Pulmonary Lung Function Testing (PFT)

What is a Lung Function Test?

Lung function tests, which are also called pulmonary function tests (PFT), are tests that can be carried out to find out how well your lungs and airways are working. Lung function tests can assist in the diagnosis of respiratory (breathing) conditions. They can also work out how severe a condition is and help monitor the response to treatments.

They are a simple, non-invasive way to investigate your lung function and performance under specific conditions.

Why are Lung Function Tests Performed?

Lung function tests are often used to help diagnose or assess asthma and chronic obstructive pulmonary disease (COPD). They are also used to assess other conditions that affect breathing, including lung scarring and illnesses that affect the chest or breathing muscles.

What Happens During a Lung Function Test?

The testing involves a series of breathing exercises, which provide a more detailed assessment of lung physiology. You will perform these breathing exercises into a mouthpiece, in different patterns.

Lung function tests usually take between 45 minutes and one hour, though this can vary based on the individual.

How to Prepare for a Lung Function Test

Here are a few pointers to help you prepare, as a general rule. You will receive specific instructions based on the type of test you’re undertaking:

  • Wear comfortable clothing that doesn’t restrict your breathing
  • Bring any inhalers you use, if relevant
  • Refrain from the following:
    • Drinking caffeine or alcohol (4 hours prior)
    • Eating a significant amount (2 hours prior)
    • Exercising (1 hour prior)
    • Smoking (1 hour prior)


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