Exhaled breath biomarkers in asthmatic children.

Asthma is a chronic inflammatory disease of the airways which affects about 10-25% of children in Western countries. Monitoring of inflammation is considered an important tool in the diagnosis and follow-up of asthma, including assessment of severity and response to treatment. Bronchial biopsy specimens and bronchoalveolar lavage are reliable ways to assess airway inflammation. However, such invasive procedures are not feasible for repetitive measurements. In clinical practice, correlation of symptom scores and measurement of lung function with airway inflammation may be poor. Bronchial hyperresponsiveness to metacholine and induced sputum are time-consuming, difficult to perform before adolescence and can not be measured serially. Therefore, the greatest interest has recently been directed towards alternative approaches to determine markers involved in the inflammatory reaction. In childhood, such approaches must be non-invasive, reproducible and easy to perform. Furthermore, the inflammatory markers should accurately measure not only the degree of inflammation but also changes depending upon treatment or allergen exposure. Recently, the measurements of inflammatory markers in both exhaled breath and condensate have emerged as a possible non invasive method in the assessment of airway inflammation.