10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Pores of Kohn: Forgotten Alveolar Structures and Potential Aerosol Generators?
MICHAEL OLDHAM, Owen Moss, Altria Client Services LLC
Abstract Number: 417 Working Group: Aerosols and Health - Connecting the Dots
Abstract Analysis of aerosols in human and animal exhaled breath has identified numerous compounds from the deep lung, including proteins and surfactant constituents. Some mechanisms like coughing or surfactant/mucus plugs have been proposed to explain the presence of these exhaled deep lung constituents. However, these proposed mechanisms do not explain their presence, during normal breathing. Furthermore, current deterministic and computational fluid dynamic models do not provide insight into the means of generating such aerosols. This work explores the possibility that deep lung aerosols might be generated as a normal function of the opening of pores of Kohn.
Pores of Kohn are between-alveoli channels that have been found in numerous species including humans. Initially, pores of Kohn were thought to provide collateral ventilation to prevent excessive localized alveolar pressure. However, currently they are thought to provide collateral ventilation only under extreme conditions of alveolar duct or terminal bronchiole blockage. Additionally the pores are hypothesized to be fluid filled connections between alveoli, reservoirs for surfactant, portals for macrophage movement, and structures that are initially damaged (during development of emphysema when individual alveoli erode and seem to merge) in empheysema.
We reconsider a possible mechanism by which the pores of Kohn might open under normal breathing conditions. During inhalation alveolar tissue stretches, causing pore diameter to increase in spite of resistance from the surface tension of fluid filling the pore. Pore diameter continues to slowly increase until the meniscus at either end of the pore touch thus forming a thin unstable film. When this film randomly breaks during inspiration, the fluid surface tension now contributes to pore expansion. Furthermore, when the fluid film breaks an aerosol is formed.
The instability in the surfactant film, due to change in diameter of a pore of Kohn, results in opening of the pore following breakage of the film -- which can generate aerosols containing surfactant constituents. To more accurately calculate lung deposition and aerosol generation, pores of Kohn should be integrated into deterministic and computational fluid dynamic models.