Measurement of Exhaled Nitric Oxide (NO) and Bronchial Provocation Test With Mannitol as a Predictor of Response to Inhaled Corticosteroids in Chronic Cough

Chronic cough is defined by its persistence beyond 8 weeks. Many conditions can explain the existence of a bronchial inflammation. In the management of chronic cough, the search for bronchial hyperreactivity (HRB) is recommended. The treatment relies primarily on the prescription of inhaled corticosteroids. It has been shown recently that the existence of an HRB with Methacholine (bronchial provocation test used in routine) does predict the effectiveness of inhaled corticosteroid treatment in no more than 50% of cases. It is now possible to assess the bronchial inflammation by rapid, non-invasive and reproducible tests such that the fraction of exhaled nitric oxide (FeNO) and bronchial provocation test with mannitol. In a retrospective study, it was shown that an increased value of FeNO (cut-off \> 35 ppb) predicts a positive response to treatment with a sensitivity of 90% and a specificity of 80%.