异氟烷可减弱山羊脑电图及丘脑网状结构对伤害性刺激的反应。

Isoflurane blunts electroencephalographic and thalamic-reticular formation responses to noxious stimulation in goats.

作者信息

Antognini J F, Carstens E

机构信息

Department of Anesthesiology, University of California, Davis 95616, USA.

出版信息

Anesthesiology. 1999 Dec;91(6):1770-9. doi: 10.1097/00000542-199912000-00031.

DOI:10.1097/00000542-199912000-00031

PMID:10598621

Abstract

BACKGROUND

Anesthetics, including isoflurane, depress the electroencephalogram (EEG). Little is known about the quantitative effects of isoflurane on EEG and subcortical electrical activity responses to noxious stimulation. The authors hypothesized that isoflurane would depress the results of EEG and subcortical response to noxious stimulation at concentrations less than those needed to suppress movement. Furthermore, determination of regional differences might aid in elucidation of sites of anesthetic action.

METHODS

Ten goats were anesthetized with isoflurane, and minimum alveolar concentration (MAC) was determined using a noxious mechanical stimulus. Depth electrodes were inserted into the midbrain reticular formation and thalamus. Needle electrodes placed in the skull periosteum measured bifrontal and bihemispheric EEG. The noxious stimulus was applied at each of four anesthetic concentrations: 0.6, 0.9, 1.1, and 1.4 MAC.

RESULTS

At an isoflurane concentration of 0.6 MAC, the noxious stimulus activated the midbrain reticular formation, thalamic, and bifrontal-hemispheric regions, as shown by decreased high-amplitude, low-frequency power. For all channels combined (mean +/- SD), total (-33+/-7%), delta (-47+/-12%), theta (-23+/-12%), and alpha (-21+/-6%) power decreased after the noxious stimulus (P < 0.001); beta power was unchanged. At 0.9 MAC, total (-35+/-5%), delta (-42+/-7%), theta (-35+/-8%), and alpha (-23+/-11%) power decreased after the noxious stimulus (P < 0.001); beta power was unchanged. At 1.1 MAC only one site, and at 1.4 MAC, no site, had decreased power after the noxious stimulus.

CONCLUSIONS

Isoflurane blunted EEG and midbrain reticular formation-thalamus activation response to noxious stimulation at concentrations (1.1 MAC or greater) necessary to prevent movement that occurred after noxious stimulation. It is unknown whether this is a direct effect or an indirect effect via action in the spinal cord.

摘要

背景

包括异氟烷在内的麻醉剂会抑制脑电图（EEG）。关于异氟烷对EEG以及对有害刺激的皮层下电活动反应的定量影响，人们了解甚少。作者推测，异氟烷在低于抑制运动所需浓度时，会抑制EEG结果以及对有害刺激的皮层下反应。此外，确定区域差异可能有助于阐明麻醉作用部位。

方法

用异氟烷麻醉10只山羊，使用有害机械刺激确定最低肺泡浓度（MAC）。将深度电极插入中脑网状结构和丘脑。置于颅骨骨膜的针电极测量双额和双侧半球EEG。在四个麻醉浓度（0.6、0.9、1.1和1.4 MAC）下分别施加有害刺激。

结果

在异氟烷浓度为0.6 MAC时，有害刺激激活了中脑网状结构、丘脑和双额-半球区域，表现为高振幅、低频功率降低。对于所有通道综合来看（平均值±标准差），有害刺激后总功率（-33±7%）、δ波功率（-47±12%）、θ波功率（-23±12%）和α波功率（-21±6%）降低（P<0.001）；β波功率未改变。在0.9 MAC时，有害刺激后总功率（-35±5%）、δ波功率（-42±7%）、θ波功率（-35±8%）和α波功率（-23±11%）降低（P<0.001）；β波功率未改变。在1.1 MAC时，只有一个部位，而在1.4 MAC时，没有部位在有害刺激后功率降低。