas.

  3. Fluorescent supramolecular micelles for imaging-guided cancer therapy.

    PubMed

    Sun, Mengmeng; Yin, Wenyan; Dong, Xinghua; Yang, Wantai; Zhao, Yuliang; Yin, Meizhen

    2016-03-07

    A novel smart fluorescent drug delivery system composed of a perylene diimide (PDI) core and block copolymer poly(d,l-lactide)-b-poly(ethyl ethylene phosphate) is developed and named as PDI-star-(PLA-b-PEEP)8. The biodegradable PDI-star-(PLA-b-PEEP)8 is a unimolecular micelle and can self-assemble into supramolecular micelles, called as fluorescent supramolecular micelles (FSMs), in aqueous media. An insoluble drug camptothecin (CPT) can be effectively loaded into the FSMs and exhibits pH-responsive release. Moreover, the FSMs with good biocompatibility can also be employed as a remarkable fluorescent probe for cell labelling because the maximum emission of PDI is beneficial for bio-imaging. The flow cytometry and confocal laser scanning microscopy analysis demonstrate that the micelles are easily endocytosed by cancer cells. In vitro and in vivo tumor growth-inhibitory studies reveal a better therapeutic effect of FSMs after CPT encapsulation when compared with the free CPT drug. The multifunctional FSM nanomedicine platform as a nanovehicle has great potential for fluorescence imaging-guided cancer therapy.

  4. Goal-directed mechanical ventilation: are we aiming at the right goals? A proposal for an alternative approach aiming at optimal lung compliance, guided by esophageal pressure in acute respiratory failure.

    PubMed

    Soroksky, Arie; Esquinas, Antonio

    2012-01-01

    Patients with acute respiratory failure and decreased respiratory system compliance due to ARDS frequently present a formidable challenge. These patients are often subjected to high inspiratory pressure, and in severe cases in order to improve oxygenation and preserve life, we may need to resort to unconventional measures. The currently accepted ARDSNet guidelines are characterized by a generalized approach in which an algorithm for PEEP application and limited plateau pressure are applied to all mechanically ventilated patients. These guidelines do not make any distinction between patients, who may have different chest wall mechanics with diverse pathologies and different mechanical properties of their respiratory system. The ability of assessing pleural pressure by measuring esophageal pressure allows us to partition the respiratory system into its main components of lungs and chest wall. Thus, identifying the dominant factor affecting respiratory system may better direct and optimize mechanical ventilation. Instead of limiting inspiratory pressure by plateau pressure, PEEP and inspiratory pressure adjustment would be individualized specifically for each patient's lung compliance as indicated by transpulmonary pressure. The main goal of this approach is to specifically target transpulmonary pressure instead of plateau pressure, and therefore achieve the best lung compliance with the least transpulmonary pressure possible.

  5. 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

  6. Postflight hardware evaluation 360T026 (RSRM-26, STS-47)

    NASA Technical Reports Server (NTRS)

    Nielson, Greg

    1993-01-01

    The final report for the Clearfield disassembly evaluation and a continuation of the KSC postflight assessment for the 360T026 (STS-47) Redesigned Solid Rocket Motor (RSRM) flight set is provided. All observed hardware conditions were documented on PFOR's and are included in Appendices A, B, and C. Appendices D and E contain the measurements and safety factor data for the nozzle and insulation components. This report, along with the KSC Ten-Day Postflight Hardware Evaluation Report (TWR-64203), represents a summary of the 360T026 hardware evaluation. The as-flown hardware configuration is documented in TWR-60472. Disassembly evaluation photograph numbers are logged in TWA-1987. The 360T026 flight set disassembly evaluations described were performed at the RSRM Refurbishment Facility in Clearfield, Utah. The final factory joint demate occurred on 12 April 1993. Detailed evaluations were performed in accordance with the Clearfield Postflight Engineering Evaluation Plan (PEEP), TWR-50051, Revision A. All observations were compared against limits that are also defined in the PEEP. These limits outline the criteria for categorizing the observations as acceptable, reportable, or critical. Hardware conditions that were unexpected and/or determined to be reportable or critical were evaluated by the applicable CPT and tracked through the PFAR system.

  7. 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.

  8. Sequelae of the adult respiratory distress syndrome.

    PubMed Central

    Hert, R.; Albert, R. K.

    1994-01-01

    Most survivors of ARDS have persistent mild reductions of TLCO even as long as a year after their episode. The lung volumes and flows return to normal in most instances, although a subset of patients will have persistent impairment. Both obstructive and restrictive deficits may be seen. This group may be predicted by the degree of acute lung injury assessed by the level of FIO2, PEEP, and gas exchange abnormality that exists in the first few days. In the first year after ARDS most physiological abnormalities will improve, but if deficits persist at one year further improvement is unlikely. Although many patients report dyspnoea following ARDS, the symptom does not correlate with abnormalities of pulmonary function. The possibility that conventional management may augment the degree of acute injury and worsen outcome must be considered. The effects of chronic hyperoxia in humans with acute lung injury or those of high levels of PEEP compared with low levels are not known. Exploring new ventilator management strategies while we await more specific treatment directed at the primary problem of acute lung inflammation will hopefully reduce acute mortality as well as acute and chronic morbidity. Images PMID:8153946

  9. Transpulmonary pressure monitoring during mechanical ventilation: a bench-to-bedside review.

    PubMed

    Mietto, Cristina; Malbrain, Manu L N G; Chiumello, Davide

    2015-01-01

    Different ventilation strategies have been suggested in the past in patients with acute respiratory distress syndrome (ARDS). Airway pressure monitoring alone is inadequate to assure optimal ventilatory support in ARDS patients. The assessment of transpulmonary pressure (PTP) can help clinicians to tailor mechanical ventilation to the individual patient needs. Transpulmonary pressure monitoring, defined as airway pressure (Paw) minus intrathoracic pressure (ITP), provides essential information about chest wall mechanics and its effects on the respiratory system and lung mechanics. The positioning of an esophageal catheter is required to measure the esophageal pressure (Peso), which is clinically used as a surrogate for ITP or pleural pressure (Ppl), and calculates the transpulmonary pressure. The benefits of such a ventilation approach are avoiding excessive lung stress and individualizing the positive end-expiratory pressure (PEEP) setting. The aim is to prevent over-distention of alveoli and the cyclic recruitment/derecruitment or shear stress of lung parenchyma, mechanisms associated with ventilator-induced lung injury (VILI). Knowledge of the real lung distending pressure, i.e. the transpulmonary pressure, has shown to be useful in both controlled and assisted mechanical ventilation. In the latter ventilator modes, Peso measurement allows one to assess a patient's respiratory effort, patient-ventilator asynchrony, intrinsic PEEP and the calculation of work of breathing. Conditions that have an impact on Peso, such as abdominal hypertension, will also be discussed briefly.

  10. Postflight hardware evaluation 360T025 (RSRM-25, STS-46)

    NASA Technical Reports Server (NTRS)

    Morgan, Ferral

    1993-01-01

    The final report for the Clearfield disassembly evaluation and a continuation of the KSC postflight assessment for the 360T025 (STS-46) Redesign Solid Rocket Motor (RSRM) flight set is presented. All observed hardware conditions were documented on PFOR's and are included in Appendices A through C. Appendices D and E contain the measurements and safety factor data for the nozzle and insulation components. Along with the KSC Ten-Day Postflight Hardware Evaluation Report (TWR-60687), a summary of the 360T025 hardware evaluation is provided. The as-flown hardware configuration is documented in TWR-60470. Disassembly evaluation photograph numbers are logged in TWA-1986. The 360T025 flight set disassembly evaluations described were performed at the RSRM Refurbishment Facility in Clearfield, Utah. The final factory joint demate occurred on 16 Mar. 1993. Detailed evaluations were performed in accordance with the Clearfield PEEP, TWR-50051, Revision A. All observations were compared against limits that are also defined in the PEEP. These limits outline the criteria for categorizing the observations as acceptable, reportable, or critical. Hardware conditions that were unexpected and/or determined to be reportable or critical were evaluated by the applicable CPT and tracked through the PFAR system.

  11. Postflight hardware evaluation (RSRM-29, STS-54)

    NASA Astrophysics Data System (ADS)

    1993-09-01

    This document is the final report for the Clearfield disassembly evaluation and a continuation of the KSC postflight assessment for the RSRM-29 flight set. All observed hardware conditions were documented on PFOR's and are included in Appendices A, B, and C. Appendices D and E contain the measurements and safety factor data for the nozzle and insulation components. This report, along with the KSC Ten-Day Postflight Hardware Evaluation Report (TWR-64221), represents a summary of the RSRM-29 hardware evaluation. Disassembly evaluation photograph numbers are logged in TWA-1990. The RSRM-29 flight set disassembly evaluations described in this document were performed at the RSRM Refurbishment Facility in Clearfield, Utah. The final factory joint demate occurred on September 9, 1993. Detailed evaluations were performed in accordance with the Clearfield PEEP, TWR-50051, Revision A. All observations were compared against limits that are also defined in the PEEP. These limits outline the criteria for categorizing the observations as acceptable, reportable, or critical. Hardware conditions that were unexpected and/or determined to be reportable or critical were evaluated by the applicable CPT and tracked through the PFAR system.

  12. Intraoperative mechanical ventilation strategies for obese patients: a systematic review and network meta-analysis.

    PubMed

    Wang, C; Zhao, N; Wang, W; Guo, Libo; Guo, Lei; Chi, C; Wang, X; Pi, X; Cui, Y; Li, E

    2015-06-01

    Several intraoperative ventilation strategies are available for obese patients. However, the same ventilation interventions have exhibited different effects on PaO2 /FIO2 concerning obese patients in different trials, and the issue remains controversial. Therefore, we conducted a network meta-analysis to identify the optimal mechanical ventilation strategy. 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 June 2014, and the PaO2 /FIO2 in obese patients given different mechanical ventilation strategies was assessed. We assessed the studies for eligibility and extracted data and then pooled the data and used a Bayesian fixed-effect model to combine direct comparisons with indirect evidence. Eligible studies evaluated different ventilation strategies for obese patients and reported the intraoperative PaO2 /FIO2 ratio, atelectasis and pulmonary compliance. Thirteen randomized controlled trials were included for network meta-analysis, including 476 patients who received 1 of 12 ventilation strategies. Volume-controlled ventilation with higher PEEP plus single recruitment manoeuvres (VCV + higher PEEP + single RM) was associated with the highest PaO2 /FiO2 ratio, improving intraoperative pulmonary compliance and reducing the incidence of intraoperative atelectasis. © 2015 World Obesity.

  13. Effects of body temperature on ventilator-induced lung injury.

    PubMed

    Akinci, Ozkan I; Celik, Mehmet; Mutlu, Gökhan M; Martino, Janice M; Tugrul, Simru; Ozcan, Perihan E; Yilmazbayhan, Dilek; Yeldandi, Anjana V; Turkoz, Kemal H; Kiran, Bayram; Telci, Lütfi; Cakar, Nahit

    2005-03-01

    To evaluate the effects of body temperature on ventilator-induced lung injury. Thirty-four male Sprague-Dawley rats were randomized into 6 groups based on their body temperature (normothermia, 37 +/- 1 degrees C; hypothermia, 31 +/- 1 degrees C; hyperthermia, 41 +/- 1 degrees C). Ventilator-induced lung injury was achieved by ventilating for 1 hour with pressure-controlled ventilation mode set at peak inspiratory pressure (PIP) of 30 cmH2O (high pressure, or HP) and positive end-expiratory pressure (PEEP) of 0 cmH2O. In control subjects, PIP was set at 14 cmH2O (low pressure, or LP) and PEEP set at 0 cmH2O. Systemic chemokine and cytokine (tumor necrosis factor alpha , interleukin 1 beta , interleukin 6, and monocyte chemoattractant protein 1) levels were measured. The lungs were assessed for histological changes. Serum chemokines and cytokines were significantly elevated in the hyperthermia HP group compared with all 3 groups, LP (control), normothermia HP, and hypothermia HP. Oxygenation was better but not statistically significant in hypothermia HP compared with other HP groups. Cumulative mean histology scores were higher in hyperthermia HP and normothermia HP groups compared with control and normothermia HP groups. Concomitant hyperthermia increased systemic inflammatory response during HP ventilation. Although hypothermia decreased local inflammation in the lung, it did not completely attenuate systemic inflammatory response associated with HP ventilation.

  14. On the interaction between respiratory compartments during passive expiration in ARDS patients.

    PubMed

    Chelucci, Gian-Luca; Locchi, Fabrizio; Zin, Walter A

    2005-01-15

    Relaxed expiratory volume-time profile has been frequently analysed by fitting exponential functions of time to one- or two-compartment models. In the latter case, the two exponential constants are assumed as representing the time constants of both compartments. Least-square fittings on the experimental data of five consecutive mechanically ventilated supine patients with acute respiratory distress syndrome (ARDS) were performed using rate-constants (flow/volume ratio) as parameters in order to obtain the model matching. Passive expiratory volume-time curves were recorded under PEEP = 0 and 13.6 +/- 3.3 S.D. cmH2O conditions. Model matching was optimal with significant, reliable parameter values. As a result, the use of a PEEP in ARDS patients: (a) delayed expiration; (b) decreased the percentage initial volume contribution of the slow-emptying compartment; and, (c) modified the interaction between compartments. The volume-time profile of the second compartment was found to increase at the beginning of expiration, and, then, progressively decayed towards zero, showing a maximum, although the overall curve decreased throughout expiration.

  15. Respiratory drive and pulmonary mechanics during haemodialysis with ultrafiltration in ventilated patients.

    PubMed

    Huang, C C; Tsai, Y H; Lin, M C; Yang, C T; Hsieh, M J; Lan, R S

    1997-10-01

    The improvements of respiratory drive and pulmonary mechanics which follow haemodialysis with ultrafiltration in mechanically ventilated renal failure patients seem predictable but have not been studied before. In this study, 14 renal failure patients with stable haemodynamics mechanically ventilated with pressure support ventilation (PSV) were enrolled. Respiratory drive (represented as P0.1), pulmonary mechanics, breathing pattern, arterial blood gas and haemodynamics were measured according to the time schedule: pre-dialysis (Time 0), and at 60, 120, 180, 240 minutes thereafter. Following the removal of excess lung water during haemodialysis, auto-PEEP and patient's work of breathing (WOBp) decreased gradually. P0.1 lessened progressively along with the improvement in pulmonary mechanics. The changes in auto-PEEP and WOBp correlated closely to the pre- and post-dialysis decline of P0.1 (delta P0.1). There was a negative, moderately significant correlation between the amount of fluid ultrafiltrated during dialysis (delta UF) and the delta P0.1 (R = -0.54). The breathing pattern remained stable during dialysis. No hypoventilation or hypoxaemia occurred despite the development of metabolic alkalosis induced by bicarbonate dialysate. We have shown that respiratory drive decreases gradually during bicarbonate haemodialysis. The improvements of pulmonary mechanics, rather than the rapid alkalization of body fluids, responds to the decrease of P0.1 in renal failure patients ventilated with PSV.

  16. Electrical impedance tomography: a method for monitoring regional lung aeration and tidal volume distribution?

    PubMed

    Frerichs, Inéz; Dargaville, Peter A; Dudykevych, Taras; Rimensberger, Peter C

    2003-12-01

    To demonstrate the monitoring capacity of modern electrical impedance tomography (EIT) as an indicator of regional lung aeration and tidal volume distribution. Short-term ventilation experiment in an animal research laboratory. One newborn piglet (body weight: 2 kg). Surfactant depletion by repeated bronchoalveolar lavage, surfactant administration. EIT scanning was performed at an acquisition rate of 13 images/s during two ventilatory manoeuvres performed before and after surfactant administration. During the scanning periods of 120 s the piglet was ventilated with a tidal volume of 10 ml/kg at positive end-expiratory pressures (PEEP) in the range of 0-30 cmH(2)O, increasing and decreasing in 5 cmH(2)O steps. Local changes in aeration and ventilation with PEEP were visualised by EIT scans showing the regional shifts in end-expiratory lung volume and distribution of tidal volume, respectively. In selected regions of interest EIT clearly identified the changes in local aeration and tidal volume distribution over time and after surfactant treatment as well as the differences between stepwise inflation and deflation. Our data indicate that modern EIT devices provide an assessment of regional lung aeration and tidal volume and allow evaluation of immediate effects of a change in ventilation or other therapeutic intervention. Future use of EIT in a clinical setting is expected to optimise the selection of appropriate ventilation strategies.

  17. Linking lung function and inflammatory responses in ventilator-induced lung injury.

    PubMed

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

    2011-01-01

    Despite decades of research, the mechanisms of ventilator-induced lung injury are poorly understood. We used strain-dependent responses to mechanical ventilation in mice to identify associations between mechanical and inflammatory responses in the lung. BALB/c, C57BL/6, and 129/Sv mice were ventilated using a protective [low tidal volume and moderate positive end-expiratory pressure (PEEP) and recruitment maneuvers] or injurious (high tidal volume and zero PEEP) ventilation strategy. Lung mechanics and lung volume were monitored using the forced oscillation technique and plethysmography, respectively. Inflammation was assessed by measuring numbers of inflammatory cells, cytokine (IL-6, IL-1β, and TNF-α) levels, and protein content of the BAL. Principal components factor analysis was used to identify independent associations between lung function and inflammation. Mechanical and inflammatory responses in the lung were dependent on ventilation strategy and mouse strain. Three factors were identified linking 1) pulmonary edema, protein leak, and macrophages, 2) atelectasis, IL-6, and TNF-α, and 3) IL-1β and neutrophils, which were independent of responses in lung mechanics. This approach has allowed us to identify specific inflammatory responses that are independently associated with overstretch of the lung parenchyma and loss of lung volume. These data provide critical insight into the mechanical responses in the lung that drive local inflammation in ventilator-induced lung injury and the basis for future mechanistic studies in this field.

  18. Final postflight hardware evaluation report RSRM-28 (STS-53)

    NASA Technical Reports Server (NTRS)

    Starrett, William David, Jr.

    1993-01-01

    The final report for the Clearfield disassembly evaluation and a continuation of the KSC postflight assessment for the RSRM-28 (STS-53) RSRM flight set is presented. All observed hardware conditions were documented on PFOR's and are included in Appendices A through C. Appendices D and E contain the measurements and safety factor data for the nozzle and insulation components. This report, along with the KSC Ten-Day Postflight Hardware Evaluation Report (TWR-64215), represents a summary of the RSRM-28 hardware evaluation. The as-flown hardware configuration is documented in TWR-63638. Disassembly evaluation photograph numbers are logged in TWA-1989. The RSRM-28 flight set disassembly evaluations described were performed at the RSRM Refurbishment Facility in Clearfield, Utah. The final factory joint demate occurred on July 15, 1993. Additional time was required to perform the evaluation of the stiffener rings per special issue 4.1.5.2 because of the washout schedule. The release of this report was after completion of all special issues per program management direction. Detailed evaluations were performed in accordance with the Clearfield PEEP, TWR-50051, Revision A. All observations were compared against limits that are also defined in the PEEP. These limits outline the criteria for categorizing the observations as acceptable, reportable, or critical. Hardware conditions that were unexpected and/or determined to be reportable or critical were evaluated by the applicable team and tracked through the PFAR system.

  19. The effect of a bellows leak in an Ohmeda 7810 ventilator on room contamination, inspired oxygen, airway pressure, and tidal volume.

    PubMed

    Lampotang, Samsun; Sanchez, Justin C; Chen, Baixi; Gravenstein, Nikolaus

    2005-07-01

    We investigated the effect of a small bellows leak (bellows full at end-expiration) on inspired oxygen fraction (Fio(2)), exhaled tidal volume (Vt), airway pressure, and room contamination in an oxygen-driven anesthesia ventilator (Ohmeda 7810, Madison, WI). CO(2) concentration at the ventilator exhalation valve, Fio(2), Vt, and airway pressure were measured (n = 3) while ventilating a CO(2)-producing test lung at 8 breaths/min and an inspiratory/expiratory ratio of 1:2, with and without a bellows leak (4-mm-long tear). Set Vt was 400, 600, 800, and 1000 mL. Fresh gas flow (FGF) was 0.3 L/min O(2) and (a) 5.0 L/min air, (b) 2.0 L/min air, and (c) 0.2 L/min nitrogen. There was no clinical difference in Fio(2), Vt, PIP (peak inspiratory pressure) and PEEP (positive end-expiratory pressure), with and without a 4-mm bellows tear, at all FGFs and Vt settings. CO(2) at the ventilator exhalation valve was always nonzero with a bellows leak, indicating that CO(2)-laden circuit gas was contaminating the drive gas via the bellows leak. A 4-mm bellows tear in an Ohmeda 7810 ventilator allows anesthetic gases to contaminate ambient air but does not cause clinically significant changes in Fio(2), exhaled Vt, PIP, or PEEP.

  20. [The basics on mechanical ventilation support in acute respiratory distress syndrome].

    PubMed

    Tomicic, V; Fuentealba, A; Martínez, E; Graf, J; Batista Borges, J

    2010-01-01

    Acute Respiratory Distress Syndrome (ARDS) is understood as an inflammation-induced disruption of the alveolar endothelial-epithelial barrier that results in increased permeability and surfactant dysfunction followed by alveolar flooding and collapse. ARDS management relies on mechanical ventilation. The current challenge is to determine the optimal ventilatory strategies that minimize ventilator-induced lung injury (VILI) while providing a reasonable gas exchange. The data support that a tidal volume between 6-8 ml/kg of predicted body weight providing a plateau pressure < 30 cmH₂O should be used. High positive end expiratory pressure (PEEP) has not reduced mortality, nevertheless secondary endpoints are improved. The rationale used for high PEEP argues that it prevents cyclic opening and closing of airspaces, probably the major culprit of development of VILI. Chest computed tomography has contributed to our understanding of anatomic-functional distribution patterns in ARDS. Electric impedance tomography is a technique that is radiation-free, but still under development, that allows dynamic monitoring of ventilation distribution at bedside. Copyright © 2009 Elsevier España, S.L. y SEMICYUC. All rights reserved.

  1. Effects of vertical positioning on gas exchange and lung volumes in acute respiratory distress syndrome.

    PubMed

    Richard, Jean-Christophe M; Maggiore, Salvatore Maurizio; Mancebo, Jordi; Lemaire, François; Jonson, Bjorn; Brochard, Laurent

    2006-10-01

    Supine position may contribute to the loss of aerated lung volume in patients with acute respiratory distress syndrome (ARDS). We hypothesized that verticalization increases lung volume and improves gas exchange by reducing the pressure surrounding lung bases. Prospective observational physiological study in a medical ICU. In 16 patients with ARDS we measured arterial blood gases, pressure-volume curves of the respiratory system recorded from positive-end expiratory pressure (PEEP), and changes in lung volume in supine and vertical positions (trunk elevated at 45 degrees and legs down at 45 degrees ). Vertical positioning increased PaO(2) significantly from 94+/-33 to 142+/-49 mmHg, with an increase higher than 40% in 11 responders. The volume at 20 cmH(2)O measured on the PV curve from PEEP increased using the vertical position only in responders (233+/-146 vs. -8+/-9 1ml in nonresponders); this change was correlated to oxygenation change (rho=0.55). End-expiratory lung volume variation from supine to vertical and 1 h later back to supine, measured in 12 patients showed a significant increase during the 1-h upright period in responders (n=7) but not in nonresponders (n=5; 215+/-220 vs. 10+/-22 ml), suggesting a time-dependent recruitment. Vertical positioning is a simple technique that may improve oxygenation and lung recruitment in ARDS patients.

  2. New evidence in one-lung ventilation.

    PubMed

    Meleiro, H; Correia, I; Charco Mora, P

    2017-09-26

    Mechanical ventilation in thoracic surgery has undergone significant changes in recent years due to the implementation of the protective ventilation. This review will analyze recent ventilatory strategies in one-lung ventilation. A MEDLINE research was performed using Mesh term "One-Lung Ventilation" including randomized clinical trials, metanalysis, reviews and systematic reviews published in the last 6 years. Search was performed on 21st March 2017. A total of 75 articles were initially found. After title and abstract review 14 articles were included. Protective ventilation is not simply synonymous of low tidal volume ventilation, but it also includes routine use of PEEP and alveolar recruitment maneuver. New techniques are still in discussion namely PEEP adjustment, ratio inspiration:expiration, ideal type of anesthesia during one-lung ventilation and hypercapnic ventilation. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  3. Assessing the Potential Use of Eye-Tracking Triangulation for Evaluating the Usability of an Online Diabetes Exercise System.

    PubMed

    Schaarup, Clara; Hartvigsen, Gunnar; Larsen, Lars Bo; Tan, Zheng-Hua; Årsand, Eirik; Hejlesen, Ole Kristian

    2015-01-01

    The Online Diabetes Exercise System was developed to motivate people with Type 2 diabetes to do a 25 minutes low-volume high-intensity interval training program. In a previous multi-method evaluation of the system, several usability issues were identified and corrected. Despite the thorough testing, it was unclear whether all usability problems had been identified using the multi-method evaluation. Our hypothesis was that adding the eye-tracking triangulation to the multi-method evaluation would increase the accuracy and completeness when testing the usability of the system. The study design was an Eye-tracking Triangulation; conventional eye-tracking with predefined tasks followed by The Post-Experience Eye-Tracked Protocol (PEEP). Six Areas of Interests were the basis for the PEEP-session. The eye-tracking triangulation gave objective and subjective results, which are believed to be highly relevant for designing, implementing, evaluating and optimizing systems in the field of health informatics. Future work should include testing the method on a larger and more representative group of users and apply the method on different system types.

  4. Anaesthesia for bariatric surgery.

    PubMed

    Schumann, Roman

    2011-03-01

    Although many smaller studies have addressed anaesthetic care for bariatric surgical patients, comprehensive systematic literature reviews have yet to be compiled, and much evidence includes expert panel opinion. This review summarises study results in bariatric surgical patients regarding pre-anaesthesia evaluation, the perioperative impact of sleep-disordered breathing, airway management at anaesthetic induction and emergence, maintenance of anaesthesia, postoperative pain management, utility of clinical-care pathways and feasibility of outpatient bariatric surgery. The 'ramped' upper-body, reversed Trendelenburg position at anaesthetic induction and manual application of positive end-expiratory pressure (PEEP) is recommended. Intra-operative hypoxaemia can be treated with the combination of PEEP and recruitment manoeuvres, and attention to airway management at emergence is critical. Local anaesthetic wound infiltration and non-steroidal anti-inflammatory drugs should be part of multimodal opioid-sparing postoperative analgesia. Implementation of bariatric clinical-care pathways seems beneficial. Considering the prevalence of sleep apnoea in these patients, outpatient bariatric surgery remains controversial, but is probably safe for certain procedures, provided there is strict adherence to preoperative eligibility and home-care protocols.

  5. Irreversibility of birth-related changes in the pulmonary circulation.

    PubMed

    Levine, G L; Goetzman, B W; Milstein, J M; Bennett, S H

    1994-12-01

    We hypothesized that establishing conditions of hypoxia and fluid filling of the airways in lungs of newborns would reproduce the high levels of pulmonary vascular resistance (PVR) observed in the fetal state. We assessed the hemodynamics of the left pulmonary circulation of 1- to 3-day-old lambs during a variety of airway states while attempting to reestablish fetal conditions. Eleven animals were studied during both normoxemia and hypoxemia in a baseline airway state with a positive end-expiratory pressure (PEEP) of 4 cm H2O, and in experimental airway states, of atelectasis, and fluid filling to 15 and 30 mL/kg and with PEEP of 12 cm H2O. PVR increased while pulmonary blood flow decreased with all airway state changes as compared to baseline, suggesting a passive mechanism for these changes. With the addition of hypoxemia there was a further increase in PVR in all states accompanied by an increase in pulmonary blood flow, indicating that active vasoconstriction was responsible for the increase in PVR. The combined effects of hypoxemia and fluid filling, designed to approximate the fetal state, increased PVR to only 20-30% of fetal values. Thus, additional factors appear to be important in maintaining the high PVR of the fetal state. We speculate that ventilation of the lungs at birth irreversibly alters these factors.

  6. Atelectasis Induced by Thoracotomy Causes Lung Injury during Mechanical Ventilation in Endotoxemic Rats

    PubMed Central

    Kwon, Kun Young; Kim, Jin Mo; Quinn, Deborah A.; Hales, Charles A.; Seo, Jeong Wook

    2008-01-01

    Atelectasis can impair arterial oxygenation and decrease lung compliance. However, the effects of atelectasis on endotoxemic lungs during ventilation have not been well studied. We hypothesized that ventilation at low volumes below functional residual capacity (FRC) would accentuate lung injury in lipopolysaccharide (LPS)-pretreated rats. LPS-pretreated rats were ventilated with room air at 85 breaths/min for 2 hr at a tidal volume of 10 mL/kg with or without thoracotomy. Positive end-expiratory pressure (PEEP) was applied to restore FRC in the thoracotomy group. While LPS or thoracotomy alone did not cause significant injury, the combination of endotoxemia and thoracotomy caused significant hypoxemia and hypercapnia. The injury was observed along with a marked accumulation of inflammatory cells in the interstitium of the lungs, predominantly comprising neutrophils and mononuclear cells. Immunohistochemistry showed increased inducible nitric oxide synthase (iNOS) expression in mononuclear cells accumulated in the interstitium in the injury group. Pretreatment with PEEP or an iNOS inhibitor (1400 W) attenuated hypoxemia, hypercapnia, and the accumulation of inflammatory cells in the lung. In conclusion, the data suggest that atelectasis induced by thoracotomy causes lung injury during mechanical ventilation in endotoxemic rats through iNOS expression. PMID:18583875

  7. Atelectasis induced by thoracotomy causes lung injury during mechanical ventilation in endotoxemic rats.

    PubMed

    Choi, Won-Il; Kwon, Kun Young; Kim, Jin Mo; Quinn, Deborah A; Hales, Charles A; Seo, Jeong Wook

    2008-06-01

    Atelectasis can impair arterial oxygenation and decrease lung compliance. However, the effects of atelectasis on endotoxemic lungs during ventilation have not been well studied. We hypothesized that ventilation at low volumes below functional residual capacity (FRC) would accentuate lung injury in lipopolysaccharide (LPS)-pretreated rats. LPS-pretreated rats were ventilated with room air at 85 breaths/min for 2 hr at a tidal volume of 10 mL/kg with or without thoracotomy. Positive end-expiratory pressure (PEEP) was applied to restore FRC in the thoracotomy group. While LPS or thoracotomy alone did not cause significant injury, the combination of endotoxemia and thoracotomy caused significant hypoxemia and hypercapnia. The injury was observed along with a marked accumulation of inflammatory cells in the interstitium of the lungs, predominantly comprising neutrophils and mononuclear cells. Immunohistochemistry showed increased inducible nitric oxide synthase (iNOS) expression in mononuclear cells accumulated in the interstitium in the injury group. Pretreatment with PEEP or an iNOS inhibitor (1400 W) attenuated hypoxemia, hypercapnia, and the accumulation of inflammatory cells in the lung. In conclusion, the data suggest that atelectasis induced by thoracotomy causes lung injury during mechanical ventilation in endotoxemic rats through iNOS expression.

  8. [Application of lung recruitment maneuver in preterm infants with respiratory distress syndrome ventilated by proportional assist ventilation].

    PubMed

    Wu, Rong; Li, Na; Hu, Jinhui; Zha, Li; Zhu, Hongli; Zheng, Guofang; Zhao, Yuxiang; Feng, Zhichun

    2014-10-01

    To understand the effect of lung recruitment maneuver (LRM) with positive end-expiratory pressure (PEEP) on oxygenation and outcomes in preterm infants with respiratory distress syndrome (RDS) ventilated by proportional assist ventilation (PAV). From January 2012 to June 2013, thirty neonates with a diagnosis of RDS who required mechanical ventilation were divided randomly into LRM group (n=15, received an LRM and surport by PAV) and control group (n=15, only surport by PAV). There were no statistically significant differences in female (7 vs. 6); gestational age [(29.3±1.2) vs. (29.5±1.1) weeks]; body weight[(1,319±97) vs. (1,295±85) g]; Silverman Anderson(SA) score for babies at start of ventilation (7.3±1.2 vs. 6.9±1.4); initial FiO2 (0.54±0.12 vs. 0.50±0.10) between the two groups (all P>0.05). LRM entailed increments of 0.2 cmH2O (1 cmH2O=0.098 kPa) PEEP every 5 minutes, until fraction of inspired oxygen (FiO2)=0.25. Then PEEP was reduced and the lung volume was set on the deflation limb of the pressure/volume curve.When saturation of peripheral oxygen fell and FiO2 rose, we reincremented PEEP until SpO2 became stable. The related clinical indicators of the two group were observed. The doses of surfactant administered (1.1±0.3 vs. 1.5±0.5, P=0.027), Lowest FiO2 (0.29±0.05 vs. 0.39±0.06, P=0.000), time to lowest FiO2[ (103±18) vs. (368±138) min, P=0.000] and O2 dependency [(7.6±1.0) vs.( 8.8±1.3) days, P=0.021] in LRM group were lower than that in control group (all P<0.05). The maximum PEEP during the first 12 hours of life [(8.4±0.8) vs. (6.8±0.8) cmH2O, P=0.000] in LRM group were higher than that in control group (P<0.05). FiO2 levels progressively decreased (F=35.681, P=0.000) and a/AO2 Gradually increased (F=37.654, P=0.000). No adverse events and no significant differences in the outcomes were observed. LRM can reduce the doses of pulmonary surfactant administered, time of the respiratory support and the oxygen therapy in preterm

  9. Fast Versus Slow Recruitment Maneuver at Different Degrees of Acute Lung Inflammation Induced by Experimental Sepsis.

    PubMed

    Santos, Raquel S; Moraes, Lillian; Samary, Cynthia S; Santos, Cíntia L; Ramos, Maíra B A; Vasconcellos, Ana P; Horta, Lucas F; Morales, Marcelo M; Capelozzi, Vera L; Garcia, Cristiane S N B; Marini, John J; Gama de Abreu, Marcelo; Pelosi, Paolo; Silva, Pedro L; Rocco, Patricia R M

    2016-04-01

    Large tidal volume (VT) breaths or "recruitment maneuvers" (RMs) are used commonly to open collapsed lungs, but their effectiveness may depend on how the RM is delivered. We hypothesized that a stepped approach to RM delivery ("slow" RM) compared with a nonstepped ("fast" RM), when followed by decremental positive end-expiratory pressure (PEEP) titration to lowest dynamic elastance, would (1) yield a more homogeneous inflation of the lungs, thus reducing the PEEP obtained during post-RM titration; (2) produce less lung morphofunctional injury, regardless of the severity of sepsis-induced acute lung inflammation; and (3) result in less biological damage in severe, but not in moderate, acute lung inflammation. Sepsis was induced by cecal ligation and puncture surgery in 51 Wistar rats. After 48 hours, animals were anesthetized, mechanically ventilated (VT = 6 mL/kg), and stratified by PO2/fraction of inspired oxygen ratio into moderate (≥300) and severe (<300) acute lung inflammation groups. Each group was then subdivided randomly into 3 subgroups: (1) nonrecruited; (2) RM with continuous positive airway pressure (30 cm H2O for 30 seconds; CPAPRM or fast RM); and (3) RM with stepwise airway pressure increase (5 cm H2O/step, 8.5 seconds/step, 6 steps, 51 seconds; STEPRM or slow RM), with a maximum pressure hold for 10 seconds. All animals underwent decremental PEEP titration to determine the level of PEEP required to optimize dynamic compliance after RM and were then ventilated for 60 minutes with VT = 6 mL/kg, respiratory rate = 80 bpm, fraction of inspired oxygen = 0.4, and the newly adjusted PEEP for each animal. Respiratory mechanics, hemodynamics, and arterial blood gases were measured before and at the end of 60-minute mechanical ventilation. Lung histology and biological markers of inflammation and damage inflicted to endothelial cells were evaluated at the end of the 60-minute mechanical ventilation. Respiratory system mean airway pressure was lower in

  10. Respiratory mechanics and lung stress/strain in children with acute respiratory distress syndrome.

    PubMed

    Chiumello, Davide; Chidini, Giovanna; Calderini, Edoardo; Colombo, Andrea; Crimella, Francesco; Brioni, Matteo

    2016-12-01

    In sedated and paralyzed children with acute respiratory failure, the compliance of respiratory system and functional residual capacity were significantly reduced compared with healthy subjects. However, no major studies in children with ARDS have investigated the role of different levels of PEEP and tidal volume on the partitioned respiratory mechanic (lung and chest wall), stress (transpulmonary pressure) and strain (inflated volume above the functional residual capacity). The end-expiratory lung volume was measured using a simplified closed circuit helium dilution method. During an inspiratory and expiratory pause, the airway and esophageal pressure were measured. Transpulmonary pressure was computed as the difference between airway and esophageal pressure. Ten intubated sedated paralyzed healthy children and ten children with ARDS underwent a PEEP trial (4 and 12 cmH2O) with a tidal volume of 8, 10 and 12 ml/kgIBW. The two groups were comparable for age and BMI (2.5 [1.0-5.5] vs 3.0 [1.7-7.2] years and 15.1 ± 2.4 vs 15.3 ± 3.0 kg/m(2)). The functional residual capacity in ARDS patients was significantly lower as compared to the control group (10.4 [9.1-14.3] vs 16.6 [11.7-24.6] ml/kg, p = 0.04). The ARDS patients had a significantly lower respiratory system and lung compliance as compared to control subjects (9.9 ± 5.0 vs 17.8 ± 6.5, 9.3 ± 4.9 vs 16.9 ± 4.1 at 4 cmH2O of PEEP and 11.7 ± 5.8 vs 23.7 ± 6.8, 10.0 ± 4.9 vs 23.4 ± 7.5 at 12 cmH2O of PEEP). The compliance of the chest wall was similar in both groups (76.7 ± 30.2 vs 94.4 ± 76.4 and 92.6 ± 65.3 vs 90.0 ± 61.7 at 4 and 12 cmH2O of PEEP). The lung stress and strain were significantly higher in ARDS patients as compared to control subjects and were poorly related to airway pressure and tidal volume normalized for body weight. Airway pressures and tidal volume normalized to body weight are poor surrogates for lung stress and strain in mild pediatric ARDS

  11. 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

  12. 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 Central

    2013-01-01

    Introduction 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. Methods 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. Results 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). Conclusions nCPAP produced more effective tidal volume than FmCPAP in unconscious subjects. Trial registration ClinicalTrials.gov identifier: NCT01524614. PMID:24365207

  13. Inhaled nitric oxide in acute respiratory distress syndrome with and without septic shock requiring norepinephrine administration: a dose–response study

    PubMed Central

    Mourgeon, Eric; Puybasset, Louis; Law-Koune, Jean-Dominique; Lu, Qin; Abdennour, Lamine; Gallart, Lluis; Malassine, Patrick; Rao, GS Umamaheswara; Cluzel, Philippe; Bennani, Abdelhai; Coriat, Pierre; Rouby, Jean-Jacques

    1997-01-01

    Background: The aim of this prospective study was to assess whether the presence of septic shock could influence the dose response to inhaled nitric oxide (NO) in NO-responding patients with adult respiratory distress syndrome (ARDS). Results: Eight patients with ARDS and without septic shock (PaO2 = 95 ± 16 mmHg, PEEP = 0, FiO2 = 1.0), and eight patients with ARDS and septic shock (PaO2 = 88 ± 11 mmHg, PEEP = 0, FiO2 = 1.0) receiving exclusively norepinephrine were studied. All responded to 15 ppm inhaled NO with an increase in PaO2 of at least 40 mmHg, at FiO2 1.0 and PEEP 10 cmH2O. Inspiratory intratracheal NO concentrations were recorded continuously using a fast response time chemiluminescence apparatus. Seven inspiratory NO concentrations were randomly administered: 0.15, 0.45, 1.5, 4.5, 15, 45 and 150 ppm. In both groups, NO induced a dose-dependent decrease in mean pulmonary artery pressure (MPAP), pulmonary vascular resistance index (PVRI), and venous admixture (QVA/QT), and a dose-dependent increase in PaO2/FiO2 (P ≤ 0.012). Dose-response of MPAP and PVRI were similar in both groups with a plateau effect at 4.5 ppm. Dose-response of PaO2/FiO2 was influenced by the presence of septic shock. No plateau effect was observed in patients with septic shock and PaO2/FiO2 increased by 173 ± 37% at 150 ppm. In patients without septic shock, an 82 ± 26% increase in PaO2/FiO2 was observed with a plateau effect obtained at 15 ppm. In both groups, dose-response curves demonstrated a marked interindividual variability and in five patients pulmonary vascular effect and improvement in arterial oxygenation were dissociated. Conclusion: For similar NOinduced decreases in MPAP and PVRI in both groups, the increase in arterial oxygenation was more marked in patients with septic shock. PMID:11056694

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

    PubMed

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

    2009-03-01

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

  15. 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

  16. Maintenance of airway pressure during filter exchange due to auto-triggering.

    PubMed

    Engström, Joakim; Reinius, Henrik; Fröjd, Camilla; Hans, Jonsson; Hedenstierna, Göran; Larsson, Anders

    2014-08-01

    Daily routine ventilator-filter exchange interrupts the integrity of the ventilator circuit. We hypothesized that this might reduce positive airway pressure in mechanically ventilated ICU patients, inducing alveolar collapse and causing impaired oxygenation and compliance of the respiratory system. We studied 40 consecutive ICU subjects (P(aO2)/F(IO2) ratio ≤ 300 mm Hg), mechanically ventilated with pressure-regulated volume control or pressure support and PEEP ≥ 5 cm H2O. Before the filter exchange, (baseline) tidal volume, breathing frequency, end-inspiratory plateau pressure, and PEEP were recorded. Compliance of the respiratory system was calculated; F(IO2), blood pressure, and pulse rate were registered; and P(aO2), P(aCO2), pH, and base excess were measured. Measurements were repeated 15 and 60 min after the filter exchange. In addition, a bench test was performed with a precision test lung with similar compliance and resistance as in the clinical study. The exchange of the filter took 3.5 ± 1.2 s (mean ± SD). There was no significant change in P(aO2) (89 ± 16 mm Hg at baseline vs 86 ± 16 mm Hg at 15 min and 88 ± 18 mm Hg at 60 min, P = .24) or in compliance of the respiratory system (41 ± 11 mL/cm H2O at baseline vs 40 ± 12 mL/cm H2O at 15 min and 40 ± 12 mL/cm H2O at 60 min, P = .32). The bench study showed that auto-triggering by the ventilator when disconnecting from the expiratory circuit kept the tracheal pressure above PEEP for at least 3 s with pressure controlled ventilation. This study showed that a short disconnection of the expiratory ventilator circuit from the ventilator during filter exchange was not associated with any significant deterioration in lung function 15 and 60 min later. This result may be explained by auto-triggering of the ventilator with high inspiratory flows during the filter exchange, maintaining airway pressure.

  17. 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.

  18. Bench evaluation of 7 home-care ventilators.

    PubMed

    Blakeman, Thomas C; Rodriquez, Dario; Hanseman, Dennis; Branson, Richard D

    2011-11-01

    Portable ventilators continue to decrease in size while increasing in performance. We bench-tested the triggering, battery duration, and tidal volume (V(T)) of 7 portable ventilators: LTV 1000, LTV 1200, Puritan Bennett 540, Trilogy, Vela, iVent 101, and HT50. We tested triggering with a modified dual-chamber test lung to simulate spontaneous breathing with weak, normal, and strong inspiratory effort. We measured battery duration by fully charging the battery and operating the ventilator with a V(T) of 500 mL, a respiratory rate of 20 breaths/min, and PEEP of 5 cm H(2)O until breath-delivery ceased. We tested V(T) accuracy with pediatric ventilation scenarios (V(T) 50 mL or 100 mL, respiratory rate 50 breaths/min, inspiratory time 0.3 s, and PEEP 5 cm H(2)O) and an adult ventilation scenario (V(T) 400 mL, respiratory rate 30 breaths/min, inspiratory time 0.5 s, and PEEP 5 cm H(2)O). We measured and analyzed airway pressure, volume, and flow signals. At the adult settings the measured V(T) range was 362-426 mL. On the pediatric settings the measured V(T) range was 51-182 mL at the set V(T) of 50 mL, and 90-141 mL at the set V(T) of 100 mL. The V(T) delivered by the Vela at both the 50 mL and 100 mL, and by the HT50 at 100 mL, did not meet the American Society for Testing and Materials standard for V(T) accuracy. Triggering response and battery duration ranged widely among the tested ventilators. There was wide variability in battery duration and triggering sensitivity. Five of the ventilators performed adequately in V(T) delivery across several settings. The combination of high respiratory rate and low V(T) presented problems for 2 of the ventilators.

  19. Driving pressure and survival in the acute respiratory distress syndrome.

    PubMed

    Amato, Marcelo B P; Meade, Maureen O; Slutsky, Arthur S; Brochard, Laurent; Costa, Eduardo L V; Schoenfeld, David A; Stewart, Thomas E; Briel, Matthias; Talmor, Daniel; Mercat, Alain; Richard, Jean-Christophe M; Carvalho, Carlos R R; Brower, Roy G

    2015-02-19

    Mechanical-ventilation strategies that use lower end-inspiratory (plateau) airway pressures, lower tidal volumes (VT), and higher positive end-expiratory pressures (PEEPs) can improve survival in patients with the acute respiratory distress syndrome (ARDS), but the relative importance of each of these components is uncertain. Because respiratory-system compliance (CRS) is strongly related to the volume of aerated remaining functional lung during disease (termed functional lung size), we hypothesized that driving pressure (ΔP=VT/CRS), in which VT is intrinsically normalized to functional lung size (instead of predicted lung size in healthy persons), would be an index more strongly associated with survival than VT or PEEP in patients who are not actively breathing. Using a statistical tool known as multilevel mediation analysis to analyze individual data from 3562 patients with ARDS enrolled in nine previously reported randomized trials, we examined ΔP as an independent variable associated with survival. In the mediation analysis, we estimated the isolated effects of changes in ΔP resulting from randomized ventilator settings while minimizing confounding due to the baseline severity of lung disease. Among ventilation variables, ΔP was most strongly associated with survival. A 1-SD increment in ΔP (approximately 7 cm of water) was associated with increased mortality (relative risk, 1.41; 95% confidence interval [CI], 1.31 to 1.51; P<0.001), even in patients receiving "protective" plateau pressures and VT (relative risk, 1.36; 95% CI, 1.17 to 1.58; P<0.001). Individual changes in VT or PEEP after randomization were not independently associated with survival; they were associated only if they were among the changes that led to reductions in ΔP (mediation effects of ΔP, P=0.004 and P=0.001, respectively). We found that ΔP was the ventilation variable that best stratified risk. Decreases in ΔP owing to changes in ventilator settings were strongly associated with

  20. Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications: LAS VEGAS - an observational study in 29 countries.

    PubMed

    2017-08-01

    Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. This was a prospective international 1-week observational study using the 'Assess Respiratory Risk in Surgical Patients in Catalonia risk score' (ARISCAT score) for PPC for risk stratification. Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome. The study was registered at Clinicaltrials

  1. Management and outcome of mechanically ventilated patients after cardiac arrest.

    PubMed

    Sutherasan, Yuda; Peñuelas, Oscar; Muriel, Alfonso; Vargas, Maria; Frutos-Vivar, Fernando; Brunetti, Iole; Raymondos, Konstantinos; D'Antini, Davide; Nielsen, Niklas; Ferguson, Niall D; Böttiger, Bernd W; Thille, Arnaud W; Davies, Andrew R; Hurtado, Javier; Rios, Fernando; Apezteguía, Carlos; Violi, Damian A; Cakar, Nahit; González, Marco; Du, Bin; Kuiper, Michael A; Soares, Marco Antonio; Koh, Younsuck; Moreno, Rui P; Amin, Pravin; Tomicic, Vinko; Soto, Luis; Bülow, Hans-Henrik; Anzueto, Antonio; Esteban, Andrés; Pelosi, Paolo

    2015-05-08

    The aim of this study was to describe and compare the changes in ventilator management and complications over time, as well as variables associated with 28-day hospital mortality in patients receiving mechanical ventilation (MV) after cardiac arrest. We performed a secondary analysis of three prospective, observational multicenter studies conducted in 1998, 2004 and 2010 in 927 ICUs from 40 countries. We screened 18,302 patients receiving MV for more than 12 hours during a one-month-period. We included 812 patients receiving MV after cardiac arrest. We collected data on demographics, daily ventilator settings, complications during ventilation and outcomes. Multivariate logistic regression analysis was performed to calculate odds ratios, determining which variables within 24 hours of hospital admission were associated with 28-day hospital mortality and occurrence of acute respiratory distress syndrome (ARDS) and pneumonia acquired during ICU stay at 48 hours after admission. Among 812 patients, 100 were included from 1998, 239 from 2004 and 473 from 2010. Ventilatory management changed over time, with decreased tidal volumes (VT) (1998: mean 8.9 (standard deviation (SD) 2) ml/kg actual body weight (ABW), 2010: 6.7 (SD 2) ml/kg ABW; 2004: 9 (SD 2.3) ml/kg predicted body weight (PBW), 2010: 7.95 (SD 1.7) ml/kg PBW) and increased positive end-expiratory pressure (PEEP) (1998: mean 3.5 (SD 3), 2010: 6.5 (SD 3); P <0.001). Patients included from 2010 had more sepsis, cardiovascular dysfunction and neurological failure, but 28-day hospital mortality was similar over time (52% in 1998, 57% in 2004 and 52% in 2010). Variables independently associated with 28-day hospital mortality were: older age, PaO2 <60 mmHg, cardiovascular dysfunction and less use of sedative agents. Higher VT, and plateau pressure with lower PEEP were associated with occurrence of ARDS and pneumonia acquired during ICU stay. Protective mechanical ventilation with lower VT and higher PEEP is more

  2. Feasibility and safety of low-flow extracorporeal carbon dioxide removal to facilitate ultra-protective ventilation in patients with moderate acute respiratory distress sindrome.

    PubMed

    Fanelli, Vito; Ranieri, Marco V; Mancebo, Jordi; Moerer, Onnen; Quintel, Michael; Morley, Scott; Moran, Indalecio; Parrilla, Francisco; Costamagna, Andrea; Gaudiosi, Marco; Combes, Alain

    2016-02-10

    Mechanical ventilation with a tidal volume (VT) of 6 mL/kg/predicted body weight (PBW), to maintain plateau pressure (Pplat) lower than 30 cmH2O, does not completely avoid the risk of ventilator induced lung injury (VILI). The aim of this study was to evaluate safety and feasibility of a ventilation strategy consisting of very low VT combined with extracorporeal carbon dioxide removal (ECCO2R). In fifteen patients with moderate ARDS, VT was reduced from baseline to 4 mL/kg PBW while PEEP was increased to target a plateau pressure--(Pplat) between 23 and 25 cmH2O. Low-flow ECCO2R was initiated when respiratory acidosis developed (pH < 7.25, PaCO2 > 60 mmHg). Ventilation parameters (VT, respiratory rate, PEEP), respiratory compliance (CRS), driving pressure (DeltaP = VT/CRS), arterial blood gases, and ECCO2R system operational characteristics were collected during the period of ultra-protective ventilation. Patients were weaned from ECCO2R when PaO2/FiO2 was higher than 200 and could tolerate conventional ventilation settings. Complications, mortality at day 28, need for prone positioning and extracorporeal membrane oxygenation, and data on weaning from both MV and ECCO2R were also collected. During the 2 h run in phase, VT reduction from baseline (6.2 mL/kg PBW) to approximately 4 mL/kg PBW caused respiratory acidosis (pH < 7.25) in all fifteen patients. At steady state, ECCO2R with an average blood flow of 435 mL/min and sweep gas flow of 10 L/min was effective at correcting pH and PaCO2 to within 10 % of baseline values. PEEP values tended to increase at VT of 4 mL/kg from 12.2 to 14.5 cmH2O, but this change was not statistically significant. Driving pressure was significantly reduced during the first two days compared to baseline (from 13.9 to 11.6 cmH2O; p < 0.05) and there were no significant differences in the values of respiratory system compliance. Rescue therapies for life threatening hypoxemia such as prone position and ECMO were necessary in four and two

  3. Effects of Xuanbai Chengqi decoction on lung compliance for patients with exogenous pulmonary acute respiratory distress syndrome

    PubMed Central

    Mao, Zhengrong; Wang, Haifeng

    2016-01-01

    Objective To observe the effects of Xuanbai Chengqi decoction on lung compliance for patients with exogenous pulmonary acute respiratory distress syndrome. Subjects and methods A total of 53 patients with exogenous pulmonary acute respiratory distress syndrome, who were admitted to the intensive care unit of the First Affiliated Hospital of Henan University of Traditional Chinese Medicine from March 2009 to February 2013, were selected. They were randomly divided into the treatment group (25 cases) and the control group (28 cases). Both the groups were treated with conventional treatment and lung-protective ventilation strategy; apart from these, enema therapy with Xuanbai Chengqi decoction was given to the treatment group. Meanwhile, static lung compliance, dynamic lung compliance, peak airway pressure, plateau pressure, and positive end-expiratory pressure (PEEP) for patients in both the groups were observed and recorded at 24, 48, and 72 hours after the drug was used. Moreover, variations in the duration of parenteral nutrition, incidence rate of complications, and case fatality rate in patients after treatment were recorded. Results For patients in the treatment group, at 48 and 72 hours after treatment, the static lung compliance and dynamic lung compliance were significantly higher than those in the control group, while plateau pressure, peak airway pressure, and PEEP were significantly lower than those before treatment. At the same time, PEEP for patients in the treatment group at 72 hours after treatment was remarkably lower than that in the control group, showing significant difference (P<0.05). The duration of parenteral nutrition in the treatment group was significantly shorter than that in the control group (P<0.05). Both the incidence rate and the fatality rate of complications, such as abdominal distension and ventilator-associated pneumonia, for patients in the treatment group were distinctly smaller than those in the control group (P<0

  4. 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

  5. Effects of large volume, ice-cold intravenous fluid infusion on respiratory function in cardiac arrest survivors.

    PubMed

    Jacobshagen, Claudius; Pax, Anja; Unsöld, Bernhard W; Seidler, Tim; Schmidt-Schweda, Stephan; Hasenfuss, Gerd; Maier, Lars S

    2009-11-01

    International guidelines for cardiopulmonary resuscitation recommend mild hypothermia (32-34 degrees C) for 12-24h in comatose survivors of cardiac arrest. To induce therapeutic hypothermia a variety of external and intravascular cooling devices are available. A cheap and effective method for inducing hypothermia is the infusion of large volume, ice-cold intravenous fluid. There are concerns regarding the effects of rapid infusion of large volumes of fluid on respiratory function in cardiac arrest survivors. We have retrospectively studied the effects of high volume cold fluid infusion on respiratory function in 52 resuscitated cardiac arrest patients. The target temperature of 32-34 degrees C was achieved after 4.1+/-0.5h (cooling rate 0.48 degrees C/h). During this period 3427+/-210 mL ice-cold fluid was infused. Despite significantly reduced LV-function (EF 35.8+/-2.2%) the respiratory status of these patients did not deteriorate significantly. On intensive care unit admission the mean PaO(2) was 231.4+/-20.6 mmHg at a F(i)O(2) of 0.82+/-0.03 (PaO(2)/F(i)O(2)=290.0+/-24.1) and a PEEP level of 7.14+/-0.31 mbar. Until reaching the target temperature of PEEP level (7.23+/-0.36 mbar). Under these conditions the PaO(2)/F(i)O(2) ratio slightly decreased to 247.5+/-18.5 (P=0.0893). Continuing the saline infusion to achieve a body temperature of 33 degrees C, the F(i)O(2) could be further reduced with unchanged PEEP. The infusion of large volume, ice-cold fluid is an effective and inexpensive method for inducing therapeutic hypothermia. Resuscitation from cardiac arrest is associated with a deterioration in respiratory function. The infusion of large volumes of cold fluid does not cause a statistically significant further deterioration in respiratory function. A larger, randomized and prospective study is required to assess the efficacy and safety of ice-cold fluid infusion for

  6. Maintaining end-expiratory transpulmonary pressure prevents worsening of ventilator-induced lung injury caused by chest wall constriction in surfactant-depleted rats

    PubMed Central

    Loring, Stephen H.; Pecchiari, Matteo; Valle, Patrizia Della; Monaco, Ario; Gentile, Guendalina; D'Angelo, Edgardo

    2014-01-01

    Objective To see whether in acute lung injury (ALI) 1) compression of the lungs caused by thoracoabdominal constriction degrades lung function and worsens ventilator-induced lung injury (VILI), and 2) maintaining end-expiratory transpulmonary pressure (Pl) by increasing positive end-expiratory pressure (PEEP) reduces the deleterious effects of chest wall constriction. Design Experimental study in rats. Setting Physiology laboratory. Interventions ALI was induced in 3 groups of 9 rats by saline lavage. Nine animals immediately sacrificed served as control group. Group L had lavage only, group LC had the chest wall constricted with an elastic binder, and group LCP had the same chest constriction but with PEEP raised to maintain end-expiratory Pl. After lavage, all groups were ventilated with the same pattern for 1½ hr. Measurements and Main Results Pl, measured with an esophageal balloon-catheter, lung volume changes, arterial blood gasses and pH were assessed during mechanical ventilation (MV). Lung wet-to-dry ratio (W/D), albumin, TNF-α, IL-1β, IL-6, IL-10, and MIP-2 in serum and bronchoalveolar lavage fluid (BALF), and serum E-selectin and von Willebrand Factor (vWF) were measured at the end of MV. Lavage caused hypoxemia and acidemia, increased lung resistance and elastance, and decreased end-expiratory lung volume. With prolonged MV, lung mechanics, hypoxemia, and W/D were significantly worse in group LC. Pro-inflammatory cytokines except E-selectin were elevated in serum and BALF in all groups, with significantly greater levels of TNF-α, IL-1β, and IL-6 in group LC, which also exhibited significantly worse bronchiolar injury and greater heterogeneity of airspace expansion at a fixed Pl than other groups. Conclusions Chest wall constriction in ALI reduces lung volume, worsens hypoxemia, and increases pulmonary edema, mechanical abnormalities, pro-inflammatory mediator release, and histological signs of VILI. Maintaining end-expiratory Pl at preconstriction

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

    PubMed Central

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

    2009-01-01

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

  8. Effect of Local Tidal Lung Strain on Inflammation in Normal and Lipopolysaccharide-Exposed Sheep

    PubMed Central

    Wellman, Tyler J.; Winkler, Tilo; Costa, Eduardo L.V.; Musch, Guido; Harris, R. Scott; Zheng, Hui; Venegas, Jose G.; Vidal Melo, Marcos F.

    2014-01-01

    Objective Regional tidal lung strain may trigger local inflammation during mechanical ventilation, particularly when additional inflammatory stimuli are present. However, it is unclear whether inflammation develops proportionally to tidal strain or only above a threshold. We aimed to: (1) assess the relationship between regional tidal strain and local inflammation in vivo during the early stages of lung injury in lungs with regional aeration heterogeneity comparable to that of humans; and (2) determine how this strain-inflammation relationship is affected by endotoxemia. Design Interventional animal study. Setting Experimental laboratory and positron emission tomography (PET) facility. Subjects Eighteen 2–4-month-old sheep. Interventions Three groups of sheep (n=6) were mechanically ventilated to the same plateau pressure (30–32 cmH2O) with High-Strain (VT=18.2±6.5 ml/kg, PEEP=0), High-Strain plus intravenous lipopolysaccharide (LPS) (VT=18.4±4.2 ml/kg, PEEP=0), or Low-Strain plus LPS (VT=8.1±0.2 ml/kg, PEEP=17±3 cmH2O). At baseline, we acquired respiratory-gated PET scans of inhaled 13NN to measure tidal strain from end-expiratory and end-inspiratory images in six regions of interest (ROIs). After 3 hours of mechanical ventilation, dynamic [18F]fluoro-2-deoxy-D-glucose (18F-FDG) scans were acquired to quantify metabolic activation, indicating local neutrophilic inflammation, in the same ROIs. Measurements and Main Results Baseline regional tidal strain had a significant effect on 18F-FDG net uptake rate Ki in High-Strain LPS (p=0.036) and on phosphorylation rate k3 in High-Strain (p=0.027) and High-Strain LPS (p=0.004). LPS exposure increased the k3-tidal strain slope 3-fold (p=0.009), without significant lung edema. The Low-Strain LPS group showed lower baseline regional tidal strain (0.33±0.17) than High-Strain (1.21±0.62; p<0.001) or High-Strain LPS (1.26±0.44; p<0.001), and lower k3 (p<0.001) and Ki (p<0.05) than High-Strain LPS. Conclusions Local

  9. 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.

  10. Effect of regional lung inflation on ventilation heterogeneity at different length scales during mechanical ventilation of normal sheep lungs.

    PubMed

    Wellman, Tyler J; Winkler, Tilo; Costa, Eduardo L V; Musch, Guido; Harris, R Scott; Venegas, Jose G; Vidal Melo, Marcos F

    2012-09-01

    Heterogeneous, small-airway diameters and alveolar derecruitment in poorly aerated regions of normal lungs could produce ventilation heterogeneity at those anatomic levels. We modeled the washout kinetics of (13)NN with positron emission tomography to examine how specific ventilation (sV) heterogeneity at different length scales is influenced by lung aeration. Three groups of anesthetized, supine sheep were studied: high tidal volume (Vt; 18.4 ± 4.2 ml/kg) and zero end-expiratory pressure (ZEEP) (n = 6); low Vt (9.2 ± 1.0 ml/kg) and ZEEP (n = 6); and low Vt (8.2 ± 0.2 ml/kg) and positive end-expiratory pressure (PEEP; 19 ± 1 cmH(2)O) (n = 4). We quantified fractional gas content with transmission scans, and sV with emission scans of infused (13)NN-saline. Voxel (13)NN-washout curves were fit with one- or two-compartment models to estimate sV. Total heterogeneity, measured as SD[log(10)(sV)], was divided into length-scale ranges by measuring changes in variance of log(10)(sV), resulting from progressive filtering of sV images. High-Vt ZEEP showed higher sV heterogeneity at <12- (P < 0.01), 12- to 36- (P < 0.01), and 36- to 60-mm (P < 0.05) length scales compared with low-Vt PEEP, with low-Vt ZEEP in between. Increased heterogeneity was associated with the emergence of low sV units in poorly aerated regions, with a high correlation (r = 0.95, P < 0.001) between total heterogeneity and the fraction of lung with slow washout. Regional mean fractional gas content was inversely correlated with regional sV heterogeneity at <12- (r = -0.67), 12- to 36- (r = -0.74), and >36-mm (r = -0.72) length scales (P < 0.001). We conclude that sV heterogeneity at length scales <60 mm increases in poorly aerated regions of mechanically ventilated normal lungs, likely due to heterogeneous small-airway narrowing and alveolar derecruitment. PEEP reduces sV heterogeneity by maintaining lung expansion and airway patency at those small length scales.

  11. Physiological Correlation of Airway Pressure and Transpulmonary Pressure Stress Index on Respiratory Mechanics in Acute Respiratory Failure

    PubMed Central

    Pan, Chun; Chen, Lu; Zhang, Yun-Hang; Liu, Wei; Urbino, Rosario; Ranieri, V Marco; Qiu, Hai-Bo; Yang, Yi

    2016-01-01

    Background: Stress index at post-recruitment maneuvers could be a method of positive end-expiratory pressure (PEEP) titration in acute respiratory distress syndrome (ARDS) patients. However, airway pressure (Paw) stress index may not reflect lung mechanics in the patients with high chest wall elastance. This study was to evaluate the Paw stress index on lung mechanics and the correlation between Paw stress index and transpulmonary pressure (PL) stress index in acute respiratory failure (ARF) patients. Methods: Twenty-four ARF patients with mechanical ventilation (MV) were consecutively recruited from July 2011 to April 2013 in Zhongda Hospital, Nanjing, China and Ospedale S. Giovanni Battista-Molinette Hospital, Turin, Italy. All patients underwent MV with volume control (tidal volume 6 ml/kg) for 20 min. PEEP was set according to the ARDSnet study protocol. The patients were divided into two groups according to the chest wall elastance/respiratory system elastance ratio. The high elastance group (H group, n = 14) had a ratio ≥30%, and the low elastance group (L group, n = 10) had a ratio <30%. Respiratory elastance, gas-exchange, Paw stress index, and PL stress index were measured. Student's t-test, regression analysis, and Bland–Altman analysis were used for statistical analysis. Results: Pneumonia was the major cause of respiratory failure (71.0%). Compared with the L group, PEEP was lower in the H group (5.7 ± 1.7 cmH2O vs. 9.0 ± 2.3 cmH2O, P < 0.01). Compared with the H group, lung elastance was higher (20.0 ± 7.8 cmH2O/L vs. 11.6 ± 3.6 cmH2O/L, P < 0.01), and stress was higher in the L group (7.0 ± 1.9 vs. 4.9 ± 1.9, P = 0.02). A linear relationship was observed between the Paw stress index and the PL stress index in H group (R2= 0.56, P < 0.01) and L group (R2= 0.85, P < 0.01). Conclusion: In the ARF patients with MV, Paw stress index can substitute for PL to guide ventilator settings. Trial Registration: ClinicalTrials.gov NCT02196870 (https

  12. Scorpion sting envenomation presenting with pulmonary edema in adults: a report of seven cases from Nepal.

    PubMed

    Bhadani, Umesh Kumar; Tripathi, Mukesh; Sharma, Sanjib; Pandey, Rajesh

    2006-01-01

    Scorpion sting is a common problem in villages of Eastern Nepal. The life-threatening complications of myocarditis and pulmonary edema is known in red scorpion in India but not reported in Nepal. This condition requires urgent attention and ICU care from few hours to days. Delay in recognition and the hypoxemia increase the morbidity and mortality. Illiteracy, ignorance, poverty, traditional faith healers trying treatment in remote areas, lack of transport in difficult terrains and the non availability of ventilation facility in nearby hospital, add to delay in appropriate treatment. Seven young adult patients admitted in a span of two years with history of scorpion sting presenting with pulmonary edema required ICU care. They were successfully managed with the positive pressure ventilation with PEEP, cardiac support with inotropes and fluid balance. Magnitude of problem, clinical presentation and management done is emphasized.

  13. Assessment of Severity of Ovine Smoke Inhalation Injury by Analysis of Computed Tomographic Scans

    DTIC Science & Technology

    2003-09-01

    H2O. Then, permit hypercapnia as long as pH 7.1 ● FIO2 : adjust to keep SpO2 91% and PaO2 60 mm Hg ● PEEP: no change until FIO2 100%, then...the utility of a chest radiograph score, the PaO2 / FIO2 ratio (PFR), the peak inspiratory pres- sure, and a bronchoscopic score in predicting survival...increase up to a maximum of 15 cm H2O, to keep SpO2 91% and PaO2 60 mm Hg ● Respiratory rate: adjust to keep pH 7.1, up to a maximum of 30 breaths

  14. Zinc oxide nanorod field effect transistor for long-time cellular force measurement

    PubMed Central

    Zong, Xianli; Zhu, Rong

    2017-01-01

    Mechanical forces generated by cells are known to influence a vast range of cellular functions ranging from receptor signaling and transcription to differentiation and proliferation. We report a novel measurement approach using zinc oxide nanorods as a peeping transducer to monitor dynamic mechanical behavior of cellular traction on surrounding substrate. We develop a ZnO nanorod field effect transistor (FET) as an ultrasensitive force sensor to realize long-time, unstained, and in-situ detection of cell cycle phases, including attachment, spread, and mitosis. Excellent biocompatibility and ultra-sensitivity of the biomechanical measurement is ensured by coating a parylene film on the FET sensor as a concealment, which provides complete electronic isolation between the sensor and cell. With unique features of ultra-sensitivity, label-free, easy handling, and good biocompatibility, the force sensor allows feasible for tracking cellular dynamics in physiological contexts and understanding their contribution to biological processes. PMID:28272551

  15. Amygdalar vocalization pathways in the squirrel monkey.

    PubMed

    Jürgens, U

    1982-06-10

    In 22 squirrel monkeys (Saimiri sciureus) vocalization-eliciting electrodes were implanted into the amygdala and along the trajectory of the stria terminalis. Then, lesions were placed in the stria terminalis, its bed nucleus, the ventral amygdalofugal pathway and several di- and mesencephalic structures in order to find out the pathways along which the amygdala exerts its vocalization-controlling influence. It was found that different call types are controlled by different pathways. Purring and chattering calls, which express a self-confident, challenging attitude and an attempt to recruit fellow-combatants in intra-specific mobbing, respectively, are controlled via the stria terminalis; alarm peep and groaning calls, in contrast, which indicate flight motivation and resentment, respectively, are triggered via the ventral amygdalofugal fibre bundle. Both pathways traverse the dorsolateral and dorsomedial hypothalamus, respectively, and unite in the periaqueductal grey of the midbrain.

  16. Pneumonia due to aspiration of povidine iodine after induction of general anesthesia -A case report-

    PubMed Central

    Ahn, Byung Ryang

    2011-01-01

    Aspiration pneumonia is usually caused by aspiration of gastric contents during anesthesia. It causes severe pulmonary complications. Povidone iodine was used widely as an oral antiseptic. Although povidone iodine is thought to be a safe and effective antiseptic, severe complications from its aspiration may occur. We present a case of pneumonia secondary to aspiration of povidone iodine in a 16 year old female patient who underwent orofacial surgery. Aspiration pneumonia must be treated immediately. Mechanical ventilation with PEEP and periodical bronchial toilet with fiberoptic bronchoscopy were carried in the operating room and ICU. Bronchodilators, antibiotics, steroids and diuretics were also used to treat pneumonia. The patient was treated successfully without any complication. PMID:22025949

  17. [Mobile intensive-care-unit for transportation of premature and newborn babies at risc (author's transl)].

    PubMed

    Wille, L; Obladen, M; Schlunk, P; Weisser, J

    1975-02-01

    This is a technical report on a specially equipped ambulance for transportation of high-risk, seriously ill neonates. A mobile neonatal intensive-care-unit operating independently of the car utilized an Ohio-transport-incubator with 12V-DC portable power pak and collapsible stand, battery-operated ECG-monitor with optical and acoustical signal, a ECG-monitor with optical and acoustical signal, a battery-operated infusion pump, a Bird-respirator mark 8 with oxygen-blender, nebulizer and infant circuit with modification for PEEP as well as additional accessories. Ambulance-duty service is guaranteed by the German Red Cross (DRK) to facilitate transfer at any time, while skilled personal (physician, nurse) of the intensive care ward in on 24 hs call.

  18. Analysis of regional compliance in a porcine model of acute lung injury.

    PubMed

    Czaplik, Michael; Biener, Ingeborg; Dembinski, Rolf; Pelosi, Paolo; Soodt, Thomas; Schroeder, Wolfgang; Leonhardt, Steffen; Marx, Gernot; Rossaint, Rolf; Bickenbach, Johannes

    2012-10-15

    Lung protective ventilation in acute lung injury (ALI) focuses on using low tidal volumes and adequate levels of positive end-expiratory pressure (PEEP). Identifying optimal pressure is difficult because pressure-volume (PV) relations differ regionally. Precise analysis demands local measurements of pressures and related alveolar morphologies. In a porcine model of surfactant depletion (n=24), we combined measuring static pressures with endoscopic microscopy and electrical impedance tomography (EIT) to examine regional PV loops and morphologic heterogeneities between healthy (control group; CON) and ALI lungs ventilated with low (LVT) or high tidal volumes (HVT). Quantification included indices for microscopy (Volume Air Index (VAI), Heterogeneity and Circularity Index), EIT analysis and calculation of regional compliances due to generated PV loops. We found that: (1) VAI decreased in lower lobe after ALI, (2) electrical impedance decreased in dorsal regions and (3) PV loops differed regionally. Further studies should prove the potentials of these techniques on individual respiratory settings and clinical outcome.

  19. Thoracic Block Technique Associated with Positive End-Expiratory Pressure in Reversing Atelectasis

    PubMed Central

    Pereira, Luciana Carnevalli; de Souza Netto, Ana Paula; da Silva, Fernanda Cordeiro; Pereira, Silvana Alves; Moran, Cristiane Aparecida

    2015-01-01

    A preschool four-year-old male patient had been admitted to the Mandaqui Hospital with a diagnosis of lobar pneumonia, pleural effusion, and right lung atelectasis. Treatment consisted of antibiotics and physiotherapy sessions, using a technique described in the literature as Insufflation Technique to Reverse Atelectasis (ITRA), which consists of a thoracic block of healthy lung tissue, leaving only the atelectasis area free, associated with the use of invasive or noninvasive mechanical ventilation with positive airway pressure for reversal of atelectasis. Two physiotherapy sessions were conducted daily. The sessions lasted 20 minutes and were fractionated into four series of five minutes each. Each series bilateral thoracic block was performed for 20 seconds with a pause lasting for the same time. Associated with the thoracic block, a continuous positive airways pressure was used using a facial mask and 7 cm H2O PEEP provided via CPAP. Conclusion. ITRA technique was effective in reversing atelectasis in this patient. PMID:25883824

  20. [Right ventricular function in ARDS and mechanical respiration].

    PubMed

    Engelmann, L

    2004-10-01

    The right ventricle is the stepchild of intensive care medicine. In diseases of the lung mainly when the relationship between ventilation and perfusion is disturbed, assisted respiration with positive end-expiratory pressure (PEEP) is essential to improve oxygenation. The serious damage to the lung parenchyma as seen in adult (acute) respiratory distress syndrome (ARDS) and pneumonia has considerable consequences for cardiac function. Whereas left ventricular function remains almost completely unaffected well into late stages of the disease, the right ventricle is subjected early to stress from the underlying disease and mechanical ventilation. The effects of therapeutic measures aimed at maintaining oxygenation and ventilation partially have negative consequences for right ventricular function and encourage the development of acute cor pulmonale. They can be the cause of right-sided heart failure.

  1. Science and evidence: separating fact from fiction.

    PubMed

    Hess, Dean R

    2013-10-01

    Evidence-based medicine (EBM) is the integration of individual clinical expertise with the best available research evidence from systematic research and the patient's values and expectations. A hierarchy of evidence can be used to assess the strength upon which clinical decisions are made. The efficient approach to finding the best evidence is to identify systematic reviews or evidence-based clinical practice guidelines. Respiratory therapies that evidence supports include noninvasive ventilation for appropriately selected patients, lung-protective ventilation, and ventilator discontinuation protocols. Evidence does not support use of weaning parameters, albuterol for ARDS, and high frequency oscillatory ventilation for adults. Therapy with equivocal evidence includes airway clearance, selection of an aerosol delivery device, and PEEP for ARDS. Although all tenets of EBM are not universally accepted, the principles of EBM nonetheless provide a valuable approach to respiratory care practice.

  2. [Concepts and monitoring of pulmonary mechanic in patients under ventilatory support in intensive care unit].

    PubMed

    Faustino, Eduardo Antonio

    2007-06-01

    In mechanical ventilation, invasive and noninvasive, the knowledge of respiratory mechanic physiology is indispensable to take decisions and into the efficient management of modern ventilators. Monitoring of pulmonary mechanic parameters is been recommended from all the review works and clinical research. The objective of this study was review concepts of pulmonary mechanic and the methods used to obtain measures in the bed side, preparing a rational sequence to obtain this data. It was obtained bibliographic review through data bank LILACS, MedLine and PubMed, from the last ten years. This review approaches parameters of resistance, pulmonary compliance and intrinsic PEEP as primordial into comprehension of acute respiratory failure and mechanic ventilatory support, mainly in acute respiratory distress syndrome (ARDS) and in chronic obstructive pulmonary disease (COPD). Monitoring pulmonary mechanics in patients under mechanical ventilation in intensive care units gives relevant informations and should be implemented in a rational and systematic way.

  3. Regional distribution of lung compliance by image analysis of computed tomograms.

    PubMed

    Perchiazzi, Gaetano; Rylander, Christian; Derosa, Savino; Pellegrini, Mariangela; Pitagora, Loredana; Polieri, Debora; Vena, Antonio; Tannoia, Angela; Fiore, Tommaso; Hedenstierna, Göran

    2014-09-15

    Computed tomography (CT) can yield quantitative information about volume distribution in the lung. By combining information provided by CT and respiratory mechanics, this study aims at quantifying regional lung compliance (CL) and its distribution and homogeneity in mechanically ventilated pigs. The animals underwent inspiratory hold maneuvers at 12 lung volumes with simultaneous CT exposure at two end-expiratory pressure levels and before and after acute lung injury (ALI) by oleic acid administration. CL and the sum of positive voxel compliances from CT were linearly correlated; negative compliance areas were found. A remarkably heterogeneous distribution of voxel compliance was found in the injured lungs. As the lung inflation increased, the homogeneity increased in healthy lungs but decreased in injured lungs. Image analysis brought novel findings regarding spatial homogeneity of compliance, which increases in ALI but not in healthy lungs by applying PEEP after a recruitment maneuver.

  4. Post- Thyroidectomy Haematoma Causing Severe Supraglottic Oedema and Pulmonary Oedema - A Case Report

    PubMed Central

    Pujari, Vinayak Seenappa; Anandaswamy, Tejesh C; Vig, Saurabh

    2014-01-01

    Large, long standing goiters present multiple challenges to anaesthesiologist. Post thyroidectomy haematoma is a rare but life threatening complication of thyroid surgery leading to airway obstruction. We report a case of huge goiter that underwent near total thyroidectomy and developed post thyroidectomy haematoma. Within no time it resulted in near fatal airway obstruction, pulmonary oedema and cardiac arrest. The haematoma was evacuated immediately and patient was resuscitated successfully. Pulmonary oedema was further worsened by subsequent aggressive fluid resuscitation. She was electively ventilated with PEEP and was extubated after five days. Except for right vocal cord palsy her postoperative stay was uneventful. This is unique case where a post thyoidectomy haematoma has resulted in fatal supraglottic oedema and pulmonary oedema. Early recognition, immediate intubation and evacuation of haematoma are the key to manage this complication. We highlight on the pathophysiology of haematoma and discuss the strategies to prevent similar events in future. PMID:25300409

  5. Airway closure, atelectasis and gas exchange during anaesthesia.

    PubMed

    Hedenstierna, G

    2002-05-01

    Pulmonary gas exchange is regularly impaired during general anaesthesia with mechanical ventilation. This results in decreased oxygenation of blood. Major causes are collapse of lung tissue (atelectasis) and airway closure. Collapsed lung tissue is present in 90% of all subjects, both during spontaneous breathing and after muscle paralysis, and whether intravenous or inhalational anaesthetics are used. Airway closure is also common and increases in magnitude with increasing age of the patient. There are correlation between the amount of atelectasis and pulmonary shunt and between airway closure and perfusion of poorly ventilated lung regions (low VA/Q). Atelectasis and airway closure explain as much as 74% of gas exchange impairment in routine anaesthesia. A major cause of atelectasis is the pre-oxygenation during induction of anaesthesia. Lowering the inspired O2 concentration to 80% suffices to avoid almost all atelectasis. Airway closure and low VA/Q can only be prevented by raising the FRC level by PEEP or by other means.

  6. [Two cases of chronic atelectasis that improved through use of nasal continuous positive pressure].

    PubMed

    Tsuchiya, Michiko; Katsuki, Yuko; Enokibori, Toru; Ninomiya, Kiyoshi; Fujimura, Naoki

    2007-06-01

    We observed improvements in two cases of chronic atelectasis through use of nasal continuous positive airway pressure (nCPAP). Case 1 suffered from middle lobe syndrome accompanied by chronic atelectasis resistant to medical treatment. Case 2 suffered from respiratory failure caused by chronic atelectasis and airway infection complications thereof following a total pneumonectomy and post-pneumonectomy syndrome. The patient was placed on artificial ventilation, and atelectasis was improved by maintaining PEEP and airflow to the atelectatic region. Following extubation we obtained good pneumatization using nCPAP. nCPAP has been reported as effective not only in cases of sleep apnea, but also for cardiogenic pulmonary edema and post-operative atelectasis; we believe it holds great promise for chronic atelectasis as well.

  7. Thoracic block technique associated with positive end-expiratory pressure in reversing atelectasis.

    PubMed

    Pereira, Luciana Carnevalli; de Souza Netto, Ana Paula; da Silva, Fernanda Cordeiro; Pereira, Silvana Alves; Moran, Cristiane Aparecida

    2015-01-01

    A preschool four-year-old male patient had been admitted to the Mandaqui Hospital with a diagnosis of lobar pneumonia, pleural effusion, and right lung atelectasis. Treatment consisted of antibiotics and physiotherapy sessions, using a technique described in the literature as Insufflation Technique to Reverse Atelectasis (ITRA), which consists of a thoracic block of healthy lung tissue, leaving only the atelectasis area free, associated with the use of invasive or noninvasive mechanical ventilation with positive airway pressure for reversal of atelectasis. Two physiotherapy sessions were conducted daily. The sessions lasted 20 minutes and were fractionated into four series of five minutes each. Each series bilateral thoracic block was performed for 20 seconds with a pause lasting for the same time. Associated with the thoracic block, a continuous positive airways pressure was used using a facial mask and 7 cm H2O PEEP provided via CPAP. Conclusion. ITRA technique was effective in reversing atelectasis in this patient.

  8. Lung imaging in rodents using dual energy micro-CT

    NASA Astrophysics Data System (ADS)

    Badea, C. T.; Guo, X.; Clark, D.; Johnston, S. M.; Marshall, C.; Piantadosi, C.

    2012-03-01

    Dual energy CT imaging is expected to play a major role in the diagnostic arena as it provides material decomposition on an elemental basis. The purpose of this work is to investigate the use of dual energy micro-CT for the estimation of vascular, tissue, and air fractions in rodent lungs using a post-reconstruction three-material decomposition method. We have tested our method using both simulations and experimental work. Using simulations, we have estimated the accuracy limits of the decomposition for realistic micro-CT noise levels. Next, we performed experiments involving ex vivo lung imaging in which intact lungs were carefully removed from the thorax, were injected with an iodine-based contrast agent and inflated with air at different volume levels. Finally, we performed in vivo imaging studies in (n=5) C57BL/6 mice using fast prospective respiratory gating in endinspiration and end-expiration for three different levels of positive end-expiratory pressure (PEEP). Prior to imaging, mice were injected with a liposomal blood pool contrast agent. The mean accuracy values were for Air (95.5%), Blood (96%), and Tissue (92.4%). The absolute accuracy in determining all fraction materials was 94.6%. The minimum difference that we could detect in material fractions was 15%. As expected, an increase in PEEP levels for the living mouse resulted in statistically significant increases in air fractions at end-expiration, but no significant changes in end-inspiration. Our method has applicability in preclinical pulmonary studies where various physiological changes can occur as a result of genetic changes, lung disease, or drug effects.

  9. How Mechanical Ventilation Measurement, Cutoff and Duration Affect Rapid Shallow Breathing Index Accuracy: A Randomized Trial

    PubMed Central

    Goncalves, Elaine Cristina; Lago, Alessandra Fabiane; Silva, Elaine Caetano; de Almeida, Marcelo Barros; Basile-Filho, Anibal; Gastaldi, Ada Clarice

    2017-01-01

    Background Decreased accuracy of the rapid shallow breathing index (RSBI) can stem from 1) the method used to obtain this index, 2) duration of mechanical ventilation (MV), and 3) the established cutoff point. The objective was to evaluate the values of RSBI determined by three different methods, using distinct MV times and cutoff points. Methods This prospective study included 40 subjects. Before extubation, three different methods were employed to measure RSBI: pressure support ventilator (PSV) (PSV = 5 - 8 cm H2O; positive end-expiratory pressure (PEEP) = 5 cm H2O) (RSBI_MIN), automatic tube compensation (ATC) (PSV = 0, PEEP = 5 cm H2O, and 100% tube compensation) (RSBI_ATC), and disconnected MV (RSBI_SP). The results were analyzed according to the MV period (less than or over 72 h) and to the outcome of extubation (< 72 h, successful and failed; > 72 h successful and failed). The accuracy of each method was determined at different cutoff points (105, 78, and 50 cycles/min/L). Results The RSBI_MIN, RSBI_ATC, and RSBI_SP values in the group < 72 h were 38 ± 18, 45 ± 26 and 55 ± 22; in the group > 72 h, RSBI_SP value was higher than those of RSBI_ATC and RSBI_MIN (78 ± 29, 51 ± 19 and 39 ± 14) (P < 0.001). For patients with MV > 72 h who failed in removing MV, the RSBI_SP was higher (93 ± 28, 58 ± 18 and 41 ± 10) (P < 0.000), with greater accuracy at cutoff of 78. Conclusion RSBI_SP associated with cutoff point < 78 cycles/min/L seems to be the best strategy to identify failed extubation in subjects with MV for over 72 h. PMID:28270888

  10. Use of Bioimpedance to Assess Changes in Hemodynamics During Acute Administration of CPAP

    PubMed Central

    Digby, Genevieve C.; Driver, Helen S.; Fitzpatrick, Michael; Ropchan, Glorianne; Parker, Christopher M.

    2011-01-01

    Background Attempts to investigate the mechanisms by which continuous positive airway pressure (CPAP) therapy improves heart function in patients with obstructive sleep apnea (OSA) have been limited by the lack of non-invasive methods to assess cardiac performance. We used transthoracic electrical bioimpedance (TEB) to assess acute hemodynamic changes including heart rate (HR), stroke volume (SV), cardiac output (CO) and cardiac index (CI) during PAP titration in (1) post-operative cardiac surgery patients, (2) patients with severe OSA, and (3) normal healthy volunteers. Methods Post-operative cardiac surgery patients were studied via TEB and pulmonary artery catheter (PAC) during acute titration of positive end-expiratory pressure (PEEP) while mechanically ventilated. Patients with severe OSA were studied non-invasively by TEB during acute CPAP titration in supine stage 2 sleep, and normal subjects while awake and recumbent. Results In post-operative cardiac surgery patients (n = 3), increasing PEEP to 18 cmH2O significantly reduced SV and CI relative to baseline. There was no difference between TEB and PAC in terms of ability to assess variations in hemodynamic parameters. In patients with severe OSA (n = 3), CPAP titration to optimal pressure to alleviate obstructive apneas reduced HR, SV, CO and CI significantly compared to without CPAP. In three healthy subjects, maximal tolerated CPAP reduced SV and CO significantly compared to baseline. Conclusions Acute administration of CPAP causes a decrease in CO and CI, apparently a consequence of a reduction in SV. TEB appears to be an accurate and reproducible non-invasive method of detecting changes in hemodynamics.

  11. Driving pressure and mechanical power: new targets for VILI prevention.

    PubMed

    Tonetti, Tommaso; Vasques, Francesco; Rapetti, Francesca; Maiolo, Giorgia; Collino, Francesca; Romitti, Federica; Camporota, Luigi; Cressoni, Massimo; Cadringher, Paolo; Quintel, Michael; Gattinoni, Luciano

    2017-07-01

    Several factors have been recognized as possible triggers of ventilator-induced lung injury (VILI). The first is pressure (thus the 'barotrauma'), then the volume (hence the 'volutrauma'), finally the cyclic opening-closing of the lung units ('atelectrauma'). Less attention has been paid to the respiratory rate and the flow, although both theoretical considerations and experimental evidence attribute them a significant role in the generation of VILI. The initial injury to the lung parenchyma is necessarily mechanical and it could manifest as an unphysiological distortion of the extracellular matrix and/or as micro-fractures in the hyaluronan, likely the most fragile polymer embedded in the matrix. The order of magnitude of the energy required to break a molecular bond between the hyaluronan and the associated protein is 1.12×10(-16) Joules (J), 70-90% higher than the average energy delivered by a single breath of 1L assuming a lung elastance of 10 cmH2O/L (0.5 J). With a normal statistical distribution of the bond strength some polymers will be exposed each cycle to an energy large enough to rupture. Both the extracellular matrix distortion and the polymer fractures lead to inflammatory increase of capillary permeability with edema if a pulmonary blood flow is sufficient. The mediation analysis of higher vs. lower tidal volume and PEEP studies suggests that the driving pressure, more than tidal volume, is the best predictor of VILI, as inferred by increased mortality. This is not surprising, as both tidal volume and respiratory system elastance (resulting in driving pressure) may independently contribute to the mortality. For the same elastance driving pressure is a predictor similar to plateau pressure or tidal volume. Driving pressure is one of the components of the mechanical power, which also includes respiratory rate, flow and PEEP. Finding the threshold for mechanical power would greatly simplify assessment and prevention of VILI.

  12. The effect of low level laser therapy on ventilator-induced lung injury in mice (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Szabari, Margit V.; Miller, Alyssa J.; Hariri, Lida P.; Hamblin, Michael R.; Musch, Guido; Stroh, Helene; Suter, Melissa J.

    2016-03-01

    Although mechanical ventilation (MV) is necessary to support gas exchange in critically ill patients, it can contribute to the development of lung injury and multiple organ dysfunction. It is known that high tidal volume (Vt) MV can cause ventilator-induced lung injury (VILI) in healthy lungs and increase the mortality of patients with Acute Respiratory Distress Syndrome. Low level laser therapy (LLLT) has demonstrated to have anti-inflammatory effects. We investigated whether LLLT could alleviate inflammation from injurious MV in mice. Adult mice were assigned to 2 groups: VILI+LLLT group (3 h of injurious MV: Vt=25-30 ml/kg, respiratory rate (RR)=50/min, positive end-expiratory pressure (PEEP)=0 cmH20, followed by 3 h of protective MV: Vt=9 ml/kg, RR=140/min, PEEP=2 cmH20) and VILI+no LLLT group. LLLT was applied during the first 30 min of the MV (810 nm LED system, 5 J/cm2, 1 cm above the chest). Respiratory impedance was measured in vivo with forced oscillation technique and lung mechanics were calculated by fitting the constant phase model. At the end of the MV, bronchoalveolar lavage (BAL) was performed and inflammatory cells counted. Lungs were removed en-bloc and fixed for histological evaluation. We hypothesize that LLLT can reduce lung injury and inflammation from VILI. This therapy could be translated into clinical practice, where it can potentially improve outcomes in patients requiring mechanical ventilation in the operating room or in the intensive care units.

  13. Hyperpolarized Gas Diffusion MRI for the Study of Atelectasis and Acute Respiratory Distress Syndrome

    PubMed Central

    Cereda, Maurizio; Xin, Yi; Kadlecek, Stephen; Hamedani, Hooman; Rajaei, Jennia; Clapp, Justin; Rizi, Rahim R.

    2014-01-01

    Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury (VALI), which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of CT, PET, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized gas magnetic resonance imaging (HP MRI)—a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces—is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of 3He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces; (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces; and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation. PMID:24920074

  14. Hyperpolarized gas diffusion MRI for the study of atelectasis and acute respiratory distress syndrome.

    PubMed

    Cereda, Maurizio; Xin, Yi; Kadlecek, Stephen; Hamedani, Hooman; Rajaei, Jennia; Clapp, Justin; Rizi, Rahim R

    2014-12-01

    Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury, which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of computed tomography, positron emission tomography, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized (HP) gas MRI--a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces--is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of (3) He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces, (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces, and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation. Copyright © 2014 John Wiley & Sons, Ltd.

  15. Endotracheal tube resistance and inertance in a model of mechanical ventilation of newborns and small infants-the impact of ventilator settings on tracheal pressure swings.

    PubMed

    Hentschel, Roland; Buntzel, Julia; Guttmann, Josef; Schumann, Stefan

    2011-09-01

    Resistive properties of endotracheal tubes (ETTs) are particularly relevant in newborns and small infants who are generally ventilated through ETTs with a small inner diameter. The ventilation rate is also high and the inspiratory time (ti) is short. These conditions effectuate high airway flows with excessive flow acceleration, so airway resistance and inertance play an important role. We carried out a model study to investigate the impact of varying ETT size, lung compliance and ventilator settings, such as peak inspiratory pressure (PIP), positive end expiratory pressure (PEEP) and inspiratory time (ti) on the pressure-flow characteristics with respect to the resistive and inertive properties of the ETT. Pressure at the Y piece was compared to direct measurement of intratracheal pressure (P(trach)) at the tip of the ETT, and pressure drop (ΔP(ETT)) was calculated. Applying published tube coefficients (Rohrer's constants and inertance), P(trach) was calculated from ventilator readings and compared to measured P(trach) using the root-mean-square error. The most relevant for ΔP(ETT) was the ETT size, followed by (in descending order) PIP, compliance, ti and PEEP, with gas flow velocity being the principle in common for all these parameters. Depending on the ventilator settings ΔP(ETT) exceeded 8 mbar in the smallest 2.0 mm ETT. Consideration of inertance as an additional effect in this setting yielded a better agreement of calculated versus measured P(trach) than Rohrer's constants alone. We speculate that exact tracheal pressure tracings calculated from ventilator readings by applying Rohrer's equation and the inertance determination to small size ETTs would be helpful. As an integral part of ventilator software this would (1) allow an estimate of work of breathing and implementation of an automatic tube compensation, and (2) be important for gentle ventilation in respiratory care, especially of small infants, since it enables the physician to estimate

  16. 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.

  17. Hyperoxic Acute Lung Injury

    PubMed Central

    Kallet, Richard H; Matthay, Michael A

    2013-01-01

    Prolonged breathing of very high FIO2 (FIO2 ≥ 0.9) uniformly causes severe hyperoxic acute lung injury (HALI) and, without a reduction of FIO2, is usually fatal. The severity of HALI is directly proportional to PO2 (particularly above 450 mm Hg, or an FIO2 of 0.6) and exposure duration. Hyperoxia produces extraordinary amounts of reactive O2 species that overwhelms natural antioxidant defenses and destroys cellular structures through several pathways. Genetic predisposition has been shown to play an important role in HALI among animals, and some genetics-based epidemiologic research suggests that this may be true for humans as well. Clinically, the risk of HALI likely occurs when FIO2exceeds 0.7, and may become problematic when FIO2 exceeds 0.8 for an extended period of time. Both high-stretch mechanical ventilation and hyperoxia potentiate lung injury and may promote pulmonary infection. During the 1960s, confusion regarding the incidence and relevance of HALI largely reflected such issues as the primitive control of FIO2, the absence of PEEP, and the fact that at the time both ALI and ventilator-induced lung injury were unknown. The advent of PEEP and precise control over FIO2, as well as lung-protective ventilation, and other adjunctive therapies for severe hypoxemia, has greatly reduced the risk of HALI for the vast majority of patients requiring mechanical ventilation in the 21st century. However, a subset of patients with very severe ARDS requiring hyperoxic therapy is at substantial risk for developing HALI, therefore justifying the use of such adjunctive therapies. PMID:23271823

  18. Evaluation of lung infiltration score to predict postural hypoxemia in ventilated acute respiratory distress syndrome patients and the lateralization of skin pressure sore.

    PubMed

    Tripathi, Mukesh; Pandey, Mamta; Nepal, Bharat; Rai, Hari; Bhattarai, Balkrishna

    2009-09-01

    Mechanical ventilation with positive end expiratory pressure (PEEP) is associated with unequal aeration of lungs in acute respiratory distress syndrome (ARDS) patients. Therefore, patients may develop asymmetric atelectasis and postural hypoxemia during lateral positioning. To validate proposed lung infiltration score (LIS) based on chest x-ray to predict postural hypoxemia and lateralization of skin sores in ARDS patients. University hospital ICU. Prospective, observational study of consecutive patients. Sixteen adult patients of both genders on mechanical ventilation with PEEP for 24 to <48 hours. On chest x-ray, 6 segments were identified on each lung. The proposed LIS points (0- normal; 1- patchy infiltrates; 2- white infiltrates matching heart shadow) were assigned to each segment. Without changing ventilation parameters, supine, left and right lateral positions at 45 degrees tilt were randomly changed. At the end of 20 minutes of ventilation in each position, we observed arterial oxygen saturation, hemodynamic and arterial blood gases. Later, position change protocol (4 hourly) was practiced in ICU, and skin pressure sore grading was noted within a week of ICU stay. Nonparametric Bland and Altman correlation analysis, ANOVA and Student t test. Arterial oxygenation (PaO2/FiO2 = 313 +/- 145.6) was significantly (P<0.01) higher in better lung (lower LIS)-down position than supine (PaO2/FiO2 = 199 +/- 70.2) or a better lung-up position (PaO2/FiO2 = 165 +/- 64.8). The positioning-related arterial oxygenation was significant (P<0.05) at LIS asymmetry > or =3 between two lungs. The LIS mapping on chest x-ray was useful to differentiate between asymmetric lung disease and postural hypoxemia in ICU patients, which predisposed patients to early skin sore changes on higher LIS side.

  19. A respiratory-gated micro-CT comparison of respiratory patterns in free-breathing and mechanically ventilated rats.

    PubMed

    Ford, Nancy L; McCaig, Lynda; Jeklin, Andrew; Lewis, James F; Veldhuizen, Ruud A W; Holdsworth, David W; Drangova, Maria

    2017-01-01

    In this study, we aim to quantify the differences in lung metrics measured in free-breathing and mechanically ventilated rodents using respiratory-gated micro-computed tomography. Healthy male Sprague-Dawley rats were anesthetized with ketamine/xylazine and scanned with a retrospective respiratory gating protocol on a GE Locus Ultra micro-CT scanner. Each animal was scanned while free-breathing, then intubated and mechanically ventilated (MV) and rescanned with a standard ventilation protocol (56 bpm, 8 mL/kg and PEEP of 5 cm H2O) and again with a ventilation protocol that approximates the free-breathing parameters (88 bpm, 2.14 mL/kg and PEEP of 2.5 cm H2O). Images were reconstructed representing inspiration and end expiration with 0.15 mm voxel spacing. Image-based measurements of the lung lengths, airway diameters, lung volume, and air content were compared and used to calculate the functional residual capacity (FRC) and tidal volume. Images acquired during MV appeared darker in the airspaces and the airways appeared larger. Image-based measurements showed an increase in lung volume and air content during standard MV, for both respiratory phases, compared with matched MV and free-breathing. Comparisons of the functional metrics showed an increase in FRC for mechanically ventilated rats, but only the standard MV exhibited a significantly higher tidal volume than free-breathing or matched MV Although standard mechanical ventilation protocols may be useful in promoting consistent respiratory patterns, the amount of air in the lungs is higher than in free-breathing animals. Matching the respiratory patterns with the free-breathing case allowed similar lung morphology and physiology measurements while reducing the variability in the measurements. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  20. Choosing the frequency of deep inflation in mice: balancing recruitment against ventilator-induced lung injury.

    PubMed

    Allen, Gilman B; Suratt, Benjamin T; Rinaldi, Lisa; Petty, Joseph M; Bates, Jason H T

    2006-10-01

    Low tidal volume (Vt) ventilation is protective against ventilator-induced lung injury but can promote development of atelectasis. Periodic deep inflation (DI) can open the lung, but if delivered too frequently may cause damage via repeated overdistention. We therefore examined the effects of varying DI frequency on lung mechanics, gas exchange, and biomarkers of injury in mice. C57BL/6 males were mechanically ventilated with positive end-expiratory pressure (PEEP) of 2 cmH2O for 2 h. One high Vt group received a DI with each breath (HV). Low Vt groups received 2 DIs after each hour of ventilation (LV) or 2 DIs every minute (LVDI). Control groups included a nonventilated surgical sham and a group receiving high Vt with zero PEEP (HVZP). Respiratory impedance was measured every 4 min, from which tissue elastance (H) and damping (G) were derived. G and H rose progressively during LV and HVZP, but returned to baseline after hourly DI during LV. During LVDI and HV, G and H remained low and gas exchange was superior to that of LV. Bronchoalveolar lavage fluid protein was elevated in HV and HVZP but was not different between LV and LVDI. Lung tissue IL-6 and IL-1beta levels were elevated in HVZP and lower in LVDI compared with LV. We conclude that frequent DI can safely improve gas exchange and lung mechanics and may confer protection from biotrauma. Differences between LVDI and HV suggest that an optimal frequency range of DI exists, within which the benefits of maintaining an open lung outweigh injury incurred from overdistention.

  1. The Evaluation of a Pulmonary Display to Detect Adverse Respiratory Events Using High Resolution Human Simulator

    PubMed Central

    Wachter, S. Blake; Johnson, Ken; Albert, Robert; Syroid, Noah; Drews, Frank; Westenskow, Dwayne

    2006-01-01

    Objective Authors developed a picture-graphics display for pulmonary function to present typical respiratory data used in perioperative and intensive care environments. The display utilizes color, shape and emergent alerting to highlight abnormal pulmonary physiology. The display serves as an adjunct to traditional operating room displays and monitors. Design To evaluate the prototype, nineteen clinician volunteers each managed four adverse respiratory events and one normal event using a high-resolution patient simulator which included the new displays (intervention subjects) and traditional displays (control subjects). Between-group comparisons included (i) time to diagnosis and treatment for each adverse respiratory event; (ii) the number of unnecessary treatments during the normal scenario; and (iii) self-reported workload estimates while managing study events. Measurements Two expert anesthesiologists reviewed video-taped transcriptions of the volunteers to determine time to treat and time to diagnosis. Time values were then compared between groups using a Mann-Whitney-U Test. Estimated workload for both groups was assessed using the NASA-TLX and compared between groups using an ANOVA. P-values < 0.05 were considered significant. Results Clinician volunteers detected and treated obstructed endotracheal tubes and intrinsic PEEP problems faster with graphical rather than conventional displays (p < 0.05). During the normal scenario simulation, 3 clinicians using the graphical display, and 5 clinicians using the conventional display gave unnecessary treatments. Clinician-volunteers reported significantly lower subjective workloads using the graphical display for the obstructed endotracheal tube scenario (p < 0.001) and the intrinsic PEEP scenario (p < 0.03). Conclusion Authors conclude that the graphical pulmonary display may serve as a useful adjunct to traditional displays in identifying adverse respiratory events. PMID:16929038

  2. Effect of prone positioning on cannula function and impaired oxygenation during extracorporeal circulation.

    PubMed

    Masuda, Yoshiki; Tatsumi, Hiroomi; Imaizumi, Hitoshi; Gotoh, Kyoko; Yoshida, Shinichiro; Chihara, Shinya; Takahashi, Kanako; Yamakage, Michiaki

    2014-03-01

    Prone ventilation is an effective method for improving oxygenation in patients with acute respiratory failure. However, in extracorporeal circulation, there is a risk of cannula-related complications when changing the position. In this study, we investigated cannula-related complications when changing position for prone ventilation and the effect of prone ventilation on impaired oxygenation in patients who underwent extracorporeal membrane oxygenation (ECMO). The study subjects were patients who underwent prone ventilation during ECMO in the period from 2004 to 2011. Indication for prone ventilation was the presence of dorsal infiltration shown by lung computed tomography. Factors investigated were cannula insertion site, dislodgement or obstruction of the cannula, malfunction of vascular access and unplanned dislodgement of the catheters when changing position. Mean arterial pressure, PaO2/FiO2, PEEP level, blood flow and rotation speed of the pump were also determined before and after position change. Five patients were selected as study subjects. The mean duration of prone positioning was 15.3 ± 0.5 h. Strict management during position changes prevented cannula-related complications in the patients who underwent extracorporeal circulation. There were no significant changes in mean arterial pressure, PEEP level, blood flow and rotation speed of the pump when changing position. Low PaO2/FiO2 prior to prone ventilation was significantly increased after supine to prone and then prone to supine position. Prone positioning to improve impaired oxygenation is a safe procedure and not a contraindication in patients receiving extracorporeal circulation.

  3. Aging-related changes in respiratory system mechanics and morphometry in mice.

    PubMed

    Elliott, Jonathan E; Mantilla, Carlos B; Pabelick, Christina M; Roden, Anja C; Sieck, Gary C

    2016-07-01

    Previous work investigating respiratory system mechanics in mice has reported an aging-related increase in compliance and mean linear intercept (Lm). However, these changes were assessed using only a young (2-mo-old) and old (20- and 26-mo-old) group yet were interpreted to reflect a linear evolution across the life span. Therefore, to investigate respiratory system mechanics and lung morphometry across a more complete spectrum of ages, we utilized 2 (100% survival, n = 6)-, 6 (100% survival, n = 12)-, 18 (90% survival, n = 12)-, 24 (75% survival, n = 12)-, and 30 (25% survival, n = 12)-mo-old C57BL/6 mice. We found a nonlinear aging-related decrease in respiratory system resistance and increase in dynamic compliance and hysteresis between 2- and 24-mo-old mice. However, in 30-mo-old mice, respiratory system resistance increased, and dynamic compliance and hysteresis decreased relative to 24-mo-old mice. Respiratory system impedance spectra were measured between 1-20.5 Hz at positive end-expiratory pressures (PEEP) of 1, 3, 5, and 7 cmH2O. Respiratory system resistance and reactance at each level of PEEP were increased and decreased, respectively, only in 2-mo-old animals. No differences in the respiratory system impedance spectra were observed in 6-, 18-, 24-, and 30-mo-old mice. Additionally, lungs were fixed following tracheal instillation of 4% paraformaldehyde at 25 cmH2O and processed for Lm and airway collagen deposition. There was an aging-related increase in Lm consistent with emphysematous-like changes and no evidence of increased airway collagen deposition. Accordingly, we demonstrate nonlinear aging-related changes in lung mechanics and morphometry in C57BL/6 mice.

  4. A closed-loop controller for mechanical ventilation of patients with ARDS.

    PubMed

    Anderson, Jeffrey R; East, Thomas D

    2002-01-01

    Mechanical ventilators are routinely used to care for patients who cannot adequately breath on their own. Management of mechanical ventilation often involves a careful watch of the patient's arterial blood-oxygen tension and requires frequent adjustment of ventilation parameters to optimize the therapy. This situation lends itself as a candidate for closed-loop control. This report describes a closed-loop control system based on well-established protocols to systematically maintain appropriate levels of positive end-expiratory pressure (PEEP) and inspired oxygen (FiO2) in patients with Adult Respiratory Distress Syndrome (ARDS). The closed-loop control system consists of an in-dwelling arterial oxygenation (PaO2) sensor (Pfizer Continucath), coupled to a Macintosh computer that continuously controls FiO2 and PEEP settings on a Hamilton Amadeus ventilator. The implemented protocols provide continuous closed-loop control of oxygenation and a balance between patient need and minimal therapy. The controller is based on a traditional proportional-integral-derivative (PID) approach. The idea is to control, or maintain, the patient's PaO2 level at a target value determined, or set, by the patient's physician. The controller also features non-linear and adaptive characteristics that allow the system to respond more aggressively to "threatening" levels of PaO2. Another benefit of the control system is the ability to display, monitor, record and store all system parameters, settings, and control variables for future analysis and study. The system was extensively tested in the laboratory and in animal trials prior to use on human subjects. The results of a small clinical trial indicated that the system maintained control of the patient's therapy nearly 84% of the time. During the remainder of this time, the controller was interrupted primarily for suctioning, PaO2 sensor calibration or replacement. The response of the closed-loop controller was found to be appropriate

  5. Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model.

    PubMed

    Bouwmeester, J Christopher; Belenkie, Israel; Shrive, Nigel G; Tyberg, John V

    2014-09-01

    Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in 'excess' quantities which were treated as wave-related.Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)).Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e.pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave.

  6. [Case report of re-expansion pulmonary edema in a patient with anorexia nervosa after removal of a huge ovarian tumor].

    PubMed

    Hari, Junko; Arai, Masayasu; Kosaka, Yasuharu; Toda, Masaya; Kuroiwa, Masayuki; Okamoto, Hirotsugu

    2014-04-01

    We described a case of 19-year-old female who developed re-expansion pulmonary edema (RPE) after removal of a huge ovarian tumor. Altered lung volume after the surgery was observed by chest X-ray. Preoperatively, the lung was highly compressed by the tumor. Patient was intubated under general anesthesia and was ventilated by pressure controlled mode with only 5 cmH2O of positive end-expiratory pressure (PEEP). P/F ratio was changed from 163 to 444 after removal of the tumor. At the end of the surgery, P/F ratio decreased to 263 with yellow frothy sputum in the endotracheal tube and we diagnosed re-expansion pulmonary edema based on appearing yellow frothy sputum and chest X-ray. No recruitment procedure was carried out through the course except positive pressure ventilation with 5 cmH2O of PEEP in the intensive care unit after surgery. Twelve hours after the surgery, we could not confirm the recovery of lung volume on chest X-ray; however the patient was extubated because of P/F ratio increasing to 507. After 8 days of the surgery, the chest X-ray showed recovery of the lung volume to almost normal size. In this case, the compressed lung needed almost 1 week to recover the lung volume. This change in chest X-ray might indicate inadequate recovery of lung volume by recruitment maneuver and this should be avoided in order not to allow development of unfavorable clinical course of RPE.

  7. Massive aspiration past the tracheal tube cuff caused by closed tracheal suction system.

    PubMed

    Dave, Mital H; Frotzler, Angela; Madjdpour, Caveh; Koepfer, Nelly; Weiss, Markus

    2011-01-01

    Aspiration past the tracheal tube cuff has been recognized to be a risk factor for the development of ventilator-associated pneumonia (VAP). This study investigated the effect of closed tracheal suctioning on aspiration of fluid past the tracheal tube cuff in an in vitro benchtop model. High-volume low pressure tube cuffs of 7.5 mm internal diameter (ID) were placed in a 22 mm ID artificial trachea connected to a test lung. Positive pressure ventilation (PPV) with 15 cm H₂O peak inspiratory pressure and 5 cm H₂O positive end-expiratory pressure (PEEP) was used. A closed tracheal suction system (CTSS) catheter (size 14Fr) was attached to the tracheal tube and suction was performed for 5, 10, 15, or 20 seconds under 200 or 300 cm H₂O suction pressures. Amount of fluid (mL) aspirated along the tube cuff and the airway pressure changes were recorded for each suction procedure. Fluid aspiration during different suction conditions was compared using Kruskal-Wallis and Mann-Whitney test (Bonferroni correction [α = .01]). During 10, 15, and 20 seconds suction, airway pressure consistently dropped down to -8 to -13 cm H₂O (P < .001) from the preset level. Fluid aspiration was never observed under PPV + PEEP but occurred always during suctioning. Aspiration along the tube cuff was higher with -300 cm H₂O than with -200 cm H₂O suction pressure (P < .001) and was much more during 15 and 20 seconds suction time as compared to 5 seconds (P < .001). Massive aspiration of fluid occurs along the tracheal tube cuff during suction with the closed tracheal suction system. © SAGE Publications 2011.

  8. Suspended animation inducer hydrogen sulfide is protective in an in vivo model of ventilator-induced lung injury

    PubMed Central

    Aslami, Hamid; Heinen, André; Roelofs, Joris J. T. H.; Zuurbier, Coert J.; Schultz, Marcus J.

    2010-01-01

    Purpose Acute lung injury is characterized by an exaggerated inflammatory response and a high metabolic demand. Mechanical ventilation can contribute to lung injury, resulting in ventilator-induced lung injury (VILI). A suspended-animation-like state induced by hydrogen sulfide (H2S) protects against hypoxia-induced organ injury. We hypothesized that suspended animation is protective in VILI by reducing metabolism and thereby CO2 production, allowing for a lower respiratory rate while maintaining adequate gas exchange. Alternatively, H2S may reduce inflammation in VILI. Methods In mechanically ventilated rats, VILI was created by application of 25 cmH2O positive inspiratory pressure (PIP) and zero positive end-expiratory pressure (PEEP). Controls were lung-protective mechanically ventilated (13 cmH2O PIP, 5 cmH2O PEEP). H2S donor NaHS was infused continuously; controls received saline. In separate control groups, hypothermia was induced to reproduce the H2S-induced fall in temperature. In VILI groups, respiratory rate was adjusted to maintain normo-pH. Results NaHS dose-dependently and reversibly reduced body temperature, heart rate, and exhaled amount of CO2. In VILI, NaHS reduced markers of pulmonary inflammation and improved oxygenation, an effect which was not observed after induction of deep hypothermia that paralleled the NaHS-induced fall in temperature. Both NaHS and hypothermia allowed for lower respiratory rates while maintaining gas exchange. Conclusions NaHS reversibly induced a hypometabolic state in anesthetized rats and protected from VILI by reducing pulmonary inflammation, an effect that was in part independent of body temperature. Electronic supplementary material The online version of this article (doi:10.1007/s00134-010-2022-2) contains supplementary material, which is available to authorized users. PMID:20721529

  9. Early induction of direct hemoperfusion with a polymyxin-B immobilized column is associated with amelioration of hemodynamic derangement and mortality in patients with septic shock.

    PubMed

    Chihara, Shinya; Masuda, Yoshiki; Tatsumi, Hiroomi; Nakano, Kota; Shimada, Tomokazu; Murohashi, Takao; Yamakage, Michiaki

    2017-03-01

    This study was conducted to clarify the effectiveness of induction timing of direct hemoperfusion with a polymyxin-B immobilized column (PMX-DHP) for amelioration of hemodynamic derangement and outcome in patients with septic shock. Suspected Gram-negative septic shock patients who received PMX-DHP therapy from January 2010 to December 2014 in our ICU were enrolled in this study. The patients were divided into two groups that received PMX-DHP therapy within 8 h (early group) and more than 8 h (late group) from catecholamine administration. Changes in catecholamine dose [catecholamine index (CAI)], catecholamine dose/mean arterial pressure [catecholamine index pressure (CAIP)], PaO2/FiO2 and PEEP level were determined at the start of and 24 h after the start of PMX-DHP therapy. Ventilator-free days (VFD), ICU-free days (IFD), 28-day and hospital mortality were also determined. There were no significant differences in patients' characteristics between the two groups. CAI and CAIP were significantly decreased in the early group. PaO2/FiO2 was not changed whereas PEEP level in the early group was significantly decreased during PMX-DHP therapy. IFD and VFD were not different in the two groups. Mortality at 28 days was significantly improved in the early group. Endotoxin acts as an early mediator in sepsis patients with suspected Gram-negative infection. Earlier induction of PMX-DHP therapy as in our study is closely associated with earlier weaning from hemodynamic derangement and with improvement of mortality. Therefore, early induction of PMX-DHP therapy is recommended for the treatment of septic shock in patients with presumed Gram-negative infection.

  10. Use of positive-pressure ventilation in dogs and cats: 41 cases (1990-1992).

    PubMed

    King, L G; Hendricks, J C

    1994-04-01

    Intermittent positive-pressure ventilation (PPV) is an invasive means of respiratory support that is indicated in animals with central and peripheral neuromuscular disease, as well as in those with primary disorders of the lung parenchyma. We reviewed the medical records of 34 dogs and 7 cats treated with PPV. The animals could be allotted to 2 groups; group 1 (21/41) had primary failure of ventilation attributable to neuromuscular disease or airway obstruction, and group 2 (20/41) had primary pulmonary parenchymal disease. Mean inspiratory time was 1.02 +/- 0.2 seconds (range, 0.6 to 1.5 seconds). Mean inspiratory flow was 26.9 +/- 18.5 L/min (range, 7 to 87 L/min), and was positively correlated with body weight (R = 0.57). Mean set respiratory rate was 19.6 +/- 10 breaths/min (range, 5 to 60 breaths/min), with mean tidal volume of 15.5 +/- 6.2 ml/kg of body weight. Positive end-expiratory pressure (PEEP) was required in 14 of 20 dogs in group 2. Mean peak airway pressure in group 1 was 21.6 +/- 6.3 cm of H2O, whereas in group 2 it was 32.9 +/- 12.5 cm of H2O. The higher peak airway pressure in group-2 dogs reflected poor lung compliance and the use of PEEP in dogs with parenchymal lung disease. Mean duration of PPV was 28.2 +/- 29.4 hours (range, 2 to 137 hours). The overall survival rate was 39% (16/41).(ABSTRACT TRUNCATED AT 250 WORDS)

  11. [Acute respiratory distress syndrome].

    PubMed

    Estenssoro, Elisa; Dubin, Arnaldo

    Acute respiratory distress syndrome (ARDS) is an acute respiratory failure produced by an inflammatory edema secondary to increased lung capillary permeability. This causes alveolar flooding and subsequently deep hypoxemia, with intrapulmonary shunt as its most important underlying mechanism. Characteristically, this alteration is unresponsive to high FIO2 and only reverses with end-expiratory positive pressure (PEEP). Pulmonary infiltrates on CXR and CT are the hallmark, together with decreased lung compliance. ARDS always occurs within a week of exposition to a precipitating factor; most frequently pneumonia, shock, aspiration of gastric contents, sepsis, and trauma. In CT scan, the disease is frequently inhomogeneous, with gravitational infiltrates coexisting with normal-density areas and also with hyperaerated parenchyma. Mortality is high (30-60%) especially in ARDS associated with septic shock and neurocritical diseases. The cornerstone of therapy lies in the treatment of the underlying cause and in the use mechanical ventilation which, if inappropriately administered, can lead to ventilator-induced lung injury. Tidal volume = 6 ml/kg of ideal body weight to maintain an end-inspiratory (plateau) pressure = 30 cm H2O ("protective ventilation") is the only variable consistently associated with decreased mortality. Moderate-to-high PEEP levels are frequently required to treat hypoxemia, yet no specific level or titration strategy has improved outcomes. Recently, the use of early prone positioning in patients with PaO2/FIO2 = 150 was associated with increased survival. In severely hypoxemic patients, it may be necessary to use adjuvants of mechanical ventilation as recruitment maneuvers, pressure-controlled modes, neuromuscular blocking agents, and extracorporeal-membrane oxygenation. Fluid restriction appears beneficial.

  12. WNT/β-catenin signaling is modulated by mechanical ventilation in an experimental model of acute lung injury.

    PubMed

    Villar, Jesús; Cabrera, Nuria E; Casula, Milena; Valladares, Francisco; Flores, Carlos; López-Aguilar, Josefina; Blanch, Lluis; Zhang, Haibo; Kacmarek, Robert M; Slutsky, Arthur S

    2011-07-01

    The mechanisms involved in lung injury progression during acute lung injury (ALI) are still poorly understood. Because WNT/β-catenin signaling has been shown to be involved in epithelial cell injury and hyperplasia during inflammation and sepsis, we hypothesized that it would be modulated by mechanical ventilation (MV) in an experimental model of sepsis-induced ALI. This study was a prospective, randomized, controlled animal study performed using adult male Sprague-Dawley rats. Sepsis was induced by cecal ligation and perforation. At 18 h, surviving animals were randomized to spontaneous breathing or two strategies of MV for 4 h: low tidal volume (V (T)) (6 ml/kg) plus 10 cmH2O of positive end-expiratory pressure (PEEP) versus high (20 ml/kg) tidal volume (V (T)) with zero PEEP. Histological evaluation, measurements of WNT5A, total β-catenin, and matrix metalloproteinase-7 (MMP7) protein levels by Western blot, and their immunohistochemical localization in the lungs were analyzed. Sepsis and high-V (T) MV caused lung inflammation and perivascular edema with cellular infiltrates and collagen deposition. Protein levels of WNT5A, β-catenin, and MMP7 in the lungs were increased in animals with sepsis-induced ALI. High-V (T) MV was associated with higher levels of WNT5A, β-catenin, and MMP7 protein levels (p < 0.001), compared to healthy control animals. By contrast, low-V (T) MV markedly reduced WNT5A, β-catenin, and MMP7 protein levels (p < 0.001). Our findings demonstrate that the WNT/β-catenin signaling pathway is modulated early during sepsis and ventilator-induced lung injury, suggesting that activation of this pathway could play an important role in both lung injury progression and repair.

  13. Tracheal gas insufflation-pressure control versus volume control ventilation. A lung model study.

    PubMed

    Imanaka, H; Kacmarek, R M; Ritz, R; Hess, D

    1996-03-01

    Tracheal gas insufflation (TGI) has been recommended as an adjunct to mechanical ventilation in the presence of elevated Pa CO2. Based on our initial clinical experience with continuous flow TGI and pressure control ventilation (PCV), we were concerned about elevation in peak airway pressure as TGI was applied. In a lung model, we evaluated the effects of continuous flow TGI during both PCV and volume control ventilation (VCV). A single compartment lung model was configured with an artificial trachea into which an 8-mm endotracheal tube was positioned. TGI was established with a 16-G catheter positioned 2 cm beyond the tip of the endotracheal tube. Ventilation was provided by a Puritan-Bennett 7200ae ventilator with PCV 20 cm H2O or VCV with a tidal volume (VTt) similar to that with PCV. A rate of 15 breaths/min and PEEP of 10 cm H2O were used throughout. Inspiratory times (TI) of 1.0, 1.5, 2.0, and 2.5 s were used with TGI of 0, 4, 8, and 12 L/min. Lung model compliance (ml/cm H2O) and resistance (cm H2O/L/s) combinations of 20/20, 20/5, and 50/20 were used. Auto-PEEP, VT, and peak alveolar and airway opening pressures increased as TGI and Ti increased, regardless of lung mechanics settings (p<0.01). All increases were greater with VCV than PCV (p<0.05). Continuous flow TGI with both PCV and VT-uncorrected VCV may result in marked increases in Vt and system pressures, especially at long TI.

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

    PubMed Central

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

    2011-01-01

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

  15. Measuring dead-space in acute lung injury.

    PubMed

    Kallet, R H

    2012-11-01

    Several recent studies have advanced our understanding of dead-space ventilation in patients with acute lung injury/acute respiratory distress syndrome (ALI/ARDS). They have demonstrated the utility of measuring physiologic dead-space-to-tidal volume ratio (VD/VT) and related variables in assessing outcomes as well as therapeutic interventions. These studies have included the evaluation of mortality risk, pulmonary perfusion, as well as the effectiveness of drug therapy, prone positioning, positive end-expiratory pressure (PEEP) titration, and inspiratory pattern in improving gas exchange. In patients with ALI/ARDS managed with lung-protective ventilation a significant relationship between elevated VD/VT and increased mortality continues to be reported in both early and intermediate phases of ALI/ARDS. Some clinical evidence now supports the suggestion that elevated VD/VT in part reflects the severity of pulmonary vascular endothelial damage. Monitoring VD/VT also appears useful in assessing alveolar recruitment when titrating PEEP and may be a particularly expedient method for assessing the effectiveness of prone positioning. It also has revealed how subtle manipulations of inspiratory time and pattern can improve CO(2) excretion. Much of this has been accomplished using volumetric capnography. This allows for more sophisticated measurements of pulmonary gas exchange function including: alveolar VD/VT, the volume of CO(2) excretion and the slope of the alveolar plateau which reflects ventilation: perfusion heterogeneity. Many of these measurements now can be made non-invasively which should only increase the research and clinical utility of volumetric capnography in studying and managing patients with ALI/ARDS.

  16. Genesis of the characteristic pulmonary venous pressure waveform as described by the reservoir-wave model

    PubMed Central

    Bouwmeester, J Christopher; Belenkie, Israel; Shrive, Nigel G; Tyberg, John V

    2014-01-01

    Conventional haemodynamic analysis of pulmonary venous and left atrial (LA) pressure waveforms yields substantial forward and backward waves throughout the cardiac cycle; the reservoir wave model provides an alternative analysis with minimal waves during diastole. Pressure and flow in a single pulmonary vein (PV) and the main pulmonary artery (PA) were measured in anaesthetized dogs and the effects of hypoxia and nitric oxide, volume loading, and positive-end expiratory pressure (PEEP) were observed. The reservoir wave model was used to determine the reservoir contribution to PV pressure and flow. Subtracting reservoir pressure and flow resulted in ‘excess’ quantities which were treated as wave-related. Wave intensity analysis of excess pressure and flow quantified the contributions of waves originating upstream (from the PA) and downstream (from the LA and/or left ventricle (LV)). Major features of the characteristic PV waveform are caused by sequential LA and LV contraction and relaxation creating backward compression (i.e. pressure-increasing) waves followed by decompression (i.e. pressure-decreasing) waves. Mitral valve opening is linked to a backwards decompression wave (i.e. diastolic suction). During late systole and early diastole, forward waves originating in the PA are significant. These waves were attenuated less with volume loading and delayed with PEEP. The reservoir wave model shows that the forward and backward waves are negligible during LV diastasis and that the changes in pressure and flow can be accounted for by the discharge of upstream reservoirs. In sharp contrast, conventional analysis posits forward and backward waves such that much of the energy of the forward wave is opposed by the backward wave. PMID:25015922

  17. Positive-pressure ventilation during transport: a randomized crossover study of self-inflating and flow-inflating resuscitators in a simulation model.

    PubMed

    Lucy, Malcolm J; Gamble, Jonathan J; Daku, Brian L; Bryce, Rhonda D; Rana, Masud

    2014-12-01

    Positive-pressure ventilation during transport of intubated patients is generally delivered via a hand-pressurized device. Of these devices, self-inflating resuscitators (SIR) and flow-inflating resuscitators (FIR) constitute the two major types used. Selection of a particular device for transport, however, remains largely an institutional practice. To evaluate the hypothesis that transport ventilation goals of intubated pediatric patients are better achieved using an FIR compared to an SIR. This randomized crossover simulation study compared the performance of SIR and FIR among anesthesia providers in a pediatric transport scenario. Subjects hand-ventilated a test lung while simultaneously maneuvering a stretcher bed to simulate patient transport. Hand ventilation was carried out using a Jackson-Rees circuit (FIR) and a Laerdal pediatric silicone resuscitator (SIR). The primary outcome was the proportion of total breaths delivered within the predefined target PIP/PEEP range (30+/- 3, 10+/- 3 cm H2O). Secondary outcomes included proportion of total breaths delivered with operationally defined unacceptable breath variables (PIP > 35 cm H2O or PEEP < 5 cm H2O). Overall, participants were four times more likely to deliver target breaths and one-third less likely to deliver unacceptable breaths using the FIR compared to the SIR. When comparing device performance, a 44% increase in the proportions of target breaths and a 40.4% decrease in unacceptable breaths using the FIR were observed (P < 0.0001 for both). Hand ventilation during patient transport is superior using the FIR compared to the SIR to achieve target ventilatory goals and avoid unacceptable ventilatory cycles. © 2014 John Wiley & Sons Ltd.

  18. Antenatal and postnatal corticosteroid and resuscitation induced lung injury in preterm sheep

    PubMed Central

    2009-01-01

    Background Initiation of ventilation using high tidal volumes in preterm lambs causes lung injury and inflammation. Antenatal corticosteroids mature the lungs of preterm infants and postnatal corticosteroids are used to treat bronchopulmonary dysplasia. Objective To test if antenatal or postnatal corticosteroids would decrease resuscitation induced lung injury. Methods 129 d gestational age lambs (n = 5-8/gp; term = 150 d) were operatively delivered and ventilated after exposure to either 1) no medication, 2) antenatal maternal IM Betamethasone 0.5 mg/kg 24 h prior to delivery, 3) 0.5 mg/kg Dexamethasone IV at delivery or 4) Cortisol 2 mg/kg IV at delivery. Lambs then were ventilated with no PEEP and escalating tidal volumes (VT) to 15 mL/kg for 15 min and then given surfactant. The lambs were ventilated with VT 8 mL/kg and PEEP 5 cmH20 for 2 h 45 min. Results High VT ventilation caused a deterioration of lung physiology, lung inflammation and injury. Antenatal betamethasone improved ventilation, decreased inflammatory cytokine mRNA expression and alveolar protein leak, but did not prevent neutrophil influx. Postnatal dexamethasone decreased pro-inflammatory cytokine expression, but had no beneficial effect on ventilation, and postnatal cortisol had no effect. Ventilation increased liver serum amyloid mRNA expression, which was unaffected by corticosteroids. Conclusions Antenatal betamethasone decreased lung injury without decreasing lung inflammatory cells or systemic acute phase responses. Postnatal dexamethasone or cortisol, at the doses tested, did not have important effects on lung function or injury, suggesting that corticosteroids given at birth will not decrease resuscitation mediated injury. PMID:20003512

  19. Inflammation and lung maturation from stretch injury in preterm fetal sheep.

    PubMed

    Hillman, Noah H; Polglase, Graeme R; Pillow, J Jane; Saito, Masatoshi; Kallapur, Suhas G; Jobe, Alan H

    2011-02-01

    Mechanical ventilation is a risk factor for the development of bronchopulmonary dysplasia in premature infants. Fifteen minutes of high tidal volume (V(T)) ventilation induces inflammatory cytokine expression in small airways and lung parenchyma within 3 h. Our objective was to describe the temporal progression of cytokine and maturation responses to lung injury in fetal sheep exposed to a defined 15-min stretch injury. After maternal anesthesia and hysterotomy, 129-day gestation fetal lambs (n = 7-8/group) had the head and chest exteriorized. Each fetus was intubated, and airway fluid was gently removed. While placental support was maintained, the fetus received ventilation with an escalating V(T) to 15 ml/kg without positive end-expiratory pressure (PEEP) for 15 min using heated, humidified 100% nitrogen. The fetus was then returned to the uterus for 1, 6, or 24 h. Control lambs received a PEEP of 2 cmH(2)O for 15 min. Tissue samples from the lung and systemic organs were evaluated. Stretch injury increased the early response gene Egr-1 and increased expression of pro- and anti-inflammatory cytokines within 1 h. The injury induced granulocyte/macrophage colony-stimulating factor mRNA and matured monocytes to alveolar macrophages by 24 h. The mRNA for the surfactant proteins A, B, and C increased in the lungs by 24 h. The airway epithelium demonstrated dynamic changes in heat shock protein 70 (HSP70) over time. Serum cortisol levels did not increase, and induction of systemic inflammation was minimal. We conclude that a brief period of high V(T) ventilation causes a proinflammatory cascade, a maturation of lung monocytic cells, and an induction of surfactant protein mRNA.

  20. The standard of care of patients with ARDS: ventilatory settings and rescue therapies for refractory hypoxemia.

    PubMed

    Bein, Thomas; Grasso, Salvatore; Moerer, Onnen; Quintel, Michael; Guerin, Claude; Deja, Maria; Brondani, Anita; Mehta, Sangeeta

    2016-05-01

    Severe ARDS is often associated with refractory hypoxemia, and early identification and treatment of hypoxemia is mandatory. For the management of severe ARDS ventilator settings, positioning therapy, infection control, and supportive measures are essential to improve survival. A precise definition of life-threating hypoxemia is not identified. Typical clinical determinations are: arterial partial pressure of oxygen < 60 mmHg and/or arterial oxygenation < 88 % and/or the ratio of PaO2/FIO2 < 100. For mechanical ventilation specific settings are recommended: limitation of tidal volume (6 ml/kg predicted body weight), adequate high PEEP (>12 cmH2O), a recruitment manoeuvre in special situations, and a 'balanced' respiratory rate (20-30/min). Individual bedside methods to guide PEEP/recruitment (e.g., transpulmonary pressure) are not (yet) available. Prone positioning [early (≤ 48 hrs after onset of severe ARDS) and prolonged (repetition of 16-hr-sessions)] improves survival. An advanced infection management/control includes early diagnosis of bacterial, atypical, viral and fungal specimen (blood culture, bronchoalveolar lavage), and of infection sources by CT scan, followed by administration of broad-spectrum anti-infectives. Neuromuscular blockage (Cisatracurium ≤ 48 hrs after onset of ARDS), as well as an adequate sedation strategy (score guided) is an important supportive therapy. A negative fluid balance is associated with improved lung function and the use of hemofiltration might be indicated for specific indications. A specific standard of care is required for the management of severe ARDS with refractory hypoxemia.

  1. Higher Fresh Gas Flow Rates Decrease Tidal Volume During Pressure Control Ventilation.

    PubMed

    Mohammad, Shazia; Gravenstein, Nikolaus; Gonsalves, Drew; Vasilopoulos, Terrie; Lampotang, Samsun

    2017-05-01

    We observed that increasing fresh gas flow (FGF) decreased exhaled tidal volume (VT) during pressure control ventilation (PCV). A literature search produced no such description whereby unintended VT changes occur with FGF changes during PCV. To model an infant's lungs, 1 lung of a mechanical lung model (Dual Adult TTL 1600; Michigan Instruments, Inc, Grand Rapids, MI) was set at a compliance of 0.0068 L/cm H2O. An Rp50 resistor (27.2 cm H2O/L/s at 15 L/min) simulated normal bronchial resistance. The simulated lung was connected to a pediatric breathing circuit via a 3.5-mm cuffed endotracheal tube. A ventilator with PCV capability (Model 7900; Aestiva, GE Healthcare, Madison, WI) measured exhaled VT, and a flow monitor (NICO; Respironics, Murraysville, PA) measured peak inspiratory flow, positive end-expiratory pressure (PEEP), and peak inspiratory pressure. In PCV mode, exhaled VT displayed by the ventilator at FGF rates of 1, 6, 10, and 15 L/min was manually recorded across multiple ventilator settings. This protocol was repeated for the Avance CS2 anesthesia machine (GE Healthcare). For the Aestiva, higher FGF rates in PCV mode decreased exhaled VT. Exhaled VT for FGFs of 1, 6, 10, and 15 L/min were on average 48, 34.9, 16.5, and 10 mL, respectively, at ventilator settings of inspiratory pressure of 10 cm H2O, PEEP of 0 cm H2O, and respiratory rate of 20 breaths/min. This is a decrease by up to 27%, 65.6%, and 79.2% when FGFs of 6, 10, and 15 L/min are compared with a FGF of 1 L/min, respectively. In the GE Avance CS2 at the same ventilator settings, VT for FGF rates of 1, 6, 10, and 15 L/min were on average 46, 43, 40.4, and 39.7 mL, respectively. The FGF effect on VT was not as pronounced with the GE Avance CS2 as with the GE Aestiva. FGF has a significant effect on VT during PCV in the Aestiva bellows ventilator, suggesting caution when changing FGF during PCV in infants. Our hypothesis is that at higher FGF rates, an inadvertent PEEP is developed by the flow

  2. Effects of Different Tidal Volume Ventilation on Paraquat-Induced Acute Lung Injury in Piglets

    PubMed Central

    Lan, Chao; Wang, Jinzhu; Li, Li; Li, Haina; Li, Lu; Su, Qianqian; Che, Lu; Liu, Lanping; Di, Min

    2015-01-01

    Background The aim of this study was to explore the effects of different tidal volume (VT) ventilation on paraquat-induced acute lung injury or acute respiratory distress syndrome (ALI/ARDS) in piglets. Material/Methods We developed ALI/ARDS models in piglets by intraperitoneal injection of paraquat (PQ). The piglets were randomly divided into three groups: small VT group (VT=6 ml/kg, n=6), middle VT group (VT=10 ml/kg, n=6), and large VT group (VT=15 ml/kg, n=6), with the positive end-expiratory pressure (PEEP) set as 10 cmH2O. The hemodynamics were monitored by pulse-indicated continuous cardiac output (PiCCO) and the airway pressure changes and blood gas analysis indexes were recorded at different time points. The pathological changes were observed by lung puncture. Results The piglets showed ALI/ARDS in 4.5±0.8 hours after PQ intraperitoneal injection. PH, PaO2 and oxygenation indexes in the three groups all decreased after modeling success compared with baseline, and PaCO2 increased significantly. PH in the small VT group decreased most obviously after ventilation for 6 hours. PaO2 and oxygenation indexes in the small VT group showed the most obvious increase after ventilation for 2 hours and were much higher than the other two groups after ventilation for 6 hours. PaCO2 increased gradually after mechanical ventilation and the small VT group showed most obvious increase. The ELWI increased obviously after ventilation for 2 hours and then the small VT group clearly decreased. PIP and plateau pressure (Pplat) in the small VT group decreased gradually and in the middle and large VT group they increased after ventilation. The lung histopathology showed that the large VT group had the most severe damage and the small VT group had only minimal damage. Conclusions Small tidal volume ventilation combined with PEEP could alleviate the acute lung injury induced by paraquat and improve oxygenation. PMID:25671690

  3. A universal definition of ARDS: the PaO2/FiO2 ratio under a standard ventilatory setting--a prospective, multicenter validation study.

    PubMed

    Villar, Jesús; Pérez-Méndez, Lina; Blanco, Jesús; Añón, José Manuel; Blanch, Lluís; Belda, Javier; Santos-Bouza, Antonio; Fernández, Rosa Lidia; Kacmarek, Robert M

    2013-04-01

    The PaO2/FiO2 is an integral part of the assessment of patients with acute respiratory distress syndrome (ARDS). The American-European Consensus Conference definition does not mandate any standardization procedure. We hypothesized that the use of PaO2/FiO2 calculated under a standard ventilatory setting within 24 h of ARDS diagnosis allows a more clinically relevant ARDS classification. We studied 452 ARDS patients enrolled prospectively in two independent, multicenter cohorts treated with protective mechanical ventilation. At the time of ARDS diagnosis, patients had a PaO2/FiO2 ≤ 200. In the derivation cohort (n = 170), we measured PaO2/FiO2 with two levels of positive end-expiratory pressure (PEEP) (≥ 5 and ≥ 10 cmH2O) and two levels of FiO2 (≥ 0.5 and 1.0) at ARDS onset and 24 h later. Dependent upon PaO2 response, patients were reclassified into three groups: mild (PaO2/FiO2 > 200), moderate (PaO2/FiO2 101-200), and severe (PaO2/FiO2 ≤ 100) ARDS. The primary outcome measure was ICU mortality. The standard ventilatory setting that reached the highest significance difference in mortality among these categories was tested in a separate cohort (n = 282). The only standard ventilatory setting that identified the three PaO2/FiO2 risk categories in the derivation cohort was PEEP ≥ 10 cmH2O and FiO2 ≥ 0.5 at 24 h after ARDS onset (p = 0.0001). Using this ventilatory setting, patients in the validation cohort were reclassified as having mild ARDS (n = 47, mortality 17 %), moderate ARDS (n = 149, mortality 40.9 %), and severe ARDS (n = 86, mortality 58.1 %) (p = 0.00001). Our method for assessing PaO2/FiO2 greatly improved risk stratification of ARDS and could be used for enrolling appropriate ARDS patients into therapeutic clinical trials.

  4. Effect of tracheal suctioning on aspiration past the tracheal tube cuff in mechanically ventilated patients

    PubMed Central

    2012-01-01

    Background This clinical study evaluated the effect of a suctioning maneuver on aspiration past the cuff during mechanical ventilation. Methods Patients intubated for less than 48 hours with a PVC-cuffed tracheal tube, under mechanical ventilation with a PEEP ≥5 cm H2O and under continuous sedation, were included in the study. At baseline the cuff pressure was set at 30 cm H2O. Then 0.5ml of blue dye diluted with 3 ml of saline was instilled into the subglottic space just above the cuff. Tracheal suctioning was performed using a 16-French suction catheter with a suction pressure of – 400 mbar. A fiberoptic bronchoscopy was performed before and after the suctioning maneuver, looking for the presence of blue dye in the folds within the cuff wall or in the trachea under the cuff. The sealing of the cuff was defined by the absence of leakage of blue dye either in the cuff wall or in the trachea under the cuff. Results Twenty-five patients were included. The size of the tracheal tube was 7-mm ID for 5 patients, 7.5-mm ID for 16 patients, and 8-mm ID for four patients. Blue dye was never seen in the trachea under the cuff before suctioning and only in one patient (4%) after the suctioning maneuver. Blue dye was observed in the folds within the cuff wall in 6 of 25 patients before suctioning and 11 of 25 after (p = 0.063). Overall, the incidence of sealing of the cuff was 76% before suctioning and 56% after (p = 0.073). Conclusions In patients intubated with a PVC-cuffed tracheal tube and under mechanical ventilation with PEEP ≥5 cm H2O and a cuff pressure set at 30 cm H2O, a single tracheal suctioning maneuver did not increase the risk of aspiration in the trachea under the cuff. Trial registration ClinicalTrials.gov, number NCT01170156 PMID:23134813

  5. Acute chlorine gas exposure produces transient inflammation and a progressive alteration in surfactant composition with accompanying mechanical dysfunction

    SciTech Connect

    Massa, Christopher B.; Scott, Pamela; Abramova, Elena; Gardner, Carol; Laskin, Debra L.; Gow, Andrew J.

    2014-07-01

    Acute Cl{sub 2} exposure following industrial accidents or military/terrorist activity causes pulmonary injury and severe acute respiratory distress. Prior studies suggest that antioxidant depletion is important in producing dysfunction, however a pathophysiologic mechanism has not been elucidated. We propose that acute Cl{sub 2} inhalation leads to oxidative modification of lung lining fluid, producing surfactant inactivation, inflammation and mechanical respiratory dysfunction at the organ level. C57BL/6J mice underwent whole-body exposure to an effective 60 ppm-hour Cl{sub 2} dose, and were euthanized 3, 24 and 48 h later. Whereas pulmonary architecture and endothelial barrier function were preserved, transient neutrophilia, peaking at 24 h, was noted. Increased expression of ARG1, CCL2, RETLNA, IL-1b, and PTGS2 genes was observed in bronchoalveolar lavage (BAL) cells with peak change in all genes at 24 h. Cl{sub 2} exposure had no effect on NOS2 mRNA or iNOS protein expression, nor on BAL NO{sub 3}{sup −} or NO{sub 2}{sup −}. Expression of the alternative macrophage activation markers, Relm-α and mannose receptor was increased in alveolar macrophages and pulmonary epithelium. Capillary surfactometry demonstrated impaired surfactant function, and altered BAL phospholipid and surfactant protein content following exposure. Organ level respiratory function was assessed by forced oscillation technique at 5 end expiratory pressures. Cl{sub 2} exposure had no significant effect on either airway or tissue resistance. Pulmonary elastance was elevated with time following exposure and demonstrated PEEP refractory derecruitment at 48 h, despite waning inflammation. These data support a role for surfactant inactivation as a physiologic mechanism underlying respiratory dysfunction following Cl{sub 2} inhalation. - Highlights: • Effect of 60 ppm*hr Cl{sub 2} gas on lung inflammation and mechanical function examined. • Pulmonary inflammation is transient and minor.

  6. An estimation of mechanical stress on alveolar walls during repetitive alveolar reopening and closure.

    PubMed

    Chen, Zheng-Long; Song, Yuan-Lin; Hu, Zhao-Yan; Zhang, Su; Chen, Ya-Zhu

    2015-08-01

    Alveolar overdistension and mechanical stresses generated by repetitive opening and closing of small airways and alveoli have been widely recognized as two primary mechanistic factors that may contribute to the development of ventilator-induced lung injury. A long-duration exposure of alveolar epithelial cells to even small, shear stresses could lead to the changes in cytoskeleton and the production of inflammatory mediators. In this paper, we have made an attempt to estimate in situ the magnitudes of mechanical stresses exerted on the alveolar walls during repetitive alveolar reopening by using a tape-peeling model of McEwan and Taylor (35). To this end, we first speculate the possible ranges of capillary number (Ca) ≡ μU/γ (a dimensionless combination of surface tension γ, fluid viscosity μ, and alveolar opening velocity U) during in vivo alveolar opening. Subsequent calculations show that increasing respiratory rate or inflation rate serves to increase the values of mechanical stresses. For a normal lung, the predicted maximum shear stresses are <15 dyn/cm(2) at all respiratory rates, whereas for a lung with elevated surface tension or viscosity, the maximum shear stress will notably increase, even at a slow respiratory rate. Similarly, the increased pressure gradients in the case of elevated surface or viscosity may lead to a pressure drop >300 dyn/cm(2) across a cell, possibly inducing epithelial hydraulic cracks. In addition, we have conceived of a geometrical model of alveolar opening to make a prediction of the positive end-expiratory pressure (PEEP) required to splint open a collapsed alveolus, which as shown by our results, covers a wide range of pressures, from several centimeters to dozens of centimeters of water, strongly depending on the underlying pulmonary conditions. The establishment of adequate regional ventilation-to-perfusion ratios may prevent recruited alveoli from reabsorption atelectasis and accordingly, reduce the required levels of

  7. New method of preoxygenation for orotracheal intubation in patients with hypoxaemic acute respiratory failure in the intensive care unit, non-invasive ventilation combined with apnoeic oxygenation by high flow nasal oxygen: the randomised OPTINIV study protocol

    PubMed Central

    Jaber, Samir; Molinari, Nicolas; De Jong, Audrey

    2016-01-01

    Introduction Tracheal intubation in the intensive care unit (ICU) is associated with severe life-threatening complications including severe hypoxaemia. Preoxygenation before intubation has been recommended in order to decrease such complications. Non-invasive ventilation (NIV)-assisted preoxygenation allows increased oxygen saturation during the intubation procedure, by applying a positive end-expiratory pressure (PEEP) to prevent alveolar derecruitment. However, the NIV mask has to be taken off after preoxygenation to allow the passage of the tube through the mouth. The patient with hypoxaemia does not receive oxygen during this period, at risk of major hypoxaemia. High-flow nasal cannula oxygen therapy (HFNC) has a potential for apnoeic oxygenation during the apnoea period following the preoxygenation with NIV. Whether application of HFNC combined with NIV is more effective at reducing oxygen desaturation during the intubation procedure compared with NIV alone for preoxygenation in patients with hypoxaemia in the ICU with acute respiratory failure remains to be established. Methods and analysis The HFNC combined to NIV for decreasing oxygen desaturation during the intubation procedure in patients with hypoxaemia in the ICU (OPTINIV) trial is an investigator-initiated monocentre randomised controlled two-arm trial with assessor-blinded outcome assessment. The OPTINIV trial randomises 50 patients with hypoxaemia requiring orotracheal intubation for acute respiratory failure to receive NIV (pressure support=10, PEEP=5, fractional inspired oxygen (FiO2)=100%) combined with HFNC (flow=60 L/min, FiO2=100%, interventional group) or NIV alone (reference group) for preoxygenation. The primary outcome is lowest oxygen saturation during the intubation procedure. Secondary outcomes are intubation-related complications, quality of preoxygenation and ICU mortality. Ethics and dissemination The study project has been approved by the appropriate ethics committee (CPP Sud

  8. The clinical practice guideline for the management of ARDS in Japan.

    PubMed

    Hashimoto, Satoru; Sanui, Masamitsu; Egi, Moritoki; Ohshimo, Shinichiro; Shiotsuka, Junji; Seo, Ryutaro; Tanaka, Ryoma; Tanaka, Yu; Norisue, Yasuhiro; Hayashi, Yoshiro; Nango, Eishu

    2017-01-01

    The Japanese Society of Respiratory Care Medicine and the Japanese Society of Intensive Care Medicine provide here a clinical practice guideline for the management of adult patients with ARDS in the ICU. The guideline was developed applying the GRADE system for performing robust systematic reviews with plausible recommendations. The guideline consists of 13 clinical questions mainly regarding ventilator settings and drug therapies (the last question includes 11 medications that are not approved for clinical use in Japan). The recommendations for adult patients with ARDS include: we suggest against early tracheostomy (GRADE 2C), we suggest using NPPV for early respiratory management (GRADE 2C), we recommend the use of low tidal volumes at 6-8 mL/kg (GRADE 1B), we suggest setting the plateau pressure at 30cmH20 or less (GRADE2B), we suggest using PEEP within the range of plateau pressures less than or equal to 30cmH2O, without compromising hemodynamics (Grade 2B), and using higher PEEP levels in patients with moderate to severe ARDS (Grade 2B), we suggest using protocolized methods for liberation from mechanical ventilation (Grade 2D), we suggest prone positioning especially in patients with moderate to severe respiratory dysfunction (GRADE 2C), we suggest against the use of high frequency oscillation (GRADE 2C), we suggest the use of neuromuscular blocking agents in patients requiring mechanical ventilation under certain circumstances (GRADE 2B), we suggest fluid restriction in the management of ARDS (GRADE 2A), we do not suggest the use of neutrophil elastase inhibitors (GRADE 2D), we suggest the administration of steroids, equivalent to methylprednisolone 1-2mg/kg/ day (GRADE 2A), and we do not recommend other medications for the treatment of adult patients with ARDS (GRADE1B; inhaled/intravenous β2 stimulants, prostaglandin E1, activated protein C, ketoconazole, and lisofylline, GRADE 1C; inhaled nitric oxide, GRADE 1D; surfactant, GRADE 2B; granulocyte

  9. Stroke volume changes induced by a recruitment maneuver predict fluid responsiveness in patients with protective ventilation in the operating theater

    PubMed Central

    De Broca, Bruno; Garnier, Jeremie; Fischer, Marc-Olivier; Archange, Thomas; Marc, Julien; Abou-Arab, Osama; Dupont, Hervé; Lorne, Emmanuel; Guinot, Pierre-grégoire

    2016-01-01

    Abstract During abdominal surgery, the use of protective ventilation with a low tidal volume, positive expiratory pressure (PEEP) and recruitment maneuvers (RMs) may limit the applicability of dynamic preload indices. The objective of the present study was to establish whether or not the variation in stroke volume (SV) during an RM could predict fluid responsiveness. We prospectively included patients receiving protective ventilation (tidal volume: 6 mL kg−1, PEEP: 5–7 cmH2O; RMs). Hemodynamic variables, such as heart rate, arterial pressure, SV, cardiac output (CO), respiratory variation in SV (ΔrespSV) and pulse pressure (ΔrespPP), and the variation in SV (ΔrecSV) as well as pulse pressure (ΔrecPP) during an RM were measured at baseline, at the end of the RM, and after fluid expansion. Responders were defined as patients with an SV increase of at least 15% after infusion of 500 mL of crystalloid solution. Thirty-seven (62%) of the 60 included patients were responders. Responders and nonresponders differed significantly in terms of the median ΔrecSV (26% [19–37] vs 10% [4–12], respectively; P < 0.0001). A ΔrecSV value more than 16% predicted fluid responsiveness with an area under the receiver-operating characteristic curve (AU) of 0.95 (95% confidence interval [CI]: 0.91–0.99; P < 0.0001) and a narrow gray zone between 15% and 17%. The area under the curve values for ΔrecPP and ΔrespSV were, respectively, 0.81 (95%CI: 0.7–0.91; P = 0.0001) and 0.80 (95%CI: 0.70–0.94; P < 0.0001). ΔrespPP did not predict fluid responsiveness. During abdominal surgery with protective ventilation, a ΔrecSV value more than 16% accurately predicted fluid responsiveness and had a narrow gray zone (between 15% and 17%). ΔrecPP and ΔrespSV (but not ΔrespPP) were also predictive. PMID:27428237

  10. Stroke volume changes induced by a recruitment maneuver predict fluid responsiveness in patients with protective ventilation in the operating theater.

    PubMed

    De Broca, Bruno; Garnier, Jeremie; Fischer, Marc-Olivier; Archange, Thomas; Marc, Julien; Abou-Arab, Osama; Dupont, Hervé; Lorne, Emmanuel; Guinot, Pierre-Grégoire

    2016-07-01

    During abdominal surgery, the use of protective ventilation with a low tidal volume, positive expiratory pressure (PEEP) and recruitment maneuvers (RMs) may limit the applicability of dynamic preload indices. The objective of the present study was to establish whether or not the variation in stroke volume (SV) during an RM could predict fluid responsiveness.We prospectively included patients receiving protective ventilation (tidal volume: 6 mL kg, PEEP: 5-7 cmH2O; RMs). Hemodynamic variables, such as heart rate, arterial pressure, SV, cardiac output (CO), respiratory variation in SV (ΔrespSV) and pulse pressure (ΔrespPP), and the variation in SV (ΔrecSV) as well as pulse pressure (ΔrecPP) during an RM were measured at baseline, at the end of the RM, and after fluid expansion. Responders were defined as patients with an SV increase of at least 15% after infusion of 500 mL of crystalloid solution.Thirty-seven (62%) of the 60 included patients were responders. Responders and nonresponders differed significantly in terms of the median ΔrecSV (26% [19-37] vs 10% [4-12], respectively; P < 0.0001). A ΔrecSV value more than 16% predicted fluid responsiveness with an area under the receiver-operating characteristic curve (AU) of 0.95 (95% confidence interval [CI]: 0.91-0.99; P < 0.0001) and a narrow gray zone between 15% and 17%. The area under the curve values for ΔrecPP and ΔrespSV were, respectively, 0.81 (95%CI: 0.7-0.91; P = 0.0001) and 0.80 (95%CI: 0.70-0.94; P < 0.0001). ΔrespPP did not predict fluid responsiveness.During abdominal surgery with protective ventilation, a ΔrecSV value more than 16% accurately predicted fluid responsiveness and had a narrow gray zone (between 15% and 17%). ΔrecPP and ΔrespSV (but not ΔrespPP) were also predictive.

  11. How do different brands of size 1 laryngeal mask airway compare with face mask ventilation in a dedicated laryngeal mask airway teaching manikin?

    PubMed

    Tracy, Mark Brian; Priyadarshi, Archana; Goel, Dimple; Lowe, Krista; Huvanandana, Jacqueline; Hinder, Murray

    2017-08-11

    International neonatal resuscitation guidelines recommend the use of laryngeal mask airway (LMA) with newborn infants (≥34 weeks' gestation or >2 kg weight) when bag-mask ventilation (BMV) or tracheal intubation is unsuccessful. Previous publications do not allow broad LMA device comparison. To compare delivered ventilation of seven brands of size 1 LMA devices with two brands of face mask using self-inflating bag (SIB). 40 experienced neonatal staff provided inflation cycles using SIB with positive end expiratory pressure (PEEP) (5 cmH2O) to a specialised newborn/infant training manikin randomised for each LMA and face mask. All subjects received prior education in LMA insertion and BMV. 12 415 recorded inflations for LMAs and face masks were analysed. Leak detected was lowest with i-gel brand, with a mean of 5.7% compared with face mask (triangular 42.7, round 35.7) and other LMAs (45.5-65.4) (p<0.001). Peak inspiratory pressure was higher with i-gel, with a mean of 28.9 cmH2O compared with face mask (triangular 22.8, round 25.8) and other LMAs (14.3-22.0) (p<0.001). PEEP was higher with i-gel, with a mean of 5.1 cmH2O compared with face mask (triangular 3.0, round 3.6) and other LMAs (0.6-2.6) (p<0.001). In contrast to other LMAs examined, i-gel had no insertion failures and all users found i-gel easy to use. This study has shown dramatic performance differences in delivered ventilation, mask leak and ease of use among seven different brands of LMA tested in a manikin model. This coupled with no partial or complete insertion failures and ease of use suggests i-gel LMA may have an expanded role with newborn resuscitation as a primary resuscitation device. © 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.

  12. An attempt to validate the modification of the American-European consensus definition of acute lung injury/acute respiratory distress syndrome by the Berlin definition in a university hospital.

    PubMed

    Hernu, R; Wallet, F; Thiollière, F; Martin, O; Richard, J C; Schmitt, Z; Wallon, G; Delannoy, B; Rimmelé, T; Démaret, C; Magnin, C; Vallin, H; Lepape, A; Baboi, L; Argaud, L; Piriou, V; Allaouchiche, B; Aubrun, F; Bastien, O; Lehot, J J; Ayzac, L; Guérin, C

    2013-12-01

    The Berlin definition for acute respiratory distress syndrome (ARDS) is a new proposal for changing the American-European consensus definition but has not been assessed prospectively as yet. In the present study, we aimed to determine (1) the prevalence and incidence of ARDS with both definitions, and (2) the initial characteristics of patients with ARDS and 28-day mortality with the Berlin definition. We performed a 6-month prospective observational study in the ten adult ICUs affiliated to the Public University Hospital in Lyon, France, from March to September 2012. Patients under invasive or noninvasive mechanical ventilation, with PaO2/FiO2 <300 mmHg regardless of the positive end-expiratory pressure (PEEP) level, and acute onset of new or increased bilateral infiltrates or opacities on chest X-ray were screened from ICU admission up to discharge. Patients with cardiogenic pulmonary edema were excluded. Patients were further classified into specific categories by using the American-European Consensus Conference and the Berlin definition criteria. The complete data set was measured at the time of inclusion. Patient outcome was measured at day 28 after inclusion. During the study period 3,504 patients were admitted and 278 fulfilled the American-European Consensus Conference criteria. Among them, 18 (6.5 %) did not comply with the Berlin criterion PEEP ≥ 5 cmH2O and 20 (7.2 %) had PaO2/FiO2 ratio ≤200 while on noninvasive ventilation. By using the Berlin definition in the remaining 240 patients (n = 42 mild, n = 123 moderate, n = 75 severe), the overall prevalence was 6.85 % and it was 1.20, 3.51, and 2.14 % for mild, moderate, and severe ARDS, respectively (P > 0.05 between the three groups). The incidence of ARDS amounted to 32 per 100,000 population per year, with values for mild, moderate, and severe ARDS of 5.6, 16.3, and 10 per 100,000 population per year, respectively (P < 0.05 between the three groups). The 28-day mortality was 35.0 %. It amounted to

  13. Vascular pedicle width in acute lung injury: correlation with intravascular pressures and ability to discriminate fluid status

    PubMed Central

    2011-01-01

    Introduction Conservative fluid management in patients with acute lung injury (ALI) increases time alive and free from mechanical ventilation. Vascular pedicle width (VPW) is a non-invasive measurement of intravascular volume status. The VPW was studied in ALI patients to determine the correlation between VPW and intravascular pressure measurements and whether VPW could predict fluid status. Methods This retrospective cohort study involved 152 patients with ALI enrolled in the Fluid and Catheter Treatment Trial (FACTT) from five NHLBI ARDS (Acute Respiratory Distress Syndrome) Network sites. VPW and central venous pressure (CVP) or pulmonary artery occlusion pressure (PAOP) from the first four study days were correlated. The relationships between VPW, positive end-expiratory pressure (PEEP), cumulative fluid balance, and PAOP were also evaluated. Receiver operator characteristic (ROC) curves were used to determine the ability of VPW to detect PAOP <8 mmHg and PAOP ≥18 mm Hg. Results A total of 71 and 152 patients provided 118 and 276 paired VPW/PAOP and VPW/CVP measurements, respectively. VPW correlated with PAOP (r = 0.41; P < 0.001) and less well with CVP (r = 0.21; P = 0.001). In linear regression, VPW correlated with PAOP 1.5-fold better than cumulative fluid balance and 2.5-fold better than PEEP. VPW discriminated achievement of PAOP <8 mm Hg (AUC = 0.73; P = 0.04) with VPW ≤67 mm demonstrating 71% sensitivity (95% CI 30 to 95%) and 68% specificity (95% CI 59 to 75%). For discriminating a hydrostatic component of the edema (that is, PAOP ≥18 mm Hg), VPW ≥72 mm demonstrated 61.4% sensitivity (95% CI 47 to 74%) and 61% specificity (49 to 71%) (area under the curve (AUC) 0.69; P = 0.001). Conclusions VPW correlates with PAOP better than CVP in patients with ALI. Due to its only moderate sensitivity and specificity, the ability of VPW to discriminate fluid status in patients with acute lung injury is limited and should only be considered when intravascular

  14. Lung-protective Ventilation in Patients with Brain Injury: A Multicenter Cross-sectional Study and Questionnaire Survey in China

    PubMed Central

    Luo, Xu-Ying; Hu, Ying-Hong; Cao, Xiang-Yuan; Kang, Yan; Liu, Li-Ping; Wang, Shou-Hong; Yu, Rong-Guo; Yu, Xiang-You; Zhang, Xia; Li, Bao-Shan; Ma, Zeng-Xiang; Weng, Yi-Bing; Zhang, Heng; Chen, De-Chang; Chen, Wei; Chen, Wen-Jin; Chen, Xiu-Mei; Du, Bin; Duan, Mei-Li; Hu, Jin; Huang, Yun-Feng; Jia, Gui-Jun; Li, Li-Hong; Liang, Yu-Min; Qin, Bing-Yu; Wang, Xian-Dong; Xiong, Jian; Yan, Li-Mei; Yang, Zheng-Ping; Dong, Chen-Ming; Wang, Dong-Xin; Zhan, Qing-Yuan; Fu, Shuang-Lin; Zhao, Lin; Huang, Qi-Bing; Xie, Ying-Guang; Huang, Xiao-Bo; Zhang, Guo-Bin; Xu, Wang-Bin; Xu, Yuan; Liu, Ya-Ling; Zhao, He-Ling; Sun, Rong-Qing; Sun, Ming; Cheng, Qing-Hong; Qu, Xin; Yang, Xiao-Feng; Xu, Ming; Shi, Zhong-Hua; Chen, Han; He, Xuan; Yang, Yan-Lin; Chen, Guang-Qiang; Sun, Xiu-Mei; Zhou, Jian-Xin

    2016-01-01

    Background: Over the years, the mechanical ventilation (MV) strategy has changed worldwide. The aim of the present study was to describe the ventilation practices, particularly lung-protective ventilation (LPV), among brain-injured patients in China. Methods: This study was a multicenter, 1-day, cross-sectional study in 47 Intensive Care Units (ICUs) across China. Mechanically ventilated patients (18 years and older) with brain injury in a participating ICU during the time of the study, including traumatic brain injury, stroke, postoperation with intracranial tumor, hypoxic-ischemic encephalopathy, intracranial infection, and idiopathic epilepsy, were enrolled. Demographic data, primary diagnoses, indications for MV, MV modes and settings, and prognoses on the 60th day were collected. Multivariable logistic analysis was used to assess factors that might affect the use of LPV. Results: A total of 104 patients were enrolled in the present study, 87 (83.7%) of whom were identified with severe brain injury based on a Glasgow Coma Scale ≤8 points. Synchronized intermittent mandatory ventilation (SIMV) was the most frequent ventilator mode, accounting for 46.2% of the entire cohort. The median tidal volume was set to 8.0 ml/kg (interquartile range [IQR], 7.0–8.9 ml/kg) of the predicted body weight; 50 (48.1%) patients received LPV. The median positive end-expiratory pressure (PEEP) was set to 5 cmH2O (IQR, 5–6 cmH2O). No PEEP values were higher than 10 cmH2O. Compared with partially mandatory ventilation, supportive and spontaneous ventilation practices were associated with LPV. There were no significant differences in mortality and MV duration between patients subjected to LPV and those were not. Conclusions: Among brain-injured patients in China, SIMV was the most frequent ventilation mode. Nearly one-half of the brain-injured patients received LPV. Patients under supportive and spontaneous ventilation were more likely to receive LPV. Trial Registration: Clinical

  15. Effect of a lung protective strategy for organ donors on eligibility and availability of lungs for transplantation: a randomized controlled trial.

    PubMed

    Mascia, Luciana; Pasero, Daniela; Slutsky, Arthur S; Arguis, M Jose; Berardino, Maurizio; Grasso, Salvatore; Munari, Marina; Boifava, Silvia; Cornara, Giuseppe; Della Corte, Francesco; Vivaldi, Nicoletta; Malacarne, Paolo; Del Gaudio, Paolo; Livigni, Sergio; Zavala, Elisabeth; Filippini, Claudia; Martin, Erica L; Donadio, Pier Paolo; Mastromauro, Ilaria; Ranieri, V Marco

    2010-12-15

    Many potential donor lungs deteriorate between the time of brain death and evaluation for transplantation suitability, possibly because of the ventilatory strategy used after brain death. To test whether a lung protective strategy increases the number of lungs available for transplantation. Multicenter randomized controlled trial of patients with beating hearts who were potential organ donors conducted at 12 European intensive care units from September 2004 to May 2009 in the Protective Ventilatory Strategy in Potential Lung Donors Study. Interventions Potential donors were randomized to the conventional ventilatory strategy (with tidal volumes of 10-12 mL/kg of predicted body weight, positive end-expiratory pressure [PEEP] of 3-5 cm H(2)O, apnea tests performed by disconnecting the ventilator, and open circuit for airway suction) or the protective ventilatory strategy (with tidal volumes of 6-8 mL/kg of predicted body weight, PEEP of 8-10 cm H(2)O, apnea tests performed by using continuous positive airway pressure, and closed circuit for airway suction). The number of organ donors meeting eligibility criteria for harvesting, number of lungs harvested, and 6-month survival of lung transplant recipients. The trial was stopped after enrolling 118 patients (59 in the conventional ventilatory strategy and 59 in the protective ventilatory strategy) because of termination of funding. The number of patients who met lung donor eligibility criteria after the 6-hour observation period was 32 (54%) in the conventional strategy vs 56 (95%) in the protective strategy (difference of 41% [95% confidence interval {CI}, 26.5% to 54.8%]; P <.001). The number of patients in whom lungs were harvested was 16 (27%) in the conventional strategy vs 32 (54%) in the protective strategy (difference of 27% [95% CI, 10.0% to 44.5%]; P = .004). Six-month survival rates did not differ between recipients who received lungs from donors ventilated with the conventional strategy compared with the

  16. Altitudinal distribution and advertisement call of Colostethus latinasus (Amphibia: Dendrobatidae), endemic species from eastern Panama and type species of Colostethus , with a molecular assessment of similar sympatric species.

    PubMed

    Ibáñez, Roberto D; Griffith, Edgardo J; Lips, Karen R; Crawford, Andrew J

    2017-04-12

    We conducted a molecular assessment of Colostethus-like frogs along an elevational gradient in the Serranía de Pirre, above Santa Cruz de Cana, eastern Panama, aiming to establish their species identity and to determine the altitudinal distribution of C. latinasus. Our findings confirm the view of C. latinasus as an endemic species restricted to the highlands of this mountain range, i.e., 1350-1475 m.a.s.l., considered to be type locality of this species. We described the advertisement call of C. latinasus that consists of a series of 4-18 single, short and relatively loud "peep"-like notes given in rapid succession, and its spectral and temporal features were compared with calls of congeneric species. For the first time, DNA sequences from C. latinasus were obtained, since previously reported sequences were based on misidentified specimens. This is particularly important because C. latinasus is the type species of Colostethus, a genus considered paraphyletic according to recent phylogenetic analyses based on molecular data.

  17. Examining gender based violence and abuse among Liberian school students in four counties: An exploratory study.

    PubMed

    Postmus, Judy L; Hoge, Gretchen L; Davis, Rebecca; Johnson, Laura; Koechlein, Elizabeth; Winter, Samantha

    2015-06-01

    The purpose of this article is to uncover the extent of sexual gender based violence (GBV) experienced by a convenience sample of students from select counties in Liberia and to understand the disclosure experiences of those victims willing to come forward. Girls (n=758) and boys (n=1,100) were asked about their sexual GBV experiences including their disclosure experiences, if applicable. Results indicated that sexual violation (i.e., peeping or inappropriate touching) was found among both girls and boys. Sexual coercion (i.e., forced sex) was more prevalent than transactional sex (i.e., trading sex for grades or money). Both sexual coercion and transactional sex were reported by more girls than boys, yet the rates for the most severe form of sexual violence (i.e., sexual coercion) were high for both girls (30%) and boys (22%). When students were asked if they told anyone, 38% reported that they did disclose their experiences. This study contributes to a small but growing body of research to document the prevalence and types of sexual violence against children in Liberia. Consistent with other studies, the evidence shows that sexual violence against boys and girls is occurring at alarming rates.

  18. Independent lung ventilation combined with HFOV for a patient suffering from tracheo-gastric roll fistula.

    PubMed

    Ichinose, Maki; Sakai, Hiroaki; Miyazaki, Ikuo; Muraoka, Akihiro; Aizawa, Miyuki; Igarashi, Kaigen; Okazaki, Atsushi

    2008-01-01

    This case report describes the difficult respiratory management of an esophageal cancer patient with acute respiratory distress syndrome (ARDS) and systemic inflammatory response syndrome (SIRS) caused by a postoperative tracheogastric roll fistula. A single-lumen tracheal tube could not seal the fistula, and therefore a double-lumen tracheal tube (DLT) for the left side was used. Although the proximal cuff of the DLT failed to seal the fistula, independent lung ventilation (ILV) improved blood gas levels. During right thoracotomy, the left lung was ventilated conventionally with 5 cmH2O positive end-expiratory pressure (PEEP), and in addition, high-frequency oscillation ventilation (HFOV) to the right lung was employed. This combination allowed the maintenance of adequate oxygenation, and the HFOV to the right lung decreased the PaCO2 level during surgery without interruption of the surgical field. These techniques provided the opportunity to successfully remove a necrotic gastric roll and achieve closure of the fistula using an intercostal muscle flap. This report documents and discusses the difficulty of performing appropriate anesthetic management of a patient with these complex complications after esophageal surgery.

  19. Pulmonary and extrapulmonary acute respiratory distress syndrome: are they different?

    PubMed

    Garcia, Cristiane S N Baez; Pelosi, Paolo; Rocco, Patricia R M

    2008-06-01

    The pathogenesis of acute respiratory distress syndrome (ARDS) has been described by the presence of direct (pulmonary) and/or indirect (extrapulmonary) insult to the lung parenchyma. Evidence indicates that the pathophysiology of ARDS may differ according to the type of primary insult. This article presents a brief overview of differences between pulmonary and extrapulmonary ARDS, and discusses the interactions between morpho-functional aspects and response to differents therapies, both in experimental and clinical studies. This systematic review included clinical and experimental ARDS studies found in MedLine and SciElo databases in the last 20 years. Many researchers acknowledge that experimental pulmonary and extrapulmonary ARDS are not identical with regard to morpho-functional aspects, the response to positive end-expiratory pressure (PEEP), recruitment manoeuvre, prone position and other adjunctive therapies. However, contradictory results have been reported in different clinical studies, which could be attributed to the difficulty of classifying ARDS in one or the other category, and to the assurance regarding the onset, phase and severity of ARDS in all patients. Heterogeneous ARDS patients are still considered as belonging to one syndrome, and are therefore treated in a similar manner. Thus, it is important to understand the pathophysiology of pulmonary and extrapulmonary ARDS in an attempt to better treat these patients.

  20. Assessing pulmonary function in acute respiratory insufficiency: a clinical charting sheet.

    PubMed

    Peirce, E C

    1987-07-01

    A sheet to chart the clinical respiratory variables relevant to acute respiratory insufficiency (ARI) therapy is presented. The chart permits plotting shunt fraction (Qsp/Qt) and efficiency (E or 1--Qsp/Qt) vs. load (L). L is the volume of oxygen (combined and dissolved) that would be exchanged in the lung per minute, if venous blood became fully equilibrated with alveolar gas. L relates cardiac output (Qt), hemoglobin concentration, alveolar oxygen tension, venous oxygen saturation and tension, and the oxygen-hemoglobin combining and oxygen solubility constants. Oxygen consumption (VO2) isopleths are added to the sheet (VO2 = L X E). Qt, VO2, and hence L are indexed per m2 (body surface area), and the approximate normal VO2 range is indicated. Using this sheet hopefully simplifies the correlation of complex pulmonary oxygen exchange data and enhances information recognition and analysis. It provides special help in determining the optimal PEEP in difficult ARI cases. To illustrate its use, a case is detailed.

  1. Respiratory monitoring with electrical impedance tomography for lung protective ventilation and alveolar recruitment maneuver in a patient with a single lung transplant and early graft dysfunction.

    PubMed

    Romero, A; Alonso, B; Latorre, I; García, J

    2016-01-01

    A case is presented on a patient who underwent left single lung transplantation for emphysema type COPD. There was early graft dysfunction gradeiii during the immediate postoperative period, which required the implantation of an extracorporeal membrane oxygenator (ECMO). Respirator ventilatory parameters were adjusted to avoid lung distension, low tidal volume (Vc) (280ml), high respiratory rates (20rpm), and a positive pressure at end expiration (PEEP) level of 8cmH2O. On monitoring the pulmonary tidal volume distribution by bedside electrical impedance tomography (EIT), it was noted that most of the tidal volume was distributed in the native lung emphysema. An alveolar recruitment manoeuvre was performed, under control of the EIT, that enabled the current volume and distribution and the pressures required to ventilate the transplanted lung to be observed. Copyright © 2015 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  2. Double and target asymmetries for the e p ->e' p 0̂ production

    NASA Astrophysics Data System (ADS)

    Biselli, Angela

    2006-04-01

    An extensive experimental program to measure the spin structure of the nucleons is carried out in Hall B with the CLAS detector at Jefferson Lab using a polarized electron beam incident on a polarized target. Spin degrees of freedom offer the possibility to test, in an independent way, existing models of resonance electroproduction. The present analysis selects the exclusive channel p(e,e',p)0̂ from data taken in 2000-2001, to extract single and double asymmetries in a Q^2 range from 0.2 to 0.75 GeV^2 and a W range from 1.1 to 1.6 GeV. Results of the asymmetries will be presented as a function of the center of mass decay angles of the 0̂ and compared with the unitary isobar model MAID [1], the dynamic model by Sato and Lee [2] and the dynamic model DMT [3]. [1] D. Drechsel et al., Nucl. Phys. A645 (1999) 145-174 [2] H. Lee, Nucl. Phys. A513 (1990) 511 [3] S. S. Kamalov, Phys. Lett. B 522 (2001) 522

  3. The vocal repertoire of the African Penguin (Spheniscus demersus): structure and function of calls.

    PubMed

    Favaro, Livio; Ozella, Laura; Pessani, Daniela

    2014-01-01

    The African Penguin (Spheniscus demersus) is a highly social and vocal seabird. However, currently available descriptions of the vocal repertoire of African Penguin are mostly limited to basic descriptions of calls. Here we provide, for the first time, a detailed description of the vocal behaviour of this species by collecting audio and video recordings from a large captive colony. We combine visual examinations of spectrograms with spectral and temporal acoustic analyses to determine vocal categories. Moreover, we used a principal component analysis, followed by signal classification with a discriminant function analysis, for statistical validation of the vocalisation types. In addition, we identified the behavioural contexts in which calls were uttered. The results show that four basic vocalisations can be found in the vocal repertoire of adult African Penguin, namely a contact call emitted by isolated birds, an agonistic call used in aggressive interactions, an ecstatic display song uttered by single birds, and a mutual display song vocalised by pairs, at their nests. Moreover, we identified two distinct vocalisations interpreted as begging calls by nesting chicks (begging peep) and unweaned juveniles (begging moan). Finally, we discussed the importance of specific acoustic parameters in classifying calls and the possible use of the source-filter theory of vocal production to study penguin vocalisations.

  4. [Anesthetic management of a patient with transfusion-related acute lung injury (TRALI)].

    PubMed

    Sakata, Yuko; Wada, Hiroki; Oshima, Takashi; Aramaki, Yoshihiko; Kikuta, Yoshinori; Iwasaki, Yasuji

    2008-08-01

    Transfusion-related acute lung injury (TRALI) is characterized by pulmonary edema and hypoxemia within 6 hours of transfusion in the absence of other causes of acute lung injury or circulatory overload and is now considered the leading cause of transfusion-related death. We report a female patient who showed hypoxemia after transfusion without any other causes of acute lung injury. The patient is a 43-year-old woman, who received emergency transurethral hemostasis for bladder hemorrhage with hematuria and low hemoglobin concentration (3.2 g x dl(-1)). General anesthesia was maintained with sevoflurane, remifentanil, and vecuronium. Two units of RBC were transfused during operation. Since she showed high blood pressure, tachycardia, and a painful expression after operation, we extubated her. Although we gave her O2 6 l x min(-1) after extubation, she showed low oxygen saturation (90%), thus we started bag-mask ventilation. However, she complained of dyspnea and the chest X-ray revealed bilateral diffuse pulmonary edema following hypoxemia (80%). Thus we inserted endotracheal tube and started positive pressure assist ventilation. The next day, hypoxemia was improved under PEEP therapy. The anti-HLA antibody in the transfused plasma was positive. We conclude that the early recognition and management of TRALI is essential during and after operation.

  5. Pulmonar recruitment in acute respiratory distress syndrome. What is the best strategy?

    PubMed

    Santos, Cíntia Lourenço; Samary, Cynthia dos Santos; Fiorio Júnior, Pedro Laurindo; Santos, Bruna Lourenço; Schanaider, Alberto

    2015-01-01

    Supporting patients with acute respiratory distress syndrome (ARDS), using a protective mechanical ventilation strategy characterized by low tidal volume and limitation of positive end-expiratory pressure (PEEP) is a standard practice in the intensive care unit. However, these strategies can promote lung de-recruitment, leading to the cyclic closing and reopening of collapsed alveoli and small airways. Recruitment maneuvers (RM) can be used to augment other methods, like positive end-expiratory pressure and positioning, to improve aerated lung volume. Clinical practice varies widely, and the optimal method and patient selection for recruitment maneuvers have not been determined, considerable uncertainty remaining regarding the appropriateness of RM. This review aims to discuss recent findings about the available types of RM, and compare the effectiveness, indications and adverse effects among them, as well as their impact on morbidity and mortality in ARDS patients. Recent developments include experimental and clinical evidence that a stepwise extended recruitment maneuver may cause an improvement in aerated lung volume and decrease the biological impact seen with the traditionally used sustained inflation, with less adverse effects. Prone positioning can reduce mortality in severe ARDS patients and may be an useful adjunct to recruitment maneuvers and advanced ventilatory strategies, such noisy ventilation and BIVENT, which have been useful in providing lung recruitment.

  6. [Cardiorespiratory monitoring in the diagnosis and therapy of patients with adult respiratory distress syndrome].

    PubMed

    Pilas, V; Bilić, A; Vranjković, S

    1989-01-01

    In thirty-six patients, meeting clinical criteria for the diagnosis of ARDS, findings of pulmonary functions and results of invasive hemodynamic monitoring have been separately evaluated and compared with normal values. The majority of patients presented with tachypnea having breathing frequency greater than 30/min, vital capacity less than 20 ml/kg body weight, effective pulmonary compliance less than 25 ml/cm H2O, VD/VT greater than 0.6 and D-L shunt greater than 20%. Pulmonary capillary pressure was normal in most patients and pulmonary artery mean pressure and pulmonary vasculary resistance increased. The authors believe that diagnosis of ARDS can be established with greater reliability by use of more complex pulmonary function testing and hemodynamic investigations. An invasive hemodynamic monitoring using a Swan-Ganz catheter gives irreplaceable data for diagnostic and therapeutic decisions in patients with ARDS. It enables an accurate hydration of patients, correct use of diuretics and vasoactive drugs and it is especially useful in controlled application of ventilators and PEEP.

  7. High-flow nasal oxygen therapy and noninvasive ventilation in the management of acute hypoxemic respiratory failure.

    PubMed

    Frat, Jean-Pierre; Coudroy, Rémi; Marjanovic, Nicolas; Thille, Arnaud W

    2017-07-01

    High-flow nasal cannula (HFNC) oxygen therapy is a recent technique delivering a high flow of heated and humidified gas. HFNC is simpler to use and apply than noninvasive ventilation (NIV) and appears to be a good alternative treatment for hypoxemic acute respiratory failure (ARF). HFNC is better tolerated than NIV, delivers high fraction of inspired oxygen (FiO2), generates a low level of positive pressure and provides washout of dead space in the upper airways, thereby improving mechanical pulmonary properties and unloading inspiratory muscles during ARF. A recent multicenter randomized controlled trial showed benefits of HFNC concerning mortality and intubation in severe patients with hypoxemic ARF. In management of patients with hypoxemic ARF, NIV results have been conflicting. Despite improved oxygenation, NIV delivered with face mask may generate high tidal volumes and subsequent ventilator-induced lung injury. An approach applying NIV with a helmet, high levels of positive end-expiratory pressure (PEEP) and low pressure support (PS) levels seems to open new opportunities in patients with hypoxemic ARF. However, a large-scale randomized controlled study is needed to assess and compare this approach with HFNC.

  8. [Anesthetic management of massive endobronchial hemorrhage after pulmonary embolectomy].

    PubMed

    Nakayama, Shin; Miyabe, Masayuki; Tabata, Kouya; Toyooka, Hidenori

    2003-08-01

    We report a case of massive endobronchial hemorrhage after pulmonary embolectomy. A 63-year-old woman underwent emergency pulmonary embolectomy with cardiopulmonary bypass (CPB). During partial CPB, we found massive blood gushing out from the endotracheal tube. Approximately 2,000 ml of blood was aspirated in 10 minutes. To ensure adequate oxygenation, emergent percutaneous cardiopulmonary support system (PCPS) was started. After neutralization of heparin and the institution of 10 cmH2O of positive end-expiratory pressure, the bleeding diminished. Institution of PCPS allows performance of unhurried bronchoscopy to identify the actual bleeding point and to lavage the airway. In addition to this management, we administrated steroids and neutrophil elastase inhibitor to stabilize pulmonary capillary membrane. Without complications, the patient was extubated 2 days after operation and the following course was uneventful. Immediate institution of PEEP and pharmacological interventions to reduce pulmonary blood pressure were beneficial in arresting hemorrhage. The bleeding begins usually at the time of discontinuation of CPB. We should recognize the possible occurrence of endobronchial bleeding after pulmonary embolectomy and prepare to protect the airway and to maintain oxygenation and cardiac function.

  9. [A case of unanticipated postoperative respiratory distress from cancerous pleural effusion].

    PubMed

    Nakai, Kishiko; Kushikata, Tetsuya; Tose, Ryuji; Niwa, Hidetomo; Hirota, Kazuyoshi; Futagami, Masayuki; Yokoyama, Yoshihito

    2009-02-01

    A 63-year-old woman with a 2-month history of abdominal distension received diagnostic laparotomy under general anesthesia. The chest X-ray one week preoperatively demonstrated slight left pleural effusion, but she did not show any dyspnea on preanesthetic interview. General anesthesia was induced with propofol, ketamine and fentanyl. Sp(O2) decreased after suction of ascites, but it improved with PEEP Spontaneous respiration developped after the operation, but tidal volume was not enough and respiratory pattern was irregular. Train of four was 100%, and bronchofiberscopy had no suspicions findings. The chest X-ray and TEE revealed extended left hemilateral pleural effusion. Seven hundred seventy ml of hemorrhagic pleural fluid was suctioned. Respiratory pattern improved and the endotracheal tube was removed smoothly. We consider that we diagnosed her state only from her subjective symptoms without considering objective symptoms. Besides we had to explain a possibility of a unanticipated serious respiratory distress. In such a case, more accurate and objective diagnostic procedures are required.

  10. [Pneumothorax in multiple trauma. Radiologic and CT study].

    PubMed

    Borrè, A; Ferraris, M M; Iacono, C; Verna, V; Scala, A

    1992-10-01

    This study was aimed at evaluating the necessity to perform chest Computerized Tomography (CT) in multiple traumatized patients to diagnose pleuropulmonary lesions and, particularly, pneumothorax: the correct identification of this condition, although minimal, is important especially in prevision of long anesthesias and/or positive end-expiratory pressure (PEEP) therapy. This assisted respiratory technique improves arterial oxygenation but causes a barotrauma which may cause some complications; particularly, a small undetected pneumothorax can suddenly increase so as to cause pulmonary collapse with sometimes dramatic symptoms. Chest X-ray films and CT scans, performed in rapid succession on patient's admission in Emergency Ward, were compared in 21 subjects. CT is indispensable in case of severe chest parietal lesions which can