Study On The Sticking Mechanism Of Porcine Liver Tissue Onto The ACTIV Eelectrode Surface In Electrosurgical Unit Under Coagulation Mode

Because of its fast cutting speed, good hemostatic effect and advantage of sterilization, electrosurgical unit (ESU) has gradually replace traditional surgical knife became a widely used electrosurgical instrument in surgery. Despite the thermal effect of biological tissue produced by ESU could be achieved on tissue cutting and hemostasis, but which also could lead to the occurrence of burned tissue sticking on the surface of active electrode. Once tissue stuck on the active electrode surface may cause the increase of resistance of entire current loop and the decrease of current density of active electrode surface and then result in cutting hard and inadequate coagulation. At present, the study on the tissue sticking behaviors of electrosurgical instrument have not yet been fully developed, and the mechanism of formation and binding mechanism of stuck tissue on the surface of the electrosurgical instrument is still not clear yet. Therefore, study on the tissue sticking behaviors of active electrode of ESU can not only help in the understanding of the interaction between the surface of electrosurgical instrument and tissue during the operation, but also be of great importance to develop a new generation of anti-stick ing active electrode and improve the quality of operation.In this study, the tissue sticking behaviors on 304 stainless steel active electrodes under coagulation mode has been investigated using a self-designed electrosurgical unit test device. Ex vivo porcine liver was used as tissue sample. The morphologies, compositions and mechanical properties of stuck tissue and active electrode interface were characterized by means of scanning electron microscope(SEM), energy spectrometer(EDX), X-ray diffraction analysis(XRD), Fourier transform infrared spectroscopy(FTIR), pro filo meter and mechanical testing system, et al, aiming to explore the tissue sticking mechanism and the key factors influencing the tissue sticking behaviors of active electrode. Main results and conclusions were drawn as follows:(1)Results showed that there existed obvious differences in the tissue sticking behaviors upon active electrode surfaces between the coagulation process and heating treatment. The stuck tissue formed upon active electrode surface during the electrosurgical cutting process was not due to the thermal decomposition of tissue directly, but gasification of bio-tissue gathered on the electrode surface and became the stuck tissue. The alternating electric field was most likely to affect the motions of charged particles within the gasification tissue during electrosurgical cutting process, which may cause the oscillation of charged particles in the tissue-electrode interface and make the gasification tissue form a dense stuck tissue layer upon electrode surface like a process of spray.(2)With increase of cutting time, the thickness of stuck tissue layer upon electrode surface increased, stuck tissue-electrode interface was composed of a linear shaped gradually became blurred, surface roughness of electrode and diffusion of electrode substrate elements aggravated ceaselessly, the critical load of the failure of stuck tissue was also increasing. The micro melting caused by arc discharge was the main reason for the surface roughness and the diffusion of substrate elements of electrode, in which, the surface roughness would increase the mechanical binding of stuck tissue-electrode interface while the diffusion of substrate elements would broaden the stuck tissue-electrode interface, both would increase the binding strength of stuck tissue.(3)Compared to 304 stainless steel electrode with a relative low melting point, the stuck tissue upon tungsten electrode with a high melting point had smaller binding strength and easier to be removed. It seems that the melting point of electrode has a significant influence on the tissue sticking behavior. To utilize electrode materials with high melting point could help prevent the electrode surface from micro-melting, inhibit the occurrence of surface roughness and diffusion of substrate elements of electrode and then alleviate the tissue sticking upon electrode surface.