Exhaled nitric oxide (FE,NO) may provide an alternative noninvasive marker of inflammation in asthma that is convenient, quick, and inexpensive. NO, produced by the conversion of arginine via nitric oxide synthase (NOS), is elevated in human lungs in a variety of inflammatory diseases. Exhaled NO is increased in steroid-naive asthmatic subjects and during an asthma exacerbation, although it returns to baseline levels with appropriate anti-inflammatory treatment, and such measurements have been proposed as a simple non-invasive method of measuring airway inflammation in asthma.
Exhaled nitric oxide can be measured in various different parts of the respiratory tract from the nose to the distal respiratory tract via a bronchoscopic approach, or in patients who are intubated or tracheotomized. Exhaled nitric oxide is generally measured via chemiluminescence, using the reaction of ozone to generate light, which can be measured photometrically.sensitive NO analysers are now commercially available .
Exhaled nitric oxide has been proposed as a sensitive marker of airway inflammation, a simple and non-invasive measurement that may predict the efficacy of anti-inflammatory treatment in asthma.Despite its apparent promise in this regard, there are few studies currently available that have addressed this issue, and those that have been performed have generally studied mild asthmatics whose response to therapy is usually not a problem.