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).