Significant correlation between cerebral oximetry and carotid stump pressure during carotid endarterectomy

Limited information on a correlation between carotid stump pressure and cerebral oximetry changes associated with cross-clamping of carotid vessels during carotid endarterectomy (CEA) prompted us to prospectively evaluate 38 consecutive CEAs in 37 patients. The authors used the INVOS-4100 cerebral oximeter to measure cerebral oximetry (cerebral oxygen saturation) before (t1) and after (t2) cross-clamping along with carotid stump pressure. All patients had CEA under general anesthesia with the routine use of a Javid shunt. Cross-clamping (t1 vs. t2) resulted in statistically significant changes (p < 0.0001) on the operated side of 6.03 units or a percent change of 9.2% when analyzed using the nonparametric signed-rank test. The nonoperated side had insignificant change (p = 0.71). Spearman correlation analysis revealed significant correlation (r = -0.63) between cerebral oximetry changes on the operated side and carotid stump pressure such that a larger change in cerebral oximetry due to cross-clamping was strongly and significantly correlated with lower carotid stump pressure. Using regression analysis, stump pressures of 25 and 50 mm Hg were predicted by cerebral oximetry changes of 28.5 or 8.8 units, respectively. This is equivalent to a percent change from baseline (t1) of 41.1% or 13.1%, respectively. Taken together, these findings suggest that cerebral oximetry can be used as an alternative to carotid stump pressure to provide noninvasive, inexpensive, and continuous real-time monitoring during CEA.