Published in a special European Respiratory Society issue of The Lancet, a procedure that had initially showed primary hope in relieving the symptoms of severe emphysema has failed to repeat its early success in the first randomized trail of airway bypass, and no durable benefit was shown.
At present, 6 million individuals worldwide are affected by emphysema, yet there is no cure and very few treatment options are available. Characterized by the destruction and hyperinflation of the lungs, the disease leaves those who suffer from it unable to get air out of their lungs, making breathing and normal daily activities such as eating, bathing, and walking difficult.
Airway bypass was created to reduce lung inflation and shortness of breath. During the operation surgeons create new passages in the lungs in order to release trapped air, which are supported and reinforced with drug-eluting stents.
A prior feasibility investigation in 35 patients 6 months after airway bypass, reported a considerable reduction in residual volume (RV; the amount of air remaining in the lungs after full exhalation) and improvement in dyspnoea (shortness of breath).
The EASE (Exhale airway stents for emphysema) study was created in order to examine the safety and effectiveness of airway bypass in patients with severe emphysema. 315 patients were enrolled from 38 specialist centers worldwide between October 2006 and April 2009, and randomly assigned to airway bypass (208) or sham procedure (107), and followed for up to 12 months.
Although both groups underwent bronchoscopy, only individuals in the treatment group received the airway bypass operation which involved the placement of up to six stents.
Despite results 1 day after the operation showing a considerable reduction in RV and increased forced vital capacity (FVC: the total amount of air breathed in and forced out the lungs), after one month these effects were no longer detectable. After 6 months, no differences were reported in the FVC and a breathlessness test (Medical Research Council dyspnoea score) between the treatment groups.
During the first six months, at least one respiratory adverse effect was reported by 30 (14.4%) patients given airway bypass in comparison with 12 (11.2%) of those given sham control. The most frequent side effects were exacerbation of chronic obstructive pulmonary disease or pulmonary infections that needed hospitalizations for over 7 days.
Although the researchers tried to explain the disappointing results by suggesting that a mixture of factors may be to blame including passages being created but not stented and mucus causing stent blockages. They do however highlight that the investigation provided valuable lessons that will advise future interventions (especially, that these very ill individuals can tolerate general anaesthesia and a complex bronchoscopy operation), as well as providing a unique model for the conduct of randomized sham controlled investigations on medical devices.
The investigators conclude:
“Despite the acute reduction in regional air trapping with an acceptable safety profile, the EASE trial failed to show sustained long-term effects in patients with severe homogenous emphysema. The future use of airway bypass will require improvement of durability to preserve RV reduction.”
Walter Weder and Erich Russi from Zurich University Hospital, Zurich, Switzerland explains in a comment:
“Technical development in this area should continue, with the aim of prolonging the patency of airway stents. In future trials, the selection of patients needs to be done carefully so that the chances of producing a persistent therapeutic effect are high. For progress to be made, detailed analysis of the EASE trial will be needed, to identify responding populations and to improve procedural methods.”
Written by Grace Rattue