Exhaled nitric oxide measurements: clinical application and interpretation
Posted Jan 05 2010 11:12pm
The use of exhaled nitric oxide measurements (F Eno ) in clinical practice is now coming of age. There are a number of theoretical and practical factors which have brought this about. Firstly, F Eno is a good surrogate marker for eosinophilic airway inflammation. High F Eno levels may be used to distinguish eosinophilic from non-eosinophilic pathologies. This information complements conventional pulmonary function testing in the assessment of patients with non-specific respiratory symptoms. Secondly, eosinophilic airway inflammation is steroid responsive. There are now sufficient data to justify the claim that F Eno measurements may be used successfully to identify and monitor steroid response as well as steroid requirements in the diagnosis and management of airways disease. F Eno measurements are also helpful in identifying patients who do/do not require ongoing treatment with inhaled steroids. Thirdly, portable nitric oxide analysers are now available, making routine testing a practical possibility. However, a number of issues still need to be resolved, including the diagnostic role of F Eno in preschool children and the use of reference values versus individual F Eno profiles in managing patients with difficult or severe asthma.