The effect of the fraction of inspired oxygen during alveolar recruitment on absorption atelectasis in laparoscopic surgery: A randomized, controlled trial

Abstract

Background The intraoperative alveolar recruitment maneuver (ARM) efficiently treats atelectasis, but the effect of Fio2 during ARM on atelectasis is uncertain. Here, we investigated this effect. Methods Patients undergoing elective laparoscopic surgery in the Trendelenburg position were randomized to low- (Fio2 0.4; n = 44) and high-Fio2 (Fio2 1.0, n = 46) groups. ARMs were performed 1-min post tracheal intubation and post changes between supine and Trendelenburg positions during surgery. Intraoperative Fio2 was set at 0.4 for both groups. Modified lung ultrasound (LUS) scores were calculated to assess lung aeration after inducing anesthesia and at surgery completion. The primary outcome was modified LUS score at the end of the surgery, and secondary outcomes were the intra- and postoperative Pao2 to Fio2 ratio and postoperative pulmonary complications. Results Both groups presented similar modified LUS scores before capnoperitoneum and ARM (P = 0.747). However, the postoperative modified LUS score was significantly lower in the low- than in the high-Fio2 group (7.0 ± 4.1 vs 11.7 ± 4.2, mean difference 4.7, 95% CI 2.96–6.44, P < 0.001). Significant atelectasis postoperatively was more common in the high-Fio2 group (relative risk 1.77, 95% CI 1.27‒2.47, P < 0.001). Intra- and postoperative Pao2 to Fio2 were similar and no postoperative pulmonary complications occurred. Atelectasis occurred more frequently when ARM was performed with high than with low Fio2. High-Fio2 did not benefit oxygenation. Conclusions In patients undergoing laparoscopic surgery in the Trendelenburg position, absorption atelectasis occurred more frequently when the ARM was performed with high rather than low Fio2. No oxygenation benefit was observed in the high-Fio2 group. Trial registration: ClinicalTrials.gov, NCT03943433. Registered 7 May 2019, https://clinicaltrials.gov/ct2/show/NCT03943433