Abstract
Background The intraoperative alveolar recruitment maneuver (ARM) efficiently treats atelectasis, but the effect of Fio 2 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- (Fio 2 0.4; n=44) and high-Fio 2 (Fio 2 1.0, n=46) groups. ARMs were performed 1-min post tracheal intubation and post changes between supine and Trendelenburg positions during surgery. Intraoperative Fio 2 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 Pao 2 to Fio 2 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-Fio 2 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-Fio 2 group (relative risk 1.77, 95% CI 1.27‒2.47, P <0.001). Intra- and postoperative Pao 2 to Fio 2 were similar and no postoperative pulmonary complications occurred. Atelectasis occurred more frequently when ARM was performed with high than with low Fio 2 . High-Fio 2 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 Fio 2 . No oxygenation benefit was observed in the high-Fio 2 group.
Statistical analysis plan for the Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial (ART). A randomized controlled trial
