Patient and doctor with Vivatmo

What is FeNO?

FeNO – an inflammatory marker in our breath

NO molecules
Schematic illustration of molecules in exhaled breath (blue = NO)

The abbreviation FeNO stands for fractional exhaled nitric oxide (NO).

  • NO develops during allergic inflammation in the respiratory tract.
  • The NO concentration can be measured in exhaled breath.
  • There is a proven relationship between the NO concentration in exhaled breath and the extent of airway inflammation – the higher the NO content, the more severe the inflammation!

Nitric oxide, or NO, is a colorless gas that is produced in different parts of the body, such as the blood vessels, the nervous system, and the lungs. As a bioactive molecule, NO can have a variety of effects. It plays an important role in the immune defense system and in various inflammatory processes.

NO produced in the respiratory tract is released into the atmosphere with exhaled breath. The NO concentration in the air is measured in “parts per billion” (ppb), i.e. a concentration of 10 ppb is equivalent to 10 nitric oxide molecules per billion air molecules.1

FeNO measurement

FeNO measurement

is an uncomplicated, standardized and safe method for detecting airway inflammation. To detect NO produced in the lower airways, the exhaled breath has to be fractionated. The measurement of fractional exhaled NO – known as FeNO – has been standardized for clinical application.

Quick and stress-free FeNO testing thus permits a reliable statement to be made about the degree of airway inflammation in asthmatics.

FeNO concentration is therefore an important parameter for determining the extent of airway inflammation in asthma. Since measurement is relatively easy to perform and does not stress the patients, it is increasingly used as an additional diagnostic and progression parameter.

Benefits of FeNO measurement

The many benefits of FeNO measurement in the doctor’s practice have already been demonstrated in numerous scientific studies:


Diagnosing allergic asthma

FeNO measurement makes it possible to precisely determine the extent of airway inflammation. The FeNO result is obtained using a simple breath test.


Only as much medicine as you actually need

FeNO measurement helps you to optimally adjust your therapy to your current state of health in consultation with your doctor, ensuring you only take as much medicine as you actually need.


Better overview of disease progression

FeNO measurement allows you to monitor the extent of respiratory inflammation. This can help to reduce acute asthma episodes. 2,3 A worsening of the inflammation is indicated by increased FeNO values, allowing your doctor to adjust your therapy at an early stage.4

Order online

You can easily order your Vivatmo me, the world’s first FeNO measuring device for home use, and the bespoke disposable mouthpieces here.

1 Informationsblatt der Deutschen Atemwegsliga e.V. FeNO-Messung
2 Petsky et al. Cochrane Database of Systematic Reviews 2016;9:CD011440
3 Essat et al. Eur Respir J 2016;47:751-68
4 Bodini A et al. Chest 2017;132:1520-25