Influence and significance of tiotropium on inspiratory capacity in patients with stable chronic obstructive pulmonary disease.

Objective To observe the influence of tiotropium on inspiratory capacity(IC)in patients with stable COPD and investigate the value of IC in evaluating therapeutic effect of bronchodilators.Methods A 12-week,randomized,double-blind,placebo-controlled study was conducted in 60 patients with stable COPD,patients in A group by haling tiotropium and those in B group by inhaling placebo.At each of the visits days 1,43(about 6 weeks)and 85(about 12 weeks),forced expiratory volume in one second(FEV_1),percentage of FEV_1 and predict value[FEV_1(%)],forced expiratory volume(FEV),FEV_1/FVC and IC were measured.Results Compared with B group,FEV_1 in A group increased significantly in week 6(t=2.018,P=0.048),but there was no statistical significance between them in week 12(P0.05).FEV_1(%)increased in week 6 and 12,but there was also no statistical significance between two groups(P0.05).FVC increased significantly in week 6 and 12(t=2.762,P =0.008;t=2.255,P =0.029,respectively).There was no statistical significance in FEV_1/FVC between two groups.IC increased significantly in week 6 and 12(t =3.204,P =0.002;t =3.109,P=0.003,respectively).Conclusion Inhaling tiotropium increases IC in patients with stable COPD.As lung function targets judging limit extent of airflow in patients with COPD,FEV_1/FVC and FEV_1(%)are not sensitive in evaluating therapeutic effect of bronchodilators.IC is more reliable than other targets in evaluating therapeutic effect of bronchodilators.