Zhenglong Sun

Robotic system for no-scar gastrointestinal surgery.

Flexible endoscopy allows diagnostic and therapeutic interventions on the gastrointestinal (GI) tract. Simple procedures can be performed endoscopically using currently available tools. More advanced endoscopic surgical interventions are much desired and anticipated, yet they await improvements in instrumentation.

Robot-Assisted Endoscopic Submucosal Dissection Is Effective in Treating Patients With Early-Stage Gastric Neoplasia

BACKGROUND & AIMS Endoscopic submucosal dissection (ESD) is a new technique for endoscopic resection of early-stage gastrointestinal cancers. Though ESD achieves high rate of en bloc resection, it is technically difficult to master. The development of a novel robotic endoscopic system that has 2 arms attached to an ordinary endoscope-Master and Slave Transluminal Endoscopic Robot (MASTER)-has improved the performance of complex endoluminal procedures. We evaluated the efficacy of MASTER-assisted ESD in treatment of patients with early-stage gastric neoplasia. METHODS We performed a multicenter prospective study of 5 patients with early-stage gastric neoplasia, limited to the mucosa. After markings and circumferential mucosal incision, all submucosal dissections were performed using the MASTER system. We measured baseline demographics, tumor characteristics, and perioperative and clinical outcomes. RESULTS All patients underwent successful MASTER-assisted ESD. The mean submucosal dissection time was 18.6 minutes (median, 16 minutes; range, 3-50 minutes). No perioperative complications were encountered. Three patients were discharged from the hospital within 12 hours and 2 on the third day after the procedures. Two patients were found to have intramucosal adenocarcinoma, 1 had high-grade dysplasia, 1 had low-grade dysplasia, and 1 had a hyperplastic polyp. The resection margins were clear of tumors in all 5 patients. No complications were observed at the 30-day follow-up examination. Follow-up endoscopic examinations revealed that none of the patients had residual or recurrent tumors. CONCLUSIONS A flexible endoscopy robotic system can be used to perform ESD and effectively treat patients with early gastric neoplasia.

Master and slave transluminal endoscopic robot (MASTER) for natural Orifice Transluminal Endoscopic Surgery (NOTES)

Although the flexible endoscopy has been widely used in the medical field for many years, there is still great potential in improving the endoscopists capability to perform therapeutic tasks. Tentatively, tools for the flexible endoscope have poor maneuverability and limited Degree Of Freedom (DOF). In this paper, we propose a surgical robotic system MASTER (Master And Slave Transluminal Endoscopic Robot). MASTER is a dexterous and flexible master-slave device which can be used in tandem with a conventional flexible endoscope. Using this robotic system, ESD (Endoscopic Submucosal Dissection) and NOTES (Natural Orifice Transluminal Endoscopic Surgery) have been conducted on in vivo and ex vivo animal trials with promising results.

Natural orifice transgastric endoscopic wedge hepatic resection in an experimental model using an intuitively controlled master and slave transluminal endoscopic robot (MASTER)

BackgroundThe lack of triangulation of standard endoscopic devices limits the degree of freedom for surgical maneuvers during natural orifice transluminal endoscopic surgery (NOTES). This study explored the feasibility of adapting an intuitively controlled master and slave transluminal endoscopic robot (MASTER) the authors developed to facilitate wedge hepatic resection in NOTES.MethodsThe MASTER consists of a master controller, a telesurgical workstation, and a slave manipulator that holds two end-effectors: a grasper, and a monopolar electrocautery hook. The master controller is attached to the wrist and fingers of the operator and connected to the manipulator by electrical and wire cables. Movements of the operator are detected and converted into control signals driving the slave manipulator via a tendon-sheath power transmission mechanism allowing nine degrees of freedom. Using this system, wedge hepatic resection was performed through the transgastric route on two female pigs under general anesthesia. Entry into the peritoneal cavity was via a 10-mm incision made on the anterior wall of the stomach by the electrocautery hook. Wedge hepatic resection was performed using the robotic grasper and hook. Hemostasis was achieved with the electrocautery hook. After the procedure, the resected liver tissue was retrieved through the mouth using the grasper.ResultsUsing the MASTER, transgastric wedge hepatic resection was successfully performed on two pigs with no laparoscopic assistance. The entire procedure took 9.4 min (range, 8.5–10.2 min), with 7.1 min (range, 6–8.2 min) spent on excision of the liver tissue. The robotics-controlled device was able to grasp, retract, and excise the liver specimen successfully in the desired plane.ConclusionThis study demonstrated for the first time that the MASTER could effectively mitigate the technical constraints normally encountered in NOTES procedures. With it, the triangulation of surgical tools and the manipulation of tissue became easy, and wedge hepatic resection could be accomplished successfully without the need for assistance using laparoscopic instruments.

Endoscopic submucosal dissection of gastric lesions by using a master and slave transluminal endoscopic robot: an animal survival study.

BACKGROUND AND STUDY AIMS The feasibility of performing endoscopic submucosal dissection (ESD) using the Master and Slave Transluminal Endoscopic Robot (MASTER), a robotics-enhanced surgical system, has been shown in our previous study. This study aimed to further explore, in an animal survival study, the 2-week outcome of using MASTER to perform ESD. PATIENTS AND METHODS In this prospective study, ESD was performed on five female pigs (weighing 32.4 - 36.8 kg) under general anesthesia using the MASTER. The animals were observed for 2 weeks before being humanely killed for necropsy examination. The main outcome measures were completeness of resection, procedure-related complications, and survival at 2 weeks. RESULTS The procedure was successfully completed in all five pigs. It took a mean of 21.8 minutes (range 6 - 39 minutes) to complete the ESD of each gastric lesion. All lesions were excised en bloc; the average dimension of the lesions was 77 mm (range 25 - 104 mm). One pig sustained a small intraoperative perforation which was identified and successfully clipped. After completion of the ESD procedures, all pigs survived well for 2 weeks. Necropsy was performed, with intraoperative gastroscopy identifying all the ESD sites as healed. Histopathologic examination showed all ESD sites had healed with partial epithelialization. Microbiological tests of the peritoneal fluid showed only microbes typically found in pigs. CONCLUSION Performing ESD with MASTER was feasible and safe in this 2-week animal survival study.

Design of a master and slave transluminal endoscopic robot for natural orifice transluminal endoscopic surgery

Abstract Natural orifice transluminal endoscopic surgery (NOTES) is an endoscopic surgical intervention technique for treatment within the intraperitoneal cavity, which utilizes natural orifices (i.e. mouth, vagina, anus, etc.) as the entry point. In line with minimally invasive surgery (MIS), NOTES aims to perform surgical procedures without skin incisions, thus eliminating unsightly scars. In this article, a master—slave robotic system is proposed to enable the endoscopist to perform demanding NOTES procedures, which are currently performed by surgeons in an opened or keyhole surgery setting. The robotic system consists of a master console and slave manipulators driven by tendon—sheath actuation. Force prediction at the slave end is also introduced in this article to provide force feedback to the surgeon. Using the developed robotic system, liver wedge resection has been conducted in animal trials with promising results.

Elongation Modeling and Compensation for the Flexible Tendon--Sheath System

In tendon-driven systems, the elongation of the tendon would result in inaccuracy in the position control of the system. This becomes a critical challenge for those applications, such as surgical robots, which require the tendon-sheath system with flexible and even time-varying configurations but lack of corresponding sensory feedback at the distal end due to spatial restrictions. In this paper, we endeavor to address this problem by modeling the tendon elongation in a flexible tendon-sheath system. Targeting at flexibility in practical scenarios, we first derived a model describing the relationship between the overall tendon elongation and the input tension with arbitrary route configurations. It is shown that changes in the route configuration would significantly affect the tendon elongation. We also proposed a remedy to enhance the system tolerance against potential unmodeled perturbations along the transmission route during operation. A scaling factor S was introduced as a design guideline to determine the scaling effect. A dedicated platform that was able to measure the tensions at both ends and the overall tendon elongation was designed and set up to validate the new findings. Discussions were made on the performance and the future implementation of the proposed models and remedy.

Haptic feedback and control of a flexible surgical endoscopic robot

A flexible endoscope could reach the potential surgical site via a single small incision on the patient or even through natural orifices, making it a very promising platform for surgical procedures. However, endoscopic surgery has strict spatial constraints on both tool-channel size and surgical site volume. It is therefore very challenging to deploy and control dexterous robotic instruments to conduct surgical procedures endoscopically. Pioneering endoscopic surgical robots have already been introduced, but the performance is limited by the flexible neck of the robot that passes through the endoscope tool channel. In this article we present a series of new developments to improve the performance of the robot: a force transmission model to address flexibility, elongation study for precise position control, and tissue property modeling for haptic feedback. Validation experiment results are presented for each sector. An integrated control architecture of the robot system is given in the end.

A Hybrid Field Model for Enhanced Magnetic Localization and Position Control

Most current magnetic localization and orientation systems use single magnetic dipole (MD) models to calculate magnetic field, which, due to the fundamental limitation of the dipole, becomes inaccurate near the source as the MD model is unable to compensate for geometry and physical imperfections. The novel approach undertaken here retains the parametric nature of the MD to model fields far from the source and simultaneously harnesses artificial neural networks (ANNs) to characterize the magnetic field close to the source with high accuracy. This hybrid ANN-MD (HAM) model segregates the space around the magnet along magnetic equipotential lines via the Levenberg-Marquardt algorithm, and a sigmoid function provides a smooth transition between the two regions. The HAM model was evaluated with experimental field data, and it yielded better performance than the other models. More specifically, for a solid axisymmetric permanent magnet, the HAM modeling error (RMSE) was on average over one order of magnitude smaller than that of the dipole-based model and two times smaller compared to the ANN-only model. Using model-based localization, tracking results from following a predetermined conical-helix path were promising, with an average error of 0.46 mm from only three sensor inputs. The HAM model was also tested in the closed-loop position control of a linear actuator, which was commanded to follow a sinusoid signal, and the root mean square error was 0.385 mm.

The future of transluminal surgery.

Continual innovations in surgical technologies are pushing the limits of what surgeons can achieve. No-scar surgery, a technique of performing intra-abdominal surgery by accessing through natural orifices to obviate abdominal incision, is becoming a future trend in minimally invasive surgery. As the technique of operation leaves the patient with no external scar, it is aesthetically more appealing than conventional surgery. Besides the minimally invasive nature of the operation, it could potentially eliminate the complications associated with conventional open surgery, reduce surgery-related morbidity and shorten recovery time. To date, numerous animal survival studies and limited human trials have shown that surgery performed through natural orifices is feasible and safe in highly skilled hands. We have previously demonstrated in pig models the feasibility of performing natural orifice transluminal endoscopic surgery (NOTES) using conventional endoscopic equipment and accessories [1–3]. In these studies, we successfully performed, on pigs, transgastric tubal ligation and oophorectomy, as well as transvaginal cholecystectomy using a standard endoscope and insulation-tipped diathermic knife, but it was not without technical constraints and safety concerns. Standard conventional endoscopic systems lacked the dexterity for intricate maneuvers within the confines of the peritoneal cavity. Owing to the lack of effective tools to properly close the transgastric opening after the operation, postoperative peritoneal infection could not be prevented. Three of the six animals operated on developed postoperative peritonitis, and were found to have peritoneal adhesions and abscesses on necropsy.