Time-dependent changes in cerebral and cardiovascular parameters in isoflurane-nitrous oxide-anesthetized dogs.
Time-dependent changes in cerebral and cardiovascular parameters in isoflurane-nitrous oxide-anesthetized dogs.
复制标题
异氟烷-笑气麻醉狗的大脑和心血管参数随时间变化。
作者：
D. M. Turner;N. Kassell;T. Sasaki;Y. Comair;D. Boarini;D. O. Beck
本研究的目的是研究异氟醚-氧化亚氮麻醉对脑血流量和代谢以及心血管参数的时间依赖性影响。采用0.8%异氟烷(约1.3 MAC（最低麻醉浓度）、70%氧化亚氮和30% O2麻醉11只15公斤重的杂种狗，用泮库溴铵麻痹。从麻醉诱导后2小时开始，每隔30分钟测量6次血流（采用放射性微球技术）和脑血管及心血管参数。在本实验中，脑血流量在麻醉诱导后2小时显著升高，但随后在研究的2个半小时内逐渐下降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下降和脑血管阻力的不断上升。流向中枢神经系统以外器官的血流量逐渐减少，但组织之间的差异更大。平均动脉压略有升高，外周血管阻力几乎增加一倍，但心脏指数、心脏功、每搏量均逐渐下降。我们得出结论，异氟烷-氧化亚氮麻醉对狗产生显著的脑血管扩张，但这种效果随着时间的推移而减弱。这些随时间变化的循环变化值得在人类中进一步研究。
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.