The studies included in this review were few in number and suffered from methodological shortcomings, which means that rigorous conclusions cannot be drawn about the effectiveness and safety of endobronchial valves in the treatment of diffuse heterogeneous-type emphysema. Treatment of this disease using endobronchial duckbill valves is associated with a significantly higher number of adverse effects and rehospitalizations than those observed for the control group. Reports of the preliminary results of the VENT study do not reflect overall clinically significant improvements among patients with diffuse heterogeneous-type emphysema. The procedure appears to display differing efficacy in line with patients' baseline status and the treatment strategy to be used. The current dearth of studies renders it impossible for conclusions to be drawn about endobronchial umbrella valves.
