Conventional Flexible Endoscope Research Articles

Semi-automatic Knob System for Assisting Flexible Endoscope Steering

In this paper, a semi-automatic knob system for assisting control of flexible endoscope is introduced. For conventional flexible endoscope, the torque to bend the bending part is increased proportionally to the curvature of the insertion tube. As the bending angle increases, the required torque is increased. This characteristic makes a surgeon tired. The proposed semi-automatic knob system consists of a knob controller, a power generation unit, and a bending part. The knob controller includes four FSR (force sensitive resistor) sensors to measure external force applied by the operator. The power generation unit generates the power depending on the signal level of FSR sensors. Using the semi-automatic knob system, a user can control the steering of the flexible endoscope with less power as compared to conventional flexible endoscope. The usefulness of the proposed system is verified through experiments.

A Novel Flexible Robotic Endoscope With Constrained Tendon-Driven Continuum Mechanism

This letter presents a novel flexible robotic endoscope with a constrained tendon-driven continuum mechanism (CTCM) which is targeted for bariatric surgery. The robotic endoscope is composed of a UR5 robot and a CTCM-based flexible endoscope. By introducing a constraint tube, both the angulation and the length of the flexible segment can be controlled, ensuring improved flexibility and dexterity. The kinematic modeling of the flexible robotic endoscope is conducted with the remote center of motion (RCM) constraints and physical limits of the robotic system considered. To automate the endoscope robot, image-based visual servoing technique is employed. The kinematics modeling results in a quadratic programming (QP) based control framework with the physical limits and RCM constraints of the robotic endoscope involved. Experimental validation is performed to verify the effectiveness and superiority of the CTCM-based flexible endoscope for bariatric surgery as compared with conventional rigid and flexible endoscopes.

Surgical Robot for Intraluminal Access: An Ex Vivo Feasibility Study.

Early-stage gastrointestinal cancer is often treated by endoscopic submucosal dissection (ESD) using a flexible endoscope. Compared with conventional percutaneous surgery, ESD is much less invasive and provides a high quality of life for the patient because it does not require a skin incision, and the organ is preserved. However, the operator must be highly skilled because ESD requires using a flexible endoscope with energy devices, which have limited degrees of freedom. To facilitate easier manipulation of these flexible devices, we developed a surgical robot comprising a flexible endoscope and two articulating instruments. The robotic system is based on a conventional flexible endoscope, and an extrapolated motor unit moves the endoscope in all its degrees of freedom. The instruments are thin enough to allow insertion of two instruments into the endoscope channel, and each instrument has a bending section that allows for up-down, right-left, and forward-backward motion. In this study, we performed an ex vivo feasibility evaluation using the proposed robotic system for ESD in a porcine stomach. The procedure was successfully performed by five novice operators without complications. Our findings demonstrated the feasibility of the proposed robotic system and, furthermore, suggest that even operators with limited experience can use this system to perform ESD.

Evaluation of a robotic arm-assisted endoscope to facilitate endoscopic submucosal dissection (with video)

Endoscopic submucosal dissection (ESD) is considered technically difficult and challenging using a conventional flexible endoscope, mainly due to the lack of proper countertraction to expose the submucosal dissection plane. This study aimed to evaluate the feasibility of a traction method using a dexterous robotic arm in exvivo gastric ESD. ESD was performed in a total of 45 procedures using a portable endoscopic tool handler (PETH) (n= 30) and using the conventional method (n= 15) at various locations in the stomach. For each procedure, the performance data were recorded, including the total procedure time (minutes), incision time (minutes), dissection speed (mm2/minute), and blind dissection rate (%), to enable a comparison of the 2 ESD methods. The total procedure time was significantly shorter with PETH-ESD than in conventional ESD (23 vs 36 minutes, P= .011). This result is mainly attributed to the dissection speed, which was significantly faster, by more than 2.5 times, using the PETH (122.3 ± 76.5 vs 47.5 ± 26.9mm2/minute, P< .001). The blind dissection rate was greatly decreased in PETH-ESD (0 vs 20%, P< .001). There was no significant difference in the incision time (6.1 ± 5.0 vs 5.5 ± 2.9 min, P= .612). The countertraction method using the PETH significantly improved the dissection speed and reduced blind dissection by enhancing direct visualization of the submucosal plane. With the advantages of multidirectional traction, fine tension control, and regrasping, this new device is expected to improve the performance of ESD and further facilitate advanced endoscopic procedures.

Novel Motorized Spiral Enteroscopy: First Clinical Case

A novel reusable endoscope (Olympus Corp.) with an integral motor was developed for rotating a disposable short spiral overtube mounted on the insertion tube portion. The drive motor located in the endoscope handle is activated via foot pedals and controls the direction and speed of rotation of a coupler located in the middle of the endoscope’s insertion tube. The rotation coupler is the only portion of the endoscope that rotates; the distal and proximal portions of the insertion tube do not rotate. Other than the presence of the drive motor and the rotation coupler, the endoscope design is the same as that of conventional flexible endoscopes. The single-use spiral assembly is comprised of corrugated tubing with an atraumatic plastic spiral bonded to its exterior. It relies on rotation of the spiral component to “pleat” or “unpleat” the bowel either on or off the insertion tube as the spiral thread rotates in a clockwise or counter-clockwise direction, respectively. The operator can monitor how much torque is being applied to the small bowel by observing the system’s “visual force gauge”. This display provides the operator with a visual indication of the direction of rotation and the force of rotation throughout the examination. The clinical case represents the first use of this device in humans. Enteroscopy was indicated for treatment of angiodysplasias in the jejunum identified by small bowel capsule endoscopy in a 48 year old patient with iron deficiency anaemia. The novel motorized enteroscope could be smoothly inserted approximately 250 cm distal of the ligament of Treitz within 20 minutes. The technique allowed controlled movement of the tip of the endoscope and it provided an excellent visualization of the intubated small bowel. An angiodysplasia was detected and treated with argon plasma coagulation. Careful removal of the endoscope with counter-clockwise rotation of the spiral revealed no iatrogenic mucosal trauma. No adverse events were registered.

Active Locomotive Intestinal Capsule Endoscope (ALICE) System: A Prospective Feasibility Study

Owing to the limitations of the conventional flexible endoscopes used in gastrointestinal diagnostic procedures, which cause discomfort and pain in patients, a wireless capsule endoscope has been developed and commercialized. Despite the many advantages of the wireless capsule endoscope, its restricted mobility has limited its use to diagnosis of the esophagus and small intestine only. Therefore, to extend the diagnostic range of the wireless capsule endoscope into the stomach and colon, additional mobility, such as 3-D locomotion, and steering of the capsule endoscope, is necessary. Previously, several researchers reported on the development of mobility mechanisms for the capsule endoscope, but they were unable to achieve adequate degrees of freedom or sufficiently diverse capsule motions. Therefore, we proposed a novel electromagnetic actuation system that can realize 3-D locomotion and steering within the digestive organs. The proposed active locomotion intestinal capsule endoscope (ALICE) consists of five pairs of solenoid components and a capsule endoscope with a permanent magnet. With the magnetic field generated by the solenoid components, the capsule endoscope can perform various movements necessary to the diagnosis of the gastrointestinal tract, such as propulsion in any direction, steering, and helical motion. From the results of a basic locomotion test, ALICE showed a propulsion angle error of less than 4° and a propulsion force of 70 mN. To further validate the feasibility of ALICE as a diagnostic tool, we executed ex vivo testing using small intestine extracted from a cow. Through the basic mobility test and the ex vivo test, we verified ALICE's usefulness as a medical capsule endoscopic system.

Ongoing Development and Directions in Flexible Robotic Endoscopy

The robotic system for flexible endoscopy was first developed as a platform enabling tissue triangulation in natural-orifice translumenal endoscopic surgery (NOTES). Then endoscopic submucosal dissection (ESD) was introduced and has widely been employed for the treatment of early gastrointestinal carcinoma. Subsequently, endoscopists became well aware of the limitations of their endoscopic manipulations with the conventional flexible endoscopes developed for diagnostic use, which led to the development of robotic systems for upper/lower gastrointestinal tract endoscopes intended for therapeutic use. Most flexible robotic endoscopes have 2 mechanical arms attached to the head, allowing surgeons to perform endoscopic manipulations, such as grasping, traction, incision, excision, and hemostasis. However, there are still many challenges that remain to be addressed: the ideal robotic endoscope has not yet been realized. This article reviews the ongoing developments and our own efforts in the area of flexible robotic endoscopy.

Double-AOTF-based aberration-free spectral imaging endoscopic system for biomedical applications

The problem of in vivo photoluminescence diagnostics of the tissues accessible by endoscopes is discussed. The spectral imaging module attachable to conventional rigid and flexible medical endoscopes is developed and described. It is based on a double acousto-optical tunable filter (AOTF) and a specialized optical coupling system. The module provides wide field of view (FOV), absence of image distortions, random spectral access, fast spectral image acquisition at any wavelength in the visible range and accurate measurement of reflectance spectrum in each pixel of the image. Images of typical biomedical samples are presented and discussed. Their spectra are compared to the reference data.

Single-handed controller reduces the workload of flexible endoscopy

The control of the conventional flexible endoscope is non-ergonomic and non-intuitive. A novel single-handed interface could reduce the experienced workload, without reducing current efficiency or effectiveness of endoscope manipulation. The aim of this study is to evaluate the workload, efficiency and effectiveness of a single-handed controller in colonoscopy, in comparison to a bimanual controller and the conventional angulation wheels. Twenty-one inexperienced students performed colonoscopies on a computer simulator using either the single-handed controller with a joystick interface, a bimanual controller with a joystick interface or the conventional angulation wheels. Participants performed three sessions of colonoscopies. After each session, the experienced workload was evaluated using a seven-component absolute scoring scale. Efficiency of the procedure was evaluated by the cecal intubation time and total-used scope length. Effectiveness was evaluated by the percentage of bowel wall visualization. The total workload of the single-handed controller was lower compared to the conventional angulation wheels for all three sessions. The total workload of the bimanual controller was lower compared to the conventional angulation wheels in the second and third session and also lower compared to the single-handed controller in the third session. There was no significant difference between the three control interfaces in time efficiency, used scope length or visualization performance. Single-handed and bimanual controllers with a joystick interface are a feasible approach to reduce the workload of colonoscopy without reducing efficiency or effectiveness of endoscope manipulation.

DragonFlex – Smart Steerable Laparoscopic Instrument

DragonFlex – Smart Steerable Laparoscopic Instrument

Towards automated visual flexible endoscope navigation

The design of flexible endoscopes has not changed significantly in the past 50years. A trend is observed towards a wider application of flexible endoscopes with an increasing role in complex intraluminal therapeutic procedures. The nonintuitive and nonergonomical steering mechanism now forms a barrier in the extension of flexible endoscope applications. Automating the navigation of endoscopes could be a solution for this problem. This paper summarizes the current state of the art in image-based navigation algorithms. The objectives are to find the most promising navigation system(s) to date and to indicate fields for further research. A systematic literature search was performed using three general search terms in two medical-technological literature databases. Papers were included according to the inclusion criteria. A total of 135 papers were analyzed. Ultimately, 26 were included. Navigation often is based on visual information, which means steering the endoscope using the images that the endoscope produces. Two main techniques are described: lumen centralization and visual odometry. Although the research results are promising, no successful, commercially available automated flexible endoscopy system exists to date. Automated systems that employ conventional flexible endoscopes show the most promising prospects in terms of cost and applicability. To produce such a system, the research focus should lie on finding low-cost mechatronics and technologically robust steering algorithms. Additional functionality and increased efficiency can be obtained through software development. The first priority is to find real-time, robust steering algorithms. These algorithms need to handle bubbles, motion blur, and other image artifacts without disrupting the steering process.

Place des nouvelles techniques endoscopiques pour l’évaluation de la dysplasie sur endobrachyoesophage : quel intérêt en pratique ?

Recent technological advances in optics, computer-aided analysis, and miniaturization have allowed for the development of virtual chromoendoscopy and confocal laser endomicroscopy (CLE). CLE is based on the use of either a confocal scanning microscope integrated into a conventional flexible endoscope (eCLE or endoscopebased CLE) or trans-endoscopic probes (pCLE or probebased CLE). Both virtual chromoendoscopic techniques and CLE have enabled endoscopists to better characterize the gastrointestinal mucosa during endoscopy, and it has stimulated significant interest in the application of these techniques in clinical gastroenterology. This review aims to evaluate the current data on the technical aspects and the utility of these new technologies in Barrett’s esophagus.

Compact AOTF-based spectral imaging system for medical endoscopic analysis

AbstractA prototype of a spectral imaging module is described which can be attached to conventional rigid and flexible medical endoscopes. It is based on acousto-optic tunable filters (AOTF) and provides fast spectral image registration at an arbitrary series of wavelengths. The main advantage of the device is the minimization of spatial and spectral image distortion by use of a specialized double AOTF monochromator. These properties ensure immediate and reliable detection of spectral features in any image pixel. Real-time spectral analysis, in addition to spectral visualization, provides the opportunity to make medical photoluminescence diagnostics more effective.

Feasibility of Transumbilical Flexible Endoscopic Preperitoneoscopy (FLEPP) and Its Utility for Inguinal Hernia Repair

Various NOTES (natural orifice translumenal endoscopic surgery) hernia repair techniques have been described. The aim of this study was to evaluate the feasibility of a transumibilically introduced conventional double-channel flexible endoscope for performing preperitoneoscopy (FLEPP, flexible endoscopic preperitoneoscopy technique) and to perform totally extraperitoneal (TEP) inguinal hernia meshplasty in an animal model. The study was done in 2 steps on 8 swines weighing 25 to 30 kg each: (1) establishing feasibility of preperitoneal dissection of the inguinal region using a conventional double-channel flexible gastroscope and making bed for mesh placement and (2) placement of a polypropylene mesh in the inguinal region to cover the myopectineal orifice. The flexible endoscope provided good vision and maneuverability to identify preperitoneal structures--namely, the arcuate line, insertion of rectus abdominis on pubis symphysis, inferior epigastric vessels, deep inguinal ring, spermatic cord, pubic symphysis, and psoas muscle--without causing any damage to any of the structures. The spermatic cord could be dissected to identify the vas deference. A 9 × 7 cm(2) oval mesh was successfully placed over the myopectineal orifice of Fruchaud with good overlap. Average time required for the complete FLEPP procedure (including mesh placement) was 55 minutes (range 45-90 minutes). This study demonstrates, for the first time, the feasibility of the transumbilical FLEPP technique and its utility for performing TEP inguinal hernia repair with prosthetic mesh placement in a swine model.

Robot-assisted transvaginal peritoneoscopy using confocal endomicroscopy: a feasibility study in a porcine model

Optical biopsy methods such as probe-based confocal laser endomicroscopy (pCLE) provide useful intraoperative real-time information, especially during minimally invasive surgery with flexible endoscopic or robotic platforms. By translating the probe at constant pressure across the target tissue, undistorted "mosaics" can be produced. However, this poses ergonomic challenges with a conventional flexible endoscope. A 100 μm confocal depth pCLE probe was integrated into a previously described seven degrees-of-freedom articulated endoscopic robot. After estimating the average workspace created by a female pneumoperitoneum, the accessibility of the peritoneal cavity by the device for robot-assisted pCLE peritoneoscopy was calculated. To demonstrate its in vivo feasibility, the robot was inserted transvaginally in a pig, under laparoscopic vision. Optical biopsy was performed of several targets within the peritoneal cavity. The workspace analysis calculated that 88 % of the surface of an estimated average female pneumoperitoneum could be contacted by the probe using the robot transvaginally. In vivo, the robot was manoeuvred to provide views of all abdominal and pelvic organs. At each target there was robotic acquisition of still pCLE images, and slowly translating images for the construction of increased field-of-view mosaics up to 2 mm in length. Optical biopsies took 1-2 min per target, and at 3.5 μm lateral resolution, the mosaic images showed characteristic features of anterior abdominal wall, liver, and spleen. In the porcine model, the robotically actuated method of performing peritoneoscopy and pCLE mosaicked optical biopsy is safe and provides a consistent means of acquiring near-histological grade images of submesothelial tissue. Clinical translation is likely to provide sufficient accessibility of the peritoneal cavity.

Establishment of a pure NOTES procedure using a conventional flexible endoscope

Mori et al. [1] discuss the possibility of using a conventional flexible endoscope during pure natural orifice transluminal endoscopic surgery (NOTES) in patients with gastric gastrointestinal stromal tumors (GISTs), which is a really amazing idea. They use several novel techniques during full-thickness resection of GISTs, which may lay the foundation for the realization of pure NOTES using only conventional flexible endoscopes. First, a nasal endoscope was introduced to either create a perforation or assist in pulling up the collapsed gastric wall to prevent the operative view from being obscured. Second, a duodenal balloon was used to prevent gas from flowing beyond the outlet of the stomach and causing uncomfortable distention of the intestine. Third, unlike previous studies, perforation was made at 10-mm intervals instead of a continuous incision, a process that can also provide landmarks for resection of GISTs.

Natural orifice translumenal endoscopic surgery (NOTES) navigation performance: a pilot study comparing surgeons and gastroenterologists

BACKGROUND: As an emerging surgical paradigm, NOTES is currently performed using conventional flexible endoscopes. Gastroenterologists are experts in handling this instrument; however, NOTES involves manipulation of the endoscope outside the lumen of the gastrointestinal tract. Surgeons are used to operating within the spatial environment of the peritoneal cavity. The aim of this study was to investigate whether either surgeons or gastroenterologists are superior at navigating the endoscope in a NOTES environment using the Imperial College Natural Orifice Simulated surgical Environment (NOSsE) as an assessment tool. METHODS: Nine novices, 5 gastroenterologists and 4 laparoscopic surgeons were recruited to navigate through a series of targets in the NOSsE phantom. End-points were time taken to complete the course and number of targets successfully visualised. RESULTS: Gastroenterologists and surgeons completed the course faster (p < 0.001) and revealed more targets than novices (p < 0.001). Overall, surgeons completed the course in less time than gastroenterologists (mean time 228 sec vs. 134 sec; p = 0.172) and visualised more targets (mean 8.83 vs. 7.53; p = 0.217) although neither reached statistical significance. CONCLUSIONS: The results of this pilot study suggest that surgeons are not disadvantaged when it comes to navigating an endoscope within a simulated NOTES environment compared to gastroenterologists. Therefore, as appears to be the current practice, it is acceptable for surgical teams to perform initial NOTES studies, provided they possess adequate skill, appropriate laboratory experience and ethical review board approval. With the evolution in surgical tools, we are likely to see improved instrumentation to aid in navigation in NOTES.

Establishment of pure NOTES procedure using a conventional flexible endoscope: review of six cases of gastric gastrointestinal stromal tumors

An increasing number of reports have recently been published on hybrid natural orifice transluminal endoscopic surgery (NOTES). These reports do not address how to complete an operation with a flexible endoscope alone (pure NOTES), but rather how to combine use of an endoscope and a laparoscope. Surgical procedures using flexible and rigid endoscopes have been developed using different processes and concepts. Recognizing this conceptual difference, we conducted a study to address how to establish a pure NOTES procedure. Six patients with gastric gastrointestinal stromal tumors (GISTs) underwent hybrid NOTES. Each case was retrospectively reviewed to determine the appropriateness of the treatment and the usefulness of the endoscopic submucosal dissection (ESD) method, double-scope method, spaced perforation method, duodenal balloon occlusion method, and loop clip technique. The development of operative procedures that take advantage of the characteristics of flexible endoscopes, even with conventional flexible endoscopic devices and conventional endoscopes alone, may contribute to the realization of pure NOTES.

Sp707 How to Successfully Manage Novel Technical Challenges in Per Oral Endoscopic Myotomy for Achalasia

Achalasia is a primary esophageal motility disorder and surgical disruption of the lower esophageal sphincter is usually performed, when conservative approaches failed to be sufficient. Since the first report of laparoscopic Heller myotomy in 1991, minimally invasive techniques have been increasingly used for definitive treatment of achalasia. Efforts in natural orifice translumenal surgery (NOTES) led to the development of novel methods such as submucosal endoscopic myotomy in an animal model. Recently, the clinical implementation of per oral endoscopic myotomy (POEM) was demonstrated. The clinical implementation of such novel procedures might conceal a novel variety of challenges, which have not been dealt with before. We describe the successful management of unexpected difficulties as well as lessons learned in an early clinical series of per oral endoscopic myotomies for the treatment of achalasia. We studied the initial five patients, enrolled in an institutional review board approved trial, who had per oral endoscopic myotomy for symptomatic achalasia. A conventional flexible endoscope with a transparent cap mounted onto the distal end was used. After mucosal incision and entry into the submucosal space, a tunnel within the esophageal wall was created using a blunt dissection or hook needle-knife cautery. The inner circular muscle fibers at the lower esophageal sphincter were then divided at a length of approximately 7 cm. The mucosal incision was then closed using hemostatic clips. All interventions were videotaped and analyzed on unexpected technical difficulties as well as their management were analyzed. POEM could be successfully performed in all patients (5/5) and resulted in immediate smooth passage of the endoscope through the gastro-esophageal sphincter. Although no clinical complications were observed, novel intra-operative technical challenges were observed. The transparent cap used on the endoscope loosened three times during retrograde movements and was subsequently lost within the submucosal tunnel. Several attempts to remove the submucosal foreign body with graspers or an endoscopic net failed as the cap twisted and was caught underneath the mucosa. With the aid of a balloon catheter the lost cap was finally lined-up with the endoscope and could be safely removed without injuring the esophageal mucosa. POEM appears to be an appealing therapeutic approach for achalasia and the knowledge of basic rescue maneuvers in case of technical challenges might be essential to shorten the learning curve of endoscopists and ensure patient's safety.

Confocal laser endomicroscopy in the “in vivo” histologicaldiagnosis of the gastrointestinal tract

Recent technological advances in miniaturization have allowed for a confocal scanning microscope to be integrated into a conventional flexible endoscope, or into trans-endoscopic probes, a technique now known as confocal endomicroscopy or confocal laser endomicroscopy. This newly-developed technology has enabled endoscopists to collect real-time in vivo histological images or "virtual biopsies" of the gastrointestinal mucosa during endoscopy, and has stimulated significant interest in the application of this technique in clinical gastroenterology. This review aims to evaluate the current data on the technical aspects and the utility of this new technology in clinical gastroenterology and its potential impact in the future, particularly in the screening or surveillance of gastrointestinal neoplasia.