Extracellular brain pH with or without hypoxia is a marker of profound metabolic derangement and increased mortality after traumatic brain injury.

Cerebral hypoxia and acidosis can follow traumatic brain injury (TBI) and are associated with increased mortality. This study aimed to evaluate a relationship between reduced pH(bt) and disturbances of cerebral metabolism. Prospective data from 56 patients with TBI, receiving microdialysis and Neurotrend monitoring, were analyzed.

Interaction between brain chemistry and physiology after traumatic brain injury: impact of autoregulation and microdialysis catheter location.

Bedside monitoring of cerebral metabolism in traumatic brain injury (TBI) with microdialysis is gaining wider clinical acceptance. The objective of this study was to examine the relationship between the fundamental physiological neuromonitoring modalities intracranial pressure (ICP), cerebral perfusion pressure (CPP), brain tissue oxygen (P(bt)O(2)), and cerebrovascular pressure reactivity index (PRx), and cerebral chemistry assessed with microdialysis, with particular focus on the lactate/pyruvate (LP) ratio as a marker of energy metabolism. Prospectively collected observational neuromonitoring data from 97 patients with TBI, requiring neurointensive care management and invasive cerebral monitoring, were analyzed.

Cerebral extracellular chemistry and outcome following traumatic brain injury: a microdialysis study of 223 patients.

Secondary insults can adversely influence outcome following severe traumatic brain injury. Monitoring of cerebral extracellular chemistry with microdialysis has the potential for early detection of metabolic derangements associated with such events. The objective of this study was to determine the relationship between the fundamental biochemical markers and neurological outcome in a large cohort of patients with traumatic brain injury.

Improved cerebrovascular reactivity following low flow EC/IC bypass in patients with occlusive carotid disease.

Patients with major cerebral artery occlusive disease can suffer cerebral hypoperfusion and be at an increased risk of future strokes. EC/IC bypass has been shown to reduce this risk. Patients with cerebral hypoperfusion, and who are at risk of haemodynamic ischaemia, can be identified by the use of xenon computerised tomography (XeCT) to demonstrate severe impairment of the cerebrovascular reserve (CVR).

Hypertonic saline in patients with poor-grade subarachnoid hemorrhage improves cerebral blood flow, brain tissue oxygen, and pH.

Background And Purpose: Delayed cerebral ischemia and infarction due to reduced CBF remains the leading cause of poor outcome after aneurysmal subarachnoid hemorrhage. Hypertonic saline (HS) is associated with an increase in CBF. This study explores whether CBF enhancement with HS in patients with poor-grade subarachnoid hemorrhage is associated with improved cerebral tissue oxygenation.

A combined microdialysis and FDG-PET study of glucose metabolism in head injury.

Background: Microdialysis continuously monitors the chemistry of a small focal volume of the cerebral extracellular space. Positron emission tomography (PET) establishes metabolism of the whole brain but only for the scan's duration. This study's objective was to apply these techniques together, in patients with traumatic brain injury, to assess the relationship between microdialysis (extracellular glucose, lactate, pyruvate, and the lactate/pyruvate (L/P) ratio as a marker of anaerobic metabolism) and PET parameters of glucose metabolism using the glucose analogue [(18)F]-fluorodeoxyglucose (FDG).

Nitric oxide in acute brain injury: a pilot study of NO(x) concentrations in human brain microdialysates and their relationship with energy metabolism.

Introduction: This pilot microdialysis study in acute brain injury patients assessed the relationship between nitric oxide products (total nitrite plus nitrate, termed NO(x)) and energy-related molecules: glucose, lactate, pyruvate, glutamate and glycerol.

Methods: Twelve patients (11 major head-injury and one subarachnoid haemorrhage) were studied, 11 of which had single catheters and one had two catheters, in the cerebral cortex. Catheters were perfused at 0.

Ventriculostomy for control of raised ICP in acute traumatic brain injury.

Unlabelled: The aim of this study was to evaluate the effect of ventriculostomy on intracranial pressure (ICP), and related parameters, including cerebrospinal compensation, cerebral oxygenation (PbtO2) and metabolism (microdialysis) in patients with traumatic brain injury (TBI).

Materials And Methods: Twenty-four patients with parenchymal ICP sensors were prospectively included in the study. Ventriculostomy was performed after failure to control ICP with initial measures.

Inflammation in human brain injury: intracerebral concentrations of IL-1alpha, IL-1beta, and their endogenous inhibitor IL-1ra.

Following traumatic brain injury (TBI), cascades of inflammatory processes occur. Laboratory studies implicate the cytokines interleukin-1alpha (IL-1alpha) and IL-1beta in the pathophysiology of TBI and cerebral ischemia, whilst exogenous and endogenous interleukin-1 receptor antagonist (IL-1ra) is neuroprotective. We analyzed IL-1alpha, IL-1beta, and IL-1ra in brain microdialysates (100-kDa membrane) in 15 TBI patients.

Enhancement of cerebral blood flow using systemic hypertonic saline therapy improves outcome in patients with poor-grade spontaneous subarachnoid hemorrhage.

Object: Systemic administration of 23.5% hypertonic saline enhances cerebral blood flow (CBF) in patients with poor-grade spontaneous subarachnoid hemorrhage (SAH). Whether the increment of change in CBF correlates with changes in autoregulation of CBF or outcome at discharge remains unknown.

Microdialysis in the management of hepatic encephalopathy.

Introduction: Fulminant hepatic encephalopathy has a high mortality.

Methods: This case report describes the role of cerebral microdialysis as an adjunct to the management of a 49 - year-old woman with hepatic encephalopathy secondary to a paracetamol overdose.

Results: The application of the microdialysis technique, by detecting a very low cerebral glucose concentration in the presence of a normal plasma glucose, assisted in clinical decision making.

A randomized trial of synthetic patch versus direct primary closure in carotid endarterectomy.

Objective: To define whether or not direct microscopic closure with or without the use of a vascular patch is advantageous in terms of clinical outcome and late vessel occlusion rates after microsurgical carotid endarterectomy.

Methods: Three hundred thirty-eight elective carotid endarterectomies in 315 patients were randomized to direct arteriotomy or closure with a polyester collagen-coated vascular patch. Ten procedures did not follow the randomization process because of technical difficulties and were excluded.

Tissue oxygen index: thresholds for cerebral ischemia using near-infrared spectroscopy.

Background And Purpose: To date, the clinical application of near infrared spectroscopy in the adult brain has been limited. The NIRO 300 (Hamamatsu Photonics) provides a continuous measurement of tissue oxygen index (TOI) using spatially resolved spectroscopy. Although TOI reflects cerebral oxygenation to a high degree of sensitivity and specificity, to become a useful clinical tool, thresholds for cerebral ischemia need to be defined.

Near infrared spectroscopy in brain injury: today's perspective.

The technique of near infrared spectroscopy (NIRS) is based on the principle of light attenuation by the chromophores oxyhaemoglobin (HbO2), deoxyhaemoglobin (Hb) and cytochrome oxidase. Changes in the detected light levels can therefore represent changes in concentrations of these chromophores. Clinical use of NIRS in the brain has been well established in neonates where transillumination is possible.

Glucose metabolism in traumatic brain injury: a combined microdialysis and [18F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) study.

Following traumatic brain injury, as a consequence of ionic disturbances and neurochemical cascades, glucose metabolism is affected. [18F]-2-Fluoro-2-deoxy-D-glucose (FDG) Positron Emission Tomography (FDG-PET) provides a measure of global and regional cerebral metabolic rate of glucose (rCMRglc), but only during the time of the scan. Microdialysis monitors energy metabolites over extended time periods, but only in a small focal volume of the brain.

Cerebral blood flow augmentation in patients with severe subarachnoid haemorrhage.

Following aneurysmal subarachnoid haemorrhage (SAH), cerebral blood flow (CBF) may be reduced, resulting in poor outcome due to cerebral ischaemia and subsequent stroke. Hypertonic saline (HS) is known to be effective in reducing intracranial pressure (ICP). We have previously shown a 20-50% increase in CBF in ischaemic regions after intravenous infusion of HS.

Extracellular amino acid changes in patients during reversible cerebral ischaemia.

This study investigated the changes in extracellular chemistry during reversible human cerebral ischaemia. Delayed analysis was performed on samples taken from a subgroup of patients during aneurysm surgery previously reported. Frozen microdialysis samples from 14 patients who had all undergone temporary clipping of the ipsilateral internal carotid artery (ICA) were analysed for another 15 amino acids with HPLC and for glycerol with CMA-600.

Cerebral microdialysis methodology--evaluation of 20 kDa and 100 kDa catheters.

Microdialysis monitoring of cerebral metabolism is now performed in several neuro-intensive care units. Conventional microdialysis utilizes CMA70 catheters with 20 kDa molecular weight cut-off membranes enabling the measurement of small molecules such as glucose, lactate, pyruvate and glutamate. The CMA71 100 kDa molecular weight cut-off microdialysis catheter has recently been introduced to allow detection of larger molecules such as cytokines.

Carotid endarterectomy impairs blood pressure homeostasis by reducing the physiologic baroreflex reserve.

Objective: To assess the impact of carotid endarterectomy on blood pressure homeostasis and baroreflex function, with particular reference to the presence or absence of significant contralateral carotid artery disease, we conducted a prospective study in 80 patients with symptomatic extracranial carotid disease undergoing carotid endarterectomy in a regional teaching hospital over 2 years.

Methods: Patients were divided into two groups: the control group (n = 37) had no significant contralateral carotid disease; patients in the diseased group (n = 23) had either >70% stenosis or occlusion of the contralateral carotid artery. Seventeen patients with abnormal heart rhythms, poor quality recordings, or with intermediate degrees of contralateral carotid stenosis were excluded.

Effect of cerebral perfusion pressure augmentation on regional oxygenation and metabolism after head injury.

Objective: In this study we have used O positron emission tomography, brain tissue oxygen monitoring, and cerebral microdialysis to assess the effects of cerebral perfusion pressure augmentation on regional physiology and metabolism in the setting of traumatic brain injury.

Design: Prospective interventional study.

Setting: Neurosciences critical care unit of a university hospital.

Hyperglycemia and brain tissue pH after traumatic brain injury.

Objective: Hyperglycemia occurring after head injury is associated with poor neurological outcome. We tested the hypothesis that blood glucose levels are associated with brain tissue pH (pH(b)) and that the correction of hyperglycemia would result in an improvement in pH(b).

Methods: This is a retrospective analysis of a prospectively collected database.

Extracellular Brain pH and Outcome following Severe Traumatic Brain Injury.

The ability to measure brain tissue chemistry has led to valuable information regarding pathophysiological changes in patients with traumatic brain injury (TBI). Over the last few years, the focus has been on monitoring changes in brain tissue oxygen to determine thresholds of ischemia that affect outcome. However, the variability of this measurement suggests that it may not be a robust method.

Effect of lignocaine injection in carotid sinus on baroreceptor sensitivity during carotid endarterectomy.

Objectives: This study was undertaken to test the hypothesis that there is a neural basis for baroreceptor deterioration during carotid endarterectomy (CEA), by investigating intraoperative hemodynamic changes induced by intraluminal carotid stretch stimulation, before and after application of local anesthetic to the adventitial layer of the carotid sinus region.

Methods: This was a prospective study of 20 patients undergoing elective CEA. During CEA, before removal of the atheroma, intraluminal stretch simulation of the carotid baroreceptors (rub test) was performed before and after injection of 1% lignocaine into adventitial tissue of the artery in the region of the carotid sinus.

Effect of cerebral perfusion pressure augmentation with dopamine and norepinephrine on global and focal brain oxygenation after traumatic brain injury.

Objective: To compare the effects of a cerebral perfusion pressure (CPP) intervention achieved with dopamine and norepinephrine after severe head injury.

Design: Prospective, controlled, trial.

Setting: Neurosciences critical care unit.