Feno

What is FeNo?

FeNO devices are a novel medical technology used to aid in the diagnosis of asthma. FeNO devices measure fractional exhaled nitric oxide in the breath of patients. Nitric oxide is a biomarker for asthma which provides an indication of the level of inflammation in the lungs. FeNO testing produces a FeNO score which gives a value to the level of inflammation and can therefore be used to aid in the diagnosis of asthma. Although FeNO is primarily a diagnostic tool, it has an additional use in the ongoing monitoring of chronic asthma.

arrow_left_alt Back to Respiratory Physiology

Fractional Exhaled Nitric Oxide (FeNO)

Fractional exhaled nitric oxide (FeNO) is a quick, non-invasive NHS test used to measure lung inflammation, specifically assisting in diagnosing asthma and monitoring treatment effectiveness. It involves exhaling into a portable device, with high levels indicating eosinophilic airway inflammation. It helps reduce diagnostic errors and guides medication, such as inhaled corticosteroids.

FeNO is completely benign and universally applicable.

Rare light-headedness from controlled exhalation.

  • You inhale to total lung capacity through a mouthpiece.
  • You exhale slowly and steadily for ~10 seconds into the device.
  • The analyser measures nitric oxide concentration in parts per billion (ppb).
  • The test takes 1–2 minutes and may be repeated for accuracy.

FeNO can be influenced by factors like inhaled steroid use, recent infections, smoking/vaping, and allergen exposure, so your clinician will interpret the number with these in mind.

How to use our services

You can be seen through the NHS or as a private patient. You’ll need a referral first, and we’ll check it to make sure this service is right for you.

NHS Referral Going Private

Feedback

We want to hear about your experience with us. Whether it’s a compliment, suggestion, or concern, your voice helps us improve and provide better care.
Have you say today!