(316d) Aerosol Therapeutic Delivery in 3D Printed Pediatric Airway Replicas

The current standard method of characterizing aerosol delivery variations between adult and pediatric patients uses idealized throat models in conjunction with a Next Generation Impactor (NGI). The standard pediatric idealized throat groups together children of all ages, neglects variations as the lungs develop, and was modeled based on an adult throat; namely the Alberta Idealized Throat (AIT). There is limited information on aerosol delivery dependency for each age and patient geometry, mostly due to small sample sizes. Advances in 3D printing allow us to develop throat models based on 60 patient computed tomography (CT) scans from healthy pediatric subjects. A Collison jet nebulizer and a PARI Vios Pediatric nebulizer were used in-line with the pharmaceutical standard aerosol characterizing equipment, a Next Generation Impactor (NGI), to quantify deposition profiles variations for patients and the AIT. Results indicate that there are significant differences in particle deposition and mass mean aerodynamic diameter between the IP and the pediatric model for a range of particle sizes tested at 30 L/min. Larger particles deposit in the throat and result in a shift in the particles that are delivered to the lungs for pediatric patients. There is a shift in mass fraction from 0.18 to 0.41, n=3 and p=0.003, of 1 µm particles delivered to the lungs when using a pediatric replica. The underestimation of mass fraction delivered to pediatric patients suggests the possible overestimation of required dosing when developing pharmaceuticals. Additionally, throat deposition of 3 – 6 µm particles indicates that the current fine particle fraction standard is not representative for pediatric patients. Information from trends in delivery based on age and patient geometry will lead to improved fundamental knowledge of pediatric aerosol delivery and guidelines for pharmaceutical development.