Airway Bypass Improves the Mechanical Properties of Explanted Emphysematous Lungs

Rationale: By creating artificial communications through bronchial walls into the parenchyma of explanted lungs (airway bypass), we expect to decrease the amount of gas trapped and to increase the rate and volume of air expelled during forced expirations. Objectives: To describe the mechanism by which airway bypass improves the mechanical properties of the emphysematous lung. Methods: Lung compartments and mechanics were measured before and after airway bypass, which was created by placement of three or four stent-suppported fenestrations in 10 emphysematous lungs removed at transplantation surgery. Measurements and Main Results: Minimal volume after passive deflation decreased by a mean of 1.54 L (range, 0.7-2.5 L) or 60% (range, 37-86%). Explanted VC increased by 1.30 L or 132% (range, 78-318%). Maximal expiratory flows and volumes increased. Flow resistance decreased. Conclusions: Because these data show that airway bypass improves the mechanics of breathing in severely emphysematous lungs in vitro, there is now strong empirical support that this procedure can improve ventilatory function in patients by reducing gas trapping and flow resistance.