Instrumento de medição do coeficiente de transferência de calor por convecção da artéria hepática e da veia porta

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Hepatocellular carcinoma is one of the most common malignancies worldwide. In radiofrequency hepatic ablation, the tumor is heated by means of radio-frequency electrodes, which heats the target tumor. The heat causes necrosis of the malignant tumor. Thus, if the procedure is successful it can cure the patient. Studies have shown that recurrences occur after the treatment and these recurrences occur frequently next to the hepatic artery and portal vein. The recurrences occur due to the high convective loss on these vases. Therefore, convective heat loss does not allow adequate heating of tumors. Simulations have been performed in order to develop a method to cause uniform heating of the tumor. These simulations need the convective heat loss (h) in the vessels of the liver as an important parameter to evaluate different electrode geometries in order to improve the method. Currently, there is no instrument for measuring h in large vessels of the liver. This work proposed, developed and tested an instrument for the measurement of this parameter. Moreover, this work developed a mechanical simulator and validated an equation developed by Consiglieris et al, which determines analytically the value of h. The measurement instrument consisted of circuits for controlling and conditioning the signals, and a flexible heater to be applied on the surface of the vessels. The instrument was tested using a mechanical simulator developed in order to reproduce the flow conditions and the geometry of large vessels in the liver. A flow of 1,5 dm3/min was simulated to mock the typical flow and geometry of the vessels. The average value of h using the experimental apparatus was 2743 56 W/m2.K (p<0.05). The average value of h obtained using Consiglieris equation was of 2136 83 W/m2.K (p<0.05). We concluded that the instrument can probably be used for measuring h in large vessels and that the Consiglieris equation agrees with experimental data.

ASSUNTO(S)

instrumentos e aparelhos cirúrgicos coeficiente de convecção câncer de fígado ablação térmica engenharia eletrica instrumentação biomédica

ACESSO AO ARTIGO

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