Respiratory Muscle Training Reduces Respiratory Complications and Improves Swallowing Function After Stroke: A Systematic Review and Meta-Analysis

Abstract

Objective: To investigate whether respiratory muscle training is capable of reducing the occurrence of respiratory complications and improving dysphagia (swallowing or cough function) after stroke.

Data sources: Cochrane Library, Excerpta Medical Database (EMBASE), PUBMED, and Web of Science were searched for studies published in English; the China Biology Medicine (CBM), China Science and Technology Journal Database (VIP), China National Knowledge Infrastructure (CNKI), and Wanfang Database were searched for studies published in Chinese up to August 10, 2021.

Study selection: Eleven randomized control trials (RCTs) (N=523) met the inclusion criteria were included in this systematic review.

Data extraction: Data and information were extracted by two reviewers independently and disagreements was resolved by consensus with a third coauthor. Primary outcome was the occurrence of respiratory complications, secondary outcomes would be represented by swallowing and cough function. The quality of each included RCT were assessed by Cochrane risk-of-bias criteria and the GRADE evidence profile was provided to present information about the body of evidence and judgments about the certainty of underlying evidence for each outcome.

Data synthesis: Respiratory muscle training reduced the risk of respiratory complications (relative risk, 0.51; 95% confidence interval [CI], 0.28-0.93; I²=0%; P=.03; absolute risk difference, 0.068; number need to treat, 14.71) compared with no or sham respiratory intervention. It also decreased the liquid-type Penetration-Aspiration Scale scores by 0.81 (95% CI, -1.19 to -0.43; I²=39%; P<.0001). There was no significant association between respiratory muscle training and Functional Oral Intake Scale (FOIS) scores, cough function: increased FOIS scores by 0.47 (95% CI, -0.45 to 1.39; I²=55%; P=.32), decreased peak expiratory cough flow of voluntary cough by 18.70 L per minute (95% CI, -59.74 to 22.33; I²=19%; P=.37) and increased peak expiratory cough flow of reflex cough by 0.05 L per minute (95% CI, -40.78 to 40.87; I²=0%; P>.99).

Conclusion: This meta-analysis provided evidence that respiratory muscle training is effective in reducing the risk of respiratory complications and improving dysphagia by reducing penetration or aspiration during swallowing liquid bolus after stroke. However, there was no sufficient evidence to determine that respiratory muscle training improves cough function. Additional multicenter studies using larger patient cohorts are required to validate and support these findings. Furthermore, long-term follow-up studies should be performed to measure outcomes, while avoiding bias due to confounding factors such as heterogeneity of the etiologies of dysphagia.

Keywords: Breathing exercises; Deglutition disorders; Rehabilitation; Stroke; Systematic review.