2022 Annual Meeting
Effects of Patient Age on Simulated Aerosol Particle Deposition in the Upper Airways of Pediatric Patients
The majority of inhalable pediatric medicine available is designed for adult airways with dosages scaled down with respect to age, despite there being fundamental differences in the anatomical structure of pediatric airways compared to adult subjects. Thus, there is limited understanding of aerosol behavior and deposition within the airways of pediatric subjects, particularly with respect to the differences in airflow across ages as anatomical features change and develop in this region. In performing these studies, the ability to employ alternatives to in vivo data collection is preferred due to the practical and ethical concerns surrounding pediatric patients. In this project, computational simulations were performed to determine the location and frequency of aerosol deposition in pediatric subjects of different ages to better understand the impacts of patient age on the behavior of inhaled aerosol particles. To address this gap in understanding, three pediatric subjects were studied: a 0.3 year old female, a 5.6 year old female, and a 6.9 year old male. In silico and in vitro studies were used in tandem to model deposition within these subjects. Digital 3-dimensional (3D) geometries of pediatric patients were created from computed tomography (CT) scans of the healthy individuals using the Materialise Mimics package. Computational fluid particle dynamics (CFPD) simulations were run using Ansys FLUENT to provide in silico data over a range of particle sizes from 0.1 to 10 microns and a range of flow rates from 10-120 Lpm. These same studies were performed on in vitro models by first 3D printing the geometries using a Carbon digital light synthesis (DLS) 3D printer and measuring aerosol distributions using a next-generation impactor (NGI). In both sets of experiments, our results show an increase in deposition with increases in particle size and flow rate, both of which appear to be more influential in older patients. Deposition mostly occurred in the upper parts of the airway, typically in the anterior naso-oropharynx and the supraglottis. The NGI study of the 5.6 year old female was run with a particle size of 3 microns and a flow rate of 30 Lpm and largely agreed with the computational results. Future work will involve validating the computational results with in vitro data as well as expanding the study to more subjects of different ages.