Impact of contralateral carotid stenosis on brain tissue oxygenation during carotid endarterectomy

Background: Cerebral oximetry (rSO(2)) seems to be a promising technique for assessment the adequacy of cerebral oxygen delivery during carotid endarterectomy (CEA). The purpose of this study was to evaluate the association of the severity of contralateral (non-operated) carotid artery stenosis and the magnitude of rSO(2) changes during CEA. Methods: rSO(2) was monitored in 38 patients undergoing CEA under regional anesthesia. Patients were retrospectively assigned to one of two groups: with (Gdef) or without (Gnodef) change in neurological status. Baseline rSO(2) values (rSO(2) base), average (rSO(2)avg) and minimal (rSO(2)min) values during 3 minutes after clamping, and rSO(2) change after clamping (Delta rSO(2)avg and Delta rSO(2)min) were compared between both groups. The influence of contralateral carotid artery stenosis on rSO(2) was assessed by correlation. Data are presented as median (IQR). Results: Neurologic deterioration has developed in 4 patients. We did not find any statistical difference in rSO(2) values between Gdef a Gnodef on operated side - rSO(2) base was 79 (75-87) in Gnodef and 79 (64-90) in Gdef (p = 0.84), rSO(2) min 74 (65-81) in Gnodef and 75 (59-90) in Gdef (p = 0.70), and Delta rSO(2) min 6 (2-13) in Gnodef and 2 (0-6) in Gdef (p = 0.15). Similarly, there was not any difference between groups if rSO(2) was measured on contralateral side. We showed that non-operated ACI stenosis was a risk factor for developing of perioperative neurological deficit, but we did not demonstrate any influence of non-operated ACI stenosis severity on rSO(2) values. Conclusion: We did not prove any association between the severity of contralateral carotid artery stenosis and the magnitude of rSO(2) changes during CEA. Cerebral oximetry was not able to predict the development of neurologic deficit during CEA.