The effect of ultrasound-guided lung recruitment maneuvers on postoperative atelectasis: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND

Postoperative atelectasis is common after general anesthesia. Lung ultrasound may help individualize recruitment maneuvers, but the certainty and generalizability of the evidence remain uncertain.

METHODS

We searched PubMed, Embase, Scopus, and the Cochrane Library through March 25, 2026 for randomized controlled trials (RCTs) of intraoperative ultrasound-guided lung recruitment maneuvers in adults undergoing elective surgery. The primary outcome was postoperative atelectasis assessed by lung ultrasound. Secondary outcomes were postoperative pulmonary complications (PPCs) and length of hospital stay. A random-effects model was used to calculate pooled risk ratios (RR) and mean differences (MD) with 95% confidence intervals (CIs). The certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

Ten RCTs involving 1,076 patients were included. Ultrasound-guided lung recruitment maneuvers were associated with a lower incidence of postoperative atelectasis (RR, 0.64, 95% CI, 0.52 to 0.77, P < 0.0001, I2 = 50.8%). The effect appeared clearer in abdominal surgery than in thoracic surgery. PPCs were not significantly reduced in the primary analysis (RR, 0.70, 95% CI, 0.48 to 1.01, P = 0.0571, I2 = 59.2%), and length of hospital stay was statistically but modestly shorter (MD -0.56 days, 95% CI -0.94 to -0.18, P = 0.0039, I2 = 67.7%).

CONCLUSION

Ultrasound-guided lung recruitment maneuvers may reduce postoperative atelectasis, especially in abdominal surgery, but the certainty of evidence is limited by the small evidence base, residual clinical and statistical heterogeneity, operator dependency of lung ultrasound, and inconsistent outcome definitions. The modest reduction in hospital stay should be interpreted cautiously. Larger standardized trials are needed before broad clinical implementation can be recommended.