Simulation of Particle Deposition in an Idealized Mouth with Different Small Diameter Inlets

Matida, Edgar; DeHaan, Wesley; Finlay, Warren H.; Lange, Carlos F.

doi:10.1080/02786820300932

Cited by 45 publications

(32 citation statements)

References 30 publications

(34 reference statements)

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“…This model is an average geometrical mouth-throat based on data from a CT scan, MRI scan, and living subjects. This idealized model has been the basis of many deposition studies, including deposition in aerosol drug delivery devices (14,56,57). A recent study showed that aerosol deposition in the idealized replica is in close agreement with those in the LRRI realistic mouth-throat replica for liquid aerosol and solid aerosol when the idealized replica is coated to prevent particle bounce (58).…”

Section: Deposition In the Oropharyngeal Regionsmentioning

confidence: 60%

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Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Cheng

2014

AAPS PharmSciTech

166

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Abstract. Aerosol delivery is noninvasive and is effective in much lower doses than required for oral administration. Currently, there are several types of therapeutic aerosol delivery systems, including the pressurized metered-dose inhaler, the dry powder inhaler, the medical nebulizer, the solution mist inhaler, and the nasal sprays. Both oral and nasal inhalation routes are used for the delivery of therapeutic aerosols. Following inhalation therapy, only a fraction of the dose reaches the expected target area. Knowledge of the amount of drug actually deposited is essential in designing the delivery system or devices to optimize the delivery efficiency to the targeted region of the respiratory tract. Aerosol deposition mechanisms in the human respiratory tract have been well studied. Prediction of pharmaceutical aerosol deposition using established lung deposition models has limited success primarily because they underestimated oropharyngeal deposition. Recent studies of oropharyngeal deposition of several drug delivery systems identify other factors associated with the delivery system that dominates the transport and deposition of the oropharyngeal region. Computational fluid dynamic simulation of the aerosol transport and deposition in the respiratory tract has provided important insight into these processes. Investigation of nasal spray deposition mechanisms is also discussed.

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Section: Deposition In the Oropharyngeal Regionsmentioning

confidence: 60%

“…CFD simulation of the flow pattern using the same oral cavity geometry and aerosol inlets of 3, 5, and 8 μm clearly showed an air jet from the inlet impinging on the back of the mouth (Fig. 8) (56). Deposition efficiency does not correlate with the impaction diameter, d ae 2 Q, which does not include the inlet diameter.…”

Section: Oral Deposition For the Dpismentioning

confidence: 98%

Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Cheng

2014

AAPS PharmSciTech

166

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“…Corrections for anisotropy of turbulence at boundary layers were also not employed. Some studies showed that the anisotropy of turbulence at boundary layers can greatly affect the calculation of particle deposition (such as Matida et al (2003) in respiratory track flows and Wang and James (1999) in channel flows). In a study conducted in a ventilated room, Zhao et al (2004) employed a discrete phase boundary layer treatment similar to the current study to simulate particle depositions.…”

Section: Boundary Conditionsmentioning

confidence: 99%

Dispersion of Expiratory Droplets in a General Hospital Ward with Ceiling Mixing Type Mechanical Ventilation System

Wan

Chao

et al. 2007

Aerosol Science and Technology

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This study investigated the dispersion characteristics of polydispersed droplets in a general hospital ward equipped with ceilingmixing type ventilation system. Injections of water test droplets containing non-volatile content were produced. The injections simulate human coughs with a similar droplet size distribution (peak size at 12 μm) and airflow rate (0.4 L/s). The dispersion of test droplets was measured in-situ by interferometric Mie imaging (IMI) method combined with an aerosol spectrometer. A multiphase numerical model was employed to simulate the droplet dispersion tracks to provide additional transient position tracking data. Results show that the small size group of droplets or droplet nuclei (initial size ≤45 μm) behaved airborne transmittable as some nuclei stayed airborne for more than 360 s. The dispersions were strongly affected by the ventilation airflow pattern. The expiratory droplets exhibited a two-stage lateral dispersion behavior, in which rapid dispersion was found in the early "initial dispersion" stage and then the dispersion became much slower in the subsequent "stable" stage. The exhaust air vents significantly enhanced lateral dispersions towards their direction. Droplets in the large size group (initial size = 87.5 μm and 137.5 μm) were subjected to heavy gravitational effect and stayed airborne for less than 30 s. Results indicate that the location of exhaust air vents has significant impact on the dispersion pattern of expiratory droplets. It should be carefully considered in designing ventilation systems for health-care settings.

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“…The relevant governing transport equations are solved in 3D models of the airways, which are discretized into interconnected small spatial elements (or control volumes) such as hexahedral, tetrahedral, or prism cells. Recent CFD studies of inhaled pharmaceutical aerosols have captured the effects of inhalers on transport and deposition in the mouth-throat region (34)(35)(36) and have predicted aerosol deposition through numerous generations of the upper (37)(38)(39) and lower TB airways. (40) However, prediction of aerosol transport and deposition throughout the lungs with CFD simulations (i.e., a CFD whole-lung model) remains challenging and requires simplifying techniques, which are actively being developed.…”

Section: Introductionmentioning

confidence: 99%

Validating Whole-Airway CFD Predictions of DPI Aerosol Deposition at Multiple Flow Rates

Longest

Tian

Khajeh-Hosseini-Dalasm

et al. 2016

Journal of Aerosol Medicine and Pulmonary Drug Delivery

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Background: The objective of this study was to compare aerosol deposition predictions of a new whole-airway CFD model with available in vivo data for a dry powder inhaler (DPI) considered across multiple inhalation waveforms, which affect both the particle size distribution (PSD) and particle deposition. Methods: The Novolizer DPI with a budesonide formulation was selected based on the availability of 2D gamma scintigraphy data in humans for three different well-defined inhalation waveforms. Initial in vitro cascade impaction experiments were conducted at multiple constant (square-wave) particle sizing flow rates to characterize PSDs. The whole-airway CFD modeling approach implemented the experimentally determined PSDs at the point of aerosol formation in the inhaler. Complete characteristic airway geometries for an adult were evaluated through the lobar bronchi, followed by stochastic individual pathway (SIP) approximations through the tracheobronchial region and new acinar moving wall models of the alveolar region. Results: It was determined that the PSD used for each inhalation waveform should be based on a constant particle sizing flow rate equal to the average of the inhalation waveform's peak inspiratory flow rate (PIFR) and mean flow rate [i.e., AVG(PIFR, Mean)]. Using this technique, agreement with the in vivo data was acceptable with <15% relative differences averaged across the three regions considered for all inhalation waveforms. Defining a peripheral to central deposition ratio (P/C) based on alveolar and tracheobronchial compartments, respectively, large flow-rate-dependent differences were observed, which were not evident in the original 2D in vivo data. Conclusions: The agreement between the CFD predictions and in vivo data was dependent on accurate initial estimates of the PSD, emphasizing the need for a combination in vitro-in silico approach. Furthermore, use of the AVG(PIFR, Mean) value was identified as a potentially useful method for characterizing a DPI aerosol at a constant flow rate.

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Simulation of Particle Deposition in an Idealized Mouth with Different Small Diameter Inlets

Abstract: The deposition of monodisperse particles (1.0-12.5 µm diameter) in an idealized mouth geometry has been studied numerically for three different inlet diameters

Cited by 45 publications

References 30 publications

Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Mechanisms of Pharmaceutical Aerosol Deposition in the Respiratory Tract

Dispersion of Expiratory Droplets in a General Hospital Ward with Ceiling Mixing Type Mechanical Ventilation System

Validating Whole-Airway CFD Predictions of DPI Aerosol Deposition at Multiple Flow Rates

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