Exhaled Nitric Oxide in Children Under 4 Years of Age With Recurrent Bronchitis

BackgroundThe objective of the study was to assess bronchial inflammation in preschool children with recurrent bronchitis by measuring exhaled nitric oxide.Patients and MethodsThe study included patients under 4 years of age with at least 3 episodes of wheezing in the past year (n=63) and a control group (n=30). Exhaled nitric oxide was measured in samples collected offline during spontaneous tidal breathing with a face mask and stored in Mylar balloons.ResultsThe fractional exhaled nitric oxide concentration (FE_NO) was higher in the group with bronchitis (mean [SD], 5.3 [1.3] parts per billion [ppb]) than in the control group (4.6 [1.1] ppb) (P=.02). There was a significant difference between the control group and children in the bronchitis group not treated with inhaled corticosteroids (P<.05), but not between controls and corticosteroid-treated patients. A relationship with eosinophil count was observed in that those with higher counts (>400 mL) had higher FE_NO levels (P<.01). No relationship was observed between FE_NO and a positive methacholine challenge test. Follow-up lasted at least 20 months. The initial FE_NO level did not differ significantly according to whether patients were subsequently transient, infrequent, or frequent wheezers (5.2 [0.98] ppb, 5.6 [1.5] ppb, and 4.8 [1.34] ppb, respectively; P=.36).ConclusionsIn children under 4 years of age with recurrent wheezing bronchitis who were asymptomatic at study entry, a small increase in FE_NO was observed although there was a good deal of overlap with the control group.