Pulmonary function tests are a broad range of tests that are usually done in a health care provider’s office or a specialized facility. They measure how well the lungs take in and exhale air and how efficiently they transfer oxygen into the blood.
Spirometry measures how well the lungs exhale. The information gathered during this test is useful in diagnosing certain types of lung disorders, but is most useful when assessing for obstructive lung diseases (especially asthma and chronic obstructive pulmonary disease, COPD).
How the test is performed
In a spirometry test, a person breathes into mouthpiece that is connected to an instrument called a spirometer. The spirometer records the amount and the rate of air that is breathed in and out over a specified time. Some of the test measurements are obtained by normal, quiet breathing, and other tests require forced inhalation or exhalation after a deep breath.
Why the test is performed
The test is performed to diagnose certain types of lung disease (especially asthma, bronchitis, and emphysema), to determine the cause of shortness of breath, or to measure whether occupational exposure to contaminants affects lung function. It can also be used after the administration of medications to assess their effect, and to measure progress in disease treatment.