Exploring E-Vape Aerosol Penetration into Paranasal Sinuses: Insights from Patient-Specific Models

Background: Acute and chronic sinusitis significantly impact patients' quality of life. Effective drug delivery to paranasal sinuses is crucial for treating these conditions. However, medications from conventional devices like nasal drops, sprays, and nebulized mists often fail to penetrate the small ostia and reach the sinuses. This study aims to assess the effectiveness of e-vape-generated aerosols entering and filling paranasal sinus cavities, particularly the maxillary sinus. Methods: The aerosol droplets were generated using an electronic vaporizer (e-vape) and were composed solely of vegetable glycerin (VG) and propylene glycol (PG). Patient-specific, transparent nose-sinus models, including one with post-uncinectomy surgery, were used to evaluate the effectiveness of these e-vape-generated VG-PG aerosols in entering the sinuses under unidirectional and bidirectional airflow conditions. Visualizations from various nasal model views and lighting conditions were recorded. Particle size distribution measurements of the e-vape aerosol were conducted using a laser diffraction particle size analyzer. Results: E-vape-generated VG-PG droplets effectively enter paranasal sinuses under specific administration conditions. E-vape aerosol droplet size measurements revealed a mean particle size ranging from 2.895 to 3.359 μm, with a median particle size (D50) averaging 2.963 μm. The speed of aerosol entering the paranasal sinuses is directly proportional to the ostia size; larger ostia result in faster sinus entry. A continuous moderate flow is necessary to gradually fill the paranasal sinus cavities. The aerosol entry into sinuses was observed at 2 L/min and decreased with increasing flow rate. The mechanisms of aerosol entry involve maintaining a positive pressure gradient across the ostial canal, a non-equilibrium transverse pressure distribution, and a two-way flow through the ostium. Gravitational forces and recirculation currents further enhance the deposition of e-vape aerosols. Comparative tests showed that traditional delivery devices exhibited limited penetration into paranasal sinuses. Conclusions: This study demonstrated that e-vape-generated aerosols could serve as a vehicle for delivering active pharmaceutical ingredients (APIs) directly to the paranasal sinuses, improving treatment outcomes.