Pulmonary Function Tests are a single or combination of tests to help patient's doctors understand more about how the lungs are functioning. These tests require special equipment, trained technologists to perform the tests, and skills in interpreting the tests. Below will briefly explain the various parts of a pulmonary function test.

Spirometry
Spirometry is a tool used to evaluate how well air is moving into and out of the lungs. When performing this procedure the individual being tested exhales as hard and fast as they can and then inhales rapidly. By evaluating information gathered during this test, we can determine certain characteristics about air flowing into and out of the lungs. The person being tested is then compared to a "normal" group. This normal group is simply a selected group of people of the same age, height, race and sex, who do not have lung disease to use for comparison.

From the information gathered with this test we make certain deductions about what is happening throughout the lung. In particular we comment on OBSTRUCTIVE LUNG DISEASE and degrees of this disease process with this testing.

Obstructive lung disease is simply put, a problem with the airways that do not allow airflow to move smoothly from the alveoli (air sacs of the lungs) and smallest airways out through your trachea (main windpipe) and ultimately out through your mouth when you exhale or inhale. There are a number of common and uncommon processes that can lead to this kind of a problem. Some of the more common include emphysema, asthma and chronic bronchitis.

Bronchodilator testing with spirometry
This test is performed when an obstruction is identified by the initial spirometry. A bronchodilator is a medication which will help open up airways which have bronchoconstriction (the airway is partially closed off). The goal of this test is to identify how much if any of a patient's obstructive disease can be reversed. This information is used both to clarifying diagnosis and to help decide on medications for treatment.

Body Plethysmography - Lung volume assessment
Another tool used to assess lung function is body plethysmography. With this tool, the volumes of the lung are evaluated. Although the lung would appear to have only two obvious volumes, empty and full, there are actually four different volumes and then four combinations of volumes known as capacities that are used to assess the lung. Body plethysmography is the most accurate means available at this time to assess lung volumes.

Diffusing capacity (DLCO)
This test is used to evaluate how well oxygen moves into and out of the lungs. Certain diseases will lead to difficulties in getting oxygen from in the alveoli (air sac in the lung) into the blood where it is carried to the rest of the body. Identifying problems with this process in the lung can identify people at risk for needing oxygen. With this additional information, the pulmonary function test interpretation is also greatly improved.

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