Hospital  >  Departments  >  Medicine  >  Divisions  >  Respirology  >  Pulmonary Function Test Lab

Pulmonary Function Test Lab

What is a Pulmonary Function Test?

The Pulmonary Function Test, also commonly known as a Breathing Test, is designed to measure how well your lungs are working. You will be asked to breathe in and out through different machines, just as if you were blowing up a large balloon or blowing out a dozen candles all in one breath. The results will provide an objective assessment of your lung functions to your doctor, to confirm or rule out a diagnosis, to evaluate effectiveness of current treatment or other information. A complete test usually takes about ONE HOUR plus any additional tests your doctor may have requested.

Pulmonary Function Test includes one or any combination of the following (click to learn more)

  • Spirometry with or without a bronchodilator
    You will be asked to blow into a machine as fast and as hard as you possibly can.
    Your doctor may want to know whether a puffer (bronchodilator) helps your breathing, especially if this is your first time. Unless you received a specific instruction from your doctor and your breathing condition is able, you should not take any bronchodilator medication before the test: 4 hrs for Ventolin and Atrovent, etc; 12 hrs for Symbicort, Advair and Spiriva, etc.
  • Lung Volumes
    This is a test to measure the size of your lungs.
  • Diffusion Capacity
    This is a test to measure how efficiently oxygen gets into your blood. You will be asked to breathe in a test gas and hold your breath for a few seconds and then blow out the gas from your lungs for analysis. This test is sensitive to carbon monoxide in your lungs; therefore you should not smoke at least ONE hour before the test.
  • Respiratory Muscle Strength
    This is a test to measure the strength or power of your breathing muscles. You will be asked to blow out or breathe in as hard as you can against a blockage.
  • Exercise Oximetry
    This test is to measure your exercise capacity and oxygen level while you are walking on the treadmill or walking in the hallway. You may be asked to see how far you can walk in 6 minutes while breathing room air and/or supplemental oxygen. Wear suitable clothing and shoes for exercise.
  • Exercise-induced Bronchoconstriction
    This test is to measure your lung function before and after exercise on the treadmill for 6 minutes while your heart rate and oxygen level are monitored. Wear suitable clothing and shoes for exercise. Do not do any exercise on the day of your appointment. Do not take any puffer 1-2 days before your appointment. A bronchodilator puffer will be given to you if you feel your chest feels tight after the exercise.

 Click to download the pulmonary function test information.

  • Methacholine Challenge
    This is a test to measure the sensitivity of the airways by inhaling different concentrations of Methacholine Mist. If you develop chest tightness or coughing, you will be given a puffer to relieve the symptoms. The puffer (a bronchodilator) works quickly to provide relief.

 Click to download the methacholine challenge information.

General Preparations

  • Fasting is not required, but avoid eating a heavy meal at least 2 hours before test.
  • Depending on the type of tests, you may be asked to withhold certain breathing medication.
  • Wear loose comfortable clothing.
  • Do not smoke at least ONE hr before test.
  • If you are unable to follow verbal instruction in English, please bring someone who can interpret for you.
  • Postpone this test if you have a flu, fever, severe headache or diarrhea.
  • If you are unable to keep the appointment, please call the Laboratory to re-schedule as soon as possible.
  • Call the Laboratory if you have any questions.
  • Please arrive for your appointment on time. (Your test may be delayed or re-scheduled for late arrival.)

Location and contact

Respirology division

Sunnybrook Health Sciences Centre
2075 Bayview Avenue,
A-wing, 4th floor,
room A4 59
Toronto, ON M4N 3M5

Phone: 416-480-6100 ext. 64758
Fax: 416-480-5153
or email to:

Division Head:
Dr. Anu Tandon

Pulmonary Function Test Lab

Pulmonary Function Testing is available by referral

PFT referral form

Phone: 416-480-4427
Fax: 416-480-4186