Abstract WP134: Decreased Flow Velocities After General Anesthesia Before Carotid Endarterctomy Are Not Associated with Cerebral Hyperperfusion Syndrome or Perioperative Cerebral Infarction

Abstract

Introduction: Cerebral Hyperperfusion Syndrome (CHS) is a life threatening complication in about 3% of patients following carotid endarterectomy (CEA). There is a concern that baseline flow velocities typically decrease after general anesthesia (GA) may predispose patients to CHS and other perioperative adverse events. Hypothesis: Patients with decreased flow velocity after GA are at increased risk for CHS using ultrasonographic and clinical diagnostic criteria. Methods: We retrospectively evaluated 920 patients who received CEA from 2006 to 2016 at a major hospital in China. Middle cerebral artery blood flow velocities were measured when patients were awake and after induction of the GA. Ultrasonographic diagnostic criterion of CHS was “100% increase in flow velocity by TCD from the baseline to post-CEA”. Patients were classified into two groups: NORMAL group if flow velocity decreased <30% and LOW group if decreased >=30%. The occurrences of CHS by ultrasonongraphic and clinical criteria, perioperative cerebral infarction were compared using Chi-square test. Results: 399 (43.4%) were classified as LOW and 522 (56.7%) patients as NORMAL. In the LOW group, there were more patients with diabetes, less patients with ICA severe stenosis and opening of anterior/posterior communicating artery. Occurrence of CHS per ultrasonographic criteria was higher in the LOW group (21.3% vs. 15.7%, P=0.03), but similar for clinical CHS criteria group (3.2%, vs 2.1%, p=0.28) and for frequency of perioperative cerebral infarction (5.8% vs.5.0%, p=0.60). Conclusion: Although patients with decreased flow velocities post-GA were more likely to meet ultrasonographic criteria for CHS, there were no differences in clinical CHS criteria. Our results suggest decreased flow velocities post-GA may not associated with incidence of CHS.