Munson Health
Pulmonary Function Tests

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by Randall B



Reasons for Test

PFTs may be used to diagnose lung conditions or diseases, such as:
These tests may also be done to:
  • Measure how much a lung problem is affecting you
  • Evaluate symptoms such as coughing , wheezing, and trouble breathing
  • Evaluate your lung function before or after a surgery
  • Determine how well a treatment is working

What to Expect

Prior to Test

  • Review your medicines with your doctor. You may need to stop taking some before testing.
  • Do not eat, smoke, or exercise 4-8 hours before testing.
  • Wear loose-fitting clothing.

Description of Test

Most tests will require you to breathe into a mouthpiece. The mouthpiece may be attached to a simple handheld device or be part of a larger machine. Examples of devices are a spirometer or peak flow meter . You may be asked to breathe in and out in different patterns and speeds. You will rest between tests.
Peak Flow Meter
Lung test peak flow meter
Copyright © Nucleus Medical Media, Inc.
Other tests that may be used in some situations include:
  • A brief period of exercise before the test.
  • Oxygen saturation test to measure the amount of oxygen in the blood. Can be measured with a small clip on your finger.
  • You may be exposed to a specific chemical called methacholine during the PFT. The test will determine if your breathing changes due to that chemical. This is only done under close and careful supervision.

After Test

Rest until you feel able to leave. You may be given medicine if testing has caused wheezing, coughing, and/or difficulty breathing.

How Long Will It Take?

20-45 minutes

Will It Hurt?

The test does not hurt. You may feel symptoms of your lung condition during or immediately following testing.


American Lung Association




Canadian Lung Association

COPD Canada



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Chang J, Mosenifar Z. Differentiating COPD from asthma in clinical practice. J Intensive Care Med . 2007;22(5):300-309.

Chu MW. Introduction to pulmonary function. Otolaryngol Clin North Am . 2008;41:387-396.

Crapo RO, Casaburi R, et al. Guidelines for methacholine and exercise challenge testing (1999). Am J Respir Crit Care Med . 2000;161:309.

Pulmonary Function Tests (PFTs). Duke University Health System. website. Available at: . Accessed November 12, 2010.

Walsh JM. Interpreting pulmonary function test. Loyola University Medical Education Network website. Available at: . Accessed October 30, 2006.


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