Expired breath hydrogen peroxide as a marker of acute airway inflammation in children with asthma

Airway inflammation is an important factor in the development and progression of asthma. Activation of inflammatory cells induces a respiratory burst resulting in the production of reactive oxygen species, such as hydrogen peroxide [H[2]O[2]]. The aim of this study was to measure the levels of H[2]O[2] in expired breath condensate in asthmatic children, compared with levels in age-matched controls and to outline its relation to asthmatic triggers, asthma severity, treatment modalities, pulmonary function tests, and total and differential white cell count. Forty asthmatic and 20 healthy children were studied. Their ages ranged from 6-18 years. Expired H[2]O[2] was measured using a colorimetric assay. In asthmatic children, there was a significant elevation of the mean H[2]O[2], level compared to values in controls [p=0.003]. Asthmatic triggers [e.g.: bad housing1 passive smoking, upper respiratory tract infection] showed non significant relation to the mean value of H[2]O[2] level in expired air of asthmatic children. Bad housing showed significant relation to number of acute asthmatic attacks [p=0.03]. There was no significant difference between moderate and severe asthma regarding H[2]O[2] levels [p=0.424] Similarly, there was no significant difference between asthmatic patients whether they received inhaled steroids or not regarding H[2]O[2] levels [p=0.875]. Basal spirometric pulmonary function tests, showed no significant correlation to the level of H[2]O[2]. Correlations of H[2]O[2] level in expired air of asthmatic children with total leukocytic counts [r=0.024; p=0.899], eosinophilic counts [r=0.092; p=0.630] and neutrophilic counts [r=0.021; p=0.910] were all non significant. We conclude that expired H[2]O[2] is significantly elevated in asthmatic patients. Measurement of expired H[2]O[2], may be useful to assess airway inflammation and oxidative stress in asthmatic patients