Prospective evaluation of electroencephalography, carotid artery stump pressure, and neurologic changes during 314 consecutive carotid endarterectomies performed in awake patients.

OBJECTIVE: This study attempted to correlate neurologic changes in awake patients undergoing carotid endarterectomy (CEA) under cervical block anesthesia (CBA) with electroencephalography (EEG) and measurement of carotid artery stump pressure (SP). METHODS: Continuous EEG and SP monitoring was measured prospectively in 314 consecutive patients undergoing CEA between April 1, 2003, and July 30, 2006, under CBA. Indications for CEA were asymptomatic 70% to 99% internal carotid artery stenosis in 242 (77.1%), transient ischemic attacks (including transient monocular blindness) in 45 (14.3%), and prior stroke in 27 (8.6%). Mean common carotid artery pressure before clamping, mean SP after carotid clamping, and intraarterial pressure were continuously monitored in all patients. An indwelling shunt was placed when neurologic events (contralateral motor weakness, aphasia, loss of consciousness, or seizures) occurred, regardless of SP or EEG changes. RESULTS: Shunt placement was necessary because of neurologic changes in 10% (32/314) of all CEAs performed under CBA. Only 3 patients (1.4%) of 216 required shunt placement if SP was 50 mm Hg or more, vs 29 (29.6%) of 98 if SP was less than 50 mm Hg (P < .00001; sensitivity, 29.8%; specificity, 98.6%). In patients with SP of 40 mm Hg or more, 7 (2.6%) of 270 required shunt placement, vs 25 (56.8%) of 44 if SP was less than 40 mm Hg (P < .00001; sensitivity, 56.8%; specificity, 97.4%). Ischemic EEG changes were observed in 19 (59.4%) of 32 patients (false-negative rate, 40.6%) requiring shunt placement under CBA. Three patients had false-positive EEG results and did not require shunt placement (false-positive rate, 1.0%). The perioperative stroke/death rate was 4 (1.2%) in 314. All strokes occurred after surgery and were unrelated to cerebral ischemia or lack of shunt placement. CONCLUSIONS: Ten percent of patients required a shunt placement during CEA under CBA. Shunt placement was necessary in 56.8% of patients with SP less than 40 mm Hg. EEG identified cerebral ischemia in only 59.4% of patients needing shunt placement, with a false-positive rate of 1.0% and a false-negative rate of 40.6%. Both SP and EEG as a guide to shunt placement have poor sensitivity. Intraoperative monitoring of the awake patients under regional anesthesia (CBA) is the most sensitive and specific method to identify patients requiring shunt placement.

Size and location of thrombus in intact and ruptured abdominal aortic aneurysms.

PURPOSE: This study compared the volume and morphology of intraluminal thrombus (ILT) in intact and ruptured abdominal aortic aneurysms (AAAs). METHODS: ILT volume in 67 intact AAAs and in 31 ruptured AAAs was assessed by using computed tomography (CT) angiography to measure the major and minor diameter of the outer wall and lumen of AAA as outlined by contrast at multiple sites. ILT thrombus morphology was recorded by AutoCAD 2000 software. Four equidistant images traced from the CT scan were recorded along the length of AAA. Thrombus volume was categorized as anterior-eccentric if the calculated area of thrombus was greater anteriorly, posterior-eccentric if greater posteriorly, eccentric-equal if the difference between the anterior and posterior thrombus was

Relationship of residual intraluminal to intrathrombotic pressure in a closed aneurysmal sac.

PURPOSE: This study was undertaken to determine the relationship of residual intraluminal aneurysmal sac pressure (ILASP) to intrathrombic aneurysm sac pressure (ITASP) and to define the relationship between abdominal aorta aneurysm (AAA) size (anteroposterior or transverse diameter), volume of intraluminal thrombus, and residual ITASP. METHODS: We measured ILASP and ITASP after proximal aortic neck and distal iliac clamping by placing angiocatheters into the lumen and thrombus of an excluded aneurysm sac in 41 consecutive patients. Simultaneously, mean blood pressure was recorded and aneurysm sac pressure ratio was calculated. Changes in ILASP and ITASP after clamping of the inferior mesenteric artery were recorded. In addition, correlation between AAA size, volume of intraluminal thrombus in AAA, and residual ITASP was determined. RESULTS: Mean ILASP/blood pressure ratio was 0.40 (SD, 0.20). Mean ITASP/blood pressure ratio was 0.37 (SD, 0.23). There was a significant positive correlation of 0.47 between ITASP and ILASP (P =.002). Clamping of the inferior mesenteric artery resulted in markedly decreased ITASP in 2 patients (n = 40) and ILASP in 4 patients (n = 41). Each centimeter increase in AAA size resulted in a 47 mL increase in thrombus volume. CONCLUSION: Increased ILASP results in corresponding increase in ITASP, and increased AAA size is associated with increased thrombus volume. However, neither thrombus volume nor AAA size has any relationship to ITASP.