Baughman V L, Hoffman W E, Thomas C, Miletich D J, Albrecht R F
Department of Anesthesiology, Michael Reese Hospital and Medical Center, Chicago, Illinois 60616.
Anesthesiology. 1990 Jan;72(1):85-94. doi: 10.1097/00000542-199001000-00016.
Using a rat model of incomplete cerebral ischemia the effects of isoflurane (iso) and methohexital (metho) were compared with those of 70% nitrous oxide controls (N2O). Two levels of incomplete cerebral ischemia were produced by right carotid occlusion plus hypotension for 30 min: moderate = 30 mmHg, FIO2 = 0.30; severe = 25 mmHg, FIO2 = 0.20. The iso doses (1 and 2 MAC) and metho doses (0.01 and 0.1 mg.kg-1.min-1) were tested at each ischemic level. These iso and metho doses were selected because without ischemia they produced similar decreases in cerebral oxygen consumption (CMRO2) compared with that produced in N2O controls. In the absence of ischemia, the electroencephalogram (EEG) was suppressed by 0.01 mg.kg-1.min-1 metho and 1 MAC iso and showed burst-suppression with 0.1 mg.kg-1.min-1 metho and 2 MAC iso. The EEG was further depressed by ischemia under all anesthetic conditions. Neurologic outcome was evaluated for 3 days following incomplete cerebral ischemia by using a graded deficit score (0 = normal, 5 = death associated with stroke). Following moderate ischemia all four anesthetic treatments improved outcome compared with N2O controls, but after severe ischemia only 2 MAC iso significantly improved outcome. Neurohistopathology was evaluated on a scale of 0 to 40, 24 h after ischemia. The neurohistopathology score was significantly improved by all four anesthetic treatments compared with N2O following moderate ischemia and was better with 2 MAC iso compared with 0.1 mg.kg-1.min-1 metho after both moderate and severe ischemia. These results show that both iso and metho improve outcome from cerebral ischemia compared with that associated with N2O, but only 2 MAC iso resulted in an improved outcome following severe ischemia. This difference in outcome between the two anesthetics may be related to greater neuronal depression with iso, which may occur with little difference in cerebral metabolic depression.
使用不完全性脑缺血大鼠模型，将异氟烷（iso）和甲己炔巴比妥（metho）的效果与70%氧化亚氮对照组（N2O）进行比较。通过右侧颈动脉闭塞加低血压30分钟产生两种不完全性脑缺血水平：中度=30 mmHg，FIO2 = 0.30；重度=25 mmHg，FIO2 = 0.20。在每个缺血水平测试异氟烷剂量（1和2 MAC）和甲己炔巴比妥剂量（0.01和0.1 mg·kg-1·min-1）。选择这些异氟烷和甲己炔巴比妥剂量是因为在无缺血情况下，与N2O对照组相比，它们使脑氧耗量（CMRO2）产生相似程度的降低。在无缺血时，脑电图（EEG）在甲己炔巴比妥剂量为0.01 mg·kg-1·min-1和异氟烷剂量为1 MAC时受到抑制，在甲己炔巴比妥剂量为0.1 mg·kg-1·min-1和异氟烷剂量为2 MAC时显示爆发抑制。在所有麻醉条件下，缺血都会使脑电图进一步受到抑制。在不完全性脑缺血后3天，使用分级缺陷评分（0 =正常，5 =与中风相关的死亡）评估神经功能结局。与N2O对照组相比，中度缺血后所有四种麻醉处理均改善了结局，但重度缺血后只有2 MAC异氟烷显著改善了结局。在缺血24小时后，以0至40的评分标准评估神经组织病理学。与N2O相比，中度缺血后所有四种麻醉处理均使神经组织病理学评分显著改善，在中度和重度缺血后，2 MAC异氟烷的评分优于0.1 mg·kg-1·min-1甲己炔巴比妥。这些结果表明，与N2O相关情况相比，异氟烷和甲己炔巴比妥均改善了脑缺血的结局，但只有2 MAC异氟烷在重度缺血后使结局得到改善。两种麻醉剂在结局上的这种差异可能与异氟烷引起的更强的神经元抑制有关，这可能在脑代谢抑制差异不大的情况下发生。
