Chaotic Mixing of Aerosol in Rhythmically Expanding Lung


Principal Investigator:
Akira Tsuda, Principal Research Scientist in Physiology


Dates of Research:
August 1, 2005 — July 31, 2010


Inhaled particles play a major role in inducing or exacerbating respiratory diseases. The acinar region, with its enormously large surface area and very thin and delicate blood/gas barrier, is particularly vulnerable to the damaging effects of depositing particles. An essential step in understanding toxic particle exposure-associated processes in the pulmonary acinus, as well as targeted drug delivery by aerosol inhalation is to characterize deposition and to elucidate the mechanisms involved. Previously a framework for acinar deposition established that acinar gas flow can be kinematically irreversible, and that chaotic mixing, manifested by stretching and folding patterns, can be a major contributor to aerosol deposition. This project aims to study the specific mechanisms of the stretch and fold kinematics. Our main hypothesis is that tidal air front evolves into an enormously stretched layer upon inhalation which drapes the inner surface of the acinar airways, thus brining airborne aerosols very close to the alveolar septal surface and promoting their deposition. During inhalation, folding of the previously stretched layer leads to lateral transport of aerosols, also significantly contributing to the deposition process.