Nasal steroid spray simulations using measured spray characteristics in healthy and rhinitic nasal passages

Abstract

Intranasal corticosteroid sprays (ICSs) are frequently prescribed for allergic rhinitis (AR), which is the fifth most common chronic disease in the United States. This study aimed to investigate how the intranasal distribution of ICSs is affected by spray characteristics, patient use factors, and anatomical variation. Three-dimensional reconstructions of the nasal cavity were created from computed tomography (CT) scans of one healthy subject and one AR patient. A virtual spray nozzle was positioned in the nasal vestibule according to package insert instructions and subtracted from the nasal airspace. Hybrid tetrahedral-prism meshes were created and spray simulations were conducted in ANSYS Fluent™ with inspiratory airflow present and spray characteristics from in vitro experiments. Changes in regional corticosteroid deposition with variations in spray product, actuation force, inhalation rate, spray cone angle, nozzle insertion depth, nozzle position, and nasal side were assessed. The simulation results demonstrated that, in both models, target site deposition was mostly affected by changes in nozzle position and anatomy (left vs. right nostril). In the healthy subject, target site deposition increased with a higher actuation force, higher inhalation rate, and smaller nozzle depth, but was not significantly affected by changes in the spray cone angle. In the AR patient, target site deposition was not significantly different for changes in actuation force, inhalation rate, nozzle depth, or cone angle. The findings of this numerical study suggest that the intranasal distribution of ICSs is influenced mostly by nozzle position and nasal anatomy.