While airway inflammation is a major underlying characteristic of asthma, there are few methods which directly measure this. Evaluating airway inflammation using sputum eosinophils or airway biopsy can be expensive, invasive, time-consuming, and is often not readily available. FeNO testing provides a fast and accurate method to support diagnosis and management of asthma.

The majority of patients with asthma have Type 2/eosinophilic driven airway inflammation.⁴ The associated higher levels of nitric oxide (NO) in their exhaled breath can be simply measured to support optimal management of the condition.⁵