Near Infrared Spectroscopy For Cerebral Hemodynamic Monitoring During Carotid Endarterectomy Under General Anesthesia

Background: Near infrared spectroscopy (NIRS) is a noninvasive method for continuous monitoring of cerebral oxygenation. Objective: To describe the intraoperative behavior of NIRS variables used to evaluate hemodynamic response in patients with atherosclerotic disease undergoing carotid endarterectomy under general anesthesia. Methods: Fifteen volunteers with atherosclerotic carotid disease with indications for endarterectomy were evaluated. After selection of patients, carotid stenosis was confirmed by appropriate diagnostic methods. NIRS was used for intraoperative monitoring. The variables total hemoglobin (Hb), oxygenated hemoglobin (O(2)Hb), deoxygenated hemoglobin (HHb), and regional oxygen saturation (rSO(2)) were evaluated at three intraoperative time points: before, during, and after carotid clamping. Results and Discussion: Measurements recorded by NIRS showed that, during the first 5 min of clamp time, patients experienced a decline in O(2)Hb levels, an increase in HHb levels, and a marked decrease in rSO(2). Hb remained constant throughout the procedure. At the post-clamping time point, HHb, O(2)Hb, and rSO(2) returned to patterns similar to those observed before clamping. Conclusion: NIRS was able to reliably and accurately identify the three stages of carotid endarterectomy and may predict the risk of cerebral hypoxia during carotid clamping under general anesthesia.