Lung Cancer Team - Clinical Services

Diagnostic Services: Pulmonary Function Test

The pulmonary function test (PFT) compares the function of your lungs to predictions based on your height, age, and weight. Abnormal test results can be caused by lung diseases, such as emphysema, scarring, and asthma, and also by abnormalities in your rib cage, abdominal diseases, and heart failure.

The test measures the amount and speed of air moved in and out of your lungs. Nose clips are used to prevent air from escaping through your nose. You will need to be able to follow directions during the test. Please inform the technician if you expect problems related to hearing loss or need for an interpreter.

Please wear comfortable clothes that do not restrict your breathing. You will be asked to perform these breathing techniques several times. Sometimes a drug (broncho-dilator) is used that widens the air passages of the lungs and eases breathing; and you then repeat the test. The value of this test depends on your effort, so please try your best.

The results are given in both raw data and as a percent of  "predicted values" based on height, weight, and age. Your doctor may ask for blood to be drawn at the time of your test, to determine how much oxygen and carbon dioxide is in your blood.

All this information is used to determine what type of treatment you are a candidate for. If surgery is being discussed, a PFT will tell the surgeon how much lung can be removed or whether surgery is a good option at all. PFT's are often done for patients periodically during treatments to give the doctor an indication of how they are tolerating the treatment.