静吸复合麻醉下右美托咪定对老年患者颈椎手术运动诱发电位监测及术后躁动的影响

Effects of dexmedetomidine during combined intravenous-inhalational anesthesia on motor evoked potentials monitoring and postoperative agitation in elderly patients undergoing cervical spine surgery

目的 探讨静吸复合麻醉下不同剂量右美托咪定对老年患者颈椎手术运动诱发电位(MEPs)监测及术后躁动的影响.方法 择期全麻下行颈椎手术患者60例,性别不限,年龄65~81岁,体重51~78 kg,ASA分级Ⅰ或Ⅱ级,采用随机数字表法分为3组(n=20):对照组(C组)、低剂量右美托咪定组(D1组)和高剂量右美托咪定组(D2组).静脉注射咪达唑仑0.04 mg∕kg、顺式阿曲库铵0.15 mg∕kg、丙泊酚2 mg∕kg和舒芬太尼0.3~0.4μg∕kg诱导麻醉.麻醉诱导后采用神经电生理监测仪监测MEPs.吸入七氟醚呼气末浓度1%,靶控输注丙泊酚血浆靶浓度2~3μg∕ml维持麻醉,维持NTI值D2~E1.待T4∕T1>75% 时(T0)D1组经10 min静脉输注右美托咪定负荷剂量0.6μg∕kg,随后以0.3μg·kg^-1·h^-1的速率静脉输注至术毕;D2组经10 min静脉输注右美托咪定负荷剂量1μg∕kg,随后以0.3μg·kg^-1·h^-1的速率静脉输注至术毕;C组静脉输注等容量生理盐水.分别于T0、右美托咪定负荷剂量给药结束即刻(T1)和右美托咪定维持输注60 min(T2)记录MEPs有效引出情况、波幅和潜伏期.记录术中心血管事件和PACU期间躁动的发生情况.结果 与C组比较,D1组各时点MEPs的波幅、潜伏期和有效引出率差异无统计学意义(P>0.05),D2组T2时MEPs波幅降低,潜伏期延长,有效引出率降低,D1组和D2组术中心动过缓发生率升高,术后躁动发生率降低(P<0.05);与D1组比较,D2组T2时MEPs波幅降低,潜伏期延长,有效引出率降低(P<0.05),术中心动过缓和术后躁动发生率差异无统计学意义(P>0.05).结论 静吸复合麻醉下,术中经10 min静脉输注右美托咪定负荷剂量0.6μg∕kg,随后以0.3μg·kg^-1·h^-1的速率静脉输注对老年患者颈椎手术MEPs监测无影响,同时可以降低术后躁动的发生率.

Objective To investigate the effects of different doses of dexmedetomidine during com-bined intravenous-inhalational anesthesia on motor evoked potentials ( MEPs) monitoring and postoperative agitation in elderly patients undergoing cervical spine surgery. Methods Sixty patients of both sexes, aged 65-81 yr, weighing 51-78 kg, of American Society of Anesthesiologists physical statusⅠorⅡ, undergo-ing elective cervical spine surgery under general anesthesia, were divided into 3 groups ( n=20 each) using a random number table method: control group ( group C) , low-dose dexmedetomidine group ( group D1 ) and high-dose dexmedetomidine group ( group D2 ) . Anesthesia was induced by intravenous injection of mid-azolam 0. 04 mg∕kg, cisatracurium 0. 15 mg∕kg, propofol 2 mg∕kg and sufentanil 0. 3-0. 4 μg∕kg. MEPs was assessed with nerve electrophysiology monitor after induction of anesthesia. Anesthesia was maintained by inhalation of sevoflurane ( end-tidal concentration 1%) and target-controlled infusion of propofol ( target plasma concentration 2-3 μg∕ml). Narcotrend index was maintained at D2-E1. When T4∕T1>75% (at T0 ) , dexmedetomidine was intravenously infused over 10 min in a loading dose of 0. 6μg∕kg, followed by an infusion of 0. 3μg·kg^-1 ·h^-1 until the end of surgery in group D1 . Dexmedetomidine was intravenously infused over 10 min in a loading dose of 1 μg∕kg, followed by an infusion of 0. 3 μg·kg^-1 ·h^-1 until the end of surgery in group D2 . The equal volume of normal saline was given intravenously in group C. At T0 , immediately after the end of administration of dexmedetomidine loading dose ( T1 ) and at 60 min of dexme-detomidine infusion ( T2 ) , the effective elicitation of MEPs and amplitude and latency of MEPs were recor-ded. The intraoperative cardiovascular events and occurrence of postoperative agitation in postanesthesia care unit were recorded. Results Compared with group C, no significant change was found in the latency, amplitude and effective elicitation rate of MEPs at each time point in group D1 ( P>0. 05) , the amplitude of MEPs was significanty decreased, the latency of MEPs was prolonged, and the elicitation rate of MEPs was decreased at T2 in group D2 , and the incidence of bradycardia during operation was significanty in-creased, and the incidence of postoperative agitation was decreased in D1 and D2 groups ( P<0. 05) . Com-pared with group D1 , the amplitude of MEPs was significantly decreased, the latency of MEPs was pro-longed, and the effective elicitation rate of MEPs was decreased at T2 ( P<0. 05), and no significant change was found in the incidence of intraoperative bradycardia and postoperative agitation in group D2 ( P>0. 05) . Conclusion Dexmedetomidine infused over 10 min in a loading dose of 0. 6 μg∕kg, followed by an intravenous infusion of 0. 3 μg·kg^-1 ·h^-1 until the end of surgery during combined intravenous-inhala-tional anesthesia exerts no effect on MEPs monitoring, and can decrease the incidence of postoperative agita-tion at the same time in elderly patients undergoing cervical spine surgery.