Tsushima K, Shingu K, Ikeda S, Kimura H, Yamada K, Murao K
Department of Anesthesiology, Kansai Medical University, Osaka, Japan.
Can J Anaesth. 1998 Mar;45(3):240-5. doi: 10.1007/BF03012909.
Suppression of response to a given stimulus by anaesthetics might be considered as a summation of the suppression of basal (pre-stimulus) activity and response capability (increased by stimulus). Anaesthetic suppression of each component in brain and cardiovascular variables by halothane, isoflurane or sevoflurane was compared in cats.
Thirty cats were allocated to one of three groups (n = 10 in each) according to the anaesthetic given. The sciatic nerve was stimulated after maintaining the end-tidal concentration of the anaesthetic at 1.3 or 2.0 MAC for at least 30 min. Cortical electroencephalogram (EEG), multi-unit activity in the mid-brain reticular formation (R-MUA), mean arterial pressure (MAP) and heart rate (HR) were measured before and after electrical sciatic nerve stimulation.
The EEG patterns and R-MUA indicated greater suppression of activity in the brain by isoflurane (31 +/- 4% of awake state at 1.3 MAC, mean +/- SEM) and sevoflurane (38 +/- 5%) than by halothane (61 +/- 5%, P < 0.05), before stimulation. The R-MUA following the stimulation was not different among agents. The MAP and HR were not different among groups before stimulation, but following stimulation were greater in the sevoflurane group (137 +/- 9 and 103 +/- 9 mmHg at 1.3 and 2.0 MAC) than in the halothane group (103 +/- 5 and 76 +/- 3 mmHg, P < 0.05).
Isoflurane and sevoflurane have greater suppressive action on the basal CNS activity than halothane at the same MAC, and that these two anaesthetics have a weak suppressive action on the response capability to peripheral stimulation.
麻醉药对给定刺激反应的抑制可被视为基础（刺激前）活动抑制和反应能力（因刺激而增强）抑制的总和。比较了氟烷、异氟烷或七氟烷对猫脑和心血管变量中各成分的麻醉抑制作用。
根据给予的麻醉药，将30只猫分为三组之一（每组n = 10）。在将麻醉药的呼气末浓度维持在1.3或2.0 MAC至少30分钟后，刺激坐骨神经。在坐骨神经电刺激前后测量皮质脑电图（EEG）、中脑网状结构多单位活动（R-MUA）、平均动脉压（MAP）和心率（HR）。
在刺激前，EEG模式和R-MUA表明，异氟烷（在1.3 MAC时为清醒状态的31±4%，平均值±标准误）和七氟烷（38±5%）对脑活动的抑制作用比氟烷（61±5%，P < 0.05）更强。刺激后的R-MUA在各药物之间没有差异。刺激前各组的MAP和HR没有差异，但刺激后七氟烷组（在1.3和2.0 MAC时分别为137±9和103±9 mmHg）的MAP和HR比氟烷组（103±5和76±3 mmHg，P < 0.05）更高。
在相同MAC下，异氟烷和七氟烷对基础中枢神经系统活动的抑制作用比氟烷更强，并且这两种麻醉药对外周刺激反应能力的抑制作用较弱。
