Pulmonary function test
A test designed to measure how well the lungs are working.
Pulmonary function tests (PFTs) gauge how the lungs are carrying out their tasks -- of expanding and contracting (when a person inhales and exhales) and of exchanging oxygen and carbon dioxide efficiently between the air (or other gases) within the lungs and the blood.
For example, one pulmonary function test calls for the patient to breathe into a machine called a spirometer.
It is a mechanical device that records the changes in lung size as air is inhaled and exhaled and the time it takes for the patient to do this task.