Application of heliox for optimized drug delivery through respiratory tract

Abstract

Understanding the transportation and deposition (TD) of inhaled particles in the upper respiratory tract is crucial for predicting health risks and treating pulmonary diseases. The available literature reports highly turbulent flow in the extrathoracic (ET) region during normal breathing, which leads to higher deposition of the drug aerosol in this region. To improve the targeted deposition of inhaled drugs, in the tracheobronchial airways, it is essential to understand the flow and particle transport dynamics and reduce the turbulence behavior at the ET region. The less-dense heliox gas could reduce the turbulence behavior at the ET; however, the knowledge of heliox inhalation therapies in drug aerosol TD remains underachieved to realize the full potential for assisted breathing and drug delivery. Additionally, the impact of the inhalation of heliox mixed with other gases on particle deposition is missing in the literature. Therefore, this study aims to develop a mixture model to advance the knowledge of inhalation therapy. A heliox (78% helium and 22% oxygen) and a mixture of heliox and air are used to understand the flow behavior and particle TD in airways. The impact of different inhalation and Stokes numbers on the deposition efficiencies in the ideal and age-specific upper airways is studied. The study reports that less-dense heliox gas has lower turbulence intensity and results in lower deposition efficiency in the G3–G5 lung airways compared to air and mixture inhalations. Moreover, slightly higher deposition efficiencies during mixture inhalation as compared to air inhalation are found in the upper airways. The deposition patterns of different inhalations obtained in this study could help improve targeted drug delivery into the upper and deeper lung airways.

Optimal Treatment of Tumor in Upper Human Respiratory Tract Using Microaerosols

“…The Lagrangian approach is used to simulate the particle TD in the lung airways. The dynamics of each particle are controlled through the force balance equation: d u⃗ p d t = F D false( u⃗ − u⃗ normalp false) + g⃗ ρ p false( ρ normalp − ρ false) where u and u p represent the velocity of continuous and discrete phases, respectively, g is the gravitational acceleration, ρ p is particle density, which is taken as 1100 kg/m 3 . − F D ( u⃗ – u⃗ p ) represents the drag force per particle mass, and the F D for the spherical particle is determined using the following relation: F D = 1 2 C D π d p 2 4 ρ false( v⃗ normalp − v⃗ false) false| v⃗ normalp − v⃗ false| where C D is the drag coefficient, d p is the diameter of the particle, and v p is the particle velocity. For particle deposition, a trap condition is applied on the wall of the lung model and an escape condition is applied at all outlets of the airways, which corresponds to the exit point at generation six. , This ensures that when a particle strikes the inner wall of the lung, the fate of that particle will be considered trapped or deposited at that point of the airway.…”

“…The dynamics of each particle are controlled through the force balance equation: where u and u p represent the velocity of continuous and discrete phases, respectively, g is the gravitational acceleration, ρ p is particle density, which is taken as 1100 kg/m 3 . 51 − 53 F D ( u⃗ – u⃗ p ) represents the drag force per particle mass, and the F D for the spherical particle is determined using the following relation: where C D is the drag coefficient, d p is the diameter of the particle, and v p is the particle velocity. For particle deposition, a trap condition is applied on the wall of the lung model and an escape condition is applied at all outlets of the airways, which corresponds to the exit point at generation six.…”

Numerical simulation of a nebulizer with multiple orifices

“…This aerosol is in the form of a diverging stream of tiny droplets that are in the diameter range from 3 µm to 6 µm such that patients can inhale them deep into lungs to treat a variety of diseases. This therapy is called inhalation therapy, also known as the pulmonary route of drug administration [2]. There are different types of nebulizers available on the market; the research reported in this paper concerns the operation of a vibrating mesh nebulizer (VMN).…”