Effect of respiratory training on swallowing function in swallowing disorders: a systematic review and meta-analysis

Purpose To determine the clinical efficacy of different respiratory training interventions on swallowing function in patients with swallowing disorders through the systematic review. Methods We reviewed the literature regarding the application of respiratory training therapy in patients with swallowing disorders, followed by a PRISMA search of published literature in five databases (PubMed, Web of Science, The Cochrane Library, CINAHL and EMBASE) in December 2022. Two reviewers performed study selection, quality evaluation, and risk of bias, followed by data extraction and detailed analysis. Results A total of six randomized controlled studies with a total sample size of 193 cases were included. Respiratory training improved swallowing safety (PAS ( n = 151, SMD = 0.69, 95% CI − 1.11 to − 0.26, I 2 = 36, p < 0.001)) and swallowing efficiency [residual ( n = 63, SMD = 1.67, 95% CI − 2.26 to − 1.09, I 2 = 23%, p < 0.001)] compared to control groups. The results of the qualitative analysis conducted in this study revealed that respiratory training enhanced hyoid bone movement but had no effect on swallowing quality of life. Conclusions Respiratory training interventions may improve swallowing safety and efficiency in patients with dysphagia. However, the level of evidence is low, and there is a limited amount of research on the effectiveness and physiology of this intervention to improve swallowing function. In the future, there is a need to expand clinical studies, standardize measurement tools, and improve study protocols.