A spirometer is a medical device used to measure the volume of air inspired and expired by the lungs. It measures ventilation, which is the movement of air into and out of the lungs. A spirometer is the main piece of equipment used for basic Pulmonary Function Tests (PFTs) . It is used to diagnose certain types of lung disease such as asthma, bronchitis, and emphysema. It can also be used to rule out lung diseases, find the cause of shortness of breath, assess the effect of contaminants on lung function, the effect of medication, and evaluate progress for disease treatment. Spirometry is a common office test used to assess how well your lungs work by measuring how much air you inhale, how much you exhale, and how quickly you exhale. The test requires you to breathe into a tube attached to a machine called a spirometer. Before the test, a nurse, a technician, or your doctor will give you specific instructions, and doing the test correctly is necessary for accurate and meaningful results. The test is not painful and is performed by a pulmonary function technician. The results of the test can help diagnose problems like asthma and COPD, or can be done to check lung function before surgery. The test can be done in the doctors office or in a special pulmonary function testing lab. An incentive spirometer is a different type of medical device that helps your lungs expand and get stronger, and it can also help clear your lungs of mucus and other fluids.