A Computational Study of Nasal Spray Deposition Pattern in Four Ethnic Groups.
BACKGROUND
Very little is known about the role of nasal morphology due to ethnic variation on particle deposition pattern in the sinonasal cavity. This preliminary study utilizes computational fluid dynamics (CFD) modeling to investigate sinonasal airway morphology and deposition patterns of intranasal sprayed particles in the nose and sinuses of individuals from four different ethnic groups: African American (Black); Asian; Caucasian; and Latin American.


METHODS
Sixteen subjects (four from each ethnic group) with "normal" sinus protocol computed tomography (CT) were selected for CFD analysis. Three-dimensional reconstruction of each subject's sinonasal cavity was created from their personal CT images. CFD simulations were carried out in ANSYS Fluent(™) in two phases: airflow phase was done by numerically solving the Navier-Stokes equations for steady state laminar inhalation; and particle dispersed phase was solved by tracking injected (sprayed) particles through the calculated airflow field. A total of 10,000 particle streams were released from each nostril, 1000 particles per diameter ranging from 5 μm to 50 μm, with size increments of 5 μm.


RESULTS
As reported in the literature, Caucasians (5.31 ± 0.42 cm(-1)) and Latin Americans (5.16 ± 0.40cm(-1)) had the highest surface area to volume ratio, while African Americans had highest nasal index (95.91 ± 2.22). Nasal resistance (NR) was highest among Caucasians (0.046 ± 0.008 Pa.s/mL) and Asians (0.042 ± 0.016Pa.s/mL). Asians and African Americans had the most regions with particle deposition for small (5 μm-15 μm) and large (20 μm-50 μm) particle sizes, respectively. Asians and Latin Americans individuals had the most consistent regional particle deposition pattern in the main nasal cavities within their respective ethnic groups.


CONCLUSIONS
Preliminary results from these ethnic groups investigated showed that Caucasians and Latin Americans had the least patent nasal cavity. Furthermore, Caucasians and African Americans had the lowest inter-subject consistency in regional particle deposition pattern; this may be due to greater inter-subject variability in their respective nasal vestibule morphology.
Division of Otolaryngology, Head and Neck Surgery, Duke University Medical Center , Durham, North Carolina.
Jarrod A
JA
Keeler
Division of Otolaryngology, Head and Neck Surgery, Duke University Medical Center , Durham, North Carolina.
Aniruddha
A
Patki
Division of Otolaryngology, Head and Neck Surgery, Duke University Medical Center , Durham, North Carolina.
Charles R
CR
Woodard
Division of Otolaryngology, Head and Neck Surgery, Duke University Medical Center , Durham, North Carolina.
Dennis O
DO
Frank-Ito
D000280:Administration, Inhalation; D000336:Aerosols; D001741:Black or African American; D000403:Airway Resistance; D001213:Asian; D003198:Computer Simulation; D005006:Ethnicity; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D057446:Hydrodynamics; D021621:Imaging, Three-Dimensional; D008297:Male; D008953:Models, Anatomic; D009296:Nasal Cavity / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D009716:Numerical Analysis, Computer-Assisted; D010256:Paranasal Sinuses / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology; D010316:Particle Size; D004364:Pharmaceutical Preparations / Q000008:administration & dosage*; D011857:Radiographic Image Interpretation, Computer-Assisted; D012119:Respiration; D036542:Tomography, Spiral Computed; D044465:White People
D000336:Aerosols; D004364:Pharmaceutical Preparations
African American; Asian; Caucasian; Latin American; computational fluid dynamics; nasal morphology; nasal resistance; nasal spray; particle deposition