The global burden COPD is considerable. In the United States, it is the third most common cause of death and is associated with over $50 billion in annual direct and indirect health-care expenditures (
Why were these valves developed?
For decades, lung volume reduction has been investigated as a mechanical approach to counter-act the physiologic effects of emphysematous hyperinflation. Its goal is to improve lung elastic recoil, respiratory muscle mechanical advantage and efficiency, and ventilation/perfusion matching. The landmark National Emphysema Treatment Trial (NETT), published in 2001 and 2003, demonstrated that in a select patient population (upper lobe-predominant emphysema and low exercise capacity), lung volume reduction surgery (LVRS) lowers mortality and improves QOL and exercise tolerance (
How does bronchoscopic lung volume reduction (BLVR) benefit patients with emphysema?
Valves used for ELVR are removable one-way flow devices placed by flexible bronchoscopy into selected airways supplying emphysematous lung. The valves block air entry but allow the exit of secretions and trapped air. This results in atelectasis of the targeted lobe and a decrease in lung volume.
Which endobronchial valves are available in the United States?
In 2018, two valves were approved by the FDA for bronchoscopic lung volume reduction (BLVR) – the Zephyr® EBV (Pulmonx) ( (Fig 1) and the Spiration® Valve System (Olympus) (IBV) (Fig 2). The Zephyr® EBV is a duckbill-shaped silicone valve mounted within a self-expanding nitinol (nickel titanium alloy) stent. It comes in three sizes for airways with a diameter 4 - 8.5 mm. The Spiration® IBV umbrella-shaped valve is com-posed of six nitinol struts surfaced with polyurethane. Its four sizes accommodate airway diameters 5 - 9 mm.
What’s the evidence behind BLVR?
The Endobronchial Valve for Emphysema Palliation Trial (VENT), the largest valve trial thus far, randomized patients with severe heterogeneous emphysema to receive unilateral Zephyr® valve placement or standard medical care (). Overall improvement in spirometry and dyspnea scores was modest in the valve group. Post-hoc analysis identified an important subgroup of patients with significant clinical benefit, those with a complete fissure. This finding gave guidance to further EBV studies on patients with severe emphysema and absent collateral ventilation (CV).
Identifying a complete fissure on imaging is now used as a surrogate for assessing CV and is an integral part of the initial profiling of patients for EBV therapy (Koster TD, et al. Respiration. 2016;92(3):150).
In the STELVIO trial, 68 patients were randomized to Zephyr ® EBV placement or standard medical care (). Those with EBV placement had significantly improved lung function and exercise capacity. TRANSFORM, a multicenter trial evaluating Zephyr® EBV placement in heterogeneous emphysema, showed similar results ( ).
The IMPACT trial compared patients with homogenous emphysema without CV to standard medical therapy alone. It showed improvement in FEV1, QOL scores, and exercise tolerance in the EBV group. This study affirmed that the absence of CV, rather than the pattern of emphysema, correlates with the clinical benefit from EBV therapy (