Exhaled nitric oxide in pediatric asthma.

Exhaled nitric oxide can now be measured in a clinical setting as a noninvasive, reproducible, facile, point-of-service test to measure airway inflammation, a central component of asthma that had not been assessed previously. An excellent surrogate marker of steroid-responsive eosinophilic airway inflammation, it serves to identify steroid-sensitive asthmatic patients and enables clinical monitoring of the response to steroid therapy and titration of the dose. Standardization of methodology and technological advances, such as the recent availability of handheld analyzers, individualized patient cards to store serial test measurements, and the assignment of coding procedural terminology, make this a necessary adjunct to clinical and functional assessment of airway obstruction and hyperresponsiveness in ambulatory pediatric and adult asthma practices.