Effects of individualised positive end-expiratory pressure titration on respiratory and haemodynamic parameters during the Trendelenburg position with pneumoperitoneum

BACKGROUND The Trendelenburg position with pneumoperitoneum during surgery promotes dorsobasal atelectasis formation, which impairs respiratory mechanics and increases lung stress and strain. Positive end-expiratory pressure (PEEP) can reduce pulmonary inhomogeneities and preserve end-expiratory lung volume (EELV), resulting in decreased inspiratory strain and improved gas-exchange. The optimal intraoperative PEEP strategy is unclear. OBJECTIVE(S) To compare the effects of individualised PEEP titration strategies on set PEEP levels and resulting transpulmonary pressures, respiratory mechanics, gas-exchange and haemodynamics during Trendelenburg position with pneumoperitoneum. DESIGN Prospective, randomised, crossover single-centre physiologic trial. SETTING University hospital. PATIENTS Thirty-six patients receiving robot-assisted laparoscopic radical prostatectomy. INTERVENTION(S) Randomised sequence of three different PEEP strategies: standard PEEP level of 5 cmH 2 O (PEEP 5 ), PEEP titration targeting a minimal driving pressure (PEEP Δ P ) and oesophageal pressure-guided PEEP titration (PEEP Poeso ) targeting an end-expiratory transpulmonary pressure ( P TP ) of 0 cmH 2 O. MAIN OUTCOME MEASURES The primary endpoint was the PEEP level when set according to PEEP Δ P and PEEP Poeso compared with PEEP of 5 cmH 2 O. Secondary endpoints were respiratory mechanics, lung volumes, gas-exchange and haemodynamic parameters. RESULTS PEEP levels differed between PEEP Δ P , PEEP Poeso and PEEP5 (18.0 [16.0 to 18.0] vs. 20.0 [18.0 to 24.0]vs. 5.0 [5.0 to 5.0] cmH 2 O; P < 0.001 each). End-expiratory P TP and lung volume were lower in PEEP Δ P compared with PEEP Poeso ( P = 0.014 and P < 0.001, respectively), but driving pressure, lung stress, as well as respiratory system and dynamic elastic power were minimised using PEEP Δ P ( P < 0.001 each). PEEP Δ P and PEEP Poeso improved gas-exchange, but PEEP Poeso resulted in lower cardiac output compared with PEEP 5 and PEEP Δ P . CONCLUSION PEEP Δ P ameliorated the effects of Trendelenburg position with pneumoperitoneum during surgery on end-expiratory P TP and lung volume, decreased driving pressure and dynamic elastic power, as well as improved gas-exchange while preserving cardiac output. TRIAL REGISTRATION German Clinical Trials Register (DRKS00028559, date of registration 2022/04/27). https://drks.de/search/en/trial/DRKS00028559