Lung function tests (also called pulmonary function tests) include a variety of tests that check how well the lungs work. The most basic test is spirometry. This test measures the amount of air the lungs can hold. The test also measures how forcefully one can empty air from the lungs.
Spirometry is used to screen for diseases that affect lung volumes. It also is used to screen for diseases that affect the airways, such as COPD or asthma.
Lung volume testing is another commonly performed lung function test. It is more precise than spirometry and measures the volume of air in the lungs, including the air that remains at the end of a normal breath. In addition, a diffusing capacity test measures how easily oxygen enters the bloodstream. Exercise testing helps evaluate causes of shortness of breath. There are also tests to find out if asthma is present when the usual breathing test results are normal.
What to Expect
These tests are not painful. They are performed by a pulmonary function technician, who will require you to use maximal effort to blow out and breathe in air. The tests are repeated several times to make sure the results are accurate. When performing the test, keep the following in mind:
- You should take your daily medications prior to testing unless told otherwise.
- Do not smoke for at least six hours prior to testing.
- If you are using a short-acting inhaler that is used only as needed, do not use for six to eight hours prior to testing, if possible.
- Your doctor may give you other instructions regarding medications.
The exercise test will be performed on a bike or treadmill and you should plan to wear loose fitting, comfortable clothing and athletic shoes. You will be attached to a heart monitor and blood pressure machine to monitor your vital signs during the test. You will be given additional instructions about how to prepare for this test at the time it is ordered.