HEAT-BALANCE AND DISTRIBUTION DURING THE CORE-TEMPERATURE PLATEAU IN ANESTHETIZED HUMANS
HEAT-BALANCE AND DISTRIBUTION DURING THE CORE-TEMPERATURE PLATEAU IN ANESTHETIZED HUMANS
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DOI：
10.1097/00000542-199509000-00007
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发表时间：
1995-09-01
期刊：
影响因子：
8.8
通讯作者：
DECHERT, M
中科院分区：
文献类型：
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作者：
KURZ, A;SESSLER, DI;DECHERT, M
背景：一旦触发，术中热调节性血管收缩在防止进一步低温方面非常有效。保护作用来自血管收缩引起的皮肤热损失的减少和体热分布的改变。然而，每种机制的独立贡献尚未量化。因此，我们评估了在核心温度平台期间身体内的整体热平衡和热量分布。方法：用异丙酚和异氟醚麻醉9名不穿衣服的男性志愿者，保持在大约22摄氏度的环境中，在血管收缩前监测约2小时，随后监测3小时，通过皮肤热损失（热神经传感器）和代谢热产生（耗氧量）的差异来确定总体热平衡。手臂和腿部组织热含量由19个肌内温度、10个皮肤温度和“深”脚温度测定。通过实际变化（食管远端温度变化乘以人体组织比热和躯干和头的重量）减去该区域的预期变化（总体热平衡乘以躯干和头的重量）来计算血管收缩对躯干和头部的限制热量；该结果代表了核心热量超过基于整体热平衡的预期量，假设这种变化在全身均匀分布。结果：血管收缩和被动组织冷却减少了热损失，但没有达到产热的水平，因此，在整个研究中，热损失超过了代谢产热。预收缩期2 h内，岩心温度下降约1.3℃；然而，在随后的3小时内，核心温度几乎保持不变。在血管收缩后的3小时内，手臂和腿部的热量含量减少了57 +/- 3 kcal，血管收缩使躯干和头部的热量减少了22 +/- 8 kcal。结论：这些结果证实了热调节性血管收缩在预防额外的核心低温中的作用。减少皮肤热损失和限制代谢热到核心热室有助于高原。
Background: Once triggered, intraoperative thermoregulatory vasoconstriction is remarkably effective in preventing further hypothermia. Protection results from both vasocanstriction-induced decrease in cutaneous heat loss and altered distribution of body heat. However, the independent contributions of each mechanism have not been quantified. Accordingly, we evaluated overall heat balance and distribution of heat within the body during the core-temperature plateau.Methods: Nine minimally clothed male volunteers were anesthetized with propofol and isoflurane and maintained in an approximate to 22 degrees C environment, They were monitored for approximate to 2 h before vasoconstriction and for 3 h subsequently, Overall heat balance was determined from the difference between cutaneous heat loss (thermal nux transducers) and metabolic heat production (oxygen consumption). Arm and leg tissue heat contents were determined from 19 intramuscular temperatures, ten skin temperatures, and ''deep'' foot temperature. Heat constrained by vasoconstriction to the trunk and head was calculated by subtracting the expected change in that region (overall heat balance multiplied by the fractional weight of the trunk and head) from the actual change (change in distal esophageal temperature multiplied by the specific heat of human tissue and the weight of the trunk and head); the result represents the amount by which core heat exceeded that which would be expected based on overall heat balance, assuming that the change was evenly distributed throughout the body.Results: Vasoconstriction and passive tissue cooling decreased heat loss but not to the level of heat production, Consequently, heat loss exceeded metabolic heat production throughout the study. Core temperature decreased approximate to 1.3 degrees C during the 2-h prevasoconstriction period; however, core temperature remained virtually constant during the subsequent 3 h. In the 3 h after vasoconstriction, arm and leg heat content decreased 57 +/- 3 kcal, and vasoconstriction constrained 22 +/- 8 kcal to the trunk and head.Conclusions: These results confirm the efficacy of thermoregulatory vasoconstriction in preventing additional core hypothermia. Decreased cutaneous heat loss and constraint of metabolic heat to the core thermal compartment contributed to the plateau.