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

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 (PEEP5), PEEP titration targeting a minimal driving pressure (PEEP Delta P) and oesophageal pressure-guided PEEP titration (PEEPPoeso) 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 Delta P and PEEPPoeso 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 Delta P, PEEPPoeso 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 Delta P compared with PEEPPoeso (P 1/4 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 Delta P (P < 0.001 each). PEEP Delta P and PEEPPoeso improved gas-exchange, but PEEP(Poeso )resulted in lower cardiac output compared with PEEP5 and PEEP Delta P.CONCLUSION PEEP Delta P ameliorated the effects of Trendelenburg position with pneumoperitoneum during surgery on end-expiratory PTP and lung volume, decreased driving pressure and dynamic elastic power, as well as improved gas exchange while preserving cardiac output.