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Measuring FeNO

Nurse FeNO testing female patient with NIOX VERO
FeNO predicts the likelihood of steroid responsiveness more consistently than spirometry, bronchodilator response, peak flow variation, or airway hyperresponsiveness to methacholine.1-3

Asthma is often misdiagnosed or under-diagnosed

Obtaining an accurate asthma diagnosis can be a challenge as many diseases present with symptoms similar to asthma.Traditional methods of asthma assessment only give part of the picture, as they are only indirectly associated with airway inflammation.5

In addition, conventional evaluation methods such as peak flow and spirometry only measure airflow and not airway inflammation. They are effort dependent and sometimes the results can be difficult to interpret.6 Likewise, symptom assessments are subjective and lack sensitivity.7

As a result, asthma is often misdiagnosed or under-diagnosed. Studies of adults diagnosed with asthma suggest that up to 30% do not have clear evidence of the condition. Some may have had asthma in the past, but it is likely that many will have had an incorrect diagnosis.8

FeNO adds a new dimension to traditional clinical tools

FeNO testing is non-invasive and has proven more reliable in predicting inflammation and steroid responsiveness than spirometry, bronchodilator response, peak expiratory flow, or airway hypersensitivity.9 It enhances the ability of the clinician to make better treatment decisions, avoiding empiric steroid trials and unnecessary long-term treatment.10,11

The American Thoracic Society (ATS) strongly recommends the use of FeNO measurement to aid in the assessment, management, and long-term monitoring of asthma.9 In their 2011 clinical practice guideline, the ATS emphasizes the importance of using FeNO to:

  • Understand possible causes of respiratory symptoms where there is no diagnosis of asthma
  • Ensure appropriate treatment with anti-inflammatory medications, especially inhaled corticosteroids
    • Patients with asthma caused by allergic/eosinophilic airway inflammation have high levels of FeNO that decrease with corticosteroid treatment
    • Knowing whether airway inflammation is present can help avoid an empiric trial of steroids
Read white papers and publications on NIOX VERO Review an overview of clinical guideline to interpretation of FeNO levels

References: 1. Knuffman JE, Sorkness CA, Lemanske RF Jr, et al; for the Childhood Asthma Research and Education Network of the National Heart, Lung, and Blood Institute. Phenotypic predictors of long-term response to inhaled corticosteroid and leukotriene modifier therapies in pediatric asthma. J Allergy Clin Immunol. 2009;123:411-416. 2. Szefler SJ, Martin RJ, King TS, et al; for the Asthma Clinical Research Network of the National Heart, Lung, and Blood Institute. Significant variability in response to inhaled corticosteroids for persistent asthma. J Allergy Clin Immunol. 2002;109:410-418. 3. Smith AD, Cowen JO, Brassett KP, et al. Exhaled nitric oxide: a predictor of steroid response. Am J Respir Crit Care Med.2005;172:453-459. 4. Morice AH, Fontana GA, Sovijarvi ARA, et al on behalf of the ERS Task Force. The diagnosis and management of chronic cough. Eur Respir J. 2004;24:481-492. 5. Dweik RA, Boggs PB, Erzurum SC, et al; on behalf of the American Thoracic Society Committee on Interpretation of Exhaled Nitric Oxide Levels (FeNO) for Clinical Applications. An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FeNO) for clinical applications. Am J Respir Crit Care Med. 2011;184:602-615. 6. National Asthma Education and Prevention Program; National Heart, Lung, and Blood Institute. Expert panel report 3: guidelines for the diagnosis and management of asthma. Full report 2007. http://www.nhlbi.nih.gov/guidelines/asthma/asthgdln.pdf. Published August 28, 2007. Accessed September 13, 2011. 7. Smith AD, Cowan JO, Filsell S, et al. Diagnosing asthma: comparisons between exhaled nitric oxide measurements and conventional tests. Am J Respir Crit Care Med. 2004;169:473-478. 8. Asthma: diagnosis and monitoring of asthma in adults, children and young people. National Guideline Centre. Commissioned by the National Institute for Health and Care Excellence. November 2017. 9. Dweik RA, Boggs PB, Erzurum SC, et al on behalf of the American Thoracic Society Committee on Interpretation of Exhaled Nitric Oxide Levels (FeNO) for Clinical Applications. An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FeNO) for clinical applications. Am J Respir Crit Care Med. 2011;184:602-615  10. LaForce C, Brooks E, Herje N, et al. Impact of exhaled nitric oxide measurements on treatment decisions in an asthma specialty clinic. Ann Allergy Asthma Immunol. 2014; 113: 619-623. 11. Hanania NA, Alpan, O, Hamilos, DL et al. Omalizumab in Severe Allergic Asthma Inadequately Controlled With Standard Therapy. Ann Intern Med. 2011;154:573-582.