Friction behavior between endoscopy and esophageal internal surface

Abstract

During gastrointestinal endoscopy, endoscopy is pushed into human digestive tract with the aid of outside force, which may cause a series of complications due to repeatedly inserting, rotating, pushing and retrieving operation. These are serious friction damage problems that few studies have focused on. In this paper, the friction behavior between the front-tip of gastroscopy and esophageal wall tissue during endoscopy was studied by using a UMT-II Micro-Tribometer. Fresh porcine esophagus of different anatomical sites (thoracic, abdominal and cervical esophagus) and layers in vitro was chosen as the tissue samples. The normal force was from 0.2 to 1.0N, the sliding speed was from 0.1 to 0.9mm/s, and the unidirectional sliding displacement was 22mm to simulate the endoscopy manipulation. Results showed that the typical “stick-slip” phenomena appeared in the process of the front-tip sliding on the esophageal internal surface, which was related to the alternating deformation, recovery as well as the energy dissipation of esophageal tissue. The friction coefficient decreased with the increasing normal load and increased with the increasing sliding speed. Since the physiological structure and mechanical property of esophagus were diverse in different anatomical sites and layers, there would be a lower friction coefficient in the thoracic esophagus compared with the cervical and abdominal esophagus. Besides, the friction coefficient in intact esophagus was larger than that in layered esophagus. The results can provide the basic data for safety operation and damage control during gastrointestinal endoscopy.