Clinical Neurologic Issues in Cerebrovascular Monitoring

Cerebral blood flow is normally matched to substrate demand; this process of autoregulation is disrupted in many disease states, and often results in secondary ischemic damage that impairs outcome beyond the effects of an initial insult. Cerebral perfusion pressure, the difference between mean arterial pressure and intracranial pressure, is the most commonly measured parameter employed in the management of patients with increased intracranial pressure. More recent techniques, including brain tissue oxygen measurement and microdialysis, increase our ability to detect evidence of cerebral ischemia. Management of patients with such ischemia, or in danger of developing it, has classically depended on raising mean arterial pressure or lowering intracranial pressure. Newer treatments add ways of improving oxygen delivery to ischemic tissue in the hope of minimizing secondary injury.