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

Summary: 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 (FeNO50). However, no study has assessed the correlation between alveolar production (Calv) and bronchial flux (JNO) 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 lung function (ΔFEV1%, ΔFEF25-75%) after exercising. A chemiluminescence analyser at multiple flows was used to calculate FeNO50, JNO and Calv, which reflect large airways, JNO and alveolar concentration of NO respectively. Results: Sixteen (44.4%) children presented a ΔFEV1 ≥ 10%, eight (22.2%) had ΔFEV1 ≥ 15% and nine (25%) children had a ΔFEF25-75 ≥ 26%. A significant correlation was observed between severity of EIB and FeNO50, JNO and Calv. 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 Calv (P = 0.003) and of JNO (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. Clinicaltrials.gov NCT00952835. © 2012 Blackwell Publishing Ltd