Comparison of expiratory flow-volume and lung capacity response to bronchodilator in patients with chronic obstructive pulmonary disease

Objective To evaluate the changes of forced expiratory volume in one second(FEV1),forced vital capacity(FVC),inspiratory capacity(IC) and residual volume(RV) after inhaling bronchodilators in patients with chronic obstructive pulmonary disease(COPD).Methods A total of 526 patients with COPD in stable period and without heart failure were divided into mild group(n=103),moderate group(n=294) and severe group(n=129) according to GOLD criteria.All the patients were compared the changes of FEV1,FVC,IC and RV levels before and after inhaling bronchodilators.Results The levels of FEV1,FVC and IC were higher and RV was lower after inhaling bronchodilators showing significant differences in comparison with before inhaling bronchodilators(P0.05).The improvement rate was 18.1% of FEV1,31.9% of FVC,31.7% of IC and 60.3% of RV,respectively.There were significant differences between each two parameters(P0.05) except between FVC and IC(P0.05).The improvement rate of RV was obviously higher than that of FEV1,FVC,and IC in these three groups(P0.05),and was higher in severe group(68.2%) than that in mild group(47.6%) and moderate group(61.2%).Conclusion The response of lung capacity to bronchodilators is more significant than expiratory flow volume in COPD patients.With the increase of COPD severity,the value of FEV1 response becomes lower.And RV is a obvious parameter to bronchodilator.