Development of a gel dedicated to gel immersion endoscopy

Abstract

<b>Backgrounds and study aims </b> Gel immersion endoscopy is a novel technique to secure the visual field during endoscopy. The aim of this study was to develop a dedicated gel for this technique. <b>Methods </b> To identify appropriate viscoelasticity and electrical conductivity, various gels were examined. Based on these results, the dedicated gel "OPF-203" was developed. Efficacy and safety of OPF-203 were evaluated in a porcine model. <b>Results </b> <i>In vitro</i> experiments showed that a viscosity of 230 to 1900 mPa·s, loss tangent (tanδ) ≤ 0.6, and hardness of 240 to 540 N/cm ² were suitable. <i>Ex vivo</i> experiments showed electrical conductivity ≤ 220 μS/cm is appropriate. <i>In vivo</i> experiments using gastrointestinal bleeding showed that OPF-203 provided clear visualization compared to water. After electrocoagulation of gastric mucosa in OPF-203, severe coagulative necrosis was not observed in the muscularis but limited to the mucosa. <b>Conclusions </b> OPF-203 is useful for gel immersion endoscopy.