Driving pressure guided ventilation versus conventional lung protective strategy in morbid obese patients undergoing laparoscopic bariatric surgery: a prospective randomized controlled study

Postoperative pulmonary complications are common and associated with significant morbidity and mortality; however, the optimal intra-operative ventilation strategy to prevent postoperative pulmonary complications remains unclear. The aim of this study was to evaluate the effect of intra-operative ventilation strategy, including tidal volumes, positive end-expiratory pressure (PEEP) and use of recruitment manoeuvres on the incidence of postoperative pulmonary complications in adults having non-cardiothoracic surgery. Relevant databases were searched to identify randomised controlled trials that directly compared intra-operative ventilation strategies among surgical patients who were followed up for > 24 hours postoperatively and reported at least one outcome of interest. A total of 51 randomised controlled trials were included. Compared with a high tidal volume/zero PEEP strategy, low tidal volume strategies likely reduced the risk of postoperative pulmonary complications when combined with: high PEEP (risk ratio (RR) 0.44, 95%CI 0.22-0.87); high PEEP with recruitment manoeuvres (RR 0.60, 95%CI 0.49-0.75); personalised PEEP with recruitment manoeuvres (RR 0.53, 95%CI 0.42-0.69); low PEEP (RR 0.63, 95%CI 0.50-0.78); and low PEEP with recruitment manoeuvres (RR 0.65, 95%CI 0.46-0.93) (all moderate certainty evidence). Compared with a low tidal volume/low PEEP strategy, a low tidal volume strategy with personalised PEEP likely reduces the risk of postoperative pulmonary complications (RR 0.85, 95%CI 0.73-0.99, moderate certainty). Among patients undergoing non-cardiothoracic surgery, the use of intra-operative low tidal volume ventilation with a range of acceptable PEEP levels likely reduced the risk of postoperative pulmonary complications compared with high tidal volumes and zero PEEP. This study highlights the need for implementation research at both the provider and system levels to improve intra-operative adherence to lung protective ventilation strategies.

Positive end-expiratory pressure in obese patients during general anaesthesia. The role of intra-abdominal pressure

Intraoperative Positive End-expiratory Pressure for Obese Patients: A Step Forward, a Long Road Still Ahead.

BackgroundObesity is a global epidemic, and it is widely known that increased Body mass index (BMI) is associated with alterations in respiratory mechanics. Bariatric surgery is established as an effective treatment for this condition.ObjectiveTo assess the safety and effectiveness of different ventilation strategies in obese patients undergoing bariatric surgery.MethodsA systematic review of randomized clinical trials aimed at evaluating ventilation strategies for obese patients was carried out. Primary outcomes: in-hospital mortality, adequacy of gas exchange, and respiration mechanics alterations.ResultsFourteen clinical trials with 574 participants were included. When recruitment maneuvers (RM) vs Positive end-expiratory pressure (PEEP) were compared, RM resulted in better oxygenation p = 0.03 (MD 79.93), higher plateau pressure p < 0.00001 (MD 7.30), higher mean airway pressure p < 0.00001 (MD 6.61), and higher compliance p < 0.00001 (MD 21.00); when comparing RM + Zero end-expiratory pressure (ZEEP) vs RM + PEEP 5 or 10 cmH2O, RM associated with PEEP led to better oxygenation p = 0.001 (MD 167.00); when comparing Continuous Positive Airway Pressure (CPAP) 40 cmH2O + PEEP 10 cmH2O vs CPAP 40 cmH2O + PEEP 15 cmH2O, CPAP 40 + PEEP 15 achieved better gas exchange p = 0.003 (MD 36.00) and compliance p = 0.0003 (MD 3.00).ConclusionThere is some evidence that the alveolar recruitment maneuvers associated with PEEP lead to better oxygenation and higher compliance. There is no evidence of differences between pressure control ventilation (PCV) and Volume control ventilation (VCV).

Randomized Trial of Protective Lung Ventilation in Organ Donors

Background:Laparoscopic bariatric surgeries in morbid obese patients may be associated with atelectasis, hypercapnia, and hypoxemia, intra and postoperatively. Several strategies are used for the prevention of these consequences. This study aimed to examine the effects of three different recruitment maneuvers comparatively during surgery and the influence of the maneuvers on some cardiopulmonary indices.Materials and Methods:In a clinical trial, ninety participants of laparoscopic surgery with body mass index higher than 40 were randomly divided into three equal groups. The first group was subject to 10 cmH2O positive end-expiratory pressure (PEEP) during surgery, the second group, after venting the pneumoperitoneum, had 5 deep breaths with a positive pressure of 40 cmH2O, and the third group was subject to both. Some pulmonary and hemodynamic parameters were measured every 15 min and compared between three groups.Results:The average of peak airway pressure, plateau airway pressure, and SpO2 static and dynamic compliance between the three groups had no meaningful differences (P > 0.05), but PaCO2in the second group was statistically higher than the other two groups (P < 0.05).Conclusion:Multiple deep breaths alone are not as effective as PEEP or PEEP plus MDB in preventing adverse pulmonary effects in laparoscopic bariatric surgeries of morbid obese patients.

The effect of driving pressure-guided versus conventional mechanical ventilation strategy on pulmonary complications following on-pump cardiac surgery: A randomized clinical trial

Supraglottic airway versus tracheal intubation and the risk of postoperative pulmonary complications

Individualized positive end-expiratory pressure with and without recruitment maneuvers in obese patients during bariatric surgery.

The purpose of this study was to assess the changes in regional cerebral oxygen saturation (rScO2) in response to different ventilation strategies: inspired oxygen concentration (FiO2), end-tidal carbon dioxide (EtCO2), and positive end expiratory pressure (PEEP) in addition to optimizing mean arterial pressure (MAP) in obese patients subjected to laparoscopic bariatric surgery in the reverse trendelenburg position. 50 obese patients were randomly assigned into one of two groups. Each group is 25 patients. Control patients subjected to a ventilation strategy aimed to maintain FiO2 0.4 and EtCO2 30mmHg without PEEP. Study patients were assigned to specific protocol; T0, baseline rScO2; T1, 5min following induction; T2, PP/RTP (10min after pneumoperitoneum and reverse trendelenburg position); T3, PEEP 10cmH2O; T4, FiO2 1.0; T5, EtCO2 40mmHg and T6, MAP/BL; MAP back to baseline in both groups. 10min after PP/RTP, there was a significant decrease in rScO2 in both groups. At T4, with FiO2 1.0, there was significant improvement in rScO2 when compared to T2. At T5, with EtCO2 40mmHg, rScO2 significantly enhanced when compared to EtCO2 30mmHg. At T4 and T5, we observed highly significance difference between both groups. At the end of the procedure and when MAP increased back to baseline (T6) in both groups, rScO2 statistically increased in both groups when compared to T2. In obese patients, subjected to laparoscopic bariatric surgery in reverse trendelenburg position, adjustment of ventilation strategies and hemodynamic optimization succeeded to improve rScO2.

The effect of individualized high positive end-expiratory pressure (PEEP) and recruitment maneuvers, targeting a low driving pressure, on clinical outcomes in patients undergoing open abdominal surgery is uncertain. To compare driving pressure-guided high PEEP and recruitment maneuvers with standard low PEEP without recruitment maneuvers with respect to postoperative pulmonary complications. Randomized clinical trial of 1435 adults at increased risk for postoperative pulmonary complications who were scheduled for open abdominal surgery. The trial was conducted at 29 sites in 5 countries across Europe from April 2019 to December 2024; final follow-up was in March 2025. Statistical analysis was conducted in May 2025. Patients were randomized to undergo intraoperative ventilation with driving pressure-guided high PEEP and recruitment maneuvers (n = 718) or to intraoperative ventilation with standard low PEEP (n = 717). All patients received low tidal volume ventilation. The primary outcome was a composite of pulmonary complications within the first 5 postoperative days, including severe respiratory failure, bronchospasm, suspected pulmonary infection, pulmonary infiltrates, aspiration pneumonitis, atelectasis, acute respiratory distress syndrome, pleural effusion, cardiopulmonary edema, and pneumothorax. Among the 16 prespecified secondary outcomes, 4 concerned intraoperative complications, including hypotension (decrease in mean arterial pressure of >20% for >3 minutes) and desaturation (Spo2 <92% for >1 minute). Among 1468 adults, 1435 (98%) completed the trial (median [IQR] age, 66 [57-74] years; 52% female). In the primary analysis population, the primary outcome occurred in 142 of 718 patients (19.8%) in the driving pressure-guided high PEEP group compared with 125 of 717 patients (17.4%) in the low PEEP group (absolute difference, 2.5% [95% CI, -1.5% to 6.4%]; P = .23). The incidence of hypotension (382 [54.0%] vs 317 [45.0%]) and use of vasoactive agents (224 [32.0%] vs 130 [18.8%]) was higher in the high PEEP group; the incidence of intraoperative desaturation (6 [0.8%] vs 20 [2.8%]) was higher in the low PEEP group. Among patients at increased risk for postoperative pulmonary complications undergoing open abdominal surgery under general anesthesia, intraoperative ventilation with driving pressure-guided high PEEP and recruitment maneuvers, compared with a strategy with standard low PEEP, did not reduce postoperative pulmonary complications. ClinicalTrials.gov Identifier: NCT03884543.

BackgroundVentilator-induced lung injury caused by mechanical ventilation under general anesthesia as well as CO2 pneumoperitoneum and special positions for laparoscopy may increase the risk of postoperative pulmonary complications (PPCs). Lung protective ventilation under general anesthesia is advised by the guidelines to lower the risk of PPCs in surgical patients. However, there is considerable controversy about the optimal level of positive end-expiratory pressure (PEEP) and how to set it. Driving pressure reflects the overall respiratory stress and high driving pressure is an independent risk factor for PPCs. The purpose of this study is to explore whether driving pressure-guided individualized PEEP ventilation can lower the incidence of postoperative atelectasis by improving respiratory mechanics during laparoscopic surgery consequently lowering the incidence of PPCs compared with the traditional fixed PEEP ventilation strategy.MethodsThe study will be a single-center, prospective, randomized controlled clinical study. A total of 106 adult patients with medium-to-high-risk PPCs undergoing laparoscopic surgery for more than 2 h will be randomly assigned in a 1:1 ratio to receive an individualized PEEP guided by minimum driving pressure (group D) or a fixed PEEP of 5 cmH2O (group C). Patients in group C will maintain a PEEP of 5 cmH2O throughout the whole process, and patients in group D will be administered individualized PEEP after the start of pneumoperitoneum to achieve minimum driving pressure until the end of the operation. The primary outcome is the LUS score at 24 h postoperatively. The secondary outcomes are the LUS scores at other time points, intraoperative respiratory mechanics and oxygenation index, incidence and specific types of PPCs at 7 days postoperatively.DiscussionThis study will better evaluate the effect of individualized PEEP application guided by driving pressure on the incidence of postoperative atelectasis based on ultrasound assessment consequently the incidence of PPCs in patients undergoing prolonged laparoscopic surgery. The results may provide a clinical evidence for optimizing perioperative lung protection strategies.Trial registrationwww.chictr.org.cn ChiCTR2300079041. Registered on December 25, 2023.

In obese patients (OP), the best intraoperative ventilation strategy remains to be defined. Dynamic lung compliance (Cdyn) and dead space fraction are indicators of efficient ventilation at an optimal positive end-expiratory pressure (PEEP). Herein, we investigated whether intraoperative dynamic lung compliance optimization through PEEP manipulations affects the incidence of postoperative hypoxemia (SpO2 < 90%) in OP undergoing laparoscopic bariatric surgery (LBS). This was a single-center, prospective, randomized controlled study conducted from July 2013 to December 2015. After obtaining institutional review board approval and informed consent, 100 OP undergoing LBS under volume-controlled ventilation (tidal volume 8mL/kg of ideal body weight) were randomized according to the PEEP level maintained during the surgery. In the control group, a PEEP of 10cm H2O was maintained, while in the intervention group, the PEEP was adapted to achieve the best dynamic lung compliance. Anesthesia and analgesia were standardized. The patients received supplemental nasal oxygen on the first postoperative day and were monitored up to the second postoperative day with a portable pulse oximeter. Demographics were similar between groups. There was no difference in the incidence of hypoxemia during the first 2 postoperative days (control: 1.3%; intervention: 2.1%; p = 0.264). The incidence of postoperative hypoxemia was not reduced by an open-lung approach with protective ventilation strategy in obese patients undergoing LBS. A pragmatic application of a PEEP level of 10cm H2O was comparable to individual PEEP titration in these patients. Clinicaltrials.gov identifier, NCT02579798; https://clinicaltrials.gov/ct2/show/NCT02579798.

BackgroundThis study compares the effect of positive end-expiratory pressure (PEEP) on postoperative pulmonary complications (PPCs) in patients with obesity undergoing laparoscopic bariatric surgery (LBS) under general anesthesia with mechanical ventilation.MethodsA comprehensive search was conducted in PubMed, Embase, Web of Science, Cochrane Central Register of Controlled Trials, China National Knowledge Internet, Wanfang database, and Google Scholar for studies published up to July 29, 2023, without time or language restrictions. The search terms included “PEEP,” “laparoscopic,” and “bariatric surgery.” Randomized controlled trials comparing different levels of PEEP or PEEP with zero-PEEP (ZEEP) in patients with obesity undergoing LBS were included. The primary outcome was a composite of PPCs, and the secondary outcomes were intraoperative oxygenation, respiratory compliance, and mean arterial pressure (MAP). A fixed-effect or random-effect model was selected for meta-analysis based on the heterogeneity of the included studies.ResultsThirteen randomized controlled trials with a total of 708 participants were included for analysis. No statistically significant difference in PPCs was found between the PEEP and ZEEP groups (risk ratio = 0.27, 95% CI: 0.05–1.60; p = 0.15). However, high PEEP ≥ 10 cm H2O significantly decreased PPCs compared with low PEEP < 10 cm H2O (risk ratio = 0.20, 95% CI: 0.05–0.89; p = 0.03). The included studies showed no significant heterogeneity (I2 = 20% & 0%). Compared with ZEEP, PEEP significantly increased intraoperative oxygenation and respiratory compliance (WMD = 74.97 mm Hg, 95% CI: 41.74-108.21; p < 0.001 & WMD = 9.40 ml cm H2O− 1, 95% CI: 0.65–18.16; p = 0.04). High PEEP significantly improved intraoperative oxygenation and respiratory compliance during pneumoperitoneum compared with low PEEP (WMD = 66.81 mm Hg, 95% CI: 25.85-107.78; p = 0.001 & WMD = 8.03 ml cm H2O− 1, 95% CI: 4.70-11.36; p < 0.001). Importantly, PEEP did not impair hemodynamic status in LBS.ConclusionsIn patients with obesity undergoing LBS, high PEEP ≥ 10 cm H2O could decrease PPCs compared with low PEEP < 10 cm H2O, while there was a similar incidence of PPCs between PEEP (8–10 cm H2O) and the ZEEP group. The application of PEEP in ventilation strategies increased intraoperative oxygenation and respiratory compliance without affecting intraoperative MAP. A PEEP of at least 10 cm H2O is recommended to reduce PPCs in patients with obesity undergoing LBS.Registration numberCRD42023391178 in PROSPERO.

BackgroundIntraoperative driving pressure (ΔP) is associated with development of postoperative pulmonary complications (PPC). When tidal volume (VT) is kept constant, ΔP may change according to positive end-expiratory pressure (PEEP)-induced changes in lung aeration. ΔP may decrease if PEEP leads to a recruitment of collapsed lung tissue but will increase if PEEP mainly causes pulmonary overdistension. This study tests the hypothesis that individualized high PEEP, when compared to fixed low PEEP, protects against PPC in patients undergoing open abdominal surgery.MethodsThe “Driving prESsure durIng GeNeral AnesThesIa for Open abdomiNal surgery trial” (DESIGNATION) is an international, multicenter, two-group, double-blind randomized clinical superiority trial. A total of 1468 patients will be randomly assigned to one of the two intraoperative ventilation strategies. Investigators screen patients aged ≥ 18 years and with a body mass index ≤ 40 kg/m2, scheduled for open abdominal surgery and at risk for PPC. Patients either receive an intraoperative ventilation strategy with individualized high PEEP with recruitment maneuvers (RM) (“individualized high PEEP”) or one in which PEEP of 5 cm H2O without RM is used (“low PEEP”). In the “individualized high PEEP” group, PEEP is set at the level at which ΔP is lowest. In both groups of the trial, VT is kept at 8 mL/kg predicted body weight. The primary endpoint is the occurrence of PPC, recorded as a collapsed composite of adverse pulmonary events.DiscussionDESIGNATION will be the first randomized clinical trial that is adequately powered to compare the effects of individualized high PEEP with RM versus fixed low PEEP without RM on the occurrence of PPC after open abdominal surgery. The results of DESIGNATION will support anesthesiologists in their decisions regarding PEEP settings during open abdominal surgery.Trial registrationClinicaltrials.gov, NCT03884543. Registered on 21 March 2019.