Computer simulation of cererrovascular circulation: Assessment of intracranial hemodynamics during induction of anesthesia

Bekker, Alex; Wolk, S.; Turndorf, Herman; Kristol, D.; Ritter, Arthur

doi:10.1007/bf02199704

Cited by 13 publications

(5 citation statements)

References 47 publications

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“…The windkessel model can be represented by a circuit consisting of two resistors R S and RP (mmHg ⅐ s/cm 3 ) and a capacitor CS (cm 3 /mmHg) (see Fig. 2).…”

Section: Modelingmentioning

confidence: 99%

Dynamics of cerebral blood flow regulation explained using a lumped parameter model

Olufsen

Nadim

Lipsitz

2002

American Journal of Physiology-Regulatory, Integrative and Comp

107

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To better understand the cardiovascular response to hypotension, we used a windkessel model with two resistors and a capacitor to reproduce beat-to-beat changes in middle cerebral artery blood flow velocity (transcranial Doppler measurements) in response to arterial pressure changes measured in the finger (Finapres). The resistors represent lumped systemic and peripheral resistances in the cerebral vasculature, whereas the capacitor represents a lumped systemic compliance. Ten healthy young subjects were studied during posture change from sitting to standing. Dynamic variations of the peripheral and systemic resistances were extracted from the data on a beat-to-beat basis. The model shows an initial increase, followed approximately 10 s later by a decline in cerebrovascular resistance. The model also suggests that the initial increase in cerebrovascular resistance can explain the widening of the cerebral blood flow pulse observed in young subjects. This biphasic change in cerebrovascular resistance is consistent with an initial vasoconstriction, followed by cerebral autoregulatory vasodilation. cerebral autoregulation; arterial modeling THE DYNAMIC CEREBRAL BLOOD FLOW RESPONSE to sudden hypotension during posture change is poorly understood. The aim of this work is to use a lumped parameter model of cerebral blood flow to analyze changes in key parameters (systemic and peripheral cerebrovascular resistances) during posture change from sitting to standing. Such a model sheds light on vascular adaptation to hypotensive stress and could ultimately help determine the changes in cerebral autoregulation that occur in aging, hypertension, and other clinical conditions.The present work focuses on the middle cerebral artery (MCA) and its peripheral vascular bed. The MCA is considered a conduit vessel, and the smaller arteries and arterioles that branch off from the MCA are modeled as resistance vessels that dilate or constrict to restore blood flow when the perfusion pressure decreases or increases, respectively. The cerebral autoregulatory response to pressure reduction during posture change from sitting to standing is vasodilation of the arterioles. However, the dynamic cerebral blood flow response to posture change reflects not only the relative contributions from the peripheral cerebrovascular resistance, but also changes in systemic resistance, compliance, and heart rate.To understand the regulatory response, transcranial Doppler (TCD) measurements of cerebral blood flow velocity in the MCA and Finapres measurements of arterial pressure in the finger from 10 healthy young subjects were analyzed using a three-element windkessel model. Blood flow in the MCA was obtained by multiplying the blood flow velocity by the area of the MCA (assumed constant throughout the study). As shown in Fig. 1, when the subject stands up (after 60 s of sitting) the pressure falls and the blood flow pulse widens (systolic minus diastolic value is increased). After subject stands for 20 s (i.e., 80 s into the study), both arterial pressure ...

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“…The windkessel model can be represented by a circuit consisting of two resistors R S and RP (mmHg ⅐ s/cm 3 ) and a capacitor CS (cm 3 /mmHg) (see Fig. 2).…”

Section: Modelingmentioning

confidence: 99%

Dynamics of cerebral blood flow regulation explained using a lumped parameter model

Olufsen

Nadim

Lipsitz

2002

American Journal of Physiology-Regulatory, Integrative and Comp

107

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“…Sudden changes in haemodynamic parameters during the induction of anaesthesia are particularly important in patients with additional cardiovascular and CNS diseases. In patients with the latter, impaired autoregulation of the cerebral circulation is often observed, and CPP is found to passively "follow" the changes to MAP [42,43]. To prevent such adverse effects of laryngoscopy and intubation, many authors suggest local anaesthesia of the larynx with lignocaine and used the additional dose of a hypnotic immediately before endotracheal intubation or to apply of esmolol [30,34,37].…”

Section: Discussionmentioning

confidence: 99%

Wpływ propofolu na prędkość przepływu krwi w tętnicy środkowej mózgu (VMCA) u chorych z niepękniętym tętniakiem wewnątrzczaszkowym podczas indukcji znieczulenia ogólnego

Karwacki

Niewiadomski²,

Witkowska³

et al. 2018

Anaesthesiol Intensive Ther

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Background: The estimated prevalence of unruptured intracranial aneurysms is 3%. Standard monitoring does not enable one to assess the influence of anaesthetics on the factors determining intracranial homeostasis. Thanks to transcranial Doppler ultrasonography, middle cerebral artery flow velocity (V MCA), reflecting cerebral blood flow, can be measured. The aim of the study was to assess the effects of propofol on intracranial homeostasis in patients with unruptured intracranial aneurysms during the induction of anaesthesia based on V MCA changes. Methods: The study encompassed 21 patients (group II) anaesthetised for elective craniotomy due to unruptured intracranial aneurysms. The control group (group I) included 21 patients who underwent discoidectomy. V MCA , as well as HR, MAP, etCO 2 , and SpO 2 were monitored at the following time points: T 0 -onset of study; T 1 -after 1 minute; T 2 -onset of preoxygenation; T 3 -after 1 minute of preoxygenation; T 4 -administration of fentanyl; T 5 -1 minute after fentanyl; T 6 -administration of propofol; T 7 -1 minute after propofol; T 8 -intubation; T 9 -1 minute after intubation; T 10 -2 minutes after intubation. results: In both groups, no changes in mean HR, etCO 2 and SpO 2 were observed at the successive time points of observation. In groups I and II, an MAP decrease between T 6 and T 7 and an MAP increase between T 7 and T 9 were noted. There were no intergroup differences in mean values of MAP at the times of observation. In both groups and bilaterally, a V MCA decrease was recorded between T 6 and T 7 and an increase between T 7 and T 8 . There were no intergroup differences in mean values of V MCA at the times of observation. In both groups, a weak correlation between V MCA and MAP changes was found bilaterally. Conclusions: Propofol depresses the cerebral circulation during the induction of anaesthesia. The presence of an unruptured aneurysm does not affect the reactivity of the cerebral vessels during the induction of anaesthesia with propofol.

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“…Simultaneous monitoring of these variables along with intracranial pressure (ICP) and arterial blood pressure (ABP) can provide valuable physiologic perspectives in various intracranial pathologies. Through the analysis of TCD waveform, many authors have attempted to investigate the relationship between the cerebral blood flow (CBF) and cerebrospinal fluid (CSF) dynamics, proposing several mathematical and hydrodynamic models derived from signals as input, with the most common of them being ABP, ICP, and FV (Hoffmann & Zierski, ; Bekker, Wolk, Turndorf, Kristol, & Ritter, ).…”

Section: Basic Methodsmentioning

confidence: 99%

Transcranial Doppler: a stethoscope for the brain‐neurocritical care use

Robba

Cardim

Sekhon

et al. 2017

J of Neuroscience Research

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Transcranial Doppler (TCD) ultrasonography is a noninvasive bedside monitoring technique that can evaluate cerebral blood flow hemodynamics in the intracranial arterial vasculature. TCD allows assessment of linear cerebral blood flow velocity, with a high temporal resolution and is inexpensive, reproducible, and portable. The aim of this review is to provide an overview of the most commonly used TCD derived signals and measurements used commonly in neurocritical care. We describe both basic (flow velocity, pulsatility index) and advanced concepts, including critical closing pressure, wall tension, autoregulation, noninvasive intracranial pressure, brain compliance, and cerebrovascular time constant; we also describe the clinical applications of TCD to highlight their utility in the diagnosis and monitoring of cerebrovascular diseases as the "stethoscope for the brain."

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Computer simulation of cererrovascular circulation: Assessment of intracranial hemodynamics during induction of anesthesia

Abstract: The presented simulation allows comparison of various drug administration schedules to control intracranial pressure and preserve cerebral blood flow during induction of anesthesia. The model developed can be extended to analyze more complex intraoperative events by adding new submodels.

Cited by 13 publications

References 47 publications

Dynamics of cerebral blood flow regulation explained using a lumped parameter model

Dynamics of cerebral blood flow regulation explained using a lumped parameter model

Wpływ propofolu na prędkość przepływu krwi w tętnicy środkowej mózgu (VMCA) u chorych z niepękniętym tętniakiem wewnątrzczaszkowym podczas indukcji znieczulenia ogólnego

Transcranial Doppler: a stethoscope for the brain‐neurocritical care use

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