In electrosurgical procedures, the tissue is heated by an electric current. Although electrical devices that create a heated probe may be used for the cauterization of tissue in some applications, electrosurgery is usually used to refer to a quite different method than electrocautery. Electrocautery uses heat conduction from a probe heated to a glowing temperature by a direct current (much in the manner of a soldering iron). This may be accomplished by direct current from dry-cells in a penlight-type device.
Electrosurgery, by contrast, uses radio frequency (RF) alternating current to heat the tissue by RF induced intracellular oscillation of ionized molecules that result in an elevation of intracellular temperature. When the intracellular temperature reaches 60 degrees C, instantaneous cell death occurs. If tissue is heated to 60-99 degrees C, the simultaneous processes of tissue desiccation (dehydration) and protein coagulation occur. If the intracellular temperature rapidly reaches 100 degrees C, the intracellular contents undergo a liquid to gas conversion, massive volumetric expansion, and resulting explosive vaporization.
Appropriately applied with electrosurgical forceps, desiccation and coagulation result in the occlusion of blood vessels and halting of bleeding. While the process is technically a process of electrocoagulation, the term “electrocautery” is sometimes loosely, non technically and incorrectly used to describe it. The process of vaporization can be used to ablate tissue targets, or, by linear extension, used to transect or cut tissue. While the processes of vaporization/ cutting and desiccation/coagulation are best accomplished with relatively low voltage, continuous or near continuous waveforms, the process of fulguration is performed with relatively high voltage modulated waveforms. Fulguration is a superficial type of coagulation, typically created by arcing modulated high voltage current to tissue that is rapidly desiccated and coagulated. The continued application of current to this highly impedant tissue results in resistive heating and the achievement of very high temperatures – enough to cause breakdown of the organic molecules to sugars and even carbon, thus the dark textures from carbonization of tissue.