Significance And Value Of Forced Vital Capacity (FVC) Reduction In Long-term Management Of Children Asthma

Objective:The typical changes of pulmonary function in asthmatic children are obstructive ventilation dysfunction with the decrease of FEV1/FVC and FEV1,but some asthmatic children show forced vital capacity?FVC?reduction.Adult studies suggest that reduced FVC in asthmatic patients may be associated with premature airway closure?gas trapping?,poor asthma control and poor prognosis in asthmatic patients,but there is no child related study.The purpose of this study was to investigate the clinical features of asthmatic children with reduced FVC,and to provide evidence for clinical interpretation of pulmonary function in children.Methods:From March 2015 to February 2018,children with bronchial asthma diagnosed at Shengjing Hospital affiliated to China Medical University and who had completed routine pulmonary ventilation tests were studied.The diagnosis was in accordance with the"guidelines for the diagnosis and Prevention of bronchial Asthma in Children"in2016 in China,and the quality control of pulmonary function examination was in line with the criteria of"Children's Pulmonary function Series guidelines?2?:lung Volume and ventilation function"in 2016 in China.According to the results of pulmonary function examination,the children were divided into two groups:restrictive group ?FEV1/FVC?80%and FVC%pred<80%?and obstructive group?FEV1/FVC<80%and FEV1%pred<80%?.The differences of basic information,demographic data,pulmonary function index,serum total IgE,fraction of nitric oxide in exhaled air?FeNO?,the duration of disease,state of illness?acute asthma attack?,the number of exacerbations within one year were analyzed retrospectively.Results:After screening,74 children were included in the restriction group and 183 in the obstructive group.The FEV1/FVC and FVC%pred in the restriction group were89.48±5.33and 70.29±8.42%respectively,and the FEV1/FVC and FVC%pred in the obstruction group were 71.71±5.19 and 87.18±6.34%respectively?P<0.001?.The FEV1%pred of the two groups were 74.36±10.34%and 73.74±5.77%respectively?P>0.05?.The FEF50%,FEF75%,FEF_25%-75%and SVC/FVC of the restriction group were significantly higher than that of the obstructive group?P<0.001?.After Bronchodilation test,the improvement rates of FEV1 were 7.26±7.52%and 14.95±10.95%in the control group and the occlusion group respectively?P<0.05?,the improvement of FVC were 7.78±9.8%and 2.62±5.94%,the improvement of FEF_25%-75%were 17.13±26.83%and 40.77±31.8%in two groups respectively?P<0.05?.There was a significant difference between the two groups in total serum IgE?P<0.05?.There was no significant difference between the two groups in sex,age,height,body mass index?BMI?,FeNO,the duration of disease,number of acute attacks within 1 year and standardized treatment time?P>0.05?.After standardized inhaled hormone therapy,FVC of 48?64.86%?children in the restriction group returned to normal in half a year,16 cases?21.6%?had decreased FVC for more than half a year,10 cases?13.5%?had decreased FVC for more than one year.Conclusion:The pulmonary function of some asthmatic children showed that only FVC was decreased,but there was no typical obstruction.The ratio of SVC/FVC in these children increased,suggesting that there might be premature airway closure.The reduction of FVC in asthmatic children is reversible,while inhalation of bronchiectasis can improve FVC,on the other hand,standardized inhaled glucocorticoid therapy can significantly improve the reduction of FVC.In the bronchodilation test,children with asthma should not only pay attention to the improvement of FEV1,but also have some value in FVC improvement.The causes of FVC reduction in asthmatic children still need to be further studied,on the one hand,the total lung capacity can be examined simultaneously,and a large sample of prospective in-depth study is needed.