The way to diagnose and manage asthma has changed with FeNO testing.

NICE guidelines and FeNO

The NICE Guideline NG245 Asthma: diagnosis, monitoring and chronic asthma management, published on 27 November 2024, provides a clear and evidence based framework for assessing and managing asthma in both adults and children. A key feature of the guideline is the use of FeNO testing, a simple and non invasive way to measure Fractional exhaled Nitric Oxide as an indicator of eosinophilic airway inflammation.

FeNO testing measures the level of nitric oxide in exhaled breath and offers valuable insight into inflammation that is common in eosinophilic asthma. It works alongside other diagnostic tools such as spirometry and bronchodilator reversibility testing, forming an important part of the NICE asthma diagnostic pathway.

Key NICE Recommendations for FeNO Testing

Adults aged 16 and over

A FeNO level of fifty parts per billion or more suggests significant eosinophilic airway inflammation and supports an asthma diagnosis when combined with clinical history.

Children aged 5 to 16

A FeNO level of thirty five parts per billion or more supports a diagnosis of asthma when airway inflammation is suspected.

Integration with Other Objective Tests

NICE recommends using FeNO testing together with spirometry, bronchodilator reversibility and other objective measures where appropriate. When FeNO or blood eosinophils are raised, this can be enough to support an asthma diagnosis without the need for further lung function testing.

Monitoring and Ongoing Management

Variations in FeNO levels can help clinicians monitor asthma control and assess how well a patient is responding to inhaled corticosteroids. This makes FeNO a useful tool for guiding treatment decisions in both primary care and respiratory clinics across the UK.

QOF

The Quality and Outcomes Framework (QOF) now includes FeNO testing as a key element of high quality asthma care. This aligns with the NICE NG245 guideline which places strong emphasis on objective testing to improve diagnostic accuracy and support effective treatment decisions in both adults and children.

Key QOF Indicators for FeNO Testing

Use of FeNO to support diagnosis

Practices are encouraged to use FeNO testing to help confirm asthma in adults and children when airway inflammation is suspected.

Combining FeNO with other objective tests

FeNO results should be interpreted alongside spirometry findings and clinical assessments to provide a complete and reliable picture of the patient’s respiratory health.

Monitoring FeNO over time

Tracking changes in FeNO levels helps assess response to inhaled corticosteroids and can guide adjustments in treatment plans.

These indicators aim to reduce misdiagnosis, support personalised asthma management and promote consistent evidence based practice across primary care and respiratory services in the UK.

Why the change?

Asthma is a complex respiratory condition with symptoms that can overlap with other diseases such as chronic obstructive pulmonary disease (COPD) and chronic cough. Relying on subjective assessments or using spirometry alone can lead to uncertainty in diagnosis and delays in starting the right treatment. The updated NICE NG245 guideline helps address these challenges by giving greater priority to FeNO testing as an objective way to assess airway inflammation.

Key Reasons for the Change

Improved diagnostic accuracy

FeNO testing measures eosinophilic inflammation directly, which is a recognised feature of many asthma cases. Clear FeNO levels help clinicians distinguish asthma from conditions that do not involve eosinophilic airway inflammation, supporting more confident and timely diagnosis.

Better informed treatment decisions

FeNO testing also plays a role in guiding inhaled corticosteroid therapy. Raised FeNO levels suggest ongoing inflammation and may indicate the need to start or adjust ICS treatment. Monitoring FeNO over time helps clinicians assess whether treatment plans are effective.

Optimised patient outcomes

By using FeNO as part of the asthma diagnostic pathway, healthcare professionals can provide more accurate treatment earlier, reduce the risk of exacerbations and improve overall quality of life for patients. The inclusion of FeNO in NICE NG245 supports a clear and reliable framework for timely asthma care across the UK.

Asthma can be difficult to assess because there is no single objective test that can confirm the condition, and there is currently no recognised gold standard for diagnosis. Traditionally, clinicians have relied heavily on a detailed clinical history and patterns of symptoms. Research shows that as many as thirty per cent of adults given an asthma diagnosis do not have clear objective evidence to support it, while other studies indicate that asthma can also be underdiagnosed in some patients.

Evidence in people with severe asthma highlights the scale of another challenge. At least thirty per cent of patients are partly or completely non adherent with their prescribed medication, and poor adherence has been linked to thirty eight per cent of asthma related deaths. This shows how important accurate diagnosis and ongoing assessment are for effective asthma management.

The introduction of FeNO testing provides clinicians with an objective way to assess eosinophilic airway inflammation. By adding FeNO to the diagnostic process, healthcare professionals can make more informed decisions for patients with suspected asthma and ensure treatment is tailored to individual needs.

Diagnostic algorithms

The NICE NG245 guideline provides a clear diagnostic algorithm designed to support accurate and consistent asthma diagnosis. This approach combines FeNO testing with clinical assessment and other objective measures to help confirm or rule out asthma in both adults and children.

NICE Diagnostic Algorithm for Asthma

Initial clinical assessment

Clinicians begin by recording symptoms such as wheezing, breathlessness, chest tightness and cough. It is also important to identify potential triggers including allergens, exercise or occupational exposures.

Objective testing

FeNO testing

For adults, a FeNO level of fifty parts per billion or more indicates eosinophilic airway inflammation.
For children aged five to sixteen, a FeNO reading of thirty five parts per billion or more supports suspicion of eosinophilic asthma.
A FeNO level below these thresholds does not rule out asthma and may require further objective tests.

Spirometry

Spirometry assesses airflow obstruction. A low FEV1 to FVC ratio can support an asthma diagnosis when combined with clinical history.

Bronchodilator reversibility

BDR testing assesses how much lung function improves after using a bronchodilator and helps determine whether airflow obstruction is reversible.

Integrated diagnosis

NICE recommends combining FeNO results with spirometry, BDR findings and clinical history to confirm or exclude asthma. If results are unclear, clinicians should repeat FeNO and spirometry or consider other objective tests.

Reassessment and monitoring

FeNO variability over time can guide adjustments to treatment and support long term asthma control. This structured approach ensures patients receive accurate diagnosis and appropriate management within primary care and respiratory services across the UK.

FeNO in Asthma Management

FeNO testing has become a central part of modern asthma management. It provides clear insight into airway inflammation and supports personalised treatment decisions for both adults and children. Using FeNO in routine reviews helps clinicians optimise therapy, reduce exacerbations and improve long term outcomes.

How FeNO Supports Asthma Management

Guiding inhaled corticosteroid therapy
Raised FeNO levels suggest ongoing eosinophilic inflammation and may indicate the need to increase corticosteroid doses. Low or stable FeNO levels can show that inflammation is under control and that current treatment is effective.

Monitoring disease progression
Regular FeNO testing allows clinicians to track inflammation and identify early signs of worsening control. This helps reduce the risk of asthma attacks and supports timely adjustments to treatment.

FeNO in occupational asthma
FeNO testing can help identify airway inflammation caused by workplace exposures. This provides useful evidence when assessing suspected occupational asthma and supports decisions about mitigation and management.

FeNO variability over time
Tracking FeNO trends shows how airway inflammation changes between appointments. This helps clinicians take a proactive approach to treatment rather than waiting for symptoms to worsen.

By integrating FeNO testing into asthma monitoring, healthcare providers can deliver more accurate assessments and ensure patients receive the most effective and personalised care.

Download NICE guidelines

Access the full NICE NG245 guideline on Asthma: diagnosis, monitoring and chronic asthma management to stay up to date with best practice for assessing and treating asthma. The guideline provides clear, evidence based recommendations for incorporating FeNO testing into everyday clinical workflows and supports accurate diagnosis and effective long term management in both primary care and respiratory services across the UK.

NObreath® FeNO testing device to diagnose and monitor asthma

The NObreath® FeNO testing device, developed by Bedfont®, is a state of the art monitor designed to support accurate asthma diagnosis and management in line with the NICE NG245 guideline. This innovative and widely used tool provides reliable and non invasive FeNO measurements, making it an essential resource for clinicians across primary care and respiratory services.

Why Choose NObreath®

High precision
NObreath® delivers accurate FeNO readings that help identify eosinophilic airway inflammation, supporting confident asthma diagnosis and informed treatment decisions. The device has been evaluated against the chemiluminescence method, which is recognised as the gold standard for FeNO measurement.
(reference chemiluminescence evaluation document)

User friendly design
Compact, portable and simple to operate, the device is suitable for GP surgeries, community diagnostic centres, diagnostic hubs, asthma clinics and busy acute care settings.

Cost effective
NObreath® helps reduce unnecessary treatments and supports improved long term outcomes while aligning with QOF requirements for asthma care. A low cost annual rental option is available at six hundred and ninety five pounds including servicing. Dedicated primary care equipment offers are also available to support easier financial access to FeNO testing. Consumable costs are lower compared with other FeNO testing systems. The monitor and sensor are covered by a five year warranty.

Real time results
The device provides immediate FeNO levels, allowing clinicians to make quick and informed decisions during asthma reviews and diagnostic appointments.

Enhanced monitoring
NObreath® enables clinicians to track FeNO variability over time to assess the effectiveness of inhaled corticosteroids and make timely adjustments to asthma management plans.

Unique Features of the NObreath® FeNO Monitor

Fully compliant with FeNO recommendations within the NICE NG245 asthma guideline

Supports personalised treatment by measuring FeNO levels in suspected asthma, allergic asthma and occupational asthma

Designed for primary care with a focus on accuracy, usability and long term value

References

We have used facts and figures from NICE and other reputable sources to compile the content on this web page about the NICE guidelines. These are referenced in the bibliography below.

NICE BTS SIGN Guideline NG245: Asthma: diagnosis, monitoring, and chronic asthma management https://www.nice.org.uk/guidance/ng245/resources/asthma-diagnosis-monitoring-and-chronic-asthma-management-bts-nice-sign-pdf-66143958279109

NICE QOF Indicators: Objective testing in asthma https://www.nice.org.uk/indicators/ind272-asthma-objective-tests/chapter/indicator

NICE Asthma guidance resources <b</bhttps://www.nice.org.uk/guidance/ng245/resources
Bedfont® NObreath® FeNO FeNo testing device: NObreath product details, user manual and technical specifications https://resources.bedfont.com/nobreath-resources/

Chemiluminescence validation study 2011 – Kapande et al. – Comparative Repeatability of Two Handheld Fractional Exhaled Nitric Oxide Monitors