| BackgroundChronic obstructive pulmonary disease(COPD)is one of the four major chronic diseases in China.Small airway disease and destruction of lung parenchyma(emphysema)are important pathogenesis of COPD.Numerous studies have confirmed that small airway lesions occur in the early stage of COPD before emphysema,and timely assessment and effective detection of small airway lesions have important and far-reaching effects on early diagnosis and efficient prevention and treatment of COPD.Up to now,lung function still plays an indispensable role in small airway function evaluation.In clinical practice,FEFso,FEF75 and MMEF are mostly used as the diagnostic criteria for small airway dysfunction,with 2 or more of the 3 indicators declining.FEV3 is an indicator of pulmonary ventilation function that has received more attention in recent years.In the case of small airway lesions,the exhaled air volume increases after 3 seconds of exhalation due to the decrease of force independent zone flow rate,resulting in the decrease of FEV3/FVC.Therefore,FEV3/FVC may become a more sensitive index for the diagnosis of early airway obstruction in COPD,and it has the advantages of low variability and high sensitivity compared with the flow rate index,but there is no research to confirm the significance of FEV3/FVC in the evaluation of small airway lesions.This study attempts to explore the significance of FEV3/FVC in the assessment of small airway lesions through case-control studies with large samples.ObjectiveTo explore the value of FEV3/FVC in the evaluation of small airway lesions,and to provide a basis for adding new and more sensitive indicators in clinical application.Methods511 cases of pulmonary funcation test and quantitative CT scan results that was inspected in Qilu Hospital of Shandong University from Dec.2017 to Dec.2018 were involved in this statistical analysis.According to the admission criteria,the patients were divided into three groups:non-smoking group with normal ventilation function(n=241),smoking group with normal ventilation function(n=122),and mild to moderate COPD group(n=148).The results of pulmonary ventilation function indexes,small airway function indexes and quantitative CT airway parameters in each group were compared.The correlation between FEV3/FVC and FEF50%pred,FEF75%pred,MMEF%pred,FEF1%pred,mMRC score,CAT score and the airway wall index measured by quantitative CT was further analyzed.The sensitivity of FEV3/FVC to small airway lesions in smokers was compared with conventional clinical practice whcih use small airway flow index.Results1.In the non-smoking population with normal ventilation function,FEV3/FVC is negatively correlated with age(r=-0.525,P<0.001),and the coefficient of variation is significantly lower than the flow rate index related to small airway function2.The FEV3/FVC of smokers with normal lung ventilation function was significantly lower than that of healthy non-smokers,and higher than that of patients with mild to moderate COPD.Among smokers with normal FEV1/FVC,87.70%showed decreased FEV3/FVC3.FEV3/FVC was positively correlated with FEF50%pred(r=0.737,P<0.001),FEF7;%pred(r=0.662,P<0.001)and MMEF%pred(r=0.744,P<0.001)4.WA%and Pi 10 in the smoking group with normal ventilation function were significantly higher than those in the non-smoking group with normal ventilation function.The WA%of the smoking group was lower than that of the mild-moderate copd group.FEV3/FVC was negatively correlated with WA%(r=-0.440,P<0.001).ConclusionsThe decrease of FEV3/FVC indicates the possibility of small airway lesions,which can be used as one of the indicators for routine pulmonary ventilation function examination. |
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