Effects of respiratory muscle training in chronic kidney disease patients on peritoneal dialysis: a pilot study

Introduction:
The strength of inspiratory and expiratory muscles in patients treated with peritoneal dialysis is lower than in haemodialysis patients and in those after kidney transplantation. The dialysate in the abdominal cavity increases intraabdominal pressure and disturbs diaphragm contraction.

Aim of the research:
To compare the effects of inspiratory muscle training (IMT) on respiratory and functional parameters in patients undergoing peritoneal dialysis.

Material and methods:
A randomised, unblinded trial was conducted. Subjects were randomly assigned to perform 6 weeks of IMT at 40% of maximal inspiratory pressure. Measurements were taken at baseline and 6 weeks after the intervention. Primary outcomes included functional capacity (assessed by 6-minute walk test), maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), and spirometry parameters.

Results:
Initially, a cohort of 37 peritoneal dialysis patients, with an average age of 51.3 years (95% CI: 47.1–55.5), underwent randomisation. The control group consisted of 18 participants, whereas the study group comprised 19 subjects. Owing to attrition prior to the conclusion of the 6-week duration, the control group was subsequently reduced to 11, and the study group to 18. Patients who underwent IMT showed significant improvement in PImax (p < 0.0001), PEmax (p = 0.048), and 6MWT distance (p = 0.01). Increases in systolic blood pressure (SBP, p = 0.036) and heart rate (HR, p = 0.045) induced by the 6MWT were less marked in the respiratory training group.

Conclusions:
Respiratory muscle training appears to enhance respiratory muscle strength, potentially improving exercise tolerance. Despite the attrition, our study provides valuable insights into the effects of IMT on respiratory and functional parameters in peritoneal dialysis patients.