Effect of respiratory muscle training on diaphragm function in stroke patients: a systematic review and meta-analysis

Objective This meta-analysis aimed to assess the effectiveness of respiratory muscle training (RMT) in restoring diaphragm function after a stroke. Methods We conducted a comprehensive search for studies investigating the impact of RMT on diaphragm function in post-stroke patients that were published in the China National Knowledge Infrastructure, Wanfang Data, PubMed, Embase, Cochrane Library, Web of Science, Physiotherapy Evidence Database and ClinicalTrials.gov databases between inception and April 2023. Six reviewers independently screened eligible studies, extracted data and assessed methodological quality. The results were analysed using mean differences (MDs) with 95% confidence intervals (CIs), and heterogeneity was assessed using the chi-squared test and I 2 statistic. Results This meta-analysis included 6 studies comprising 246 patients, with methodological quality ranging from poor to excellent. We observed significant differences in diaphragm mobility on the affected side after a stroke (MD = 1.32, 95% CI: 0.96–1.67; p < 0.00001) as well as in affected side diaphragm thickness (DT) at inspiration (A-DTI) (MD = 0.08, 95% CI: 0.03–0.14; p = 0.002), affected side DT at expiration (A-DTE) (MD = 0.01, 95% CI: 0.00–0.02; p = 0.13), non-A-DTI (MD = 0.03, 95% CI: 0.02–0.04; p < 0.00001), non-A-DTE (MD = 0.01, 95% CI: −0.01–0.02; p = 0.56) and affected side diaphragm thickening fraction (DTF) (MD = 47.32, 95% CI: 11.04–83.60; p = 0.01) non-affected DTF (MD = 15.47, 95% CI: −12.19–43.13; p = 0.27). Conclusion Respiratory muscle training can enhance diaphragm function in post-stroke patients, encompassing improvements in diaphragm mobility, thickness and thickening fraction, particularly focusing on the affected side diaphragmatic function. Systematic review registration Trial registration CRD42022371157, available from https://www.crd.york.ac.uk/PROSPERO/view/CRD42022371157 .