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FeNO stands for fractional exhaled nitric oxide and testing is a simple and non-invasive way to measure the amount of nitric oxide (NO) that is exhaled from the lungs.1
NO is a naturally occurring gas that is produced in the body and helps to control the normal function of cells, as well as regulating processes in the nervous and immune systems.2 It also plays a role in inflammatory disorders, such as asthma.3 Respiratory problems can occur when physical activity triggers airway inflammation, producing uncomfortable symptoms. When this happens, FeNO levels rise.4
FeNO testing involves breathing into a device that measures the amount of NO in the exhaled breath sample. The test is quick and the results are available within a couple of minutes.1,5 Patients can take a FeNO test at the point-of-care with a simple desktop device during a routine medical appointment or with healthcare professionals in a clinical environment.6
In sport, the ability to breathe efficiently is critical to performance. Athletes with respiratory issues, such as asthma, may experience breathing difficulties that can impact their ability to train and compete at their highest level.7 FeNO testing can be used to monitor respiratory health and identify potential issues before they become a problem.8 Athletes with asthma may experience symptoms such as wheezing, coughing, and shortness of breath during exercise.9 FeNO testing can help to identify airway inflammation, a common symptom of asthma, and guide treatment options.4
A study led by Panagiotou in 2020 examined the link between physical activity and asthma, saying the two had an important association that had been underappreciated.10 The researchers highlighted the benefits of exercise in asthma and noted that aerobic exercise decreased eosinophilic airway inflammation, bronchial remodelling, and subsequently reduced FeNO levels. They pointed out that some evidence suggests that exercise may not only reduce allergic airway inflammation as measured by FeNO, but may also reduce nasal inflammation as measured by eosinophilic cell count and induce sustainable improvements in allergic symptoms.10
FeNO testing can also be useful as an asthma management tool for athletes training at high altitudes. High-altitude training is a common strategy used to improve endurance and performance.10 FeNO testing can help to identify potential respiratory issues.11 The Panagiotou team reported findings that high-altitude training also led to better improvement in PEFR-variability, exercise capacity and airway inflammation as assessed by FeNO when compared to low-altitude training.10
The value of FeNO testing in the management of exercise-induced bronchoconstriction (EIB) in children has also been examined.
A 2005 study conducted by Buchvald et al reported on the ability of exhaled NO to predict EIB in children of this age.12 The team were testing a hypothesis that FeNO could be used for pre-screening asthmatic children to exclude those with good asthma control who were unlikely to experience EIB.12 The theory was that a positive result for the use of FeNO, a simple point-of-care test6, could reduce the burden of exercise testing and the associated large demand on healthcare resources. Stable outpatient asthmatic school children performed standard exercise challenge tests on a treadmill and measured their FeNO.12
They found that EIB could be excluded with a probability of 90% in asthmatic children whose FeNO level was <20 ppb without current inhaled corticosteroid (ICS) treatment and <12 ppb in those taking ICS. They also noted that EIB reflects disease control and may be present despite a lack of daily symptoms and a normal lung function. They concluded that measuring FeNO is a simple tool to increase time and resource efficiencies in the screening for EIB, optimising the capacity for exercise tests in paediatric asthma monitoring.12 Overall, FeNO testing has been found to be a valuable tool for patients both looking to maintain their respiratory health, predict exacerbations and increase the vigilance of EIB.11-13 By monitoring airway inflammation and identifying potential respiratory issues, healthcare professionals can help sports enthusiasts of all ages make informed decisions about their training and treatment options. To see how FeNO could fit into your asthma care routine, take a quick look around the resources on niox.com
Learn more about the gold standard FeNO device.
1. 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.
2. Role of Nitric Oxide in Biology. University of Reading. Accessed: April 2023. Available at; https://www.reading.ac.uk/nitricoxide/intro/no/index.htm
3. Ricciardolo FL. Multiple roles of nitric oxide in the airways. Thorax. 2003;58(2):175-82.
4. 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.
5. Smith AD et al. Use of exhaled nitric oxide measurements to guide treatment in chronic asthma. N Engl J Med. 2005;352(21):2163-73.
6. Busse WW et al. Baseline FeNO as a prognostic biomarker for subsequent severe asthma exacerbations in patients with uncontrolled, moderate-to-severe asthma receiving placebo in the LIBERTY ASTHMA QUEST study: a post-hoc analysis. Lancet Respir Med. 2021;9(10):1165-1173.
7. Types of Asthma. Asthma & Lung UK. Accessed : April 2023. Available at ; https://www.asthmaandlung.org.uk/conditions/asthma/types-asthma
8. Global Initiative for Asthma (GINA). Global strategy for asthma management and prevention. 2022 update. Accessed: April 2023. Available at; https://ginasthma.org/
9. Why exercise can be a trigger. Asthma & Lung UK. Accessed: April 2023. Available at; https://www.asthmaandlung.org.uk/conditions/asthma/asthma-triggers/when-exercise-triggers-your-asthma
10. Panagiotou M et al. Physical activity: a missing link in asthma care. Journal of clinical medicine. 2020;9(3):706.
11. 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):1110-1119.
12. Buchvald F et al. Exhaled nitric oxide predicts exercise-induced bronchoconstriction in asthmatic school children. Chest. 2005;128(4):1964-7.
13. Diaconu R et al. Electrochemical monitoring of bronchial inflammation in pediatric athletes: A prospective study. Experimental and Therapeutic Medicine. 2022;23(2):1-6.