Objective To evaluate the effects of inhaled bronchodilators on respiratory mechanics in moderate and severe chronic obstructive pulmonary disease（COPD） patients during eupnea.Methods Twenty moderate to severe COPD subjects were divided into three groups.Lung function，Borg score，breathing pattern and respiratory mechanics indexes were measured at baseline and 30 min after inhaled placebo，salbutamol 400 μg (or ipratropium 80 μg)，and ipratropium 80 μg (or salbutamol 400 μg) in sequence at interval as specified in different groups.Results In all groups，inhaled bronchodilators improved lung function (FEV1，FVC，IC) (Plt;0.05)，decreased Pdi，Peso，PTPdi，PTPeso and Raw (Plt;0.05，respectively)，in comparison with placebo.The reduction of PTPeso was positively correlated with the reduction of Peso (r=0.713，Plt;0.01）and Raw (r=0.602，Plt;0.01).Borg score decreased after inhaled bronchodilators (Plt;0.05).The reduction of dyspnea was positively correlated with the reduction of inspiratory work of breathing (ΔPTPeso%) (r=0.339，Plt;0.05) and Raw (ΔRaw) (r=0.358，Plt;0.05)，while was not associated with the changes of FEV1，FVC and IC.Conclusions In COPD patients，inhaled bronchodilators can reduce inspiratory work of breathing and airway resistance，the reduction of inspiratory work of breathing contributed to the reduction of airway resistance.Alleviation of dyspnea by inhaled bronchodilators is suggested to be ascribed to reduction of airway resistance and inspiratory work of breathing.
小气道病变曾经是全球呼吸界研究的热点，许多肺功能测定方法和指标被用于小气道功能的诊断，其后热度骤减，最近又引起一些学者的重视。
0bjective To evaluate the efficacy of FEV6 and FEV1／FEV6 as surrogates for FVC and FEV1／FVC in the spirometric diagnosis of airway obstruction，and to determine the fixed cut-off point of FEV1／FEV6 which can be used as an alternative for FEV1／FVC lt; 70％.Methods Spirometry measurements were perform ed in 128 participants．FEV1，FEV6，FVC，FEV1％pred，FVC％pred，FEV1／FVC and FEV1／FEV6 were measured and analyzed.FEV1／FVClt;70％ was used as the“gold standard”。Severity of obstruction was based on FEV ％ pred．From ROC curve analysis，the FEV1／FEV6 ratio，which corresponded to optimal combination of sensitivity and specificity，was determined．Correlation between FEV1／FVC and FEV1／FEV6 was studied．Results Of 128 participants，there were 65(51％)with FEV1／FVC ≥70％ ．Of the 63 participants with FEV1／FVC lt;70％ ，there were 5 with FEV1／FEV6 between 70.09％ to 71％。There was no significant difference between the mean value of FVC and that of FEV ．Lifear correlation was revealed between FEV1／FVC and FEV1／FEV6 with the value close to 1(r=0.9979，Plt;0.0001)．From ROC curve analysis，the FEV1／FEV6lt;71.14％ was the best cut-off point coresponding to FEV1／FVC lt;70％ ．Conclusion These results suggest that FEV1／FEV6 is a valid alternative to FEV1／FVC for spirometric diagnosis of airw ay obstruction．There is a b corelation between FEV1／FEV6 and FEV1／FVC．