Effect of Age and Head Position on Total and Regional Aerosol Deposition in Three-Dimensional Models of Human Intranasal Airways Using a Mucosal Atomization Device

Background: This study examined the effect of age and head position on total and regional deposition of aerosol delivered by a mucosal atomization device (MAD™) in three-dimensional (3D) models of the intranasal airways of an 18-, 5-, and 2-year-old human. Models consisted of four pieces: anterior nose and nasal cavity that was divided horizontally into upper, middle, and lower thirds. Methods: Models were tested six times at supine, supine with head backward at 45° (supine45), and sitting with head backward at 45° (sitting45). The MAD delivered saline/fluorescein aerosol into model nostrils, during static airflow. Model pieces were tested for fluorescence using a fluorometer, and deposition calculated as percent fluorescence per piece relative to its reference. Total deposition (four pieces combined) and regional deposition (four pieces separately) were calculated. Results: Age and head position had little effect on total deposition. In contrast, deposition in the upper and middle third supine45 and in the lower third sitting45 was significantly different in the 2-year-old model, compared with the two older models. In addition, some head positions significantly increased deposition in the upper, middle, and lower thirds within each model, compared with other positions. Upper deposition was significantly greater at supine45, compared with sitting45 (18-year-old) and supine45, compared with supine and sitting45 (5-year-old). Middle deposition was significantly greater at supine and supine45, compared with sitting45 (2-year-old). Lower deposition was significantly greater at sitting45, compared with supine45 (18-year-old); supine and sitting45, compared with supine45 (5-year-old); and sitting45, compared with supine45 and supine (2-year-old). Conclusions: Age and head position significantly affected regional deposition of aerosol delivered by the MAD in these 3D models. Such models might be used to study other methods for targeting intranasal regions with aerosolized medications in children and adults.