Relationships among cerebral perfusion pressure, autoregulation, and transcranial Doppler waveform: a modeling study

Ursino, Mauro; Giulioni, Marco; Lodi, Carlo Alberto

doi:10.3171/jns.1998.89.2.0255

Cited by 78 publications

(34 citation statements)

References 43 publications

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“…When ABP is extremely low, systolic CBF also starts to decrease and CBF pulse amplitude decreases. This prediction agrees well with the previously modeling study of Ursino et al (35), which indicates that three characteristic zones exits in the cerebral blood velocity response to reduced perfusion pressure with intact autoregulation. As shown in Fig.…”

Section: Open-loop Testingsupporting

confidence: 82%

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: Open-loop Testingsupporting

confidence: 82%

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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“…An increase in CVC indicates increased conductance at the pial level, to maintain CBF in the posterior region. 32 Reductions in blood flow in the posterior region of the brain may cause an interruption of the blood supply to the medulla oblongata, which contains autonomic control centers, and discrete regions responsible for consciousness. 33 An increase in PCAcvc to preferentially maintain perfusion of the cardiovascular and respiratory centers has been highlighted in response to headup tilt in AB, 22,34 and an exaggerated adaptation of this response may explain the widely reported 'remarkable tolerance to orthostatic hypotension' in the SCI population.…”

Section: Discussionmentioning

confidence: 99%

Regional Neurovascular Coupling and Cognitive Performance in Those with Low Blood Pressure Secondary to High-Level Spinal Cord Injury: Improved by Alpha-1 Agonist Midodrine Hydrochloride

Phillips

Warburton

Ainslie

et al. 2014

J Cereb Blood Flow Metab

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Individuals with high-level spinal cord injury (SCI) experience low blood pressure (BP) and cognitive impairments. Such dysfunction may be mediated in part by impaired neurovascular coupling (NVC) (i.e., cerebral blood flow responses to neurologic demand). Ten individuals with SCI 4T6 spinal segment, and 10 age-and sex-matched controls were assessed for beat-by-beat BP, as well as middle and posterior cerebral artery blood flow velocity (MCAv, PCAv) in response to a NVC test. Tests were repeated in SCI after 10 mg midodrine (alpha 1 -agonist). Verbal fluency was measured before and after midodrine in SCI, and in the control group as an index of cognitive function. At rest, mean BP was lower in SCI (70 ± 10 versus 92 ± 14 mm Hg; Po0.05); however, PCAv conductance was higher (0.56 ± 0.13 versus 0.39 ± 0.15 cm/second/mm Hg; Po0.05). Controls exhibited a 20% increase in PCAv during cognition; however, the response in SCI was completely absent (Po0.01). When BP was increased with midodrine, NVC was improved 70% in SCI, which was reflected by a 13% improved cognitive function (Po0.05). Improvements in BP were related to improved cognitive function in those with SCI (r 2 ¼ 0.52; Po0.05). Impaired NVC, secondary to low BP, may partially mediate reduced cognitive function in individuals with high-level SCI. INTRODUCTIONSpinal cord injury (SCI) is a devastating condition often resulting in disturbed motor, sensory, and autonomic function. As a result of disrupted descending autonomic spinal pathways after SCI, sympathetic vasomotor tone is impaired, often resulting in arterial hypotension. 1 Those with injury at or above T 6 spinal segment, because of a myriad of potential mechanisms (including decentralization of sympathetically mediated vasomotor tone in the splanchnic region and legs) have more profound autonomic disturbances including resting hypotension and orthostatic hypotension as compared with those with lower level SCI. 2 An abundance of evidence, from both animal and human studies, demonstrated that there is an association between low blood pressure (BP) and a variety of cognitive impairments. 3,4 There is well-established evidence that individuals with SCI have a high rate of traumatic brain injury that can result in a significant number of cognitive dysfunctions. 5 However, the high prevalence of cognitive dysfunction (i.e., between 10% and 60%) in SCI 6,7 is likely to be at least partially due to widespread hypotension. 8 This notion is further highlighted by a significant positive relationship between systolic BP (SBP) and cognitive function in the SCI population. 9

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“…180 There is also a significant correlation between the cerebral perfusion pressure (CPP) and PI. 181 In a prospective study, it was shown that TCD ultrasonography is valid in predicting the patient's outcome at 6 months and correlates significantly with ICP and CPP values when it is performed within the first 24 h after severe TBI.…”

Section: Tcd and Intracranial Pressurementioning

confidence: 99%

A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury

Amyot

Arciniegas

et al. 2015

Journal of Neurotrauma

183

147

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The incidence of traumatic brain injury (TBI) in the United States was 3.5 million cases in 2009, according to the Centers for Disease Control and Prevention. It is a contributing factor in 30.5% of injury-related deaths among civilians. Additionally, since 2000, more than 260,000 service members were diagnosed with TBI, with the vast majority classified as mild or concussive (76%). The objective assessment of TBI via imaging is a critical research gap, both in the military and civilian communities. In 2011, the Department of Defense (DoD) prepared a congressional report summarizing the effectiveness of seven neuroimaging modalities (computed tomography [CT], magnetic resonance imaging [MRI], transcranial Doppler [TCD], positron emission tomography, single photon emission computed tomography, electrophysiologic techniques [magnetoencephalography and electroencephalography], and functional near-infrared spectroscopy) to assess the spectrum of TBI from concussion to coma. For this report, neuroimaging experts identified the most relevant peer-reviewed publications and assessed the quality of the literature for each of these imaging technique in the clinical and research settings. Although CT, MRI, and TCD were determined to be the most useful modalities in the clinical setting, no single imaging modality proved sufficient for all patients due to the heterogeneity of TBI. All imaging modalities reviewed demonstrated the potential to emerge as part of future clinical care. This paper describes and updates the results of the DoD report and also expands on the use of angiography in patients with TBI.

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Relationships among cerebral perfusion pressure, autoregulation, and transcranial Doppler waveform: a modeling study

Cited by 78 publications

References 43 publications

Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

Cerebral autoregulation and gas exchange studied using a human cardiopulmonary model

Regional Neurovascular Coupling and Cognitive Performance in Those with Low Blood Pressure Secondary to High-Level Spinal Cord Injury: Improved by Alpha-1 Agonist Midodrine Hydrochloride

A Review of the Effectiveness of Neuroimaging Modalities for the Detection of Traumatic Brain Injury

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