Domiciliary diurnal variation of fractional exhaled nitric oxide (FeNO) to monitor asthma control

Background: A major goal of asthma management is achieving and maintaining optimal control. Current assessment is based on symptoms and lung function. Portable monitors for FeNO have now become available. Objectives: We evaluated whether domiciliary daily home FeNO monitoring could be useful as an index of asthma control. Methods: Fifty asthmatic subjects and 15 healthy volunteers with a range of asthma severity underwent asthma control questionnaire (ACQ), spirometry before and after salbutamol and sputum induction. FeNO and peak expiratory flow (PEF) were measured twice daily for 2 weeks. A record of exacerbations was obtained 3 months later. Results: Diurnal FeNO variation in uncontrolled asthmatics was significantly greater than in controlled asthmatics (p Conclusions: Diurnal variation in FeNO combined with ACQ scores can be used as a better marker of asthma control and as a predictor of the risk of future exacerbation. Prospective studies are warranted.