A pulmonary function test, or PFT, is a series of three separate tests. Each test tells the provider something different about how your lungs are working. You will be asked to perform several different breathing maneuvers while breathing in and out through a mouthpiece. A Respiratory Therapist will guide you through the whole process and ensure that the provider gets the information they need. You may find some of the maneuvers challenging, but PFTs give the provider a lot of information and are extremely helpful in diagnosing and managing lung disease.