Kastella K G, Fox J R
Biophys J. 1971 Jun;11(6):521-39. doi: 10.1016/S0006-3495(71)86232-X.
Several mathematical descriptions of heat transport in perfused tissues have been proposed but have not been thoroughly tested under conditions of time-varying temperatures. Data was obtained by measuring the response of brain temperature to step changes in temperature of chronically implanted thermodes in conscious baboons. These responses were compared to numerical solutions of an equation expressing heat transport in terms of conduction in the tissue and convection due to capillary blood flow. Good agreement between experimental and theoretical curves was obtained for values of k (thermal diffusivity) of 0.0017-0.0021 cm(2)/sec and ø (blood flow per unit volume of tissue) of 0.3-0.7 cm(3)/cm(3)-min. The predicted temperature response at a given tissue location was not greatly affected either by changes in k and ø over the physiological range, or by small errors in describing experimental geometry. However, inaccuracies in describing boundary locations or failing to account for the relatively avascular scar tissue around the thermode changed the value of ø needed to fit the data by as much as 50%. Thus, we conclude that the model described in this paper can be used for a description of thermal gradients surrounding a thermode but extreme caution should be exercised if such a model is used to quantitatively evaluate blood flow.
已经提出了几种关于灌注组织中热传递的数学描述，但尚未在随时间变化的温度条件下进行全面测试。通过测量清醒狒狒中慢性植入的热电极温度的阶跃变化时脑温的响应来获取数据。将这些响应与一个方程的数值解进行比较，该方程根据组织中的传导和毛细血管血流引起的对流来表达热传递。对于热扩散率k值为0.0017 - 0.0021 cm²/秒和组织单位体积血流量ø值为0.3 - 0.7 cm³/cm³ - 分钟，实验曲线和理论曲线之间获得了良好的一致性。在给定组织位置的预测温度响应，在生理范围内k和ø的变化，或者描述实验几何形状的小误差，都不会对其产生太大影响。然而，描述边界位置的不准确或未考虑热电极周围相对无血管的瘢痕组织，会使拟合数据所需的ø值变化高达50%。因此，我们得出结论，本文所述模型可用于描述热电极周围的热梯度，但如果使用该模型来定量评估血流量，则应极其谨慎。
