Effect of Inspiratory Muscle Training on Outcomes After Cardiac Surgery: A Comprehensive Meta-Analysis of Randomized Controlled Trials.

Purpose: Inspiratory muscle training (IMT) has emerged as a potential intervention to improve respiratory outcomes for patients undergoing cardiac surgery. However, the extent of the IMT effects on preoperative and postoperative respiratory metrics remains uncertain. Hence, we designed this study to determine the effects of IMT on various outcomes of patients undergoing cardiac surgery.

Methods: We conducted a comprehensive meta-analysis of studies evaluating the impact of preoperative and postoperative IMT on various respiratory variables and postsurgical outcomes. We synthesized data from multiple studies, encompassing diverse patient populations and IMT protocols. The key outcomes included the maximal inspiratory pressure (MIP), forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), and others.

Results: Our meta-analysis results showed that preoperative IMT significantly improved the MIP values with a pooled standard mean difference (SMD) of 0.62. The hospital stay length was also reduced with a SMD of - 0.4. Other variables such as FEV1 and FVC also improved significantly. Postoperative IMT improved the MIP and peak flow rate values, but the evidence was less robust than with preoperative interventions. We observed high heterogeneity across studies for several outcomes and found evidence of publication bias for some postoperative measures.

Conclusion: Both preoperative and postoperative IMT offer benefits for patients undergoing operations, especially by enhancing respiratory muscle strength and potentially reducing hospital stays. However, the presence of heterogeneity and publication bias underscores the need for further standardized research to consolidate these findings and standardize IMT protocols for optimal patient outcomes.