Pulmonary Function Tests (PFTs)
Pulmonary Function Tests
What is a Pulmonary Function Test (PFT)?
Pulmonary function tests (PFTs) are a series of different breathing tests led by a trained pulmonary function technologist, usually done at a hospital or clinic. There are national standards and guidelines that help make sure that everyone does and interprets pulmonary function tests in the same way. To learn about your lung health, your doctor may want you to have several pulmonary function tests done including spirometry, lung volumes, and airway resistance. Most of these breathing tests are done by blowing into a tube while sitting in a chair.
Lung function tests (also called pulmonary function tests, or PFTs) evaluate how well your lungs work. The tests determine how much air your lungs can hold, how quickly you can move air in and out of your lungs, and how well your lungs add oxygen and remove carbon dioxide from your blood. The tests can diagnose lung diseases and measure the severity of lung problems.
How do I prepare for my PFT
Before you have PFTs, you may get specific instructions on how to get ready for the tests, such as:
- Wear loose clothing which will not restrict your ability to breathe deeply.
- Avoid large meals prior to your test time which will make it more comfortable for you to breathe deeply.
- Don’t use your inhalers on the day of the test, if possible.
At your appointment:
- The equipment will be set up for you after being cleaned and disinfected, including a clean mouthpiece.
- The technologist will tell you what to do before each test. Listen carefully and follow the coaching from the technologist. If you don’t understand what to do, ask him or her to tell you in a different way.
What is Spirometry?
Spirometry is the first lung function test done. It measures how much and how quickly you can move air out of your lungs.
Spirometry is a very common test to help you and your doctor understand your asthma, emphysema, or chronic bronchitis better, and check how it is improving with treatment.
Spirometry measures how much air you can inhale (breathe in) and exhale (breathe out) as well as how fast you can exhale. For this test, you may be asked to breathe quickly, forcefully, or slowly. You breathe into a mouthpiece attached to a recording device (spirometer). The information collected by the spirometer may be printed out on a chart called a spirogram.
The test is always repeated at least three times and often more to be sure that the test is reliable.
Your doctor may order a bronchodilator to be given as part of spirometry. A bronchodilator is an inhaled medication that may dilate, or open up, your airways. Spirometry is often done before and after the bronchodilator to show any response to the medicine. Your response may help your doctor find out what kind and how much, if any, airway disease you may have, and whether you need medication to improve your breathing.
What we can learn from PFTs?
A doctor will look over the results of your PFTs and see how you are doing by comparing them to predicted values normal for a person your age, height, sex and ethnicity. Height is important because taller people may have bigger lungs. There are many things that can change the results in PFTs. These include not only the health of your lungs but also the skill of the person testing you, and your effort. A medical diagnosis is not likely to be made from PFTs alone.
Most lung diseases are labeled either as restrictive or obstructive. They are not the names of actual lung diseases, but the labels help group types of lung diseases together. Asthma is an obstructive disease, which means that it causes people to have trouble breathing out.
Restrictive lung disease are Emphysema, and Chronic Bronchitis.
Words like mild, moderate, or severe may be used to describe how severe the problem is. Ask your doctor to explain the results so that you know what they mean for you.
A PFT may be repeated as often as your doctor thinks it is needed. Lung problems can be checked for change by regular pulmonary tests. Keep in mind that quality of life is not found in the results of your PFTs. Many people live full lives with limited lung function. The key is to look for ways to keep or improve your quality of life, including exercise, breathing techniques, proper medications, equipment aids and social or emotional support.