Takasu Akira, Sakamoto Toshihisa, Okada Yoshiaki
Department of Traumatology and Critical Care Medicine, National Defense Medical College, Saitama, Japan.
J Trauma. 2006 Dec;61(6):1330-5. doi: 10.1097/01.ta.0000245980.12711.6a.
Rapid induction of hypothermia has been shown to improve survival in uncontrolled hemorrhagic shock (UHS) rat studies. We hypothesized that prolonged induction of hypothermia would be equally beneficial for survival during UHS.
Light anesthesia was induced with halothane in 30 rats, and spontaneous breathing was maintained. Rectal temperature (Tr) was monitored and maintained at 38 degrees C. UHS was induced by blood withdrawal of 2.5 mL/100 g during a 15-minute period, followed by 75% tail amputation. Immediately after cutting the tail, rats were randomized into three groups of 10 rats each: Group 1, maintained at Tr 38 degrees C; group 2, passively cooled to 34 degrees C by exposure to room temperature (23 degrees C); and group 3, actively cooled to 34 degrees C by applying alcohol to the skin and under an electric fan. Next, rats were controlled at each target Tr and observed without fluid resuscitation until either death or a maximum of 240 minutes.
Cooling rate was -0.09 +/- 0.01 degrees C/min in group 2 and -0.36 +/- 0.9 degrees C/min in group 3 (p < 0.01). Mean survival time was 72 +/- 21 minutes in group 1 (38 degrees C), and was nearly doubled by hypothermia to 132 +/- 62 minutes for group 2 (p < 0.01 vs. group 1) and 150 +/- 69 minutes for group 3 (p < 0.01 vs. group 1). No significant difference in survival was noted between groups 2 and 3. Additional blood loss from the tail stump did not differ significantly between groups.
Therapeutic mild hypothermia, induced either slowly (approximately -0.1 degrees C/min) or rapidly (approximately -0.4 degrees C/min) prolongs survival during lethal UHS in rats.
在非控制性出血性休克（UHS）大鼠研究中，快速诱导低温已被证明可提高生存率。我们假设延长低温诱导时间对UHS期间的生存同样有益。
用氟烷对30只大鼠进行轻度麻醉，并维持自主呼吸。监测直肠温度（Tr）并维持在38℃。在15分钟内通过抽取2.5 mL/100 g血液诱导UHS，随后进行75%的尾部截肢。切断尾巴后，大鼠立即随机分为三组，每组10只：第1组，维持Tr 38℃；第2组，通过暴露于室温（23℃）被动冷却至34℃；第3组，通过在皮肤上涂抹酒精并置于电风扇下主动冷却至34℃。接下来，将大鼠控制在每个目标Tr，在不进行液体复苏的情况下观察，直至死亡或最长观察240分钟。
第2组的降温速率为-0.09±0.01℃/分钟，第3组为-0.36±0.9℃/分钟（p<0.01）。第1组（38℃）的平均生存时间为72±21分钟，低温使第2组的平均生存时间几乎翻倍，达到132±62分钟（与第1组相比，p<0.01），第3组为150±69分钟（与第1组相比，p<0.01）。第2组和第3组之间的生存率无显著差异。各组之间尾部残端的额外失血量无显著差异。
在大鼠致死性UHS期间，缓慢（约-0.1℃/分钟）或快速（约-0.4℃/分钟）诱导的治疗性轻度低温均可延长生存时间。
