Effects of low inspired oxygen fraction during alveolar recruitment maneuver on postoperative pulmonary complications in patients undergoing thoracoscopic lung surgery: A randomized controlled trial

Background: Patients undergoing lung surgery face an increased risk of postoperative atelectasis and pulmonary complications, primarily due to one-lung ventilation, low tidal volume, and high fraction of inspired oxygen (FiO 2 ). The alveolar recruitment maneuver (ARM) effectively reduces atelectasis; however, using pure oxygen during this procedure may attenuate its beneficial effects. Moreover, the effects of this procedure fade over time. Therefore, we assessed the efficacy of the ARM with a low FiO 2 (0.4) in preventing atelectasis and associated postoperative pulmonary complications (PPCs). Methods: Overall, the included 120 patients scheduled for thoracoscopic lung surgery randomly divided into two groups. All patients received similar anesthesia management and mechanical ventilation during surgery. Before extubation, the ARM with a continuous positive airway pressure of 20 cmH 2 O for 15–20s was administered with an FiO 2 of 1.0 in group C and an FiO 2 of 0.4 in group L. The primary outcome was the incidence of atelectasis and other pulmonary complications within 7 days after surgery. Atelectasis was assessed using postoperative chest radiography or computed tomography findings and lung ultrasound scores (LUSs). Results: The incidence of PPCs within 7 days of surgery was not significantly different between the two groups. Eighteen patients in group C had pulmonary complications within 7 days after surgery, and 11 had respiratory failure. In group L, 13 patients had pulmonary complications within 7 days after surgery, and four had respiratory failure. There were no significant differences in the LUSs before anesthesia between the two groups. However, the LUSs were significantly lower in group L than in group C 1 h after extubation. Conclusions: The incidence of pulmonary complications in both groups within 7 days after surgery was similar. However, the incidence of postoperative respiratory failure was less, and atelectasis in the early postoperative period was reduced when the ARM was conducted with an FiO 2 of 0.4. Trial registration This trial was registered in the Chinese Clinical Trial Registry (www.chictr.org.cn). first registration in 27/04/2022 and registration number ChiCTR2200059216.