16. EEG monitoring to measure cortical activity during carotid endarterectomies. What have we learned in the last 33 years?

Abstract

EEG changes during carotid endarterectomy (CE) are well known for several decades. Frequent blood pressure changes (BP) are linked to EEG changes during different phases of surgery. Patients for carotid surgery have a mean age of 73 years and from 2 to 4 vascular risk factors. We observed 5 phases in almost all patients. Phase 1 (pre-anesthesia). In general, the patients present a moderate hypertension. It is a frequent mistake to treat this hypertension with drugs that are difficult to reverse later during surgery. Phase 2 (from the start of the anesthesia to carotid clamping test). Intense surgical stimulus tend to increase BP. We must avoid the hypotension caused by an strong pharmacological treatment at this time. This phase lasts between 20 and 40 min. Phase 3 (clamping test). It must be performed under normal or slightly elevated BP. Phase 4 (endarterectomy), during this stage, the surgical stimulus is minimal and patients tend to hypotension. It is crucial to maintain BP values very similar to those observed during clamping test. Phase 5 (post-endarterectomy to the awake). A strong surgical stimulation were observed during surgical closure. The patient tends to hypertension with risk bleeding and arterial suture failure. At this time, BP must be quickly normalized. Knowledge of these phases avoids false positives, unnecessary alarms and unnecessary arterial shunt placement.