What PFT means?
Pulmonary function test: A test that is designed to measure how well the lungs are working. Abbreviated PFT. PFTs gauge how the lungs are expanding and contracting (when a person inhales and exhales) and measure the efficiency of the exchange of oxygen and carbon dioxide between the blood and the air within the lungs.
How is a pulmonary function test performed?
You will be asked to empty your lungs by gently breathing out as much air as you can. Then you will breathe in a quick (but deep breath), hold your breath for 10 seconds, and then breathe out as instructed. You will do the test several times. It usually takes about 30 minutes to complete this test.
Why might I need pulmonary function tests?
There are many different reasons why pulmonary function tests (PFTs) may be done. They are sometimes done in healthy people as part of a routine physical. They are also routinely done in certain types of work environments to ensure employee health (such as graphite factories and coal mines). Or you may have PFTs if your healthcare provider needs help to diagnose you with a health problem such as:
- Respiratory infections
- Trouble breathing from injury to the chest or a recent surgery
- Chronic lung conditions, such as asthma, bronchiectasis, emphysema, or chronic bronchitis
- Asbestosis, a lung disease caused by inhaling asbestos fibers
- Restrictive airway problems from scoliosis, tumors, or inflammation or scarring of the lungs
- Sarcoidosis, a disease that causes lumps of inflammatory cells around organs, such as the liver, lungs, and spleen
- Scleroderma, a disease that causes thickening and hardening of connective tissue
PFTs may be used to check lung function before surgery or other procedures in patients who have lung or heart problems, who are smokers, or who have other health conditions. Another use of PFTs is to assess treatment for asthma, emphysema, and other chronic lung problems. Your healthcare provider may also have other reasons to advise PFTs.
How do I get ready for pulmonary function tests?
Your healthcare provider will explain the procedure to you. Ask him or her any questions you have. You may be asked to sign a consent form that gives permission to do the procedure. Read the form carefully. Ask questions if anything is not clear.
Tell your healthcare provider if you take any medicines. This includes prescriptions, over-the-counter medicines, vitamins, and herbal supplements.
Make sure to:
- Stop taking certain medicines before the procedure, if instructed by your healthcare provider
- Stop smoking before the test, if instructed by your healthcare provider. Ask your provider how many hours before the test you should stop smoking.
- Not eat a heavy meal before the test, if instructed by your healthcare provider
- Follow any other instructions your healthcare provider gives you
Your height and weight will be recorded before the test. This is done so that your results can be accurately calculated.
What happens during pulmonary function tests?
You may have your procedure as an outpatient. This means you go home the same day. Or it may be done as part of a longer stay in the hospital. The way the procedure is done may vary. It depends on your condition and your healthcare provider's methods. In most cases, the procedure will follow this process:
- You’ll be asked to loosen tight clothing, jewelry, or other things that may cause a problem with the procedure.
- If you wear dentures, you will need to wear them during the procedure.
- You’ll need to empty your bladder before the procedure.
- You’ll sit in a chair. A soft clip will be put on your nose. This is so all of your breathing is done through your mouth, not your nose.
- You’ll be given a sterile mouthpiece that is attached to a spirometer.
- You’ll form a tight seal over the mouthpiece with your mouth. You’ll be instructed to inhale and exhale in different ways.
- You will be watched carefully during the procedure for dizziness, trouble breathing, or other problems.
- You may be given a bronchodilator after certain tests. The tests will then be repeated several minutes later, after the bronchodilator has taken effect.
What happens after pulmonary function tests?
If you have a history of lung or breathing problems, you may be tired after the tests. You will be given a chance to rest afterwards. Your healthcare provider will talk with you about your test results.
Why are these tests done?
Your doctor will order these tests to determine how your lungs are working. If you already have a condition that’s affecting your lungs, your doctor may order this test to see if the condition is progressing or how it’s responding to treatment.
PFTs can help diagnose:
- chronic bronchitis
- respiratory infections
- lung fibrosis
- bronchiectasis, a condition in which the airways in the lungs stretch and widen
- COPD, which used to be called emphysema
- asbestosis, a condition caused by exposure to asbestos
- sarcoidosis, an inflammation of your lungs, liver, lymph nodes, eyes, skin, or other tissues
- scleroderma, a disease that affects your connective tissue
- pulmonary tumor
- lung cancer
- weaknesses of the chest wall muscles
What happens during the tests?
Your PFTs may include spirometry, which measures the amount of air you breathe in and out. For this test, you’ll sit in front of a machine and be fitted with a mouthpiece. It’s important that the mouthpiece fits snugly so that all the air you breathe goes into the machine. You’ll also wear a nose clip to keep you from breathing air out through your nose. The respiratory technologist will explain how to breathe for the test.
You may then breathe normally. Your doctor will ask you to breathe in and out as deeply or as quickly as you can for several seconds. They may also ask you to breathe in a medication that opens your airways. You’ll then breathe into the machine again to see if the medication affected your lung function.
A plethysmography test measures the volume of gas in your lungs, known as lung volume. For this test, you’ll sit or stand in a small booth and breathe into a mouthpiece. Your doctor can learn about your lung volume by measuring the pressure in the booth.
Diffusion capacity test
This test evaluates how well the small air sacks inside the lungs, called alveoli, work. For this part of a pulmonary function test, you will be asked to breathe in certain gases such as oxygen, helium, or carbon dioxide.
You may also breathe in a “tracer gas” for one breath. The machine can detect when you breathe out this gas. This tests how well your lungs are able to transfer oxygen and carbon dioxide to and from your bloodstream.
What are the risks of pulmonary function tests?
A PFT can cause problems if:
- you’ve recently had a heart attack
- you’ve recently had eye surgery
- you’ve recently had chest surgery
- you’ve recently had abdominal surgery
- you have a severe respiratory infection
- you have unstable heart disease
PFTs are usually safe for most people. However, because the test may require you to breathe in and out quickly, you may feel dizzy and there’s a risk that you may faint. If you feel lightheaded, tell your doctor. If you have asthma, the test may cause you to have an asthma attack. In very rare cases, PFTs may cause a collapsed lung.
Pulmonary Function Test Results
Certain things can make PFTs less accurate-
- The degree of patient cooperation and effort
- Use of medicines that open the airways (bronchodilators)
- Use of pain medicines
- Stomach bloating that affects the ability to take deep breaths
- Extreme tiredness or other conditions that affect a person’s ability to do the tests (such as a head cold)