Clinical, Functional And Inflammatory Markers In Assessing Exercise-Induced Bronchoconstriction In Asthmatic Children.

BACKGROUND Bronchial challenge with exercise helps monitoring of asthmatic children. The relationship between clinical scores, lung function and inflammatory markers with exercise-challenge outcomes remains controversial. AIMS To compare asthma scores (ACT), spirometry, blood eosinophil counts (%), fractional concentration of exhaled nitric oxide (FENO), exhaled breath temperature (EBT) and acidity of the exhaled breath condensate (EBCpH) with exercise-testing outcomes in asthmatic children. METHODS In 55 asthmatic children aged 10.3±2.9 yr, M/F 40/15, we assessed ACT, spirometry, blood eosinophil counts (%), FENO, EBT (tidal breathing), EBCpH, and skin prick test. Spirometry was repeated 1, 5, 10, 15 and 20 minutes after exercise as well as FENO (5, 20 min) and EBCpH (20 min). Exercise-induced bronchoconstriction (EIB) was defined as a FEV1 fall >10%. Bronchial response to inhaled salbutamol (“D” prefix) in FEV1 and FEF25-75 was assessed 20 min after exercise. Atopy was defined by the presence of at least one positive skin wheal to common allergens (≥3 mm). RESULTS In all children, the baseline FEF25-75% correlated with the post-exercise fall in FEV1 (r=0.31, p=0.02). The post-exercise FENO fall, DFEV1 and DFEF25-75 correlated with the post-exercise fall in both FEV1 and FEF25-75 (e.g. FENO fall with FEF25-75 fall, r=0.39, p=0.003). Blood eosinophil counts increased in relationship with the fall in FEV1, especially in atopic children (n=48; r=-0.39, p=0.009). ACT scores, EBT and EBCpH did not correlate with exercise-testing outcomes. The 27 patients with EIB had lower baseline FEF25-75%, increased FVC%, FENO fall, DFEV1, DFEF25-75 and blood eosinophil counts than the 28 patients without EIB [e.g. DFEV1: 26.7 ± 25.8 vs 6.5 ± 7.8, p=0.000; blood eosinophils (%): 7.7 ± 5.1 vs 5.0 ± 3.6, p=0.03]. CONCLUSION Baseline lung function, airway responsiveness to salbutamol and atopic-eosinophilic inflammation better assess EIB than clinical scores and markers of acidity or temperature of the exhaled breath. Our data support the hypothesis on specific rather than unspecific exercise-induced changes of the airways.