Pulmonary Function Tests (PFTs)
Pulmonary function tests (PFTs) are a group of tests that measure how well your lungs work. This includes how well you’re able to breathe and how effective your lungs are able to bring oxygen to the rest of your body.
Your doctor may order these tests:
- if you’re having symptoms of lung problems
- if you’re regularly exposed to certain substances in the environment or workplace
- to monitor the course of chronic lung disease, such as asthma or chronic obstructive pulmonary disease (COPD)
- to assess how well your lungs are working before you have surgery
PFTs are also known as lung function tests.
How do I prepare for pulmonary function tests?
If you’re on medications that open your airways, such as those used for asthma or chronic bronchitis, your doctor may ask you to stop taking them before the test. If it isn’t clear whether or not you should take your medication, make sure to ask your doctor. Pain medications may also affect the results of the test. You should tell your doctor about any over-the-counter and prescription pain medications you’re taking.
It’s important that you don’t eat a large meal before testing. A full stomach can prevent your lungs from inhaling fully. You should also avoid food and drinks that contain caffeine, such as chocolate, coffee, and tea, before your test. Caffeine can cause your airways to be more open which could affect the results of your test. You should also avoid smoking at least an hour before the test, as well as strenuous exercise before the test.
Be sure to wear loose-fitting clothing to the test. Tighter clothing may restrict your breathing. You should also avoid wearing jewelry that might affect your breathing. If you wear dentures, wear them to the test to ensure that your mouth can fit tightly around the mouthpiece used for the test.
If you have had recent eye, chest, or abdominal surgery or a recent heart attack, you will likely need to delay the test until you have fully recovered.
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.