Voss L J, Ludbrook G, Grant C, Sleigh J W, Barnard J P M
Waikato Clinical School, University of Auckland, Hamilton, New Zealand.
Acta Anaesthesiol Scand. 2006 Mar;50(3):313-9. doi: 10.1111/j.1399-6576.2006.00914.x.
Different volatile anesthetic agents have differing propensities for inducing seizures. A measure of the predilection to develop seizures is the presence of interictal spike discharges (spikes) on the electrocorticogram (ECoG). In this study, we investigated the propensity of desflurane to induce cortical spikes and made a direct objective comparison with enflurane, isoflurane, and sevoflurane. The ECoG effects of desflurane have not been previously reported.
After establishment of invasive monitoring and a parasagittal array of eight electrodes to record the ECoG; eight adult merino sheep were given a series of short inhalational anesthetics (using desflurane, enflurane, sevoflurane and isoflurane); each titrated to ECoG burst suppression. Anesthetic effect was estimated by the effects on the approximate entropy of the ECoG. The effect of anesthetic on the spike-rate in the ECoG was analyzed using a non-linear mixed-effect method with a sigmoid Emax model.
A similar 'depth of anesthesia' was achieved for each agent, as estimated by the approximate entropy. The mean (SD) values of Emax for the spike-rate vs. approximate entropy relationship were desflurane 0.5 (0.9), enflurane 17.2 (4.0), isoflurane 0.7 (1.2), and sevoflurane 5.3 (1.2) spikes/min. The spike rate caused by desflurane was similar to isoflurane and significantly lower than that of enflurane (P < 0.001), and sevoflurane (P = 0.009).
Desflurane induces minimal cerebral cortical spike activity when administered to burst suppression, consistent with its low propensity for inducing seizures in non-epileptic brains. The agents can be ranked by their relative ability to cause spike activity: enflurane >> sevoflurane > isoflurane = desflurane.
不同的挥发性麻醉剂诱发癫痫的倾向不同。衡量发生癫痫倾向的一个指标是脑电图（ECoG）上发作间期棘波放电（棘波）的出现情况。在本研究中，我们调查了地氟烷诱发皮层棘波的倾向，并与恩氟烷、异氟烷和七氟烷进行了直接客观的比较。此前尚未报道地氟烷对脑电图的影响。
在建立有创监测并放置一个由八个电极组成的矢旁阵列以记录脑电图后，给八只成年美利奴羊使用一系列短效吸入麻醉剂（使用地氟烷、恩氟烷、七氟烷和异氟烷）；每种麻醉剂滴定至脑电图爆发抑制。通过对脑电图近似熵的影响来评估麻醉效果。使用具有S形Emax模型的非线性混合效应方法分析麻醉剂对脑电图棘波率的影响。
通过近似熵估计，每种麻醉剂达到了相似的“麻醉深度”。棘波率与近似熵关系的Emax平均值（标准差）分别为：地氟烷0.5（0.9）、恩氟烷17.2（4.0）、异氟烷0.7（1.2）和七氟烷5.3（1.2）次/分钟。地氟烷引起的棘波率与异氟烷相似，且显著低于恩氟烷（P < 0.001）和七氟烷（P = 0.009）。
地氟烷在滴定至爆发抑制时诱发的大脑皮层棘波活动最少，这与其在非癫痫性大脑中诱发癫痫的低倾向一致。这些麻醉剂可根据其引起棘波活动的相对能力进行排序：恩氟烷 >> 七氟烷 > 异氟烷 = 地氟烷。
