Analysis of particle deposition in the turbinate and olfactory regions using a human nasal computational fluid dynamics model.

The human nasal passages effectively filter particles from inhaled air. This prevents harmful pollutants from reaching susceptible pulmonary airways, but may leave the nasal mucosa vulnerable to potentially injurious effects from inhaled toxicants. This filtering property may also be strategically used for aerosolized nasal drug delivery. The nasal route has recently been considered as a means of delivering systemically acting drugs due to the large absorptive surface area available in close proximity to the nostrils. In this study, a computational fluid dynamics (CFD) model of nasal airflow was used with a particle transport and deposition code to predict localized deposition of inhaled particles in human nasal passages. The model geometry was formed from MRI scan tracings of the nasal passages of a healthy adult male. Spherical particles ranging in size from 5 to 50 microm were released from the nostrils. Particle trajectories and deposition sites were calculated in the presence of steady-state inspiratory airflow at volumetric flow rates of 7.5, 15, and 30 L/min. The nasal valve, turbinates, and olfactory region were defined in the CFD model so that particles depositing in these regions could be identified and correlated with their release positions on the nostril surfaces. When plotted against impaction parameter, deposition efficiencies in these regions exhibited maximum values of 53%, 20%, and 3%, respectively. Analysis of preferential deposition patterns and nostril release positions under natural breathing scenarios can be used to determine optimal particle size and flow rate combinations to selectively target drug particles to specific regions of the nose.