Pulmonary function tests are a diagnostic method used to objectively measure the capacity and functional status of the lungs, using devices called 'spirometers'. Rules to be considered before the test The case is informed about the test. Smoking history, past illnesses, and medications used are recorded. No smoking for 24 hours before the test, no alcohol for 4 hours, no heavy exercise 30 minutes before, no heavy meals 2 hours before, no short-acting bronchodilator drugs 4 hours before, no long-acting bronchodilators before 12 hours. Clothing that restricts chest and abdominal movements should not be worn.