人体血液灌注和代谢产热对低温手术过程的影响

Influence of blood perfusion and metabolic heat generation on cryosurgery

使用有限元方法研究了人体血液灌注和代谢产热对低温手术过程中组织温度场的影响.结果表明:一旦引入上述两种因素的影响后,即相当于在经典的传热方程中增加了非线性热源项;该热源项的出现,明显减慢了低温手术过程中冷刀附近组织的降温速率,增加了局部位置组织经历的温度梯度;不仅减慢了冷刀周围组织冻结面的生长速度,而且减小了手术过程中冰球的最大半径.该结果对低温手术的临床应用具有参考价值.

The influences of blood perfusion and metabolic heat generation on the distributions of the temperature and the thermal gradient, and on the growth of the frozen region are studied by using the commercial FEA （finite element analysis） software-Ansys （Version 7.0）. The target tissue is treated as non-ideal material freezing over a temperature range, and the thermophysical nonlinear problem is solved. The enthalpy method and the finite element scheme are applied to solve the multidimensional phase change problem in cryosurgery. The results indicate that, when the source term composed by blood perfusion and metabolic heat generation are taken into consideration, the temperature around the cryoprobe is apparently higher than that of the case without consideration of the source term at the corresponding time, and furthermore, the maximal radius of the ice ball during the whole process of cryosurgery is also markedly decreased. So the vitro experiments will do little to optimize the process of cryosurgery or the design of a cryoprobe, the corresponding vivo experiments should be performed instead. The results are very meaningful for controlling and optimizing the practical cryosurgery.