The Value On Angle β Of Ascending Branch Of MEFV Curve Combined With FeNO In The Diagnosis And Treatment Of Asthma In School-aged Children

BackgroundBronchial asthma is a heterogeneous disease,which is usually characterized by chronic airway inflammation and is one of the most common respiratory diseases in childhood.It is involved by a variety of cells and cytokines,resulting in increased airway hyperresponsiveness and reversible airflow limitation.According to the incomplete statistics of the Global Initiative for Asthma(GINA),about 300 million children worldwide suffer from asthma,especially in developing countries,and the prevalence rate is on the rise.If asthmatic children is not diagnosed and treated in time,the course of disease can be prolonged,which can lead to irreversible airway stenosis and remodeling.Therefore,early identification and treatment of asthma is very important.Routine ventilation pulmonary function test and fractional exhaled nitric oxide(Fe NO),as objective auxiliary examinations of airflow limitation and airway inflammation,play an irreplaceable role in the diagnosis of asthma.A recent study has found that the angle β of the ascending branch of maximum expiratory flow volume(MEFV)curve(hereinafter referred to as angle β)can be used to evaluate the expiratory explosive force and the initial quality of the MEFV curve.At present,the indexes used to evaluate the expiratory explosive force are backward extrapolated volume(VBE)and VBE/forced vital capacity(FVC).There is no study on the consistency of angle β,VBE and VBE/FVC in evaluating the expiratory explosive force of school-aged children.In addition,the tangent of the MEFV curve partially overlaps with the curve itself,which reflects the change of forced expiratory flow(FEF)to some extent.Therefore,the study speculates that the angleβ may have a certain value in the evaluation of airway obstruction and it is expected to become a new index for the evaluation of airway obstruction.Fe NO is a simple and non-invasive biological indicator,which is an objective basis for the evaluation of airway inflammation(especially eosinophil inflammation).Previous study has shown that Fe NO can help to determine the diagnosis of asthma,but there are a few studies on the role of Fe NO in the diagnosis of asthma in school-aged children.The purpose of this study was to evaluate the consistency of angle β,VBE and VBE/FVC in expiratory explosive power in children,and to explore the value of angle β combined with Fe NO in the diagnosis and treatment of asthma in school-aged children.Objective1.To evaluate the consistency of angle β,VBE and VBE/FVC in expiratory explosive force of school-aged children and to explore the value of angle β in the quality control of lung function test in children;2.To explore the value of angle β combined with Fe NO in the diagnosis and treatment of asthma in school-aged children.Materials and methodsFrom January 2018 to August 2020,140 children(6 to 14 years old)diagnosed asthma for the first time in the Third Affiliated Hospital of Zhengzhou University,Luoyang Maternal and Child Health Hospital,Luohe second people’s Hospital were selected as asthma group.108 normal children in the same age group were selected as control group.In addition,the children in the acute attack of asthma were divided into mild group and moderate group according to the severity of the attack.After standardized treatment of asthma,some children were divided into three groups: initial treatment group,1-month treatment group and 3-month treatment group.The general conditions of the subjects(including sex,age,height and weight),FEV1%,FEV1/FVC%,FEF25%,FEF50%,FEF75%,VBE,VBE/FVC and Fe NO in each group were collected,and the angle β of each group were statistically analyzed.In this study,SPSS 25.0 and Graph Pad Prism8.0.1 software were used for data statistical analysis.Results1.Comparison of general condition and parameters between asthma group and control groupThere was no significant difference in sex,age,height and weight between the asthma group and the control group.The angle β,VBE and VBE/FVC in the asthma group were significantly lower than those in the control group(P < 0.001),and the pulmonary function parameters(FEV1%,FEV1/FVC%,FEF25%,FEF50%,FEF75%)in the asthma group were significantly lower than those in the control group(P < 0.001).The Fe NO value in the asthma group was significantly higher than that in the control group(P < 0.001).2.Comparison of parameters between mild group and moderate group in acute attack of asthmaThe angle β in the mild group was significantly higher than that in the moderate group(P < 0.001),but there was no significant difference in FEV1%,FEV1/FVC%,FEF25%,FEF50%,FEF75% and Fe NO between the mild group and the moderate group.3.Comparison of parameters in different treatment time groupsAfter standardized treatment,FEV1%,FEV1/FVC%,FEF25%,FEF50% and FEF75% increased gradually,while Fe NO decreased gradually(P < 0.05).Compared with the initial treatment group,the angle β was not significantly improved in the 1-month treatment group(P > 0.05),but increased significantly in the 3-month treatment group(P < 0.001).4.Consistency and correlation analysis of angle β,VBE and VBE/FVCThe angle β was negatively correlated with VBE and VBE/FVC(P < 0.001),but Kappa consistency test showed that the degree of consistency among them was weak.5.Comparison of diagnostic efficacy of parameters in asthmaArea under ROC curve of single index:FEV1/FVC%>angle β>FEF25%>FEF75%>FEF50%>Fe NO>FEV1%;Area under ROC curve of combined index:Angle β+FEV1/FVC%+Fe NO>angle β+FEV1/FVC%>angle β+FEF25%>angle β+FEF75%>angle β+FEF50%>angle β+Fe NO>angle β+FEV1%.Conclusions1.The consistency of angle β with VBE and VBE/FVC is weak.Therefore,angle β can’t be used as a substitute index of VBE and VBE/FVC to evaluate children’s expiratory explosive power.2.Angle β has a certain value in the diagnosis of asthma,and it combined with Fe NO and FEV1/FVC% can improve the accuracy of asthma diagnosis in school-aged children.In addition,angle β can be used to evaluate the severity of asthma.