Basic Principles and Future Aspects of Thermal Fusion and Electrocoagulation – Experimental studies in in-vitro and in-vivo rodent, porcine and human models

Abstract

Bipolar vessel sealing and electrosurgery in general is pivotal in surgical and especially minimally-invasive surgical hemostasis. However, quality of vessel sealing is only suboptimal and major coaptive desiccation parameters have yet to be investigated in depth. Moreover, the potentially hazardous capacity of electrosurgery to induce both post-operative adhesions and thermal complications such as tissue necrosis has not been looked into in detail hitherto. In order to (1) optimize bipolar vessel sealing, to (2) better understand the biothermomechanics of thermal fusion, to (3) analyze the relationship between electrocoagulation and adhesion formation and to (4) develop a human in-vivo in-situ model for quantifying electrosurgery-induced thermal tissue effects and thermal tissue damage, the following studies were conducted. It was found that in an isolated porcine renal artery model, self-regulating modulation of energy-based vessel coagulation achieved superior thermal fusion of vascular tissue than CPC. This promising novel technique should therefore be further analyzed to determine its in-vivo efficacy in long-term studies. Moreover it was ascertained that compressive pressure during coaptation determines the seal quality. Upper and lower pressure boundaries for safe coaptation exist for both arteries and veins. Vessel sealing by thermal conduction without electrical current effects is possible but represents a less effective method for coaptation. These findings have implications for the rational design of new electrosurgical instruments. With regards to the adhesiogenic potential of bipolar tissue desiccation, we conclude that superficial trauma limited mostly to the parietal peritoneum may be a neglible factor in adhesion formation in this model. This appears to be irrespective of the mode of trauma. However, additional trauma to the underlying tissues, either by deeper electrocoagulation or suturing, lead to significantly increased adhesion formation. These data also show that there is a spectrum of electrocoagulation trauma at the lower end of which there is little adhesion formation. Finally, the new purpose-designed in-vivo in-situ model allows standardized, reproducible, quantitative assessment of electrocoagulation-induced thermal effects and damage in human tissue. It will likely provide further insight into the underlying biothermomechanics and may prove useful in the development of safety guidelines for laparoscopic electrosurgery.

Bipolar vessel sealing and electrosurgery in general is pivotal in surgical and especially minimally-invasive surgical hemostasis. However, quality of vessel sealing is only suboptimal and major coaptive desiccation parameters have yet to be investigated in depth. Moreover, the potentially hazardous capacity of electrosurgery to induce both post-operative adhesions and thermal complications such as tissue necrosis has not been looked into in detail hitherto. In order to (1) optimize bipolar vessel sealing, to (2) better understand the biothermomechanics of thermal fusion, to (3) analyze the relationship between electrocoagulation and adhesion formation and to (4) develop a human in-vivo in-situ model for quantifying electrosurgery-induced thermal tissue effects and thermal tissue damage, the following studies were conducted. It was found that in an isolated porcine renal artery model, self-regulating modulation of energy-based vessel coagulation achieved superior thermal fusion of vascular tissue than CPC. This promising novel technique should therefore be further analyzed to determine its in-vivo efficacy in long-term studies. Moreover it was ascertained that compressive pressure during coaptation determines the seal quality. Upper and lower pressure boundaries for safe coaptation exist for both arteries and veins. Vessel sealing by thermal conduction without electrical current effects is possible but represents a less effective method for coaptation. These findings have implications for the rational design of new electrosurgical instruments. With regards to the adhesiogenic potential of bipolar tissue desiccation, we conclude that superficial trauma limited mostly to the parietal peritoneum may be a neglible factor in adhesion formation in this model. This appears to be irrespective of the mode of trauma. However, additional trauma to the underlying tissues, either by deeper electrocoagulation or suturing, lead to significantly increased adhesion formation. These data also show that there is a spectrum of electrocoagulation trauma at the lower end of which there is little adhesion formation. Finally, the new purpose-designed in-vivo in-situ model allows standardized, reproducible, quantitative assessment of electrocoagulation-induced thermal effects and damage in human tissue. It will likely provide further insight into the underlying biothermomechanics and may prove useful in the development of safety guidelines for laparoscopic electrosurgery.