Backgound/Aims: One of the most important mechanical properties to consider in selecting clinically optimal stents would be expansile pressure. However, there were scanty data about the expansile pressure of stents. Furthermore, the data were improper for the clinical selection of stents. In this study, the authors tried to develop a precise and reproducible expansile pressure measurement method and to measure the expansile pressure of a variety of stent types. METHODS: We developed a new method of expansile force measurement using a cylindrical measurement device under a quasi-static equilibrium state and measured the expansile forces of six different stents made by various manufacturers; covered and uncovered Y2P SR , covered Y3E SR (Stentech, Korea), covered and uncovered Ultraflex and uncovered Wallstent (Boston Scientific, USA) RESULTS: Three important points critical in explaining and predicting the expansion characteristics of stents were found. Firstly, the radial expansion force varies greatly among the types of stents. Secondly, stents could be categorized to "soft stent" and "stiff stent" based upon the slope of expansion force change. Lastly, the initial force needed to compress the fully expanded stents is far greater in stents covered with membrane compared with the stents without membrane. CONCLUSIONS: The newly developed method of measurement helped the authors to get more realistic data of expansion force and pressure, which are thought to be helpful in clinical selection of stent type.
Esophagus ; Membranes ; Stents*

BACKGROUND/AIMS: Endoscopic assistive devices have been developed to reduce the complexity and improve the safety of surgeries involving the use of endoscopes. We developed an assistive robotic arm for endoscopic submucosal dissection (ESD) and evaluated its efficiency and safety in this in vitro pilot study. METHODS: ESD was performed using an auxiliary transluminal endoscopic robot. An in vitro test bed replicating the intra-abdominal environment and pig stomachs were used for the experiment. Participants were divided into skilled operators and unskilled operators. Each group performed ESD 10 times by using both conventional and robot-assisted methods. The perforation incidence, operation time, and resected mucous membrane size were measured. RESULTS: For the conventional method, significant differences were noted between skilled and unskilled operators regarding operation time (11.3 minutes vs 26.7 minutes) and perforation incidence (0/10 vs 6/10). Unskilled operators showed a large decrease in the perforation incidence with the robot-assisted method (conventional method vs robot-assisted method, 6/10 vs 1/10). However, the operation time did not differ between the conventional and robot-assisted methods. On the other hand, skilled operators did not show differences in the operation time and perforation incidence between the conventional and robot-assisted methods. Among both skilled and unskilled operators, the operation time decreased with the robot-assisted method as the experiment proceeded. CONCLUSIONS: The surgical safety of unskilled operators greatly improved with robotic assistance. Thus, our assistive robotic arm was beneficial for ESD. Our findings suggest that endoscopic assistive robots have positive effects on surgical safety.
Arm ; Endoscopes ; Endoscopy ; Hand ; In Vitro Techniques ; Incidence ; Methods ; Mucous Membrane ; Pilot Projects ; Self-Help Devices ; Stomach ; Surgery, Computer-Assisted

Background/Aims: Appropriate tissue tension and clear visibility of the dissection area using traction are essential for effective and safe endoscopic submucosal dissection (ESD). In this study, we developed a retractable robot-assisted traction device and evaluated its performance in colorectal ESD. Methods: An experienced endoscopist performed ESD 18 times on an ex vivo porcine colon using the robot and 18 times using the conventional method. The outcome measures were procedure time, dissection speed, procedure-related adverse events, and blind dissection rate. Results: Thirty-six colonic lesions were resected from ex vivo porcine colon samples. The total procedure time was significantly shorter in robot-assisted ESD (RESD) than in conventional ESD (CESD) (20.1±4.1 minutes vs 34.3±8.3 minutes, p<0.05). The submucosal dissection speed was significantly faster in the RESD group than in the CESD group (36.8±9.2 mm 2 /min vs 18.1±4.7 mm 2 /min, p<0.05). The blind dissection rate was also significantly lower in the RESD group (12.8%±3.4% vs 35.1%±3.9%, p<0.05). In an in vivo porcine feasibility study, the robotic device was attached to a colonoscope and successfully inserted into the proximal colon without damaging the colonic wall, and ESD was successfully performed. Conclusions The dissection speed and safety profile improved significantly with the retractable RESD. Thus, our robotic device has the potential to provide simple, effective, and safe multidirectional traction during colonic ESD.