Bronchial and alveolar nitric oxide in exercise-induced bronchoconstriction in asthmatic children

BACKGROUND: Epidemiological studies have shown an association between the severity of exercise-induced bronchoconstriction (EIB) and fractional exhaled nitric oxide at the flow of 50 mL/s (FeNO(50)). However, no study has assessedthe correlation between alveolar production (C(alv)) and bronchial flux (J(NO)) of nitric oxide (NO) and EIB in asthmatic children.OBJECTIVE: To identify the relationship between severity of EIB and bronchial or alveolar nitric oxide.METHODS: Our group included 36 allergic children with intermittent asthma. The EIB was determined by a standard exercise challenge and the severity was expressed as the maximum change in percentage from the baseline value of lungfunction (ΔFEV(1)%, ΔFEF(25-75)%) after exercising. A chemiluminescence analyser at multiple flows was used to calculate FeNO(50), J(NO) and C(alv,) which reflectlarge airways, J(NO) and alveolar concentration of NO respectively.RESULTS: Sixteen (44.4%) children presented a ∆FEV(1) ≥ 10%, eight (22.2%) had ∆FEV(1) ≥ 15% and nine (25%) children had a ∆FEF(25-75) ≥ 26%. A significant correlation was observed between severity of EIB and FeNO(50) , J(NO) and C(alv.)EIB was significantly more severe in children sensitive to indoor allergens compared with outdoor allergens only (P = 0.014); those children showed also higher levels of C(alv) (P = 0.003) and of J(NO) (P = 0.044).CONCLUSIONS AND CLINICAL RELEVANCE: Our results suggest that inflammation is present in the central and peripheral airways and that it is associated with the severity of EIB.