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Positive end-expiratory pressure (PEEP) level to prevent expiratory flow limitation during cardiac surgery: study protocol for a randomized clinical trial (EFLcore study).

ABSTRACT: BACKGROUND:Lung dysfunction commonly occurs after cardiopulmonary bypass (CPB). Randomized evidence suggests that the presence of expiratory flow limitation (EFL) in major abdominal surgery is associated with postoperative pulmonary complications. Appropriate lung recruitment and a correctly set positive end-expiratory pressure (PEEP) level may prevent EFL. According to the available data in the literature, an adequate ventilation strategy during cardiac surgery is not provided. The aim of this study is to assess whether a mechanical ventilation strategy based on optimal lung recruitment with a best PEEP before and after CPB and with a continuous positive airway pressure (CPAP) during CPB would reduce the incidence of respiratory complications after cardiac surgery. METHODS/DESIGN:This will be a single-center, single-blind, parallel-group, randomized controlled trial. Using a 2-by-2 factorial design, high-risk adult patients undergoing elective cardiac surgery will be randomly assigned to receive either a best PEEP (calculated with a PEEP test) or zero PEEP before and after CPB and CPAP (equal to the best PEEP) or no ventilation (patient disconnected from the circuit) during CPB. The primary endpoint will be a composite endpoint of the incidence of EFL after the weaning from CPB and postoperative pulmonary complications. DISCUSSION:This study will help to establish a correct ventilatory strategy before, after, and during CPB. The main purpose is to establish if a ventilation based on a simple and feasible respiratory test may preserve lung function in cardiac surgery. TRIAL REGISTRATION:ClinicalTrials.gov, ID: NCT02633423 . Registered on 6 December 2017.

SUBMITTER: Bignami E

PROVIDER: S-EPMC6258414 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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Positive end-expiratory pressure (PEEP) level to prevent expiratory flow limitation during cardiac surgery: study protocol for a randomized clinical trial (EFLcore study).

Bignami Elena E Spadaro Savino S Saglietti Francesco F Di Lullo Antonio A Corte Francesca Dalla FD Guarnieri Marcello M de Simone Giulio G Giambuzzi Ilaria I Zangrillo Alberto A Volta Carlo Alberto CA

Trials 20181126 1

<h4>Background</h4>Lung dysfunction commonly occurs after cardiopulmonary bypass (CPB). Randomized evidence suggests that the presence of expiratory flow limitation (EFL) in major abdominal surgery is associated with postoperative pulmonary complications. Appropriate lung recruitment and a correctly set positive end-expiratory pressure (PEEP) level may prevent EFL. According to the available data in the literature, an adequate ventilation strategy during cardiac surgery is not provided. The aim ...[more]

PMID: 30477541

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Project description:BackgroundIndividualised bedside adjustment of mechanical ventilation is a standard strategy in acute coma neurocritical care patients. This involves customising positive end-expiratory pressure (PEEP), which could improve ventilation homogeneity and arterial oxygenation. This study aimed to determine whether PEEP titrated by electrical impedance tomography (EIT) results in different lung ventilation homogeneity when compared to standard PEEP of 5 cmH2O in mechanically ventilated patients with healthy lungs.MethodsIn this prospective single-centre study, we evaluated 55 acute adult neurocritical care patients starting controlled ventilation with PEEPs close to 5 cmH2O. Next, the optimal PEEP was identified by EIT-guided decremental PEEP titration, probing PEEP levels between 9 and 2 cmH2O and finding the minimal amount of collapse and overdistension. EIT-derived parameters of ventilation homogeneity were evaluated before and after the PEEP titration and after the adjustment of PEEP to its optimal value. Non-EIT-based parameters, such as peripheral capillary Hb saturation (SpO2) and end-tidal pressure of CO2, were recorded hourly and analysed before PEEP titration and after PEEP adjustment.ResultsThe mean PEEP value before titration was 4.75 ± 0.94 cmH2O (ranging from 3 to max 8 cmH2O), 4.29 ± 1.24 cmH2O after titration and before PEEP adjustment, and 4.26 ± 1.5 cmH2O after PEEP adjustment. No statistically significant differences in ventilation homogeneity were observed due to the adjustment of PEEP found by PEEP titration. We also found non-significant changes in non-EIT-based parameters following the PEEP titration and subsequent PEEP adjustment, except for the mean arterial pressure, which dropped statistically significantly (with a mean difference of 3.2 mmHg, 95% CI 0.45 to 6.0 cmH2O, p < 0.001).ConclusionAdjusting PEEP to values derived from PEEP titration guided by EIT does not provide any significant changes in ventilation homogeneity as assessed by EIT to ventilated patients with healthy lungs, provided the change in PEEP does not exceed three cmH2O. Thus, a reduction in PEEP determined through PEEP titration that is not greater than 3 cmH2O from an initial value of 5 cmH2O is unlikely to affect ventilation homogeneity significantly, which could benefit mechanically ventilated neurocritical care patients.

Project description:BackgroundIn patients on mechanical ventilation, positive end-expiratory pressure (PEEP) can decrease cardiac output through a decrease in cardiac preload and/or an increase in right ventricular afterload. Increase in central blood volume by fluid administration or passive leg raising (PLR) may reverse these phenomena through an increase in cardiac preload and/or a reopening of closed lung microvessels. We hypothesized that a transient decrease in PEEP (PEEP-test) may be used as a test to detect volume responsiveness.MethodsMechanically ventilated patients with PEEP ≥ 10 cmH2O ("high level") and without spontaneous breathing were prospectively included. Volume responsiveness was assessed by a positive PLR-test, defined as an increase in pulse-contour-derived cardiac index (CI) during PLR ≥ 10%. The PEEP-test consisted in reducing PEEP from the high level to 5 cmH2O for one minute. Pulse-contour-derived CI (PiCCO2) was monitored during PLR and the PEEP-test.ResultsWe enrolled 64 patients among whom 31 were volume responsive. The median increase in CI during PLR was 14% (11-16%). The median PEEP at baseline was 12 (10-15) cmH2O and the PEEP-test resulted in a median decrease in PEEP of 7 (5-10) cmH2O, without difference between volume responsive and unresponsive patients. Among volume responsive patients, the PEEP-test induced a significant increase in CI of 16% (12-20%) (from 2.4 ± 0.7 to 2.9 ± 0.9 L/min/m2, p < 0.0001) in comparison with volume unresponsive patients. In volume unresponsive patients, PLR and the PEEP-test increased CI by 2% (1-5%) and 6% (3-8%), respectively. Volume responsiveness was predicted by an increase in CI > 8.6% during the PEEP-test with a sensitivity of 96.8% (95% confidence interval (95%CI): 83.3-99.9%) and a specificity of 84.9% (95%CI 68.1-94.9%). The area under the receiver operating characteristic curve of the PEEP-test for detecting volume responsiveness was 0.94 (95%CI 0.85-0.98) (p < 0.0001 vs. 0.5). Spearman's correlation coefficient between the changes in CI induced by PLR and the PEEP-test was 0.76 (95%CI 0.63-0.85, p < 0.0001).ConclusionsA CI increase > 8.6% during a PEEP-test, which consists in reducing PEEP to 5 cmH2O, reliably detects volume responsiveness in mechanically ventilated patients with a PEEP ≥ 10 cmH2O. Trial registration ClinicalTrial.gov (NCT 04,023,786). Registered July 18, 2019. Ethics Committee approval CPP Est III (N° 2018-A01599-46).

Project description:ImportanceAn intraoperative higher level of positive end-expiratory positive pressure (PEEP) with alveolar recruitment maneuvers improves respiratory function in obese patients undergoing surgery, but the effect on clinical outcomes is uncertain.ObjectiveTo determine whether a higher level of PEEP with alveolar recruitment maneuvers decreases postoperative pulmonary complications in obese patients undergoing surgery compared with a lower level of PEEP.Design, setting, and participantsRandomized clinical trial of 2013 adults with body mass indices of 35 or greater and substantial risk for postoperative pulmonary complications who were undergoing noncardiac, nonneurological surgery under general anesthesia. The trial was conducted at 77 sites in 23 countries from July 2014-February 2018; final follow-up: May 2018.InterventionsPatients were randomized to the high level of PEEP group (n = 989), consisting of a PEEP level of 12 cm H2O with alveolar recruitment maneuvers (a stepwise increase of tidal volume and eventually PEEP) or to the low level of PEEP group (n = 987), consisting of a PEEP level of 4 cm H2O. All patients received volume-controlled ventilation with a tidal volume of 7 mL/kg of predicted body weight.Main outcomes and measuresThe primary outcome was a composite of pulmonary complications within the first 5 postoperative days, including respiratory failure, acute respiratory distress syndrome, bronchospasm, new pulmonary infiltrates, pulmonary infection, aspiration pneumonitis, pleural effusion, atelectasis, cardiopulmonary edema, and pneumothorax. Among the 9 prespecified secondary outcomes, 3 were intraoperative complications, including hypoxemia (oxygen desaturation with Spo2 ≤92% for >1 minute).ResultsAmong 2013 adults who were randomized, 1976 (98.2%) completed the trial (mean age, 48.8 years; 1381 [69.9%] women; 1778 [90.1%] underwent abdominal operations). In the intention-to-treat analysis, the primary outcome occurred in 211 of 989 patients (21.3%) in the high level of PEEP group compared with 233 of 987 patients (23.6%) in the low level of PEEP group (difference, -2.3% [95% CI, -5.9% to 1.4%]; risk ratio, 0.93 [95% CI, 0.83 to 1.04]; P = .23). Among the 9 prespecified secondary outcomes, 6 were not significantly different between the high and low level of PEEP groups, and 3 were significantly different, including fewer patients with hypoxemia (5.0% in the high level of PEEP group vs 13.6% in the low level of PEEP group; difference, -8.6% [95% CI, -11.1% to 6.1%]; P < .001).Conclusions and relevanceAmong obese patients undergoing surgery under general anesthesia, an intraoperative mechanical ventilation strategy with a higher level of PEEP and alveolar recruitment maneuvers, compared with a strategy with a lower level of PEEP, did not reduce postoperative pulmonary complications.Trial registrationClinicalTrials.gov Identifier: NCT02148692.

Project description:Importance:The effects of recruitment maneuvers and positive end-expiratory pressure (PEEP) titration on clinical outcomes in patients with acute respiratory distress syndrome (ARDS) remain uncertain. Objective:To determine if lung recruitment associated with PEEP titration according to the best respiratory-system compliance decreases 28-day mortality of patients with moderate to severe ARDS compared with a conventional low-PEEP strategy. Design, Setting, and Participants:Multicenter, randomized trial conducted at 120 intensive care units (ICUs) from 9 countries from November 17, 2011, through April 25, 2017, enrolling adults with moderate to severe ARDS. Interventions:An experimental strategy with a lung recruitment maneuver and PEEP titration according to the best respiratory-system compliance (n?=?501; experimental group) or a control strategy of low PEEP (n?=?509). All patients received volume-assist control mode until weaning. Main Outcomes and Measures:The primary outcome was all-cause mortality until 28 days. Secondary outcomes were length of ICU and hospital stay; ventilator-free days through day 28; pneumothorax requiring drainage within 7 days; barotrauma within 7 days; and ICU, in-hospital, and 6-month mortality. Results:A total of 1010 patients (37.5% female; mean [SD] age, 50.9 [17.4] years) were enrolled and followed up. At 28 days, 277 of 501 patients (55.3%) in the experimental group and 251 of 509 patients (49.3%) in the control group had died (hazard ratio [HR], 1.20; 95% CI, 1.01 to 1.42; P?=?.041). Compared with the control group, the experimental group strategy increased 6-month mortality (65.3% vs 59.9%; HR, 1.18; 95% CI, 1.01 to 1.38; P?=?.04), decreased the number of mean ventilator-free days (5.3 vs 6.4; difference, -1.1; 95% CI, -2.1 to -0.1; P?=?.03), increased the risk of pneumothorax requiring drainage (3.2% vs 1.2%; difference, 2.0%; 95% CI, 0.0% to 4.0%; P?=?.03), and the risk of barotrauma (5.6% vs 1.6%; difference, 4.0%; 95% CI, 1.5% to 6.5%; P?=?.001). There were no significant differences in the length of ICU stay, length of hospital stay, ICU mortality, and in-hospital mortality. Conclusions and Relevance:In patients with moderate to severe ARDS, a strategy with lung recruitment and titrated PEEP compared with low PEEP increased 28-day all-cause mortality. These findings do not support the routine use of lung recruitment maneuver and PEEP titration in these patients. Trial Registration:clinicaltrials.gov Identifier: NCT01374022.

Project description:BackgroundPositive end-expiratory pressure (PEEP) has been demonstrated to decrease ventilator-induced lung injury in patients under mechanical ventilation (MV) for acute respiratory failure. Recently, some studies have proposed some beneficial effects of PEEP in ventilated patients without lung injury. The influence of PEEP on respiratory mechanics in children is not well known. Our aim was to determine the effects on respiratory mechanics of setting PEEP at 5 cmH2O in anesthetized healthy children.MethodsPatients younger than 15 years old without history of lung injury scheduled for elective surgery gave informed consent and were enrolled in the study. After usual care for general anesthesia, patients were placed on volume controlled MV. Two sets of respiratory mechanics studies were performed using inspiratory and expiratory breath hold, with PEEP 0 and 5 cmH2O. The maximum inspiratory and expiratory flow (QI and QE) as well as peak inspiratory pressure (PIP), plateau pressure (PPL) and total PEEP (tPEEP) were measured. Respiratory system compliance (CRS), inspiratory and expiratory resistances (RawI and RawE) and time constants (KTI and KTE) were calculated. Data were expressed as median and interquartile range (IQR). Wilcoxon sign test and Spearman's analysis were used. Significance was set at P < 0.05.ResultsWe included 30 patients, median age 39 (15-61.3) months old, 60% male. When PEEP increased, PIP increased from 12 (11,14) to 15.5 (14,18), and CRS increased from 0.9 (0.9,1.2) to 1.2 (0.9,1.4) mL·kg- 1·cmH2O- 1; additionally, when PEEP increased, driving pressure decreased from 6.8 (5.9,8.1) to 5.8 (4.7,7.1) cmH2O, and QE decreased from 13.8 (11.8,18.7) to 11.7 (9.1,13.5) L·min- 1 (all P < 0.01). There were no significant changes in resistance and QI.ConclusionsAnalysis of respiratory mechanics in anesthetized healthy children shows that PEEP at 5 cmH2O places the respiratory system in a better position in the P/V curve. A better understanding of lung mechanics may lead to changes in the traditional ventilatory approach, limiting injury associated with MV.

Dataset Information

Positive end-expiratory pressure (PEEP) level to prevent expiratory flow limitation during cardiac surgery: study protocol for a randomized clinical trial (EFLcore study).

Publications

Positive end-expiratory pressure (PEEP) level to prevent expiratory flow limitation during cardiac surgery: study protocol for a randomized clinical trial (EFLcore study).

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