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More accurate diagnosis with FeNO testing

Airway inflammation must be assessed

Asthma is usually diagnosed by clinical history and symptoms, using spirometry and peak flow records to evaluate airway obstruction. However, the results of these tests may be inconclusive as patients can have normal airflow, especially in mild cases.1 Therefore, normal lung function cannot exclude asthma.2

Airway inflammation is a key characteristic of asthma but it is not currently routinely measured. As a result, the condition is frequently underestimated in 50% of patients. This is even more common in patients with high inflammation, 2/3 of whom may not be identified.3

Misdiagnosis is common

Over-diagnosis is increasingly common and occurs in around 33% of adults and 50% of children.4,5 Mistaken diagnoses mean unnecessary medication and avoidable strain on the healthcare budget. On the other hand, it is believed that up to half of asthma cases are not diagnosed, adversely affecting the patient's quality of life, causing long-term airway remodelling, a risk of exacerbations and even death.6,7

The risk of misdiagnosis is high in asthma and diseases that present with similar symptoms must be reliably ruled out. These may include chronic obstructive pulmonary disease (COPD), rhinosinusitis, bronchiectasis, as well as non-pulmonary causes such as gastroesophageal reflux disease (GERD), anxiety or cardiac disease.8

Introducing FeNO testing

FeNO is the most convenient biomarker of airway inflammation. In a single breath, right at the point-of-care, FeNO testing gives healthcare professionals a clear picture of the level of inflammation in a patient's lungs.

FeNO testing is strongly recommended in national and international guidelines to help diagnose airway inflammation and asthma.8,9

Asthma is
when FeNO >40 ppb10

FeNO testing makes a difference

FeNO testing helps healthcare professionals be more confident with their asthma diagnosis. Introducing FeNO testing is an effective way to start your newly diagnosed asthma patients on the right track to asthma control.

Identify patients likely to respond to ICS

FeNO is sensitive to inhaled corticosteroids (ICS): high FeNO levels indicate the patient is likely to respond. This can help titrate the first ICS prescription.
In contrast, it is unlikely that ICS will help control asthma in patients whose FeNO is low.8 Around 15% of asthmatics, typically middle-aged, overweight women, will not respond to ICS as expected.1,11

Help patients help themselves

FeNO testing is praised by many healthcare professionals as a great educational tool. Seeing their FeNO value helps patients understand the degree of airway inflammation in their lungs and the associated risks. Watching their FeNO come down to a healthier level is encouraging and may help patients with compliance to ICS medication.

Save time with FeNO

FeNO testing is a safe procedure that can easily be included in your clinical routine. It takes less than two minutes to perform a FeNO test and see the results at the point-of-care. FeNO advocate Dr Richard Russell (UK) describes it as a "desktop test", with the device available within arm's reach.


Learn more about the gold standard FeNO testing device.

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Join the thousands of healthcare professionals who have already performed over 40 million FeNO tests with NIOX®, and improve patient outcomes.


1. Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. 2021 update. 2. Gaillard EA et al. European Respiratory Society clinical practice guidelines for the diagnosis of asthma in children aged 5-16 years. Eur Respir J. 2021;58(5):2004173. 3. Hanania NA et al. Measurement of fractional exhaled nitric oxide in real-world clinical practice alters asthma treatment decisions. Ann Allergy Asthma Immunol. 2018;120(4):414-418. 4. Aaron SD et al. Reevaluation of diagnosis in adults with physician-diagnosed asthma. JAMA. 2017;317(3):269-279. 5. Looijmang-van den Akker I et al. Overdiagnosis of asthma in children in primary care: a retrospective analysis. Br J Gen Pract. 2016;66(644): e152-e157. 6. Nolte H et al. Unawareness and undertreatment of asthma and allergic rhinitis in a general population. Respir Med. 2006;100(2):354–362. 7. Kavanagh J et al. Over- and under-diagnosis in asthma. Breathe (Sheff). 2019;15(1):e20-e27. 8. Dweik RA et al. An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FeNO) for clinical applications. Am J Respir Crit Care Med. 2011;184(5):602-15. 9. National Institute for Health and Care Excellence (NICE). NICE guideline. Asthma: diagnosis, monitoring and chronic asthma management. 2021. 10 Wang Z et al. Agency for Healthcare Research and Quality (AHRQ). The clinical utility of fractional exhaled nitric oxide (FeNO) in asthma management. Comparative Effectiveness Reviews, 197. 2017. 11. Heaney LG et al. Eosinophilic and noneosinophilic asthma: an expert consensus framework to characterize phenotypes in a global real-life severe asthma cohort. Chest. 2021;160(3):814-830.