Clinical validation of 40-mm Hg carotid stump pressure for patients undergoing carotid endarterectomy under general anesthesia

BACKGROUND: The aim of this study was to validate a mean stump pressure (SP) of 40 mmHg as the cut off threshold for shunting during carotid endarterectomy (CEA). METHODS: A prospective analysis of recently symptomatic carotid stenosis patients undergoing fast-track CEA under general anesthesia. An arbitrary cut-off threshold of 40 mmHg (mean) was defined as the indication for shunt insertion. With an SP<40 mmHg systemic blood pressure was increased 10-20% using sympathomimetic drugs. Patients with an SP=40 mmHg CEA were operated without a shunt. A neurological observation scheme was filled out preoperatively by the anesthesiologist and postoperatively during the first 24 hours after surgery. Endpoints for validation of SP were per new transient ischemic attack (TIA) or stroke (ipsilateral or contralateral), hypoperfusion/ hypoxia syndrome or death before discharge from hospital. RESULTS: One hundred and twenty consecutive CEAs were performed in recently symptomatic patients. A significant correlation between SP and the contralateral stenosis degree of internal carotid artery (ICA) was found in our study P=0.05. Sixteen patients (14%) had SP<40 mmHg after clamping the carotid arteries. Raising blood pressure intra-operatively by 10-20% reduced the incidence of shunt insertion to only three patients (80% reduction). Of the 120 CEAs, only 2.5% (95% CI 1-6%) of patients required shunt. There was no post-operative TIA or stroke in our study. Two patients (1.65%) suffered early TIA from ipsilateral ICA after discharge from the vascular unit. CONCLUSIONS: Using a mean SP of 40 mmHg as a threshold seems to be a safe, easy and cheap method for selective shunt insertion in fast track CEA under general anesthesia with a zero false-negative rate. Raising the systemic blood pressure by 10-20% during cross clamping increased SP above the threshold value 40 mmHg, thus avoiding shunt insertion in a number of patients.