Pulmonary Function Tests (PFT)
What are they and why do I need them?
Chest x-rays and CT scans show if there are any abnormalities affecting the lungs. Pulmonary Function Tests indicate how the lungs are functioning; specifically, are the lungs able to bring enough oxygen into the air sacs and allow the oxygen to get into the blood for use by other vital organs?
PFTs are usually performed in order to follow for the progression of lung disease and are also used to determine if surgery is appropriate. They consist of a battery of measurements and are designed to measure the volumes and flow of air that enter and leave the lungs, as well as how efficiently the gases are able to pass from the air sacs into the blood.
Some of the most common Pulmonary Function Tests are:
Spirometry: the patient breathes in deeply and exhales as fully and forcibly as possible, so the measurement of the lungs’ ventilatory function can be assessed.
Body plethysmography: measures the gas volume of the lung, using changes of pressure that occur during breathing.
Diffusion capacity: the patient breathes in small amounts of carbon monoxide and the test measure how much of this gas gets into the blood. This indicates the ability of the lung to allow oxygen into the blood.
Arterial blood gas measurements: a minute amount of blood is extracted from one of the small arteries in the body (usually in the wrist) in order to analyze the amount of oxygen and carbon dioxide in the blood.
- Oxymetry: also provides a measurement of the oxygen level in the blood using a device (pulse oximeter) placed on the patient's finger for a minute or two.