The Lifescan™ EEG Monitor for Detection of Cerebral Ischemia in Carotid Endarterectomy: Case Reports, Prospective Study of Comparison Between Lifescan™ and Somatosensory Evoked Potential (SEP)
It is very difficult for anesthesiologists to assess cerebral well being during carotid endarterectomy. It has become important to evaluate and prevent cerebral ischemia by effective monitoring equipments. It has been reported that post-operative stroke is not uncommon and its rate is from 0.6% to 3.0% during carotid endarterectomy (1), and occurrence of EEG ischemic changes is more often and its rate is from 15% to 25% (2). For these reasons, there are several CNS monitoring which are available in the operating room today. There are Electroencephalography (EEG), (the Lifescan is included in this category), Somatosensory Evoked Potential (SEP), Cerebral Blood Flow (CBF), and Stump pressure. It has become important to evaluate which monitoring equipment is most effective for detecting ischemia during carotid endarterectomy. It has been repotted that ischemic changes of EEG have a high correlation with CBF(3). It is called critical regional CBF when EEG ischemic changes occurs, and critical CBF is from 18 to 20 ml/100 g/min in halothane anesthesia (3), 15 ml/100 g/min in enflurane anesthesia, and 10 ml/100 g/min in isoflurane anesthesia. We believe that it is reasonable to monitor EEG to detect and prevent ischemia by this reason. The Lifescan used aperiodic analysis for quantifying each EEG wave form, and maps each wave form in relation to its frequency, amplitude, and time of occurrence (4). Aperiodic analyzed each wave form are displayed within three dimensional box as color vectors, and as time advances, the display moves upward from the bottom of the box. Left box represents left hemisphere and right box represents right hemisphere.
KeywordsCerebral Blood Flow Cerebral Ischemia Carotid Endarterectomy Carotid Artery Stenosis Somatosensory Evoke Potential
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