Research On A Bipolar Electro-coagulation Generator For Biological Tissue And Its Experimental Study

As a one of modern surgical methods, the technology of bipolar electro-surgery hassuch advantages as fast hemostasis, high efficiency and small thermal damage, and thistechnology has been widely used in laparoscopic surgery and open surgery. Currently,oversea researchers have made a lot of highlight studies on the mechanism and processingof the bipolar electro-coagulation. Up to day, the advanced bipolar electro-coagulationsystems produced by foreign companies can seal diameter vessels of maximum7mm andwith about2.0-3.5mm thermal damage. However, the research of the bipolar electriccoagulation system in China has just started, the thermal damage of the domesticgenerator is generally in the size of4-10mm, and the study of mechanism forelectro-coagulation is rarely reported. In short, there is a big gap in the research ofgenerator system between domestic bipolar electro-coagulation generator and that ofabroad. Therefore, research on bipolar electro-coagulation power systems and the tissueeffect of the bipolar electro-coagulation process have very important significance.For that reason, several key factors which influence the effect of bipolarelectro-coagulation, skin effect, the characteristics of the cellular temperature andtemperature-impedance properties of biological tissue, are analyzed firstly in thisdissertation. It is considered that skin effect affect tissue electro-coagulation order, thecharacteristics of the cellular temperature effect the optimal temperature ofelectro-coagulation; the properties of tissue temperature-impedance influence tissueimpedance change with temperature. By analyzing the mechanism of bipolarelectro-coagulation, basic parameters of the research power system and the designsolution of the system are determined.Based on the design parameters and system solution for this research polarelectro-coagulation power system, the hardware circuits and its control system aredevised. Series resonant circuit and RCD buffer circuit are adopted in the main circuit toreduce the losses of switch turn on or off. The current control and power control systemsare designed to avoid the occurrence of tissue carbide by controlling the output power.Finally, utilizing the designed the power system, the thermal damage experiments ofmuscle tissue based on porcine model are carried out. Four electric coagulation processesare partitioned according to the voltage variation characteristics of the muscle tissuebetween the poles in the process of the bipolar electric coagulation. Based on thecharacteristics of the transition voltage, the control program of the output for power control is devised to improve the control system. By conducting the experiments forvessel coagulation of the rabbit model, some rules of voltage and frequency change ontissue coagulation is summarized. By contrast to the tissue effect of a domestic converterwith intermittent output waveform with high-voltage and the continue output waveformwith low-voltage, it is found that continue output is suitable to vessel electric coagulation.The experiments verify the feasibility of the developed power system, summarizesthe influence of the voltage and frequency characteristics to the biological tissue(especially blood vessels). This study provides some basic experimental data for furtherimprovement of the power system and the equipment of bipolar electro-coagulation.