The Effect of Barbiturate in Brain Protection under Mild Hypothermia During Temporary Vessel Occlusion in Aneurysm Surgery

ABSTRACT

Temporary vessel occulusion is a useful technique which facilitates aneurysmal dissection and clipping, and reduces the risk of intraoperative aneurysal rupture; It may, however, result in postoperative stroke, and many authors have therefore used various agents for brain protection. Among these, barbiturate is well known. This study was undertaken to retrospectively review the effect of barbiturate on brain protection during short periods of ischemia. It involved patients with 146 anterior circulation aneurysms, who were divided into two groups 43 who received intraoperative barbiturate burst suppression with sodium thiopental during temporary vessel occlusion and the remaining 103, who did not. Doses of thiopental 5mg/kg, usually singly or occasionally repeated at 10-mimute interval, were administered. All patients underwent general anesthesia using volatile isoflurane; mild hypothermia(32-34degreesC), mild hypocarbia(30-35mmHg), and normotension of 110-130mmHg were noted prior to permanent clipping, and mild hypertension(130-150mmHg) after clipping. In some cases, intraoperative scalp electroencep-halography was monitored. Clinical, radiological, and overall infarction were assessed postoperatively, and statistical analysis was perfomed. With regard to Hunt-Hess grades, number of episodes of occlusion, duration of temporary clip application lasting less than 13 minutes, and period of post-subarachnoid hemorrhage, no significant differences were seen between the two groups. Patients in whom barbiturate burst was suppressed showed a 4-hours delay in mean anesthetic recovery time, and after thiopental sodium was injected intravenously, systolic and mean arterial pressure(MAP), averaging 10-20mmHg, were lowered than in those without this suppression. In conclusion, we had found that under mild hypothermic anesthesia involving less than 13 minutes of temporary vessel occlusion, protection of the brain by barbiturate was not beneficial.