Petrofsky J, Bains G, Prowse M, Gunda S, Berk L, Raju C, Ethiraju G, Vanarasa D, Madani P
Department of Physical Therapy, Loma Linda University, Loma Linda, CA 92350, USA.
J Med Eng Technol. 2009;33(7):532-7. doi: 10.1080/03091900902952683.
Pennes first described a model of heat transfer through the limb based only on calories delivered from a heat source, calories produced by metabolism and skin blood flow. The purpose of this study was to determine the effect of a moist versus a dry heat source on the skin in eliciting a blood flow response to add data to this model. Ten subjects were examined, both male and female, with a mean age of 32.5 +/- 11.6 years, mean height of 172.8 +/- 12.3 cm, and mean weight of 77.6 +/- 19.5 kg. Skin temperature was measured by a thermocouple placed on the skin and skin blood flow measured by a laser Doppler flow meter. The results of the experiments using a dry heat pack (commercially available chemical 42 degrees C cell dry heat source), moist hydrocollator pack (72.8 degrees C) separated from the skin by eight layers of towels, and whirlpool at 40 degrees C, showed that moist heat caused a significantly higher skin blood flow (about 500% greater) than dry heat (p < 0.01). Most of the greater increase in skin blood flow with moist heat was due to the greater rate of rise of skin temperature with moist versus dry heat while some of the increase in blood flow was due to the moisture itself. This could either be related to the greater heat flux across the skin with moist air or due to changing the ionic environment around skin thermo receptors by keeping the skin moist during heating. Skin thermo receptors are believed to be temperature sensitive calcium gated channels in endothelial cells which couple calcium influx to a release of nitric oxide. If true, reducing moisture in the skin might have the effect of altering ionic flux through these receptors. A correct model of skin heat flux should therefore take heat moisture content into consideration.
彭尼斯首先描述了一种通过肢体的热传递模型，该模型仅基于来自热源的热量、新陈代谢产生的热量以及皮肤血流量。本研究的目的是确定湿热源与干热源对皮肤的影响，以引发血流反应，从而为该模型添加数据。对10名受试者进行了检查，受试者包括男性和女性，平均年龄为32.5±11.6岁，平均身高为172.8±12.3厘米，平均体重为77.6±19.5千克。通过置于皮肤上的热电偶测量皮肤温度，并通过激光多普勒流量计测量皮肤血流量。使用干热敷袋（市售42摄氏度化学干热源）、用八层毛巾与皮肤隔开的湿水胶体热敷袋（72.8摄氏度）以及40摄氏度的漩涡浴进行实验的结果表明，与干热相比，湿热导致的皮肤血流量显著更高（约高出500%）（p<0.01）。湿热导致皮肤血流量增加幅度更大，主要是因为与干热相比，湿热时皮肤温度上升速度更快，而血流量增加的部分原因是水分本身。这可能要么与潮湿空气中穿过皮肤的更大热通量有关，要么是由于在加热过程中保持皮肤湿润改变了皮肤热感受器周围的离子环境。皮肤热感受器被认为是内皮细胞中对温度敏感的钙门控通道，它将钙内流与一氧化氮的释放联系起来。如果这是真的，减少皮肤中的水分可能会改变通过这些感受器的离子通量。因此，一个正确的皮肤热通量模型应该考虑热的含水量。
