Abstract
Intraoperative monitoring of electroencephalograms (EEGs) is becoming more commonplace as the technology advances,
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making it easier and less costly to apply.
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Although the cardiovascular status and systemic perfusion are routinely monitored during anesthesia, the brain, which is the target organ of general anesthesia, is generally not monitored. Instead, it is generally assumed that without prior known pathology, adequate cerebral perfusion can be assumed by maintaining adequate mean arterial pressure.
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Cerebral blood flow is not only dependent on adequate cerebral perfusion pressure, which is decreased by elevations in intracranial pressure, but also by changes in cerebral vascular resistance and cerebral vascular pathology.
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Monitoring for cerebral perfusion, however, is not the only application for intraoperative EEG monitoring. EEG can also be used to monitor the depth of sedation and the degree of burst suppression produced by barbiturate infusion, as well as monitoring for the occurrence of seizures while the patients are under the influence of muscle relaxants.
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Each of these applications are discussed in this article, but for intraoperative EEG to be most effectively applied, a number of fundamental principles must first be addressed.