氯胺酮对腹部手术患者七氟醚MACBAR的影响

Effects of ketamine on MACBAR of sevoflurane in patients undergoing abdominal surgery

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（MACBAR）的影响。方法择期腹部手术患者44例，ASAⅠ或Ⅱ级，年龄30-60岁，随机分为2组（n=22）：对照组（K0组）和氯胺酮组（K1组）。麻醉诱导：静脉注射异丙酚2mg／kg、芬太尼3μg／kg和顺阿曲库铵0．15mg／kg，气管插管后行机械通气。K组吸入七氟醚，K1组吸入七氟醚的同时静脉输注氯胺酮14μg·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MACBAR并计算其95％可信区间。结果K0组七氟醚MACBAR为3．25％（95％可信区间为3．05％～3．45％）；K1组七氟醚MACBAR为2．20％（95％可信区间为1．96％～2．44％），K1组七氟醚MAC。低于K0组（P〈0．05）。结论静脉输注氯胺酮14μg·kg^-1·min^-1可降低腹部手术患者七氟醚MACBAR,增强七氟醚抑制应激反应的效应。

Objective To evaluate the effects of ketamine on the minimum alveolar concentration of sevoflurane for blunting adrenergic responses to skin incision （MACBAR） 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 K0 ） and ketamine group （group K1 ）. 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 K1 . 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 MACBAR of sevoflurane was 3.25 % （95 % confidence interval 3.05%-3.45%） in group Ko, and 2.20% （95% confidence interval 1.96%-2.44%） in group Ki. The MACBAR. of sevofiurane was significantly lower in group K, than in group K0 （ P 〈 0. 05）. Conclusion Ketamine infusion at 14μg· kg^-1· min^-1 can reduce MACBAR of sevoflurane and enhance the inhibitory effect of sevoflurane on the stress response.