Transpleural ventilation of explanted human lungs

Background: The hypothesis that ventilation of emphysematous lungs would be enhanced by communication with the parenchyma through holes in the pleural surface was tested. Methods: Fresh human lungs were obtained from patients with emphysema undergoing lung transplantation. Control human lungs were obtained from organ donors whose lungs, for technical reasons, were not considered suitable for implantation. Lungs were ventilated through the bronchial tree or transpleurally via a small hole communicating with the underlying parenchyma over which a flanged silicone tube had been cemented to the surface of the lung (spiracle). Measurements included flow-volume-time curves during passive deflation via each pathway; volume of trapped gas recovered from lungs via spiracles when no additional gas was obtainable passively from the airways; and magnetic resonance imaging assessment of spatial distribution of hyperpolarised helium (He-3) administered through either the airways or spiracles. Results: In emphysematous lungs, passively expelled volumes at 20 s were 94% greater through spiracles than via the airways. Following passive deflation from the airways, an average of 1.07 litres of trapped gas volume was recoverable via spiracles. Regions were ventilated by spiracles that were less well ventilated via bronchi. Conclusions: Because of the extensive collateral ventilation present in emphysematous lungs, direct communication with the lung parenchyma through non-anatomical pathways has the potential to improve the mechanics of breathing and hence ventilation.