EFFECTS OF ND-YAG LASER ON CANINE GASTRIC MUCOSA UNDER VARIATION OF SUBMUCOSAL BLOOD FLOW

Abstract

Correlation between gastric submucosal blood flow and penetration depth into canine gstric wall by Nd-YAG laser radiation were studied using three mongrel dogs. The Nd-YAG Laser (Medialas ; M. B. B.) was fired through the biopsy channel of gastrofiberscope (GIF-D₃; Olympus) by an optical fiber with coaxial jet of CO₂ at the power of 30W, 50W, and 80W with exposure duration of 4 seconds. The gastric submucosal blood flow was measured using H₂ gas clearance method with a hydrogen elctrode which was stuck into the submucosal layer through the serosa at the middle body under lapalotomy. The gastric submucosal blood flow in three dogs showed variation from low value under 40ml / min. / 100g to high value over 70ml / min. / 100g. The lower value of submucosal blood flow showed the dog, the deeper was the mucosal damage in propotion to the exposure power. After the administration of betazole hydrochloribe (2mg / kg, i.v.), gastric submucosal blood flow increased. The higher is the ratio of increasing, the more shallow and localized was the histological damage. These data may suggest that the blood flow in gastric wall plays an important role form the viewpoint of efficacy and safety in the radiation of Nd-YAG laser since it has cooling effect against the mucosal damage by laser radiation.