Dennis L. Fowler

Construct validity for the LAPSIM laparoscopic surgical simulator.

BackgroundThe skills required for laparoscopic surgery are amenable to simulator-based training. Several computerized devices are now available. We hypothesized that the LAPSIM simulator can be shown to distinguish novice from experienced laparoscopic surgeons, thus establishing construct validity.MethodsWe tested residents of all levels and attending laparoscopic surgeons. The subjects were tested on eight software modules. Pass/fail (P/F), time (T), maximum level achieved (MLA), tissue damage (TD), motion, and error scores were compared using the t-test and analysis of variance.ResultsA total of 54 subjects were tested. The most significant difference was found when we compared the most (seven attending surgeons) and least experienced (10 interns) subjects. Grasping showed significance at P/F and MLA (p < 0.03). Clip applying was significant for P/F, MLA, motion, and errors (p < 0.02). Laparoscopic suturing was significant for P/F, MLA, T, TD, as was knot error (p < 0.05). This finding held for novice, intermediate, and expert subjects (p < 0.05) and for suturing time between attending surgeons and residents (postgraduate year [PGY] 1-4) (p < 0.05).ConclusionsLAPSIM has construct validity to distinguish between expert and novice laparoscopists. Suture simulation can be used to discriminate between individuals at different levels of residency and expert surgeons.

Transvaginal natural orifice translumenal endoscopic surgery cholecystectomy: early evolution of the technique.

Introduction:Initial excitement for Natural Orifice Transluminal Endoscopic Surgery (NOTES) has been partly tempered by the reality that a NOTES procedure without laparoscopic or needleoscopic-assistance has not been performed by most groups. After safely performing laparoscopically-assisted transvaginal cholecystectomy in an IACUC-approved porcine model, we embarked on an IRB-approved protocol to ultimately perform a pure NOTES cholecystectomy. Materials and Methods:We describe our experience with performing a true NOTES tansvaginal cholecystectomy after safely accomplishing 3 laparoscopically-assisted hybrid NOTES procedures in humans. To overcome the retracting limitations of currently available endoscopes, we used a 5-mm curved or articulating retractor that was placed into the abdomen via a separate colpotomy in the second and third patient. In a fourth patient, pneumoperitoneum to 15 torr was obtained via a transvaginal trocar placed through a colpotomy made under direct vision and endoscopically placed clips were used for both the cystic duct and artery, thus, obviating the need for any transabdominally placed instruments or needles. Results:This patient was the first patient to undergo a completely NOTES cholecystectomy at our institution and to our knowledge in the United States. She was discharged on the day of surgery and has not suffered any complication after 1 month of follow-up. Conclusion:Pure NOTES transvaginal cholecystectomy without aid of laparoscopic or needleoscopic instruments is feasible and safe in humans. Additional experience with this technique will be required before comparative studies to standard laparoscopy and hybrid techniques are appropriate.

Design, simulation and evaluation of kinematic alternatives for Insertable Robotic Effectors Platforms in Single Port Access Surgery

This paper presents the task specifications for designing a novel Insertable Robotic Effectors Platform (IREP) with integrated stereo vision and surgical intervention tools for Single Port Access Surgery (SPAS). This design provides a compact deployable mechanical architecture that may be inserted through a single Ø15 mm access port. Dexterous surgical intervention and stereo vision are achieved via the use of two snake-like continuum robots and two controllable CCD cameras. Simulations and dexterity evaluation of our proposed design are compared to several design alternatives with different kinematic arrangements. Results of these simulations show that dexterity is improved by using an independent revolute joint at the tip of a continuum robot instead of achieving distal rotation by transmission of rotation about the backbone of the continuum robot. Further, it is shown that designs with two robotic continuum robots as surgical arms have diminished dexterity if the bases of these arms are close to each other. This result justifies our design and points to ways of improving the performance of existing designs that use continuum robots as surgical arms.

Design and Coordination Kinematics of an Insertable Robotic Effectors Platform for Single-Port Access Surgery

Single port access surgery (SPAS) presents surgeons with added challenges that require new surgical tools and surgical assistance systems with unique capabilities. To address these challenges, we designed and constructed a new insertable robotic end-effectors platform (IREP) for SPAS. The IREP can be inserted through a Ø15 mm trocar into the abdomen and it uses 21 actuated joints for controlling two dexterous arms and a stereo-vision module. Each dexterous arm has a hybrid mechanical architecture comprised of a two-segment continuum robot, a parallelogram mechanism for improved dual-arm triangulation, and a distal wrist for improved dexterity during suturing. The IREP is unique because of the combination of continuum arms with active and passive segments with rigid parallel kinematics mechanisms. This paper presents the clinical motivation, design considerations, kinematics, statics, and mechanical design of the IREP. The kinematics of coordination between the parallelogram mechanisms and the continuum arms is presented using the pseudo-rigid-body model of the beam representing the passive segment of each snake arm. Kinematic and static simulations and preliminary experiment results are presented in support of our design choices.

Integration and preliminary evaluation of an Insertable Robotic Effectors Platform for Single Port Access Surgery

In this paper, we present the integration and preliminary evaluation of a novel Insertable Robotic Effectors Platform (IREP) for Single Port Access Surgery (SPAS). The unique design of the IREP includes planar parallel mechanisms, continuum snake-like arms, wire-actuated wrists, and passive flexible components. While this design has advantages, it presents challenges in terms of modeling, control, and telemanipulation. The complete master-slave resolved-rates telemanipulation framework of the IREP along with its actuation compensation is presented. Experimental evaluation of the capabilities of this new surgical system include bi-manual exchange of rings, pick-and-place tasks, suture passing and knot tying. Results show that the IREP meets the minimal workspace and dexterity requirements specified for laparoscopic surgery, it allows for dual-arm operations such as tool exchange and knot tying in confined spaces. Although it was possible to tie a surgeons knot with minimal training, suture passing was difficult due to the limited axial rotation of the distal wrists.

Validation of laparoscopic surgical skills training outside the operating room: a long road

BackgroundSurgical skills training outside the operating room is beneficial. The best methods have yet to be identified. The authors aimed to document the predictive validity of simulation training in three different studies.MethodsStudy 1 was a prospective, randomized, multicenter trial comparing performance in the operating room after training on a laparoscopic simulator and after no training. The Global Operative Assessment of Laparoscopic Skills (GOALS) was used to evaluate operative performance. Study 2 retrospectively reviewed the operative performance of junior residents before and after implementation of a laparoscopic skills training curriculum. Operative time was the variable used to determine resident improvement. Study 3 was a prospective, randomized trial evaluating intern operative performance of laparoscopic cholecystectomy in a porcine model before and after training on a simulator. Operative performance was assessed using GOALS.ResultsAll three studies failed to demonstrate predictive validity. With GOALS used as the assessment tool, no difference was found between trained and untrained residents in studies 1 and 3. In study 2, the trained group took significantly longer to complete a laparoscopic cholecystectomy than the untrained group.ConclusionsNo correlation was found between the three types of training outside the operating room, and no improved operative performance was observed. Possible explanations include too few subjects, training introduced too late in the learning curve, and training criteria that were too easy. Additionally, simulator training focuses on precision, which may actually increase task time. Awareness of these issues can improve the design of future studies.

Reliable Assessment of Laparoscopic Performance in the Operating Room Using Videotape Analysis

The Global Operative Assessment of Laparoscopic Skills (GOALS) is a valid assessment tool for objectively evaluating the technical performance of laparoscopic skills in surgery residents. We hypothesized that GOALS would reliably differentiate between an experienced (expert) and an inexperienced (novice) laparoscopic surgeon (construct validity) based on a blinded videotape review of a laparoscopic cholecystectomy procedure. Ten board-certified surgeons actively engaged in the practice and teaching of laparoscopy reviewed and evaluated the videotaped operative performance of one novice and one expert laparoscopic surgeon using GOALS. Each reviewer recorded a score for both the expert and the novice videotape reviews in each of the 5 domains in GOALS (depth perception, bimanual dexterity, efficiency, tissue handling, and overall competence). The scores for the expert and the novice were compared and statistically analyzed using single-factor analysis of variance (ANOVA). The expert scored significantly higher than the novice did in the domains of depth perception (p = .005), bimanual dexterity (p = .001), efficiency (p = .001), and overall competence ( p = .001). Interrater reliability for the reviewers of the novice tape was Cronbach alpha = .93 and the expert tape was Cronbach alpha = .87. There was no difference between the two for tissue handling. The Global Operative Assessment of Laparoscopic Skills is a valid, objective assessment tool for evaluating technical surgical performance when used to blindly evaluate an intraoperative videotape recording of a laparoscopic procedure.

Insertable stereoscopic 3D surgical imaging device with pan and tilt

In this paper, we present an insertable stereoscopic 3D imaging system for minimally invasive surgery. It has been designed and developed toward the goal of single port surgery. The device is fully inserted into the body cavity and affixed to the abdominal wall. It contains pan and tilt axes to move the camera under simple and intuitive joystick control. A polarization-based stereoscopic display is used to view the images in 3D. The camerapsilas mechanical design is based upon a single camera prototype we have previously built. We have run calibration tests on the camera and used it to track surgical tools in 3D in real-time. We have also used it in a number of live animal tests that included surgical procedures such as appendectomy, running the bowel, suturing, and nephrectomy. The experiments suggest that the device may be easier to use than a normal laparoscope since there is no special training needed for operators. The Pan/Tilt functions provide a large imaging volume that is not restricted by the fulcrum point of a standard laparoscope. Finally, the 3-D imaging system significantly improves the visualization and depth perception of the surgeon.

Injection sclerotherapy of esophageal varices using ethanolamine oleate

Fifty-three patients with upper gastrointestinal bleeding and proven esophageal varices were treated by intravascular injection sclerotherapy of the varices using a mixture of ethanolamine oleate, bovine thrombin and cephalothin. An intraesophageal balloon was used to impede craniad flow during the injection. Except in three patients who failed to stop bleeding from nonvariceal lesions, sclerotherapy was 94 percent successful in controlling bleeding. The mortality rate in sclerotherapy patients with ascites was 25 percent compared with 54 to 75% reported elsewhere. There has been no rebleeding from varices after the third treatment week in patients followed up for up to 14 months.

Insertable Surgical Imaging Device with Pan, Tilt, Zoom, and Lighting

In this paper we describe work we have done in developing an insertable surgical imaging device with multiple degrees of freedom for minimally invasive surgery. The device is fully insertable into the abdomen using standard 12 mm trocars. It consists of a modular camera and lens system which has pan and tilt capability provided by two small DC servo motors. It also has its own integrated lighting system that is part of the camera assembly. Once the camera is inserted into the abdomen, the insertion port is available for additional tooling, motivating the idea of single-port surgery. A third zoom axis has been designed for the camera as well, allowing close-up and far-away imaging of surgical sites with a single camera unit. In animal tests with the device we have performed surgical procedures including cholecystectomy, appendectomy, running (measuring) the bowel, suturing, and nephrectomy. Preliminary tests suggest that the new device may have advantages over a standard laparoscope including the following. • Low-cost and simple design. • Easier and more intuitive to use than a standard laparoscope. • Joystick operation requires no specialized operator training. • Pan/tilt functions provide a large imaging volume not restricted by the fulcrum point of standard laparoscope. • Time to perform procedures was better than or equivalent to a standard laparoscope. We believe these insertable platforms will be an integral part of future surgical systems. The platforms can be used with tooling as well as imaging devices, allowing many surgical procedures to be performed using such a system.