Matthew C B, Bastille A M, Gonzalez R R, Sils I V
U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007, USA.
Can J Physiol Pharmacol. 2002 Sep;80(9):925-33. doi: 10.1139/y02-120.
This study examined electrocardiogram (ECG) waveform, heart rate (HR), mean blood pressure (BP), and HR variability as potential autonomic signatures of hypothermia and rewarming. Adult male Sprague-Dawley rats had telemetry transmitters surgically implanted, and 2 weeks were allowed for recovery prior to induction of hypothermia. Rats were lightly anesthetized (sodium pentobarbital, 35 mg/kg i.p.) and placed in a coil of copper tubing through which temperature-controlled water was circulated. Animals were cooled to a core temperature (Tc) of 20 degrees C, maintained there for 30 min, and then rewarmed. Data (Tc, BP, HR from ECG, and 10-s strips of ECG waveforms) were collected every 5 min throughout hypothermia and rewarming. Both HR and BP declined after initial increases with the drop in HR starting at a higher Tc than the drop in BP (29.6 +/- 2.4 degrees C vs. 27.1 +/- 3.3 degrees C, p < 0.05). Animals that were not successfully rewarmed exhibited a significant (p < 0.05) increase in the normalized standard deviation of interbeat intervals (IBI) throughout cooling compared with animals that were successfully rewarmed. The T wave of the ECG increased in amplitude and area with decreasing Tc. T-wave amplitude and IBI variability show potential as predictors of survival in hypothermic victims.
本研究检测了心电图（ECG）波形、心率（HR）、平均血压（BP）以及心率变异性，将其作为体温过低和复温时潜在的自主神经特征。成年雄性Sprague-Dawley大鼠通过手术植入遥测发射器，在体温过低诱导前给予2周恢复时间。大鼠轻度麻醉（腹腔注射戊巴比妥钠，35 mg/kg），置于一根铜管线圈中，温度可控的水在管中循环。将动物冷却至核心温度（Tc）20℃，维持30分钟，然后复温。在整个体温过低和复温过程中，每5分钟收集一次数据（Tc、BP、ECG得出的HR以及10秒的ECG波形条带）。随着体温下降，HR和BP在最初升高后均下降，HR下降时的Tc高于BP下降时的Tc（29.6±2.4℃对27.1±3.3℃，p<0.05）。与成功复温的动物相比，未成功复温的动物在整个降温过程中，心跳间期（IBI）标准化标准差显著增加（p<0.05）。随着Tc降低，ECG的T波振幅和面积增大。T波振幅和IBI变异性有望作为体温过低受害者生存情况的预测指标。
