Effects of Progressive Inspiratory Muscle Training on Lung Volume and Respiratory Strength in Patients With Pre-Dialysis Chronic Kidney Disease.

Chronic kidney disease can present changes in thoracic cavity volume and respiratory muscle weakness, even in the pre-dialysis stage. However, there is little evidence on the effects of inspiratory muscle training in these patients. This was a randomized clinical trial which comprised patients with Chronic Kidney Disease in stages 3, 4, and 5 undergoing conservative treatment, allocated experimental group (EG) with progressive loading (up to 50% of maximal inspiratory pressure [MIP]) and control group (CG) with a fixed load (5 cmH2O) and no load progression performed daily for 8 weeks. The outcomes assessed were thoracic cavity volumes, as measured by optoelectronic plethysmography, and inspiratory and expiratory respiratory muscle strength. A total of 30 patients completed the study. All volumes significantly increased at the end of the protocol with a large effect size, but only the pulmonary thoracic cavity volume showed a significant interaction (F = 3.698; p = 0.042). There was an increase in inspiratory muscle strength in the EG (73.88-90.35 cmH2O; p < 0.001) and in the CG (70.85-86.92 cmH2O; p = 0.001), as well as in expiratory muscle strength in the EG (97.71-108.53 cmH2O; p = 0.001) and in the CG (80.69-94.77 cmH2O; p = 0.004). Daily IMT increased thoracoabdominal volumes, particularly pulmonary rib cage volume in the progressive-load group, as well as respiratory muscle strength in patients with pre-dialysis CKD. However, progressive-load IMT was not superior to minimal-load training.