A Pulmonary Function Test (PFT) is a series of non-invasive tests used to assess the functioning of your lungs and diagnose respiratory conditions. These tests measure how well you can move air in and out of your lungs and how effectively oxygen is being transferred into your bloodstream.
The most common types of tests included in a PFT are:
- Spirometry: This test measures the amount of air you can inhale and exhale and how quickly you can do so. You will be asked to take a deep breath and blow into a tube connected to a spirometer, which records the airflow.
- Lung Volume Measurement: This test measures the total amount of air your lungs can hold. You will be asked to sit inside a sealed booth and breathe in and out of a mouthpiece connected to a machine called a plethysmograph.
- Diffusion Capacity Test: This test measures how well oxygen passes from your lungs into your bloodstream. You will be asked to breathe in a harmless gas and then breathe it out. The concentration of the gas is measured to assess how efficiently oxygen is transferred.

The procedure for performing a PFT generally involves the following steps:
- Preparation: You may be asked to avoid smoking, certain medications, and heavy meals before the test. It is important to follow any specific instructions given by your healthcare provider.
- Explanation: A healthcare professional will explain the procedure to you and address any concerns or questions you may have.
- Testing: You will be guided through each test. For spirometry, you will be asked to take a deep breath and forcefully exhale into the tube. Multiple attempts may be made to ensure accurate results. For lung volume measurement, you will sit inside the sealed booth and follow instructions on when to breathe in and out. The diffusion capacity test involves breathing in and out of a mouthpiece connected to a specialized machine.
- Completion: Once all the necessary tests have been performed, the healthcare provider will review the results and provide an interpretation. They may discuss the findings with you immediately or schedule a follow-up appointment to discuss the results in detail.
It’s important to note that the specific procedures and equipment used during a PFT may vary depending on the healthcare facility and the individual’s condition. It is best to consult with a healthcare professional to get detailed information about your specific PFT.