The official ATS Clinical Practice Guideline suggests that measurement of fractional nitric oxide (NO) concentration in exhaled breath (FENO) is a useful tool for assessing asthma during clinic visits (Am J Respir Crit Care Med, 2011). This review included 6 studies of patients with asthma utilising FeNO (2 in adults and 4 in children/adolescent) (last searches were in February 2009).
There was no significant difference in exacerbations between groups for FeNO compared with controls. The daily dose of inhaled corticosteroids at the end of the study was decreased in adults whose treatment was based on FeNO in comparison with the control group. However, children who had treatment adjusted according to FeNO had an increase in their mean daily dose of inhaled corticosteroids.
The authors concluded that tailoring of asthma treatment based on FeNO levels has not been shown to be effective in improving asthma outcomes in children and adults. They questioned thejustification to advocate the routine use of either sputum analysis (due to technical expertise required) or FeNO in everyday clinical practice.
Although conventional tests such as FEV1 are only indirectly associated with airway inflammation, they assess the functional capacity of asthmatic patients and provide actionable information during clinic visits.
A systematic review and meta-analysis: tailoring asthma treatment on eosinophilic markers (exhaled nitric oxide or sputum eosinophils). Thorax 2012;67:199-208 doi:10.1136/thx.2010.135574.
ATS Guideline on Exhaled Nitric Oxide Levels (FENO) Use
Image source: NioxMino.