Inspiratory muscle training improves respiratory muscle strength, functional capacity and quality of life in patients with chronic kidney disease: a systematic review

Questions: Does inspiratory muscle training improve respiratory muscle strength, functional capacity, lung function and quality of life of patients with chronic kidney disease? Does inspiratory muscle training improve these outcomes more than breathing exercises? Design: Systematic review and meta-analysis of randomised trials. Participants: People with chronic kidney disease undergoing dialysis treatment. Intervention: Inspiratory muscle training versus sham or no inspiratory muscle training, and inspiratory muscle training versus breathing exercises. Outcome measures: The primary outcomes were: maximal inspiratory pressure, maximal expiratory pressure, and distance covered on the 6-minute walk test. The secondary outcomes were: forced vital capacity, forced expiratory volume in the first second (FEV1), and quality of life. Results: The search identified four eligible studies. The sample consisted of 110 participants. The inspiratory muscle training used a Threshold (R) or PowerBreathe (R) device, with a load ranging from 30 to 60% of the maximal inspiratory pressure and lasting from 6 weeks to 6 months. The studies showed moderate to high risk of bias, and the quality of the evidence was rated low or very low, due to the studies' methodological limitations. The meta-analysis showed that inspiratory muscle training significantly improved maximal inspiratory pressure (MD 23 cmH(2)O, 95% CI 16 to 29) and the 6-minute walk test distance (MD 80 m, 95% CI 41 to 119) when compared with controls. Significant benefits in lung function and quality of life were also identified. When compared to breathing exercises, significant benefits were identified in maximal expiratory pressure (MD 6 cmH(2)O, 95% CI 2 to 10) and FEV1 (MD 0.24 litres 95% CI 0.14 to 0.34), but not maximal inspiratory pressure or forced vital capacity. Conclusion: In patients with chronic renal failure on dialysis, inspiratory muscle training with a fixed load significantly improves respiratory muscle strength, functional capacity, lung function and quality of life. The evidence for these benefits may be influenced by some sources of bias. (C) 2017 Australian Physiotherapy Association. Published by Elsevier B.V.