Dexmedetomidine for awake carotid endarterectomy: Efficacy, hemodynamic profile, and side effects

A randomized, double-masked, placebo-controlled study was designed to compare dexmedetomidine as a primary sedative agent with a commonly used drug combination in patients undergoing awake carotid endarterectomy (CEA). Sixty-six patients undergoing CEA (ASA II-IV) were randomly assigned to receive either dexmedetomidine (total dose of 97.5 +/- 54.7 mcg) or normal saline (control). Supplemental doses of midazolam, fentanyl, and/or propofol were administered as deemed necessary by the anesthesiologist. An observer blinded to the study drug assessed sedation level (Observer's Assessment of Alertness-Sedation [OAA/S] scale). The primary outcomes were defined as the number of patients with an OAA/S score of 4 intraoperatively and an OAA/S score of 5 postoperatively. The authors also compared cardiorespiratory parameters, intra- and postoperative side effects, and complications. Chi-square tests were used to analyze the primary endpoints. All secondary parameters were analyzed using the Wilcoxon rank sum test. Three patients in the dexmedetomidine group (10%) had an OAA/S score of 4 at all four time points assessed intraoperatively, while no patient in the control group had a score of 4 at all the time points considered. Thirteen patients in the dexmedetomidine group had a score of 4 at three or more time points (42%) compared with six patients (19%) in the control group. Four patients in the control group (13%) and one patient in the dexmedetomidine group (3%) did not achieve a score of 4 at any of the four critical intraoperative time points (chi(2) for association = 9.9, P < 0.05; chi(2) for a trend = 8.6, P < 0.004, with the trend favoring dexmedetomidine). More patients in the control group required treatment with metoprolol (26% vs. 6%, P = 0.04) and labetalol (48% vs/ 6%, P < 0.01). Plasma levels of norepinephrine were significantly lower in the dexmedetomidine group during and after surgery compared with the control group. Six patients (19%) in the dexmedetomidine group required intra-arterial shunts, while only two patients (6%) required shunts in the control group (P = 0.16). These data show that the use of dexmedetomidine in patients undergoing awake CEA resulted in fewer fluctuations from the desired sedation level. Patients receiving dexmedetomidine required less antihypertensive therapy compared with the midazolam/fentanyl/propofol combination. The effect of dexmedetomidine on cerebrovascular circulation in the study population needs further investigation.