Changes in exhaled nitric oxide and breath pH during fluticasone wean in asthma

Background: Inhaled corticosteroid (ICS) therapy improves asthma outcome. Both the anti-inflammatory efficacy and toxicities of ICS therapy are dose dependent. Therefore, there is interest in monitoring airway inflammation during ICS dose adjustments. Objective: Fraction of expired nitric oxide (FENO) and exhaled breath condensate (EBC) pH were studied as noninvasive, corticosteroid-responsive markers of airway inflammation. Methods:We prospectively studied the effect of stepwise ICS wean on FENO and EBC pH over 6 months in otherwise healthy adults with moderate persistent asthma. Results:Eighteen subjects completed the initial dose titration and 13 completed the protocol. Of these, 7 weaned off ICS completely and 6 had exacerbations. FENO rose significantly with ICS withdrawal, though there was heterogeneity in the starting level and the degree of rise. EBC pH was collected at home in all subjects and fell more in subjects who had an exacerbation than in those who did not. The decrease in pH was associated with hazard of exacerbation. Conclusion: FENO can be a patient-specific index of airway inflammation during ICS dose titration; change in EBC pH is one home marker that might possibly be used during ICS dose titration. However, additional studies are required.