OSF Medical Group

Pulmonary Function Testing

Pulmonary function tests check how much air your lungs can hold, how quickly you move air in and out of your lungs, and how well your lungs put oxygen into and remove carbon dioxide from your blood.

These tests are quick, easy and painless, but they allow the specialists at Illinois Lung to diagnose lung disease, measure the severity of lung problems and check to see how well treatment for a lung disease is working.

What to Expect

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.

Types of Pulmonary Function Tests

Pulmonary function tests almost always include spirometry, a test that measures how much air you can breathe in and out and how fast you can blow the air out of your lungs.

The therapist will ask you to place a clip on your nose to prevent air from leaking out. Then you will breathe through a mouthpiece connected to a computer that will measure and record your results.

The therapist may also measure how your lungs respond to small amounts of bronchodilators, medicines that cause muscles in the lungs to relax.

With this test, you will perform the spirometry portion of the test, immediately after you will receive a breathing treatment with a bronchodilator medication and then do the spirometry portion of the testing again to measure how much your values have improved.

Body Plethysmograph
Another important measure is total lung capacity (or lung volume), which measures the total amount of air your lungs can hold. You will perform this test in a body plethysmograph, an enclosed transparent acrylic booth.

With the body plethysmograph, you will sit inside and breathe into the same tube used for the spirometry, but the door to the box will be closed for approximately 60 seconds.

Diffusion Capacity
Diffusion capacity testing provides information about the transfer of oxygen and other gases between your lungs and your blood.