Selective Internal Carotid Artery Cross-clamping Increases The Specificity Of Cerebral Oximetry For Indication Of Shunting During Carotid Endarterectomy
Aleš Hejcl, M.D., Ph.D., Assoc. Prof., Martin Sameš, prof., M.D., Ph.D..
Masaryk Hospital, Ústí nad Labem, Czech Republic.
OBJECTIVES: An indication for selective shunting during carotid endarterectomy (CEA) is based on monitoring during a procedure. Cerebral oximetry (CO) using near-infrared spectroscopy (NIRS) may be a simple technique but its relevance during CEA, especially with respect to cut off values indicating shunt implantation, still needs to be elucidated.
METHODS: One hundred and twenty five patients underwent CEA under local anesthesia (LA) and were monitored clinically throughout the whole procedure. The patients were also monitored using bilateral NIRS probes during surgery. The NIRS values were recorded and evaluated before and after selective cross-clamping; firstly by the external carotid artery (ECA), followed by the internal carotid artery (ICA). The decrease in the ipsilateral CO values, with respect to the indication of shunting, was only analyzed after selective cross-clamping of the ICA. The decision to use an intraluminal shunt was solely based on the neurological status evaluation after ICA cross-clamping. RESULTS: One hundred and five patients (85%) were stable throughout the CEA, while 20 patients (15%) clinically deteriorated during surgery. The mean drop in the CO after selective ICA clamping in clinically stable patients was 6%, while in patients with clinical deterioration the NIRS decreased by 14.5% (p < 0.05). When the cut-off value for selective shunting was set as a 10% decrease of the ipsilateral CO after selective ICA clamping, the sensitivity of the technique was 100% and the specificity 83.0%. CONCLUSIONS: Our study showed that a 10% decrease in the ipsilateral brain tissue oximetry after selective cross-clamping the ICA, provides a reliable cut-off value for selective shunting during CEA. Despite the availability of a variety of monitoring tools, the NIRS may be an easy, reliable option; especially in the scenario of acute CEA in general anesthesia.
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