Abstract: Objective To explore the correlation of diffusion of lung for carbon monoxide(DLCO) with exercise tolerance, dyspnea and ventilation efficiency in the patients with chronic obstructive pulmonary disease(COPD). Methods A total of sixty patients with stable COPD were divided into normal DLCO group and low DLCO group according to the results of diffusion capacity per unit alveolar volume(DLCO/V_A) in the first static pulmonary function examination at the time of enrollment. The static pulmonary function parameters of the two groups were collected and exercise tolerance, ventilation efficiency were tested by cardiopulmonary exercise test(CPET). The dyspnea scale(mMRC) was used to evaluate dyspnea. Pearson correlation analysis and liner regression were used to evaluate the correlation of DLCO with exercise tolerance, dyspnea and ventilation efficiency. Results The ratio of DLCO to predicted value [(DLCO/V_A)/pred], Peak Load, peak oxygen uptake to predicted value(Peak VO₂/pred), peak oxygen uptake per kilogram of body weight(Peak VO₂/kg) in the low DLCO group were lower, while CO₂ ventilation equivalent at anaerobic threshold( EQCO₂@AT), mMRC score were higher than those in the normal DLCO group(P<0.01). Correlation analysis showed (DLCO/V_A)/pred was positively correlated with Peak Load, Peak VO₂/pred and Peak VO₂/kg, while EQCO₂@AT and mMRC score showed negative correlation with (DLCO/V_A)/pred(P<0.05). Multiple linear regression analysis showed that (DLCO/V_A)/pred was an independent predictor of respiratory distress, exercise endurance and ventilation efficiency in COPD patients(P<0.05). Conclusions DLCO is related to dyspnea, exercise endurance and ventilation efficiency in the patients with COPD.

Key words: chronic obstructive pulmonary disease, diffusion of lung for carbon monoxide, sports endurance, ventilation efficiency, dyspnea