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Definition

Pulmonary function tests (PFTs) are a group of breathing tests. They can show how well your lungs are working. PFTs may measure:

  • How much air you can blow out
  • How much air your lungs can hold at different times
  • How fast you are blowing air out

Respiratory System

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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
Possible Complications

There are no major complications associated with this procedure.

What to Expect
Prior to Test
  • Review your medications 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.

Tell the technician right away if you have breathing problems, pain, or dizziness during testing.

Peak Flow Meter

Lung test peak flow meter

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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 medication 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.

Results

Your doctor will compare the results of your tests with normal values based on your age, sex, and height, or previous test results. Your doctor will discuss the results with you and decide if further testing or treatment is needed.

Call Your Doctor

After the test, call your doctor if any of the following occurs:

  • Headaches, nausea, muscle aches, lightheadedness, or general ill feeling
  • Shortness of breath or difficulty breathing
  • Wheezing or persistent coughing
  • Chest pain

RESOURCES:

American Lung Association
http://www.lung.org

Family Doctor—American Academy of Family Physicians
http://familydoctor.org

CANADIAN RESOURCES:

COPD Canada
http://www.copdcanada.ca

The Lung Association
http://www.lung.ca

References:

Birnbaum S, Barreiro TJ. Methacholine challenge testing: identifying its diagnostic role, testing, coding, and reimbursement (review). Chest. 2007;131(6):1932-1935.

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. DukeHealth.org website. Available at: http://cancer.dukemedicine.org/cancer/health_library/care_guides/treatment_instructions/pulmonaryfunctiontesting. Accessed September 26, 2014.

Barreiro TJ, Perillo I, et al. An approach to interpreting spirometry. Am Fam Physician. 2004;69(5):1107-1115.



Last reviewed August 2014 by Michael Woods, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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