高频（30-200 Hz）丘脑皮层脑电节律减弱与麻醉作用相关：来自右美托咪定的证据
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Attenuation of high-frequency (30-200 Hz) thalamocortical EEG rhythms as correlate of anaesthetic action: evidence from dexmedetomidine.
背景
γ（30-80 赫兹）和高频γ（80-200 Hz）丘脑皮层脑电节律参与意识过程并可被异氟烷和异丙酚减弱。为探讨这种衰减与麻醉作用相关的假说，我们在这个节律揭示右旋美托咪啶（选择性肾上腺素能α2激动剂，具有较小的催眠效力的作用。
方 法
我们记录了桶状皮层和丘脑腹后内侧核的局部场电位。测量10只载有装置的大鼠测量光谱功率，30-50 Hz，51-75 Hz，76-125 Hz，126-200 Hz频段。基础值、右美托咪定4种血浆浓度采用静脉靶控输注（1.86, 3.75, 5.63 和 7.50 ng ml -1）、恢复期。同样在0.3-200 Hz测量丘脑连贯性。
结 果
5.63 ng ml -1时正向反射丧失（LORR）。右美托咪定在所有频段均引起皮质（P＜0.04）和丘脑（P ≤ 0.0051）对数功率线性的浓度依赖性的衰减。皮质和丘脑的斜率相似。在76-200 赫兹下，右美托咪定丘脑脑电电位斜率不到其他药物的一半（P <0.003）。LORR与δ频段（0.3-4.0 Hz）丘脑连贯性的增加相关（P＜0.001）。异丙酚和异氟醚也增加了低频相干性。
结 论
右美托咪定可使高频丘脑的节律衰减，但较异氟醚和异丙酚的程度轻。右美托咪定和其他麻醉药物对丘脑节律的主要差异，进一步支持丘脑功能受损和麻醉之间的联系。δ相干性的增加可能反映了丘脑皮层网络循环超极化并可能是意识消失的标志。
原始文献摘要
Cornelissen L, Donado C, Lee JM, et al. Clinical signs and electroencephalographic patterns of emergence from sevoflurane anaesthesia in children: An observational study[J]. European journal of anaesthesiology, 2017.
BACKGROUND Few studies have systematically described relationships between clinical–behavioural signs, electroencephalographic (EEG) patterns and age during emergence from anaesthesia in young children.
OBJECTIVE To identify the relationships between end-tidal sevoflurane (ETsevoflurane) concentration, age and frontal EEG spectral properties in predicting recovery of clinical–behavioural signs during emergence from sevoflurane in children 0 to 3 years of age, with and without exposure to nitrous oxide. The hypothesis was that clinical signs occur sequentially during emergence, and that for infants aged more than 3 months, changes in alpha EEG power are
correlated with clinical–behavioural signs.
DESIGN An observational study.
SETTING A tertiary paediatric teaching hospital from December 2012 to August 2016.
PATIENTS Ninety-five children aged 0 to 3 years who required surgery below the neck.
OUTCOME MEASURES Time–course of, and ET sevoflurane concentrations at first gross body movement, first cough, first grimace, dysconjugate eye gaze, frontal (F7/F8) alpha EEG power (8 to 12 Hz), frontal beta EEG power (13 to 30 Hz), surgery-end.
RESULTS Clinical signs of emergence followed an orderly sequence of events across all ages. Clinical signs occurred over a narrow ET sevoflurane, independent of age [movement: 0.4% (95% confidence interval (CI), 0.3 to 0.4), cough 0.3% (95% CI, 0.3 to 0.4), grimace 0.2% (95% CI, 0 to 0.3); P > 0.5 for age vs. ET sevoflurane]. Dysconjugate eye gaze was observed between ET sevoflurane 1 to 0%. In children more than 3 months old, frontal alpha EEG oscillations were
present at ET sevoflurane 2.0% and disappeared at 0.5%. Movement occurred within 5 min of alpha oscillation disappearance in 99% of patients. Nitrous oxide had no effect on the time course or ET sevoflurane at which children showed body movement, grimace or cough.
CONCLUSION Several clinical signs occur sequentially during emergence, and are independent of exposure to nitrous oxide. Eye position is poorly correlated with other clinical signs or ET sevoflurane. EEG spectral characteristics may aid prediction of clinical–behavioural signs in children more than 3 months.
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