Evaluation of respiratory muscle training interventions on pulmonary function in critical care: a systematic review and meta-analysis

Background: A meta-analysis of randomized controlled trials (RCTs) up to July 2024 evaluated the efficacy of respiratory muscle training (RMT) on pulmonary function in critically ill patients. Methods: The Ovid Medline was searched for RCTs (in English) examining RMT or related interventions (e.g., inspiratory/expiratory muscle training, non-invasive support) on respiratory muscle strength (e.g., maximum inspiratory (PImax), maximum expiratory (PEmax) and clinical outcomes. Methodological quality followed Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Effect sizes and 95% confidence intervals (CI) were calculated using a random-effects model, with heterogeneity assessed using I2 statistics. Results: Data from six RCTs, encompassing a total of 299 participants, were included in the analysis, among whom 152 were allocated to intervention groups and 147 to control groups. Despite the heterogeneity of the interventions, all shared the common objective of enhancing pulmonary function parameters, particularly PImax and PEmax, which serve as indicators of respiratory muscle strength. A high degree of heterogeneity (I2 = 99%) was observed, likely due to variations in patient populations, the types of intervention modalities employed (e.g., high-flow oxygen therapy, non-invasive ventilation modes, electrical stimulation) and differences in treatment durations. Nonetheless, the overall effect size was positive (13.26, 95%CI: 3.08 to 23.44), suggesting that these interventions effectively improve pulmonary function. Conclusions: This meta-analysis demonstrates that RMT interventions significantly improve pulmonary function in critically ill patients. However, the diversity of interventions and reliance on a single database (Ovid Medline) may limit the comprehensiveness of the findings. Future research should employ a more targeted Population, Intervention, Comparison, Outcomes and Study design (PICOS) framework, incorporate additional databases such as Cochrane Central, and standardize intervention protocols to enhance the clarity and comparability of outcomes. Clinical Trial Registration: INPLASY2024100041.

Lung; Respiratory interventions; Pulmonary function; Exercise capacity; Meta-analysis

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