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Why FeNO works better with audio

Devices that measure FeNO have markedly influenced the clinical decision-making of healthcare professionals and helped alter treatment plans for patients with asthma.1 However, true accuracy and reproducibility of the results depend on various factors, including proper use of the FeNO testing device. How can you be sure a patient is correctly carrying out a test? One element that can really help is the quality of the audio guide that the FeNO measurement device provides.

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The amount of nitric oxide (NO) in exhaled air is increased in patients who have airway inflammation, one of the key characteristics of asthma, and major asthma guidelines recommend testing.2-8 Understanding the level of NO in a patient’s airways therefore provides valuable insight into what’s going on in the lungs and can help to reach a diagnosis of asthma so it’s important to be accurate.


Most FeNO measurement devices are designed to be user-friendly for both doctor and patient, providing reliable results without the need for invasive procedures.9-10 The simplicity and portability of these desktop machines also mean FeNO tests can be taken and analysed during a routine appointment.9

Importantly, making sure you choose a machine that includes audio guidance will ensure FeNO testing is accessible to as many patients as possible, including the visually impaired.


The American Thoracic Society (ATS) and the European Respiratory Society (ERS) published a joint guideline recommending that FeNO levels be tested using a sample of exhaled breath that has been expelled at a flow rate of 50ml/s.11 This is a precise speed that could be difficult to track but FeNO devices that provide audio and visual guides give real-time direction for patients to help them complete the test at the recommended rate.

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Here’s a quick rundown of how audio guides help you make the most of FeNO testing:

  1. Improve accuracy
  2. Achieving a reliable FeNO test result depends on the patient following the instructions. Audio guides play a significant role in helping patients maintain that all-important exhalation flow rate of 50ml/s. NIOX VERO® includes Flow Rate Control™, which plays a continuous sound during the exhalation phase to indicate when a patient is breathing into the device at a steady rate. If the breath becomes too forceful for an accurate measurement, the sound increases in pitch. If the exhalation rate drops, the sound becomes lower, helping patients keep their breath on track.

  3. Enhanced user experience
  4. Audio guides can help enhance the FeNO testing process by providing clear, concise and easy-to-understand instructions. Patients can use the audio guides to direct them through the testing process to ensure they achieve actionable results.

  5. Increased compliance
  6. Patients are more likely to comply with testing procedures when they understand what is expected of them. Audio guides can help patients get to grips with the testing process and understand the importance of maintaining the flow rate for accurate results.

  7. Saves time
  8. Audio guides can help streamline the testing process by providing clear instructions, reducing the time patients spend on the device.

    Audio guides are an invaluable part of non-invasive procedures like FeNO testing, helping to open up the process to as many patients as possible. They provide guidance and instruction to patients, helping them achieve independent success to improve FeNO test accuracy, increase compliance and save time. To see audio in action with FeNO by NIOX®, head to our video library and watch our video on performing a FeNO test.

    If you’re curious about the science behind the exhaled volume of 50ml/s in the ATS/ERS guidelines, you can read more about that here.

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Hanania NA et al. Measurement of fractional exhaled nitric oxide in real-world clinical practice alters asthma treatment decisions. Annals of Allergy, Asthma & Immunology. 2018 Apr 1;120(4):414-8.
2. 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.
3. Khatri SB et al. An official American Thoracic Society clinical practice guideline: use of fractional exhaled nitric oxide to guide the treatment of asthma. Am J Respir Crit Care Med. 2021;204(10):e97-e109.
4. 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.
5. Louis R et al. European Respiratory Society Guidelines for the Diagnosis of Asthma in Adults. Eur Respir J 2022; in press
6. National Institute for Health and Care Excellence (NICE). NICE guideline. Asthma: diagnosis, monitoring and chronic asthma management. 2021.
7. Expert Panel Working Group of the National Heart, Lung, and Blood Institute (NHLBI) administered and coordinated National Asthma Education and &Prevention Program Coordinating Committee (NAEPPCC) et al. 2020 Focused updates to the asthma management guidelines: a report from the National Asthma Education and Prevention Program Coordinating Committee Expert Panel Working Group. J Allergy Clin Immunol. 2020 Dec;146(6):1217-1270.
8. Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. 2021 update.
9. Alving K et al. Validation of a new portable exhaled nitric oxide analyzer, NIOX VERO®: randomized studies in asthma. Pulm Ther. 2017;3:207-218.
10. Pavord ID et al. The current and future role of biomarkers in type 2 cytokine‐mediated asthma management. Clinical & Experimental Allergy. 2017;47(2):148-60.
11. American Thoracic Society; European Respiratory Society. ATS/ERS recommendations for standardized procedures for the online and offline measurement of exhaled lower respiratory nitric oxide and nasal nitric oxide. Am J Respir Crit Care Med. 2005;171(8):912-30.