Affecting approximately 262 million people worldwide, asthma is a chronic condition of the lungs that causes airway inflammation.1
Typical symptoms include:
- Breathlessness
- Wheezing
- Coughing
- Chest tightness
When your airways become inflamed, breathing often becomes difficult. Recent research conducted by Asthma + Lung UK showed over 42,000 people ended up in emergency care in 2023/ 2024, having visited at least five times in the previous 12 months.2
These numbers evidence the critical need for better asthma management in the reduction of burdens upon healthcare systems.
The key to better management of asthma lies in the assessment of airway inflammation. Higher levels of nitric oxide (NO) gases are produced when someone’s airways become inflamed. FeNO (Fractional exhaled Nitric Oxide) tests are the simplest method for measuring a person’s NO levels.
What is FeNO testing?
A FeNO test with a device like the NObreath® is a quick, easy, non-invasive, and accurate way to measure NO levels in exhaled breath. NO is a marker of eosinophilic airway inflammation, common in allergic asthma. Patients follow on-screen instructions to inhale and then exhale into the device, providing instant results.
FeNO levels are measured in parts per billion (ppb). A high FeNO level indicates airway inflammation and can aid in diagnosing asthma.
ATS/ERS Clinical Guidelines Summary for Interpreting FeNO Levels3,4:
Image Credit: Bedfont® Scientific Ltd
Note: These reflect the ATS and ERS guidelines. FeNO interpretation thresholds may vary between guidelines.
FeNO testing with the NObreath®
The NObreath® is a FeNO device manufactured by Bedfont® Scientific Limited. Bedfont® has over 48 years of knowledge and expertise in designing and manufacturing medical breath analysis devices. The NObreath® has improved asthma management for over 15 years, providing healthcare professionals (HCPs) with a fairly priced solution for FeNO testing.
Suitable for both adults and children, the NObreath® is well-suited to primary and secondary care settings. For more information on the NObreath®, visit the website here.
Why is FeNO testing useful in asthma?
Airway inflammation cannot be directly observed; FeNO tests allow HCPs to track underlying inflammation and, when used alongside an extensive clinical history, can diagnose asthma.
Having access to a FeNO device is useful throughout the asthma pathway. Not only does it aid an asthma diagnosis, but it also helps to guide treatment decisions.
Carrying out FeNO tests in routine asthma reviews allows HCPs to:
- Tailor inhaled corticosteroid (ICS) therapy,
- Identify steroid responsiveness,
- Guide step-up or step-down treatment strategies.
A patient who consistently presents with a high FeNO level indicates possible poor adherence to ICS, and can alert carers to instigate conversations about medication use.
Image Credit: Bedfont® Scientific Ltd
FeNO testing is incorporated into worldwide guidelines. Joint guidelines by the National Institute for Health and Care Excellence (NICE), the British Thoracic Society (BTS), and the Scottish Intercollegiate Guidelines Network (SIGN) now recommend FeNO as a first-line test for asthma diagnosis.
Future of FeNO testing
The biggest challenge with FeNO testing is accessibility; unfortunately, some areas do not have access to a FeNO device. In a recent interview with Carol Stonham MBE, we discussed the issues around funding.
In some areas, the Integrated Care Board (ICB) will pay for it, but in others, it is down to the Primary Care Network (PCN). However, if the PCN does not deem it a priority, it comes down to the individual General Practice (GP) surgeries.
Looking back at the shocking statistics at the beginning of this blog, it is clear that better asthma management is needed. FeNO is a valuable tool in modern asthma management. It guides HCPs to understand the underlying airway inflammation in asthma, leading to better patient outcomes.
With the NICE/BTS/SIGN guidelines update, FeNO testing is recommended as a first-line test for asthma diagnosis and management in adults. This means access to FeNO needs to improve.
For more information on FeNO testing and its central role in asthma care in the joint NICE/BTS/SIGN guidelines, click here to read our article on the guideline updates and FeNO testing.
References
- World Health Organization (2024). Asthma. (online) World Health Organization. Available at: https://www.who.int/news-room/fact-sheets/detail/asthma.
- Asthma + Lung UK. (2025). Surge in repeat hospital visits for lung conditions. (online) Available at: https://www.asthmaandlung.org.uk/media/press-releases/surge-repeat-hospital-visits-lung-conditions.
- Louis, R., et al. (2022). European Respiratory Society Guidelines for the Diagnosis of Asthma in Adults. European Respiratory Journal, (online) 60(3). DOI: 10.1183/13993003.01585-2021. https://pubmed.ncbi.nlm.nih.gov/35169025/
- Dweik, R.A., et al. (2011). An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FENO) for clinical applications. American journal of respiratory and critical care medicine, (online) 184(5), pp.602–15. DOI: 10.1164/rccm.9120-11ST. https://pubmed.ncbi.nlm.nih.gov/21885636/
About Bedfont® Scientific Ltd
Bedfont® Scientific has specialised in the design and manufacture of exhaled breath and gas monitoring instruments since 1976.
For medical gas monitoring, their Medi-Gas Check medical pipeline testing range verifies not only the quantity but also the quality of gas administered to patients.
Bedfont's breath analysers include carbon monoxide (CO) monitors such as the Smokerlyzer®, used for smoking cessation, and the ToxCO®, used by emergency services, to diagnose CO poisoning.
The NObreath® FeNO monitor provides accurate analysis of airway inflammation for the control of asthma, and the Gastrolyzer® range aids in the detection of gastrointestinal disorders and food intolerances. Quick and non-invasive, breath analysis is the new blood test.
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