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

An application research on a novel internal grasper platform and magnetic anchoring guide system (MAGS) in laparoscopic surgery

BACKGROUND

Laparoendoscopic single-site surgery and natural orifice transluminal endoscopic surgery attempt to reduce transabdominal port sites. These require all instruments to pass through a single access point, leading to instruments collide or work at unfamiliar angles. Thus, we designed an internal grasper under magnetic anchoring guide system (MAGS) platform and investigated its utility and operability.

METHODS

We measured the configuration for magnetic force decay over distance using a standardized, ex vivo laboratory testing apparatus. An electronic balance was used to measure the force of the gallbladder pull in ten patients with gallbladder stones. One pig (11 mm abdominal wall thickness) underwent a compressed trial of MAGS platform. The device was left in place for 20 min before tissue sections were harvested, and histologic assessment was performed. The utility and operability were investigated in four pigs (38-280 kg weight).

RESULTS

The magnetic attraction force decayed exponentially over distance; the force of pulling gallbladder was 7.46 ± 0.54 N. This pairing of components allowed for coupling to a theoretical distance of 10 mm. No gross tissue damage was observed. H-E stain showed no necrosis in all specimens. One failed due to wall thickness of 45 mm. Others showed the critical view, triangulation of instruments was obtained, and instrument collision or "sword fighting" was reduced.

CONCLUSIONS

The MAGS platform overcomes limitations such as collisions and lack of triangulation, reduces transabdominal port sites, and is easy to operate. However, our internal grasper requires the abdominal wall thickness below 10 mm.

Fine Tilt Tuning of a Laparoscopic Camera by Local Magnetic Actuation

Background. The magnetic surgical camera is an emerging technology having the potential to improve visualization without taking up port site space. However, tilting the point of view downward/upward can be done only by constantly applying a pressure on the abdomen. This study aims to test the hypothesis that the novel concept of local magnetic actuation (LMA) is able to increase the tilt range available for a magnetic camera without the need for deforming the abdominal wall. The hypothesis that 2-port laparoscopic nephrectomy in fresh tissue human cadavers could be performed by using the LMA camera is also tested. Methods. First, the 2 cameras were separately inserted, anchored, and moved inside the inflated abdomen. Tilting angles were quantified by image analysis while intra-abdominal pressure changes were monitored. Then, 5 two-port nephrectomies were performed by using the LMA camera while collecting quantitative outcomes. Results. The magnetic camera required a constant pressure on the magnetic handle to achieve an average ±20° tilt from the horizontal position, with an average of 7 mm Hg loss of intra-abdominal pressure. The LMA camera allowed for 75° of tilt from the horizontal position with a resolution of ±1°, without any need to deform the abdomen. All the nephrectomies were completed successfully within an average time of 11 minutes. Conclusion. LMA is an effective strategy to provide magnetic cameras with wide-range and high-resolution vertical motion without the need to deform the abdominal wall.

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.