Exhaled nitric oxide in children under 4 years of age with recurrent bronchitis

Abstract Background The objective of the study was to assess bronchial inflammation in preschool children with recurrent bronchitis by measuring exhaled nitric oxide. Patients and Methods The 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. Results The 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 400 mL) had higher FE NO levels ( P 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). Conclusions In 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.