The impact of inspiratory muscle training on pulmonary function recovery and pulmonary complications in patients undergoing cardiothoracic surgery: a systematic review and meta-analysis

Objective: To quantify the effects of inspiratory muscle training (IMT) on pulmonary function (PF) recovery and postoperative pulmonary complications (PPCs) including pneumonia and atelectasis in patients undergoing cardiothoracic surgery through systematic evaluation and meta-analysis, providing an evidence-based basis for perioperative respiratory management. Methods: PubMed, Embase, Cochrane Library, and Web of Science were systematically searched until May 2025, with 7 randomized controlled trials (RCTs) involving 507 adult patients who underwent cardiothoracic surgery retrieved (the study of transcatheter aortic-valve replacement was excluded due to heterogeneous surgical characteristics). The quality of the literature was evaluated using the Cochrane Risk-of-Bias Tool (RoB 2.0). A meta-analysis was conducted using RevMan 5.4 software to compare the differences in predefined outcome measures: forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and the pneumonia incidence between the IMT and control groups. Results: The meta-analysis showed that the IMT group had a higher FEV1 than the control group [mean difference (MD)=0.80 L, 95% confidence interval (CI): 0.09-1.52, P = 0.03], with clinically relevant improvements. Similarly, FVC was better in the IMT group (MD = 0.64 L, 95% CI: 0.11-1.17, P = 0.03), also representing a clinically meaningful benefit. However, there was no difference in FEV1/FVC ratio between the two groups (P = 0.15). The IMT group performed better in the 6-minute walk test (6MWT) (MD = 47.89 m, 95% CI: 1.28-94.51, P = 0.04), indicating improved functional capacity. Regarding PPCs, the incidence of postoperative pneumonia [odds ratio (OR)=0.18, 95% CI: 0.06-0.57, P = 0.004] and atelectasis (OR = 0.37, 95% CI: 0.17-0.81, P = 0.01) in the IMT group were lower than those in the control group. Conclusion: IMT can effectively improve PF and reduce the risk of PPCs in patients undergoing cardiothoracic surgery by enhancing the strength and endurance of inspiratory muscles.