Modeling the bifurcating flow in an asymmetric human lung airway

Liu, Yang; So, R. M. C.; Zhang, Chuhua

doi:10.1016/s0021-9290(03)00064-2

Cited by 89 publications

(56 citation statements)

References 18 publications

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“…The uppermost airways have a higher proportion of cartilage than those that are more peripheral, and they are proportionately stiffer (105). While the airways are known to deform with a change in lung volume, they have generally been assumed to be rigid structures in numerical studies that compute air pressure and flow (5,58,98). This is in contrast to numerical studies of blood vessel perfusion, where the interaction between transmural pressure and the mechanics of the compliant vessel wall has been considered (74,90,97).…”

Section: Airflow-induced Shear Stressmentioning

confidence: 99%

Airway Gas Flow

Tawhai

Lin

2011

Comprehensive Physiology

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Local characteristics of airflow and its global distribution in the lung are determined by interaction between resistance to flow through the airways and the compliance of the tissue, with tissue compliance dominating flow distribution in the healthy lung. Current understanding is that conceptualizing the airways of the lung as a system of smooth adjoined cylinders through which air traverses laminarly is insufficient for understanding flow and energy dissipation and is particularly poor for predicting physiologically realistic transport of particles by the airflow. With rapid advances in medical imaging, computer technologies, and computational techniques, computational fluid dynamics is now becoming a viable tool for providing detailed information on the mechanics of airflow in the human respiratory tract. Studies using such techniques have shown that the upper airway (specifically its development of a turbulent laryngeal jet in the trachea), airway geometry, branching and rotation angle, and the pattern of joining of successive bifurcations are important in determining airflow structures. It is now possible to compute airflow in physical domains that are anatomically accurate and subject specific, enabling comparisons among intersubjects, that among subjects of different ages, and that among different species.

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Section: Airflow-induced Shear Stressmentioning

confidence: 99%

Airway Gas Flow

Tawhai

Lin

2011

Comprehensive Physiology

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“…Thus far, most of the attempts in modeling aerosol deposition in lungs were carried out either using highly simplified geometry models of human lungs (4, 5) or using anatomybased models of lung with fewer generations and limited number of airways (60,97,98,109,110). Morphometric models of human airways that have been developed to compute aerosol deposition included typical-path models (168, 169) based on idealized geometry and multipath models comprised of asymmetric airway geometry (5).…”

Section: In Silico Lung Modelingmentioning

confidence: 99%

“…Disease conditions also make the overall airway mechanics very complex. In addition, earlier computational fluid dynamics (CFD) models were required to use simple airway geometries incorporating only few generations of tracheobronchial tree because of computational limitations (32,33,47,76,86,94,98,(171)(172)(173). Lately, experiments conducted by Nowak et al (124) demonstrated that a general model of airway tree based on standardized geometry is not suitable to predict aerosol deposition and concluded that more practical models generated from imaging techniques are required, since geometry of the airways has a strong impact on the aerosol deposition.…”

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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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“…Most of the studies undertaken to understand the influence of the particle properties, respiratory action, and morphological characteristics have considered the inhalation step (Liu et al, 2003 Inthavong et al (2010) conducted a numerical study of the deposition of pharmaceutical aerosols in the first six generations of the lung, considering breath holding. However, the velocity fields and the influence of this action on particle deposition were not explored in detail.…”

Section: Introductionmentioning

confidence: 99%

A CFD Study of Deposition of Pharmaceutical Aerosols Under Different Respiratory Conditions

Augusto

Lopes

Gonçalves

2016

Braz. J. Chem. Eng.

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-Respiratory diseases have received increasing attention in recent decades. Airway bifurcations are difficult regions to study, and computational fluid dynamics (CFD) offers an alternative way of evaluating the behavior of pharmaceutical aerosols used in the treatment of respiratory disorders. In this work, particle deposition was analyzed using a three-dimensional model with four ramifications (three bifurcations), under different respiratory conditions: inhalation, exhalation, and breath holding. The main aim of the work was to verify the medical recommendation to hold one's breath during a few seconds after inhaling pharmaceutical aerosols, rather than exhaling immediately after the inhalation. The deposition of particles with 5 µm diameter was considered. The results showed that the number of aerosols collected on the airway walls was higher for the situation of breath holding, which supported the medical recommendation.

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Modeling the bifurcating flow in an asymmetric human lung airway

Cited by 89 publications

References 18 publications

Airway Gas Flow

Airway Gas Flow

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

A CFD Study of Deposition of Pharmaceutical Aerosols Under Different Respiratory Conditions

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