Removing Lung Tissue Alleviates Asthma

In a study by researchers at the McMaster University Firestone Institute for Respiratory Health (Hamilton, Ontario, Canada), 16 patients underwent bronchial thermoplasty (BT), a procedure that reduces the potential for smooth muscle-mediated bronchoconstriction by reducing the mass of smooth muscle in the walls of conducting airways. Baseline and 12-week post-treatment measurements included spirometry, methacholine challenge, and daily diary recordings of peak flow, symptoms, and medication usage. Subjects completed follow-up evaluations at 12 weeks, one year, and two years.

Results showed the procedure was well tolerated and side effects were transient and typical of what is commonly observed after bronchoscopy. All subjects demonstrated improvement in airway responsiveness. Data from daily diaries collected for 12 weeks indicated significant improvements over baseline in symptom-free days, morning peak flow, and evening peak flow. Spirometry measurements remained stable throughout the study period. The results were published in the May 1, 2006, issue of the American Journal of Respiratory and Critical Care Medicine.

"The procedure was well tolerated,” said lead author Dr. Gerard Cox, a respirologist at Firestone and a division director within the department of medicine at McMaster University. "Side effects were transient and typical of what is commonly observed after bronchoscopy. All subjects also demonstrated improvement in airway responsiveness.”

Bronchial thermoplasty involves threading a bronchoscope through the nose or throat of the patient and into the airways that fill the lungs. A wire basket on the tip is inflated to touch the airway walls, and radiofrequency (RF) waves are beamed through those wires. The RF waves beam through the airway's thin lining without scarring it, while heating smooth muscle underneath to about 65oC, a temperature high enough to reduce airway smooth muscle mass but low enough to avoid tissue destruction and scarring.


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