Acidity of the exhaled breath condensate in assessing bronchial challenge with exercise in children: Effect of deaeration

Background Acidity of the exhaled breath condensate (EBCpH) is being studied for asthma monitoring. Scarce data regards the usefulness of this marker in bronchial challenge with exercise, particularly of deaerated or non-deaerated EBCpH samples. Aims To measure EBCpH and the fractional concentration of exhaled nitric oxide (FE NO ) in paediatric patients investigated for exercise-induced bronchoconstriction (EIB). Methods In 130 children aged 5-17 yr (82 males) we measured EBCpH (before and after deaeration with Argon), FE NO , spirometry and skin prick test for common allergens. Spirometry was repeated 1, 5, 10, 15 and 20 minutes after exercise as well as FE NO (5, 20 min) and EBCpH (20 min). EIB was defined as a FEV 1 fall >10%. Results Baseline lung function but not EBCpH or FE NO correlated with the exercise-induced fall in FEV 1 (e.g. with FEV 1 % r=0.27, with FEF 25-75 % r=0.36, p NO levels, but not in EBCpH after exercise correlated with the post-exercise decrease at 5 and 20 min (r=0.37, p Lower non-deaerated EBCpH values were found in subjects with EIB (n=30) than in subjects without EIB (n=100) either at baseline and after exercise (7.17±0.48 vs 7.43±0.51 and 7.25±0.31 vs 7.47±0.47, p vs 8.18±0.21, p Conclusion Baseline non-deaerated EBCpH (by including volatile acids) probably reflect peripheral airway obstruction that promotes EIB. Exercise-released inflammatory mediators could enhance deaerated EBCpH in atopic subjects.