Fig. 2From: Efficacy and safety of long-term use of a positive expiratory pressure device in chronic obstructive pulmonary disease patients, a randomized controlled trialFlow of recruitment of study subjects. A total of 25 subjects were eligible for inclusion and underwent randomization in the study, with 12 subjects in the control group (sham- PEP device) and 13 subjects in the intervention group (PEP device)Back to article page