Physiological Determinants of RCBF and RCBV

Increases in local neuronal activity are accompanied by increases in regional cerebral metabolic rate (rCMR). Until recently, the increases in rCBF and oxygen consumption produced during such functional activation were thought to be closely coupled to the cerebral metabolic rate of utilization of O2 (CMRO2) and glucose (CMRglu). However, it has now been clearly shown that increases in rCBF during functional activation tend to track glucose utilization but may be far in excess of the increase in...

Cbf1620

Intracranial pathology may affect the reliability of TCD as a measure of CBF. Cerebral vasospasm, space-occupying lesions and increases in intracranial pressure (ICP) may affect the accuracy of FV measurements.2021 A complete diagnostic examination of the cerebral circulation will usually utilize the transtemporal approach through the thin bone above the zygomatic A plot of the increase in flow velocity in the middle cerebral artery (Vmca) versus the increase in cerebral blood flow equivalent...

Excitatory Amino Acid Antagonists

To date, approximately 19 agents that block EAA receptors have been shown to be effective in a variety of experimental brain injury models.60 Non- competitive NMDA channel antagonists such as dizolcipine (MK-801) have a theoretical advantage over competitive agents such as CGS 19755, in that competitive antagonism may be overcome by the pathologically high concentrations of glutamate associated with cerebral ischaemia.66 These two agents have proved particularly encouraging as...

Nirs

Continuous neurological assessment Avoids the risks of general anaesthesia Lower incidence of postoperative hypertension Shorter ICU stay Easier to use than 16 channel Less cumbersome set-up Measures retrograde perfusion pressure Requires patient cooperation, ability to lie flat, anxiety, hyperventilation with potential risk of cerebral ischaemia, risk of autonomic disturbances, nausea, vomiting and airway obstruction Cumbersome, difficult to interpret Not suitable for theatre environment More...

Pco

276 and are increasingly being implanted into brain tissue to continuously monitor tissue CO2' pH, PO2 and temperature.77 78 The effects of temporary focal ischaemia, hypoventilation and anaesthetic drugs on brain parenchyma PO2 PCO2 and pH are being evaluated. Initial reports suggest the changes to be reliable and reproducible.79 80 Reported brain tissue PO2 values in patients who have suffered a severe head injury are similar to those obtained using the Licox sensor. Furthermore, it appears...

Management of Guillain Barre Syndrome on the Intensive Care Unit

Between 10 and 33 of patients with acute inflammatory demyelinating polyneuropathy will need admission to an intensive care unit.4142 This is predominantly to manage respiratory failure, although bulbar weakness, dysautonomia, sepsis and hypotension are also indications for admission. Ropper et al have made a careful clinical study of Guillain-Barre syndrome and highlight oropharyngeal weakness, as well as weakness of shoulder elevation and neck flexion, as harbingers of impending respiratory...

Info

Example of recording of intracranial pressure (ICP) and arterial blood pressure (ABP) in patient following head injury with low and well-stabilized ICP. is commonly seen in the first 6-8 h after head injury in those with CT scan showing no space-occupying lesions with little or no swelling and is usually associated with good outcome. Mean ICP > 20 mmHg that is stable with very limited expression of the slow vasogenic waves are the hallmarks of this pattern (Fig. 7.2). The presence of this...

Monitoring The Central Nervous System

Electrophysiological Monitoring of the Central Nervous System Brian McNamara & Simon J. Boniface Evoked Potentials in Normal Subjects 71 The EEG and General Anaesthetics 73 Preoperative Assessment in Epilepsy Surgery 75 Neurophysiological Monitoring and Intraoperative Care 76 Electrophysiological Monitoring in the Intensive Care Unit 77 The EEG in Status Epilepticus 79 Neurophysiology and Predicting Outcome 80 The techniques of clinical neurophysiology provide a non-invasive and inexpensive...

Intraoperative Management Of Neurosurgical Patients

Some General Considerations in Neuroanaesthesia The anaesthetist in the operating theatre must endeavour to provide good intracranial operating conditions. This means ensuring that the intracranial pressure (ICP) does not rise and that, when the skull is open, brain bulk is not increased. The neurosurgeon must be able to retract the brain easily too high a pressure on the retractors may result in neuronal damage. Understanding the mechanisms underlying the alterations in ICP in disease, the...