A CFD study of the throat during aerosol drug delivery using heliox and air

Deposition of a series of monodisperse aerosol injections in 70/30 helium/oxygen (Heliox) and air for the larynx and trachea was numerically analyzed with Computational Fluid Dynamics (CFD) software. The CFD mesh was prepared from a cadaver-based throat (female, aged 84). Monosize droplets ranging between 0.25 and 10 μm in droplet radius were used for both Heliox and air simulations. The coupled simulation was performed with the KIVA-3V software for a flow rate of 18 l/min, an approximate adult breathing condition. Flow measurements were validated against previous experimental simulations of this cadaver model. It was found that Heliox and air had highly similar flow structures in the simulated region. Flow measurements such as turbulent kinetic energy and velocity magnitude typically differed by less than 5%. Particle deposition was shown to be affected by these small differences in the carrier gas. The use of Heliox led to less particle deposition for all droplet sizes indicating that Heliox will lead to a reduction of in vivo extrathoracic deposition due to the intrinsic properties of the gas phase. This numerical simulation suggests that a continuous Heliox phase provides a stronger steering force to the discrete phase.