Yes to NO: the first studies on exhaled nitric oxide-driven asthma treatment

Abstract

Recently, the first long-term studies examining the use of fractional exhaled nitric oxide (FeNO) to titrate steroid treatment in asthma were published 1, 2. Treatment decisions in asthma have always been made on the basis of symptoms, with or without taking peak flow into account. It is well established that, within an asthma population, both symptoms and airway obstruction correlate poorly with the presence and severity of airway inflammation. A strategy where inflammometry identifies the patient with airway inflammation would potentially prevent over treatment and allow for titration towards the lowest effective dose of steroids. It may also alert for under treatment or noncompliance. The validity of the concept of inflammometry-driven asthma management was supported by two earlier studies, both showing an important reduction in asthma exacerbations as a result of treatment strategies aimed at the reduction of bronchial hyperresponsiveness or sputum eosinophilia, both proxies for airway inflammation in asthma 3, 4. These studies have had limited practical impact due to the invasive and time-consuming nature of both hyperresponsiveness testing and sputum induction, and because the hyperresponsiveness-driven strategy led to an increased dose of inhaled steroids. The present introduction of FeNO measurements in clinical practise has been preceded by well over 1,000 published studies on FeNO in the past 15 yrs. These have established the genetic and molecular basis of nitric oxide (NO) generation and metabolism in the airways, the physiological and pathophysiological importance of NO in several respiratory diseases, and a number of confounding factors. FeNO can be measured within seconds with minimal discomfort and no risk to the patient. Routine methodology can be used in children from the age of ≥4–5 yrs. The results are highly reproducible and immediately available, and the test can be repeated easily and as often as needed. The American Thoracic Society …