Fractionated breath condensate sampling: H2O2 concentrations of the alveolar fraction may be related to asthma control in children

Background: Asthma is a chronic inflammatory disease of the airways but recent studies have shown that alveoli are also subject to pathophysiological changes. This study was undertaken to compare hydrogen peroxide (H2O2) concentrations in different parts of the lung using a new technique of fractioned breath condensate sampling. Methods: In 52 children (9-17 years, 32 asthmatic patients, 20 controls) measurements of exhaled nitric oxide (FENO), lung function, H2O2 in exhaled breath condensate (EBC) and the asthma control test (ACT) were performed. Exhaled breath condensate was collected in two different fractions, representing mainly either the airways or the alveoli. H2O2 was analysed in the airway and alveolar fractions and compared to clinical parameters. Results: The exhaled H2O2 concentration was significantly higher in the airway fraction than in the alveolar fraction comparing each single pair (p = 0.003, 0.032 and 0.040 for the whole study group, the asthmatic group and the control group, respectively). Asthma control, measured by the asthma control test (ACT), correlated significantly with the H2O2 concentrations in the alveolar fraction (r = 0.606, p = 0.004) but not with those in the airway fraction in the group of children above 12 years. FENO values and lung function parameters did not correlate to the H2O2 concentrations of each fraction. Conclusion: The new technique of fractionated H2O2 measurement may differentiate H2O2 concentrations in different parts of the lung in asthmatic and control children. H2O2 concentrations of the alveolar fraction may be related to the asthma control test in children.