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

OBJECTIVE To investigate if respiratory muscle training is capable of reducing the occurrence of respiratory complications and improving dysphagia (swallowing or cough function) after stroke? DESIGN Systematic review of randomized control trials based on the Cochrane guidelines. PARTICIPANTS Patients (> 18 years old) were diagnosed with stroke. INTERVENTION Respiratory muscle training aimed at increasing respiratory muscles' strength by using the threshold resistance trainer or flow-oriented resistance trainer. OUTCOME MEASURES Respiratory complications, swallowing and cough function. RESULTS Eleven trials (n=523 participants) were included . Respiratory muscle training reduced the risk of respiratory complications (RR0.51, 95%CI 0.28 to 0.93, I2 = 0%,P=0.03, ARD =0.068, NNT=14.71) compared with no/sham respiratory intervention. It also decreased the liquid type PAS scores by 0.81 (95% CI -1.19 to -0.43, I2 = 39%, P<0.0001). There was no significant association between respiratory muscle training and FOIS scores, cough function:increased FOIS scores by 0.47 (95%CI -0.45 to 1.39, I2 = 55%, P=0.32), decreased PECF-VC by 18.70 L/min (95%CI -59.74 to 22.33, I2 = 19%, P=0.37) and increased PECF-RC by 0.05 L/min (95% CI -40.78 to 40.87 I2 = 0%, P=1.00) . 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 multi-center 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, at the same time avoiding bias due to confounding factors such as heterogeneity of the etiologies of dysphagia.