Pulmonary Function Test

What is a Pulmonary Function Test?

Pulmonary function testing, also called breathing tests, may involve one or several tests of your lungs including spirometry, lung volumes, diffusion testing, and oxygen saturation measurement by oximetry or blood gas sampling. These are tests which determine how well your lungs are functioning and most involve blowing into a tube with your nose plugged. These tests are performed by a Registered Respiratory Therapist and interpreted by an Internist. We measure the volume, flow, and oxygen transfer capabilities of your lungs. The tests can determine the cause of shortness of breath and may help confirm lung diseases such as asthma, bronchitis, or emphysema. Pulmonary function testing is very safe and a needle is only required if your doctor has required blood gases to be drawn. This test DOES involve a lot of effort on your part.

Why did my doctor order this test?

There are many lung disorders, the most common being asthma, emphysema, bronchitis, and lung fibrosis. There are also heart, muscle, and arthritic diseases which can affect the lungs. People can have symptoms such as cough, shortness of breath, and wheeziness. Your doctor will use the results of your pulmonary function test to help to diagnose breathing problems or diseases and to determine if breathing medications are of help to you or not.

How should I prepare for this test?

  • Stop taking the following puffers FOUR hours before the test: Atrovent, Berotec, Bricanyl, Combivent, & Ventolin.
  • Stop taking the following puffers TWELVE hours before the test: Accolate, Advair, Serevent, Singulair, Spiriva, & Symbicort.
  • Take all other medications as usual unless specified by your physician.
  • If you have a fever or are feeling ill please contact us at 613-938-4240 ext 5388
  • Please arrive 15 minutes before your test time so that you can register with the receptionist.
  • Please do not smoke before the test.
  • Please do not drink coffee prior to the test.
  • Bring a list of your medications and allergies.
  • You can eat before this test, but a huge meal right before the test is not recommended.

How long will the test take?

The test last approximately 45 minutes. You will be asked to perform a series of breathing tests where you must wear a nose clip over your nose and breath through you mouth into a tube connected to a machine. After the majority of breathing tests are performed you will be given three puffs (300 mcg) of Ventolin. Approximately ten minutes later the respiratory therapist will have you retry the first two breathing tests. This is a simple way of determining if the Ventolin has had an effect on your breathing.

Risks and Discomfort

A small part of the Pulmonary Function Test involves physical exertion in terms of taking rapid breaths with forceful exhalation. A small possibility of dizziness and/or difficulty breathing exists. Every effort will be made to minimize these by careful observation by the Therapist during the test. Tell the Respiratory Therapist if you experience any of these problems.


Please be aware that the Respiratory Therapist is not allowed to give you the results of your pulmonary function test. The report will be interpreted by an internist on staff. An interpreted copy will then be sent to your family doctor in approximately one week’s time.