Typically consisting of an electrical generator and one or multiple electrodes, an electrosurgical unit is often used in heating body tissues to prevent blood loss. The machine can be used in an operating room, or during an outpatient procedure. It is generally used to coagulate blood vessels, heat tissue, and cut, all using high-frequency electric current. Common electrosurgical procedures include dermatological, spinal, cardiac, and orthopedic surgeries; to prevent burns, a contact return pad, grounding pad, or conductive gel is typically used during the procedure. A return electrode monitoring system can also be used to shut the system down if the current becomes high enough to burn a patient.
The electrosurgical unit, first used in the 1920s, generally incorporates a main generator, electrode blades and needles, switches, and hand or foot controls. With a machine in bipolar configuration, a type of forceps is used to connect the two electrical poles of the generator to pass current through the tissue. Patients treated with a machine in monopolar configuration often lie on top of a metal plate or plastic pad that connects to the return electrode. Surgeons typically make contact with a single pointed probe to heat a localized area.
When operating at low power, an electrosurgical unit is sometimes used without a return electrode; the human body usually has the capacity to create a return path for the current. Electrosurgical devices can be used to cut, which is typically accomplished by vaporizing water and applying high voltage with a fine wire. Coagulation often requires less heat, and can also be performed by desiccation, during which even less heat is used to treat abnormalities under the skin. An electrode is usually activated in air just above the tissue during fulguration, which affects a relatively wider area on the surface of the skin.
The waveforms used by an electrosurgical unit can vary depending on the procedure. Energy can also be pulsed and the on and off time of the current is often adjustable as well. Most electrosurgical generators can operate at frequencies of 500 kilohertz to 3 megahertz, so proper use is important; otherwise burns can occur in parts of the body far from the site of the electrode.
An electrosurgical unit can be used at frequencies as low as 100 kilohertz. The stimulation of nerves and muscle is, therefore, usually lower and does not cause discomfort. Otherwise, muscle spasms, pain, and cardiac arrest can occur. When used properly, electrosurgical equipment typically makes operations safer and can minimize the complications that occur with uncontrolled bleeding.