What is FeNO?
Fractional Exhaled Nitric Oxide (FeNO) is a test that measures the levels of nitric oxide in your child's airways.
A FeNO test is performed by blowing into a mouthpiece on the end of a handheld monitor.
Why is FeNO carried out?
It can help with a diagnosis of asthma.
A high level of nitric oxide when you breathe out can be a sign that you have inflamed airways, and could be a sign that you have asthma.
It is also useful in monitoring your asthma and medications by measuring the inflammation in your airways.
What do I have to do in the test?
You put your mouth around the end of the mouthpiece and blow into the machine for a few seconds until your doctor or nurse tells you to stop. You will be guided through what to do and how long to blow for.
How long does it take to do?
The test should only takes a few seconds.
Do I need to do anything before the test?
There are a few things to do to prepare for the test:
- Avoid vigorous exercise at least 1 hour before
- Avoid smoking at least 1 hour before
- Hot drinks, caffeine and alcohol should be avoided for at least 1 hour before
- Avoid nitrate rich foods, such as green leafy vegetables (celery, leek, beetroot, lettuce, cabbage, spinach) at least 3 hours before
You should continue to take all of your usual inhalers and medications before the test.