Non-drug perioperative interventions to reduce postoperative pulmonary complications after abdominal surgery: systematic review and meta-analysis.

OBJECTIVE: To evaluate the effectiveness of perioperative non-drug interventions in reducing postoperative pulmonary complications (PPCs) in adults undergoing abdominal surgery. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Ovid MEDLINE, Embase, and Web of Science from database inception to January 2025 and updated in January 2026, with no language restrictions. STUDY SELECTION: Randomised controlled trials assessing the effectiveness of perioperative non-drug interventions for the prevention of PPCs in adults undergoing elective abdominal surgery under general anaesthesia, with clearly defined PPCs. MAIN OUTCOME MEASURES: The primary outcome was the proportion of patients developing PPCs. Secondary outcomes included the proportion of patients with PPC subtypes according to European Perioperative Clinical Outcome definitions (respiratory infection, respiratory failure, pleural effusion, atelectasis, or pneumothorax) and hospital length of stay. DATA EXTRACTION AND SYNTHESIS: Two reviewers independently screened studies, extracted data, and assessed risk of bias with the Cochrane RoB 2.0 tool. Data were synthesised using meta-analyses and trial sequential analyses, with the evidence certainty assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. RESULTS: 255 trials including 55 260 participants were included, evaluating 10 types of interventions with 39 subtypes for PPC prevention. PPCs occurred in 6467 (11.7%) participants across all included trials. High certainty evidence showed that low fraction of inspired oxygen (FiO CONCLUSIONS: This synthesis establishes an evidence hierarchy for PPC prevention in abdominal surgery. Low FiO STUDY REGISTRATION: PROSPERO CRD42025637449.