Cerebral hemodynamics during arterial and CO<sub>2</sub> pressure changes: in vivo prediction by a mathematical model

Ursino, Mauro; Minassian, Aram Ter; Lodi, Carlo Alberto; Beydon, L.

doi:10.1152/ajpheart.2000.279.5.h2439

Cited by 78 publications

(117 citation statements)

References 49 publications

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“…Our cerebral hemodynamics model is similar to the previous models developed by Ursino et al (36,39). It consists of three lumped cerebral vascular segments: cerebral arteries, capillaries, and veins, as shown in Fig.…”

Section: Cerebral Hemodynamicsmentioning

confidence: 97%

“…Specifically, an increase in CBF causes Ca to decrease and Ra to increase, indicating vasoconstriction, whereas a decrease in cerebral blood flow increases Ca and decreases Ra, causing vasodilation. In characterizing autoregulation, we have adopted the following empirical transfer function developed by Ursino et al (39) ẋ aut ϭ…”

Section: Cbf Regulationmentioning

confidence: 99%

“…None have considered the effect of CO 2 on cerebral hemodynamics and autoregulation or described the gas exchange between cerebral vessels and brain tissue. Ursino et al (37,39) and Czosnyka et al (5) included CO 2 reactivity in their modeling studies of intracranial dynamics. However, their models did not include gas transport in brain tissue and thus can not simulate the impact of cerebral hemodynamic changes on brain tissue gas content.…”

mentioning

confidence: 99%

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Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

Lu¹,

Clark²,

Ghorbel³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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. Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model. Am J Physiol Heart Circ Physiol 286: H584-H601, 2004. First published August 28, 2003 10.1152/ajpheart.00594.2003.-The goal of this work is to study the cerebral autoregulation, brain gas exchange, and their interaction by means of a mathematical model. We have previously developed a model of the human cardiopulmonary (CP) system, which included the whole body circulatory system, lung and peripheral tissue gas exchange, and the central nervous system control of arterial pressure and ventilation. In this study, we added a more detailed description of cerebral circulation, cerebrospinal fluid (CSF) dynamics, brain gas exchange, and cerebral blood flow (CBF) autoregulation. Two CBF regulatory mechanisms are included: autoregulation and CO2 reactivity. Central chemoreceptor control of ventilation is also included. We first established nominal operating conditions for the cerebral model in an open-loop configuration using data generated by the CP model as inputs. The cerebral model was then integrated into the larger CP model to form a new integrated CP model, which was subsequently used to study cerebral hemodynamic and gas exchange responses to test protocols commonly used in the assessment of CBF autoregulation (e.g., carotid artery compression and the thigh-cuff deflation test). The model can closely mimic the experimental findings and provide biophysically based insights into the dynamics of cerebral autoregulation and brain tissue gas exchange as well as the mechanisms of their interaction during test protocols, which are aimed at assessing the degree of autoregulation. With further refinement, our CP model may be used on measured data associated with the clinical evaluation of the cerebral autoregulation and brain oxygenation in patients. physiological modeling; thigh-cuff test; carotid artery compression NORMAL CEREBRAL AUTOREGULATION provides a constant cerebral blood flow (CBF) over a wide range of cerebral perfusion pressures (CPP) (1, 25). Because this regulatory mechanism is complex, several investigators have found that mathematical models can help guide experimental design and provide explanations of experimental results (8, 14-16, 18, 32, 36). These models have largely been directed at developing mechanistic descriptions of cerebral autoregulation or the dynamics of intracranial systems. None have considered the effect of CO 2 on cerebral hemodynamics and autoregulation or described the gas exchange between cerebral vessels and brain tissue. Ursino et al. (37,39) and Czosnyka et al. (5) included CO 2 reactivity in their modeling studies of intracranial dynamics. However, their models did not include gas transport in brain tissue and thus can not simulate the impact of cerebral hemodynamic changes on brain tissue gas content.We recently presented a modeling study of human whole body gas exchange (20), in which our previous human cardiopulmonary (CP) model (19) was significantly extended to include descriptions of ...

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Section: Cerebral Hemodynamicsmentioning

confidence: 97%

Section: Cbf Regulationmentioning

confidence: 99%

mentioning

confidence: 99%

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Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

Lu¹,

Clark²,

Ghorbel³

et al. 2004

American Journal of Physiology-Heart and Circulatory Physiology

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show abstract

“…Mathematical equations for peripheral circulation and for regulatory mechanism action in the individual districts have the same form as used previously for the overall cerebrovascular bed [2] (but with different parameter values).…”

Section: The Pial Artery Circulationmentioning

confidence: 99%

“…With that model, we were able to simulate several physiological phenomena and clinical results on human patients [2].…”

Section: Introductionmentioning

confidence: 99%

A comprehensive cerebrovascular simulation model for teaching and research

Ursino¹,

Giannessi²,

Murray³

2007

Modelling in Medicine and Biology VII

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A comprehensive mathematical model of cerebral hemodynamics, with separate regulation of multiple brain regions, is presented. The main sectors included in the model are: the Circle of Willis, the hemodynamic circulation in the six districts perfused by the cerebral arteries, venous return with collapsible veins, cerebrospinal fluid circulation, and intracranial elasticity. Furthermore, each cerebral district is independently regulated following changes in cerebral perfusion pressure and CO 2 tension. In this work, the model is used to analyze cerebral hemodynamics during unilateral stenosis or occlusion of an internal carotid artery, as well as to assess the compensatory role of the Circle of Willis and of cerebrovascular regulatory mechanisms. Results show that, in normal subjects, the action of local blood flow regulation mechanisms and compensation by the Circle of Willis ensure adequate ipsilateral blood flow even in the presence of total unilateral internal carotid artery occlusion. However, a steal phenomenon is observed (i.e., a decrease of blood flow in the ipsilateral region) following hypercapnia. Sensitivity analysis on the calibre of the communicating arteries reveals that the anterior communicating artery plays a pivotal role in ensuring blood flow in the ipsilateral side during internal carotid artery stenosis. The model may have important clinical and educational applications, allowing the assessment of blood perfusion to different brain regions in various pathophysiological cases.

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Physiological Systems Modeling

Smith

Starko

2006

Encyclopedia of Medical Devices and Instrumentation

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This article discusses modeling as a device that you might use in research, education, or the practice of medicine or engineering. The purpose of the article is to allow you to explore, examine, and perhaps even use models, just as you would a device. Physiological models are almost unique among equipment, because a major use is education. Through physiological models, one can learn about physiology, pharmacology, scientific concepts, and clinical situations. The main way to use a model is through simulation or a simulator. We distinguish between simulation and simulators, the former being much more common. We usually give enough detail about a model so that the reader can decide whether to make the effort to locate the reference(s), author(s), and/or a simulator. The article is divided by systems. Each section describes some characteristics and peculiarities of the system, followed by a description of the models available, highlighting some of the ones that can be easily and inexpensively used. We concentrate on the central nervous, cardiovascular and thermal regulatory systems, mainly in the area of classical, or macro, physiology. The body and its systems depend on control systems, and these are emphasized, including the fascinating phenomenon of autoregulation, which has its own section. Autoregulation can be astoundingly simple or amazingly complex, but never completely independent of other regulatory systems. The past, present, and future of physiological systems modeling are also explore. The future is particularly exciting. The physiome project is to physiology what the genome project has been to genetics.

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Cerebral hemodynamics during arterial and CO₂ pressure changes: in vivo prediction by a mathematical model

Cited by 78 publications

References 49 publications

Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

A comprehensive cerebrovascular simulation model for teaching and research

Physiological Systems Modeling

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Cerebral hemodynamics during arterial and CO2 pressure changes: in vivo prediction by a mathematical model

Cited by 78 publications

References 49 publications

Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

A comprehensive cerebrovascular simulation model for teaching and research

Physiological Systems Modeling

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Product

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Cerebral hemodynamics during arterial and CO₂ pressure changes: in vivo prediction by a mathematical model