Pulmonary function test (PFT), in-office

A pulmonary function test is performed by a doctor specializing in lung diseases. These tests help to diagnose and accurately characterize the function of the lungs. There are two types of PFTs: spirometry and plethysmography. Spirometry is the most common functional test and helps to tell the difference between pulmonary diseases that obstruct the airways (like asthma and COPD/emphysema) versus restrictive lung diseases from many underlying causes. Plethysmography provides information about the amount of air remaining within the lungs after deep exhalation, a value not measurable with spirometry.