Bischoff P, Schneider G, Kochs E
Klinik und Poliklinik für Anästhesiologie, Universitätsklinikum Hamburg-Eppendorf, Gebäude O50, Martinistrasse 52, 20246, Hamburg, Germany.
Handb Exp Pharmacol. 2008(182):379-408. doi: 10.1007/978-3-540-74806-9_18.
Anesthesia cannot be defined in an unambiguous manner. The essential components of general anesthesia are absence of consciousness and pain. This translates into two particular qualities: (1) sedation and hypnosis, i.e., mental blockade and (2) analgesia/antinociception, i.e., sensory blockade. Anesthetic actions on these two subcomponents are difficult to separate. On the one hand, very few anesthetics act exclusively on one of these components. On the other hand, these components are closely related to each other. Unconsciousness prevents (conscious) perception of pain, and nociception may serve as an arousal stimulus and change the level of sedation and hypnosis. The art of anesthesia lies in adequate dosing of drugs to reach both mental and sensory blockade. Drug administration can be based on pharmacokinetic considerations. Pharmacokinetic models allow an estimation of what happens to the administered drug in the body. Models with an effect site compartment may facilitate a tailored administration of anesthetic drugs. Finally, the quantification of pharmacodynamic effects allows a precise titration of drugs. Clinical assessment of mental blockade is often dichotomous, and therefore not very helpful to guide drug administration. Several scoring systems exist, but once consciousness is lost they become less reliable, in particular because reaction to stimuli is assessed, which mixes assessment of mental blockade with assessment of sensory blockade. Clinical assessment of analgesia requires a conscious patient, so antinociception is difficult to measure. Several methods of objective quantification on the basis of electrical brain activity are discussed including EEG and evoked potentials. Despite numerous indexes of the hypnotic component of anesthesia, there is no parameter that unambiguously quantifies the level of mental or sensory blockade.
麻醉无法以一种明确无误的方式来定义。全身麻醉的基本要素是意识消失和疼痛消失。这转化为两个特定的特性：（1）镇静和催眠，即精神阻滞；（2）镇痛/抗伤害感受，即感觉阻滞。麻醉对这两个子成分的作用很难分开。一方面，很少有麻醉药仅作用于其中一个成分。另一方面，这些成分彼此密切相关。意识丧失可防止（有意识地）感知疼痛，而伤害感受可能作为一种唤醒刺激并改变镇静和催眠的程度。麻醉的艺术在于合理给药以达到精神和感觉阻滞。药物给药可基于药代动力学考虑。药代动力学模型可以估计给药药物在体内的变化情况。具有效应室的模型可能有助于量身定制麻醉药物的给药。最后，药效学效应的量化允许精确滴定药物。精神阻滞的临床评估通常是二分法的，因此对指导药物给药帮助不大。存在几种评分系统，但一旦意识丧失，它们就变得不太可靠，特别是因为对刺激的反应是被评估的，这将精神阻滞的评估与感觉阻滞的评估混在一起。镇痛的临床评估需要患者保持清醒，因此抗伤害感受很难测量。讨论了几种基于脑电活动的客观量化方法，包括脑电图和诱发电位。尽管有许多麻醉催眠成分的指标，但没有一个参数能明确量化精神或感觉阻滞的程度。
