title: [Association of oxygen uptake efficiency in exercise test with exercise capacity in patients with stable chronic obstructive pulmonary disease].
abstract: OBJECTIVE
  To explore the characteristics of oxygen uptake efficiency (OUE) in patients with chronic obstructive pulmonary disease (COPD), and to analyze the relationship between OUE and the exercise capacity.
  
  
  METHODS
  Pulmonary function test and cardiopulmonary exercise test were performed in 59 patients with stable COPD (grade I, n = 15; grade II, n = 16; grade III, n = 19; grade IV, n = 9) and 29 healthy volunteers of the same age. Their successive breathing respiratory exchange parameters were collected and analyzed. t test and χ(2) test were used for 2 sample comparison, while multiple comparisons among groups were performed by using single factor analysis of variance. Correlation analysis was done by Pearson correlation test.
  
  
  RESULTS
  Compared with the normal control group [(2.2 ± 0.4) L·min(-1)·lg(L·min(-1))(-1); (35 ± 4) ml/L], the OUES and OUEP of the COPD patient group [(1.9 ± 0.3) L·min(-1)·lg(L·min(-1))(-1); (31 ± 5) ml/L]were significantly lower (t = 4.57, 3.39, all P < 0.01) . The OUE of the grade I patients showed no significant difference compared with the normal control group (t = 0.36-1.49, all P > 0.05), while the OUES of the grade II-IV patients [(2.05 ± 0.26), (1.76 ± 0.28) and (1.63 ± 0.19) L·min(-1)·lg(L·min(-1))(-1)] decreased significantly compared to the normal control group [(2.23 ± 0.39) L·min(-1)·lg(L·min(-1))(-1); t = 2.42-5.26, all P < 0.05]. The OUEP and the OUE at the anaerobic threshold of the grade II-III patients [(31 ± 4) and (31 ± 5), (29 ± 5) and (29 ± 5) ml/L] decreased significantly compared to the normal control group [(35 ± 4) and (34 ± 4) ml/L, t = 2.18-4.83, all P < 0.05]. The OUES, OUEP and the OUE at the anaerobic threshold in COPD patients were correlated (r = 0.500-0.625, all P < 0.01) positively with the exercise tolerance (peak VO2% pred).
  
  
  CONCLUSIONS
  The oxygen uptake efficiency of patients with COPD is significantly reduced compared to that of the normal subjects, and is correlated positively with the exercise capacity.
authors.affiliation: The Medical College of Soochow University, Suzhou 215006, China.
authors.forename: Chang-wei
authors.initials: CW
authors.lastname: Wu
authors.affiliation: Department of Respiratory Medicine, Shanghai Pulmonary Hospital affiliated to Tongji University, Shanghai 200433, China, Email: jinmingliu_sh@hotmail.com.
authors.forename: Jin-ming
authors.initials: JM
authors.lastname: Liu
authors.forename: Wen-lan
authors.initials: WL
authors.lastname: Yang
authors.forename: Xing-guo
authors.initials: XG
authors.lastname: Sun
authors.forename: Dan-dan
authors.initials: DD
authors.lastname: Huang
authors.forename: Hai-jian
authors.initials: HJ
authors.lastname: Liu
authors.forename: Shu-juan
authors.initials: SJ
authors.lastname: Chen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism* / Q000503:physiopathology; D012129:Respiratory Function Tests