Spirometry (Lung Function Test)

To help work out a diagnosis of asthma your doctor needs to put the pieces of the jigsaw together.

One of the pieces needed is a lung function test.

There are a few tests we can do, including FeNOPeak Flow and Spirometry.

What is Spirometry?

Spirometry is a simple test used to help diagnose and monitor certain lung conditions, such as asthma. It measures how much air you can breathe out in one forced breath.

It's carried out using a device called a spirometer. This is a small machine attached by a cable to a mouthpiece.

Spirometry may be performed by a nurse or doctor at your GP surgery. It may be carried out during a short visit to a hospital or clinic.

Why is Spirometry carried out?

Spirometry can be used to help diagnose asthma if you have symptoms, or if your doctor feels you're at an increased risk of developing a particular lung condition.

It is also used to help monitor asthma and see how you are responding to medications and inhalers.

What do I have to do in the test?

You will be asked to blow into a mouthpiece with a clip on your nose. There are different types of blowing you will need to do, such as fast blows or long blows. This will be shown and explained to you when you attend.

You may have to repeat the test after taking your blue reliever inhaler. Your doctor or nurse will decide if this is needed.

How long does it take?

It can usually take anything from 30 to 45 minutes to complete. Some younger children may find they need a few attempts at this before they can do it. The doctor or nurse will go through this with them.

Do I need to do anything before the test?

There are a few things to do to prepare for the test.

Try to avoid:

  • Eating a large meal 2 hours before
  • Vigorous exercise 30 minutes before
  • Wearing tight clothing that may restrict breathing
  • Drinking alcohol 4 hours before
  • Smoking at least 24 hours before

It is necessary to stop some medications before the test.

Spirometry table.png

If you or your child do need to use your short acting bronchodilator (reliever) inhaler please tell your doctor or nurse when you arrive. They will need to know which inhaler, how many puffs, and at what time it was taken.

All other medications, including inhaled steroids and oral steroids should continue to be taken as directed by your doctor or nurse.