Turner D M, Kassell N F, Sasaki T, Comair Y G, Boarini D J, Beck D O
Neurosurgery. 1984 Feb;14(2):135-41. doi: 10.1227/00006123-198402000-00003.
The purpose of this study was to examine the time-dependent effects of isoflurane-nitrous oxide anesthesia on cerebral blood flow and metabolism and on cardiovascular parameters. Eleven 15-kg mongrel dogs were anesthetized with 0.8% isoflurane (approximately 1.3 MAC (minimal anesthetic concentration], 70% nitrous oxide, and 30% O2 and were paralyzed with pancuronium. Blood flow (using the radioactive microsphere technique) and cerebrovascular and cardiovascular parameters were measured 6 times at 30-minute intervals beginning 2 hours after the induction of anesthesia. In this experiment, cerebral blood flow was markedly elevated at 2 hours after the induction of anesthesia, but then declined progressively by 40 to 50% over the 2 1/2-hour time period investigated, approaching values for normal awake dogs. The decline was accompanied by a progressive decrease in the cerebral metabolic rate of oxygen and a constant rise in cerebrovascular resistance. Blood flow to organs outside the central nervous system declined progressively, but with more variability between tissues. The mean arterial pressure increased slightly, and the peripheral vascular resistance almost doubled, but cardiac index, cardiac work, and stroke volume all decreased gradually. We conclude that isoflurane-nitrous oxide anesthesia produces significant cerebral vasodilatation in dogs, but that this effect diminishes over time. These time-dependent circulatory changes merit further investigation in humans.
本研究的目的是探讨异氟烷 - 氧化亚氮麻醉对脑血流量、脑代谢以及心血管参数的时间依赖性影响。11只体重15千克的杂种犬用0.8%异氟烷（约1.3倍最低肺泡有效浓度[MAC]）、70%氧化亚氮和30%氧气麻醉，并使用泮库溴铵使其麻痹。在麻醉诱导2小时后开始，每隔30分钟测量一次血流量（采用放射性微球技术）以及脑血管和心血管参数，共测量6次。在本实验中，麻醉诱导2小时后脑血流量显著升高，但在随后2个半小时的研究时间段内逐渐下降40%至50%，接近正常清醒犬的值。这种下降伴随着脑氧代谢率的逐渐降低以及脑血管阻力的持续升高。中枢神经系统以外器官的血流量逐渐下降，但不同组织之间的变化更大。平均动脉压略有升高，外周血管阻力几乎翻倍，但心脏指数、心脏做功和每搏量均逐渐下降。我们得出结论，异氟烷 - 氧化亚氮麻醉在犬中可产生显著的脑血管扩张，但这种效应会随时间减弱。这些时间依赖性循环变化值得在人类中进一步研究。
