Department of Emergency Medicine, Medical University of Vienna, Austria.
Resuscitation. 2010 Feb;81(2):242-7. doi: 10.1016/j.resuscitation.2009.11.002. Epub 2009 Dec 16.
To identify the optimal level of hypothermia during cardiac arrest, just prior to resuscitation with an extracorporeal cooling system and without fluid overload, for neurological outcome at day 9 in pigs.
In a prospective randomised laboratory investigation, 24 female Large White pigs (31-38 kg) underwent ventricular-fibrillation cardiac arrest for 15 min, followed by 1 min, 3 min or 5 min (n=8 per group) of 4 degrees C cooling with an extracorporeal cooling system via an aortic balloon catheter and resuscitation with cardiopulmonary bypass. Sixty minutes following induction of cardiac arrest, defibrillation attempts were started. Mild hypothermia (34.5 degrees C) and intensive care were continued for 20 h and final outcome was evaluated after 9 days.
Brain temperature decreased from 38.5 degrees C to 30.4+/-1.6 degrees C within 221+/-81 s in the 1-min group; to 24.2+/-4.6 degrees C within 375+/-127 s in the 3-min group; and to 18.8+/-4.0 degrees C within 450+/-121 s in the 5-min group. Restoration of spontaneous circulation was achieved in seven (1-min group), six (3-min group) and six (5-min group) animals (p=0.78), whereas survival to 9 days was only achieved in six, three and three animals in each group (p=0.22), respectively.
An extracorporeal cooling system rapidly induced brain hypothermia following prolonged normovolaemic cardiac arrest in pigs. Difference in outcome was not statistically significant amongst the three groups with various levels of hypothermia (30 degrees C, 24 degrees C and 18 degrees C) during cardiac arrest prior to resuscitation; however, the animals with the least temperature reduction showed a trend to better survival at 9 days. Further studies are necessary to investigate optimised methods for induction, as well as level, of cerebral hypothermia.
在使用体外冷却系统复苏之前，确定心脏骤停期间的最佳低温水平，以实现无液体过载情况下的神经功能恢复，本研究的观察终点为猪模型在心脏骤停后 9 天的神经功能。
本研究为前瞻性随机实验室研究，24 头雌性大白猪（31-38kg）经历心室颤动诱导的心脏骤停 15min，随后使用主动脉球囊导管进行体外冷却系统冷却 1min、3min 或 5min（每组 8 头），将核心温度降至 4°C，随后进行心肺复苏。心脏骤停诱导 60min 后开始除颤尝试。轻度低温（34.5°C）和重症监护持续 20h，9 天后评估最终结果。
1min 组猪的脑温在 221+/-81s 内从 38.5°C降至 30.4+/-1.6°C；3min 组在 375+/-127s 内降至 24.2+/-4.6°C；5min 组在 450+/-121s 内降至 18.8+/-4.0°C。7 只（1min 组）、6 只（3min 组）和 6 只（5min 组）动物恢复自主循环（p=0.78），而每组仅 6 只、3 只和 3 只动物存活至 9 天（p=0.22）。
在猪模型长时间的血流动力学正常的心脏骤停后，使用体外冷却系统可以迅速诱导脑低温。在复苏前心脏骤停期间，各组之间存在不同程度的低温（30°C、24°C 和 18°C），但在结果上无统计学差异；然而，体温降低最少的动物在 9 天时的存活率有改善的趋势。需要进一步研究以确定最佳的脑低温诱导和降温方法。
