Pulmonary Function Tests

What are breathing tests?

These are tests that measure how well your lungs are working. They are also called “pulmonary function tests” (“PFTs”). Specifically, breathing tests measure:

• How much air you can breathe in and out of your lungs
• How fast you can breathe the air out of your lungs
• How much oxygen gets into your blood from your lungs

Why might I need breathing tests?

Your doctor might order breathing tests to:

• Find the cause of symptoms such as chronic cough, noisy breathing (wheezing), or trouble breathing
• Check if a known lung condition is mild or severe, or changes over time – Lung conditions that are commonly followed with breathing tests include:
• Asthma
• Chronic bronchitis
• Pulmonary fibrosis
• Chronic obstructive pulmonary disease (“COPD”)
• Check how well your inhaler medicines are working
• Check how well your lungs are working before you have surgery

How do I prepare for breathing tests?

Your doctor or nurse will tell you if you need to do anything special to prepare. If you use an inhaler for asthma, your doctor might have you wait to take your medicine until after the test (instead of before).

What are the different breathing tests?

The different breathing tests include:

• Spirometry – This is the most common breathing test. It involves breathing in as deeply as you can, and then breathing out as hard and as fast as you can into a tube. The tube is attached to a machine called a “spirometer.” The doctor, nurse, or technician gives you specific directions about how to breathe for the test. It measures how much air you can breathe in and out of your lungs and how fast you can breathe the air out of your lungs.

During the test, the doctor, nurse, or technician might give you medicine to open up your airways. The medicine comes in an inhaler. Then, you repeat the spirometry test to see whether the medicine affected your breathing.

• Lung volume measurement – This measures how much air is in your lungs. Some diseases increase or decrease the amount of air in your lungs. The test might involve sitting in a large glass box that looks like a phone booth. You breathe in and out through a tube. The technician might ask you to pant (breathe in and out quickly) during the test. Lung volume can also sometimes be measured while you breathe certain mixtures of gases through a tube.
• Diffusing capacity – This measures how well oxygen gets from your lungs into your blood. It involves breathing in a certain gas, holding your breath for about 10 seconds, and then breathing out into a tube.
• 6-minute walk test – This measures how far you can walk in 6 minutes. It also measures how much oxygen is in your blood before, during, and after you walk. You wear a sensor on your finger that measures how much oxygen is in your blood.
• Arterial blood gas – This measures how much oxygen is in your blood. It involves having blood drawn from an artery in your wrist. The blood sample is sent to a lab for tests.

What are the downsides of breathing tests?

It depends on the test. For instance, breathing in and out fast and hard during spirometry can make people cough, or feel lightheaded or dizzy. It can also cause a feeling of pressure in the chest, belly, or head.

YouTube: