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

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