Pulmonary Function Test (PFT)

What is a pulmonary function test?

A pulmonary function test is actually a series of tests that measures the lung's volume and flow capacity. As the patient exhales, the machine is able to measure the volume of the gas and the flow rate generated by the patient.

Why does my doctor want me to have a PFT?

If you are having shortness of breath this test can provide your physician with valuable information. This information is used to determine the properties of the lungs. A patient with obstructive lung disease is not able to exhale fully because their lungs "trap" air. This results in both a decrease in their exhaled volume and the flow rate they can generate. A patient with a restrictive disease is able to generate adequate flow rates but has a decreased volume of air. The test that measures the volume and flow rate that a patient can exhale is called the forced vital capacity.

Two other important tests are the lung volume test and diffusion capacity test. The lung volume test actually measures the total gas volume of the lungs including what the patient is unable to exhale. This test is valuable in the diagnosis and degree of obstructive and restrictive disease. The diffusion capacity test measures the lung's ability to move gases across the alveolar-capillary membrane and into the blood stream. This information is important to evaluate patients who have fibrosis or are receiving chemotherapy.

What do I need to do before I come in for my test?

Make sure you have you physician's order. You cannot be admitted for the test without an order. Present your orders to the admission clerk and she will give you additional paperwork to bring to our department.

Do not eat 1 ½ - 2 hours before your test.

Do not use your bronchodilators for eight hours prior to your test