Chronic Obstructive Pulmonary Disease (COPD) | Spirometry

You may need to do a spirometry test if your doctor thinks you have chronic obstructive pulmonary disease (COPD).

Path to improved health

What is spirometry?

Spirometry is a type of “pulmonary function” test. It measures how well your lungs are working. Your doctor uses the test results to help determine whether you have COPD or other potential lung disease. If you have COPD, the results also show how severe your COPD is.

How does the test work?

During a spirometry test, a machine called a spirometer measures how much air you’re able to blow out of your lungs. People who have COPD aren’t able to blow out as much air as quickly as people who don’t have COPD.

How is the test performed?

To begin, your doctor may give you a nose clip to wear. It may be a bit uncomfortable but it will likely be soft. This helps make sure you’re breathing through your mouth. Then, you will put a plastic tube in your mouth. This tube is connected to the spirometer. You will then be asked to take a deep breath in, then blow all the air in your lungs into the tube as hard and fast as you can.

The spirometer will measure your airflow. Your doctor will look at the results. He or she may ask you to take the test more than once, or to take the test after you’ve taken an inhaled medicine.

Things to consider

What do the results mean?

The spirometry test will tell your doctor two things:

  • How much air you’re able to breathe out in 1 second. This is called “forced expiratory volume in 1 second” (FEV1).
  • How much air you’re able to breathe out in 1 breath. This is called “forced vital capacity” (FVC).

To determine how well your lungs are working, your doctor will divide your FEV1 by your FVC. This is called the FEV1/FVC ratio. If your FEV1/FVC is less than 70%, your lung function isn’t normal. This may mean you have COPD.

If your doctor has diagnosed you with COPD, he or she may ask you to have a spirometry test from time to time. This will help keep track of your lung function and determine if your COPD is getting worse.

Questions for your doctor

  • Do I need a spirometry test?
  • How long will the test take?
  • Do I need to do anything to prepare for the test?
  • Will it be hard to blow into the tube?