A randomized comparison of laparoscopic, flexible endoscopic, and wired and wireless magnetic cameras on ex vivo and in vivo NOTES surgical performance.

BACKGROUND: The influence of endoscopic video camera (VC) image quality on surgical performance has not been studied. Flexible endoscopes are used as substitutes for laparoscopes in natural orifice translumenal endoscopic surgery (NOTES), but their optics are originally designed for intralumenal use. Manipulable wired or wireless independent VCs might offer advantages for NOTES but are still under development. OBJECTIVE: To measure the optical characteristics of 4 VC systems and to compare their impact on the performance of surgical suturing tasks. METHODS: VC systems included a laparoscope (Storz 10 mm), a flexible endoscope (Olympus GIF 160), and 2 prototype deployable cameras (magnetic anchoring and guidance system [MAGS] Camera and PillCam). In a randomized fashion, the 4 systems were evaluated regarding standardized optical characteristics and surgical manipulations of previously validated ex vivo (fundamentals of laparoscopic surgery model) and in vivo (live porcine Nissen model) tasks; objective metrics (time and errors/precision) and combined surgeon (n = 2) performance were recorded. RESULTS: Subtle differences were detected for color tests, and field of view was variable (65°-115°). Suitable resolution was detected up to 10 cm for the laparoscope and MAGS camera but only at closer distances for the endoscope and PillCam. Compared with the laparoscope, surgical suturing performances were modestly lower for the MAGS camera and significantly lower for the endoscope (ex vivo) and PillCam (ex vivo and in vivo). CONCLUSIONS: This study documented distinct differences in VC systems that may be used for NOTES in terms of both optical characteristics and surgical performance. Additional work is warranted to optimize cameras for NOTES. Deployable systems may be especially well suited for this purpose.

Magnetically anchored camera and percutaneous instruments maintain triangulation and improve cosmesis compared with single-site and conventional laparoscopic cholecystectomy.

BACKGROUND: This study evaluated operative outcomes and ergonomics for a magnetic camera (MAGS) used in conjunction with percutaneous instruments [percutaneous surgical set (PSS)] compared with single-site laparoscopic (SSL) and conventional laparoscopic (LAP) cholecystectomy techniques. METHODS: Four surgical trainees each performed three porcine cholecystectomies using three randomized techniques including MAGS/PSS, SSL, and LAP. The operative outcomes, procedure-specific ratings (1-5 scale; 1 = superior), workload (1-10 scale; 1 = superior), and global impressions (1-10 scale; 10 = superior) were recorded. Comparisons used analysis of variance (ANOVA) on ranks (Kruskal-Wallis), and p values lower than 0.05 were considered significant. RESULTS: The operative outcomes were similar except for significantly higher blood loss with SSL (16.3 ± 10.3) versus LAP (2.8 ± 1.5; p < 0.05) but not with MAGS/PSS (4.8 ± 3.8). Several inadvertent tissue-damaging events occurred with SSL but not with MAGS/PSS or LAP. The incision was significantly shorter with MAGS/PSS (29.3 ± 2.8 mm) and SSL (29.3 ± 2.5 mm) than with LAP (48.0 ± 3.6 mm; p < 0.05). Compared with SSL (3.6 ± 0.5), the procedure-specific ratings significantly favored MAGS/PSS (2.8 ± 0.4) and LAP (1.7 ± 0.2; p < 0.05). Ergonomics and technical challenges both were rated significantly inferior with SSL (4.3 ± 1.0 and 3.8 ± 0.5, respectively) versus LAP (1.5 ± 0.6 and 2.0 ± 0.8, respectively; p < 0.05) but not with MAGS/PSS (2.5 ± 1.0 and 3.0 ± 0.8, respectively). Both MAGS/PSS (4.5 ± 0.5) and SSL (4.8 ± 1.0) were associated with a significantly greater workload than LAP (2.5 ± 0.6; p < 0.05). Global impression ratings were significantly higher for LAP (8.7 ± 1.3) versus SSL (5.8 ± 2.0; p < 0.05) but not for MAGS/PSS (7.1 ± 1.8). Cosmesis was significantly better with MAGS/PSS (9.5 ± 0.6) versus LAP (6.5 ± 2.4; p < 0.05) but not with SSL (8.8 ± 1.3). CONCLUSION: The MAGS/PSS technique allows better triangulation and fewer technical difficulties than SSL and better cosmesis than LAP. Further development of these devices is warranted.

A randomized comparison of laparoscopic, magnetically anchored, and flexible endoscopic cameras in performance and workload between laparoscopic and single-incision surgery.

BACKGROUND: This study aimed to evaluate the surgeon performance and workload of a next-generation magnetically anchored camera compared with laparoscopic and flexible endoscopic imaging systems for laparoscopic and single-site laparoscopy (SSL) settings. METHODS: The cameras included a 5-mm 30° laparoscope (LAP), a magnetically anchored (MAGS) camera, and a flexible endoscope (ENDO). The three camera systems were evaluated using standardized optical characteristic tests. Each system was used in random order for visualization during performance of a standardized suturing task by four surgeons. Each participant performed three to five consecutive repetitions as a surgeon and also served as a camera driver for other surgeons. Ex vivo testing was conducted in a laparoscopic multiport and SSL layout using a box trainer. In vivo testing was performed only in the multiport configuration and used a previously validated live porcine Nissen model. RESULTS: Optical testing showed superior resolution for MAGS at 5 and 10 cm compared with LAP or ENDO. The field of view ranged from 39 to 99°. The depth of focus was almost three times greater for MAGS (6-270 mm) than for LAP (2-88 mm) or ENDO (1-93 mm). Both ex vivo and in vivo multiport combined surgeon performance was significantly better for LAP than for ENDO, but no significant differences were detected for MAGS. For multiport testing, workload ratings were significantly less ex vivo for LAP and MAGS than for ENDO and less in vivo for LAP than for MAGS or ENDO. For ex vivo SSL, no significant performance differences were detected, but camera drivers rated the workload significantly less for MAGS than for LAP or ENDO. CONCLUSION: The data suggest that the improved imaging element of the next-generation MAGS camera has optical and performance characteristics that meet or exceed those of the LAP or ENDO systems and that the MAGS camera may be especially useful for SSL. Further refinements of the MAGS camera are encouraged.

Maximizing coupling strength of magnetically anchored surgical instruments: how thick can we go?

BACKGROUND: The Magnetic Anchoring and Guidance System (MAGS) includes an external magnet that controls intra-abdominal surgical instruments via magnetic attraction forces. We have performed NOTES (Natural Orifice Transluminal Endoscopic Surgery) and LESS (Laparoendoscopic Single Site) procedures using MAGS instruments in porcine models with up to 2.5-cm-thick abdominal walls, but this distance may not be sufficient in some humans. The purpose of this study was to determine the maximal abdominal wall thickness for which the current MAGS platform is suitable. METHODS: Successive iterations of prototype instruments were developed; those evaluated in this study include external (134-583 g, 38-61 mm diameter) and internal (8-39 g, 10-22 mm diameter) components using various grades, diameters, thicknesses, and stacking/shielding/focusing configurations of permanent Neodymium-iron-boron (NdFeB) magnets. Nine configurations were tested for coupling strength across distances of 0.1-10 cm. The force-distance tests across an air medium were conducted at 0.5-mm increments using a robotic arm fitted with a force sensor. A minimum theoretical instrument drop-off (decoupling) threshold was defined as the separation distance at which force decreased below the weight of the heaviest internal component (39 g). RESULTS: Magnetic attraction forces decreased exponentially over distance. For the nine configurations tested, the average forces were 3,334 ± 1,239 gf at 0.1 cm, 158 ± 98 gf at 2.5 cm, and 8.7 ± 12 gf at 5 cm; the drop-off threshold was 3.64 ± 0.8 cm. The larger stacking configurations and magnets yielded up to a 592% increase in attraction force at 2.5 cm and extended the drop-off threshold distance by up to 107% over single-stack anchors. For the strongest configuration, coupling force ranged from 5,337 gf at 0.1 cm to 0 gf at 6.95 cm and yielded a drop-off threshold distance of 4.78 cm. CONCLUSIONS: This study suggests that the strongest configuration of currently available MAGS instruments is suitable for clinically relevant abdominal wall thicknesses. Further platform development and optimization are warranted.

Novel magnetically guided intra-abdominal camera to facilitate laparoendoscopic single-site surgery: initial human experience.

BACKGROUND: Magnetic anchoring guidance systems (MAGS) are composed of an internal surgical instrument controlled by an external handheld magnet and do not require a dedicated surgical port. Therefore, this system may help to reduce internal and external collision of instruments associated with laparoendoscopic single-site (LESS) surgery. Herein, we describe the initial clinical experience with a magnetically anchored camera system used during laparoscopic nephrectomy and appendectomy in two human patients. METHODS: Two separate cases were performed using a single-incision working port with the addition of a magnetically anchored camera that was controlled externally with a magnet. RESULTS: Surgery was successful in both cases. Nephrectomy was completed in 120 min with 150 ml estimated blood loss (EBL) and the patient was discharged home on postoperative day 2. Appendectomy was successfully completed in 55 min with EBL of 10 ml and the patient was discharged home the following morning. CONCLUSIONS: Use of a MAGS camera results in fewer instrument collisions, improves surgical working space, and provides an image comparable to that in standard laparoscopy.

Live video manipulator for endoscopy and natural orifice transluminal endoscopic surgery (with videos).

BACKGROUND: During fluoroscopy, radiologists and gastroenterologists are able to manipulate live fluoroscopic video for better orientation and visualization. During endoscopy and natural orifice transluminal endoscopic surgery (NOTES), this function is not currently available. Particularly during NOTES, the endoscopic image is sometimes inverted, and off-axis operation is required. OBJECTIVE: Our purpose was to develop and test a prototype live video manipulator (LVM) for endoscopy, laparoscopy, and NOTES. DESIGN: Prospective ex vivo and in vivo feasibility study. INTERVENTIONS: We developed a prototype LVM software for video image manipulation that can be easily installed on any computer. The video input is streamed into the computer and can be displayed on a standard monitor. LVM was tested ex vivo in the following functions: (1) instant live video rotation, (2) vertical or horizontal video inversion, (3) mirror imaging, and (4) digital zooming. These functions were also tested during upper and lower GI endoscopy, ERCP, diagnostic laparoscopy, and various transvaginal NOTES procedures (cholecystectomy, gastroenterostomy, and sleeve gastrectomy) in porcine models. MAIN OUTCOME MEASUREMENTS: Image quality observation between unmanipulated and manipulated live videos. RESULTS: LVM reliably and easily performed live video manipulation during these tests. Besides standard definition video signals, LVM is fully compatible with high-definition video endoscopy. Three observers reported that the subjective image quality was the same in specified areas between manipulated and unmanipulated live videos. LIMITATIONS: Observation and feasibility study. CONCLUSIONS: LVM reliably and conveniently performed live video manipulations. LVM requires minimal equipment, capital investment, and maintenance, and is easy to set up. LVM can be a useful tool in many medical imaging studies, including endoscopy, laparoscopy, and NOTES, either as a built-in technology or as an as-needed add-on feature.

Completely transvaginal NOTES cholecystectomy using magnetically anchored instruments.

INTRODUCTION: Natural orifice translumenal endoscopic surgery (NOTES) is an evolving field and suitable instruments are lacking. The purpose of this study was to perform transvaginal cholecystectomies using instruments incorporated into a magnetic anchoring and guidance system (MAGS). METHODS: Non-survival procedures were conducted in pigs (n = 4). Through a vaginotomy created under direct vision, a rigid access port was inserted into the peritoneal cavity and used to maintain a CO(2) pneumoperitoneum. MAGS instruments were deployed through the port and held in place on the peritoneal surface using magnetic coupling via an external handheld magnet which was optionally exchanged for an 18 ga percutaneous threaded needle anchor; instruments included a tissue retractor (a clip-fixated magnet or flexible graspers) and a cautery dissector. A gastroscope was used for visualization. RESULTS: The first two procedures ended prematurely due to instrumentation shortcomings and inadvertent magnetic coupling between instruments; one case required a laparoscopic rescue. Three new forms of instrumentation were developed: (1) a longer access port (50 cm) which provided easier deployment of instruments and suitable reach, (2) a more robust cauterizer with a longer, more rigid, pneumatically deployed tip with better reach and sufficient torque to allow blunt dissection, and (3) a more versatile tissue retractor with bidirectional dual flexible graspers which provided excellent cephalad fundus retraction and inferiolateral infundibulum retraction. With these modifications, 100% of the cholecystectomy was completed in the third and fourth animals using only a NOTES/MAGS approach. Retrieval of the tissue retractor resulted in a rectal injury in the third animal but further procedural modifications resulted in a successful procedure in the fourth animal with no complications. CONCLUSIONS: While still under development with more refinements needed, completely transvaginal cholecystectomy using MAGS instruments is feasible. By offering triangulation and rigidity, MAGS may facilitate a NOTES approach while alleviating shortcomings of a flexible platform.

Solo surgeon laparo-endoscopic single site nephrectomy facilitated by new generation magnetically anchored and guided systems camera.

INTRODUCTION: We report a redesigned magnetically anchored and guided systems (MAGS) camera with improved optics and a 30° downward viewing angle that facilitates solitary surgeon laparo-endoscopic single site (LESS) nephrectomy. METHODS: The prototype consists of an external 2 by 6 cm cylinder containing magnets positioned such that the intra-abdominal camera is anchored on the peritoneal surface with a default 30° downward angle. It was inserted through a 3 cm LESS-port periumbilical incision in three pigs (mean 47 kg). The camera was coupled with the handheld magnetic device across the anterior abdominal wall and was steered into position to view the kidney. LESS nephrectomy was then performed. RESULTS: Since a standard LESS laparoscope was not needed, only the two operative instruments were inserted through the single incision port, significantly decreasing instrument "clashing" compared with traditional LESS nephrectomy. Due to the favorable angle of view of the camera and its self-anchoring capability, no assistant was needed to drive the camera. Instead, the surgeon periodically made minor adjustments to optimize the view. The nephrectomy was completed without complication in an average of 35 minutes in these three nonsurvival animals. CONCLUSION: The MAGS camera provides good optics and easy maneuverability during LESS porcine nephrectomy. As with other MAGS instruments, by replacing a traditional transabdominal laparoscope that occupies access port space, use of this insertable camera may diminish some of the "collision challenge" of LESS surgery. Also, by being self-anchoring, this prototype may minimize the need for an assistant surgeon.

Magnetically anchored cautery dissector improves triangulation, depth perception, and workload during single-site laparoscopic cholecystectomy.

INTRODUCTION: This study evaluated operative outcomes and workload during single-site laparoscopy (SSL) using a magnetically anchored cautery dissector (MAGS) compared with a conventional laparoscopic hook cautery (LAP). METHODS: Each cautery was used to perform six SSL porcine cholecystectomies. For MAGS, the cautery device was inserted through the umbilical incision, magnetically coupled, and deployed; two graspers and a laparoscope were used. For LAP, two percutaneous retraction sutures, one grasper, a hook cautery dissector, and a laparoscope were used. Operative outcomes, surgeon ratings (scale, 1-5; 1 = superior), and workload (scale, 1-10; 1 = superior) were evaluated. RESULTS: No significant differences were detected for operative outcomes and surgeon ratings, however, trends were detected favoring MAGS. Surgeon workload ratings were significantly better for MAGS (2.6 ± 0.2) vs. LAP (5.6 ± 1.1; p < 0.05). For MAGS, depth perception and triangulation were excellent and the safe handling protocol was followed with no complications. For LAP, the parallelism of instruments and lack of triangulation hindered depth perception, caused instrument conflicts, and resulted in two minor complications (one superficial liver laceration and one inadvertent burn to the diaphragm). CONCLUSION: These data suggest that using the MAGS device for SSL cholecystectomy results in equivalent (or better) operative outcomes and less workload compared with LAP.

Magnetic anchoring and guidance system instrumentation for laparo-endoscopic single-site surgery/natural orifice transluminal endoscopic surgery: lack of histologic damage after prolonged magnetic coupling across the abdominal wall.

OBJECTIVES: To study the potential pathologic effect of prolonged compression of abdominal wall between the components. Magnetic Anchoring and Guidance System (MAGS) instruments ameliorate some of the challenges in triangulation created by laparo-endoscopic single-site and natural orifice translumenal endoscopic surgery. They consist of an intracorporeal magnetic device coupled to an external hand-held magnet used to anchor and "steer" it around the peritoneal cavity. METHODS: Three pigs (45.5-48.6 kg) underwent laparoscopic placement of magnetic devices in 4 quadrants, with the devices left in place for 2 or 4 hours. Full-thickness abdominal wall sections (mean 2.1 cm thick) where each MAGS platform was placed plus a control were harvested at 0, 2, or 14 days after surgery. Histologic assessment was then performed. RESULTS: Beyond mild blanching of the peritoneal surface with a few petechiae immediately after internal component removal, no gross tissue damage was seen. These changes were undetectable by 48 hours and no intra-abdominal adhesions were identified at necropsy. NADH stain for tissue viability in the 4 nonsurvival specimens showed no tissue damage. Hematoxylin and eosin stain showed no necrosis of either superficial or deep muscle, skin, or subcutaneous fat tissue in all 12 specimens when compared with the control. CONCLUSIONS: MAGS instruments do not appear to cause tissue damage or adverse clinical outcomes when coupled across thin porcine abdominal walls for up to 4 hours. Because the distance across the abdominal wall is generally greater in adult human beings, these findings support the further clinical development of magnetic instruments to be used in human patients.

Tissue compression analysis for magnetically anchored cautery dissector during single-site laparoscopic cholecystectomy.

INTRODUCTION: The purpose of this study was to evaluate the histological effects of dynamic abdominal wall compression using the magnetic anchoring and guidance system (MAGS) platform. METHODS: Cholecystectomy was performed in two nonsurvival and two survival pigs using a single-site laparoscopic (SSL) approach. A deployable MAGS cautery dissector was used to perform the entire dissection in conjunction with a laparoscope and other instruments. The abdominal wall areas corresponding to the region occupied by the MAGS platform were examined grossly and microscopically for signs of tissue damage. Gallbladder dissection time was 36 min with no complications. Compressed abdominal wall thickness was 1.4 cm. RESULTS: In all four animals, a very mild skin erythema was noted immediately postprocedure but was nonvisible within 20 min. Mild peritoneal blanching was noted in two animals, and one animal exhibited a 5-mm area of petechiae. Necropsy demonstrated no adhesions. Light microscopy documented no evidence of tissue injury for all specimens. DISCUSSION: This study demonstrated that the use of the MAGS cautery dissector for a SSL cholecystectomy was advantageous in providing triangulation and did not result in any significant gross or microscopic tissue damage despite the thin abdominal wall of the porcine model.

Complete transvaginal NOTES nephrectomy using magnetically anchored instrumentation.

BACKGROUND AND PURPOSE: Evolution of minimally invasive techniques has prompted interest in natural orifice transluminal endoscopic surgery (NOTES). Challenges for NOTES include loss of instrument rigidity, reduction in working envelopes, and collision of instrumentation. Magnetic anchoring and guidance system (MAGS) is one surgical innovation developed at our institution whereby instruments that are deployed intra-abdominally are maneuvered by the use of an external magnet. We present our initial animal experience with complete transvaginal NOTES nephrectomy using MAGS technology. MATERIALS AND METHODS: Transvaginal NOTES nephrectomy was performed in two female pigs through a vaginotomy, using a 40-cm dual-lumen rigid access port inserted into the peritoneal cavity. A MAGS camera and cauterizer were deployed through the port and manipulated across the peritoneal surface by way of magnetic coupling via an external magnet. A prototype 70-cm articulating laparoscopic grasper introduced through the vaginal access port facilitated dissection after deployment of the MAGS instruments. The renal artery and vein were stapled en-bloc using an extra-long articulating endovascular stapler. RESULTS: NOTES nephrectomies were successfully completed in both pigs without complications using MAGS instrumentation. The MAGS camera provided a conventional umbilical perspective of the kidney; the cauterizer, transvaginal grasper, and stapler preserved triangulation while avoiding instrument collisions. Operative duration for the two cases was 155 and 125 minutes, and blood loss was minimal. CONCLUSIONS: NOTES nephrectomy using MAGS instrumentation is feasible. We believe this approach improves shortcomings of previously reported NOTES nephrectomies in that triangulation, instrument fidelity, and visualization are preserved while hilar ligation is performed using a conventional stapler without need for additional transabdominal trocars.

Single trocar laparoscopic nephrectomy using magnetic anchoring and guidance system in the porcine model.

PURPOSE: We assessed the feasibility of single keyhole laparoscopic surgery using a novel transabdominal magnetic anchoring and guidance system platform in the porcine model. MATERIALS AND METHODS: A collaborative research group was formed to build a prototype system of magnetically anchored instruments for trocar-free laparoscopy. The design mandate was that the developed technology should be able to deploy into the insufflated abdomen through an existing 12 mm diameter trocar and then be moved into position in the peritoneum by manipulating external magnets. The magnetic anchoring and guidance system concept was advanced to a working prototype with a system of external magnetic anchors, an internal camera system and a hook cautery supported by an intra-abdominal robotic arm. This prototype system was then evaluated in vivo in a porcine laparoscopic nephrectomy model. RESULTS: Two nonsurvival porcine laparoscopic nephrectomies were successfully completed without complications via a single 15 mm transumbilical trocar using the prototype magnetic anchoring and guidance system camera and the magnetically anchored robotic arm cauterizer. A conventional laparoscopic grasper was used for retraction through the 15 mm trocar after magnetic anchoring and guidance system deployment. The renal artery and vein were transected with a conventional Endo-GIA stapler introduced through the 15 mm trocar. Procedure time was not recorded and blood loss was minimal. CONCLUSIONS: Single trocar laparoscopic nephrectomy using magnetically anchored instrumentation is technically feasible, demonstrating that intracorporeal instrument manipulation may overcome the limitations of current laparoscopic and robotic surgery by allowing unhindered intra-abdominal movement. This single access technique may be used with natural orifice surgery approaches and it has the potential to realize incision-free intra-abdominal surgery.

Trocar-less instrumentation for laparoscopy: magnetic positioning of intra-abdominal camera and retractor.

OBJECTIVE: To develop a novel laparoscopic system of moveable instruments that are positioned intra-abdominally and "locked" into place by external permanent magnets placed on the abdomen. SUMMARY BACKGROUND DATA: In conventional laparoscopy, multiple trocars are required because of the limited degrees of freedom of conventional instrumentation, and the limited working envelope (an inverted cone) created by the fulcrum motion around each port. While robotic systems can improve the number of degrees of freedom, they are restricted by even smaller working envelopes. METHODS: A collaborative research group from the Department of Urology and the Automation & Robotics Research Institute of the University of Texas, Arlington built a prototype system of magnetically anchored instruments for trocar-less laparoscopy. The only design mandate was that the developed technology be able to pass into the abdomen through one existing 12-mm diameter trocar. RESULTS: A transabdominal "magnetic anchoring and guidance system" (MAGS) platform was developed to incorporate instruments, retractors, and a controllable intra-abdominal camera. In vitro, the platform was able to anchor 375 and 147 g across porcine tissue 1.8 and 2.5 cm thick, respectively. The permanent magnet platforms were sufficiently strong to retract the porcine liver and securely anchor the camera. Its versatility was demonstrated by moving the camera to virtually any location in the peritoneum with no working envelope restrictions and the subsequent completion of porcine laparoscopic procedures with 2 trocars only. CONCLUSIONS: Trocar-less laparoscopy using magnetically anchored instruments is feasible and may expand intracorporeal instrument manipulation substantially beyond current-day capability. The ability to reduce the number of trocars necessary for laparoscopic surgery has the potential to revolutionize surgical practice.