吸入七氟烷对闭环系统控制的丙泊酚经静脉麻醉效果影响的研究

The effect of sevoflurane on the efficiency of a closed-loop control system for propofol anesthesia

目的 ：探讨吸入麻醉对闭环系统控制的经静脉麻醉效果的影响。方法 ：17例择期上腹部开腹手术患者接受CONCERT-CL闭环系统控制的丙泊酚经静脉麻醉。术中平稳阶段,Drager Zeus麻醉机自动完成预设的呼气末七氟醚浓度。观察七氟烷在达0.0、0.4、0.7和1.0个最低肺泡有效浓度（minimum alveolar concentration,MAC）后平衡5 min时的脑电双频谱指数（bispectral index,BIS）值以及丙泊酚的血浆和效应室浓度,同时记录血压和心率。结果 ：丙泊酚血浆和效应室浓度随七氟烷浓度升高而明显下降（P均〈0.01）。闭环系统控制设计的丙泊酚最低靶浓度为1.0μg/ml。当七氟烷达1.0个MAC时,有12例患者（70.6%）的丙泊酚效应室浓度降至1.0μg/ml,超出了闭环系统自动控制的范围,故予排除。而当七氟烷达0.4或0.7个MAC时,BIS值能够维持在40~60的预定范围内,仅有1例患者的BIS值〈40（38.86）。结论 ：在用闭环系统控制麻醉时,采用经静脉和吸入联合麻醉可在闭环系统的设计范围内通过调控经静脉用麻醉药的给药浓度而使BIS值维持在40~60的适宜范围内。

Objective： To investigate the effect of inhalational anesthesia on the efficiency of a closed-loop control system for intravenous anesthesia. Methods： A CONCERT-CL closed-loop control system for propofol anesthesia was applied in 17 patients with elective upper abdominal laparotomy. During stationary phase, sevoflurane was automatically delivered by Drager Zeus anesthesia machine. After equilibrium of sevoflurane [0.0, 0.4, 0.7, 1.0 minimum alveolar concentration（MAC）] for 5 min, the plasma and effect-site concentrations of propofol and bispectral index（BIS） were monitored and meanwhile the blood pressure and heart rate were recorded. Results： The plasma and effect-site concentrations of propofol decreased significantly when sevoflurane increased（P〈0.01）. Due to the design of the closed-loop control system, a minimum target concentration of propofol is 1.0 mg/ml. When sevoflurane reached at 1.0 MAC, the effect-site concentration of propofol decreased to 1.0 mg/ml in 12 cases（70.6%）, beyond the scope of the closed-loop control system. When sevoflurane reached at 0.4 or 0.7 MAC, BIS values were remained within a predetermined range of 40~60 with only one case less than 40（38.86）. Conclusion： In the closed-loop anesthesia systems, when combination of intravenous and inhaled anesthesia was used, BIS can be maintained in a predetermined range of 40~60 by automatic adjustment of the concentration of propofol. This study can provide some references data for the feasible and safe use of sevoflurane in the closed-loop control system for propofol anesthesia.