Association Between Emphysema Score, Six-Minute Walk and Cardiopulmonary Exercise Tests in COPD

Li-Fei Chen§, Chun-Hua Wang*, §, Pai-Chien Chou, Shu-Chuan Ho, Wen-Ching Joa, Te-Fang Sheng , Han-Pin Kuo#
Pulmonary Medicine Research Center, Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan, 199 Tun-Hwa North Road, Taipei, Taiwan

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© Chen et al.; Licensee Bentham Open.

open-access license: This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted, non-commercial use, distribution and reproduction in any medium, provided the work is properly cited.

* Address correspondence to this author at the 199 Tun-Hwa North Road, Taipei, Taiwan. Pulmonary Medicine Research Center, Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taiwan; Tel: 886 3 3281200, Ext. 8470; Fax: 886 3 3272474; E-mail:
# Kuo, H-P. contributed equally as the co-corresponding author.
§ Chen, L-F and Wang, C-H contributed equally to this project as co-first author.



High-resolution computed tomography (HRCT) has allowed in detection of airway wall abnormalities and emphysema, whose extent may correlate with the clinical severity of the disease in patients with chronic obstructive pulmonary disease (COPD). Six minute walk test (6MWT) and cardiopulmonary exercise test (CPET) can determine functional status.


A study was undertaken to investigate whether the extent of emphysema in COPD patients quantitatively confirmed by HRCT scoring was associated with distance walked, inspiratory capacity (IC) changes after exercise, anaerobic threshold of cardiopulmonary exercise and the BODE index (body mass index, airflow obstruction, dyspnea, exercise performance).


Seventeen patients with COPD underwent HRCT scanning, 6MWT and CPET. The emphysema score was highly correlated to forced vital capacity (FVC) (r=-0.748, p<0.001), forced expiratory volume in 1 second (FEV1) (r=-0.615, p<0.01), IC post exercise (r=-0.663, p<0.01) and dyspnea score post exercise (r=0.609, p<0.01), but was not associated with the BODE index. The distance walked during 6MWT was inversely correlated to emphysema score (r=-0.557, p<0.05). IC before exercise was highly related to the 6MWT. The change in IC after exercise was associated with the percent decline of oxygen saturation after exercise (r=0.633, p<0.01). Severity of lung emphysema in COPD patients was inversely correlated to VO2 max (r=-0.514, p<0.05) and anaerobic threshold (r=-0.595, p<0.01) of cardiopulmonary exercise.


These results suggest that COPD associated with emphysema on HRCT is characterized by more severe lung function impairment, greater exercise impairment and cardiopulmonary dysfunction.

Keywords: Chronic obstructive pulmonary disease, High-resolution computed tomography, Six-minute walk test, cardiopulmonary exercise test, Inspiratory capacity..