Domiciliary Positive Expiratory Pressure on Pulmonary Function and Exercise Capacity in Patients with Chronic Obstructive Pulmonary Disease

Background/Purpose: This study assessed how positive expiratory pressure (PEP) affected pulmonary function, functional capacity, and subjective cough difficulty in individuals with chronic obstructive pulmonary diseases (COPD). Methods: This was a prospective, randomized, controlled study. Subjects were recruited from an outpatient department at a university hospital. Thirty-two patients with COPD were allocated to either PEP+FET (forced expiratory technique) group (n=16) or FET only group (n=16). Subjects in PEP+FET and FET groups were in a clinically stable condition before and during the study. Subjects in the PEP+FET group received PEP breathing using a mouth adjunct to FET, and the FET group was administered FET for 4 weeks only. Patients received weekly follow-up during the study period. Pulmonary function, 6-minute walk tests, and subjective cough difficulty scores were measured before and after the 4-week interventions. Results: Subjects in the PEP+FET group had a significantly increased diffusing capacity (DLCO) compared to preintervention (p<0.05) and after intervention in the FET group (p<0.05). DLCO significantly increased in the PEP+FET group from 18.0±7.3 to 20.1±7.2mL/min/mmHg. The 6-minute walking distance (6MWD) also increased significantly from 516.8±94.1 to 570.6±60.4m in the PEP+FET group (p<0.001) after intervention, compared to that for the FET group (p<0.05). Additionally, the PEP+FET group had significantly lower cough difficulty scores compared to those at baseline and in the FET group. Conclusion: Four-week PEP therapy as an adjunct to FET further enhanced DLCO and 6MWD, and reduced cough difficulty compared to FET only in COPD patients with mucus hypersecretion.