The Application Analysis Of Lung Function Combined With Exhaled Nitric Oxide In Chronic Cough Of Children

Chronic cough is one of the common reasons for children to go to the outpatient department of respiratory,and a diversified cause brings great difficulties to diagnosis and treatment.At present,it is difficult for children to complete multiple clinical examination items.Therefore,it is a hot issue in clinical research to find a effective way to examine children with chronic cough,aiming to effectively distinguish different etiologies of chronic cough,and it is also the key to clinical treatment.In recently years,follow-up lung function examination and the determination of exhaled nitric oxide（Fe NO）have gradually matured,their applications in children with chronic cough have gradually increased.However,the results of those mothods are still controversial due to different etiologies.In this study,statistical analysis was conducted on the distribution of pulmonary function combined with Fe NO in children with chronic cough,providing a new clinical idea for the diagnosis and etiology analysis of chronic cough.Objectives:By analyzing the changes of lung function and Fe NO in children with chronic cough,to determine the role of lung function and Fe NO in the etiological diagnosis of chronic cough in children.Methods:Collected 156 patients with chronic cough who were admitted to the Pediatrics Respiratory Department of the First Hospital of Jilin University,from January 2019 to July 2020,and collected all patients’information,including gender,age,height,weight and other basic information.According to the age for classificiation,<3 years old for tidal breathing lung function and Fe NO;3～5 years old for impulse oscillating lung function（IOS）and Fe NO;>5 years old completed the lung volume and ventilation function and Fe NO,all patients in this group also needed to complete the bronchial diastolic test.Recorded the indexes of 3 groups of patients and analysed the proportion of abnormal indexes in each group.In addition,the lung volume and ventilation function test group was divided into cough variant asthma（CVA）group and non-CVA group according to the medical history,clinical manifestations,cough onset characteristics and bronchial diastolic test,analysed the basic information,the results of the lung volume,ventilation function and Fe NO of two groups,and used the ROC curve to determine whether the differential results had diagnostic significance,and to calculate the best cut-off value,all operations were carried out in SPSS26.0 software.Result:1.A total of 156 cases of children with chronic cough were included in this study,including 99 cases of boys（63.46%）and 57 cases of girls（36.54%）.All age groups could be affected.Most of them were over 3 years old,especially early school age and school age children.2.The proportion of abnormal tidal breathing lung function was 71.43%in patients with chronic cough under 3 years old,and the proportion of abnormal Fe NO was 85.71%.The positive rate of the combined determination of the two was 100%.3.The percentage of abnormal IOS and Fe NO were 21.21%and 53.03%respectively in 3 to 5 years old children with chronic cough,and the positive rate of combined determination was 71.21%.4.The proportion of abnormal lung volume and ventilation function was 55.42%in children with chronic cough over 5 years old,and the proportion of abnormal Fe NO was 61.45%,and the positive rate of combined determination was 66.27%.5.The pulmonary function indexes FEV₁,FEV₁/FVC,FEF₅₀,FEF₇₅ and PEF in CVA group were 1.40±0.51,81.37±6.52,1.58±0.63,0.72±0.36 and 2.74±1.05,respectively,which were significantly lower than those in non-CVA group,and P<0.05;the result of Fe NO test in CVA group was 29.63±5.96,which was significantly higher than that in non-CVA group,and P<0.05.6.ROC curve analysis showed that FVC%,FEV₁%,FEV₁/FVC%,FEF₅₀,FEF₇₅and PEF were all having significant diagnostic value for CVA.And among them,FVC%,FEV₁%,FEF₅₀,FEF₇₅,Fe NO had higher value for the diagnosis of CVA.The areas under the curve were 0.757,0.784,0.729,0.720 and 0.746,and the maximum Youden index were 0.413,0.474,0.419,0.457,0.462,respectively.At that time,the best cut-off value were 85.25%,97.35%,1.815L/s,0.735L/s,27ppb,respectively.The sensitivity were 75.6%,55.6%,68.2%,77.3%,68.4%,and the specificity were65.8%,91.9%,73.7%,77.8%,respectively.Conclusion:1.Chronic cough in children is more common in early school age and school age children,and boys are more common than girls.2.The positive rate of lung function test combined with Fe NO test in the examination of chronic cough in children is better than that of each test separately.3.The indexes of FEV₁,FEV₁/FVC,FEF₇₅,FEF₅₀ and PEF in CVA are significantly lower than those in non-CVA,and the Fe NO is significantly higher than that in non-CVA children.4.FVC%,FEV₁%,FEF₅₀,FEF₇₅,Fe NO have diagnostic significance for CVA,and the sensitivity and specificity of diagnosis are the highest when 85.25%,97.35%,1.815L/s,0.735L/s,27ppb respectively is taken as the cut-off value.