What is a lung function test?
Lung function tests, also called pulmonary function tests (PFTs), are non-invasive tests that measure how well the lungs are working. This information helps your doctor plan the best course of treatment.
Types of Tests
Your doctor might use one or more tests depending on what they are looking for.
Breathing (Spirometry)
This test measures how much air you can breathe in and how fast you can breathe out using a spirometer, a small device attached to a mouthpiece. It helps diagnose lung and airway diseases, and it can also check for scarring.
What to Expect
During this test, you take a deep breath then blow as hard and fast as you can into a mouthpiece.
Lung Volume (Plethysmography)
This test measures your total lung capacity and how much air is in your lungs after you take in a deep breath.
What to Expect
You’ll sit in a clear booth and perform breathing exercises for about 15 minutes.
Gas Transfer (DLCO)
This test measures how your lungs transfer oxygen from the air your breathe to your bloodstream.
What to Expect
You’ll breathe in oxygen mixed with very small amounts of helium and carbon monoxide, which are completely harmless at the low levels used. Then you’ll be asked to hold your breath for 10 seconds before exhaling fully.
Bronchial Challenge
Also called airway provocation, this test measures how sensitive your lungs are. It can help rule out whether the problem is caused by your lungs or something else.
What to Expect
You’ll breathe in gradually increasing doses of a medication that causes mild irritation. People with sensitive lungs will be affected by a much lower dose than people with healthy lungs.
