Electric impedance tomography and protective mechanical ventilation in elective robotic-assisted laparoscopy surgery with steep Trendelenburg position: a randomized controlled study

Electrical impedance tomography (EIT) reconstructs functional lung images and evaluates the variations of impedance during the breathing cycle. The aim of this study was to evaluate the effect of protective mechanical ventilation on ventilation distributions recorded by the EIT during elective robotic-assisted laparoscopy surgery with steep Trendelenburg position. This prospective, randomized single center study included patients with healthy lungs undergoing elective robot-assisted laparoscopic urological surgery in general anesthesia. Patients were randomly assigned to either protective lung ventilation or conventional ventilation. In the protective ventilation group, tidal volume (TV) was set at 6 ml/Kg predicted body weight (PBW), with PEEP 6 cmH(2)O, and recruitment maneuvers (RM) as needed. In the conventional ventilation group, TV was set at 9 ml/Kg PBW, with PEEP 2 cmH(2)O and RM only as needed. Ventilation distribution was assessed using an EIT device. This study included 40 patients in the functional image analysis. Significant differences were found in ventilation distribution in the region of interest (p < 0.05). Driving pressure was significantly lower in protective ventilation group (p < 0.05). Peak and plateau pressures were not different between the groups while statical significance was found in tidal volume and respiratory rate. EIT may be a valuable tool for monitoring lung function during general anesthesia. During elective robotic-assisted laparoscopy surgery with steep Trendelenburg position, protective mechanical ventilation may have a more homogenous distribution of intraoperative and postoperative ventilation. Larger sample size and long-term evaluation are needed in future studies to assess the benefit of EIT monitoring in operation room. Clinical trial registration ClinicalTrials.gov Identifier: NCT04194177 registered at 11th December 2019.