A prophylactic bolus of thiopentone does not protect against prolonged focal cerebral ischaemia.

Barbiturate coma is still recommended for brain protection during periods of temporary focal ischaemia such as during carotid endarterectomy. We tested the hypothesis that a single dose of barbiturate given before a period of protracted severe focal ischaemia would protect against focal cerebral infarction. Sixteen cats had the proximal left middle cerebral artery (MCA) occluded. Eight cats received halothane alone titrated to keep their pulse and blood pressure within the normal range. Eight cats received, in addition to halothane, a bolus of thiopentone sufficient to produce an isoelectric EEG immediately prior to MCA occlusion. Six hours after the occlusions the animals were sacrificed and the brains scored histologically to assess both size and severity of ischaemia. There was no statistically significant difference in the size or severity of the infarcts between the groups. We conclude from this study that the extent of the histological injury was not reduced by a single prophylactic bolus of thiopentone given before prolonged focal cerebral ischaemia.