Does Dynamic Compliance-Guided PEEP Titration Reduce Postoperative Pulmonary Aeration Loss in Laparoscopic Bariatric Surgery? Randomized Controlled Trial

Background and Objectives: Patients with obesity undergoing laparoscopic bariatric surgery face elevated perioperative pulmonary risk due to impaired respiratory mechanics, reduced functional residual capacity, and pneumoperitoneum-induced atelectasis. Intraoperative changes in intra-abdominal pressure and surgical positioning substantially alter respiratory mechanics, yet studies evaluating repeated PEEP titration at multiple intraoperative time points remain limited. This study aimed to determine whether dynamic compliance-guided individualized PEEP titration, applied at three distinct intraoperative stages, reduces postoperative pulmonary aeration loss compared to fixed 8 cmH2O PEEP. Methods: In this single-center randomized controlled trial with blinded outcome assessment, 70 patients with obesity (BMI ≥ 35 kg/m2) undergoing laparoscopic bariatric surgery were randomized 1:1 to the CDYN group (dynamic compliance-guided PEEP titration at T1: post-induction, T2: during pneumoperitoneum, T3: post-deflation; n = 35) or the PEEP8 group (fixed PEEP 8 cmH2O; n = 35). The primary outcome was the modified lung ultrasound score (mLUSS), assessed 30 min after PACU arrival by a blinded investigator (ClinicalTrials.gov: NCT06994780). Results: Total mLUSS was significantly lower in the CDYN group (2.20 ± 1.16 vs. 5.80 ± 2.14; p < 0.001), with significant differences in both hemithoraces. The PaO2/FiO2 ratio at PACU was significantly higher in the CDYN group (425.11 ± 127.13 vs. 311.65 ± 92.59 mmHg; p < 0.001), and the supplemental oxygen requirement was significantly lower (p = 0.001). Dynamic compliance was consistently higher throughout surgery (all p < 0.001) without differences in airway pressures or hemodynamics. Conclusions: Dynamic compliance-guided individualized PEEP titration, applied at three intraoperative stages, significantly reduces early postoperative pulmonary aeration loss and improves oxygenation in patients with obesity undergoing laparoscopic bariatric surgery, without increasing barotrauma risk or hemodynamic instability.