FeNO [Fractional Exhaled Nitric Oxide]

FeNO measurements are considered as a surrogate for eosinophilic airway inflammation and especially useful in patients with asthma who do not demonstrate spirometric abnormalities. FeNO levels in exhaled air are higher in asthmatics than in healthy subjects.

It decreases after anti-inflammatory treatment in asthma. It is useful in monitoring treatment in patients with asthma. It is useful in those patients who have overlap features of both asthma and COPD. Other situation wherein FeNO is being used are cystic fibrosis, Primary ciliary dyskinesia, certain interstitial lung diseases and occupational exposures etc. FeNO measurements are simple and is a biomarker in the assessment of inflammatory airways diseases.