Use of exhaled nitric oxide in the diagnosis and monitoring of childhood asthma: myth or maxim?

Abstract

Asthma is a common condition in children. This review describes the evidence from the literature and international asthma guidelines for using fractional exhaled nitric oxide (FENO) in the diagnosis and monitoring of childhood asthma. The accuracy ofFENOmeasuring devices could be further improved, the difference inFENOresults between devices are equivalent to what is considered a clinically important difference. For diagnosing asthma no guideline currently recommendsFENOis used as the first test, but many recommendFENOas part of a series of tests. A cut-off of 35 ppb is widely recommended as being supportive of an asthma diagnosis, but evidence from children at risk of asthma suggests that a lower threshold of 25 ppb may be more appropriate. Nine randomised clinical trials including 1885 children have addedFENOto usual asthma care and find that exacerbations are reduced when care is guided byFENO(OR for exacerbation compared to usual care 0.77, 95% CI 0.62–0.94). What is not clear is what cut-off(s) ofFENOshould be used to trigger a change in treatment. After 30 years of intensive research there is not sufficient evidence to recommendFENOfor routine diagnosing and monitoring asthma in children.Educational aimsTo give the reader an overview of literature that supports and does not support the role ofFENOin diagnosing asthma in children.To give the reader an overview of literature that supports and does not support the role ofFENOin monitoring asthma in children.To give the reader an understanding of the role ofFENOin international guidelines for diagnosing and monitoring asthma in children.