High-Frequency Airway Oscillating Device for Respiratory Muscle Training in Subjects With COPD

COPD is characterized by expiratory flow limitation, which results in symptomatic dyspnea and reduced exercise capacity. Changes in breathing mechanics mean the respiratory muscles are unable to respond to the ventilatory demands, increasing the sensation of dyspnea. A high-frequency oscillating device has been developed to improve dyspnea in patients with COPD. We conducted a feasibility trial to gain insight into the potential for recruitment, retention, and study design for a future randomized controlled trial.

Symptomatic subjects with COPD were included on the basis of a Medical Research Council (MRC) score ≥ 3 and FEV₁/FVC < 0.70). Patients were excluded if they received pulmonary rehabilitation within the last 6 months. The intervention employed the device for 8 weeks, 3 times daily. Clinical outcomes included the MRC score, maximal expiratory and inspiratory pressures (P_Emax/P_Imax), the incremental shuttle walk test (ISWT), and the endurance shuttle walk test (ESWT).

We successfully recruited 23 subjects with established COPD (65.2% male, mean age 65 ± 5.03 y, mean % predicted FEV₁ 43.9 ± 16, mean FEV₁/FVC ratio 0.46 ± 0.13, and median [interquartile range] MRC 4 [3-5]). There was a significant change in MRC from 4 to 3 pre to post intervention (P = .003). There was a statistically significant difference in P_EmaxP < .008 and P_ImaxP = .044. There were no significant differences observed in the ISWT or ESWT.

This study design appeared feasible to proceed to a clinical effectiveness trial. The use of the device for 8 weeks showed a significant improvement in P_Emax, P_Imax, and reduced symptomatic dyspnea on the MRC dyspnea score. The results of this study should encourage a randomized controlled trial.