Subject-variability effects on micron particle deposition in human nasal cavities

Abstract

A B S T R A C TValidated computer simulations of the airflow and particle dynamics in human nasal cavities are important for local, segmental and total deposition predictions of both inhaled toxic and therapeutic particles. Considering three, quite different subject-specific nasal airway configurations, micron-particle transport and deposition for low-to-medium flow rates have been analyzed. Of special interest was the olfactory region from which deposited drugs could readily migrate to the central nervous system for effective treatment. A secondary objective was the development of a new dimensionless group with which total particle deposition efficiency curves are very similar for all airway models, i.e., greatly reducing the impact of intersubject variability. Assuming dilute particle suspensions with inhalation flow rates ranging from 7.5 to 20 L/min, the airflow and particle-trajectory equations were solved in parallel with the in-house, multi-purpose Alya program at the Barcelona Supercomputing Center. The geometrically complex nasal airways generated intriguing airflow fields where the three subject models exhibit among them both similar as well as diverse flow structures and wall shear stress distributions, all related to the coupled particle transport and deposition. Nevertheless, with the new Stokes-Reynolds-number group, Stk Re 1.23 1.28 , the total deposition-efficiency curves for all three subjects and flow rates almost collapsed to a single function. However, local particle deposition efficiencies differed significantly for the three subjects when using particle diameters d p = 2, 10, and m 20 μ . Only one of the three subject-specific olfactory regions received, at relatively high values of the inertial parameter d Q p 2 , some inhaled microspheres. Clearly, for drug delivery to the brain via the olfactory region, a new method of directional inhalation of nanoparticles would have to be implemented.

Size, composition, morphology, and health implications of airborne incidental metal-containing nanoparticles

“…(55) This is of particular importance as the olfactory route is one of the proposed mechanisms for nanoparticle translocation to the brain. (36) Despite that in the studies modeling nasal deposition only a few micron-sized particles deposit on the olfactory region, (56) the NP-collectors could play an important role in nanoparticles translocation to the brain as their surface is enriched with multiple INPs. In addition, the translocation is expected to only occur for individual or a few nanoparticles agglomerates; which in both cases implies a de-agglomeration process.…”

A novel method to generate dynamic boundary conditions for airway CFD by mapping upper airway movement with non‐rigid registration of dynamic and static MRI

“…Computational fluid dynamics (CFD) simulations have been widely used to provide information about human airways, including airway resistance, energy expended during breathing (work of breathing), distribution of airflow, transfer of heat and moisture, and particle deposition . Other methods are unable to provide this level of information due to the impracticalities of using flow instrumentation in the airway.…”

“…Computational fluid dynamics (CFD) simulations have been widely used to provide information about human airways, including airway resistance, energy expended during breathing (work of breathing), distribution of airflow, transfer of heat and moisture, and particle deposition. [1][2][3][4][5][6] Other methods are unable to provide this level of information due to the impracticalities of using flow instrumentation in the airway. The metrics provided by CFD are becoming increasingly useful clinically and have been used to assess the effort of breathing in goiters [7][8][9] in transplanted tracheas, 10 stenotic pediatric tracheas, 11 and nasal obstruction.…”

A Review of Respiratory Anatomical Development, Air Flow Characterization and Particle Deposition

“…A variety of studies [45,58,106] has been conducted to predict the aerosol particle deposition in the extrathoracic region of the human lung using idealized anatomical models of circular or elliptic or constant diameter [107,108]. Recently, realistic CT/MRI based [109][110][111] anatomical models have been used to predict the local deposition in the extrathoracic airways. Xi and Longest [62] conducted a comparative study for local deposition in the mouth throat to larynx for different anatomical (realistic, circular, elliptic, fixed diameter) models and concluded that the CT-based realistic model provided the most accurate prediction of the experimental measurements.…”