Pulmonary function test: A test that is designed to measure how well the lungs are working. Abbreviated PFT. Pulmonary Function Test gauges how the lungs are expanding and contracting (when a person inhales and exhales) and measures the efficiency of the exchange of oxygen and carbon dioxide between the blood and the air within the lungs.
Pulmonary function testing is a diagnostic and management tool used for a variety of reasons, such as:
·         Chronic shortness of breath
·         Asthma
·         Chronic obstructive pulmonary disease
·         Restrictive lung disease
·         Preoperative testing
·         Impairment or disability

Spirometry includes tests of pulmonary mechanics – measurements of FVC, FEV1, FEF values, forced inspiratory flow rates (FIFs), and MVV. Measuring pulmonary mechanics assesses the ability of the lungs to move huge volumes of air quickly through the airways to identify airway obstruction.
The measurements taken by the spirometry device are used to generate a pneumotachograph that can help to assess lung conditions such as: asthma, pulmonary fibrosis, cystic fibrosis, and chronic obstructive pulmonary disease. Physicians may also use the test results to diagnose bronchial hyperresponsiveness to exercise, cold air, or pharmaceutical agents.