Deposition simulations of realistic dosages in patient-specific airways with two- and four-way coupling

TL;DR

This study uses advanced simulations to analyze how particle-fluid interactions affect drug deposition in patient-specific airways, highlighting the importance of two- and four-way coupling for accurate predictions.

Contribution

It introduces large-scale, realistic particle simulations with two- and four-way coupling in patient-specific geometries, improving deposition prediction accuracy.

Findings

Two-way coupling significantly increases upper airway deposition.

Four-way coupling reduces deposition by about 10% at certain dosages.

Parcel modeling effectively studies particle deposition across sizes.

Abstract

Inhalers spray over 100 million drug particles into the mouth, where a significant portion of the drug may deposit. Understanding how the complex interplay between particle and solid phases influence deposition is crucial for optimising treatments. Existing modelling studies neglect any effect of particle momentum on the fluid (one-way coupling), which may cause poor prediction of forces acting on particles. In this study, we simulate a realistic number of particles (up to 160 million) in a patient-specific geometry. We study the effect of momentum transfer from particles to the fluid (two-way coupling) and particle-particle interactions (four-way coupling) on deposition. We also explore the effect of tracking groups of particles (`parcels') to lower computational cost. Upper airway deposition fraction increased from 0.33 (one-way coupled) to 0.87 with two-way coupling and $10 \mu m$ particle diameter. Four-way coupling lowers upper airway deposition by approximately 10% at $100 \mu g$ dosages. We use parcel modelling to study deposition of $4 - 20 \mu m$ particles, observing significant influence of two-way coupling in each simulation. These results show that future studies should model realistic dosages for accurate prediction of deposition which may inform clinical decision-making.