Comparison Of Lung Volume Response With Airflow Response To Bronchodilator In Patients With Chronic Obstructive Pulmonary Disease

Objective: The study was carried out to evaluate the difference of FEV1response andlung volumes (FVC，IC and RV) response to bronchodilators in patients with COPDas welI as the impact of severity of COPD on the flow and volume reversibility.Methods: We studied the impacts of severity on flow and volume response of526subjects(79.1%male) with a post-bronchodilator FEV1/FVC<0.70, including103cases of stage I,294cases of stage II,129cases of stage III/IV by GOLD criteria. Allthe calculations and statistics were performed with the computer program, SPSSversion13.0. Statistical analysises adopt χ2test, t test, ANOVA, and calculate thevalues of odds ratio and95%confidence intervals for odds ratio. Values are reportedas means±SD unless otherwise specified. A p-value of <0.05was consideredsignificant in all analyses. A chi-square test for homogeneity was used to assess thedifferences between the proportions of gender within the entire cohort and eachGOLD stage. Differences between means across genders were examined using theunpaired t test. Comparisons across GOLD stages were analyzed using ANOVA.Results: FEV1, FVC and IC increased following bronchodilation,RV decreased(P<0.05)； Post-bronchodilator FEV1changed less than the FVC,IC and RV(P<0.05)；RV changed higher than the FVC and IC(P<0.05); The difference betweenFVC and IC was no statistically significant (P>0.05).The rate of significantlyimprovement was18.1%(FEV1),31.9%(FVC),31.7%(IC) and60.3%(RV),respectively. Except for the difference the rate of significantly improvement betweenFVC and IC,the differences among various parameters of the rate were statisticallysignificant(P <0.05).In all GOLD subgroups, the rate of significantly improvement inRV was obviously higher than the ones in FEV1,FVC,and IC (P <0.05). The rate ofsignificantly improvement in RV of the stages III/IV（88/129，68.2%）was obviouslyhigher than the ones in the stages （I49/103，47.6%）and I（I180/294，61.2%）(P <0.05).Conclusion: With increasing COPD severity, the responsiveness of lung Capacityreactions after bronchodilators is more significant than expiratory flow reaction. AsGOLD stage worsened, the FEV1response became less important while other lungvolume responses increased progressively. The most consistent physiologicalimprovement following acute bronchodilator therapy across GOLD stages wasreduced RV.