Differentiation From Other Types of Electrosurgical Equipment
The hyfrecator differs from other electrosurgical devices primarily in being low-powered that is not intended for cutting tissue, or for use in other than conscious patients. The reason is that the hyfrecator does not use a dispersive return pad or "patient plate." It thus either passes a very low-powered current between forceps tips (bipolar output), or else passes an A.C. current between a single pointed metal electrode probe and the patient, with only the patient's self-capacitance providing a current sink (this is equivalent to considering displacement current to be the return current).
In the latter mode, the patient must sit or lie on an insulated table, much as in the case with objects to be charged electrostatically with high-voltage D.C. (as from a Van de Graaff generator, for example). Stray ground paths between the patient and foreign conductors (such as a metal table leading somewhere to earth-ground) can offer another capacitative reservoir besides the patient, and burns out of the area of treatment may thus result, from current passing between patient and the earth-ground. For this reason, hyfrecation and all non-ground-pad electrosurgery is performed only on conscious patients, who would be aware of the burn and discomfort from an unwanted earth-ground path. (In types of electrosurgery which do employ a ground-pad, the ground-pad path serves as such a low resistance ground to the machine, that extraneous other ground paths become unimportant, and thus with proper precautions these methods can, and often are, used on anesthetized patients).
Because hyfrecation is always a relatively low-power modality, it can be used in some situations (such as very small nevus removal or skin tag removal) without local anaesthesia. In many other uses to destroy larger lesions, a local anesthetic injection or regional nerve block is used. The pain from hyfrecation is due to the burning of tissue, and the pain of electrical current is absent, due to the high (radio) frequency which does not directly cause discharge of nerves.
Although the hyfrecator is not used primarily to cut tissue, it may be used in a secondary capacity to control bleeding, after tissue is cut by a standard surgical scalpel, or else it may be used to partly destroy superficial tissue, that is then removed by the scraping action of a curette. These are done under local anesthesia. An example of such a combination procedure is the standard method of electrodesiccation and curettage used by dermatologists to destroy skin cancers.
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