Understanding Pulmonary Function Test: Healthy Lung Month

November is Lung Month in Canada, providing an opportunity to raise awareness about lung cancer and other pulmonary diseases, and the actions that can be taken to prevent them. Pulmonary function testing is an important aspect of this month-long campaign. This article provides a short guide to help enhance your understanding of pulmonary function testing. 

What Are Pulmonary Function Tests?

Pulmonary function tests (PFTs) are designed to show how well a person’s lungs are working. They test a number of variables, including lung volume, capacity, rates of flow and gas exchange. More specifically, they measure the following:

• Tidal volume – the amount of air breathed in or out
• Minute volume – The total amount of air breathed out per minute

• Vital capacity – Total volume breathed out after filling your lungs as much as possible 

• Functional residual capacity – Amount of air left in the lungs after breathing out normally

• Residual volume – Amount of air left in the lungs after forcing breath out of your lungs

• Total lung capacity – Volume of air in the lungs when filled as much as possible

• Forced vital capacity (FVC) – Amount of air breathed out during three rounds of the test

• Forced expiratory volume – Amount of air breathed out during three rounds of the test

• Forced expiratory flow – Average rate of flow during the middle of the test

• Peak expiratory flow rate – Fastest rate that you can force air out of your lungs

The information can help your medical practitioner assess your lung function, diagnose any potential conditions, and decide on the right treatment. 

Types of Pulmonary Function Tests

There are four types of PFTs most often carried out by medical practitioners: spirometry, lung volume tests, lung diffusion capacity tests, and pulmonary exercise tests:

• Spirometry measures the amount of air you exhale and how fast you can empty your lungs. This is used to diagnose lung diseases that affect the airways, such as asthma.

• Lung volume tests measure the volume of air your lungs can hold, and the amount that remains after you exhale.

• Lung diffusion capacity test measures how easily oxygen enters the bloodstream

• Pulmonary exercise tests evaluate how well your lungs work when active, such as when walking or doing light exercise.

How is a Pulmonary Test Done?

Pulmonary Function Tests are usually carried out in a dedicated department of a hospital or medical centre. The nurses, technicians or other professionals conducting the tests will tell you exactly what to do. There are various types of instruments involved, depending on which test is being done and how the facility is equipped. PFTs are non-invasive and they involve breathing into a mouthpiece that is connected to a meter which measures the relevant variables, such as volume, flow rate and capacity.

To prepare for a lung function test, it is best to wear loose-fitting clothes, and try not to eat or drink for a few hours beforehand. A full stomach can make it difficult to draw a deep breath. Be sure to follow any instructions your provider gives you. You may be required to stop taking certain medications until the test is done.

Why You Might Need a Lung Function Test

PFTs are carried out with one or more of the following purposes in mind:

• Test your lungs to check that they are functioning healthily
• Ensure that your lungs are healthy for certain treatments that may be prescribed for you
• Measure how certain medicines may be affecting your lungs
• Ensure that one lung is in good working order if you may need to have the other one removed

You may need to take a PFT if you are experiencing difficulty breathing, in order to determine what the problem is and how it can be treated. You may also need to take a test if you are currently undergoing a treatment, in order to test the efficacy of the treatment or check for certain side effects. PFTs are also good screening tests to help you ensure that your pulmonary system is strong and healthy.

WELL Health Diagnostic Centres has PFT facilities at most of our locations around Ontario. If you need a pulmonary function test, you will need to get a referral from your medical practitioner. Contact your nearest WELL Health Diagnostic Center for more information or to book an appointment.