Intraoperative titration of positive end-expiratory pressure in urological patients undergoing laparoscopic procedures under lateral position: a randomized controlled trial

The study aimed to investigate the role of electrical impedance tomography (EIT)-guided individualized positive end-expiratory pressure (PEEP) in surgical patients under lateral position. The urological patients undergoing elective laparoscopic surgery were randomly allocated to either the PEEPEIT (titrated with EIT) or PEEP5 (fixed PEEP = 5cmH₂O) groups. The PEEP titration protocol commenced at 3 cmH₂O, with increments of 2 cmH₂O every 2 min until reaching 17 cmH₂O. Once the EIT-titrated optimal PEEP level was determined with minimized regional overdistension and collapse, it was maintained until the end of surgery. The PaO₂/FiO₂ ratio, respiratory mechanics parameters and hemodynamic parameters were recorded at 5 min before anesthesia induction (T0), 5 min after PEEP setting (T1), at the end of surgery (T2), and 30 min after extubation (T3). A total of 46 subjects were randomized. The median PEEP was 13 cmH2O [25th − 75th percentiles, 11–14 cmH2O] in the PEEPEIT group. The PEEPEIT group had higher PaO2/FiO2 ratio (423.2 ± 42.2 vs. 349.7 ± 48.0, P<0.001) before extubation compared with the PEEP5 group. Further, PEEPEIT group had higher plateau pressure and dynamic compliance, while lower driving pressure at both T1 (all P < 0.05) and T2 (P < 0.05) time points. Hemodynamic changes were similar in two groups (P > 0.05). There was no significant statistical difference in PaO2/FiO2 ratio at 30 min after extubation between the two groups (379.7 ± 38.2 vs. 381.6 ± 54.0, P = 0.896). Employing an EIT-guided individualized PEEP level during the surgery under lateral position may improve the pulmonary ventilation and respiratory mechanics, potentially improving oxygenation. However, this improved oxygenation seems not to be maintained after extubation. China Clinical Trial Registration Center Identifier ChiCTR2100053895. Registered 02/12/2021.