Antognini J F, Lewis B K, Reitan J A
Department of Anesthesiology, University of California, Davis 95616-8634.
Anesth Analg. 1994 Nov;79(5):980-2. doi: 10.1213/00000539-199411000-00027.
Over the 38-28 degrees C range, changes in minimum alveolar anesthetic concentration (MAC) parallel changes in lipid solubility of the anesthetics studied. We hypothesized that there would be minimal change in N2OMAC, since N2O lipid solubility is relatively unaltered by temperature changes. We determined N2OMAC in rats using a hyperbaric chamber. In Group N (normothermia, n = 10) rectal temperature was maintained at 37.5 +/- 1 degrees C (mean +/- SD). In Group H (hypothermia, n = 9) temperature was maintained at 29.7 +/- 1.8 degrees C. The hyperbaric chamber was pressurized with N2O and oxygen partial pressure was 0.4 +/- 0.1 atm. Chamber pressure was adjusted approximately 15% up or down, stabilized for approximately 15 min, and the noxious stimulus (electrical current) was applied. This process was continued until two N2O partial pressures were determined which just prevented and just permitted gross, purposeful movement. Nitrous oxide MAC for Group N and Group H were 1.9 +/- 0.2 atm and 1.6 +/- 0.2 atm, respectively, P < 0.01. Temperature and MAC correlated: r = 0.59, P < 0.01. We conclude that hypothermia minimally decreases N2OMAC, which is consistent with the effects of hypothermia on N2O solubility in lipid membranes.
在38 - 28摄氏度范围内，所研究麻醉剂的最低肺泡麻醉浓度（MAC）变化与麻醉剂脂溶性的变化呈平行关系。我们假设笑气MAC变化极小，因为笑气的脂溶性相对不受温度变化影响。我们使用高压舱测定大鼠的笑气MAC。在N组（正常体温，n = 10）中，直肠温度维持在37.5±1摄氏度（平均值±标准差）。在H组（低温，n = 9）中，温度维持在29.7±1.8摄氏度。用笑气给高压舱加压，氧分压为0.4±0.1个大气压。将舱压上下调整约15%，稳定约15分钟，然后施加有害刺激（电流）。持续这个过程，直到确定两个笑气分压，一个刚好能防止、另一个刚好能允许明显的有目的运动。N组和H组的氧化亚氮MAC分别为1.9±0.2个大气压和1.6±0.2个大气压，P < 0.01。温度与MAC相关：r = 0.59，P < 0.01。我们得出结论，低温使笑气MAC轻度降低，这与低温对笑气在脂质膜中溶解度的影响一致。
