Effect of synchronized intermittent mandatory versus manual assistance ventilation during anesthetic emergence on postoperative atelectasis in patients undergoing laparoscopic abdominal surgery: a randomized controlled trial

Abstract Background Atelectasis usually leads to gas exchange and respiratory function impairment, which deteriorate the quality of recovery and increasing mortality. Although recent evidence suggested that the ventilation mode during emergence may affect the occurrence of atelectasis, the optimal ventilation mode remains controversial and randomized controlled trial is needed to clarify the issue. Methods In this prospective, randomized, and double-blind controlled trial, adult patients undergoing laparoscopic abdominal surgery at West China Hospital were assigned randomly (1:1:1) into SIMV-PC, SIMV/PSV or intermittent manual assistance ventilation group. The primary outcome was the incidence of atelectasis. The secondary outcomes included the incidence of postoperative hypoxemia, the oxygenation index and a composite of postoperative pulmonary complications (PPCs). Results Following an 8.73% dropout rate, a total of 115 patients undergoing elective laparoscopic abdominal surgery were enrolled in the final analysis. The incidence of atelectasis was lower in the pooled SIMV group compared to that in intermittent manual assistance ventilation group (29.5% vs. 48.6%, 95% CI: 0.38 to 0.98; P = 0.045). Sensitivity analyses confirmed the robustness of this result. There were no statistical differences in the secondary outcomes. Conclusions Among patients undergoing laparoscopic abdominal surgery, the use of SIMV (SIMV-PC or SIMV/PSV) during emergence resulted in a reduced incidence of early postoperative atelectasis compared to intermittent manual assistance ventilation. Future research with a larger sample size is needed. Trial registration ChiCTR2300073366. This study was registered before enrollment (July 7, 2023). Available at: https://www.chictr.org.cn/showproj.html?proj=198051 .