Design of the Endobronchial Valve for Emphysema Palliation Trial (VENT): a non-surgical method of lung volume reduction

Abstract

Background: Lung volume reduction surgery is effective at improving lung function, quality of life, and mortality in carefully selected individuals with advanced emphysema. Recently, less invasive bronchoscopic approaches have been designed to utilize these principles while avoiding the associated perioperative risks. The Endobronchial Valve for Emphysema PalliatioN Trial (VENT) posits that occlusion of a single pulmonary lobe through bronchoscopically placed Zephyr endobronchial valves will effect significant improvements in lung function and exercise tolerance with an acceptable risk profile in advanced emphysema.

Methods: The trial design posted on Clinical trials.gov, on August 10, 2005 proposed an enrollment of 270 subjects. Inclusion criteria included: diagnosis of emphysema with forced expiratory volume in one second (FEV1) < 45% of predicted, hyperinflation (total lung capacity measured by body plethysmography > 100%; residual volume > 150% predicted), and heterogeneous emphysema defined using a quantitative chest computed tomography algorithm. Following standardized pulmonary rehabilitation, patients were randomized 2:1 to receive unilateral lobar placement of endobronchial valves plus optimal medical management or optimal medical management alone. The co-primary endpoint was the mean percent change in FEV1 and six minute walk distance at 180 days. Secondary end-points included mean percent change in St. George's Respiratory Questionnaire score and the mean absolute changes in the maximal work load measured by cycle ergometry, dyspnea (mMRC) score, and total oxygen use per day. Per patient response rates in clinically significant improvement/maintenance of FEV1 and six minute walk distance and technical success rates of valve placement were recorded. Apriori response predictors based on quantitative CT and lung physiology were defined.

Conclusion: If endobronchial valves improve FEV1 and health status with an acceptable safety profile in advanced emphysema, they would offer a novel intervention for this progressive and debilitating disease.

Trial registration: ClinicalTrials.gov: NCT00129584.

Figure 1

Zephyr^® Endobronchial Valve side view.

Figure 2

Implanted Zephyr^® Endobronchial Valve end view. The Zephyr^® Endobronchial Valve vents during expiration (left) and seals during inspiration (right) immediately after placement.

Figure 3

Lobar treatment targeting algorithm. A single lobe for treatment is selected by determining the highest emphysema score (ES). If emphysema scores are identical between lobes on both lungs, then the lung with the most heterogeneity is selected. The heterogeneity score (HS) is derived by subtracting the best lobe score from the worst lobe score in a single lung. If both lungs are equally affected with emphysema and heterogeneity, the computer generated absolute % density score (DS) is used to select the most affected lobe for targeting.