Spirometry

Spirometry is used to measure the amount of air you can inhale and exhale and the speed at which you can do so. It's a simple test, it's not painful and usually takes 15 to 30 minutes.

• You will be asked to blow into a tube that's attached to a device called a spirometer.
• A clip may be placed on your nose to make sure that no air escapes from it during the test.
• First, you breathe in fully and then seal your lips around the mouthpiece of the spirometer.
• You then blow out as fast and as far as you can until your lungs are completely empty.
• You will also be asked to breathe in fully and then breathe out slowly as far as you can.
• You will need to repeat this test a few times to ensure the measurements are accurate and consistent.
• You will be given time to recover between tests. You may feel a bit puffed or lightheaded afterwards. If this doesn't pass quickly, let the staff know.

Some people may be given an inhaled medication that relaxes and opens the airways (called a bronchodilator). Spirometry is then repeated after 15 minutes to test for any improvement in lung function.

Video: Performing spirometry in primary care

The video below shows how a spirometry test is done. It may take a few moments to load.

(National Asthma Council, Australia, 2010)

You should receive specific instructions from the doctor, nurse, or hospital department that does this test. Always follow these carefully.

If you are on any inhalers, take these along with you to your appointment. Wear loose comfortable clothing to the test so that you can take a deep breath. It's a good idea to go to the toilet right before the test, so you are comfortable.

You may be asked to avoid things that can affect your breathing before the test. 

• You may be given information on which inhalers to withhold and for how long before the spirometry test.
• Avoid drinking alcohol or drinks containing caffeine and avoid smoking a few hours before the test.
• Avoid eating a large meal or doing strenuous exercise.

Spirometry is quite a safe test, but blowing out hard can increase the pressure in your chest, tummy (abdomen or puku) and eyes. You may be advised not to have spirometry if you have:

• unstable angina or have had a recent heart attack or stroke
• had a recent pneumothorax (collapsed lung)
• had a recent operation on your eye, head or abdominal surgery or a burst ear drum.

Also let the staff know if you have a cold, the flu, nausea, diarrhoea or vomiting or if you've recently coughed up blood and you don't know why.

Your doctor will discuss the results of your test with you. The results will show whether you have a problem with your lungs by comparing your measurements with someone of the same age, sex and size. The results can also help determine what type of lung problem you have.

Both tests assess breathing and lung function but spirometry is different from a peak flow meter test.

The peak flow test measures how fast you can breathe out after you’ve taken a full breath in. Keeping track of your peak flow can show you when your symptoms are getting worse and when you need to use your reliever inhaler. Read more about peak flow meters.

Spirometry measures the amount of air you can breathe out from your lungs and how fast you can blow it out. Spirometry can help to assess whether your breathing is affected by narrowed or inflamed airways. The results are useful for diagnosing lung conditions and can sometimes be used to find out how severe your condition is.