The full form of FENO is fractional exhaled nitric oxide. FENO is a quick, simple, non-invasive, and safe method of determining airways inflammation that provides a complementary tool to other ways of assessing Asthma or any other airways disease. It measures the nitric oxide gas in an exhaled sample of a patient’s breath. The doctor will ask you to breathe slowly and steadily into a mouthpiece attached to a machine to measure the amount of nitric oxide in your breath. A higher level of nitric oxide in your breath may be a sign of Asthma. Nitric Oxide is found in the air and is higher in air polluted areas. It is also produced in our body if there is any inflammation.

What are the advantages of the FENO test?

Airways of patients suffering from breathing problems may inflame. The FENO test is used as a non-invasive biomarker of airway inflammation to help differentiate allergic and non-allergic asthma as well as between asthma and some other respiratory diseases. It also helps a doctor check if the medication a patient is taking is working. The diagnosis of Asthma is based on medical history, physical examination, and some tests like Spirometry or peak flow test but if the diagnosis is still uncertain then the clinicians may advise you to go for a FENO test.

Nitric oxide is produced in our body including lungs naturally to combat inflammation and relax the tight muscles. High levels of nitric oxide in a patient’s breath can mean that the airways are inflamed which is also a sign of Asthma.  Many Asthma organizations recommend FENO test to improve overall asthma diagnosis and management.

Disadvantages of FENO include:

  • The equipment is expensive
  • This test is highly flow dependent. Sometimes the flow is not controlled and requires multiple attempts to complete the test.

Precautions before going for the test:

You may be advised to avoid the following for better and accurate results at least an hour before the FENO test for better and accurate result: -

  • Caffeine
  • Smoking
  • Alcohol
  • Foods rich in nitrates, such as beetroot and green leafy vegetables.

How is the FENO test/ procedure performed?

The patient is asked to put a mouthpiece in the mouth that is attached to an electronic measurement device and asked to breathe in slowly and deeply until the lungs are filled with air. The doctor/technician then asks to exhale slowly and steadily so that the air flows out at an even rate and steadily. While this procedure is going on, the doctor/technician keeps an eye on an electronic device to check how much you are breathing out so that you can maintain a steady and even exhalation. You may have to repeat the test twice or thrice to get a better result. The test generally takes 5- 10 minutes to complete.

How to identify the problem through the test?

If the level of exhaled nitric oxide is higher than the normal range, means your airways are inflamed and could be a sign of asthma. The value of exhaled nitric acid is more than 40 parts per billion (ppb) for adults and more than 25 parts per billion (ppb) for children and adolescents is considered elevated. The normal range of FENO test is less than 25 ppb for adults and less than 20 ppb for children. The result of FENO test for Asthma may vary from person to person and your doctor may consider some other medical conditions while interpreting the test result like your asthma signs and symptoms, previous FENO or spirometry test, ongoing medication, age, and your lifestyle.

If you are looking for the FENO test get one, and don’t worry, the test is quick, safe, and painless. Our pulmonologists are trained in managing nearly every pulmonary condition and disease. Aakash Healthcare offers multidisciplinary treatment including bronchoscopy for patients who have asthma, COPD, sleep disorders, lung cancer, pneumonia, tuberculosis, and many other chest infections/diseases. Aakash Healthcare is considered one of the best hospitals/centres for chest diseases in Dwarka, Delhi, and has one of the best doctors for Asthma/chest diseases. The cost of FENO test is very less compared to other centres in Delhi even though the quality offered is same and meets the global standard.

with Dr. Akshay Budhraja


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