To observe the effect of oxycodone for inhibition of myoclonus induced by etomidate during the induction of general anesthesia in middle-aged or elderly patients.

Sixty-two cases of patients undergoing elective general anesthesia, ASA Ⅰor Ⅱ grade, were assigned into middle aged group (45 to 54 years old) 30 cases, and aged group (65 to 74 years old) 32 cases. Induction of anesthesia: with oxygen mask(8 L/min) for five minutes, all patients were injected oxycodone intravenously in thirty seconds with modified sequential method. Two minutes later, all were injected etomidate 0.3 mg/kg intravenously in thirty seconds. Then, we assessed the occurrence and degree of myoclonus for two minutes continuously. After that, we administrated cisatracurium 2 mg/kg and fentanyl 3 μg/kg. We completed the mechanical ventilation with tracheal intubation in five minutes. Anesthesia was maintained with propofol (3.0 mg/L) and remifentanil(2.5~3.0 μg/L) in target controlled infusion(TCI) mode until the end of surgery. ED₅0 and 95%CI of oxycodone during the induction of general anesthesia were calculated. The total time of operation, extubation time and adverse effects such as nausea and vomiting were also recorded.

ED₅₀ of the middle-aged group and elderly group was 0.077 mg/kg and 0.062 mg/kg, and 95%CI of the two groups was 0.045-0.122 mg/kg and 0.043~0.101 mg/kg respectively. The dose of oxycodone used in middle-aged group was significantly higher than that in elderly patients group(P<0.05). There was no significant difference of adverse reaction between the two groups(P>0.05).

The ED₅₀ and 95%CI of oxycodone for inhibition of myoclonus induced by etomidate during the induction of general anesthesia in middle-aged or elderly patients are 0.077 mg/kg and 0.062 mg/kg, 0.045-0.122 mg/kg and 0.043-0.101 mg/kg respectively.

Oxycodone; Etomidate; Myoclonus; Elderly