: 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 for association = 9.9, P < 0.05; chi 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.
In a retrospective review of a large series of carotid operations, regional anesthesia was shown to be applicable to the vast majority of patients with good clinical outcome. Although the advantages over general anesthesia are perhaps small, the versatility and safety of the technique is sufficient reason for vascular surgeons to include it in their armamentarium of surgical skills. Considering that carotid endarterectomy is a procedure in which complication rates are exceedingly low, a rigidly controlled, prospective randomized trial may be required to accurately assess these differences.
BACKGROUND In previous studies, we found that approximately 25% of patients having carotid endarterectomy with general anesthesia (CEA general) develop cognitive dysfunction compared with a surgical control Group 1 day and 1 mo after surgery. In this study, we tested the hypothesis that patients having CEA with regional anesthesia (CEA regional) will develop significant cognitive dysfunction 1 day after surgery compared with a control group of patients receiving sedation 1 day after surgery. We did not study persistence of dysfunction. METHODS To test this hypothesis, we enrolled 60 patients in a prospective study. CEA regional was performed with superficial and deep cervical plexus blocks in 41 patients. The control group consisted of 19 patients having coronary angiography or coronary artery stenting performed with sedation. A control group is necessary to account for the “practice effect” associated with repeated cognitive testing. The patients from the CEA regional group were enrolled at New York Medical Center and the control group at Columbia-Presbyterian Medical Center. The cognitive performance of all patients was evaluated using a previously validated battery of neuropsychometric tests. Differences in performance, 1 day after compared with before surgery, were evaluated by both event-rate and group-rate analyses. RESULTS On postoperative day 1, 24.4% of patients undergoing CEA regional had significant cognitive dysfunction, where “significant” was defined as a total deficit score ≥2 SD worse than the mean performance in the control group. CONCLUSIONS Patients undergoing CEA regional had an incidence of cognitive dysfunction which was not different than patients having CEA general as previously published and compared with a contemporaneously enrolled group.
Systemic administration of dexmedetomidine (DEX) decreases cerebral bloodflow (CBF) via direct alpha-2-mediated constriction of cerebral blood vessels and indirectly via its effect on the intrinsic neural pathway modulating vascular smooth muscle. Reduction in CBF without a concomitant decrease in cerebral metabolic rate has raised concerns that DEX may limit adequate cerebral oxygenation of brain tissue in patients with already compromised cerebral circulation (e.g., carotid endarterectomy [CEA]). In this study, we established the incidence of intraarterial shunting used as a sign of inadequate oxygen delivery in a consecutive series of 123 awake CEA performed in our institution using DEX as a primary sedative. Data were prospectively recorded in 151 patients who underwent CEA during the study period. Eighteen patients were sedated with midazolam and fentanyl (M/F) for medical or logistical reasons. Patients thought to be at risk of an intraoperative stroke were treated with a prophylactic intraarterial shunt. These patients, as well as those who required general anesthesia, were excluded from the final analysis. Five patients (4.3%) in the DEX group required intraarterial shunts. The incidence of shunting in patient undergoing awake CEA in our institution is 10% (historical control). No patients developed a stroke or other serious complications. It appears that the use of DEX as a primary sedative drug for CEA does not increase the incidence of intraarterial shunts.
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