Discussion
dyspnea, COPD
COPD, DISEASE
To the best of our knowledge, this is the first randomized controlled trial to evaluate the effects of using PEP device during activities of daily living on exercise capacity in patients with COPD or Pre-COPD. The major findings of the present study are as follows: (1) Patients in the intervention group showed significant improvement in exercise tolerance after one month of using the PEP device (5 cmHDyspnea is a common symptom reported by patients with COPD, despite optimal medical management, the use of supplemental oxygen and PLB [Monteiro et al. indicated that a small improvement in DH observed with PEP might lead to greater exercise endurance and reduced dyspnea [Nicolini et al. indicated that PEP (5 cmHRegarding the safety of PEP devices, our study showed that daily use of PEP devices did not cause carbon dioxide (COThis study has some important limitations. First, the subject sample in our study was small, including subjects with a wide range of disease severity. It can be argued that the heterogeneity of the subjects could have affected the response to the intervention. Therefore, future studies should focus on a larger sample with a more homogeneous population, such as those with consistent disease severity, to avoid underestimating or overestimating the true effect of PEP devices. Second, the recommendation of 4 h of the use of PEP device has no real scientific background. Subjects may accept and tolerate an average of 4 h of PEP device use per day. However, further studies are needed to decide the duration of optimal use. Third, we do not know whether a longer study duration could have resulted in further improvement in lung function, and we expect future studies to clarify these clinically important questions. Fourth, the PEP device used in this study cannot currently be remotely monitored.