Electrical Impedance Tomography vs Dynamic Compliance Guided Positive End-expiratory Pressure Titration During Laparoscopic Gynecological Surgery: A Multi-center, Prospective Randomized Trial - TITRANT

The aim of this study is to compare the effects of two different - electrical impedance tomography guided (EIT) versus dynamic pulmonary compliance guided (Cdyn) - positive end-expiratory pressure (PEEP) titrating methods on mechanical power of ventilation (MP), oxygenation, respiratory mechanics parameters, global inhomogeneity index (GI), overdistension/collapse (ODCL) and postoperative pulmonary complications (PPCs) in patients with non-injured lungs undergoing laparoscopic gynecological surgery. Despite Cdyn-directed lung protective ventilation has several proven advantages, the investigators hypothesize that optimizing intraoperative mechanical ventilation using EIT may further improve patient outcomes by reducing MP responsible for ventilator induced lung injury (VILI) and consequent PPCs. These anticipated advantages may improve the knowledge about individualized intraoperative protective ventilation, enhance postoperative recovery, shorten in-hospital stay and reduce healthcare related costs.

A total number of 200 patients scheduled for laparoscopic gynecological surgery will be enrolled in this study. An equal number of patients will be randomized into the PEEP-EIT and PEEP-Cdyn groups.

Patients randomized into the PEEP-EIT group receive a decremental PEEP titration procedure directed by EIT PEEP Trial of the Dräger PulmoVista 500 device in order to determine the individually optimal level of PEEP (PEEPopt). Patients in the PEEP-Cdyn Group will undergo the same decremental PEEP titration procedure directed by Cdyn measured by the ventilator of the anesthesia workstation.

During the PEEP titration procedure PEEP will be decreased from 18 cmH2O by 2 cmH2O every 20 ventilatory cycles, until a final PEEP of 6 cmH2O. On each level of PEEP Cdyn values will be recorded. In the PEEP-EIT Group PEEPopt is considered as the intersect between the lower percentage of overdistension and collapse, based on the diagnostic tool of the EIT device. In the PEEP-Cdyn Group optimal PEEP is considered as the PEEP value resulting the highest possible Cdyn measured by the ventilator After the titration procedure, a lung protective mechanical ventilation (LPV) will be performed using PEEPopt and low tidal volumes (TV=6 mL/kg, Ideal Body Weight) in both groups.

Mechanical Power, driving pressure, Cdyn, tidal volume in region of interest 3 and 4 (TVROI3, TVROI4) and end-expiratory lung volumes will be recorded immediately after the PEEP titration trial and every 15 minutes during surgery in both groups.