Effect of Ultrasound-Guided versus Conventional Lung Recruitment on End-of-Surgery Atelectasis in Adults Aged 45–74 Years Undergoing Prone-Position Spinal Surgery: A Randomized Controlled Trial

Objective: This study aimed to compare the effects of ultrasound-guided stepwise lung recruitment maneuver (LRM) versus conventional manual LRM on the incidence of end-of-surgery atelectasis in patients undergoing prone-position spinal surgery. Methods: In this randomized controlled trial, 120 patients aged 45– 74 years undergoing prone-position spine surgery under general anesthesia were randomized to ultrasound-guided group (n = 60) or conventional manual group (n = 60). Both groups received a fixed PEEP of 5 cmH 2 O intraoperatively. The primary outcome was the incidence of ultrasound-defined atelectasis at the end of surgery (T3). Results: The final analysis included 60 patients in the intervention group and 59 in the control group. The incidence of atelectasis at the end of surgery (T3) did not differ significantly between groups [73.3% (44/60) vs 71.2% (42/59); RD = 2.1%, 95% CI: − 13.9% to 18.2%; RR = 1.03, 95% CI: 0.82 to 1.29; P = 0.794]. Tidal volume at T3 was lower in the intervention group (385 ± 52 mL vs 437 ± 55 mL, P < 0.001), whereas dynamic compliance was comparable (37 ± 9 vs 36 ± 9 mL·cmH 2 O − 1 , P = 0.517). No severe postoperative pulmonary complications occurred. Exploratory analyses suggested that higher T1 PaCO 2 was associated with an increased risk of newly emerged atelectasis at T3, whereas higher T1 heart rate and higher T2 PaO 2 were associated with a reduced risk of newly emerged atelectasis at T3. In the full cohort, T2 atelectasis was associated with T3 atelectasis, but the confidence interval was wide. These findings are hypothesis-generating and require external validation. Conclusion: Under a fixed PEEP of 5 cmH 2 O, stepwise ultrasound-guided LRM did not demonstrate superiority over conventional manual LRM. Exploratory analyses suggested that T2 atelectasis and higher preoperative PaCO 2 may be associated with atelectasis at the end of surgery, requiring validation in an independent cohort. Trial Registration: Chinese Clinical Trial Registry (ChiCTR2400086097; https://www.chictr.org.cn/). Registered on June 25, 2024. Keywords: ultrasound guidance, lung recruitment, atelectasis, prone position, randomized controlled trial