Abstract: Objective To evaluate the effects of different doses of dexmedetomidine on the median effective concentration of sufentanil in inhabiting cardiovascular response to tracheal intubation with the probability of 50%（EC50） in the elderly patients. Methods Ninety-six elderly patients who were undergoing elective abdominal operation under general anesthesia,with ASA physical statusⅠ-Ⅱ, were randomly divided into four groups：the control group（Group C） which were injected saline 10 ml before anesthesia induction;the dexmedetomidine group （Group D1, Group D2 and Group D3, 0.1, 0.3 and 0.5 μg/kg of dexmedetomidine were respectively injected before anesthesia induction for 5-15 min）. All the patients were received propofol with a target concentration of 2.5 μg/ml and total intravenous anesthesia of sufentanil with a target concentration of preset dose through target-controlled infusion pump. Dixon′s up-and-down method was used to determine the dose of sufentanil. The number of patients with sinus bradycardia, hypotension and cough before intubation was recorded, as well as the number of patients with agitation and pain in the PACU and the Ramsay sedation score at 2 hours after surgery. Results The EC50 of sufentanil in inhibiting the hemodynamic response to tracheal intubation in the elderly patients with different doses of dexmedetomidine administered intravenously before general anesthesia induction with the target concentration of propofol at 2.5 μg/mL were 0.246 ng/mL in group C, 0.238 ng/mL in group D1, 0.215 ng/mL in group D2, and 0.199 ng/mL in group D3, respectively. Compared with group C, the incidence of bradycardia before tracheal intubation was higher in group D3, and the incidence of agitation during extubation was lower in groups D2 and D3（P<0.05）. There were no significant differences in the incidence of hypotension and cough before tracheal intubation, as well as the incidence of pain in the PACU, and the Ramsay sedation score at 2 hours after surgery（P>0.05）. Conclusion As the dose of dexmedetomidine increased, the target concentration of sufentanil required for tracheal intubation in elderly patients decreased, and 0.3 and 0.5 μg/kg dexmedetomidine before induction of general anesthesia reduced agitation in the PACU in elderly patients.

Key words: dexmedetomidine, sufentanil, tracheal intubation, dose-response relationship, elderly

摘要： 目的 观察复合不同剂量右美托咪定时对舒芬太尼抑制老年患者气管插管的半数有效剂量（ED50）的影响。方法 选择全身麻醉下行腹部手术的老年患者96例,ASA分级Ⅰ~Ⅱ级,将患者分为4组：对照组（C组,麻醉诱导前输注10 mL生理盐水）和右美托咪定组（D1、D2、D3组,分别于麻醉诱导前静脉泵注右美托咪啶0.1、0.3、0.5 μg/kg,泵注时间5~15 min）。所有患者均采用丙泊酚靶控浓度2.5 μg/mL及预设靶浓度的舒芬太尼全凭静脉麻醉。气管插管时采用序贯法测定舒芬太尼目标靶控浓度,记录所有患者插管前出现窦性心动过缓、低血压、呛咳的例数,并记录在PACU期间躁动、疼痛例数及术后2小时的镇静评分。结果 全麻诱导前静脉给予不同剂量右美托咪定且丙泊酚效应室浓度2.5 μg/mL下舒芬太尼抑制老年人气管插管心血管反应的EC50分别是：C组：0.246 ng/mL,D1组0.238 ng/mL,D2组0.215 ng/mL,D3组0.199 ng/mL。与C组相比,D3组气管插管前出现心动过缓的发生率较高,D2、D3组拔管期间患者躁动发生率较低,差异有统计学意义（P<0.05）。各组患者气管插管前出现低血压、呛咳的发生率及拔管期间疼痛的发生率以及术后2小时Ramsay评分差异均无统计学意义（P>0.05）。结论 随着右美托咪定的剂量增加,老年患者气管插管所需的舒芬太尼目标靶控浓度呈剂量依赖性下降,且全身麻醉诱导前静脉滴注0.3 μg/kg和0.5 μg/kg右美托咪定能够降低老年患者PACU期间的躁动发生情况。

关键词: 右美托咪定, 舒芬太尼, 气管插管, 剂量效应关系, 老年患者