Effects of respiratory muscle training on cough function in neurological disorders: A systematic review with meta-analysis

Abstract

BACKGROUND: Patients with neurological disorders can present the weakness of respiratory muscle and impaired cough function. Previous studies have shown that respiratory muscle strength training (RMT) is an effective method of improving the strength of respiratory muscle. The effects of RMT on cough function remain controversial. OBJECTIVE: We aimed to analyze randomized controlled trials (RCTs) that investigated the effects of RMT on cough function of patients with neurological disorders. METHODS: Pubmed, Medline, Embase, and the Cochrane Library were searched electronically for RCTs. Two reviewers independently performed data extraction and quality assessment. Data were analyzed by using RevMan 5.3 software of The Cochrane Collaboration. RESULTS: Five studies with 185 participants were included. The mean PEDro score was 6.2 (range 5 to 7), showing moderate methodological quality. Random-effects meta-analyses showed that respiratory muscle training improved peak expiratory cough flow of voluntary cough by 2.16 (95% CI 1.16 to 3.17) and involuntary cough by 2.84 (95% CI 1.29 to 4.39), with statistical significance (P < 0.0001, P = 0.0003). The experimental group had an improvement of 0.19 cmH2O (95% CI –0.12 to 0.5) on the maximal inspiratory pressure, 0.09 cmH2O (95% CI –0.23 to 0.42) on the maximal expiratory pressure, but with no statistical significance (P = 0.23, P = 0.58) between groups. CONCLUSION: Respiratory muscle training was considered as an effective method for improving cough function. However, this review was insufficient to conclude whether respiratory muscle training was effective in improving inspiratory and expiratory muscle strength, this was opposite with previous meta-analysis. These effects might due to the small samples and different diseases.