Predicting clinical ischaemia during awake carotid endarterectomy: use of the SJVO2 probe as a guide to selective shunting

Stroke is a major cause of disability within the western world. About 20% of strokes are a consequence of atheromatous narrowing of the origin of the internal carotid artery. Carotid endarterectomy has been shown to be an effective treatment for those with symptomatic and severe stenosis, provided the risk of death and peri-operative stroke is less than 7%. The aim of this study was to investigate the clinical value of jugular venous oxygen saturation (SJVO2) monitoring in identifying patients who develop cerebral ischaemia whilst undergoing an awake carotid endarterectomy by comparison with a simple neurological assessment. Each patient underwent a standard awake carotid endarterectomy. Per-operatively a SJVO2 catheter was inserted, and the jugular oxygen saturation was correlated with the presence or absence of cerebral ischaemia. Data from 34 patients were analysed using time-series plots and by calculating a receiver operator characteristic (ROC) curve. The optimal sensitivity and specificity for this technique were found to be 1.0 and 0.8, respectively, when a 25% change in SJVO2 was used as a threshold. Although a small observational study, we have shown that percentage change in SJVO2 correlates well with the development of clinically apparent cerebral ischaemia. This technique may improve the safety of carotid endarterectomy under general anaesthesia when used with other more established monitoring methods.