Medicine and Health Sciences Commons^™

Assessing The Sensitivity Of Cerebral Blood Flow And Oxygenation To High Intracranial Pressure With Near-Infrared Light, Sule Karagulleoglu Kunduraci

Electronic Thesis and Dissertation Repository

Premature birth is associated with increased susceptibility to cerebral injuries because of the compounded effects of underdeveloped cerebral vascular and unstable hemodynamics. Notably, premature infants are highly vulnerable to intraventricular hemorrhage, which often leads to hydrocephalus and subsequently to high intracranial pressure (ICP). Current monitoring methods such as ultrasonography can only detect injuries that have already occurred, highlighting the need for prognostic tools. We hypothesize that concomitant measures of cerebral blood flow (CBF), blood oxygenation, and oxygen metabolism will be sensitive to high ICP. To test this hypothesis, experiments were conducted in a piglet model of high ICP using a …

Improving The Reliability And Accessibility Of Ct Perfusion Imaging In Acute Ischemic Stroke, Kevin J. Chung

Electronic Thesis and Dissertation Repository

CT perfusion (CTP) imaging is a validated treatment decision support tool in acute ischemic stroke. Automated analysis of CTP cerebral blood flow (CBF) and Tmax maps produces estimates of ischemic core and penumbra volumes used to determine target mismatch profiles for treatment. However, availability and utilization of CTP is low due to diagnostic variability between CTP software and technical, logistical, and radiation dose considerations that may limit its routine adoption. The objective of this doctoral research was to improve the reliability and accessibility of CTP by (1) improving diagnostic agreement between CTP software, (2) enabling perfusion imaging with standard acute …

Atrial Fibrillation And Cognitive Decline: A Computational Hemodynamics Investigation, Timothy J. Hunter

Electronic Thesis and Dissertation Repository

Background: Atrial fibrillation (AF) is a prevalent cardiac disease which has been associated with increased risk of dementia and cognitive decline. We hypothesize that atrial fibrillation leads to regional transient hypoperfusion events in the brain, and that geometric variations in the arterial structure called the Circle of Willis (CoW) play a role in these events.

Methods: A computational model was developed to simulate cerebral blood flow in six common variations of the CoW. Risk was assessed based on frequency of beat-wise regional hypoperfusion events during AF, and sensitivity analysis was performed with respect to this model output.

Results …

Impact Of Graded Passive Cycling On Hemodynamics, Cerebral Blood Flow, And Heart Function In Healthy Adults And Septic Icu Patients, Jennifer Chen

Electronic Thesis and Dissertation Repository

Sepsis is a life-threatening dysregulation of host response to an infectious insult, which often leads to multi-organ failure. Sepsis survivors suffer from post-intensive care syndrome in part due to their prolonged bed rest and lack of mobility. Although early mobilization has been championed as a mechanism to counter the adverse effects associated with ICU immobility, due to sedation and mechanical ventilation, active early mobilization is not often administered in septic patients due to worries of hemodynamic instability and potential for inducing adverse events. Passive exercise is a mobilization modality that circumvents the need for patients to be conscious and participatory …

Quantification Of Cerebral Blood Flow And Oxidative Metabolism In Infants With Post-Hemorrhagic Ventricular Dilatation, Peter Mclachlan

Electronic Thesis and Dissertation Repository

Post-hemorrhagic ventricular dilatation (PHVD) is highly predictive of mortality and morbidity among very low birth weight preterm infants. Impaired cerebral blood flow (CBF) due to elevated intracranial pressure (ICP) is believed to be a contributing factor. In this study, a hyperspectral near-infrared spectroscopy (NIRS) method of measuring CBF and the cerebral metabolic rate of oxygen (CMRO₂) was used to investigate perfusion and metabolism changes in patients receiving a ventricular tap (VT) based on clinical signs of elevated ICP. To improve measurement accuracy, the spectral analysis was modified to account for compression of the cortical mantle caused by PHVD …

Mapping The Impact And Plasticity Of Cortical-Cardiovascular Interactions In Vascular Disease Using Structural And Functional Mri, Udunna C. Anazodo

Electronic Thesis and Dissertation Repository

There is growing interest in the role of vascular disease in accelerating age-related decline in cerebrovascular structural and functional integrity. Since an increased number of older adults are surviving chronic diseases, of which cardiovascular disease (CVD) is prevalent, there is an urgent need to understand relationships between cardiovascular dysfunction and brain health. It is unclear if CVD puts the brains of older adults, already experiencing natural brain aging, at greater risk for degeneration. In this thesis, the role of CVD in accelerating brain aging is explored. Because physical activity is known to provide neuroprotective benefits to brains of older adults, …

Improving Acute Stroke Management With Ct Perfusion Imaging: Approaches To Treatment Guidance And Brain Tissue Salvage, Christopher D. D'Esterre

Electronic Thesis and Dissertation Repository

CT Perfusion (CTP) provides measurement of perfusion at the capillary level which can be used to characterize tissue viability, and blood-brain-barrier (BBB) compromise. Using CTP, the goals of this research are to: 1) select patients that will benefit from acute stroke treatment, and 2) determine if pre-stroke neuroprotection reduces stroke severity.

Chapter two investigates the cerebral blood volume (CBV) parameter in a small acute ischemic stroke (AIS) patient set. Overestimation of the acute CBV defect is caused by incomplete wash-out of the CT contrast due to a shortened CTP acquisition time (“truncation artifact”).

In chapter three we examine the prognostic …

Investigating Adenosine’S Role In Controlling The Cerebral Metabolic Rate Of Oxygen Following Hypoxia-Ischemia, Mustafa Ridha

Electronic Thesis and Dissertation Repository

The cerebral metabolic rate of oxygen (CMRO2) has been shown to be an early indicator of hypoxia-ischemia (HI); however, the mechanisms controlling post-HI CMRO2 are not clear. One potential mechanism is the activation of the adenosine A1 receptor due to increased adenosine concentrations during the insult. The present study investigated if the specific adenosine A1 antagonist, DPCPX, would reduce the typical reduction in CMRO2 and electrical cortical activity following HI. Measurements of CMRO2 and electrical cortical activity were obtained on piglets by near-infrared spectroscopy (NIRS) and amplitude-integrated electroencephalography (aEEG), respectively. The post-HI measurements of CMRO2 and mean aEEG background voltage …