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All surgeons should have a basic understanding of electrosurgical devices to allow for appropriate use of this equipment and to prevent unnecessary injury related to their use. Energy devices have their advantages and disadvantages for a given procedure, and it is up to the surgeon to understand the shortcomings of a particular device and decide which is the most appropriate for a given situation.

Electricity is the movement or flow of electrically charged particles from one electrode to another. Electrosurgery instruments apply an electrical current to tissue, enabling cutting, coagulating, desiccating, or fulgurating by generating heat. There are three properties of electricity that affect the rise in temperature of the tissue: Voltage, current, and resistance, or impedance. The interaction of these three properties is explained by Ohm's law, which describes the flow of electricity along a circuit:

Whereas current is a measure of electron movement through tissue in a given time, voltage is the driving force that moves the electrons against the tissue resistance or impedance within the circuit. Tissue resistance or impedance is a function of both the composition of the tissues and blood supply. As voltage drives electrons through the circuit against impedance, heat is generated. This tissue resistance or impedance produces heat rather than the active electrode. Therefore, tissues with greater impedance will result in the generation of more heat. Tissue impedance constantly changes as an electrical current is applied and the tissues become desiccated. The degree of heat leads to varying tissue effects (ssss1).