Positive End-expiratory Pressure Set Research Articles

Positive End-Expiratory Pressure Setting in COVID-19-Related Acute Respiratory Distress Syndrome: Comparison Between Electrical Impedance Tomography, PEEP/FiO2 Tables, and Transpulmonary Pressure.

Introduction: The best way to titrate the positive end-expiratory pressure (PEEP) in patients suffering from acute respiratory distress syndrome is still matter of debate. Electrical impedance tomography (EIT) is a non-invasive technique that could guide PEEP setting based on an optimized ventilation homogeneity.Methods: For this study, we enrolled the patients with 2019 coronavirus disease (COVID-19)-related acute respiratory distress syndrome (ARDS), who required mechanical ventilation and were admitted to the ICU in March 2021. Patients were monitored by an esophageal catheter and a 32-electrode EIT device. Within 48 h after the start of mechanical ventilation, different levels of PEEP were applied based upon PEEP/FiO2 tables, positive end-expiratory transpulmonary (PL)/ FiO2 table, and EIT. Respiratory mechanics variables were recorded.Results: Seventeen patients were enrolled. PEEP values derived from EIT (PEEPEIT) were different from those based upon other techniques and has poor in-between agreement. The PEEPEIT was associated with lower plateau pressure, mechanical power, transpulmonary pressures, and with a higher static compliance (Crs) and homogeneity of ventilation.Conclusion: Personalized PEEP setting derived from EIT may help to achieve a more homogenous distribution of ventilation. Whether this approach may translate in outcome improvement remains to be investigated.

A Newborn with Congenital Stridor.

A Newborn with Congenital Stridor.

Electrical Impedance Tomography to Set Positive End Expiratory Pressure During Pediatric Extracorporeal Membrane Oxygenation for Respiratory Failure... Is it Feasible?

Electrical Impedance Tomography to Set Positive End Expiratory Pressure During Pediatric Extracorporeal Membrane Oxygenation for Respiratory Failure... Is it Feasible?

Individualized positive end-expiratory pressure (PEEP) during one-lung ventilation for prevention of postoperative pulmonary complications in patients undergoing thoracic surgery: A meta-analysis.

Background:Positive end-expiratory pressure (PEEP) is an important part of the lung protection strategies for one-lung ventilation (OLV). However, a fixed PEEP value is not suitable for all patients. Our objective was to determine the prevention of individualized PEEP on postoperative complications in patients undergoing one-lung ventilation.Method:We searched the PubMed, Embase, and Cochrane and performed a meta-analysis to compare the effect of individual PEEP vs fixed PEEP during single lung ventilation on postoperative pulmonary complications. Our primary outcome was the occurrence of postoperative pulmonary complications during follow-up. Secondary outcomes included the partial pressure of arterial oxygen and oxygenation index during one-lung ventilation.Result:Eight studies examining 849 patients were included in this review. The rate of postoperative pulmonary complications was reduced in the individualized PEEP group with a risk ratio of 0.52 (95% CI:0.37–0.73; P = .0001). The partial pressure of arterial oxygen during the OLV in the individualized PEEP group was higher with a mean difference 34.20 mm Hg (95% CI: 8.92–59.48; P = .0004). Similarly, the individualized PEEP group had a higher oxygenation index, MD: 49.07mmHg, (95% CI: 27.21–70.92; P < .0001).Conclusions:Individualized PEEP setting during one-lung ventilation in patients undergoing thoracic surgery was associated with fewer postoperative pulmonary complications and better perioperative oxygenation.

Personalized Positive End-Expiratory Pressure and Tidal Volume in Acute Respiratory Distress Syndrome: Bedside Physiology-Based Approach.

OBJECTIVES:Positive end-expiratory pressure and tidal volume may have a key role for the outcome of patients with acute respiratory distress syndrome. The variety of acute respiratory distress syndrome phenotypes implies personalization of those settings. To guide personalized positive end-expiratory pressure and tidal volume, physicians need to have an in-depth understanding of the physiologic effects and bedside methods to measure the extent of these effects. In the present article, a step-by-step physiologic approach to select personalized positive end-expiratory pressure and tidal volume at the bedside is described.DATA SOURCES:The present review is a critical reanalysis of the traditional and latest literature on the topic.STUDY SELECTION:Relevant clinical and physiologic studies on positive end-expiratory pressure and tidal volume setting were reviewed.DATA EXTRACTION:Reappraisal of the available physiologic and clinical data.DATA SYNTHESIS:Positive end-expiratory pressure is aimed at stabilizing alveolar recruitment, thus reducing the risk of volutrauma and atelectrauma. Bedside assessment of the potential for lung recruitment is a preliminary step to recognize patients who benefit from higher positive end-expiratory pressure level. In patients with higher potential for lung recruitment, positive end-expiratory pressure could be selected by physiology-based methods balancing recruitment and overdistension. In patients with lower potential for lung recruitment or in shock, positive end-expiratory pressure could be maintained in the 5–8 cm H2O range. Tidal volume induces alveolar recruitment and improves gas exchange. After setting personalized positive end-expiratory pressure, tidal volume could be based on lung inflation (collapsed lung size) respecting safety thresholds of static and dynamic lung stress. Positive end-expiratory pressure and tidal volume could be kept stable for some hours in order to allow early recognition of changes in the clinical course of acute respiratory distress syndrome but also frequently reassessed to avoid crossing of safety thresholds.CONCLUSIONS:The setting of personalized positive end-expiratory pressure and tidal volume based on sound physiologic bedside measures may represent an effective strategy for treating acute respiratory distress syndrome patients.

Association of early positive end-expiratory pressure settings with ventilator-free days in patients with coronavirus disease 2019 acute respiratory distress syndrome: A secondary analysis of the Practice of VENTilation in COVID-19 study.

BACKGROUNDThere is uncertainty about how much positive end-expiratory pressure (PEEP) should be used in patients with acute respiratory distress syndrome (ARDS) due to coronavirus disease 2019 (COVID-19).OBJECTIVETo investigate whether a higher PEEP strategy is superior to a lower PEEP strategy regarding the number of ventilator-free days (VFDs).DESIGNMulticentre observational study conducted from 1 March to 1 June 2020.SETTING AND PATIENTSTwenty-two ICUs in The Netherlands and 933 invasively ventilated COVID-19 ARDS patients.INTERVENTIONSPatients were categorised retrospectively as having received invasive ventilation with higher (n=259) or lower PEEP (n=674), based on the high and low PEEP/FiO2 tables of the ARDS Network, and using ventilator settings and parameters in the first hour of invasive ventilation, and every 8 h thereafter at fixed time points during the first four calendar days. We also used propensity score matching to control for observed confounding factors that might influence outcomes.MAIN OUTCOMES AND MEASURESThe primary outcome was the number of VFDs. Secondary outcomes included distant organ failures including acute kidney injury (AKI) and use of renal replacement therapy (RRT), and mortality.RESULTSIn the unmatched cohort, the higher PEEP strategy had no association with the median [IQR] number of VFDs (2.0 [0.0 to 15.0] vs. 0.0 [0.0 to 16.0] days). The median (95% confidence interval) difference was 0.21 (−3.34 to 3.78) days, P = 0.905. In the matched cohort, the higher PEEP group had an association with a lower median number of VFDs (0.0 [0.0 to 14.0] vs. 6.0 [0.0 to 17.0] days) a median difference of −4.65 (−8.92 to −0.39) days, P = 0.032. The higher PEEP strategy had associations with higher incidence of AKI (in the matched cohort) and more use of RRT (in the unmatched and matched cohorts). The higher PEEP strategy had no association with mortality.CONCLUSIONIn COVID-19 ARDS, use of higher PEEP may be associated with a lower number of VFDs, and may increase the incidence of AKI and need for RRT.TRIAL REGISTRATIONPractice of VENTilation in COVID-19 is registered at ClinicalTrials.gov, NCT04346342.

COVIDTrach: a prospective cohort study of mechanically ventilated patients with COVID-19 undergoing tracheostomy in the UK

ObjectivesCOVIDTrach is a UK multicentre prospective cohort study project that aims to evaluate the outcomes of tracheostomy in patients with COVID-19 receiving mechanical ventilation and record the incidence of SARS-CoV-2...

Clinical value of electrical impedance tomography (EIT) in the management of patients with acute respiratory failure: a single centre experience

Objective. We will describe our clinical experience using electrical impedance tomography (EIT) in the management of mechanical ventilation in patients with acute respiratory failure and to determine to which extent EIT-guided positive end-expiratory pressure (PEEP) setting differed from clinically set values. Approach. We conducted a retrospective, observational cohort study performed in a hub centre for the treatment of acute respiratory failure and veno-venous extracorporeal membrane oxygenation (ECMO). Main results. Between January 2017 and December 2019, EIT was performed 54 times in 41 patients, not feasible only in one case because of signal instability. More than 50% was on veno-venous ECMO support. In 16 cases (30%), EIT was used for monitoring mechanical ventilation, i.e. to evaluate recruitability or sigh setting. In 37 cases (70%), EIT was used to set PEEP both with incremental (11 cases in nine patients) and decremental (26 cases, 18 patients) PEEP trial. Clinical PEEP before the decremental PEEP trial (PEEPPRE) was 14.1 ± 3.4 cmH2O and clinical PEEP set by clinicians after the PEEP trial (PEEPPOST) was 13.6 ± 3.1 (p = ns). EIT analyses demonstrated that more hypoxic patients were higher derecruited when compared to less hypoxic patients that were, on the contrary, more overdistended (p < 0.05). No acute effects of PEEP adjustment based on EIT on respiratory mechanics or regional EIT parameters modification were observed. Significance. The variability of EIT findings in our population confirmed the need to provide ventilation settings individually tailored and EIT was confirmed to be an optimal useful clinical bedside noninvasive tool to provide real-time monitoring of the PEEP effect and ventilation distribution.

Early individualized positive end-expiratory pressure guided by electrical impedance tomography in acute respiratory distress syndrome: a randomized controlled clinical trial

BackgroundIndividualized positive end-expiratory pressure (PEEP) by electrical impedance tomography (EIT) has potential interest in the optimization of ventilation distribution in acute respiratory distress syndrome (ARDS). The aim of the study was to determine whether early individualized titration of PEEP with EIT improved outcomes in patients with ARDS.MethodsA total of 117 ARDS patients receiving mechanical ventilation were randomly assigned to EIT group (n = 61, PEEP adjusted based on ventilation distribution) or control group (n = 56, low PEEP/FiO2 table). The primary outcome was 28-day mortality. Secondary and exploratory outcomes were ventilator-free days, length of ICU stay, incidence of pneumothorax and barotrauma, and difference in Sequential Organ Failure Assessment (SOFA) score at day 1 (ΔD1-SOFA) and day 2 (ΔD2-SOFA) compared with baseline.Measurements and main resultsThere was no statistical difference in the value of PEEP between the EIT group and control group, but the combination of PEEP and FiO2 was different between groups. In the control group, a significantly positive correlation was found between the PEEP value and the corresponding FiO2 (r = 0.47, p < 0.00001) since a given matched table was used for PEEP settings. Diverse combinations of PEEP and FiO2 were found in the EIT group (r = 0.05, p = 0.68). There was no significant difference in mortality rate (21% vs. 27%, EIT vs. control, p = 0.63), ICU length of stay (13.0 (7.0, 25.0) vs 10.0 (7.0, 14.8), median (25th–75th percentile); p = 0.17), and ventilator-free days at day 28 (14.0 (2.0, 23.0) vs 19.0 (0.0, 24.0), p = 0.55) between the two groups. The incidence of new barotrauma was zero. Compared with control group, significantly lower ΔD1-SOFA and ΔD2-SOFA were found in the EIT group (p < 0.001) in a post hoc comparison. Moreover, the EIT group exhibited a significant decrease of SOFA at day 2 compared with baseline (paired t-test, difference by − 1 (− 3.5, 0), p = 0.001). However, the control group did show a similar decrease (difference by 1 (− 2, 2), p = 0.131).ConclusionOur study showed a 6% absolute decrease in mortality in the EIT group: a statistically non-significant, but clinically non-negligible result. This result along with the showed improvement in organ function might justify further reserach to validate the beneficial effect of individualized EIT-guided PEEP setting on clinical outcomes of patients with ARDS.Trial registration: ClinicalTrials, NCT02361398. Registered 11 February 2015—prospectively registered, https://clinicaltrials.gov/show/NCT02361398.

Effects of positive end-expiratory pressure setting of mechanical ventilation guided by esophageal pressure in the treatment of patients with traumatic craniocerebral injury combined with acute respiratory distress syndrome

Objective: To investigate the effects of positive end-expiratory pressure (PEEP) setting of mechanical ventilation guided by esophageal pressure in the treatment of patients with traumatic craniocerebral injury combined with acute respiratory distress syndrome (ARDS). Methods: The retrospective cohort study was conducted. From June 2016 to June 2018, 55 patients with traumatic craniocerebral injury combined with ARDS who met the inclusion criteria were admitted to Zhengzhou Central Hospital Affiliated to Zhengzhou University. According to PEEP setting method, 28 patients were allocated to esophageal pressure group (17 males and 11 females, aged (40±13) years) and 27 patients were allocated to PEEP-fractional concentration of inspired oxygen (FiO2) table group (18 males and 9 females, aged (38±10) years). Patients in the 2 groups were treated with mechanical ventilation guided by lung protective ventilation strategy, and the optimal PEEP at 0 (immediately), 24, 48, and 72 h after treatment was determined according to esophageal pressure and PEEP-FiO2 table, respectively. The mechanical ventilation parameters in the 2 groups were adjusted according to the optimal PEEP. The transpulmonary end-expiratory pressure, pulmonary compliance, oxygen index, central venous pressure, mean arterial pressure, and intracranial pressure at 24, 48, and 72 h after treatment were recorded. Data were statistically analyzed with analysis of variance for repeated measurement, chi-square test, independent sample t test, and Bonferroni correction. Results: The optimal PEEP of patients in esophageal pressure group at 0, 24, 48, and 72 h after treatment was (12.4±3.9), (11.2±3.5), (13.4±2.6), and (13.2±3.6) cmH2O (1 cmH2O=0.098 kPa), respectively, which was significantly higher than (8.2±2.5), (7.4±2.2), (8.3±2.3), and (8.5±2.5) cmH2O in PEEP-FiO2 table group, respectively (t=4.702, 4.743, 7.849, 5.623, P<0.01). The transpulmonary end-expiratory pressure and pulmonary compliance at 24, 48, and 72 h after treatment and oxygen index at 48 and 72 h after treatment of patients in esophageal pressure group were significantly higher than those in PEEP-FiO2 table group (t=17.852, 20.586, 19.532, 4.752, 5.256, 7.446, 2.342, 4.178, P<0.05 or P<0.01). The central venous pressure of patients in esophageal pressure group at 24, 48, and 72 h after treatment was significantly higher than that in PEEP-FiO2 table group (t=12.632, 5.247, 8.994, P<0.01), and there was no statistically significant difference in mean arterial pressure of patients between the 2 groups at 24, 48, and 72 h after treatment (P>0.05). The intracranial pressure of patients in esophageal pressure group was higher than that in PEEP-FiO2 table group at 24, 48, and 72 h after treatment, but there was no statistically significant difference between the 2 groups (P>0.05). Conclusions: For patients with traumatic craniocerebral injury combined with ARDS, the optimal PEEP can be set under the guidance of esophageal pressure method, and the mechanical ventilation parameters adjusted according to the optimal PEEP can improve lung compliance and accelerate recovery of lung function more effectively, with no adverse effect in mean arterial pressure and intracranial pressure.

Electrical Impedance Tomography for Positive End-Expiratory Pressure Setting after Bilateral Lung Transplantation

Purpose After lung transplantation (LT) the magnitude of graft recruitability is variable, therefore postoperative personalized positive end-expiratory pressure (PEEP) setting is desirable in order to minimize ventilator-induced lung injury and to reduce pulmonary complications [1]. Electrical impedance tomography (EIT) offers this opportunity by bedside estimating both alveolar collapse and overdistension throughout a decremental PEEP trial [2]. This study aims to assess the reliability of EIT-based PEEP selection compared to PEEP titration to the best respiratory system static compliance (Crs) after LT [3]. Methods All patients were deeply sedated without spontaneous breathing efforts and ventilated in volume control mode with lung-protective settings [1]. At Intensive Care Unit admission after LT, PEEP was adjusted to best Crs (PEEPCrs). Subsequently, an EIT-based decremental PEEP trial was performed through a dedicated device (Pulmovista500, Drӓger-Medical, Germany). EIT optimal PEEP (PEEPEIT) was defined as the best compromise between lung collapse and overdistension [2]. PEEPEIT was compared with PEEPCrs using Mann-Whitney test. Data are expressed as median and interquartile ranges. Results Six bilateral LT patients were enrolled (4 pulmonary fibrosis, 1 bronchiectasis and 1 bronchiolitis obliterans syndrome). Age was 57 (52-63) years and body mass index was 23.3 (20.0-25.6) kg/m2. PEEPEIT was 9 (8-13) cmH2O, not significantly different from PEEPCrs [9 (7-9) cmH2O, p = 0.413]. The loss of lung compliance due to lung collapse observed with PEEPEIT [4.8% (4.1-7.3%)] was comparable to that obtained with PEEPCrs [8.0% (6.5-12.3%) (p = 0.195)]. The loss of lung compliance consequent to lung overdistension was similar between PEEPEIT and PEEPCrs [4.0% (2.5-5.0%) vs. 1.8% (1.1-2.4%) (p = 0.134)]. Conclusion After LT, EIT is a reliable tool for individualized PEEP setting, with analogous performances to PEEP titration to the best Crs. Whether EIT is to be preferred for this purpose and the overall clinical influence of personalizing PEEP based on EIT after LT remain to be determined.

Pilot study of model-based estimation of inspiratory driving pressure in CPAP ventilation

Abstract Models of lung elastance, airway resistance, and patient work of breathing have been successfully applied to invasive mechanical ventilation data. Non-invasive mechanical ventilation data, including continuous positive airway pressure (CPAP), has presented challenges in predicting inspiratory driving pressure due to the combination of patient and device work. The model applied in this paper utilizes second order b-splines to describe inspiratory driving pressure. The model provided an accurate fit to the data, with an average root-mean-squared (RMS) error in model fit of 0.6 [0.425 – 0.675] cmH2O (median [lower quartile (LQ), upper quartile (UQ)]). Subject fit expiratory elastances were between 3.1 and 10.2 cmH2O/L and showed no correlation to set positive end-expiratory pressure (PEEP). Inspiratory driving pressure profiles approximated literature and work of breathing was shown to remain consistent between PEEP levels. Outlying data is hypothesized to be caused by subjects’ expiratory effort which was assumed negligible in the model. Further application of this model alongside validation data would provide more information on this and provide more evidence of model accuracy.

Effects of Positive End-Expiratory Pressure in “High Compliance” Severe Acute Respiratory Syndrome Coronavirus 2 Acute Respiratory Distress Syndrome*

Clinical observation suggests that early acute respiratory distress syndrome induced by the severe acute respiratory syndrome coronavirus 2 may be "atypical" due to a discrepancy between a relatively unaffected static respiratory system compliance and a significant hypoxemia. This would imply an "atypical" response to the positive end-expiratory pressure. Single-center, unblinded, crossover study. ICU of Bari Policlinico Academic Hospital (Italy), dedicated to care patients with confirmed diagnosis of novel coronavirus disease 2019. Eight patients with early severe acute respiratory syndrome coronavirus 2 acute respiratory distress syndrome and static respiratory compliance higher than or equal to 50 mL/cm H2O. We compared a "lower" and a "higher" positive end-expiratory pressure approach, respectively, according to the intervention arms of the acute respiratory distress syndrome network and the positive end-expiratory pressure setting in adults with acute respiratory distress syndrome studies. Patients were ventilated with the acute respiratory distress syndrome network and, subsequently, with the ExPress protocol. After 1 hour of ventilation, for each protocol, we recorded arterial blood gas, respiratory mechanics, alveolar recruitment, and hemodynamic variables. Comparisons were performed with analysis of variance for repeated measures or Friedman test as appropriate. Positive end-expiratory pressure was increased from 9 ± 3.5 to 17.7 ± 1.7 cm H2O (p < 0.01). Alveolar recruitment was 450 ± 111 mL. Static respiratory system compliance decreased from 58.3 ± 7.6 mL/cm H2O to 47.4 ± 14.5 mL/cm H2O (p = 0.018) and the "stress index" increased from 0.97 ± 0.03 to 1.22 ± 0.07 (p < 0.001). The PaO2/FIO2 ratio increased from 131 ± 22 to 207 ± 41 (p < 0.001), and the PaCO2 increased from 45.9 ± 12.7 to 49.8 ± 13.2 mm Hg (p < 0.001). The cardiac index went from 3.6 ± 0.4 to 2.9 ± 0.6 L/min/m (p = 0.01). Our data suggest that the "higher" positive end-expiratory pressure approach in patients with severe acute respiratory syndrome coronavirus 2 acute respiratory distress syndrome and high compliance improves oxygenation and lung aeration but may result in alveolar hyperinflation and hemodynamic alterations.

The Known Unknowns of Obesity and Extracorporeal Membrane Oxygenation.

The Known Unknowns of Obesity and Extracorporeal Membrane Oxygenation.

Individualized positive end-expiratory pressure setting in patients with severe acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation.

Patients with acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation benefit from higher positive end-expiratory pressure combined with conventional ventilation during the early extracorporeal membrane oxygenation period. The role of incremental positive end-expiratory pressure titration in patients with severe acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation remains unclear. This study aimed to determine the preferred method for setting positive end-expiratory pressure in patients with severe acute respiratory distress syndrome on veno-venous extracorporeal membrane oxygenation support. We retrospectively reviewed all subjects supported with veno-venous extracorporeal membrane oxygenation for severe acute respiratory distress syndrome from 2009 to 2019 in the intensive care units in Tianjin Third Central Hospital. Subjects were divided into two groups according to the positive end-expiratory pressure titration method used: P-V curve (quasi-static pressure-volume curve-guided positive end-expiratory pressure setting) group or Crs (respiratory system compliance-guided positive end-expiratory pressure setting) group. Forty-three subjects were included in the clinical outcome analysis: 20 in the P-V curve group and 23 in the Crs group. Initial positive end-expiratory pressure levels during veno-venous extracorporeal membrane oxygenation were similar in both groups. Incidence rates of barotrauma and hemodynamic events were significantly lower in the Crs group (all p < 0.05). Mechanical ventilation duration, intensive care unit length of stay, and hospital length of stay were significantly shorter in the Crs group than the P-V curve group (all p < 0.05). Subjects in the Crs group showed non-significant improvements in the duration of extracorporeal membrane oxygenation support and 28-day mortality (p > 0.05). Respiratory system compliance-guided positive end-expiratory pressure setting may lead to more optimal clinical outcomes for patients with severe acute respiratory distress syndrome supported by veno-venous extracorporeal membrane oxygenation. Moreover, the operation is simple, safe, and convenient in clinical practice.

Body Habitus and Dynamic Surgical Conditions Independently Impair Pulmonary Mechanics during Robotic-assisted Laparoscopic Surgery.

Body habitus, pneumoperitoneum, and Trendelenburg positioning may each independently impair lung mechanics during robotic laparoscopic surgery. This study hypothesized that increasing body mass index is associated with more mechanical strain and alveolar collapse, and these impairments are exacerbated by pneumoperitoneum and Trendelenburg positioning. This cross-sectional study measured respiratory flow, airway pressures, and esophageal pressures in 91 subjects with body mass index ranging from 18.3 to 60.6 kg/m2. Pulmonary mechanics were quantified at four stages: (1) supine and level after intubation, (2) with pneumoperitoneum, (3) in Trendelenburg docked with the surgical robot, and (4) level without pneumoperitoneum. Subjects were stratified into five body mass index categories (less than 25, 25 to 29.9, 30 to 34.9, 35 to 39.9, and 40 or higher), and respiratory mechanics were compared over surgical stages using generalized estimating equations. The optimal positive end-expiratory pressure settings needed to achieve positive end-expiratory transpulmonary pressures were calculated. At baseline, transpulmonary driving pressures increased in each body mass index category (1.9 ± 0.5 cm H2O; mean difference ± SD; P < 0.006), and subjects with a body mass index of 40 or higher had decreased mean end-expiratory transpulmonary pressures compared with those with body mass index of less than 25 (-7.5 ± 6.3 vs. -1.3 ± 3.4 cm H2O; P < 0.001). Pneumoperitoneum and Trendelenburg each further elevated transpulmonary driving pressures (2.8 ± 0.7 and 4.7 ± 1.0 cm H2O, respectively; P < 0.001) and depressed end-expiratory transpulmonary pressures (-3.4 ± 1.3 and -4.5 ± 1.5 cm H2O, respectively; P < 0.001) compared with baseline. Optimal positive end-expiratory pressure was greater than set positive end-expiratory pressure in 79% of subjects at baseline, 88% with pneumoperitoneum, 95% in Trendelenburg, and ranged from 0 to 36.6 cm H2O depending on body mass index and surgical stage. Increasing body mass index induces significant alterations in lung mechanics during robotic laparoscopic surgery, but there is a wide range in the degree of impairment. Positive end-expiratory pressure settings may need individualization based on body mass index and surgical conditions.

Effects of intra-operative positive end-expiratory pressure setting guided by oesophageal pressure measurement on oxygenation and respiratory mechanics during laparoscopic gynaecological surgery: A randomised controlled trial.

The creation of pneumoperitoneum during laparoscopic surgery can lead to adverse effects on the respiratory system. Positive end-expiratory pressure (PEEP) plays an important role in mechanical ventilation during laparoscopic surgery. To evaluate whether PEEP setting guided by oesophageal pressure (Poeso) measurement would affect oxygenation and respiratory mechanics during laparoscopic gynaecological surgery. A randomised controlled study. A single-centre trial from March 2018 to June 2018. Forty-four adult patients undergoing laparoscopic gynaecological surgery with anticipated duration of surgery more than 2 h. PEEP set according to Poeso measurement (intervention group) versus PEEP constantly set at 5 cmH2O (control group). Gas exchange and respiratory mechanics after induction and intubation (T0) and at 15 and 60 min after initiation of pneumoperitoneum (T1 and T2, respectively). PEEP during pneumoperitoneum was significantly higher in the intervention group than in the control group (T1, 12.5 ± 1.9 vs. 5.0 ± 0.0 cmH2O and T2, 12.4 ± 1.9 vs. 5.0 ± 0.0 cmH2O, both P < 0.001). Partial pressures of oxygen decreased significantly from baseline during pneumoperitoneum in the control group but not in the intervention group. Nevertheless, the changes in partial pressures of oxygen did not differ between groups. Compliance of the respiratory system (CRS) significantly decreased and driving pressure significantly increased during pneumoperitoneum in both groups. However, the changes in CRS and driving pressure were significantly less in the intervention group. Transpulmonary pressure during expiration was maintained in the intervention group while it decreased significantly in the control group. PEEP setting guided by Poeso measurement showed no beneficial effects in terms of oxygenation but respiratory mechanics were better during laparoscopic gynaecological surgery. ClinicalTrials.gov identifier: NCT03256396.

Parameter updating of a patient-specific lung mechanics model for optimising mechanical ventilation

Mechanical ventilation (MV) is the primary way to treat patients with acute respiratory distress syndrome (ARDS) in the intensive care unit (ICU). Positive-end-expiratory-pressure (PEEP) is often applied in MV to maximise gas exchange and prevent further lung damage. However, optimal MV with patient-specific PEEP level is subjective, based on clinician experience, thus increasing the risk variability, and cost of care. In this study, a single compartment lung mechanics model is employed to predict pressure outcomes at higher PEEP levels using data from lower PEEP levels. Particularly, a hysteresis loop analysis (HLA) algorithm is applied to both the dynostatic curve and pressure-volume (PV) loop to identify the lung elastance at lower PEEP levels. Pulmonary resistance can then be calculated with measured airway pressure and identified elastance. Finally, the elastance and resistance at higher PEEP levels are predicted based on model fitting techniques to obtain the pressure with changes of PEEP. The result of pressure fitting and prediction show 95% of the airway pressure curve errors are within 3% across all the 8 data sets, while peak-inspiratory-pressure (PIP) prediction errors are within 1% for all data sets. The overall approach is readily automated, thus providing an initial critical information in determining optimal MV and PEEP settings. Such a model could also be used to validate the prediction accuracy of other more complex models and improve the confidence of their clinical application. Most importantly, the ability to predict PIP and overall pressure trajectories provide a means to safely titrate PEEP to optimal levels without the necessary to build an accurate enough mathematical model which could cost plenty of time and effort.

Minor change in initial PEEP setting decreases rates of ventilator-associated events in mechanically ventilated trauma patients.

BackgroundSurveillance of ventilator-associated events (VAEs) as defined by the National Healthcare Safety Network (NHSN) is performed at many US trauma centers and considered a measure of healthcare quality. The surveillance algorithm relies in part on increases in positive end-expiratory pressure (PEEP) to identify VAEs. The purpose of this cohort study was to evaluate the effect of initiating mechanically ventilated trauma patients at marginally higher PEEP on incidence of VAEs.MethodsAnalysis of level-1 trauma center patients mechanically ventilated 2+ days from 2017 to 2018 was performed after an institutional ventilation protocol increased initial PEEP setting from 5 (2017) to 6 (2018)cm H2O. Incidence of VAEs per 1000 vent days was compared between PEEP groups. Logistic regression modelling was performed to evaluate the impact of the PEEP setting change adjusted to account for age, ventilator days, injury mechanism and injury severity.Results519 patients met study criteria (274 PEEP 5 and 245 PEEP 6). Rates of VAEs were significantly reduced among patients with initial PEEP 5 versus 6 (14.61 per 1000 vent days vs. 7.13 per 1000 vent days; p=0.039). Logistic regression demonstrated that initial PEEP 6 was associated with 62% reduction in VAEs.ConclusionsOur data suggest that an incrementally increased baseline PEEP setting was associated with a significantly decreased incidence of VAEs among trauma patients. This minor change in practice may have a major impact on a trauma center’s quality metrics.Level of evidenceIV.

Ventilator Associated Pneumonia Incidence with different Positive End-Expiratory Pressure (PEEP) settings in a Neurological ICU serving rural patients (5012)

Ventilator Associated Pneumonia Incidence with different Positive End-Expiratory Pressure (PEEP) settings in a Neurological ICU serving rural patients (5012)