Chernow B, Lake C R, Zaritsky A, Finton C K, Casey L, Rainey T G, Fletcher J R
Crit Care Med. 1983 Sep;11(9):677-80. doi: 10.1097/00003246-198309000-00001.
Hypothermia occurs frequently in the critically ill patient, yet little is known about the endogenous catecholamine response to this stress. To study this problem, we measured heart rate (HR), mean arterial blood pressure (MAP), and plasma levels of norepinephrine (NE) and epinephrine (Epi) in subhuman primates (baboons) during progressive hypothermia from 37 degrees to 29 degrees C and then during rewarming to 37 degrees C. As the core temperature decreased from 37 degrees to 33 degrees C, HR and MAP increased significantly (p less than 0.05), but as core temperature further decreased from 33 degrees to 29 degrees C, the HR and MAP fell to prehypothermic levels. Plasma concentrations of NE and Epi increased significantly (p less than 0.01) as core temperature fell from 37 degrees to 31 degrees C, but as core temperature dropped from 31 degrees to 29 degrees C, plasma NE and Epi levels decreased towards prehypothermic concentrations. These findings indicate that the sympathetic nervous system (SNS) responds quickly to hypothermia but may be "switched off" at a threshold temperature of about 29 degrees C. We speculate that hypotensive patients with temperatures less than or equal to 29 degrees C may benefit from infusions of exogenous catecholamines, especially if there have been only minimal benefits achieved with conventional therapy such as fluids, and an increase in ambient temperature.
体温过低在危重病患者中频繁发生，但对于内源性儿茶酚胺对这种应激的反应却知之甚少。为了研究这个问题，我们在亚人类灵长类动物（狒狒）体温从37摄氏度逐渐降低至29摄氏度然后再复温至37摄氏度的过程中，测量了心率（HR）、平均动脉血压（MAP）以及去甲肾上腺素（NE）和肾上腺素（Epi）的血浆水平。随着核心体温从37摄氏度降至33摄氏度，HR和MAP显著升高（p<0.05），但当核心体温进一步从33摄氏度降至29摄氏度时，HR和MAP降至体温过低前的水平。随着核心体温从37摄氏度降至31摄氏度，血浆中NE和Epi的浓度显著升高（p<0.01），但当核心体温从31摄氏度降至29摄氏度时，血浆NE和Epi水平朝着体温过低前的浓度下降。这些发现表明，交感神经系统（SNS）对体温过低反应迅速，但可能在约29摄氏度的阈值温度时“关闭”。我们推测，体温小于或等于29摄氏度的低血压患者可能从输注外源性儿茶酚胺中获益，尤其是在诸如补液和提高环境温度等传统治疗仅取得极小益处的情况下。
