Effects of dynamic hyperinflation on exercise capacity and quality of life in stable COPD patients

• Published in: The clinical respiratory journal Vol. 10; no. 5; pp. 579 - 588
• Main Authors: Zhao, Li, Peng, Liyue, Wu, Baomei, Bu, Xiaoning, Wang, Chen
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.09.2016; John Wiley & Sons, Inc
• Subjects: Aged; body composition; cardiopulmonary exercise test; Case-Control Studies; chronic obstructive; Chronic obstructive pulmonary disease; COPD assessment test; dynamic hyperinflation; exercise; Exercise - physiology; Female; Forced Expiratory Volume; Humans; Hyperinflation; Inspiratory Capacity; Lung - physiopathology; Male; Middle Aged; pulmonary disease; Pulmonary Disease, Chronic Obstructive - physiopathology; Quality of Life; Respiratory Function Tests; Total Lung Capacity; Walk Test - methods; body composition; COPD assessment test; pulmonary disease; dynamic hyperinflation; chronic obstructive; exercise; cardiopulmonary exercise test
• ISSN: 1752-6981; 1752-699X
• DOI: 10.1111/crj.12260

Background and Aims Dynamic hyperinflation (DH) is an important pathophysiological characteristic of chronic obstructive pulmonary disease (COPD). There is increasing evidence that DH has negative effects on exercise performance and quality of life. The objective of this study was to explore effects of DH on exercise capacity and quality of life in stable COPD patients. Methods Fifty‐eight COPD patients and 20 matched healthy individuals underwent pulmonary function test, 6‐min walk test and symptom‐limited cardiopulmonary exercise test (CPET). End‐expiratory lung volume/total lung capacity ratio (EELVmax/TLC) at peak exercise of CPET was evaluated, and EELVmax/TLC ≥ 75% was defined as ‘severe dynamic hyperinflation (SDH)’. Results Of the 58 patients studied, 29 (50.0%) presented with SDH (SDH+ group, EELVmax/TLC 79.60 ± 3.60%), having worse maximal exercise capacity reflected by lower peakload, maximal oxygen uptake (VO2max), maximal carbon dioxide output (VCO2max) and maximal minute ventilation (VEmax) than did those without SDH (SDH− group, EELVmax/TLC 67.44 ± 6.53%). The EELVmax/TLC ratio at peak exercise had no association with variables of pulmonary function and 6‐min walk distance (6MWD), but correlated inversely with peakload, VO2max, VCO2max and VEmax (r = −0.300~−0.351, P < 0.05). Although no significant differences were observed, patients with EELVmax/TLC ≥ 75% tended to have higher COPD assessment test score (15.07 ± 6.55 vs 13.28 ± 6.59, P = 0.303). Conclusions DH develops variably during exercise and has a greater impact on maximal exercise capacity than 6MWD, even in those with the same extent of pulmonary function impairment at rest.