4. Discussion
respiratory and peripheral muscle weakness
This pilot randomized controlled study aimed to test the ease of use and the effectiveness on the strength of respiratory muscles and on the effort-dependent spirometric values of a home-based novel training using a tool to exercise ventilation based not only on an increase in air flow resistance but also in volumes.The trial was carried out in an ESKD population, where respiratory and peripheral muscle weakness is a systemic component, as reported in both in vivo and in vitro studies [The first finding of the present pilot study is the possibility of significantly improving the strength of the respiratory muscles with a simple tool easily employed at home by patients. In fact, both MIP and MEP values significantly increased in the RMT group but not in CON. The increase observed in the RMT group was approximately 25 cmHIn relation to respiratory function, in the present pilot trial, no significant improvements were observed for the FVC, FEV1 and MVV parameters, in contrast with the papers of Campos et al. [The second important finding of the present study is the significant effectiveness of training even if of shorter duration and lower intensity with respect to all the other protocols observed in the literature. Indeed, in this pilot trial, only 80 breathing cycles per nondialysis day were required for the patients, divided into eight complete breaths against resistance, followed by one minute resting pauses, to be repeated five consecutive times, twice per day. Several differences from the published literature are reported in terms of training modality, duration and intensity. At first, in this trial, the training was executed at home autonomously by the patients, as in only two other trials [The study has several limitations. First, the small sample size may have affected the significance of the results, as well the slight imbalances at baseline, particularly related to dialysis vintage. Quality of life was not directly measured in this pilot study. Moreover, the adherence of patients to the treatment was only reported on the daily diary, and was not confirmed by caregiver or monitored. Finally, patients of the RMT group decided autonomously whether to continue the training after the scheduled exercise period, potentially confounding the results observed at the follow-up.