Argon plasma coagulation (APC) is a form of non-contact electrocautery. The technology was first used in the form of a "plasma scalpel" in 1971. Later, it was adapted for thoracoscopic and laparoscopic use. In 1991, specialized probes were created which allowed the use of APC in flexible endoscopy. The APC system consists of multiple components including a monopolar high-frequency electrosurgical generator, argon gas, gas flow meter, grounding pads, foot activation switch, and APC probes. During activation of the unit, there is simultaneous flow of argon gas from the probe and activation of the electrode resulting in ionization of the argon, creating a plasma field which is electrically conductive.1 Through the plasma, the electric current is passedto the tissue closest to the probe and with the least electrical resistance. The effect on the tissue is desiccation followed by coagulation and devitalization. As the tissue desiccates, electrical resistance increases and the argon beam moves to adjacent tissue, resulting in uniform application of energy to the tissue. Depth of effect is typically 2-3 mm, but is dependent on the power setting, duration of activation, and distance of the probe from the tissue.2 As power and activation time are increased, depth of penetration increases. As the distance from the probe to the tissue increases, depth is decreased. Using these factors, the depth of penetration can be controlled for treating superficial lesions in thin-walled structures such as the colon. In addition, tissues will have different thermal sensitivities. For instance, within the gastrointestinal tract the stomach and rectum are less sensitive while the right colon and duodenum are most sensitive. Excessive distension of the lumen with air orargon insufflation may also increase the thermal sensitivity of the tissue.
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