Pulmonary Function Tests (PFTs)

Pulmonary function tests (PFTs) are 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 environment into the body's circulation.

Types of Pulmonary Function Tests

• Spirometry: This is the most common type of PFT. It measures how much air a person can inhale and exhale, and how quickly they can do it.
• Plethysmography: This test measures the total amount of air in the lungs, including the air that remains after a full exhalation.
• Diffusing capacity of the lungs for carbon monoxide (DLCO): This test measures how well the lungs transfer oxygen from the air into the bloodstream.
• Body plethysmography: This test measures the total lung volume and can help diagnose conditions such as chronic obstructive pulmonary disease (COPD).
• Nitrogen washout test: This test measures how well the lungs remove nitrogen from the air.
• Exercise stress test: This test measures how well the lungs function during exercise.

How Pulmonary Function Tests are Performed

PFTs are typically performed in a doctor's office or hospital. The tests may be done at rest or during exercise, and may involve breathing into a tube or wearing a mask over the nose and mouth.

• The patient will be asked to breathe in and out of a spirometer, which measures the amount and speed of air breathed in and out.
• The patient may be asked to hold their breath for a few seconds to allow the lungs to fill with air.
• The patient may be asked to breathe in a special gas, such as helium or oxygen, to help measure lung function.

What Pulmonary Function Tests Measure

PFTs measure several different aspects of lung function, including:

• Forced vital capacity (FVC): The total amount of air that can be exhaled from the lungs after a maximum inhalation.
• Forced expiratory volume in one second (FEV1): The amount of air that can be exhaled from the lungs in one second.
• Peak expiratory flow (PEF): The fastest rate at which a person can exhale air.
• Total lung capacity (TLC): The total amount of air in the lungs after a maximum inhalation.
• Residual volume (RV): The amount of air that remains in the lungs after a maximum exhalation.

What Pulmonary Function Tests are Used For

PFTs are used to diagnose and monitor a wide range of lung conditions, including:

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Cystic fibrosis
• Pneumonia
• Pulmonary embolism
• Sarcoidosis
• Tuberculosis

Risks and Limitations of Pulmonary Function Tests

While PFTs are generally safe, there are some risks and limitations to consider:

• PFTs may not be accurate in people with certain medical conditions, such as a history of lung surgery or a pacemaker.
• PFTs may cause shortness of breath or discomfort in people with underlying lung disease.
• PFTs may not diagnose all types of lung disease, and additional tests may be needed to confirm a diagnosis.