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Electrosurgery is the application of a high-frequency electric current to biological tissue as a means to cut, coagulate, desiccate, or fulgurate tissue.〔Hainer BL, "Fundamentals of electrosurgery", ''Journal of the American Board of Family Practice'', 4(6):419-26, 1991 Nov-Dec. 〕〔(Electrosurgery for the Skin ), Barry L. Hainer M.D., Richard B. Usatine, M.D., ''American Family Physician'' (Journal of the American Academy of Family Physicians), 2002 Oct 1;66(7):1259-66.〕〔(A Simple Guide to the Hyfrecator 2000 ) Schuco International (London) Ltd.〕〔Boughton RS, Spencer SK, "Electrosurgical fundamentals", ''J Am Acad Dermatol'', 1987 Apr;16(4):862-7.〕〔Bouchier G, "The fundamentals of electro-surgery. High frequency current generators", ''Cah Prothese'', 1980 Jan;8(29):95-106. In French.〕〔Oringer MJ, "Fundamentals of electrosurgery", ''J Oral Surg Anesth Hosp Dent Serv'', 1960 Jan;18:39-49.〕〔Reidenbach HD, "Fundamentals of bipolar high-frequency surgery", ''Endosc Surg Allied Technol'', 1993 Apr;1(2):85-90.〕 (These terms are used in specific ways for this methodology—see below). Its benefits include the ability to make precise cuts with limited blood loss. Electrosurgical devices are frequently used during surgical operations helping to prevent blood loss in hospital operating rooms or in outpatient procedures.〔 In electrosurgical procedures, the tissue is heated by an electric current. Although electrical devices may be used for the cauterization of tissue in some applications, electrosurgery is usually used to refer to a quite different method than electrocautery. The latter 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 alternating current to directly heat the tissue itself. When this results in destruction of small blood vessels and halting of bleeding, it is technically a process of ''electrocoagulation,'' although "electrocautery" is sometimes loosely and nontechnically used to describe it. Often electrosurgery is mistakenly referred to as diathermy. Unlike Ohmic heating by electric current passing through the conductive tissue in conventional electrosurgery, diathermy means dielectric heating, produced by rotation of molecular dipoles in high frequency alternating electric field. This effect is most widely used in microwave ovens which operate at gigahertz frequencies. Electrosurgery is commonly used in dermatological, gynecological, cardiac, plastic, ocular, spine, ENT, maxillofacial, orthopedic, urological, neuro- and general surgical procedures as well as certain dental procedures. Electrosurgery is performed using an electrosurgical generator (also referred to as power supply or waveform generator) and a handpiece including one or several electrodes, sometimes referred to as an RF Knife. The apparatus when used for cutting or coagulation in surgery is called a "Bovie", after the inventor. == Electrical stimulation of neural and muscle cells == Neural and muscle cells are electrically-excitable, i.e. they can be stimulated by electric current. In human patients such stimulation may cause acute pain, muscle spasms, and even cardiac arrest. Sensitivity of the nerve and muscle cells to electric field is due to the voltage-gated ion channels present in their cell membranes. Stimulation threshold does not vary much at low frequencies (so called rheobase-constant level). However, the threshold starts increasing with decreasing duration of a pulse (or a cycle) when it drops below a characteristic minimum (so called chronaxie). Typically, chronaxie of neural cells is in the range of 0.1–10 ms, so the sensitivity to electrical stimulation (inverse of the stimulation threshold) decreases with increasing frequency in the kHz range and above. (Note that frequency of the alternating electric current is an inverse of the duration of a single cycle). To minimize the effects of muscle and neural stimulation, electrosurgical equipment typically operates in the radio frequency (RF) range of 100 kHz to 5 MHz. Operation at higher frequencies also helps minimizing the amount of hydrogen and oxygen generated by electrolysis of water. This is especially important consideration for applications in liquid medium in closed compartments, where generation of gas bubbles may interfere with the procedure. For example, bubbles produced during an operation inside an eye may obscure a field of view. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electrosurgery」の詳細全文を読む スポンサード リンク
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