Spirometry and FeNO Assessments

Spirometry assessment

Spirometry is a pulmonary function assessment to help diagnose and monitor certain lung conditions. Spirometry measures the amount of air you can breathe out from your lungs and how fast you can blow it out. Spirometry can identify if your breathing is affected by narrowed or inflamed airways. The results are useful in diagnosing lung conditions such as COPD and asthma.

What does a spirometry assessment involve?

You’ll be asked to sit comfortably and may have a clip put on your nose to make sure all the air goes into the mouthpiece. You will be shown how to blow into the spirometer before starting.

You’ll be asked to take a deep breath and blow out as fast as you can into a mouthpiece, until your lungs are empty. You may be asked to blow 3 or more times into the spirometer, to check the readings are similar each time.

A spirometry assessment typically takes 10 to 20 minutes.

The person carrying out the test won't usually be able to give you your results immediately. The results will need to be looked at by a specialist respiratory consultant first and will then be discussed with you a few days later.

How should I prepare for a spirometry assessment?

You should stop taking bronchodilator medication before the assessment. Smoking before the spirometry assessment can affect the result, so avoid smoking beforehand.

On the day of your spirometry assessment, it’s a good idea to wear loose, comfortable clothing.

If you use inhalers, you should bring them to your appointment.

Fractional exhaled nitric oxide (FeNO) assessment

A fractional exhaled nitric oxide (FeNO) assessment is used to evaluate how much nitric oxide is in your breath, which provides an indication of the level of inflammation in the airways. If you have a breathing condition, your airways may be inflamed, and as such, the FeNO assessment can be used to support the diagnosis of asthma or other respiratory disease.

What does a FeNO assessment involve?

You will be asked to breathe into a plastic mouthpiece or a cardboard tube attached to a monitor. The monitor shows the reading on the screen.

You will breathe in deeply, with your mouth open, and then breathe out little by little until your lungs are empty. The breath out will normally take 10 seconds in adults (6 seconds in children). Some devices will make a sound to help keep the flow at the right level throughout the assessment. You may have to do the same measurement up to 3 times.

The results will be in parts per billion (ppb) of nitric oxide in your breath. More than 40ppb of nitric oxide indicates that your airways are inflamed, and it’s likely that you have asthma. Your assessor will also check your symptoms, such as cough, wheeze and shortness of breath while you perform the assessment. 

A FeNO assessment typically takes 5 to 10 minutes.

How should I prepare for a FeNO assessment?

You should stop taking bronchodilator medication before the assessment. Smoking before the FeNO assessment can affect the result, so avoid smoking beforehand.

Nitrate rich food, such as green leafy vegetables and beetroot, caffeine and alcohol can also affect the result, so do not eat or drink these for an hour before the assessment.

If you use inhalers, you should bring them to your appointment