Maksimow A, Särkelä M, Långsjö J W, Salmi E, Kaisti K K, Yli-Hankala A, Hinkka-Yli-Salomäki S, Scheinin H, Jääskeläinen S K
Turku PET Centre, University of Turku, P.O. Box 52, FIN-20521 Turku, Finland.
Clin Neurophysiol. 2006 Aug;117(8):1660-8. doi: 10.1016/j.clinph.2006.05.011. Epub 2006 Jun 27.
To study the effects of S-ketamine on the EEG and to investigate whether spectral entropy of the EEG can be used to assess the depth of hypnosis during S-ketamine anesthesia.
The effects of sub-anesthetic (159 (21); mean (SD) ng/ml) and anesthetic (1,959 (442) ng/ml) serum concentrations of S-ketamine on state entropy (SE), response entropy (RE) and classical EEG spectral power variables (recorded using the Entropy Module, GE Healthcare, Helsinki, Finland) were studied in 8 healthy males. These EEG data were compared with EEG recordings from 6 matching subjects anesthetized with propofol.
The entropy values decreased from the baseline SE 85 (3) and RE 96 (3) to SE 55 (18) and RE 72 (17) during S-ketamine anesthesia but both inter- and intra-individual variation of entropy indices was wide and their specificity to indicate unconsciousness was poor. Propofol induced more pronounced increase in delta power (P<0.02) than S-ketamine, whereas anesthetic S-ketamine induced more high frequency EEG activity in the gamma band (P<0.001). Relative power of 20-70 Hz EEG activity was associated with high SE (P=0.02) and RE (P=0.03) values during S-ketamine anesthesia.
These differences in low and high frequency EEG power bands probably explain why entropy monitor, while adequate for propofol, is not suitable for assessing the depth of S-ketamine anesthesia.
The entropy monitor is not adequate for monitoring S-ketamine-induced hypnosis.
研究S-氯胺酮对脑电图（EEG）的影响，并探讨EEG频谱熵能否用于评估S-氯胺酮麻醉期间的催眠深度。
在8名健康男性中研究了亚麻醉剂量（159（21）；均值（标准差）ng/ml）和麻醉剂量（1959（442）ng/ml）的S-氯胺酮血清浓度对状态熵（SE）、反应熵（RE）和经典EEG频谱功率变量（使用芬兰赫尔辛基通用电气医疗集团的熵模块记录）的影响。将这些EEG数据与6名接受丙泊酚麻醉的匹配受试者的EEG记录进行比较。
在S-氯胺酮麻醉期间，熵值从基线SE 85（3）和RE 96（3）降至SE 55（18）和RE 72（17），但熵指数的个体间和个体内变异都很大，其指示无意识状态的特异性较差。丙泊酚引起的δ波功率增加比S-氯胺酮更明显（P<0.02），而麻醉剂量的S-氯胺酮在γ波段引起更多的高频EEG活动（P<0.001）。在S-氯胺酮麻醉期间，20-70Hz EEG活动的相对功率与高SE（P=0.02）和RE（P=0.03）值相关。
低频和高频EEG功率带的这些差异可能解释了为什么熵监测仪虽然适用于丙泊酚，但不适用于评估S-氯胺酮麻醉的深度。
熵监测仪不适用于监测S-氯胺酮诱导的催眠。
