Magnetic Anchoring And Guidance System Research Articles

Deployable Tubular Mechanisms Integrated with Magnetic Anchoring and Guidance System

Deployable mechanism has received more attention in the medical field due to its simple structure, dexterity, and flexibility. Meanwhile, the advantages of the Magnetic Anchoring and Guidance System (MAGS) are further highlighted by the fact that the operators can remotely control the corresponding active and passive magnetic parts in vivo. Additionally, MAGS allows the untethered manipulation of intracorporeal devices. However, the conventional instruments in MAGS are normally rigid, compact, and less flexible. Therefore, to solve this problem, four novel deployable tubular mechanisms, Design 1 (Omega-shape mechanism), Design 2 (Fulcrum-shape mechanism), Design 3 (Archway-shape mechanism), and Design 4 (Scissor-shape mechanism) in this paper, are proposed integrated with MAGS to realize the laser steering capability. Firstly, this paper introduces the motion mechanism of the four designs and analyzes the motion characterization of each structure through simulation studies. Further, the prototypes of four designs are fabricated using tubular structures with embedded magnets. The actuation success rate, the workspace characterization, the force generation and the load capability of four mechanisms are tested and analyzed based on experiments. Then, the demonstration of direct laser steering via macro setup shows that the four mechanisms can realize the laser steering capability within the error of 0.6 cm. Finally, the feasibility of indirect laser steering via a macro-mini setup is proven. Therefore, such exploration demonstrates that the application of the deployable tubular mechanisms integrated with MAGS towards in vivo treatment is promising.

Laparoendoscopic single-site simple nephrectomy using a magnetic anchoring system in a porcine model.

PurposeMagnetic anchoring devices may reduce the number of port sites needed in laparoscopic surgery. In this study, we prospectively assessed the feasibility of using a magnetic anchoring and guidance system (MAGS) in laparoendoscopic single-site (LESS) surgery performed by novices.Materials and MethodsA total of 10 LESS simple nephrectomies were performed with or without MAGS in a nonsurvival porcine model by 6 operators with no previous LESS surgery experience. After installation of the homemade single port, an intra-abdominal magnet was fixed to the renal parenchyma with suturing and stabilized by an external magnet placed on the flank so that the position of the kidney could be easily changed by moving the external handheld magnet. The length of the procedure and any intraoperative complications were evaluated.ResultsOperative time (mean±standard deviation) was shorter in the group using the magnetic anchoring device (M-LESS-N) than in the group with conventional LESS nephrectomy (C-LESS-N) (63±20.8 minutes vs. 82±40.7 minutes, respectively). Although all nephrectomies were completed uneventfully in the M-LESS-N group, renal vein injury occurred during dissection of the renal hilum in two cases of C-LESS-N and was resolved by simultaneous transection of the renal artery and vein with an Endo-GIA stapler.ConclusionsLESS-N using MAGS is a feasible technique for surgeons with no LESS surgery experience. Taking into account the 2 cases of renal vein injury in the C-LESS-N group, the application of MAGS may be beneficial for overcoming the learning curve of LESS surgery.

Comparison Between Magnetic Anchoring and Guidance System Camera-Assisted Laparoendoscopic Single-Site Surgery Nephrectomy and Conventional Laparoendoscopic Single-Site Surgery Nephrectomy in a Porcine Model: Focus on Ergonomics and Workload Profiles

To compare surgeon-assessed ergonomic and workload demands of magnetic anchoring and guidance system (MAGS) laparoendoscopic single-site surgery (LESS) nephrectomy with conventional LESS nephrectomy in a porcine model. Participants included two expert and five novice surgeons who each performed bilateral LESS nephrectomy in two nonsurvival animals using either the MAGS camera or conventional laparoscope. Task difficulty and workload demands of the surgeon and camera driver were assessed using the validated National Aeronautics and Space Administration Task Load Index (NASA-TLX) questionnaire. Surgeons were also asked to score 6 parameters on a Likert scale (range 1=low/easy to 5=high/hard): procedure-associated workload, ergonomics, technical challenge, visualization, accidental events, and instrument handling. Each step of the nephrectomy was also timed and instrument clashing was quantified. Scores for each parameter on the Likert scale were significantly lower for MAGS-LESS nephrectomy. Mean number of internal and external clashes were significantly lower for the MAGS camera (p<0.001). Mean task times for each procedure were shorter for experts than for novices, but this was not statistically significant. NASA-TLX workload ratings by the surgeon and camera driver showed that MAGS resulted in a significantly lower workload than the conventional laparoscope during LESS nephrectomy (p<0.05). The use of the MAGS camera during LESS nephrectomy lowers the task workload for both the surgeon and camera driver when compared to conventional laparoscope use. Subjectively, it appears to also improve surgeons' impressions of ergonomics and technical challenge. Pending approval for clinical use, further evaluation in the clinical setting is warranted.

Laparoendoscopic Single Site (LESS) In Vivo Suturing Using a Magnetic Anchoring and Guidance System (MAGS) Camera in a Porcine Model: Impact on Ergonomics and Workload

To compare the ergonomics and workload of the surgeon during single-site suturing while using the magnetic anchoring and guidance system (MAGS) camera vs a conventional laparoscope. Seven urologic surgeons were enrolled and divided into an expert group (n=2) and a novice group (n=5) according to their laparoendoscopic single-site (LESS) experience. Each surgeon performed 2 conventional LESS and 2 MAGS camera-assisted LESS vesicostomy closures in a porcine model. A Likert scale (scoring 1-5) questionnaire assessing workload, ergonomics, technical difficulty, visualization, and needle handling, as well as a validated National Aeronautics and Space Administration Task Load Index (NASA-TLX) questionnaire were used to evaluate the tasks and workloads. MAGS LESS suturing was universally favored by expert and novice surgeons compared with conventional LESS in workload (3.4 vs 4.2), ergonomics (3.4 vs 4.4), technical challenge (3.3 vs 4.3), visualization (2.4 vs 3.3), and needle handling (3.1 vs 3.9 respectively; P<.05 for all categories). Surgeon NASA-TLX assessments found MAGS LESS suturing significantly decreased the workload in physical demand (P=.004), temporal demand (P=.017), and effort (P=.006). External instrument clashing was significantly reduced in MAGS LESS suturing (P<.001). The total operative time of MAGS LESS suturing was comparable to that of conventional LESS (P=.89). MAGS camera technology significantly decreased surgeon workload and improved ergonomics. Nevertheless, LESS suturing and knot tying remains a challenging task that requires training, regardless of which camera is used.

Single-site laparoscopic (SSL) cholecystectomy in human cadavers using a novel percutaneous instrument platform and a magnetic anchoring and guidance system (MAGS): reestablishing the “critical view”

SSL introduces ergonomic challenges while establishing the critical view during dissection of the Triangle of Calot (TOC). This study investigates the use of a novel percutaneous instrument platform and MAGS in performing SSL cholecystectomy with a technique that closely mimics four-port cholecystectomy. SSL cholecystectomy was performed on four female cadavers via a 15-18-mm incision made at the umbilicus for introduction of these devices and the working port. MAGS comprises an internal effector with a retractable monopolar cautery hook coupled across the abdominal wall to an external magnet held by the surgeon. The novel grasper was introduced percutaneously in the RUQ and comprises a 3-mm transabdominal shaft mated to a 5-mm end effector intracorporeally. Retraction was accomplished using the percutaneous grasper to manipulate the fundus and a standard 5-mm grasper at the umbilicus for the infundibulum. Dissection was performed by using a combination of the MAGS and a standard Maryland dissector. Total procedure time, time from procedure start to obtain a critical view of the TOC and clipping and dividing the cystic duct/artery, time for dissection of the gallbladder from the liver bed, and thickness of the abdominal wall at the umbilicus were measured. The critical view was obtained in each case, and all four procedures were completed successfully. Mean procedure time was 40 (range, 33-51) min; time from procedure start to obtaining the critical view and clipping and dividing the cystic duct/artery was 33 (range, 28-38) min, and time for dissection of the gallbladder from the liver bed was 6.7 (range, 3-13) min. The mean abdominal wall thickness was 1.9 (range, 1.5-2) cm. The use of a novel graspers and MAGS overcomes the limitations of SSL cholecystectomy and improves surgeon dexterity. Making SSL feel more like traditional laparoscopy will enable a wider adoption of this procedure in the community.

Tissue Compression Analysis for Magnetically Anchored Cautery Dissector During Single-Site Laparoscopic Cholecystectomy

IntroductionThe purpose of this study was to evaluate the histological effects of dynamic abdominal wall compression using the magnetic anchoring and guidance system (MAGS) platform. MethodsCholecystectomy 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. ResultsIn 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. DiscussionThis 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.

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

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. 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. 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. 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.

Single Access Laparoscopic Nephrectomy

Laparoscopic nephrectomy has assumed a central role in the management of kidney diseases. Laparoscopy, inspite of its lessmorbidity than open surgery, still requires several incisions. These incisions carry risks of bleeding, ventral hernia, damage to internalorgans and decreased cosmesis.An alternative to laparoscopy is the single access or keyhole surgery. This keyhole surgery utilizes the new laparoscopy access port(R-Port), single port access (SPA) procedure, one port umbilical surgery (OPUS), the belly button entry, natural orifice transluminalendoscopic surgery, and the magnetic anchoring and guidance system (MAGS) technology.

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

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. 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). 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. 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.

607 Magnetic Cautery Dissector for Single Site Laparoscopic Cholecystectomy in a Cadaver Model

The Magnetic Anchoring and Guidance System (MAGS) consists of an internal surgical device coupled across the abdominal wall and manipulated using an external handheld magnet. This video demonstrates a MAGS cautery dissector used in a cadaveric human cholecystectomy model. The gallbladder was retracted percutaneously and one laparoscopic instrument was used for assistance. The MAGS instrument was used to perform the entire dissection (18 minutes). The MAGS dissector provided excellent triangulation, obviated the need for additional laparoscopic instruments, minimized instrument conflicts, was compatible with human anatomical considerations, and greatly facilitated the single site approach.

Commentary on Complete transvaginal NOTES nephrectomy using magnetically anchored instrumentation

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. 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. 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 2 cases was 155 and 125 minutes, and blood loss was minimal. 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.

Role of Magnetic Anchors During Laparoendoscopic Single Site Surgery and NOTES

Evolution of minimally invasive techniques has generated an impetus in the surgical community to reduce the invasiveness of laparoscopic surgery. To achieve this goal, surgeons are either limiting the number of transabdominal trocars using laparoendoscopic single site surgery (LESS) or eliminating them completely using natural orifice translumenal endoscopic surgery (NOTES). The principle challenge with LESS or NOTES procedures is loss of triangulation, reduction in instrument working envelopes, and collision of conventional laparoscopic instrumentation. To overcome these limitations, surgical innovations, such as the use of deployable intracorporeal instrumentations, are necessary. Magnetic anchoring and guidance system (MAGS) technology is one approach for deployable instrumentation whereby intra-abdominal instruments can be maneuvered by the use of an external handheld magnet. Such a strategy would permit a single access port (either transabdominal or via a natural orifice) to serve as an entry point for multiple instruments. MAGS technology has thus far developed to incorporate instruments such as retractors, an intra-abdominal camera, and cautery dissectors. Continuous instrument development and rapid prototyping have created more robust MAGS platforms while potentially obviating the need for laparoscopic assistance. Animal work to date is promising with successful completion of a single-port nephrectomy as well as a NOTES transvaginal cholecystectomy in both nonsurvival and survival porcine models. As with all new technology, there will be an associated learning curve for these MAGS techniques that will necessitate more thorough elucidation before widespread use. The development of magnetically controlled and anchored intracorporeal surgical instruments, retractors, and cameras may advance surgical practice and improve patient care while meeting or exceeding the benefits of current-day fixed-trocar laparoscopy.

Complete Transvaginal NOTES Nephrectomy Using Magnetically Anchored Instrumentation

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. 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. 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. 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.

A novel magnetic anchoring and guidance system to facilitate single trocar laparoscopic nephrectomy

A transabdominal magnetic anchoring and guidance system (MAGS) deploys multiple instruments through a single 15-mm diameter, transabdominal trocar. These instruments are positioned in the peritoneal cavity and controlled by externally placed magnets to reduce the need for multiple transabdominal trocars. To assess the feasibility of MAGS technology in a single keyhole, complex laparoscopic procedure, nonsurvival porcine nephrectomies were completed without complications via a single 15-mm transumbilical trocar using a prototype MAGS camera and a magnetically anchored, robotic arm cauterizer.

Single access laparoscopic nephrectomy

Laparoscopic nephrectomy has assumed a central role in the management of benign and malignant kidney diseases. While laparoscopy is less morbid than open surgery, it still requires several incisions each at least 1-2 cm in length. Each incision carries morbidity risks of bleeding, hernia and/or internal organ damage, and incrementally decreases cosmesis. An alternative to conventional laparoscopy is single access or keyhole surgery, which utilizes magnetic anchoring and guidance system (MAGS) technology or articulating laparoscopic instruments. These technical innovations obviate the need to externally space trocars for triangulation, thus allowing for the creation of a small, solitary portal of entry into the abdomen. Laboratory and early clinical series demonstrate feasibility as well as safe and successful completion of keyhole nephrectomy. Future work is necessary to improve existing instrumentation, increase clinical experience, assess benefits of this surgical approach, and explore other potential applications for this technique.

Completely transvaginal NOTES cholecystectomy using magnetically anchored instruments

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). 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. 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. 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.

Short-Term Survival Outcomes Following Transvaginal NOTES Cholecystectomy Using Magnetically Anchored Instruments

Introduction: Optimal techniques for Natural Orifice Translumenal Endoscopic Surgery (NOTES) are evolving. We previously reported successful transvaginal NOTES cholecystectomy in a non-survival porcine model using a Magnetic Anchoring and Guidance System (MAGS). The purpose of this study was to determine short-term survival outcomes following transvaginal cholecystectomy. Methods: Procedures were performed in pigs (n = 3, 29-34 kg) survived for 14 days. The abdomen, vagina, and perineum were prepped with betadyne; sterile instruments were used.