NEAR-INFRARED REFLECTED SPECTROSCOPY AND ELECTROENCEPHALOGRAPHY DURING CAROTID ENDARTERECTOMY - IN SEARCH OF A NEW SHUNT CRITERION

The aim of this clinical study was to evaluate cerebral oximetry with near-infrared reflected spectroscopy (NIRS) as a monitoring system dur ing carotid endarterectomy. The cross-clamping changes of cerebrovascu lar hemoglobin oxygen saturation (cereb. O-2 satn.) were compared with data from a processed EEG analysis. Using the EEG as the gold standar d lye try to define a new shunt criterion based on near-infrared spect roscopy. 102 patients were studied. During cross-clamping the percentu al decrease of cereb. O-2 satn. was calculated. The relation between E EG and cereb. O-2 satn. is described in terms of sensitivity and speci ficity and is graphically shown in a Receiver Operator Characteristic (ROC) curve. At a cut-off value of 5% decrease or more for the cereb. O-2 satn., a sensitivity of 100% was found. However, the specificity w as only 44%. Higher cut-off values resulted in a gradual increase of t he specificity at the expense of a significant decrease of the sensiti vity. In conclusion, improved validation and calibration techniques ar e necessary before this technique may be used for relevant assessment of cerebral oxygenation during carotid surgery. In particular, in orde r to define a new shunt criterion, the focal aspect of this new techni que is probably one of the limitations.