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Quick Facts

Pulmonary Function Testing (PFT)

By

The Manual's Editorial Staff

Last full review/revision Mar 2021| Content last modified Mar 2021
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What is pulmonary function testing?

Pulmonary refers to your lungs. Pulmonary function tests check how well your lungs are working.

  • During the test, you breathe in and out of a tube connected to the pulmonary function device

  • The device measures how much air goes in and out of your lungs and how fast the air moves

  • Pulmonary function tests look for lung diseases, such as asthma or emphysema

How do doctors do pulmonary function tests?

Doctors can use several different devices. The most common ones are:

  • Spirometers

  • Peak flow meters

Spirometers

A spirometer is a device you breathe into to measure how much air your lungs can hold and how fast you can blow air out of your lungs. Doctors use a spirometer:

  • To see if something is blocking your breathing passages

  • To see how much air your lungs hold

  • To check how strong your breathing muscles are

Spirometer

A spirometer can be used to measure how much air the lungs can hold and how quickly air can be exhaled.

Spirometer

Peak flow meters

A peak flow meter measures only how fast you can blow air out of your lungs. It's a small device you hold in your hand. If you have asthma, your doctor may give you one to use at home to keep track of how you're doing.

Why do doctors do pulmonary function tests?

Doctors do pulmonary function tests to see how well your lungs are working. They may do them if you have or may have a disease that affects your lungs or breathing muscles, such as:

Doctors can use pulmonary function tests to check for:

  • What kind of lung disease you may have

  • How severe your lung disease is

  • How well your breathing medicine is working

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