Pulmonary Function Tests (PFTs) are a group of noninvasive diagnostic tests that provide your doctor with feedback about the function of your lungs. PFTs measure how well your lungs take in and release air and how well they move oxygen from the atmosphere into your circulation. For some of the tests, you can breathe normally, while others will require forced inhalation or exhalation. Pulmonary Function Tests are performed to diagnose certain types of lung disease, find the cause of shortness of breath, assess the effect of medication, and measure progress in disease treatment.