Pulmonary Function Testing (PFT)

What is a PFT test?

A Pulmonary Function Test (PFT) is a group of tests that measure how well the lungs take in and release air and how well they move gases such as oxygen from the air into the body’s circulation. The PFT test is used to diagnose certain types of lung disease (especially asthmabronchitis, and emphysema), find the cause of shortness of breath and measure whether exposure to contaminants at work affects lung function.


How is a PFT test conducted?

Each PFT has three components:

  1. Spirometry where you breathe into a mouthpiece that is connected to an instrument called a spirometer. The spirometer records the amount and the rate of air that you breathe in and out over a period of time.  For some of the test measurements, you can breathe normally and quietly. Other tests require forced inhalation or exhalation after a deep breath.
  2. Lung volume is measured when you breathe nitrogen or helium gas through a tube for a certain period of time. The concentration of the gas in a chamber attached to the tube is measured to estimate the lung volume.
  3. Diffusion capacity where you breathe a harmless gas for a very short time, often one breath. The concentration of the gas in the air you breathe out is measured. The difference in the amount of gas inhaled and exhaled measures how effectively gas travels from the lungs into the blood.


Who would benefit from having a PFT test?

Persons who would benefit from the PFT include those with unexplained shortness of breath, chronic coughing, asthma, and COPD (chronic obstructive pulmonary disease), as well as other pulmonary disorders. The PFT can help the physician determine the root of a patient’s symptoms as well as take the necessary steps in treatment.


How do I prepare for a PFT test?

In preparation for the test, do not eat a heavy meal before the test. Do not smoke for 4 – 6 hours before the test. You’ll get specific instructions if you need to stop using bronchodilators or inhaler medications. You may have to breathe in medication before the test.