Transpleural ventilation of explanted human lungs

Cliff K. Choong ¹, Peter T. Macklem ², John A. Pierce ^3*, Stephen S. Lefrak ³, Jason C. Woods ³, Mark S. Conradi ³, Dimitry A. Yablonskiy ⁴, James C. Hogg ⁵, Kimiaki Chino ⁶ and Joel D. Cooper ³

¹ Papworth Hospital, United Kingdom
² McGill University Health Centre Research Institute, Canada
³ Washington University School of Medicine, United States
⁴ Washington University, United States
⁵ University of British Columbia, Canada
⁶ Tokyo Women's Medical University, Japan

^* To whom correspondence should be addressed. E-mail: john.a.pierce{at}sbcglobal.net.

Accepted 8 December 2006

Abstract

We tested the hypothesis that ventilation of emphysema lungs would be enhanced by communications with the parenchyma through holes in the pleural surface. 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: 1) flow-volume-time curves during passive deflation via each pathway; 2) volume of trapped gas recovered from lungs via spiracles when no additional gas was obtainable passively from the airways; and 3) magnetic resonance imaging assessment of spatial distribution of hyperpolarized helium (3He) administered through either the airways or spiracles. In emphysema lungs, 1) passively expelled volumes at 20 seconds were 94% greater through spiracles than via airways; 2) following passive deflation from the airways, an average of 1.07 L of trapped gas volume was recoverable via spiracles; and 3) regions were ventilated by spiracles that were less well ventilated via bronchi. Because of the extensive collateral ventilation present in the emphysematous lungs, direct communication with lung parenchyma through nonanatomic pathways has potential to improve the mechanics of breathing, and hence ventilation.

Keywords: collateral ventilation, hyperpolarized He imaging in emphysema, lung mechanics, pulmonary emphysema, transpleural ventilation

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