Thiopentone Cerebral Protection under EEG Control during Carotid Endarterectomy

Abstract

Seventy patients who underwent a total of 77 consecutive carotid endarterectomies were given thiopentone (mean dose 19 mg/kg) under EEG control for cerebral protection during the period of carotid clamping. This technique was used instead of elective insertion of a temporary bypass shunt in response to adverse EEG changes occurring after clamping. The EEG was monitored continuously throughout operation. The EEG burst-suppression pattern with electrically inactive periods of 30-60 seconds was taken as indicating a depth of barbiturate anaesthesia adequate to provide brain protection. Patients exhibited a drop in blood pressure during barbiturate administration: in most the pressure recovered spontaneously but in twenty operations metaraminol was needed to re-establish an adequate pressure before clamping. No adverse cardiological effects were associated with the administration of thiopentone or metaraminol. There was no mortality and no neurological morbidity in this series.

Thiopental sodium cerebral protection during carotid endarterectomy: Perioperative disease and death

“…High-dose Pentothal was administered to produce burst-suppression, and operation was completed in all seven patients without neurologic deficit. Hicks et al 2 a morbidity and mortality rate of 1.5% in 200 operations.…”

“…9 ,10 Kassel et allO demonstrated that Pentothal, titrated against continuous electroencephalographic recording in doses sufficient to produce maximum reduction in cerebral blood flow and metabolism without cardiovascular depression, produced burst-suppression activity at 30-to 60-second intervals, the level of burst-suppression we have adopted as the monitor of Pentothal dosage. 2 In the clinical setting of carotid endarterectomy, Gross et al ll reported seven patients in whom ischemic electroencephalographic changes developed with clamping. After adjustment of anesthesia to produce hypertension, clamping again produced ischemic changes.…”

“…Disease classification. The disease patterns in these patients were divided into four subgroups defined according to the status of the contralateral internal carotid artery at the time of endarterectomy, namely, stenosis or complex plaque with (1) contralateral occlusion (46 operations [7.4% J), (2) contralateral stenosis greater than 70% (139 operations [22.4% J), (3) contralateral normal artery or stenosis less than 70% (346 operations [55.7%]), (4) previous contralateral endarterectomy (90 operations [14.5% J). Of the 621 operations 448 (72%) were performed for symptomatic stenosis greater than 70%,155 (25.2%) were performed for symptomatic complex plaque or stenosis varying from 50% to 70%, and 18 (2.8%) were performed for asymptomatic disease.…”

“…All patients were given general anaesthetic during surgery with an oxygennitrous oxide mixture and isofluorane as reported previously. 2 Immediately before clamping, Pentothal was administered intravenously by hand injection, the dose being titrated against both the electroencephalographic recording and the arterial blood pressure, monitored via an intraarterial catheter in the radial artery. Pentothal was given until the electroencephalogram showed burst-suppression activity with bursts of activity occurring at intervals of 30 to 60 seconds.…”

Are there commonalities among audit tools used to measure carotid endarterectomy outcomes in New South Wales?

“…However, an audit in South Australia ( n = 223 patients) showed that CEA was not associated with a decrease in the incidence of stroke and death at 12 months as anticipated 9 . Individual Australian vascular units also have reported CEA data 10–31 . In preparation for a state‐wide audit, we conducted a telephone survey of all vascular surgeons within NSW in order to determine pre‐existing CEA audit practices.…”