Why Fractional Exhaled Nitric Oxide (FeNO)?

Fractional exhaled nitric oxide (Feno) is the only currently available point-of-care test of type 2 inflammation in asthma, being mediated by IL-13.¹ Clinical outcomes in asthma are closely related to type 2 inflammation, such as symptom control, lung function, airway hyperresponsiveness and exacerbations.²

The benefits of FeNO include improved accuracy of diagnosis for patients suspected of having asthma and it also helps both patients and clinicians understand the individual’s condition in more detail.³ Monitoring FeNO helps clinicians to differentiate between eosinophilic and non-eosinophilic exacerbations.⁴ FeNO can also signify the presence of other conditions which may requirement treatment due to the level of type 2 inflammation present in the lungs.⁵

Respiratory Consultant Dr Rory Chan outlines what FeNO is and the link between FeNO, exacerbation rates and lung function decline. He also presents on the cost-effectiveness of FeNO suppression testing and how FeNO fits into asthma guidelines.

Please also consider watching the on-demand video ‘FeNO Testing in Primary Care’ by Senior Respiratory Specialist Nurse Lead Sonia Silk. Sonia presents on the application of FeNO in the asthma pathway and practical tips for clinicians when conducting FeNO with patients.

References

1. Lipworth B, Kuo CR, Chan R. 2020 Updated Asthma Guidelines: Clinical utility of fractional exhaled nitric oxide (Feno) in asthma management. J Allergy Clin Immunol. 2020;146(6):1281-1282. doi:10.1016/j.jaci.2020.03.006

2. Howell I, Howell A, Pavord ID. Type 2 inflammation and biological therapies in asthma: Targeted medicine taking flight. J Exp Med. 2023 Jul 3;220(7):e20221212. doi: 10.1084/jem.20221212. Epub 2023 Jun 2. PMID: 37265457; PMCID: PMC10239209.

3. NHS England. Fractional Exhaled Nitric Oxide (FeNO). https://www.england.nhs.uk/aac/what-we-do/innovation-for-healthcare-inequalities-programme/rapid-uptake-products/fractional-exhaled-nitric-oxide/

4. McDowell PJ, Diver S, Yang F, et al. The inflammatory profile of exacerbations in patients with severe refractory eosinophilic asthma receiving mepolizumab (the MEX study): a prospective observational study. Lancet Respir Med. 2021;9(10):1174-1184. doi:10.1016/S2213-2600(21)00004-7

5. Chan R, Lipworth B. Impact of nasal polyps on endotype and phenotype in patients with moderate to severe asthma. Ann Allergy Asthma Immunol. 2021;127(5):548-552. doi:10.1016/j.anai.2021.06.007

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• Dr Rory Chan MBChB PhD

  Consultant Respiratory Physician and Senior Clinical Lecturer

  Read biography
  Dr Rory Chan MBChB PhD

  Consultant Respiratory Physician and Senior Clinical Lecturer NHS Tayside and University of Dundee

  Role and Location
  Consultant Respiratory Physician and Senior Clinical Lecturer at NHS Tayside and University of Dundee.

  Research Interest
  His specialist area of research relates to precision medicine in severe asthma.

  Memberships
  He is also an Editorial Board Member at the journal CHEST.