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Pulmonary Function Testing (PFT)

A great deal of information about the function of your lungs can be determined by performing a Pulmonary Function Test (PFT). This test tells your physician how much air you inhale and exhale with each breath, how you move air in and out of your lungs and how well your lungs deliver oxygen to your bloodstream.

Preparations / Restrictions

DO NOT use an inhaler or take a breathing treatment for a minimum of 4 hours before testing. If you use your inhaler or treatment within 4 hours, please call to reschedule your PFT. If you need to eat before the test, eat a light meal or snack.

What to Expect

You may be asked to go to the Laboratory to have blood drawn. The blood is taken from the wrist and is tested for its oxygen, carbon dioxide, and pH levels. This is referred to as Arterial Blood Gases (ABGs). The ABGs are needed to completely evaluate your lung function. You will be asked to return to the Cardiopulmonary Department for the PFT.

The PFT is done by breathing into a mouthpiece connected to the pulmonary function machine. You are asked to complete a series of breathing maneuvers during the testing that helps evaluate your lung function. The Respiratory Therapist instructs and coaches you on each maneuver. You may be given a respiratory medication during your test. Depending on the total maneuvers ordered, the test(s) may take from 30 minutes to 2 hours.


The test results are sent to an interpreting physician. The interpreted results are then sent to your physician who discusses the report with you.

Frequently Asked Questions

Should I use my inhaler or nebulizer before this test?
No. This requires your test to be delayed or re-scheduled. Your medication could alter the test results.

How close to test time am I allowed to use my inhaler?
No less than 4 hours prior to your test.

Do I need to bring a list of my medications?
Yes. This information is useful for the physician's interpretation of your test.