Cerebral Blood Flow Measurement as a Safeguard During Carotid Endarterectomy

Abstract

Intraoperative measurement of regional cerebral blood flow (rCBF) by the 133 Xe intracarotid injection technique was performed in 17 patients operated on for stenosis of the internal carotid artery. Mean rCBF decreased from 51 ml/100 gm x minute before endarterectomy to 30 ml/100 gm x minute when the internal carotid artery was clamped, a reduction of 41%. Postoperative aggravation of neurological deficits was observed in five patients in whom rCBF was at or below 30 ml/100 gm x minute during the period of carotid clamping, indicating a critical lower limit of rCBF of this magnitude. Flow reduction below this limit was tolerated only if the occlusion time was short. A critical time/flow relation is suggested. Distal internal carotid artery blood pressure during clamping (measured in eight cases) was poorly correlated to rCBF (r = 0.62, 0.1 > P > 0.05).