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. Most asthma medications work by reducing that "twitchiness. Bronchial thermoplasty uses radiofrequency waves to shrink the smooth muscle itself, a new approach to treating asthma symptoms.
This is the first non-drug treatment for asthma, and it's a very promising technology for patients who have been taking all the medications and whose symptoms are still not completely controlled.
National Jewish and New York's Beth Israel Medical Center are two of about 30 medical centers in the U.S. currently offering bronchial thermoplasty, which was approved by the Food and Drug Administration in April. It was developed by Asthmatix Inc. The company was acquired by Boston Scientific Corp. in September and expects more hospitals to offer the procedure in the future.
Since bronchial thermoplasty is so new, few insurers cover it yet. The total cost to patients can range from $12,000 to $18,000. But some people with severe asthma pay that much per year for medications, doctor visits and hospital expenses.
This is an invasive procedure. It has some risks associated with it, mainly lung collapse, bleeding and additional breathing problems, mostly related to the bronchoscope. Patients also must be at least 18 years old to have the procedure. Since there are no nerves inside the airways, bronchial thermoplasty isn't painful. But patients generally do feel worse for a day or two following the treatments—one reason the procedure is divided into three separate treatments. There's a lot of mucous to cough up, and your throat is a little sore from putting the tube down in it.
Afterward, however, their symptoms improve—sometimes dramatically. In a randomized, double-blind controlled study of 297 patients at 30 sites, those treated with the Alair device had a 32% reduction in asthma attacks, an 84% reduction in emergency-room visits and a 66% reduction in school or work days lost due to asthma. Those results continued when the patients were evaluated again two years after the treatment, according to data presented this week at the annual CHEST conference of the American College of Chest Physicians meeting in Vancouver, Canada.
Bronchial thermoplasty is done in three separate treatments, each focusing on different sections of the lungs. With the patient under light sedation, the interventional pulmonologist guides a standard bronchoscope, a long, flexible tube, through the patient's mouth or nose as far as possible down each airway. An attached camera and light allow the physician to view the airway on a video screen. The thermoplasty device, called the Alair System, travels inside the bronchoscope and has an array of electrodes on its tip that extends and expands to contact the airway walls. The electrodes are then heated with radiofrequency energy, shrinking the muscle and creating a larger opening.
Each activation of the device treats less than an inch of airway. The pulmonologist moves the device and activates it again and again along the dozens of bronchial branches. Some patients have been followed for more than four years now and the smooth muscle in the airways does not become thickened again. The muscle is just gone. It does not grow back.
Patients may still need to use their asthma-maintenance medications after the procedure, although many use their rescue inhalers less often and are able to engage in far more strenuous physical activity than before.
Experts do caution that bronchial thermoplasty isn't for patients with mild, occasional asthma—only those who are taking all possible medications and still having symptoms. As of now, the company estimates that about 10% of asthma sufferers are potential candidates. Some asthma sufferers may be too sick to for bronchial thermoplasty. Those with an FEV1 (for Forced Expiratory Volume, a measure of air exhaled per second) of less than 50% of normal aren't considered good candidates. (WSJ, 11/1/2010)
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