title: Association Between Emphysema Score, Six-Minute Walk and Cardiopulmonary Exercise Tests in COPD.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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).
  
  
  RESULTS
  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 VO(2) max (r=-0.514, p<0.05) and anaerobic threshold (r=-0.595, p<0.01) of cardiopulmonary exercise.
  
  
  CONCLUSIONS
  These results suggest that COPD associated with emphysema on HRCT is characterized by more severe lung function impairment, greater exercise impairment and cardiopulmonary dysfunction.
authors.affiliation: Pulmonary Medicine Research Center, Department of Thoracic Medicine, Chang Gung Memorial Hospital, Taipei, Taiwan, 199 Tun-Hwa North Road, Taipei, Taiwan.
authors.forename: Li-Fei
authors.initials: LF
authors.lastname: Chen
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Wang
authors.forename: Pai-Chien
authors.initials: PC
authors.lastname: Chou
authors.forename: Shu-Chuan
authors.initials: SC
authors.lastname: Ho
authors.forename: Wen-Ching
authors.initials: WC
authors.lastname: Joa
authors.forename: Te-Fang
authors.initials: TF
authors.lastname: Sheng
authors.forename: Han-Pin
authors.initials: HP
authors.lastname: Kuo
keywords: Chronic obstructive pulmonary disease; High-resolution computed tomography; Inspiratory capacity.; Six-minute walk test; cardiopulmonary exercise test