Monopolar stray energy in robotic surgery

Stray energy injury during robotic versus laparoscopic inguinal hernia repair: a randomized controlled trial

BACKGROUND

Stray energy transfer from monopolar instruments during laparoscopic surgery is a recognized cause of potentially catastrophic complications. There are limited data on stray energy injuries in robotic surgery. We sought to characterize stray energy injury in the form of superficial burns to the skin surrounding laparoscopic and robotic trocar sites. Our hypothesis was that stray energy burns will occur at all laparoscopic and robotic port sites.

METHODS

We conducted a prospective, randomized controlled trial of patients undergoing elective unilateral inguinal hernia repair at a VAMC over a 4-year period. Surgery was performed via transabdominal preperitoneal approach either laparoscopic-assisted (TAPP) or robotic-assisted (rTAPP). A monopolar scissor was used to deliver energy at 30W coagulation for all cases. At completion of the procedure, skin biopsies were taken from all the port sites. A picro-Sirius red stain was utilized to identify thermal injury by a blinded pathologist.

RESULTS

Over half (54%, 59/108) of all samples demonstrated thermal injury to the skin. In the laparoscopic group, 49% (25/51) samples showed thermal injury vs. 60% (34/57) in the robotic group (p = 0.548). The camera port was the most frequently involved with 68% (13/19) rTAPP samples showing injury vs. 47% (8/17) in the TAPP group (p = 0.503). There was no difference in the rate of injury at the working port site (rTAPP 53%, 10/19 vs. TAPP 47%, 8/17; p = 0.991) or the assistant port site (rTAPP 58%, 11/19 vs. TAPP 53%, 9/17; p = 0.873).

CONCLUSIONS

Stray energy causes thermal injury to the skin at port sites in the majority robotic laparoscopic TAPP inguinal hernia repairs. There is no difference in stray energy transfer between the laparoscopic and robotic platform. This is the first study to confirm in-vivo transfer of stray energy during robotic surgical procedures. More study is needed to determine the clinical significance of these thermal injuries.

Robotic stray energy with constant-voltage versus constant-power regulating electrosurgical generators

INTRODUCTION

Stray energy from surgical energy instruments can cause unintended thermal injuries. There are no published data regarding electrosurgical generators and their influence on stray energy transfer during robotic surgery. There are two approved generators for the DaVinci Xi robotic platform: a constant-voltage regulating generator (cVRG) and a constant-power regulating generator (cPRG). The purpose of this study was to quantify and compare stray energy transfer in the robotic Xi platform using a cVRG versus a cPRG.

METHODS

An ex vivo bovine model was used to simulate a standard multiport robotic surgery. The DaVinci Xi (Intuitive Surgical, Sunnyvale, CA) robotic platform was attached to a trainer box using robotic ports. A 5 s, open-air activation of the monopolar scissors was done with commonly used electrosurgical settings using a cPRG (ForceTriad, Covidien-Medtronic, Boulder, CO) or cVRG (ERBE VIO 300 dV 2.0, ERBE USA, Marietta, GA). Stray energy transfer was quantified as the change in tissue temperature (°C) nearest the tip of the assistance grasper (which was not in direct contact with the active monopolar scissors).

RESULTS

Stray energy transfer occurred with both generators. Utilizing common, comparable settings for standard coagulation, significantly less stray energy was transferred with the cVRG versus cPRG (4.4 ± 1.6 °C vs. 41.1 ± 13.0 °C, p < 0.001). Similarly, less stray energy was transferred using cut modes with the cVRG compared to the cPRG (5.61 ± 1.79 °C vs. 33.9 ± 18.4 °C, p < 0.001).

CONCLUSION

Stray energy transfer increases tissue temperatures more than 45C in the DaVinci Xi robotic platform. Low voltage modalities, such as cut or blend; as well as a cVRG generator, significantly reduces stray energy. Robotic surgeons can minimize the risk of stray energy injuries by using these low risk modes and/or generator.