Clinical value of fractional exhaled nitric oxide level in predicting bronchial hyperreactivity in asthmatic children

Abstract

Objective To evaluate the clinical value of fractional exhaled nitric oxide (FeNO) level in asthmatic children to predict bronchial hyperresponsiveness by analyzing the correlation between fraction of exhaled nitric oxide and bronchial provocation test. Methods One hundred and fourteen asthma outpatients of Shengjing Hospital were enrolled, FeNO levels, spirometry and bronchial provocation test were measured. Results In the bronchial provocation test, there were 33 positive and 81 negative cases.The positive group had a significantly higher FeNO levels than the negative ones(19.0×10-9 vs.16.0×10-9, P=0.000). By the ROC curve, the best FeNO cut-off value to predict bronchial hyperresponsiveness was 38.5×10-9 with high specificity(92.6%) but relatively low sensitivity(36.4%). There was no relationship between methacholine provocative dose causing a 20% fall in FEV1(PD20-FEV1) and the level of FeNO. Conclusion FeNO level has important predicting value for bronchial hyperreactivity in children with asthma.The level of FeNO >38.5×10-9 has high predictive value in asthmatic children with bronchial hyperreactivity. Key words: Exhaled nitric oxide; Methacholine bronchial provocation test; Asthma; Children