[Non-contact argon gas coagulation in flexible endoscopy of the gastrointestinal tract: in vitro studies and initial clinical experiences].

Diathermocoagulation is indispensable in interventional endoscopy. The argon beam coagulation represents an innovative electrocoagulation method, where high-frequency alternating current is conducted to tissues by ionized argon gas without contact. Before clinical application we performed in vitro studies to evaluate depth and diameter of tissue coagulation of fresh resectations from stomach, small intestine and colon. Power and gas flow were graduated in five steps from 40 to 155 W and from 2 to 7 l/min respectively. Coagulation time (1 s-10 s) and angle of the probe in relation to tissue surface (45 degrees, 90 degrees) were varied. The maximal depth of necrosis was 2.4 mm, the maximal diameter 1.1 cm. There was no perforation found, even in critical areas like colon and duodenum. Accordingly argon beam coagulation was performed in 41 consecutive patients. The power and gas flow were varied in two stages between 40 and 75 watts and 2 and 3 l/min respectively. Coagulation time and angle of the probe were handled individually. In 32 of the 33 patients with bleeding from angiodysplastic lesions or polypectomy sites, with oozing of blood from erosions or ulcers or with bleeding due to vascular penetration by tumors definitive hemostasis was achieved in one to two sessions. In all of the four patients with residual sessile adenoma tissue complete removal was possible. Esophageal patency was restored in all four patients with stenosing tumors. In one patient with angiodysplasia of the cecal pole an asymptomatic accumulation of gas in the submucosa was observed which cleared spontaneously. In two patients with extensive esophageal carcinoma there was a transitory--also asymptomatic--accumulation of gas in the mediastinum and peritoneal cavity but no reference to perforation. The non-contact argon electrocoagulation is in gastrointestinal endoscopy an effective and non-expensive alternative to laser-technique.