A CFD Investigation on the Aerosol Drug Delivery in the Mouth–Throat Airway Using a Pressurized Metered-Dose Inhaler Device

Abstract

Inhalation therapy involving a pressurized metered-dose inhaler (pMDI) is one of the most commonly used and effective treatment methods for patients with asthma. The purpose of this study was to develop a computational fluid dynamics (CFD) model to characterize aerosol flow issued from a pMDI into a simulated mouth–throat geometry. The effects of air flow rate and cone angle were analyzed in detail. The behaviour of the multiphase flow initiated at the inhaler actuation nozzle and extended through the mouth–throat airway was simulated based on the Eulerian-Lagrangian discrete phase model, with the k-ω model applied for turbulency. We validated our model against published experimental measurements and cover the hydrodynamic aspect of the study. The recirculation we observed at the 90° bend inside the mouth–throat airway resulted in the selective retention of larger diameter particles, and the fluid flow patterns were correlated with drug deposition behaviour. Enhancing air flow rates up to three times reduced the aerodynamic particle diameters to 20%. We also observed that, as cone angle increased, mouth deposition increased; an 8° cone angle was the best angle for the lowest mouth–throat deposition.

Aerosol deposition and emission from a United States Pharmacopeia‐induction port when using a pressurized metered‐dose inhaler with and without a valved holding chamber

“…For the IP, Figure 4A shows the CFD‐predicted contours coloured as a function of air velocity for case I (i.e., injection of particles from the pMDI). As the airflow approaches the 90° bend, centrifugal forces alter the velocity profile, shifting it towards the outer wall of the bend, as reported by Dastoorian et al [ 19 ] In other words, within the elbow, the maximum velocity transitions from the inner wall to the outer wall of the IP. Furthermore, low velocity zones are observed both in the bend on the external wall and downstream of the bend in the vicinity of the inner surface.…”

“…The escape fraction curves determined by Equation (19) for both the IP and the VHC can be utilized for calculating the particle size distribution (PSD) deposited in the NGI stages. For case I, the PSD in the NGI stages is obtained by multiplying the PSD emitted from the pMDI by the deposition fraction function of the IP (see Figure 2A).…”

“…Bass and Longest [ 18 ] simulated the deposition of inhalable particles in a 90° bend geometry using CFD and proposed user‐defined functions to correct over‐prediction of deposition. Dastoorian et al [ 19 ] studied the effect of higher flow rates on recirculation using CFD simulations and found that the inclusion of Brownian motion in the force balance for particles increased the deposition of fine particles at the 90° bend.…”

Engineering innovations in medicine and biology: Revolutionizing patient care through mechanical solutions

“…Moreover, these simulations contribute to the evaluation of inhaler device designs, leading to the development of more efficient and patient-friendly delivery systems. For example, Dastoorian et al [ 177 ] conducted a CFD study to investigate the influence of flow rates and cone angles on spray plume characteristics and drug particle deposition in a simulated mouth-throat airway. They validated their CFD model using experimental data.…”

The Impact of Actuator Nozzle and Surroundings Condition on Drug Delivery using Pressurized-Metered Dose Inhalers

“…However, their study showed no correlations between aerosol performance/plume angles/ nozzle design with aerosol deposition. Dastoorian et al (2022) studied the effect of plume angle on drug deposition and found that smaller cone angles produced larger particles, but larger cone angles increased mouth deposition. Duke et al (2021b) discovered that pMDI actuators with twin-hole orifices with smaller diameter holes (0.22 mm) could produce up to 75% more FPF compared to the conventional single-hole orifices.…”