Pulmonary Function Tests (PFTs)


This is a range of tests that show how well your lungs are working. We use them to check the health of your lungs, and to monitor lung conditions and treatments. Let's look at some of the different tests.


One test is called "spirometry." It measures airflow. For this test, you breathe through the mouthpiece of a device called a "spirometer." A clip on your nose makes sure you only breathe through your mouth. As you breathe, a machine measures the air moving in and out of your lungs.

Lung volume

Another test we use is called a "lung volume" test. It's similar to a spirometry test, but you sit in a clear, airtight box. As you breathe, we measure the change in air pressure inside the box to see how much air your lungs hold.

Other breathing tests

Other breathing tests can give us information about the gasses exchanged when you breathe. One measures the amount of nitric oxide in the air you breathe out. Another shows how well oxygen is getting from your lungs into your blood.

Measuring gasses in the blood

And finally, we can measure the gasses in your blood. A pulse oximetry test uses a probe placed on the surface of your skin to measure oxygen levels in the blood flowing beneath it. An arterial blood gas test measures gas levels directly. For this test, we take a sample of blood from an artery. Usually, we take it from the wrist.


For more info about pulmonary function tests, talk to your doctor.