PNNL

Abstract

The percentages of total airflows over the nasal respiratory and olfactory epithelium of female rabbits were calculated from computational fluid dynamics (CFD) simulations of steady-state inhalation. These airflow calculations, along with nasal airway geometry determinations, are critical parameters for hybrid CFD/physiologically based pharmacokinetic models that describe the nasal dosimetry of water soluble or reactive gases and vapors in rabbits. CFD simulations were based upon 3-dimensional computational meshes derived from magnetic resonance images of 3 adult female NZW rabbits. In the anterior portion of the nose, the maxillary turbinates of rabbits are considerably more complex than comparable regions in rats, mice, monkeys or humans. This leads to a greater surface area to volume ratio in this region and thus, the potential for increased extraction of water soluble or reactive gases and vapors in the anterior portion of the nose compared to many other species. Although there was considerable inter-animal variability in the fine structures of the nasal turbinates and airflows in the anterior portions of the nose, there was remarkable consistency between rabbits in the percentage of total inspired airflows that reached the olfactory epithelium lining the ethmoid turbinate region (~20%). These latter results (airflows reaching the ethmoid turbinate region) were also consistent with previous published estimates for the male F344 rat (19%); both of which are higher than the human (7%). These differences in regional airflows can have significant implications in inter-species extrapolations of nasal dosimetry.