Alkire M T, Haier R J, Shah N K, Anderson C T
Department of Anesthesiology, University of California-Irvine Medical Center, Orange 92668, USA.
Anesthesiology. 1997 Mar;86(3):549-57. doi: 10.1097/00000542-199703000-00006.
Although the anesthetic effects of the intravenous anesthetic agent propofol have been studied in the living human brain using brain imaging technology, the nature of the anesthetic state evident in the human brain during inhalational anesthesia remains unknown. To examine this issue, the authors studied the effects of isoflurane anesthesia on human cerebral glucose metabolism using positron emission tomography (PET).
Five volunteers each underwent two PET scans; one scan assessed awake-baseline metabolism and the other scan assessed metabolism during isoflurane anesthesia titrated to the point of unresponsiveness (means +/- SD; expired = 0.5 +/- 0.1%). Scans were obtained with a GE2048 scanner (4.5-mm resolution-FWHM) using the 18fluorodeoxyglucose technique.
Awake whole-brain glucose metabolism averaged 6.9 +/- 1.5 mg.100 g-1.min-1 (means +/- SD). Isoflurane reduced whole-brain metabolism 46 +/- 11% to 3.6 +/- 0.3 mg.100 g-1.min-1 (P < or = 0.005). Regional metabolism decreased fairly uniformly throughout the brain, and no evidence of any regional metabolic increases were found in any brain region for any participant. A region-of-interest analysis showed that the pattern of regional metabolism evident during isoflurane anesthesia was not significantly different from that seen when participants were awake.
These data clarify that the anesthetic state evident in the living human brain during unresponsiveness induced with isoflurane is associated with a global, fairly uniform, whole-brain glucose metabolic reduction of 46 +/- 11%.
尽管已使用脑成像技术在活体人类大脑中研究了静脉麻醉剂丙泊酚的麻醉效果，但吸入麻醉期间人类大脑中明显的麻醉状态的本质仍不清楚。为了研究这个问题，作者使用正电子发射断层扫描（PET）研究了异氟烷麻醉对人类大脑葡萄糖代谢的影响。
五名志愿者每人接受两次PET扫描；一次扫描评估清醒基线代谢，另一次扫描评估异氟烷麻醉至无反应状态（平均值±标准差；呼出浓度 = 0.5±0.1%）时的代谢。使用GE2048扫描仪（4.5毫米分辨率 - 半高宽）通过18氟脱氧葡萄糖技术进行扫描。
清醒时全脑葡萄糖代谢平均为6.9±1.5毫克·100克-1·分钟-1（平均值±标准差）。异氟烷使全脑代谢降低46±11%至3.6±0.3毫克·100克-1·分钟-1（P≤0.005）。全脑区域代谢相当均匀地下降，且未在任何参与者的任何脑区发现区域代谢增加的证据。感兴趣区域分析表明，异氟烷麻醉期间明显的区域代谢模式与参与者清醒时所见模式无显著差异。
这些数据表明，异氟烷诱导的无反应状态下活体人类大脑中明显的麻醉状态与全脑葡萄糖代谢整体、相当均匀地降低46±11%有关。
