Pulmonary Function Lab

The respiratory therapists work closely with our team of respirologists, who interpret the test results and use the information to diagnose and treat your condition. 

Please arrive at the lab 15 minutes before the start of your appointment to check in.

Pulmonary function tests

Pulmonary function tests (PFTs) measure how well your lungs work. Depending on your specific needs, you may get a combination of tests or only one. Pulmonary function tests help diagnose conditions such as:

• Asthma
• Chronic obstructive pulmonary disorder (COPD)
• Pulmonary fibrosis

Spirometry

Spirometry is the most common pulmonary function test. It measures the amount of air you can inhale and exhale.

During the test, you breathe into a mouthpiece connected to a device called a spirometer. The spirometer measures the movement of air as you breathe in and out. In some cases, your respiratory therapist may ask you to inhale medications that expand your airways as part of the test.

Wear comfortable clothing for a spirometry test. Please follow all the instructions that are given to you about taking your respiratory medication before the test.

You can go back to regular activities after your test.  

Lung plethysmography

Lung plethysmography measures the amount of air in your lungs while you inhale.

During a lung plethysmography, you sit on a chair inside a clear plastic box. A respiratory therapist measures the change in pressure inside the box during the test to determine your lung volume.

The respiratory therapist will place a clip on your nose. This helps make sure you breathe only through your mouth during the test.  

When you begin the test, the respiratory therapist will close the box and you will breathe into a mouthpiece connected to a machine called a plethysmograph. It measures the amount of air left in your lungs after you inhale and exhale.  

Wear comfortable clothing for a lung plethysmography test. Follow all instructions we give you about taking your respiratory medication before the test.  

You can go back to regular activities after your test.  

Lung diffusion

Lung diffusion measures how well your lungs move oxygen to your blood. During a lung diffusion test, you place your mouth onto a mouthpiece attached to a machine and breathe normally. The machine delivers air mixed with a small amount of carbon dioxide and methane or helium through the mouthpiece.

Throughout the test, your respiratory therapist will give you instructions on how to breathe and when to hold your breath.  

Wear comfortable clothing to your lung diffusion test. Please follow all the instructions that are given to you about taking your respiratory medication before the test.

You can go back to regular activities after your test.  

Methacholine challenge test  

A methacholine challenge test helps health-care providers see how your lungs react to methacholine, which is a medication that narrows the airway. If your lungs respond very strongly to the methacholine, you may have asthma.  

Before your methacholine test, a respiratory therapist will perform a spirometry test to test your breathing.  

Then you will inhale your first dose of methacholine through a nebulizer. A nebulizer is a small device that turns the liquid methacholine into a mist. You breathe in the mist through a mouthpiece.  

After receiving the dose of methacholine, you have another spirometry test. How often this process is repeated depends on the effect the methacholine has on your breathing.

Once the test is complete, the respiratory therapist administers a medication that opens up your airways and makes sure that your lung function has returned to normal.  

Wear comfortable clothing for you methacholine challenge test. Please follow all the instructions that are given to you about taking your respiratory medication before the test. 

Cardio-pulmonary exercise test

A cardio-pulmonary exercise test helps health-care providers see how your heart and lungs respond to exercise. A cardio-pulmonary exercise test may be recommended if you experience shortness of breath.

A respiratory therapist may perform a spirometry test or other pulmonary function tests before you begin.

During the test, you will run on a treadmill or ride a stationary bike in the lab while we monitor your breathing, oxygen levels and heart activity.

A cardio-pulmonary exercise test evaluates your body’s response to exercise and can help diagnose the following conditions:

• Exercise-induced asthma
• Pulmonary hypertension
• Cardiovascular diseases

Please do not smoke on the day of your test. Also, please inform the respiratory therapist of the following:

• Recent surgery within the last four weeks
• A history of aortic or brain aneurysms
• Episodes of coughing up blood
• Recent stroke
• Infectious disease, such as COVID-19 or tuberculosis
• Any issues with your heart, such as angina or uncontrolled blood pressure

It is important to follow all the instructions that are given to you about taking your respiratory medication before the test.

After your cardio-pulmonary exercise test, you can resume your regular activities.

What to bring

• Health (OHIP) card valid health-care coverage
• Wear comfortable clothing  
• Running shoes, if you are having a cardio-pulmonary exercise test

How to access our services

You need a referral from a health-care provider to be seen at the lab. Visit our referral criteria for more information.