Effect of dexmedetomidine on quality of intraoperative wake-up test in patients undergoing balloon occlusion test of the internal carotid artery

Objective To evaluate the effect of dexmedetomidine on the quality of intraoperative wake-up test in the patients undergoing balloon occlusion test of the internal carotid artery. Methods Forty-two patients of either sex with intracranial aneurysm, aged 57-78 yr, weighing 53-86 kg, of American Society of Anesthesiologists physical status Ⅱ or Ⅲ, scheduled for elective balloon occlusion test of the internal carotid artery under general anesthesia, were assigned into 2 groups(n=21 each)using a random number table: propofol combined with remifentanil group(group PR)and dexmedetomidine combined with propofol and remifentanil group(group DPR). In group DPR, dexmedetomidine was intravenously infused over 15 min in a loading dose of 0.5μg·kg-1 before induction of anesthesia, followed by an infusion of 0.3 μg·kg-1·h-1 throughout surgery.Propofol and remifentanil were given by target-controlled infusion(TCI)after infusion of the loading dose.The patients were mechanically ventilated after placement of the laryngeal mask airway.Maintenance of anesthesia was as follows: propofol and remifentanil were given by TCI with the target plasma concentrations of 0.5-1.0 μg/ml and 1-3 ng/ml, respectively, in group DPR; propofol and remifentanil were given by TCI with the target plasma concentrations of 3-5 μg/ml and 3-6 ng/ml, respectively, in group PR.Bispectral index(BIS)value was maintained at 40-60.Before wake-up test, propofol infusion was stopped and the target plasma concentration of remifentanil was decreased to 0.5 ng/ml in two groups, and the infusion rate of dexmedetomidine was decreased to 0.1 μg·kg-1·h-1 in group DPR.The wake-up time was recorded and the wake-up quality was assessed.After admission to the operating room(T0, baseline), at 10 min before wake-up test(T1), immediately after patients were wakened(T2), at 10 min after patients were wakened(T3)and at the end of wake-up test(T4), the mean blood pressure(MAP), heart rate, respiratory rate(RR), SpO2 and BIS values were recorded.The development of intraoperative awareness, emergence time, postoperative agitation, nausea and vomiting, regurgitation and aspiration and severe pain was recorded. Results MAP, heart rate, SpO2 and RR were all within the normal range during wake-up period in two groups.Compared with the baseline at T0, MAP was significantly decreased at T1, 3, 4 in group PR, and BIS value was decreased at T1-4 in DPR and PR groups(P 0.05). No cardiovascular events, respiratory depression, intraoperative awareness, postoperative nausea and vomiting, regurgitation and aspiration or severe pain was found in two groups. Conclusion Dexmedetomidine can raise the quality of intraoperative wake-up test in the patients undergoing balloon occlusion test of the internal carotid artery. Key words: Dexmedetomidine; Monitoring, intraoperative; Carotid artery, internal; Embolization, therapeutic; Wake-up test