Abstract • 86

Expired NO levels are increased in asthmatics and are thought to reflect the degree of airway inflammation. We studied 32 steroid-naive stable atopic asthmatic children (11.8±2.3 yrs old) and 22 age-matched healthy controls to investigate whether baseline lung function or airway hyperresponsiveness are related to NO levels in exhaled air. Airway responsiveness was assessed as the dose of methacholine causing a 20% decrease in FEV1 from control (MCh Pd20) and NO levels were measured by chemiluminescence analysis of exhaled air. At baseline, asthmatic children had significantly higher NO levels than controls (Mean±SD: 30.0±19.2 ppb v.s. 4.0±2.4 ppb, respectively; p=0.0001) but there were no significant differences in lung function parameters [FVC, FEV1(%pred) and FEF25-75%]. Within the asthmatic group, exhaled NO levels were not significantly correlated with baseline lung function values or MCh Pd20 (p>0.09, each correlation). These results suggest that atopic children with mild-intermittent asthma, airway hyperresponsiveness to MCh Pd20 and NO levels in exhaled air are two independent markers of disease.

This abstract was funded by Ricerca Corrente from Ministero della Sanità, Rome, Italy, and a grant from Valeas S.p.A., Milan, Italy, to D.S.