What is spirometry?

A spirometry test measures the amount of air you are capable of exhaling during a forced breathing maneuver and the speed at which you can exhale it. The results from this test give an idea about the capacity of your lungs and the condition of your airways.

What should you expect?

The test is performed with a device called a spirometer that measures the amount and speed of the air you can blow out. Different methods of measurement lead to differently sized and shaped spirometers. A spirometer can be as small as a hair dryer, or it can be part of a large complicated device the size of a small desk, or it can be part of a glass booth that you sit inside. The test is performed the same way on all spirometers.

To begin:

  • You will be asked to sit upright in a chair.
  • You may be asked to loosen your bra or your belt if these could restrict your breathing.
  • If you are using supplemental oxygen then you will be asked to take your nasal cannula off.
  • You will probably have your nose clipped so that you will breathe only through your mouth.
  • You will be asked to breathe through a mouthpiece. It is important that you wrap your lips snugly around the mouthpiece in order to get a tight seal so that air does not leak.

When the spirometry test starts:

  • You will be told to breathe quietly for several breaths and then, when asked, to take as deep a breath as you possibly can and then to blow it out as fast and as long as you possibly can
  • The staff person giving you the test should be encouraging and coaching you the entire time you are performing the test
  • At the end of the test you may be asked to take another fast, deep breath in but this part is often optional.

You will probably need to perform the spirometry test at least three times but more may be necessary and this will be based on test quality and reproducibility. The staff person who is performing your test should tell you each time whether you did the test correctly, or if not, which part of the test you need to improve.

The spirometry test may make you very short of breath. This is normal. Despite this you need to blow out for at least six seconds, and to blow as hard as you can every time. If you become too tired, short of breath, or uncomfortable please take time to recover between tests. If you are using supplemental oxygen you can use it between tests if this will help you recover. You can drink water if your throat is uncomfortable or dry. Kleenex should be available if you start coughing.

The nose clip and the mouthpiece should both be new and clean at the start of your testing session. If you are having difficulty keeping your lips snugly around the mouthpiece you should be given a flanged rubber mouthpiece to use which should also be new and clean. The staff person performing your test should be wearing gloves or at a minimum should have performed hand hygiene before your testing session.