Gas and aerosol mixing in the acinus

Tsuda, Akira; Henry, F. S.; Butler, James P.

doi:10.1016/j.resp.2008.02.010

Cited by 70 publications

(76 citation statements)

References 68 publications

(78 reference statements)

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“…Recent CFD simulations in an alveolar duct model (Butler & Tsuda, 1997;Tsuda et al, 1995Tsuda et al, , 2008Tsuda et al, , 2002 as well as laboratory measurements (Tippe & Tsuda, 1999) suggest that flow-induced alveolar mixing, caused by the irreversibility of alveolar flow combined with a stretched and folded pattern of streamlines, can lead to a mixing of the inhaled tidal air with the residual air in the lungs. In whole lung deposition models, alveolar mixing can be considered by an empirical mixing factor, derived from experimental data .…”

Section: Fluid Dynamicsmentioning

confidence: 99%

Modelling inhaled particle deposition in the human lung—A review

Hofmann

2011

Journal of Aerosol Science

389

215

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Section: Fluid Dynamicsmentioning

confidence: 99%

Modelling inhaled particle deposition in the human lung—A review

Hofmann

2011

Journal of Aerosol Science

389

215

View full text Add to dashboard Cite

“…10,18 We will first discuss the steady streaming phenomenon and its characteristics, and then relate it to the origin of various interface stretching and folding patterns observed in the duct, in the duct mouth, and within the cavity. Consider an oscillating flow in a 2D long, straight channel with multiple rectangular grooves located periodically on the lower part of the channel as shown in Fig.…”

Section: A Flow In a 2d Channelmentioning

confidence: 99%

“…First, a stagnation saddle point had been attributed before for chaotic mixing in the alveoli. 10,14,15,18 Second, the observed flow topology helps identify advection regions of interest for analysis in subsequent sections.…”

Section: B Alveolar Flow Structurementioning

confidence: 99%

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Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows

et al. 2011

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Study of mixing is important in understanding transport of submicron sized particles in the acinar region of the lung. In this article, we investigate transport in view of advective mixing utilizing Lagrangian particle tracking techniques: tracer advection, stretch rate and dispersion analysis. The phenomenon of steady streaming in an oscillatory flow is found to hold the key to the origin of kinematic mixing in the alveolus, the alveolar mouth and the alveolated duct. This mechanism provides the common route to folding of material lines and surfaces in any region of the acinar flow, and has no bearing on whether the geometry is expanding or if flow separates within the cavity or not. All analyses consistently indicate a significant decrease in mixing with decreasing Reynolds number ͑Re͒. For a given Re, dispersion is found to increase with degree of alveolation, indicating that geometry effects are important. These effects of Re and geometry can also be explained by the streaming mechanism. Based on flow conditions and resultant convective mixing measures, we conclude that significant convective mixing in the duct and within an alveolus could originate only in the first few generations of the acinar tree as a result of nonzero inertia, flow asymmetry, and large Keulegan-Carpenter ͑K C ͒ number.

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“…Thus several researchers have included the moving wall feature of acinar airways while modeling aerosol deposition (6,37,68,99). Furthermore, few studies suggest that airflow recirculation and irreversibility play important role in convective mixing of aerosol particles between tidal air and residual air in acinar airways (68,155). Taking all together, it seems crucial to incorporate moving wall and ventilation features while modeling acinar airways for close-to-real estimation of aerosol deposition.…”

mentioning

confidence: 99%

Computational and bioengineered lungs as alternatives to whole animal, isolated organ, and cell-based lung models

Patel

Gauvin

Absar

et al. 2012

American Journal of Physiology-Lung Cellular and Molecular Phys

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Development of lung models for testing a drug substance or delivery system has been an intensive area of research. However, a model that mimics physiological and anatomical features of human lungs is yet to be established. Although in vitro lung models, developed and fine-tuned over the past few decades, were instrumental for the development of many commercially available drugs, they are suboptimal in reproducing the physiological microenvironment and complex anatomy of human lungs. Similarly, intersubject variability and high costs have been major limitations of using animals in the development and discovery of drugs used in the treatment of respiratory disorders. To address the complexity and limitations associated with in vivo and in vitro models, attempts have been made to develop in silico and tissue-engineered lung models that allow incorporation of various mechanical and biological factors that are otherwise difficult to reproduce in conventional cell or organ-based systems. The in silico models utilize the information obtained from in vitro and in vivo models and apply computational algorithms to incorporate multiple physiological parameters that can affect drug deposition, distribution, and disposition upon administration via the lungs. Bioengineered lungs, on the other hand, exhibit significant promise due to recent advances in stem or progenitor cell technologies. However, bioengineered approaches have met with limited success in terms of development of various components of the human respiratory system. In this review, we summarize the approaches used and advancements made toward the development of in silico and tissue-engineered lung models and discuss potential challenges associated with the development and efficacy of these models. bioengineered lung; computational modeling; in silico; lung models; tissue engineering LUNG DISEASES ARE THE THIRD leading cause of deaths in the United States that translate into one in six deaths. More than 400,000 Americans die of lung disease every year and around 35 million are now living with chronic lung problems (1). Therefore, there is an important need to understand as to how a new drug entity or a novel formulation may influence the anatomy, physiology, and pathogenesis of lungs and vice versa.The human lung has an approximate volume of six liters, contains about 300 million alveoli, and provides a total surface area of 100 square meters as blood-air interface, which is packed into an elastic dynamic structure responsible for gas exchange (159). The human airway wall is a connective tissue that includes smooth muscle cells (SMC), mucus glands, blood vessels, and fibroblasts surrounded by a collagen-rich extracellular matrix (ECM). Epithelial cells, responsible for the efficient oxygen and carbon dioxide transfer, are at the interface between air and the connective tissue and are attached to an underlying basement membrane. The respiratory system is the site of a variety of pulmonary diseases such as asthma, bronchitis, pneumonia, cystic fibrosis, emphysema, a...

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Gas and aerosol mixing in the acinus

Cited by 70 publications

References 68 publications

Modelling inhaled particle deposition in the human lung—A review

Modelling inhaled particle deposition in the human lung—A review

Steady streaming: A key mixing mechanism in low-Reynolds-number acinar flows

Computational and bioengineered lungs as alternatives to whole animal, isolated organ, and cell-based lung models

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