Lung Function Tests

Lung function tests are a group of tests that check how well your lungs are working. These tests are also called pulmonary function tests, or PFTs. They may be used with other tests and information to help diagnose and monitor certain lung diseases.

There are many types of lung function tests. Most of them involve breathing through a mouthpiece. The mouthpiece is connected to a device that makes different types of measurements, such as: How much air your lungs can hold; How well you move air in and out of your lungs when you breathe; How well your lungs absorb oxygen from the air you breathe and move it into your blood; Lung function tests also help check the health of your airways.

Your airways are the parts of your body that carry air to your lungs, including your nose, throat, trachea (windpipe), and bronchial tubes that connect your windpipe to each lung. Common lung function tests include: Spirometry. This lung function test is used the most.

A spirometry test measures how much air you breathe out and how fast you can blow air out of your lungs.; Lung volume test, also called as body plethysmography. This test is the most accurate way to measure the amount of air your lungs can hold. It also measures the amount of air that remains in your lungs after you exhale as much as you can.; Lung diffusion capacity test.

This test measures how well your lungs deliver oxygen to your blood from the air you breathe.; Exercise tests. There are different types of tests that measure how well your lungs work when you are active, including: Six minute walk test; Cardiopulmonary (heart and lung) exercise test (CPET); ; Your health care provider may order one or more lung function tests, depending on the reason you need to be tested.

Why this test is done

Lung function tests are done for many different reasons. You may need testing if you:

• Have signs and/or symptoms of a breathing problem such as:
• Shortness of breath
• Wheezing
• Coughing
• A tight feeling in your chest or trouble breathing deeply
• An abnormal chest x-ray
• Have a lung condition or another type of condition that could damage your lungs
• Have been exposed to substances that can cause lung damage, such as asbestos, radiation, or certain medicines
• Are going to have surgery

Your provider may also order a lung function test as part of your routine exam.

How to prepare

Your provider will let you know how to prepare for your lung function test. To make sure your test results are accurate, follow the instructions you're give. In general:

• Wear loose, comfortable clothing.
• Don't eat a large meal within at least two hours of the test.
• You may need to avoid certain activities or foods and beverages before your test. Your provider will tell you for how long. These include:
• Heavy exercise
• Smoking
• Drinking alcohol
• Drinking or eating products with caffeine, such as coffee, colas, and chocolate
• If you use inhaler medicines (bronchodilators), you may need to stop for a period of time before testing. Your provider will tell you when to stop. But never stop taking any medicine without talking with your provider first.
• If you wear dentures, wear them for the test. They'll help you close your lips tightly around the mouthpiece.

Other names for this test

pulmonary function tests, PFTs