EXPERIMENTAL INVESTIGATION ON THE EFFECTS AND SAFETY OF A LASER COAGULATOR AND ITS APPLICATION TO CLINICAL CASES

Abstract

The potential of YAG laser coagulator (MediLas, MBB) for endoscopic control of bleeding was investigated experimentally using a flexible fiberoptic laser transmission system. The depth of penetration of the laser beam into tissues was also studied. Results: 1) The radiation to the normal gastric mucosa resulted in a grayish discoloration surrounded by a reddish halo and regional edema. An ulceration ensued, which healed within 3 to 4 weeks. 2) There was no penetration into the serosa even when the radiations were repeated eight times with a power output of 45w for 3 seconds each, or three times with 65W for 3 seconds. 3) An artificial gastric bleeding by repeated endoscopic biopsies could be coagulated within 7.4 seconds with 45w, or within 5.5 seconds with 60W. Neither 20W nor 30W was sufficient to attain coagulation. Our study may show that at least 45W will be necessary to stop bleeding. 4) Arterial bleedings were produced by a surgical removal of a small part of the gastric mucosa. The rate of bleeding was 6.1 ml/min on an average. These bleedings could be coagulated by laser radiation with 40W for 18.0 seconds or with 50W for 15.7 seconds as a mean. 5) A bleeding from a mesenteric artery as large as 1 mm in diameter could be coagulated by YAG-laser. The hemostatic efficiency was closely related to the blood volume and the velocity of the flow in the bleeding arteries. 6) A radiation with 45W for 3 seconds caused a photocoagulative effect to a depth of 5 mm in the liver, 5 mm in the kidney and 2 mm in the spleen.