A Pulmonary Function Test (PFT) evaluates how well your lungs work. PFTs measure the amount of air in your lungs, how well the lungs move air in and out.
A respiratory therapist will guide you through each test in a special exam room that has all the lung function measuring devices. Most of the tests are quick, easy and painless, but be sure to tell the therapist if you feel light-headed, tired or uncomfortable.

Don’t eat a heavy meal right before the test, and avoid caffeinated foods or drinks. Don’t smoke or exercise strenuously for six hours before the test. On the day of the test, wear loose clothing that won’t restrict your breathing, and wear dentures to the testing if you normally wear them. Finally, just relax, breathe easy and do your best.