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How FeNO fits into the asthma routine for primary and secondary care

What if someone told you it was possible to start reducing asthma exacerbations by up to 50% using a simple desktop device, right there at the patient’s appointment? With FeNO (fractional exhaled nitric oxide) testing, you can.1 To get an idea of how it works in the real world, we spoke to consultant chest physician and the clinical director of respiratory medicine for NHS South-East England, Dr Richard Russell, to ask how he uses FeNO in his daily practice.2

Dr Russell told us his experience goes back to the development of FeNO testing when he first became aware of its potential. Since then, the technology has evolved from a lab-based machine into a desktop device that all healthcare professionals can have at their fingertips – and this is exactly where we find FeNO at Dr Russell’s appointments today.

FeNO testing in action

Dr Russell describes how he fits FeNO into his asthma care routine, using it in several ways. Firstly, elevated FeNO levels enhance the clinician’s ability to diagnose asthma and testing is used alongside other tests to rule asthma in and out. “More importantly,” Dr Russell adds, “high levels of FeNO are very predictive of response to inhaled corticosteroids (ICS).” If a patient presents with typical asthma symptoms such as cough, wheeze and breathlessness, and they have high FeNO, Dr Russell says it’s likely they have asthma.2

FeNO testing changed the treatment pathway for Dr Russell’s primary care patients. “It’s absolutely critical now in helping make a diagnosis of steroid-responsive asthma. Spirometry results may or may not be normal with asthma but high FeNO levels mean airway inflammation, which is key because asthma is an inflammatory condition.”2

FeNO testing is used extensively by Dr Russell and his colleagues in the secondary care setting too. Here, clinicians use FeNO values to check adherence. Asthma patients need to take controller medication regularly as prescribed. Unfortunately, Dr Russell says adherence is variable, describing it as “patchy at best”. However, if a patient’s FeNO is high, usually they start taking ICS and their FeNO comes down. If FeNO starts to rise again, it’s a clear sign that either the patient’s disease has worsened or they’re non-adherent. In this way, regular FeNO monitoring enables physicians to make an informed clinical judgement.2

FeNO for patient education

It's not only clinicians who benefit from the increased certainty that FeNO brings. FeNO values are also important for patients, helping them understand that they should respond well to their treatment. Involving patients in tracking their FeNO score with their healthcare team also means they plainly see how their medication helps. “Patients really love FeNO testing,” says Dr Russell. “They really want to know their number.”2

For example, if a patient has symptoms and they have “a FeNO value of 80 or 90, which is fairly typical of an early diagnosis of asthma, you treat them and the number comes right down. They get really excited about seeing that change. Because guess what! They’re feeling better too, so things line up”. Dr Russell finds that, at follow-up appointments, patients are eager to test their FeNO and know that playing their part in managing their condition is worth it.2

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FeNO the asthma risk estimator

Using FeNO as an asthma risk estimator, even in patients with mild or no symptoms, makes it a very useful addition in asthma management. Crucially, Dr Russell explains that symptoms and inflammation do not always appear together. The patient might not be experiencing the discomfort of asthma but could have high FeNO. This tells clinicians “there’s a fire in the lungs” and it needs to be treated because at some point, the disease could become out of control and any number of every-day triggers may well cause a potentially fatal exacerbation. In contrast, when patients are experiencing symptoms but their FeNO is low, then it’s time to look at what else might be wrong.2

Implementation in practice

From a practical point-of-view, FeNO testing is straightforward to carry out and, with results available in a couple of minutes, it’s of real value at the point-of-care and an integral part of the consultation. Testing FeNO first is a great starting point and, to save valuable appointment time, Dr Russell points out that clinicians can continue with the check-up while the FeNO device analyses the breath sample.2

Dr Russell performs FeNO testing at every consultation. For any clinician also considering implementing FeNO testing into their asthma diagnosis and management pathway, it’s an opportunity to establish a structured review of asthma. This might include FeNO, symptom scores, peak flow, spirometry and blood testing. A patient-centric approach may also include history, triggers, markers of allergy and adherence. “FeNO is part of a structured approach and we know that a structured approach to asthma improves outcomes,” Dr Russell says.2

You can listen to the full conversation with Dr Russell as he talks through his use of FeNO testing here.

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1. Petsky HL et al. Tailoring asthma treatment on eosinophilic markers (exhaled nitric oxide or sputum eosinophils): a systematic review and meta-analysis. Thorax. 2018;73(12):1110-9.
2. A conversation with Dr Richard Russell around the benefits of FeNO testing, 2022. ©NIOX®