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What are Pulmonary Function Tests (PFTs)?

Your doctor may order pulmonary function testing to appropriately categorize known or suspected lung disease, including asthma, chronic obstructive lung disease (COPD), and restrictive lung diseases, among others.

The following three types of PFTs would be the most common types ordered by your doctor:

Spirometry is a simple and common type of PFT, typically performed at a pulmonologist’s (lung doctor) office. By breathing in and out through a tube connected to a spirometry machine at different strengths and lengths of time, useful information is collected and organized for your doctor to review. This simple test helps to diagnose and specify the severity of lung disease present. It can also help to see if medications are helping if follow up spirometry is performed at a later date.

Plethysmography is another common PFT, which is also non-invasive in useful in diagnosis and management of lung disease. This type of PFT measures the amount of air you can take in with a deep inhale, and also the amount leftover after breathing out deeply.

Diffusion capacity, also a type of PFT, helps to determine how effectively your lungs are able to take in oxygen to be used throughout your body and to get rid of carbon dioxide waste. Certain lung disease states will affect your lungs’ ability to do so, which contributes to symptoms such as shortness of breath or fatigue.