Development Of High-frequency Electrosurgical System With Vascular Closure Function

After more than 100 years of development,high-frequency electric knife is not limited to simple cutting,electrocoagulation or cauterization functions,but can achieve precise control of output energy for biological tissues in different parts and states.However,domestic electrosurgical technology started late,and it is almost blank in the application fields of vascular closure with complex algorithms.In order to solve this problem,In this thesis we mainly develops an electrosurgical system with high-precision vascular closure function from the functions of monopolar cut,bipolar electrocoagulation and vascular closure.1.Monopolar and bipolar research:Based on the change of water content of biological tissues with temperature,an monopolar cut model with temperature change parameters is proposed,and the accuracy of temperature change parameter model for maximum temperature prediction is improved by 20.1%compared with the fixed parameter model.The effect of monopolar cut under different voltages was studied,and it was found that in the range of 60V to 150V,the surface damage width and the blade damage width continued to rise,while the cutting depth reached the maximum at 120V at a voltage of 13.5mm,which may be due to the saturation of the longitudinal current at this voltage,and the effect of continuing to increase the voltage on longitudinal cutting was not greatly improved.The electrocoagulation range of the bipolar was studied,and the simulation and experiments showed that when the voltage increased from 40V to 60V,the electrocoagulation area of the bipolar increased from 4.975(8(8(8(8~3 to 12.377(8(8(8(8~3,and the pit area after gasification was formed on the surface of the tissue,and when the voltage rose to 90V,the electrocoagulation area decreased to 10.938(8(8(8(8~3,and the carbonization area appeared in the tissue.It may be due to the decrease in conductivity after tissue carbonization,less heat generation,and therefore a decrease in the electrocoagulation area.2.Vascular closure research:Based on the change of impedance with temperature during vascular closure,a vascular model of variable contact resistance layer was constructed.Based on this model,the vascular closure process is divided into three stages:prefusion,fusion and post-fusion according to temperature changes.The time of the pre-fusion stage is 0 to 1.5 seconds,the tissue temperature rises slowly,and the temperature rise is concentrated around the blood vessel wall;the time of the fusion stage is 1.5 seconds to 4.5 seconds,the tissue temperature rises rapidly to 80 to90°C,the temperature rise is concentrated around the contact resistance layer,and the highest temperature rise even exceeds the subsequent stage;the time of the post-fusion stage is 4.5 seconds to 15 seconds,and the tissue temperature is maintained at about 80°C.Based on this,a three-stage vascular closure algorithm was designed,and the impedance threshold of the algorithm was modified experimentally,and 200 ohms,700 ohms and 1100 ohms were selected as the impedance thresholds of the algorithm.3.System design research:Starting from simulation and experiments,the system development of hardware is realized according to actual needs,mainly including DC-DC voltage regulation circuit,DC-AC inverter circuit,and system control circuit.The output of the final designed high-frequency electro-knife system is 380k Hz standard sine wave,the output power of monopolar cut mode is adjustable 0～300W,the bipolar electrocoagulation mode is adjustable 0～100W,the vascular closure mode is 0～150W adjustable,and the output power accuracy is controlled within 5%.After testing,the system modes work well and can meet the actual needs.