Therapeutic Effects of Respiratory Muscle Training in Patients with Chronic Obstructive Pulmonary Disease

Research Objectives: To investigate the improvement of cognition, lung function, clinical scores, and diaphragmatic muscle performance after respiratory muscle training in populations of chronic obstructive pulmonary disease (COPD) comorbid with mild cognitive impairment.

Design: This is a prospective randomized study with eight weeks of intervention

Setting: Participants were recruited from a tertiary referral center, and they were instructed to perform training at home with telephonic supervision every week

Participants: The inclusion criteria included: (1) a diagnosis of COPD, and (2) an mini mental state examination (MMSE) score between 23 and 27. The exclusion criteria were: (1) being unable to follow respiratory muscle training instructions or complete the questionnaires of our study due to cognitive impairment; (2) difficulty in completing cardiopulmonary exercise testing (CPET) due to high-risk cardiopulmonary diseases or orthopedic conditions; (3) a body mass index (BMI) of ≥30. Finally, 28 patients received both inspiratory and expiratory muscle training and 20 patients received inspiratory muscle training only.

Interventions: Participants were randomized into the full training (inspiratory plus expiratory muscle training) or the simple training group (inspiratory muscle training only) for a total of eight weeks.

Main Outcome Measures: Diaphragmatic thickness fraction and excursion examined through ultrasound; scores of MMSE, the COPD assessment test (CAT) and modified Medical Research Council (mMRC) scale; percentage of predicted FVC, FEV1, FEV1/FVC, DLCO, and DLCO/VA examined by pulmonary function test; dead space fraction (Vd/Vt) and minute ventilation to CO2 output (VE/VCO2) slope examined by CPET; and distance walked and changes in oxygen saturation and perceived exertion during six-minute walking test

Results: Respiratory muscle training significantly improved the diaphragmatic thickness fraction and excursion, lung functions, MMSE, CAT and mMRC scores. The difference between the full training and simple training group was not significant. Patients with FEV1>30% had more improvement in diaphragmatic thickness than those with FEV1 < 30%.

Conclusions: Expiratory muscle training could provide no further benefit to inspiratory muscle training. Additional study recruiting more patients with FEV < 30% could better validate our study results in clinical settings.

Author(s) Disclosures: Nothing to be disclosed