Spirometry is a test used to assess respiratory disease by determining how much air the lungs can hold as well as how much and how quickly air can be exhaled. The test is done with a spirometer, which consists of a mouthpiece and tubing connected to a recording device. A person inhales deeply, then exhales vigorously and as quickly as possible through the tubing while measurements are taken. The volume of air inhaled or exhaled and the length of time each breath takes are recorded and analyzed. Often, the tests are repeated after a person takes a drug that opens the airways of the lungs (a bronchodilator).