HEMODYNAMIC ISCHEMIC STROKE DURING CAROTID ENDARTERECTOMY - AN APPRAISAL OF RISK AND CEREBRAL PROTECTION

Purpose: The purpose of this study was to validate the commonly accept ed indicators of risk of ischemic stroke that indicate the necessity f or cerebral protection during carotid endarterectomy (CEA), and to exa mine the efficacy of high-dose thiopentone sodium (thiopental) as a ce rebral protection method in patients who are at high risk of intraoper ative ischemic stroke. Method: In a prospective study of 37 CEAs pet-f ormed for symptomatic stenosis >70%, functional and clinical indicator s of risk of ischemic stroke during carotid cross-clamping were identi fied. Functional indicators of risk were the development of ischemic e lectroencephalogram (EEG) changes and stump pressure <25 mm Hg. Clinic al indicators of risk were previous ischemic hemispheric stroke and se vere bilateral disease. These indicators were correlated in all patien ts, some of whom had two or three coexisting indicators of risk. The E EG and stump pressure were monitored continuously during carotid occlu sion in all operations. Carotid occlusion times were recorded. Intralu minal shunting was eliminated in favor of high-dose thiopental cerebra l protection in all patients. Neurologic outcome was deemed to measure the efficacy of thiopental protection in patients who are identified to be at risk and, hence, in need of cerebral protection. The validity of the indicators used to identify risk of ischemic stroke during CEA was assessed. Results: The absolute stroke risk was found to be 29.7% for the whole group (37 patients) and 57.9% in 19 patients who had co mmonly accepted indications for protective shunting. The correlation o f ischemic EEG changes with stump pressure <25 mm Hg was only 27.3%, w hereas the expected correlation based on well-documented reports in th e literature was 100%. The lack of correlation may have been related t o the prevention of ischemic EEG changes by thiopental. There were no neurologic deficits in the series. Conclusions: The absence of neurolo gic deficit in the study indicated that thiopental protection was effe ctive in preventing ischemic stroke in high-risk patients and safely r eplaced intraluminal shunting.