Spirometry and bronchodilator reversibility test

Spirometry is a breathing or lung function test. It measures:

• how much air you can breathe out in one forced breath
• the total amount of air you can breathe out of your lungs.

You may do a spirometry test at the GP surgery, or at a clinic or hospital outpatients department.

Spirometry is suitable for most adults, young people, and children over five.  

But it's not safe to have spirometry test if:

• you have other conditions including heart problems and uncontrolled blood pressure
• you have a chest infection
• you recently had a heart attack or stroke
• you've recently had some types of surgery.

Your GP or other healthcare professional will ask about your medical history and make sure it's safe for you to have a spirometry test.

A spirometry test can help explain what's causing symptoms like coughing or feeling short of breath.

It can diagnose and monitor lung conditions like asthma, COPD, and pulmonary fibrosis (scarring in the lungs).

A spirometry test is done using a small machine attached to a mouthpiece, called a spirometer.

The nurse or healthcare assistant can show you how to blow into the spirometer before starting the test.

To do the test, you need to:

• sit down next to the spirometer
• wear a soft clip on your nose. This is to make sure all the air from your lungs goes into the mouthpiece.
• take a deep breath to fill your lungs with air
• close your lips tightly around the mouthpiece
• breathe out as fast and hard as you can, for as long as you can, through the mouthpiece
• keep blowing out to get all the air out of your lungs.

You will need to put as much effort into the test as you can to get an accurate result. The healthcare professional will ask you to repeat the test a couple of times.

Some people can feel a bit dizzy or faint afterwards, but this usually lasts just a few minutes. If you do feel a bit faint or lightheaded afterwards, let the person performing the test know, to make sure you have time to recover.

Some people find that the test makes them cough.

If the spirometry test shows that your airways are narrowed, you may need to do a bronchodilator reversibility test.  

This is when you do a second spirometry test after taking bronchodilator medicine. It can show your healthcare professional how your airways respond to the bronchodilator medicine.

Bronchodilator medicines open your airways and make breathing easier.  It’s the bronchodilator medicine in your reliever inhaler that helps open your airways if you have an asthma attack or COPD flare up.  

A spirometry and BDR test can show if symptoms might be caused by asthma, (COPD), or Asthma-COPD overlap (ACO).  ACO is where people have features of both asthma and COPD.  

If your airways open well after taking bronchodilator medicine, it’s more likely that you have asthma rather than COPD.