Fractional Exhaled Nitric Oxide Test

Participants generally found FeNO easier because its breathing technique was simpler and often produced a result with one effort. FeNO was considered easier than spirometry by nearly all interviewed participants. The FeNO test is not a general-purpose nitric oxide sufficiency screen; its clinical utility is specifically tied to airway inflammatory disease. FeNO is a single-breath biomarker of type 2 airway inflammation. Counterintuitively, higher exhaled NO signals a problem — NO that should be retained in the airways is being lost, indicating impaired recirculation and airway inflammation. FeNO device size and tube changes made use outside the home harder for most participants. The FeNO device used in the study was not specifically designed for home use. The FeNO test is primarily used for diagnosing and monitoring asthma because elevated airway NO indicates inflammation.