七氟醚、异氟醚和地氟醚对神经外科手术患者经颅电刺激运动诱发电位的影响

Effects of sevoflurane, isoflurane and desflurane on transcranial electrical motor evoked potentials in patients undergoing neurosurgery

目的 比较七氟醚、异氟醚和地氟醚对神经外科手术患者经颅电刺激运动诱发电位（MEPs）的影响。方法择期行神经外科手术患者60例，年龄18～64岁，ASA分级Ⅰ或Ⅱ级。随机分为3组（n=20）：七氟醚组、异氟醚组和地氟醚组。监测BIS值和经颅电刺激MEPs。调节七氟醚、异氟醚和地氟醚吸入浓度，使其呼气末浓度分别达到0．50、0．75、1．00和1．30MAC，每一浓度均维持15min，视为稳态呼气末浓度。于给予吸入麻醉药前（基础状态）和达到各稳态呼气末浓度（T1-4）时，记录MEPs的波幅和潜伏期以及BIS值。记录MEPs波形记录失败情况。结果与七氟醚组和异氟醚组比较，地氟醚组T1-2时波幅和BIS值降低，T1-4。时潜伏期延长（P〈0．05）；七氟醚组和异氟醚组各指标比较差异无统计学意义（P〉0．05）。七氟醚组、异氟醚和地氟醚组基础状态、T1、T2时的记录失败率均为0；T1时记录失败率分别为0、5％和20％，三组比较差异无统计学意义（P〉0．05）；T4时记录失败率分别为5％、20％和45％，与七氟醚组和异氟醚组比较，地氟醚组记录失败率升高（P〈0．05）；七氟醚组和异氟醚组比较差异无统计学意义（P〉0．05）。结论地氟醚对神经外科手术患者经颅电刺激MEPs的抑制作用强于七氟醚和异氟醚。术中行MEPs监测时，七氟醚和异氟醚适宜的呼气末浓度为1．00MAC，地氟醚为0．75～1．00MAC。

Objective To compare the effects of sevoflurane, isoflurane and desflurane on transcranial electrical motor evoked potentials （MEPs） in patients undergoing neurosurgery. Methods Sixty ASA Ⅰ or Ⅱ patients aged 18-64 yr undergoing neurosurgery were randomly divided into 3 groups （ n = 20each） ： sevoflurane group, isoflurane group and desflurane group. BIS value and MEPs were monitored. The end-tidal concentrations of sevoflurane, isoflurane and desflurane were adjusted and maintained at 0.50, 0.75, 1.00 and 1.30 MAC respectively for at least 15 min during 6 stimuli delivered at 1000 Hz and 300 V lasting for 75 μs. The amplitudes and latency of MEPs and BIS value were recorded before administration （baseline） and the each stable state （T1-4） . The failure rate of MEPs was also recorded. Results The amplitude of MEPs and BIS value were significandy decreased at T1,2 and the latency of MEPs was prolonged at T1-4 in desflurane group compared with sevoflu- rane and isoflurane groups （ P 〈 0.05） . There was no significant difference in the amplitudes and latency of MEPs and BIS value between group sevoflurane and isoflurane （ P 〉 0.05）. The failure rates of MEPs were 0 at baseline, Tt and T2, 0, 5% and 20% at T3 , and 5% , 20% and 45% at T4 in sevoflurane, isoflurane and desflurane groups respectively. The failure rate of MEPs was significantly higher in desflurane group than in sevoflurane and isoflurane groups （ P 〈 0.05 ）. Conclusion Desflurane has greater suppressive effect on MEPs than sevoflurane and isoflurane. 1.00 MAC of sevoflurane and isoflurane, while 0.75-1.00 MAC of desflurane may be the suitable end-tidal concentration for MEP monitoring.