Cardiopulmonary Exercise Test (CPET)

This test is often done to find out what is causing shortness of breath. During the test, you will walk on a treadmill. Or you'll ride on a stationary bike. The medical staff will measure how much oxygen and carbon dioxide your body uses. The test may show exactly where your breathing problems begin. They may begin in your lungs, your heart, or both. Your test results can also show a safe activity level for you. This test is usually done at a hospital or healthcare provider's office.

Before the test

Give yourself at least 30 minutes to check in. Get ready for the test as directed. You may be told to do any of these:

  • Follow any directions you are given for not eating, drinking, or smoking before the test. If you have diabetes, ask what you may eat or drink before the test.

  • Tell your provider about all the medicines you take. This includes prescription and over-the-counter medicines. It also includes vitamins, herbs, and other supplements. You may need to stop taking certain medicines before the test. Ask your provider if there are any medicines you can keep taking. This may include medicine to help your breathing.

  • Tell your provider if you have any upper respiratory conditions. These include a cold, sinusitis, bronchitis, or pneumonia.

  • Don't exercise the morning before the test.

  • Wear comfortable exercise clothing and walking shoes, such as tennis shoes.

  • Wear your dentures, if you have them. 

During the test

Small pads (electrodes) placed on your upper body will check your heart rate. A device (pulse oximeter) will be clipped to your finger. It will measure the amount of oxygen in your blood. You will also wear nose clips and breathe through a mouthpiece. Healthcare staff will monitor how you're doing:

  • Before you start to exercise, a breathing test (spirometry) may be done. This will measure the amount of air you breathe in (inhale) and breathe out (exhale) while at rest.

  • While you exercise, your heart rate, breathing, and blood pressure are checked. Exercise as long as you can. When the test is over, keep the mouthpiece in place until you are told to remove it.

  • During this test, blood samples may be taken. This may mean the staff places a small tube (catheter) so blood can be drawn during the test. This is done to measure oxygen and carbon dioxide in your blood during exercise.

After the test

You can return to your normal diet, activity, and medicines, unless your healthcare provider tells you otherwise. If you were told to skip medicines before the test, ask if you should take them now. Ask your healthcare provider how and when you will get the test results.

Risks and possible complications

Like many tests, this test has some risks. They may include:

  • Shortness of breath or wheezing

  • Rise or fall in blood pressure

  • Fainting, dizziness, or tiredness (fatigue)

  • Abnormal heartbeat or heart rate

  • Heart attack or stroke (rare)

  • Problems from the catheter, if you had one in place

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