Stay in tune with your allergic asthma patients


Fenom Pro™ Asthma Monitor

A finely-tuned instrument for guiding preventative treatment decisions

A rising FeNO level is an early sign of worsening eosinophilic inflammation. Orchestrate treatments with confidence by tracking your patients’ FeNO on every visit.


Bring clarity to asthma management

Take the guesswork out of corticosteroids. Monitoring detailed FeNO results now and over time helps pinpoint the most effective anti-inflammatory treatments and dosing levels.

FeNO testing helps measure airway inflammation severity

FeNO testing
Fenom Pro
Fenom Pro

Role of nitric oxide (NO) and FeNO in human health

In the late 1980s, scientists discovered that the human body has complex enzymes, called NO synthases, that synthesize nitric oxide (NO), a ubiquitous gas that diffuses and acts locally on cells to mediate physiologic responses.1 In the vasculature, the effect of NO on smooth muscle results in relaxation and vasodilation, while in the airway, NO results in bronchodilation.

NO binds to receptors on smooth muscle called soluble guanylate cyclase, thereby raising intracellular cyclic GMP, which inhibits the entry of calcium into the cell and relaxes the muscle. In 1998, the Nobel Prize in Physiology or Medicine was awarded to 3 researchers for their role in elucidating the mechanisms of action of NO.²

NO and inflammation

NO is an inflammatory mediator that is produced in large amounts during inflammatory conditions. A reactive species, NO increases oxidative stress when present in large amounts and results in vasodilation in areas of inflammation. In asthma, where there is inflammation of the airways with infiltration of inflammatory cells (e.g., eosinophils), inflammatory mediators, including NO, are produced.

Exhaled NO

NO was first identified in the breath of humans in 1991.3 NO, produced in the airway mucosa by NO synthases, diffuses into the airway lumen and is exhaled. Although all individuals exhale NO due to physiologic production, in those with asthma, FeNO levels are elevated due to allergic asthmatic inflammation (eg, infiltration of eosinophils).

The elevated FeNO levels in asthma and the reduction in FeNO levels that occurs after ICS treatment underpin the utility of FeNO testing in asthma and has led to its widespread application.