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Pulmonary Function Test (PFT)

Test Preparation

  • No smoking 6 hours prior to the test.

  • Do not use inhalers or breathing treatments 8 hours prior to the test.

  • No caffeine 4 hours prior to the test.

About the Test

Pulmonary function tests (PFT) are used to:

  • Compare your lung function with standards to show how your lungs should be working

  • Measure the effect of lung disease on lung function

  • Identify early changes in lung function that might show a need for changes in treatment


The three tests performed during a PFT are spirometry, lung volumes and a diffusion test.

During the test, you will use a mouthpiece connected to a machine. A technician will ask you to take deep breaths in and out and to hold your breath. The technician will coach you to get the best possible results.


Please let your technician know if you are having difficulty completing the tests or if you have any questions. The PFT will take approximately 30 minutes.

After the Test

Once the test is complete you will be able to drive home. The physician will review the test, and the results will be provided to you at your next appointment or by phone.

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