小剂量氯胺酮对妇科下腹部手术患者七氟醚肺泡气最低有效浓度的影响

Effects of low-dose ketamine on minimum alveolar concentration of sevoflurane in patients undegoing gynecological abdominal surgery

目的 探讨小剂量氯胺酮对妇科下腹部手术患者七氟醚肺泡气最低有效浓度（MAC）的影响.方法 择期拟行妇科下腹部手术患者51例,年龄36～49岁,体重指数≤30 kg/m2,ASA分级Ⅰ或Ⅱ级,采用随机数字表法,将患者随机分为对照组（C组,n=29）和氯胺酮组（K组,n=22）.K组静脉注射氯胺酮负荷量0.2 mg/kg,随后以14μg·kg-1·min-1维持,C组静脉输注等容量生理盐水,两组均吸入8%七氟醚进行麻醉诱导.麻醉维持：气管插管后,调节七氟醚蒸发罐,使呼气末七氟醚浓度达到预定值并至少稳定15 min后开始切皮.采用序贯法进行试验,初始浓度设为1.8%,发生体动反应,则下一例患者浓度增加0.2%,未发生体动反应,则下一例患者浓度降低0.2%.发生体动反应的标准：切皮时和切皮后60 s内患者躯干、四肢及头颈有可见的肌束收缩.计算七氟醚MAC及其95%可信区间.结果 K组七氟醚MAC为1.51%（95%可信区间为1.45%～1.58%）,C组七氟醚MAC为2.49%（95%可信区间为2.40%～2.57%）,两组比较差异有统计学意义（P〈0.05）.结论 静脉输注小剂量氯胺酮可增强七氟醚的麻醉效应.

Objective To investigate the effects of the low-dose ketamine on the minimum alveolar concentration （MAC） of sevoflurane in patients undergoing gynecological abdominal surgery.Methods Fifty-one ASA Ⅰ or Ⅱ patients aged 36-49 yr with body mass index ≤ 30 kg/m2 scheduled for gynecological abdominal surgery were randomly divided into control group （group C, n = 29） and ketamine group （group K, n = 22） . The paitents were unpremedicated. In group K, a loading dose of ketamine 0.2 mg/kg was injected intravenously followed by infusion at a rate of 14 μg·kg-1 ·min-1 , while equal volume of normal saline was given in group C. Anesthesia was induced with inhalation of sevoflurane （end-tidal concentration 4%-5%, maintaining for 5 min） in both groups. Endotracheal intubation was performed. The patients breathed sevoflurane until the predetermined target end-tidal sevoflurane concentration was reached for at least 15 min before skin incision. Occurrence of body movement was determined by any visible contraction of the muscle bundle of trunk, limbs, head and neck during skin incision and/or within 60 s after skin incision. The initial end-tidal concentration of sevoflurane was set at 1.8 % .If body movement occurred, the end-tidal concentration of sevoflurane was increased by 0.2% , while if not, decreased by 0.2% . MACs of sevoflurane were calculated. Results The MAC of sevoflurane was 1.51% （95% confidence interval 1.45%-1.58%） in group K, and 2.49% （95% confidence interval 2.40%-2.57%） in group C, and there was significant difference between the two groups （ P 〈 0.05） . Conclusion Intravenous infusion of the low-dose ketamine can enhance the anesthetic effect of sevoflurane in patients undergoing gynecological abdominal surgery.