McMaster University

McMaster University

Faculty of
Health Sciences

McMaster researchers improve asthma control with procedure

Published: March 28, 2007
Dr. John Miller and Dr.  Gerald Cox
Dr. John Miller (left), associate professor of surgery and head of thoracic surgery at St. Joseph’s Healthcare and Dr. Gerard Cox (right), professor of medicine and a respirologist at the Firestone Institute for Respiratory Health.
Photo credit St. Joseph’s Healthcare.

McMaster physicians have proven that a routine medical procedure can provide an improvement in asthma control.

The study by co-principal investigators Dr. Gerard Cox and Dr. John Miller on bronchial thermoplasty as the first non-drug treatment for asthma, has been published in the prestigious New England Journal of Medicine (NEJM).


Dr. Cox is a professor of medicine and a respirologist at the Firestone Institute for Respiratory Health. Dr. John Miller is an associate professor of surgery and head of thoracic surgery at St. Joseph’s Healthcare Hamilton. 

The publication entitled, "Asthma Control during the Year after Bronchial Thermoplasty", showed that patients treated with bronchial thermoplasty, compared to another group that did not receive the procedure, showed significant positive changes such as: decreases in asthma attacks, increases in days with no asthma symptoms, improvement in quality of life, reduction in using medication, and an improvement in asthma control at one year following the procedure. Asthma affects more than 2 million Canadians.

"These findings are very encouraging and are consistent with earlier trial results on bronchial thermoplasty," explains Dr. Cox. "These results make us hopeful that bronchial thermoplasty may be a new option for asthma patients who have asthma symptoms despite use of current drug therapies."

Bronchial thermoplasty is a minimally invasive procedure that reduces the amount of airway smooth muscle that is responsible for the constriction of airways in asthma patients.  Using a flexible bronchoscope through the nose or the mouth, a routine procedure. physicians treat small to medium sized airways with Bronchial Thermoplasty (BT). The BT device generates radio frequency/thermal energy and reduces areas of underlying smooth muscle in the airways. The procedure is completed in three treatment sessions, each lasting less than one hour, and spaced apart by about three weeks. The procedure, like many other flexible endoscopy procedures, is done under light anesthesia, and the patient returns home the same day.

The objective of the Asthma Intervention Research (AIR) Trial, led by Drs. Cox and Miller as part of a global clinical trial, was to examine the effectiveness and safety of bronchial thermoplasty as a treatment for patients with moderate or severe asthma. The randomized controlled trial included 112 patients between the ages of 18-65 at 11 centers in four countries, and followed these patients for one year after treatment.

Dr. John Miller began limited bronchial thermoplasty procedures several years ago in patients who were scheduled to have lung surgery. "We saw that this particular way of treating the airway had a profound effect on the smooth muscle and not much else," Dr. Miller said. "The amount of smooth muscle is significantly reduced by thermoplasty and we recognized that this procedure might therefore be an appropriate treatment for people with asthma."

"I’m quite pleased to say that our experience suggests that the bronchial thermoplasty procedure is quite well-tolerated, and it holds considerable promise for patients with asthma."

Asthma is a common disease in which the airways in the lung become inflamed, excess airway mucus is produced, and airways narrow when muscles within the airway walls contract. During an asthmatic attack, in response to an asthma trigger such as an allergen or irritant, the airway smooth muscle may contract leading to airway narrowing and breathing difficulties.

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