Abstract
BACKGROUND: Postoperative pulmonary complications (PPCs) are common following abdominal surgery, contributing significantly to perioperative morbidity and mortality, prolonged hospitalization, and increased healthcare costs. Although various non-pharmacological strategies are frequently recommended in perioperative care, their comparative clinical effectiveness remains unclear. A rigorous synthesis of the available evidence is urgently needed to inform clinical guidelines and optimize patient outcomes. METHODS: A comprehensive literature search will be conducted in Ovid MEDLINE, Embase, and Web of Science from inception to January 2025, without language restrictions. We will include randomized controlled trials (RCTs) that evaluate structured single non-pharmacological perioperative interventions in adult patients undergoing elective abdominal surgery under general anesthesia. Only studies that clearly define PPCs will be included. The primary outcome is the proportion of patients developing composite PPCs. Secondary outcomes include each PPC subtype based on European Perioperative Clinical Outcome (EPCO) criteria (e.g., respiratory infection, respiratory failure, pleural effusion, atelectasis, or pneumothorax), hospital length of stay, and all-cause mortality. Two reviewers will independently screen studies, extract data, and assess risk of bias using the Cochrane RoB 2.0 tool. Pairwise random-effects meta-analyses using the Restricted Maximum Likelihood (REML) estimator will be performed, supplemented by trial sequential analysis to assess evidence robustness. Between-study heterogeneity will be quantified using I(2). Publication bias will be evaluated through funnel plots and Egger's test. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach will be applied to assess the quality of the published literature. DISCUSSION: This systematic review and meta-analysis aims to provide an updated and focused synthesis of non-pharmacological interventions for preventing PPCs in adult patients undergoing abdominal surgery. By incorporating recent high-quality RCTs and applying rigorous evaluation methods, the review is expected to generate evidence directly applicable to perioperative practice, enhance clinical decision-making, support guideline development, and highlight critical areas for future research. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42025637449.