Exhaled Nitric Oxide (FeNO)
Services
- All Services
- Home-Based Sleep Study
- Lung Function Test
- Respiratory Consultation
- Exhaled Nitric Oxide (FeNO)
- Spirometry
- Lung Volumes Test
- Sleep Consultation
Indications
Your doctor may suggest an exhaled nitric oxide test (FeNO test) if you have:
- Ongoing asthma-like symptoms (wheeze, cough, chest tightness, shortness of breath)
- Suspected allergic/eosinophilic asthma
- Asthma that’s hard to control or keeps flaring
- A need to check if inhaled corticosteroids are working or need adjusting
- The need to monitor airway inflammation over time
What is a FeNO Test?
An exhaled nitric oxide test (FeNO test) is a quick, painless breath test. It measures the level of nitric oxide in your breath to check for inflammation in your airways, which is common in allergic/eosinophilic asthma. This information helps your clinician confirm or support an asthma diagnosis and monitor how well preventer puffers (inhaled corticosteroids) are working, so your treatment can be adjusted as needed.
What Can I Expect? (about 15–20 minutes)
Setting up the home-based sleep study usually takes about 15-20 minutes. Here’s what will happen:
1. You’ll sit comfortably and breathe into a mouthpiece attached to a small FeNO device.
2. Take a gentle breath in, then exhale slowly and steadily for a few seconds while the device measures your breath.
3. If requested by your doctor, you may also do spirometry (a separate lung function test with a few stronger blows).
Are There Any Risks?
The exhaled nitric oxide test is safe and non-invasive. You might feel briefly light-headed from the breathing steps, but this passes quickly.
How Do I Prepare?
(This procedure will take up to 30 minutes)
To keep your FeNO result accurate, please:
- Avoid strenuous exercise for 1 hour beforehand
- Avoid smoking/vaping for at least 1 hour beforehand
- Avoid hot drinks, caffeine, and alcohol for 1 hour beforehand
- Try to avoid nitrate-rich foods (e.g., beetroot, spinach, lettuce, celery) for about 3 hours before your appointment
- Let us know if you’re unwell with a cold or flu, as it can affect results
- Take regular medications as directed unless your clinician has asked you to pause anything—please bring a list of what you’ve used that day.
Request an Appointment with Sleepscope.
Call us or submit a request form to make an online booking.
