New and Emerging Minimally Invasive Techniques for Lung Volume Reduction: Bronchus
The Emphasys Endobronchial Valve consists of a silicone duckbill, one-way valve attached to a nitinol self-expanding stent retainer with silicone seals to occlude the bronchus around the valve (Fig 1). The valve is inserted into the intended segmental or subsegmental bronchus via a delivery housing device over a guidewire placed via a fiberoptic bronchoscope in a manner similar to stent insertion (Fig 2, 3). The bronchoscope should be reinserted to confirm proper positioning before deployment of the valve from the delivery device. Position adjustments or removal (if necessary) can be accomplished with a biopsy forceps.
Animal studies were performed on sheep with the Emphasys Endobronchial Valve, in which 35 valves were inserted in eight sheep. At sacrifice, gross collapse distal to the valves was seen in 83% of the segments with valves inserted.
A phase I human study of valve placement in 10 patients with emphysema has been reported. Mean FEV1 was 0.725 L (range, 0.37 to 1.02 L; 19 to 46% predicted), with a 6-min walk of 340 m (range, 245 to 425 m). Four to 11 valves were inserted per patient under general anesthesia. Symptomatic improvement was noted in four patients. Spirometry and 6-min walk distances were unchanged, but Dlco increased significantly (7.45 ± 2 to 8.25 ± 2.6 mL/ min/mm Hg at 1 month; 11% increase). Inpatient stay ranged from 1 to 8 days. Minor complications included exacerbations of COPD (three patients), hemoptysis, pneumothorax, and left lower lobe pneumonia (one each). This initial study established that the valve could be safely placed in patients with emphysema.
A subsequent pilot study with a second-generation Emphasys Endobronchial Valve has been recently published. Eight patients had severe emphysema that was heterogeneous on CT and V/Q scan with severe dyspnea on exertion despite pulmonaryrehabilitation. Baseline median FEV1 was 0.79 L (23% predicted; range, 18.4 to 35.7% predicted), residual volume (RV) was 6.82 L (272.8% predicted; range, 219 to 321% predicted), and Dlco was 35.6% predicted (range, 24.8 to 51.4% predicted).
Figure 1. Emphasys Endobronchial Valve consisting of a silicone duckbill, one-way valve attached to a nitinol self-expanding stent retainer with silicone seals to occlude the bronchus around the valve.
Figure 2. Emphasys Endobronchial Valve compressed in housing device and advanced over guidewire.
Figure 3. Emphasys Endobronchial Valve deployed by retracting housing and releasing the valve.