Comparison of microparticle transport and deposition in nasal cavity of three different age groups

Objective: The nasal cavity effectively captures the particles present in inhaled air, thereby preventing harmful and toxic pollutants from reaching the lungs. This filtering ability of the nasal cavity can be effectively utilized for targeted nasal drug delivery applications. This study aims to understand the particle deposition patterns in three age groups: neonate, infant, and adult.Materials and methods: The CT scans are built using MIMICS 21.0, followed by CATIA V6 to generate a patient-specific airway model. Fluid flow is simulated using ANSYS FLUENT 2021 R2. Spherical monodisperse microparticles ranging from 2 to 60 µm and a density of 1100 kg/m3 are simulated at steady-state and sedentary inspiration conditions.Results: The highest nasal valve depositions for the neonate are 25% for 20 µm, for infants, 10% for 50 µm, 15% for adults, and 15% for 15 µm. At mid nasal region, deposition of 15% for 20 µm is observed for infant and 8% for neonate and adult nasal cavities at a particle size of 10 and 20 µm, respectively. The highest particle deposition at the olfactory region is about 2.7% for the adult nasal cavity for 20 µm, and it is <1% for neonate and infant nasal cavities.Discussion and conclusions: The study of preferred nasal depositions during natural sedentary breathing conditions is utilized to determine the size that allows medication particles to be targeted to specific nose regions.

Powder aerosol delivery through nasal high-flow system: In vitro feasibility and influence of process conditions

We aimed to obtain fundamental information for potential pulmonary delivery of powder aerosols using a clinically-approved nasal high-flow system (AIRVO), with spray-dried mannitol (SD-Man) being a model powder. Compressed air exiting the AIRVO at set 'dispersion' air flow rates dispersed SD-Man loaded in an Osmohaler^® into a human nasal airway replica (NAR) coupled downstream to a Next Generation Impactor (NGI) running at specific 'inspiratory' flow rates. Increasing the dispersion flow rate from 30 to 60L/min increased powder deposition in the NAR from 50 to 70% of the emitted dose, while decreased the NGI deposition from 50 to 30% of the emitted dose. The inspiratory flow rate did not affect powder deposition in the NAR and NGI. In contrast, as the inspiratory flow rate was increased from 15 to 40L/min, powder recovery, emitted fraction, and fine particle fraction below 5μm (as aerosol performance indices) were increased from 90, 30 and 5% to 97, 45 and 8% of the loaded dose, respectively. The dispersion flow rate did not change the performance indices. Importantly, heating and humidification of dispersion airflow, loaded doses, and nasal cannula sizes did not greatly affect the aerosol characteristics.