title: Chronic bronchitis leads to accelerated hyperinflation in COPD patients during exercise.
abstract: OBJECTIVE
  It is not known whether patients with chronic obstructive pulmonary disease (COPD) have a different exercise capacity with (CB(+) ) or without accompanying chronic bronchitis (CB(-) ).
  
  
  METHODS
  We conducted spirometry, a 6-min walk distance test and cardiopulmonary exercise test in 50 age-matched healthy control subjects, 45 COPD patients without CB (CB(-) ) and 37 COPD patients with CB (CB(+) ). A multiple regression model was established to identify factors independently associated with peak oxygen consumption ( V ˙ O 2 ).
  
  
  RESULTS
  Patients with and without CB had similar forced expiratory volume in 1 s (FEV1 ). CB(+) patients had a lower V ˙ O 2 . CB(+) and CB(-) participants had similar increases in tidal volume at peak exercise; however, CB(+) patients had an increased respiratory rate (RR). These patients reached the peak value for ratio of end-expiratory lung volume to total lung capacity (TLC) at a lower work load. A stepwise multiple linear regression analysis identified chronic bronchitis, FEV1 , diffusing capacity for carbon monoxide, the ratio of residual volume to TLC and serum tumour necrosis factor-α as independent predictors of peak V ˙ O 2 .
  
  
  CONCLUSIONS
  CB significantly lowers exercise capacity in COPD patients because of dynamic hyperinflation during exercise. The accelerated dynamic hyperinflation may contribute to increased airway and systemic inflammation in COPD patients.
authors: Department of Pulmonary and Critical Care Medicine, Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China.
authors: Wen
authors: W
authors: Zhang
authors: Haitao
authors: H
authors: Lu
authors: Liyue
authors: L
authors: Peng
authors: Xiaoxia
authors: X
authors: Ren
authors: Yong
authors: Y
authors: Lu
authors: Li
authors: L
authors: An
authors: Hong
authors: H
authors: Zhang
authors: Xiaoyue
authors: X
authors: Tan
authors: Xingguo
authors: X
authors: Sun
authors: Kewu
authors: K
authors: Huang
mesh_terms: D029481:Bronchitis, Chronic / Q000150:complications* / Q000503:physiopathology; D018450:Disease Progression; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000209:etiology* / Q000503:physiopathology; D013147:Spirometry; D014109:Total Lung Capacity
keywords: cardiopulmonary exercise test; chronic bronchitis; chronic obstructive pulmonary disease; dynamic hyperinflation; exercise capacity