Endoscope Shaft Research Articles

Viscosity Characteristics of Ideal Lubricants to Reduce Stress on Intestinal Mucosa During Balloon-Assisted Enteroscopy.

Balloon-assisted enteroscopy (BAE) is highly invasive and carries a higher risk of complications such as pain and perforation during enteroscope insertion. Applying lubricants to the small intestinal mucosa and reducing the dynamic friction coefficient (DFC) between the small intestinal mucosa and endoscopic shaft (ES) (or overtube (OT)) can minimize the invasiveness of BAE. However, the ideal viscosity characteristics of these lubricants remain unknown. In this study, a model is developed to measure the DFC using human small intestines from forensic autopsies and determine the ideal viscosity of low-friction lubricants that exhibit a minimal DFC, thus reducing the pressure on the intestinal lining during the procedure. The results reveal that the DFC is strongly correlated to the lubricant's viscosity rather than its chemical composition. Low-friction lubricants with viscosities within 0.20-0.32 and 0.35-0.58 Pa·s (at shear rates of 10 s-1) for the OT and ES, respectively, can significantly reduce the DFC, yielding optimal results. These findings highlight the role of viscosity in minimizing the friction between the equipment and small intestinal mucosa. The ideal low-friction lubricants satisfying the aforementioned viscosity ranges can minimize the invasiveness of BAE by decreasing the friction between the equipment and intestinal lining.

Identification of lubricant viscosity to minimize the frictional impact of colonoscopy on colonic mucosa

Applying a lubricant to the colonic mucosa and reducing the dynamic friction coefficient (DFC) between the endoscopic shaft and colonic mucosa may reduce colonoscopy invasiveness. However, the ideal lubricant viscosity remains unknown. Here, we developed a DFC measurement model integrating samples of colonic mucosa from forensic autopsy specimens into a simulated bowel bend and determined the low-friction lubricant viscosity that minimizes the DFC. Carboxymethyl cellulose, xanthan gum, hydroxyethyl cellulose, sodium alginate, and sodium polyacrylate aqueous solutions of various concentrations were used as lubricants. Low-friction lubricants minimized the load on the colonic mucosa during colonoscope insertion and reduced the total endoscopy insertion time. The highest correlation was between the DFC and the lubricant viscosity at a shear rate of 100 1/s. The lowest DFC was almost constant at approximately 0.09, irrespective of the chemical composition of the lubricant, and the low-friction lubricant viscosity (100 1/s) was 0.031–0.086 (median: 0.059). The viscosities of conventional colonoscopic lubricants were suitable for lubricating the anorectal skin owing to their low DFC, but too high for lubricating the colonic mucosa because of their high DFC. The utilization of the low-friction lubricants with the optimal viscosity can reduce the stress on colonic mucosa during colonoscopy.

PD45-12 COMPARISON OF INTRARENAL PRESSURE DURING RETROGRADE INTRARENAL SURGERY USING VARIOUS SINGLE-USE URETEROSCOPES: AN IN-VITRO STUDY

You have accessJournal of UrologyCME1 Apr 2023PD45-12 COMPARISON OF INTRARENAL PRESSURE DURING RETROGRADE INTRARENAL SURGERY USING VARIOUS SINGLE-USE URETEROSCOPES: AN IN-VITRO STUDY Shimpei Yamashita, Ryusuke Deguchi, Yuya Iwahashi, Masatoshi Higuchi, Takaaki Inoue, Yasuo Kohjimoto, and Isao Hara Shimpei YamashitaShimpei Yamashita More articles by this author , Ryusuke DeguchiRyusuke Deguchi More articles by this author , Yuya IwahashiYuya Iwahashi More articles by this author , Masatoshi HiguchiMasatoshi Higuchi More articles by this author , Takaaki InoueTakaaki Inoue More articles by this author , Yasuo KohjimotoYasuo Kohjimoto More articles by this author , and Isao HaraIsao Hara More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003358.12AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Various single-use ureteroscopes (su-URS) have been developed and become commercially available. The difference of scope size could lead to the difference of intrarenal pressure (IRP) during retrograde intrarenal surgery (RIRS). However, no previous study has directly compared IRP among different su-URS. The aim of this in-vitro study was to evaluate IRP during RIRS and compare those among various su-URS. METHODS: We created an artificial kidney model with a pressure sensor by using bladder evacuation device. The model was completely closed and the only back flow was on the side of the ureteroscope inside the ureteral access sheath (UAS) (Figure 1). We tested five su-URS (LithoVue, Wiscope, PU3022A, PU3033A and AXIS) with six different UAS (9.5/11.5Fr-14/16Fr). Using the automatic irrigation system, 30 seconds of irrigation was performed at various pressure (40-180mmHg) and steady state IRP was recorded. Six runs were tested per setting. We compared IRP among five su-URS. The diameter of endoscope tip and shaft were also measured and recorded. RESULTS: The diameter of endoscope tip was smallest in PU3033A, while the diameter of other endoscopes was almost similar. The diameter of endoscope shaft was largest in LithoVue, followed by PU3022A, AXIS, Wiscope and PU3033A. Measured IRP was different among su-URS, and endoscopes with larger shaft diameter tended to have higher IRP (Figure 2). Assuming that the cutoff value of IRP for the risk of postoperative sepsis was 30mmHg, the suitable size of UAS was considered to be 12/14Fr or more for LithoVue and PU3022A, 11/13Fr or more for AXIS and Wiscope and 10/12 Fr or more for PU3033A. CONCLUSIONS: Our results suggested that the size of endoscope shaft might affect IRP during RIRS, and IRP and suitable size of UAS could be different among various su-URS. Source of Funding: None. © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1167 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Shimpei Yamashita More articles by this author Ryusuke Deguchi More articles by this author Yuya Iwahashi More articles by this author Masatoshi Higuchi More articles by this author Takaaki Inoue More articles by this author Yasuo Kohjimoto More articles by this author Isao Hara More articles by this author Expand All Advertisement PDF downloadLoading ...

A Kinematic Modeling and Control Scheme for Different Robotic Endoscopes: A Rudimentary Research Prototype

In image-guided robotic surgery, there exist different endoscopes coupled either with specialized surgical robots (SSRs) or general industrial robots (GIRs). In general, SSRs mechanically respect the remote-center-of-motion (RCM) constraints with directly and explicitly controllable degrees-of-freedom (DoFs), whereas GIRs meet the constraints at the algorithmic level in an implicit manner, with a loss of direct control of some RCM DoFs. Conventionally, different robotic endoscopes are treated as different monolithic systems. Then, kinematic models and control schemes are separately established to automate different robotic endoscopes. This means that a similar analysis must be followed for each system, which is tedious and time-consuming. This letter introduces a modular method to analyze the individual kinematics of the robotic holder, the endoscope shaft and the surgical endoscope with RCM constraints explicitly handled. For achieving automation, the integrated kinematics of a generic robotic endoscope is determined by combining the kinematics of the modular elements. Considering that cameras are intrinsically embedded sensors, a visual servo control scheme applicable to different robotic endoscopes is formulated to incorporate four explicit (virtual) DoFs characterizing the RCM constraints in the control law. Simulations and experiments performed using three different robotic endoscopes validate the effectiveness and practicality of the kinematic modeling and control scheme for automatic field-of-view adjustment.

Control Evaluation of Antagonistic Series Elastic Actuation for a Robotic Endoscope Joint

Haptic feedback is typically missing during telemanipulation of surgical robots in minimally invasive surgeries, i.e., surgeons cannot feel the interaction forces between the instruments and tissues. Instead, surgeons have to solely rely on visual feedback, which increases complexity of guiding the instruments and poses the safety threat of unperceivable contacts outside the field of view. We propose a novel series elastic actuation design for articulated robotic endoscopes to overcome these limitations and evaluate an according device with one joint. Similar to the actuation of human fingers, the joint is driven by antagonistic tendons. Springs are integrated in the transmission between the tendons and the motors outside of the endoscope shaft. We estimated the joint angle and thereby the endoscope shape, measured spring deflection, estimated tendon forces from that deflection, and implemented force control for the endoscope joint. Zero torque control and impedance control were evaluated under application of both a continuous force and an impact force to the endoscope tip. The springs reduced impact forces at the tip of the endoscope through their inherent compliance. At the same time, feeding back the estimated force resulted in a stable tendon force control and a tunable endoscope joint control: Zero torque control effectively reduced the external forces, while the endoscope joint showed the expected stiffness in impedance control. These results show that antagonistic series elastic actuation is a promising concept for endoscope joint actuation and that it can lead towards safer robot–tissue interactions in surgical robotics.

Observing distant objects with a multimode fiber-based holographic endoscope

Holographic wavefront manipulation enables converting hair-thin multimode optical fibers into minimally invasive lensless imaging instruments conveying much higher information densities than conventional endoscopes. Their most prominent applications focus on accessing delicate environments, including deep brain compartments, and recording micrometer-scale resolution images of structures in close proximity to the distal end of the instrument. Here, we introduce an alternative “far-field” endoscope capable of imaging macroscopic objects across a large depth of field. The endoscope shaft with dimensions of 0.2 × 0.4 mm2 consists of two parallel optical fibers: one for illumination and the other for signal collection. The system is optimized for speed, power efficiency, and signal quality, taking into account specific features of light transport through step-index multimode fibers. The characteristics of imaging quality are studied at distances between 20 mm and 400 mm. As a proof-of-concept, we provide imaging inside the cavities of a sweet pepper commonly used as a phantom for biomedically relevant conditions. Furthermore, we test the performance on a functioning mechanical clock, thus verifying its applicability in dynamically changing environments. With the performance reaching the standard definition of video endoscopes, this work paves the way toward the exploitation of minimally invasive holographic micro-endoscopes in clinical and diagnostics applications.

Euclidean distances of laryngopharyngeal structures obtained from CT data for preclinical development of laryngoscopic devices.

This study aims to determine Euclidean distances between landmark structures in the larynx and pharynx to optimize endoscope shaft designs with regard to gentle and patient-oriented handling. Four Euclidean distances between landmarks in the larynx and pharynx were analyzed based on CT data of 66 patients. Distance (1): labium inferius oris-posterior pharyngeal wall at the cervical vertebra C1 (atlas), anterior edge of the tuberculum anterius atlantis. Distance (2): posterior pharyngeal wall adjacent to C1-entrance of pyriform sinus. Distance (3): inferior edge of the uvula-superior edge of the epiglottis. Distance (4): base of the vallecula-posterior pharyngeal wall. The minimum angular field of view α required to observe the glottis with a rigid transoral laryngoscope was derived trigonometrically from distances (2) and (4). Average Euclidean distances measured: Distance (1): 90.7mm ± 6.9mm in men and 86.9mm ± 5.9 mm in women. (2): 73.7mm ± 13.4mm and 56.2mm ± 7.6mm. (3): 25.2mm ± 8.6mm and 18.5mm ± 6.8mm. (4): 20.8mm ± 4.6mm and 16.5mm ± 3.4mm. α: 16.0° ± 3.9° and 16.6 ± 4.3°. As expected, statistically significant sex-related differences could be observed for distances (1)-(4). The results indicate that the length of transoral laryngoscopes should not be below 110mm and that a minimum angular field of view of α = 17° is required to fully observe the laryngeal inlet.

Innovations in surgical scopes—wireless steerable endoscopes and magnetic cameras

Conventional rod lens endoscope has for decades facilitated minimally invasive surgery (MIS) procedures. Video-assisted thoracic surgery (VATS) has continued to evolve in pursuit of minimizing surgical access trauma leading to the development of uniportal VATS. However, operating through a single small incision using the rod lens endoscope proves to be challenging. The view and maneuverability of the endoscope is limited by the unidirectional approach, and in addition a crowded port site increases risk of interference and fencing between instruments. These challenges have inspired innovation in endoscopic systems to allow wider range of viewing directions and angles with minimum scope movement. In particular, flexible endoscopes and magnetic endoscopes have unique advantages and potential over conventional rigid equipment. Flexible endoscopes with articulating tips offer distal dexterity, and provide wide range of viewing angles despite limited motion of endoscope shaft. Whereas magnetic anchored and actuated endoscopes go beyond tip dexterity, abandoning the rod body completely, and exploit magnetic linkage to navigate along intrathoracic surface, overcoming limit of unidirectional approach. Through wireless actuation, magnetic endoscopes also provide many views without occupying the access port, reducing incision size and risk of instrument interference. To apply the devices clinically, current prototypes still require lens cleaning strategy and sensors to match image quality of commercial systems. With these issues addressed, these novel systems may allow safer and more efficient performance of uniportal VATS, benefiting both surgeons and patients.

The Usefulness of Continuously Variable View Rigid Endoscope in Lacrimal Surgeries: First Intraoperative Experience.

The aims of this study were to illustrate the techniques and usefulness of a new rigid, variable-view endoscope in lacrimal surgeries. A 4-mm continuously variable view rigid endoscope (EndoCAMeleon) was used to assess 4 intraoperative scenarios in lacrimal surgeries. The endoscope offers variable views from 15° to 90° in one single plane while remaining shape invariant. Multiple planes were assessed after changing the direction of the endoscopic shaft. The ease of handling and optical performance was noted in each plane. Enhanced visualization over a wide angle range without moving the endoscope was found to be very beneficial intraoperatively. Accurate assessment of extent of cicatrization or synechiae causes of dacryocystorhinostomy failure, monitoring of internal common opening during trephination, and postoperative ostium evaluation was possible with wider and superior visualization. A complete endoscopic overview in one plane without the need of multiple angled endoscopes made the inspections detailed and less time consuming. Because the tip of the endoscope does not move, it was found to be effective in narrow working spaces without causing any collision with the tissues in the vicinity. Enhanced field of vision, quicker assessment, and ability to optimize visualization in a continuous mode are advantages of using a variable-view endoscope in lacrimal surgeries.

Robotic-assisted flexible colonoscopy: preliminary safety and efficiency in humans

The flexible endoscope is used as a platform for minimally invasive interventions. However, control of the conventional endoscope and multiple instruments is difficult. Robotic assistance could provide a solution and better control for a single operator. A novel platform should also enable interventions in areas that are currently difficult to reach. This study evaluates the safety and efficacy of a robotic platform that guides a conventional endoscope through the large bowel. Adult patients scheduled for routine diagnostic colonoscopy were included in this feasibility study. The endoscope was introduced using a robotic add-on to provide tip bending and air/water actuation. The endoscopist directly controlled the endoscope shaft. Upon cecal intubation, the add-on was detached and the procedure continued using conventional control. Primary evaluation parameters were the number of serious adverse events and the percentage of successful cecal intubations. The procedure was performed on 22 consecutive patients who all gave informed consent. There were no serious adverse events. Cecal intubation was successful in 15 patients (68%) using the robotic add-on. Six cases were completed after conversion to conventional control: 3 cases were converted to pass sharp angulation in the flexures and 3 cases were converted after technical difficulties. One case was not successful with either technique because of severe diverticulosis. The robotic add-on steering module allows safe endoscope intubation to reach intervention sites throughout the large bowel. The next step is to clinically evaluate complementary instrument and shaft-guiding modules in therapeutic procedures.

Magnetic Endoscopic Imaging: A Useful Ally in Colonoscopy

Magnetic endoscopic imaging (MEI) allows the configuration of the endoscope shaft to be visualised during colonoscopy. In particular, it allows the operator to confidentally recognise loop formation and subsequent loop resolution which is vital for colonoscope tip advancement and thus complete visualisation of the colon. Although generally accepted as a useful aid during colonoscopy, it is not universally available either due to cost or this facility is not available or compatible with all manufactured endoscopes. The data on its utility with regards colonoscopy performance outcome measures is mixed but overall likely to be beneficial. Its main value probably relates to colonoscopy training and its value may be realised with the large expansion in workforce required with the recent introduction of bowel cancer screening. Further work in this area is required. The manufacturer suggests some minor limitations in use because of potential interference with implanted electronic device, but its safety overall is well recognised.

A Novel Design for Steerable Instruments Based on Laser-Cut Nitinol

Omnidirectional articulated instruments enhance dexterity. In neurosurgery, for example, the simultaneous use of 2 instruments through the same endoscopic shaft remains a difficult feat. It is, however, very challenging to manufacture steerable instruments of the requisite small diameter. We present a new technique to produce such instruments by means of laser cutting. Only 3 coaxial tubes are used. The middle tube has a cutting pattern that allows the steering forces to be transmitted from the proximal to the distal end. In this way the steering part is concealed in the wall of the tube. Large diameter articulated instruments such as for laparoscopy might benefit from the excellent tip stability provided by the same economical technology. Coaxial nitinol tubes are laser-cut with a Rofin Stent Cutter in a specific pattern. The 3 tubes are assembled by sliding them over one another, forming a single composite tube. In a surgical simulator, the neurosurgical microinstruments and laparoscopic needle drivers were evaluated on surgical convenience. Simultaneous use of 2 neurosurgical instruments (1.5 mm diameter) through the same endoscopic shaft proved to be very intuitive. The tip of the steerable laparoscopic instruments (10 mm diameter) could resist a lateral force of more than 20 N. The angle of motion for either instrument was at least 70° in any direction. A new design for steerable endoscopic instruments is presented. It allows the construction in a range from microinstruments to 10-mm laparoscopic devices with excellent tip stability.

Rectal Retroflexion during Colonoscopy: A Bridge over Troubled Water

Rectal Retroflexion during Colonoscopy: A Bridge over Troubled Water

1552 DEVELOPMENT OF A NAVIGATION SYSTEM USING A MAGNETIC TRACKING SYSTEM FOR URETEROSCOPY

You have accessJournal of UrologyStone Disease: New Technology1 Apr 20131552 DEVELOPMENT OF A NAVIGATION SYSTEM USING A MAGNETIC TRACKING SYSTEM FOR URETEROSCOPY Kenji Yoshida, Gen Kawa, Hidefumi Kinoshita, and Tadashi Matsuda Kenji YoshidaKenji Yoshida Osaka, Japan More articles by this author , Gen KawaGen Kawa Osaka, Japan More articles by this author , Hidefumi KinoshitaHidefumi Kinoshita Osaka, Japan More articles by this author , and Tadashi MatsudaTadashi Matsuda Osaka, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.3062AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Current flexible ureteroscopes have smaller outer diameters and larger working channels. These improvements have allowed access to the entire intrarenal correcting system and also permitted urologists to efficiently treat upper urinary tract pathology. However, controlling a flexible ureteroscope require a certain level of expertise and it takes a lot of times and efforts to acquire the adequate skills. Novice operators sometimes lose the spatial orientation during examination in patients with complicated pyelocaliceal shapes. Therefore the perioperative navigation system would be useful for ureteroscopic treatment in upper urinary tract. In this study, we introduced our experimental model of ureteroscopic navigation system. METHODS Our navigation system uses a magnetic tracking system to detect the position of the sensor cord tip. Magnetic field generator detects the position and orientation of sensors within a defined dome-shaped volume. Cord with sensors passes through the endoscopic channel and position of tip and 8 cm from the tip were tracked in real time. The phantom model and 3-D images of the pyelocaliceal system were created from DICOM CT data obtained from a specific patient. The plaster phantom had an inner cavity to allow use of an endoscope and was fixed to an acrylic board in the magnetic field. The instrument tip position in the magnetic field was detected by calibration. To align the position of the pyelocaliceal phantom to 3D images, the corner of the acrylic board was adjusted using fiducial landmarks. RESULTS When passing an endoscope into the phantom, the tip position was displayed in 3D images. 3D images were displayed on the secondary monitor positioned next to the main monitor. Our navigation system accurately displayed the position of the ureteroscope in 3D images of the inside of the phantom (Figure). CONCLUSIONS Our navigation system could help to access to all calices of collecting system. It would increase the efficiency of stone removal and the chances of finding upper tract urothelial lesions. This system can also be used as a training system for novice endoscopists to acquire fundamental skills and has a possibility to reduce fluoroscopy time. To use our system clinically, the sensor must be built into the endoscope shaft and this is an area of future research. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e637 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Kenji Yoshida Osaka, Japan More articles by this author Gen Kawa Osaka, Japan More articles by this author Hidefumi Kinoshita Osaka, Japan More articles by this author Tadashi Matsuda Osaka, Japan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

An integrated approach to endoscopic instrument tracking for augmented reality applications in surgical simulation training

Despite the popular use of virtual and physical reality simulators in laparoscopic training, the educational potential of augmented reality (AR) has not received much attention. A major challenge is the robust tracking and three-dimensional (3D) pose estimation of the endoscopic instrument, which are essential for achieving interaction with the virtual world and for realistic rendering when the virtual scene is occluded by the instrument. In this paper we propose a method that addresses these issues, based solely on visual information obtained from the endoscopic camera. Two different tracking algorithms are combined for estimating the 3D pose of the surgical instrument with respect to the camera. The first tracker creates an adaptive model of a colour strip attached to the distal part of the tool (close to the tip). The second algorithm tracks the endoscopic shaft, using a combined Hough-Kalman approach. The 3D pose is estimated with perspective geometry, using appropriate measurements extracted by the two trackers. The method has been validated on several complex image sequences for its tracking efficiency, pose estimation accuracy and applicability in AR-based training. Using a standard endoscopic camera, the absolute average error of the tip position was 2.5 mm for working distances commonly found in laparoscopic training. The average error of the instrument's angle with respect to the camera plane was approximately 2°. The results are also supplemented by video segments of laparoscopic training tasks performed in a physical and an AR environment. The experiments yielded promising results regarding the potential of applying AR technologies for laparoscopic skills training, based on a computer vision framework. The issue of occlusion handling was adequately addressed. The estimated trajectory of the instruments may also be used for surgical gesture interpretation and assessment.

A new variable-view rigid endoscope evaluated in advanced gynecologic laparoscopy: a pilot study

This pilot study aimed to evaluate the optical performance and clinical handling of a new variable-view rigid endoscope with angulation from 0 º to 120 º in gynecologic laparoscopic surgery. The EndoCAMeleon endoscope was assessed by experienced surgeons and assistants during a variety of advanced gynecologic laparoscopic procedures. After each procedure, both the surgeon and the assistant each completed questionnaires designed to assess the endoscope's ease of handling and optical performance. The endoscope was assessed during 21 advanced procedures. Questionnaire responses confirmed surgeon and assistant satisfaction with the mechanical handling and vision provided by the endoscope. In particular, the ability to vary the viewing angles enabled the surgeon to visualize the surgical site without moving the endoscope shaft. The new endoscope performed well in the hands of experienced surgeons and assistants undertaking advanced procedures. The variable-view rigid endoscope allows the use of visual ports during primary port entry and enhances vision. Further study is required to evaluate its performance in routine practice.

Scopes Too Flexible...and Too Stiff

The article investigates how the difficulties caused by the flexibility of the endoscope shaft could be solved and to provide a categorized overview of designs that potentially provide a solution. The following are discussed: paradoxical problem of flexible endoscopy; NOTES or hybrid endoscopy surgery; design challenges; shaft-guidance: guiding principles; virtual track guidance; physical track guidance; shaft-guidance: rigidity control; material stiffening; structural stiffening; and hybrid stiffening.

Incomplete and Low Quality Inspection of the Stomach During Upper Endoscopy

Purpose: Recent reports have shown a surprisingly low protective effect of colonoscopy against colorectal cancer. Upper endoscopy (UE) is the preferred technique to diagnose gastric cancers, but as for colonoscopy, UE is associated with a substantial miss rate for gastric cancers. Aim: To determine completeness and quality of inspection of the stomach during routine UE by measurement of the time of endoscope retroflexion in the stomach and quality of inspection of the peri-esophageal fundus. Methods: All endoscopies performed in 8 endoscopy rooms at Mayo Clinic Rochester were automatically captured as part of a prospective, periodic assessment of quality and stored as de-identified, digital video files during a random week in the fall of 2009. Endoscopists were aware of the existence of the capturing system. UE video files were selected and analyzed for (1) time spent on retroflexion of the endoscope in the stomach and (2) the quality of inspection of the peri-esophageal fundus. Retroflexion time was measured in seconds by recording the first and last video frames showing retroflexion and dividing the difference by the frame rate. Absence/presence of retroflexion was scored as 0 or 1. Retroflexed fundus and esophago-gastric junction inspection was scored for absence/presence of (1) clearness of image, (2) 360 degree view around endoscope shaft and (3) adequate close-up views; each was scored as 0 or 1. For overall quality all scores were combined and categorized as follows: 0=Not Done; 1=Very Poor, 2=Poor, 3=Fair, 4=Good. Results: 96 video files represented UEs; all were of excellent video quality. All files were completely de-identified; therefore the indication for UE was unknown, a potential weakness of the study. Retroflexion was not performed in 4 UEs (4.2%). When performed, retroflexion time ranged from 1 to 127 seconds; excluding 4 outliers with retroflexion times greater than 30 seconds, the mean retroflexion time was 11.7+6.9 (M+SD) seconds. Overall retroflexion quality was Very Poor for 28 (29.2%), Poor for 1 (1%), Fair for 18 (18.8%) and Good for 45 (46.9%). Linear regression of overall retroflexion quality and retroflexion time showed an association that was highly significant (p<0.0001), even after removal of the 4 outlier UEs with retroflexion times greater than 30 seconds. Conclusion: 1. There is a large variation in time and effort spent on retroflexed inspection of the peri-esophageal fundus of the stomach during UE. 2. Incomplete or low quality inspection of the stomach occurs in about a third of UEs. 3. Longer inspection times are associated with higher quality UEs. 4. New methods need to be implemented that guarantee a high quality UE at all times for all patients. Disclosure: Piet C. de Groen, Wallapak Tavanapong, JungHwan Oh, Johnny Wong - Stockholder/Ownership interest: EndoMetric.

Vacuum packed particles as flexible endoscope guides with controllable rigidity

In order to fully benefit from the functionalities of flexible endoscopes in surgery a simple shaft-guide that can be used to support the flexible endoscope shaft is required. Such a shaft-guide must be flexible during insertion into the human body and rigidified when properly positioned to support the flexible endoscope shaft. A shaft-guide called ‘Vacu-SL’ was designed, consisting of a foil tube, filled with particles, that is rigidified by creating a vacuum in its tube. It is expected that the bending stiffness of a loaded, rigidified Vacu-SL shaft-guide is significantly influenced by the shape, hardness and size of the filler particles used. The goal of this study was to find the relations between the filler particles’ size, shape and hardness and a rigidified Vacu-SL shaft-guide’s bending stiffness. Vacu-SL test models were made using polystyrene, acrylic glass, glass, steel, and corundum particles as spheres, pebbles and granulate, with average diameters between 0.16–1.7 mm. These test models were rigidified and then loaded in a tensile tester. The forces needed for 5 and 10 mm deflections of the rigidified test models were measured. The results show that particle size, shape and hardness all influence a rigidified Vacu-SL shaft-guide’s bending stiffness. Size and hardness showed an optimum and granules performed better than spheres. Although the maximally measured bending stiffness might be insufficient to enable proper guidance of flexible endoscope shafts, the results suggest several ways to successfully improve the Vacu-SL shaft-guide.

Endoscopic Management of Cranial Arachnoid Cysts Using Extra-Channel Method

Arachnoid cysts (ACs) can be cured by making the definite and wide communication between the cyst and arachnoid space using endoscopy, but often it is impossible only through the usual working-channel (intra-channel) procedures. We discuss and propose a more valuable endoscopic technique with the presentation of our series of cases. We treated 9 patients with cortical AC in various locations with extra-channel endoscopic techniques. The patients ranged in age from 3 years to 60 years (mean age, 37.2 yrs). The follow-up period ranged from 12 to 26 months (mean follow-up duration, 17.2 months). All patients had large AC compressing the adjacent brain with clinical symptoms or signs. The authors performed extensive fenestration via single burr hole with the aid of endoscope. Being bypassed the rigid endoscope, through the space between the shaft of endoscope and guiding cannula (extra-channel method), fenestration procedures were done in the dry fields. Eight (88.9%) patients had been treated successfully with endoscope. One patient required shunt procedure. Among the eight patients who were treated with endoscopic procedure, 6 patients (66.7%) showed cyst reduction, and two (22.2%) showed disappearance of cyst. We suggest that extra-channel method will be simple and easy to perform using more valuable instruments with wider working area, and may promise better results compared to the conventional intra-channel endoscopic procedures.