Airway nitrogen oxide measurements in asthma and other pediatric respiratory diseases.

Markers for airway inflammation that can be measured noninvasively in expired air may be helpful in treating patients with asthma. For example, levels of nitric oxide are high in the breath of children with asthma exacerbations and decrease with anti-inflammatory therapy. Expired nitric oxide testing has now been standardized and may be useful for children with recurring wheezing that is diagnostically or therapeutically challenging. However, the results may be influenced by several biochemical and anatomic variables and must therefore be interpreted with caution.