By means of two electrical connections called “electrodes”.
In “monopolar” electrosurgery, one is an “active” electrode and is used to introduce therapeutic current into tissue. These are also called “tips” or “electrode tips” and come in a wide variety of sizes and shapes suited to specific clinical indications for incision, excision, curettage, and coagulation. These are held in an insulated hand piece. The other electrode is the “dispersive” electrode and is in the form of a large flexible pad. The “Dispersive” connection to the patient is by means of capacitive coupling which can work through the patient’s coat without direct skin contact so that the patient reclines against the dispersive pad (or “plate”) completing the electrical circuit.
In “bipolar” electrosurgery, both electrodes are the same or similar size and are mounted on a common hand piece. No separate dispersive plate or pad is used and the cable from the bipolar hand piece to the electrosurgery unit has two conductors.
“Bipolar” refers to two things, a situation which engenders some confusion. First, it refers to a technique where therapeutic current is restrained to the immediate volume of tissue being treated and does not diffuse through the body. Bipolar electrodes are exemplified by bipolar forceps, where the two tips of the forceps are insulated from each other, and two wires connect the forceps to the unit. Bipolar also refers to the electrosurgical unit itself in terms of RF isolation. “Bipolar” is defined as a greater degree of isolation than “isolated”. Delmarva HFR isolated units are rated safe for bipolar coagulation but not for incision or excision. Bipolar accessories are certainly not safe with ground referenced generators.
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