氯胺酮对腹部手术患者七氟醚MAC_(BAR)的影响

目的 评价氯胺酮对七氟醚抑制50%腹部手术患者切皮时应激反应的最低肺泡有效浓度(MAC_(BAR))的影响.方法 择期腹部手术患者44例,ASA Ⅰ或Ⅱ级,年龄30～60岁,随机分为2组(n=22):对照组(K_0组)和氯胺酮组(K_1组).麻醉诱导:静脉注射异丙酚2 mg/kg、芬太尼3 μg/kg和顺阿曲库铵0.15 mg/kg,气管插管后行机械通气.K_0组吸入七氟醚,K_1组吸入七氟醚的同时静脉输注氯胺酮14 μg·kg~(-1)·min~(-1).初始七氟醚呼气末浓度为3.0%.采用改良的序贯法进行试验,切皮时患者的心率或平均动脉压升高幅度≥基础值的15%定义为阳性反应,记录平衡点后各个由阳性反应到阴性反应的中点的浓度,取其平均值,即为MAC_(BAR),并计算其95%可信区间.结果 K_0组七氟醚MAC_(BAR)为3.25%(95%可信区间为3.05%～3.45%);K_1组七氟醚MAC_(BAR)为2.20%(95%可信区间为1.96%～2.44%),K_1组七氟醚MAC_(BAR)低于K_0组(P<0.05).结论 静脉输注氯胺酮14 μg~(-1)·min~(-1)可降低腹部手术患者七氟醚MAC_(BAR),增强七氟醚抑制应激反应的效应.

Effects of ketamine on MAC_(BAR) of sevoflurane in patients undergoing abdominal surgery

Objective To evaluate the effects of ketamine on the minimum alveolar concentration of scvoflurane for blunting adrenergic responses to skin incision (MAC_(BAR)) in patients undergoing abdominal surgery. Methods Forty-four ASA Ⅰ or Ⅱ patients aged 30-60 yr undergoing elective abdominal surgery were randomly divided into 2 groups (n=22 each) : control group (group K_0) and ketamine group (group K_1). Anesthesia was induced with propofol 2 mg/kg and fentanyl 3 μg/kg. Tracheal intubation was facilitated with cisatracurium 0.15 mg/kg. The patients were mechanically ventilated. Anesthesia was maintained with sevoflurane inhalation (the initial end-tidal concentration 3% ). Ketamine at 14 μg·kg~(-1)·min~(-1) was infused at the same time in group K,. The patients' response to skin incision was described as positive if MAP or HR increased by≥15%. If the response was positive, the end-tidal concentration of sevoflurane for the next patient was increased by 0.5%, while if negative, decreased by 0.5% . Results The MAC_(BAR) of scvoflurane was 3.25 % (95 % confidence interval 3.05%-3.45%) in group K_0, and 2.20% (95% confidence interval 1.96%-2.44%) in group K~1. The MAC_(BAR) of sevoflurane was significantly lower in group K~1 than in group K_0 (P<0.05). Conclusion Ketamine infusion at 14 μg·kg~(-1)·min~(-1) can reduce MAC_(BAR) of sevoflurane and enhance the inhibitory effect of sevoflurane on the stress response.