About 22 million Americans suffer from asthma, an inflammation of the airways in the lungs that causes coughing, wheezing and shortness of breath. It can range in severity from an occasional annoyance to a chronic, life-threatening condition; exercise, allergies and airborne dust or other irritants can set off attacks.
People with chronic asthma often develop a thickening of the smooth muscle lining the airways. "Not only do you have too much muscle, it's too twitchy. If you have irritants in the airways, they can close down almost to the size of a pinhole," says Serpil Erzurum, a pulmonologist and critical-care physician at the Cleveland Clinic who performs the procedure.