Different Phenotypes of Respiratory Muscle Strength Influence Exercise Capacity and Health-Related Quality of Life in COPD Patients

Hsiang-Yu Huang ； Po-Chun Hsieh ； Mei-Chen Yang ； I-Shiang Tzeng ； Yao-Kuang Wu ； Chou-Chin Lan

《胸腔醫學》 36卷1期 (2021/03) Pp. 1-11

摘要

Objective: The respiratory muscles are the force that drives respiration. Different phenotypes of respiratory muscle strength (RMS) can have an effect on chronic obstructive pulmonary disease (COPD). However, the effects of phenotypes of RMS on exercise capacity and health-related quality of life (HRQL) are unclear. Methods: TA total of 85 subjects with stable COPD were included over a 2-year period and comprehensively evaluated by an RMS test, spirometry, cardio-pulmonary exercise test, and St. George's Respiratory Questionnaire (SGRQ). If the maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) of the subjects were lower than the cut-off value, this was defined as inspiratory or expiratory muscle weakness. Patients were divided into 4 different phenotypes: type I with normal RMS, type II with inspiratory muscle weakness, type III with expiratory muscle weakness, and type IV with both inspiratory and expiratory muscle weakness. We compared the parameters of exercise capacity, HRQL, and lung function among these phenotypes. Results: Sixty-one subjects were type I (MIP 74.2±21.8 cmH_2O; MEP 123.2±31.8), 6 were type II (MIP 30.8±4.4 cmH_2O; MEP 96.8±22.9), 10 were type III (MIP 52.8±24.9 cmH_2O; MEP 62.1±8.9 cmH_2O), and 8 were type IV (MIP 32.8±8.1 cmH_2O; MEP 57.9±20.7 cmH_2O). Type IV subjects had the lowest tidal volume (494.2±127.3 ml, p = 0.002), highest respiratory rate (27.5±11.4 breaths/min, p ＜ 0.001), highest degree of dyspnea, poorest SGRQ and lowest exercise capacity. Conclusion: RMS is an important factor in dyspnea, exercise capacity and HRQL. Subjects with inspiratory and respiratory failure had more dyspnea, poor exercise capacity and poor HRQL. Health care providers need to be aware of COPD patients with respiratory muscle weakness and carry out early intervention for them.

關鍵字

chronic obstructive pulmonary disease ； respiratory muscle strength ； exercise capacity ； health-related quality of life