Endobronchial Valve for Emphysema Palliation Trial (VENT)

Background: Emphysema, caused primarily by smoking, is characterized by the gradual, irreversible breakdown of tissue and loss of elastic recoil within the lungs, causing them to lose the ability to expel air and efficiently absorb oxygen. As this chronic condition inexorably progresses, the diseased, hyperinflated areas of the lung eventually fill the chest cavity, leaving less and less volume available for the viable lung tissue. Lung volume reduction surgery (LVRS) has been shown to offer relief to patients suffering from emphysema when other treatment options fail. Researchers have continued to refine both technique and patient selection in order to improve outcomes. The objective of lung volume reduction is to eliminate dysfunctional, over-inflated regions of lung. Results similar to surgical removal have been obtained by plication (folding) and stapling without tissue removal. These results suggest that isolation of the dysfunctional lung region can achieve similar results to tissue removal. The paradoxical effect of improving lung function by removing (or isolating) lung tissue demonstrates that breathlessness due to emphysema is a function of mechanical inefficiencies in addition to loss of gas-transfer surface area and other physiological mechanisms. At least in some patients, the mechanical compromise is the primary cause of their pulmonary incapacitation and these patients can benefit by addressing their inability to effectively inhale and exhale. Because LVRS reduces trapped gas, others have speculated that results similar to LVRS could be achieved bronchoscopically by reducing the volume of the hyperinflated regions with, or without, atelectasis. Emphasys has developed a bronchoscopic approach to block inspiratory airflow into targeted, hyperinflated regions of the lung, while permitting exhaled gas to escape. This approach may lead to lung volume reduction and provide some of the clinical benefits of LVRS without the high risks and costs associated with such an invasive surgical procedure. Comparison: The primary object of this study is to assess the safety and efficacy of the Emphasys Endobronchial Valve (EBV) and procedure (with pulmonary rehabilitation) compared to medical management (with pulmonary rehabilitation) in patients with heterogeneous emphysema.