Exhaled nitric oxide measurements in asthma: Techniques and interpretation

The routine assessment of bronchial asthma includes the measurement of pulm onary function and bronchial hyperreactivity, both of which assess airways obstruction and smooth muscle contractility, The recent emphasis in the res earch and therapy of asthma has been on airway inflammation, however, This is probably because, to date, methods of directly examining lower airway ce lls and mediators are either invasive (bronchoscopy) or time consuming and expensive, for example, sputum induction. The analysis of exhaled mediators promises to provide a simple rapid and repeatable way of noninvasively ass essing airway inflammation in asthma and other inflammatory airways disease , Although there are numerous exhaled volatile and nonvolatile substances, exhaled nitric oxide measurement has excited the most interest, This chapte r concentrates on the methods available to measure exhaled nitric oxide in a standardized and repeatable manner and also discusses the potential role of exhaled nitric oxide in the management of asthma.