Rossi G T, Britt R H
Electroencephalogr Clin Neurophysiol. 1984 Feb;57(2):143-55. doi: 10.1016/0013-4694(84)90173-1.
Effects of systemic hypothermia on the brain-stem auditory evoked responses (BAERs) in 4 pentobarbital anesthetized adult cats placed on total cardiopulmonary bypass were investigated. Hypothermia was achieved by slowly cooling the bypass blood through a heat exchanger. Serial BAERs were recorded at 2 min intervals as brain temperature was lowered from 37 to 22 degrees C and then rewarmed over a 1-2 h period. Temperatures were recorded from the brain, esophagus and rectum. Three effects were produced by controlled systemic hypothermia. First, latencies of each component wave (I-V) of the BAER increased exponentially as brain temperature was lowered to 19 degrees C. Latencies of earlier waves (I-III) increased less than those of the later waves (IV-V). Arrhenius plots of inverse latency (rate) versus reciprocal of the absolute temperature generated a family of straight lines of similar slope for each of the 5 component waves of the BAER. The activation energy for each of the 5 BAER waves was derived from the slope of the Arrhenius plot. The mean and standard deviation of the activation energy of all 5 waves was 9.7 +/- 0.5 kcal/mole degree C. The fact that the activation energy was similar for each BAER component wave (I-V) indicated that the increase in latencies for all 5 waves was governed by the same rate-limiting, temperature-dependent process(es). Second, the rise time and duration of each of the component waves of the BAER increased with decreasing temperature. Third, wave amplitudes increased from 37 to 32 degrees C in a quasiparabolic relation and then, decreased at approximately a linear rate. The BAER wave form completely disappeared below 20.3 degrees C. Slow rewarming of the brain to its initial temperature restored the BAER component waves to their original latencies and amplitudes.
研究了全身低温对4只戊巴比妥麻醉下接受完全体外循环的成年猫脑干听觉诱发电位（BAERs）的影响。通过热交换器缓慢冷却体外循环血液来实现低温。当脑温从37℃降至22℃，然后在1 - 2小时内复温时，每隔2分钟记录一次连续的BAERs。记录脑、食管和直肠的温度。控制性全身低温产生了三种效应。首先，随着脑温降至19℃，BAER各成分波（I - V）的潜伏期呈指数增加。早期波（I - III）的潜伏期增加幅度小于后期波（IV - V）。BAER的5个成分波中每个波的逆潜伏期（速率）与绝对温度的倒数的阿累尼乌斯图产生了一系列斜率相似的直线。从阿累尼乌斯图的斜率得出BAER的5个波中每个波的活化能。所有5个波的活化能的平均值和标准差为9.7±0.5千卡/摩尔·℃。每个BAER成分波（I - V）的活化能相似这一事实表明，所有5个波潜伏期的增加受相同的限速、温度依赖性过程控制。其次，BAER各成分波的上升时间和持续时间随温度降低而增加。第三，波幅在37℃至32℃之间呈准抛物线关系增加，然后以近似线性速率下降。在20.3℃以下BAER波形完全消失。将脑缓慢复温至初始温度可使BAER成分波恢复到原来的潜伏期和波幅。
