Abstract: Objective: To examine the levels of fractional exhaled nitric oxide(FeNO) in children with cough variant asthma(CVA) and explore its value in the diagnosis and treatment of children with CVA.Methods: From June 2014 to June 2015,174 cases of children with chronic cough identified in the Second People′s Hospital of Changshu were involved in the study.There were 106 cases of CVA and 68 cases of non-CVA.The levels of FeNO and total serum IgE were detected in two groups.Evaluate the diagnostic value of FeNO to CVA by drawing ROC curve,and analyze the best cutoff value of CVA.Follow-up and FeNO test were made after treatment of 4 weeks.Results: The levels of FeNO for CVA group was (28.16±10.89) μg/L,significantly higher than the non-CVA group (17.91±5.48) μg/L,the difference being statistically significant(P<0.01).The area under the ROC curve was 0.775,and the optimal FeNO cutoff value was 20.5 μg/L with a sensitivity of 74.5% and a specificity of 84.5%.FeNO was positively related to total serum IgE in CVA children(r=0.285,P=0.003).After four weeks of treatment,the value of FeNO［(14.57±5.23)μg/L］ after treatment was significantly lower than that before treatment［(28.16±10.89)μg/L］,the difference being statistically significant(P<0.01).Conclusion: FeNO test has a high sensitivity and specificity in the diagnosis of CVA.Children with CVA have a close connection with allergic factors.Furthermore,if the FeNO level of CVA children has increased,the therapy of ICS will be effected.

Key words: Cough variant asthma, Chronic cough, Fractional exhaled nitric oxide, Children