Endobronchial Valves for Severe Emphysema
Endobronchial Valves for Severe Emphysema
Sciurba FC, Ernst A, Herth FJ, et al; VENT Study Research Group
N Engl J Med. 2010;363:1233-1244
Lung hyperinflation and air trapping are typical features of severe and very severe emphysema and are responsible for much of the disease's symptoms, particularly dyspnea on exertion. Pharmacotherapy with current bronchodilators provides some relief; however, for patients with severe hyperinflation, symptoms and disability often persist. One remedy that has been explored is lung volume reduction surgery (LVRS), in which the most diseased and least functional lung regions, typically upper lobe segments, are excised. A prospective controlled trial, NETT (National Emphysema Treatment Trial), found that the overall benefit of LVRS was not significantly greater than that of usual therapy, although defined subgroups had a significant improvement in exercise endurance and survival. Because of its aggressive nature, high perioperative mortality rate, and complications in survivors, LVRS has not been widely adopted. Less invasive methods of reducing hyperinflation are being sought.
In the current trial, Sciurba and colleagues explored the bronchoscopic placement of endobronchial valves (EBVs), aiming to reduce hyperinflation by allowing air to escape but not enter preselected lung regions. They randomly assigned 321 carefully selected patients with severe emphysema in a 2:1 ratio to receive either EBV placement (mean, 3.8 valves per patient) or standard medical care. One year later, FEV1 was a modest 6.8% greater in the intervention group than in the control group (P < .005). The other primary outcome was results on the 6-minute walk test; again, the EBV group experienced an improvement of 5.8% compared with the control group (P < .04). Quality of life, an important secondary outcome, also improved modestly in the EBV group. Safety outcomes included higher frequencies of pneumonia, acute exacerbations of chronic obstructive pulmonary disease, and hemoptysis in the intervention group. Dislodgement of 1 or more valves occurred in 10 patients (4.8%).
Severe emphysema is common, is associated with severe symptoms and disability, entails much utilization of healthcare, and lacks disease-modifying treatments. Since the 1960s, various palliative surgical approaches have been attempted, generally with unacceptable outcomes. EBVs, of which at least 3 types are in development, are the latest such intervention. Depending on the type of EBV, several valves can be placed transbronchoscopically into segmental airways that are preselected by computed tomography showing that they supply hyperinflated lung regions.
Sciurba and colleagues' study raises several questions, including whether EBV placement works. EBVs statistically improved both primary efficacy outcomes (lung function and exercise capacity), but only by degrees that were not considered clinically meaningful. If the goal is to decompress hyperinflated regions, one might expect to see radiologic changes in the treated regions, and these have sometimes been evident. However, one would also expect lung volumes to be reduced, and such changes were minor at best, perhaps explaining why the changes in outcomes were not more dramatic. Persistence of hyperinflation has sometimes been the result of collateral ventilation from adjacent lung regions, bypassing the valves. Therefore, some uncertainty surrounds the efficacy of the EBV placement for emphysema.
What are the study's shortcomings? In an accompanying editorial, Anzueto maintains that medical therapy should have been optimized according to current guidelines before random assignment of patients. Apparently this was not done, and one cannot tell whether patients whose medical therapy was optimal obtained any further benefit from the intervention.
Where does EBV placement now stand in the management of severe emphysema? The relatively small benefits of the procedure do not seem to justify the safety concerns of an invasive procedure in these vulnerable patients, as the editorialist suggests. One hopes that technical advances in the valves and their placement and perhaps the identification of appropriate patient subgroups will tilt the risk-benefit balance in favor of a future procedure to address the problem of hyperinflation in these very symptomatic patients.
Abstract
A Randomized Study of Endobronchial Valves for Advanced Emphysema
Sciurba FC, Ernst A, Herth FJ, et al; VENT Study Research Group
N Engl J Med. 2010;363:1233-1244
Summary
Lung hyperinflation and air trapping are typical features of severe and very severe emphysema and are responsible for much of the disease's symptoms, particularly dyspnea on exertion. Pharmacotherapy with current bronchodilators provides some relief; however, for patients with severe hyperinflation, symptoms and disability often persist. One remedy that has been explored is lung volume reduction surgery (LVRS), in which the most diseased and least functional lung regions, typically upper lobe segments, are excised. A prospective controlled trial, NETT (National Emphysema Treatment Trial), found that the overall benefit of LVRS was not significantly greater than that of usual therapy, although defined subgroups had a significant improvement in exercise endurance and survival. Because of its aggressive nature, high perioperative mortality rate, and complications in survivors, LVRS has not been widely adopted. Less invasive methods of reducing hyperinflation are being sought.
In the current trial, Sciurba and colleagues explored the bronchoscopic placement of endobronchial valves (EBVs), aiming to reduce hyperinflation by allowing air to escape but not enter preselected lung regions. They randomly assigned 321 carefully selected patients with severe emphysema in a 2:1 ratio to receive either EBV placement (mean, 3.8 valves per patient) or standard medical care. One year later, FEV1 was a modest 6.8% greater in the intervention group than in the control group (P < .005). The other primary outcome was results on the 6-minute walk test; again, the EBV group experienced an improvement of 5.8% compared with the control group (P < .04). Quality of life, an important secondary outcome, also improved modestly in the EBV group. Safety outcomes included higher frequencies of pneumonia, acute exacerbations of chronic obstructive pulmonary disease, and hemoptysis in the intervention group. Dislodgement of 1 or more valves occurred in 10 patients (4.8%).
Viewpoint
Severe emphysema is common, is associated with severe symptoms and disability, entails much utilization of healthcare, and lacks disease-modifying treatments. Since the 1960s, various palliative surgical approaches have been attempted, generally with unacceptable outcomes. EBVs, of which at least 3 types are in development, are the latest such intervention. Depending on the type of EBV, several valves can be placed transbronchoscopically into segmental airways that are preselected by computed tomography showing that they supply hyperinflated lung regions.
Sciurba and colleagues' study raises several questions, including whether EBV placement works. EBVs statistically improved both primary efficacy outcomes (lung function and exercise capacity), but only by degrees that were not considered clinically meaningful. If the goal is to decompress hyperinflated regions, one might expect to see radiologic changes in the treated regions, and these have sometimes been evident. However, one would also expect lung volumes to be reduced, and such changes were minor at best, perhaps explaining why the changes in outcomes were not more dramatic. Persistence of hyperinflation has sometimes been the result of collateral ventilation from adjacent lung regions, bypassing the valves. Therefore, some uncertainty surrounds the efficacy of the EBV placement for emphysema.
What are the study's shortcomings? In an accompanying editorial, Anzueto maintains that medical therapy should have been optimized according to current guidelines before random assignment of patients. Apparently this was not done, and one cannot tell whether patients whose medical therapy was optimal obtained any further benefit from the intervention.
Where does EBV placement now stand in the management of severe emphysema? The relatively small benefits of the procedure do not seem to justify the safety concerns of an invasive procedure in these vulnerable patients, as the editorialist suggests. One hopes that technical advances in the valves and their placement and perhaps the identification of appropriate patient subgroups will tilt the risk-benefit balance in favor of a future procedure to address the problem of hyperinflation in these very symptomatic patients.
Abstract
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