['The crippling effects of emphysema are due in part to dynamic hyperinflation, resulting in altered respiratory mechanics, an increased work of breathing, and a pervasive sense of dyspnea. Because of the extensive collateral ventilation present in emphysematous lungs, we hypothesize that placement of stents between pulmonary parenchyma and large airways could effectively improve expiratory flow, thus reducing dynamic hyperinflation.', 'Twelve human emphysematous lungs, removed at the time of lung transplantation, were placed in an airtight ventilation chamber with the bronchus attached to a tube traversing the chamber wall, and attached to a pneumotachometer. The chamber was evacuated to -10 cm H2O pressure for lung inflation. A forced expiratory maneuver was simulated by rapidly pressurizing the chamber to 20 cm H2O, while the expiratory volume was continuously recorded. A flexible bronchoscope was then inserted into the airway and a radiofrequency catheter (Broncus Technologies) was used to create a passage through the wall of three separate segmental bronchi into the adjacent lung parenchyma. An expandable stent, 1.5 cm in length and 3 mm in diameter, was then inserted through each passage. Expiratory volumes were then remeasured as above. In six experiments, two additional stents were then inserted and forced expiratory volumes again determined.', 'The forced expiratory volume in 1 second (FEV1) increased from 245 +/- 107 mL at baseline to 447 +/- 199 mL after placement of three bronchopulmonary stents (p < 0.001). With two additional stents, the FEV1 increased to 666 +/- 284 mL (p < 0.001).'] Does bronchial fenestration improve expiratory flow in emphysematous human lungs?