Sebel P S, Erwin C W, Neville W K
Anaesthetic Unit, London Hospital Medical College, Whitechapel.
Br J Anaesth. 1987 Dec;59(12):1492-6. doi: 10.1093/bja/59.12.1492.
Somatosensory potentials evoked in response to median nerve stimulation were studied in 10 patients during surgery under general anaesthesia with halothane (five patients) or enflurane (five patients). Bipolar scalp responses (near field) and scalp to non-cephalic reference (far field) potentials were recorded before the induction of anaesthesia, and after 15 min stabilization at each of 0.5, 1.0, 1.5 and 2.0% end-tidal concentrations of anaesthetic agent. Both agents produced similar effects. The latency of the bipolar responses was increased and the amplitude decreased. The amplitude of the far field, subcortically generated, potentials measured from the scalp to non-cephalic electrodes did not decrease as much as the near field potential with increasing concentrations of volatile anaesthetic, although the latency of the potential recorded at the frontal electrode increased. At higher anaesthetic concentrations the virtual elimination of the near field potential caused the frontal and rolandic potentials to appear to be identical. Since far field somatosensory evoked potentials are preserved during deep anaesthesia, they should be considered for use when measurement of evoked responses is required for monitoring purposes.
在全身麻醉下使用氟烷（5例患者）或恩氟烷（5例患者）进行手术期间，对10例患者进行了正中神经刺激诱发的体感诱发电位研究。在麻醉诱导前以及在麻醉剂呼气末浓度分别为0.5%、1.0%、1.5%和2.0%稳定15分钟后，记录双极头皮反应（近场）和头皮至非头部参考电极的电位（远场）。两种药物产生的效果相似。双极反应的潜伏期延长，波幅降低。从头皮到非头部电极测量的皮质下产生的远场电位波幅，随着挥发性麻醉剂浓度的增加，其降低程度不如近场电位明显，尽管额叶电极记录的电位潜伏期延长。在较高的麻醉浓度下，近场电位几乎消失，导致额叶和中央沟电位看起来相同。由于在深度麻醉期间远场体感诱发电位得以保留，因此在监测需要测量诱发电反应时，应考虑使用远场体感诱发电位。
