Bronchodilator Reversibility Testing This test may be done to help your health care provider give you a more accurate prognosis or craft your treatment plan. Peak Flow Measurement More than 22 million Americans have been diagnosed with asthma. Find out other facts and figures on this chronic disease. Pulmonary Function Tests Pulmonary function tests measure how well your lungs are functioning and are used to help diagnose certain lung disorders. Oximetry Oximetry is a procedure used to measure the oxygen level—or oxygen saturation—in the blood.