Prediction of cerebral ischaemia during carotid endarterectomy with preoperative CO 2 -reactivity studies and angiography

Abstract

The objective of this study was to assess the value of combining the preoperative CO 2 cerebrovascular reactivity index (CO 2 RI) with carotid and cerebral angiography in predicting the risk of severe cerebral ischaemia (SCI) during carotid endarterectomy (CEA). Seventy-four consecutive patients scheduled for CEA underwent preoperative digital subtraction angiography and CO 2 -reactivity tests. During CEA, cerebral function monitor (CFM) was used to document cortical electrical activity, whilst transcranial Doppler measured the middle cerebral artery flow velocity (FV). A persistent fall in CFM voltage and/or a fall in FV S 60% on internal carotid artery (ICA) clamping were used as criteria for defining SCI. Complete data from 59 patients were obtained for final analysis. Twelve cases showed a fall in FV S 60%; 11 of these also showed a sustained fall in CFM voltage. Using logistic regression, the risk of SCI was found to be negatively associated with (1) contralateral CO 2 RI, (2) the percentage stenosis of the contralateral ICA, and (3) the difference between ipsilateral and contralateral CO 2 RI. Using these factors, a logistic regression model for predicting the risk of SCI was established which provided a sensitivity of 75% and specificity of 100%. The risk of SCI during CEA was related to the contralateral ICA stenosis and the CO 2 RI of both cerebral hemispheres. This information may assist in presurgical planning and help to select asymptomatic carotid lesions for surgery.

• Carbon Dioxide Reactivity Carotid Endarterectomy Carotid Occlusive Disease Cerebral Haemodynamics Cerebral Ischaemia Transcranial Doppler