Effect of EIT-guided individualized PEEP setting on the incidence of hypoxemia in elderly patients undergoing robot-assisted radical prostatectomy

Abstract

Objective: To investigate the effect of individualized positive end expiratory pressure (PEEP) setting guided by chest electrical impedance tomography (EIT) on the incidence of hypoxemia in elderly patients undergoing robot-assisted radical prostatectomy in the post anesthesia care unit (PACU). Methods: From September 2020 to October 2021, sixty elderly patients, with the American Association of Anesthesiologists (ASA) of Grade Ⅰ to Ⅲ, who underwent selective robot-assisted radical prostatectomy under general anesthesia in the Cancer Hospital Affiliated to Fudan University were selected. The participants were divided into two groups by the minimum randomized grouping method: EIT-PEEP group (EP group, n=30) and fixed PEEP group (FP group, n=30). After completion of tracheal intubation and establishment of pneumoperitoneum flexion posture, the individualized PEEP setting was guided by EIT in EP group, and the PEEP setting in FP group was 5 cmH2O (1 cmH2O=0.098 kPa) to the end of operation. During the operation, the ventilation mode of pressure regulation volume control was adopted. The driving pressure, dynamic lung compliance (Cdyn), oxygenation index and hemodynamics were recorded at 5 min (T1), 30 min (T2), 60 min (T3) after PEEP setting and at the time of tracheal catheter removal (T4) in both groups. The primary end point was the incidence of hypoxemia in PACU after extubation. Results: The incidence of hypoxemia after extubation was 3.3% (1/30) in EP group and 26.7% (8/30) in FP group (P=0.030). The difference of driving pressure between the two groups at T2 [(13.1±2.4) cmH2O vs (14.9±2.9) cmH2O, P=0.012], T3 [(12.7±2.4) cmH2O vs (15.6±2.8) cmH2O, P<0.001] was statistically significant. In EP group, Cdyn was improved at T2 [(38.4±7.2) ml/cmH2O vs (31.9±5.2) ml/cmH2O, P=0.006] and T3 [(37.5±9.0) ml/cmH2O vs (30.4±5.9) ml/cmH2O, P=0.001]. In EP group, PaO2/FiO2 increased at T1 [(465.7±84.5) mmHg vs (383.5±58.0) mmHg, 1 mmHg=0.133 kPa, P<0.001], T2 [(504.7±105.8) mmHg vs (418.9±73.7) mmHg, P=0.001], T3 [(520.7±92.2) mmHg vs (423.2±90.7) mmHg, P<0.001], T4 [(368.7±42.0) mmHg vs (339.5±54.9) mmHg, P=0.024]. Conclusion: The individualized PEEP setting guided by EIT can reduce the incidence of hypoxemia in elderly patients undergoing robot assisted radical prostatectomy in PACU.