Isoflurane: effect on the encephalogram during carotid endarterectomy.

The effect of isoflurane on the electroencephalogram was studied in patients monitored during carotid endarterectomy. Increasing concentrations of this agent cause changes, but did not affect the ability to detect the onset of cerebral ischaemia consequent upon temporary occlusion of the internal carotid artery. At 1.0% and 1.5% concentration isoflurane caused significant decreases in mean arterial pressure which is undesirable in patients undergoing vascular surgery.