Is the image "right" for everyone? Introduction to the parallax effect in laparoscopic surgery

[Evidence, Availability and Future Visions in Simulation in General and Visceral Surgery]

Practice makes perfect - a saying that everyone has certainly heard. Surgeons of all levels of training can demonstrably practice to some extent on simulators. This training outside the operating theatre and independent of patients makes sense, both ethically and financially. Although the effectiveness of simulation in surgery has been proven several times, simulation training is not a mandatory part of surgical specialist training in Germany. Simulation covers a very wide range in terms of application, effort and costs. This review is intended to give an overview of the systems and their areas of application and the target group. The focus lies on the commonly available systems and possible advantages and disadvantages. Practical skills are in the foreground and all three pillars of general and visceral surgery - conventional techniques, laparoscopy and robotics - are taken into account. However, simulators alone do not achieve cost-benefit effectiveness. The full potential of such an investment can only be exploited with a site-specific, structured training concept in which simulation training according to the post-graduate year and appropriate allocation to surgeries in the operating room are closely interlinked. It should always be possible to train basic skills on site. The significant additional costs for complex simulation systems are possible, depending on the financial resources, or should be purchased in a network or for national courses. The techniques of immersive virtual reality in combination with artificial intelligence and deformation algorithms will certainly play a decisive role for the future of simulation, whereby the use of the available systems must be a primary goal. The integration of simulation into specialist training should be striven for, not least in order to justify the costs.

Augmented reality in liver surgery

INTRODUCTION

During an operation, augmented reality (AR) enables surgeons to enrich their vision of the operating field by means of digital imagery, particularly as regards tumors and anatomical structures. While in some specialties, this type of technology is routinely ustilized, in liver surgery due to the complexity of modeling organ deformities in real time, its applications remain limited. At present, numerous teams are attempting to find a solution applicable to current practice, the objective being to overcome difficulties of intraoperative navigation in an opaque organ.

OBJECTIVE

To identify, itemize and analyze series reporting AR techniques tested in liver surgery, the objectives being to establish a state of the art and to provide indications of perspectives for the future.

METHODS

In compliance with the PRISMA guidelines and availing ourselves of the PubMed, Embase and Cochrane databases, we identified English-language articles published between January 2020 and January 2022 corresponding to the following keywords: augmented reality, hepatic surgery, liver and hepatectomy.

RESULTS

Initially, 102 titles, studies and summaries were preselected. Twenty-eight corresponding to the inclusion criteria were included, reporting on 183patients operated with the help of AR by laparotomy (n=31) or laparoscopy (n=152). Several techniques of acquisition and visualization were reported. Anatomical precision was the main assessment criterion in 19 articles, with values ranging from 3mm to 14mm, followed by time of acquisition and clinical feasibility.

CONCLUSION

While several AR technologies are presently being developed, due to insufficient anatomical precision their clinical applications have remained limited. That much said, numerous teams are currently working toward their optimization, and it is highly likely that in the short term, the application of AR in liver surgery will have become more frequent and effective. As for its clinical impact, notably in oncology, it remains to be assessed.

Associations Between Binocular Depth Perception and Performance Gains in Laparoscopic Skill Acquisition

The ability to perceive differences in depth is important in many daily life situations. It is also of relevance in laparoscopic surgical procedures that require the extrapolation of three-dimensional visual information from two-dimensional planar images. Besides visual-motor coordination, laparoscopic skills and binocular depth perception are demanding visual tasks for which learning is important. This study explored potential relations between binocular depth perception and individual variations in performance gains during laparoscopic skill acquisition in medical students naïve of such procedures. Individual differences in perceptual learning of binocular depth discrimination when performing a random dot stereogram (RDS) task were measured as variations in the slope changes of the logistic disparity psychometric curves from the first to the last blocks of the experiment. The results showed that not only did the individuals differ in their depth discrimination; the extent with which this performance changed across blocks also differed substantially between individuals. Of note, individual differences in perceptual learning of depth discrimination are associated with performance gains from laparoscopic skill training, both with respect to movement speed and an efficiency score that considered both speed and precision. These results indicate that learning-related benefits for enhancing demanding visual processes are, in part, shared between these two tasks. Future studies that include a broader selection of task-varying monocular and binocular cues as well as visual-motor coordination are needed to further investigate potential mechanistic relations between depth perceptual learning and laparoscopic skill acquisition. A deeper understanding of these mechanisms would be important for applied research that aims at designing behavioral interventions for enhancing technology-assisted laparoscopic skills.

Improving vision for surgeons during laparoscopy: the Enhanced Laparoscopic Vision System (ELViS)

BACKGROUND

For many abdominal surgical interventions, laparotomy has gradually been replaced by laparoscopy, with numerous benefits for the patient in terms of post-operative recovery. However, during laparoscopy, the endoscope only provides a single viewpoint to the surgeon, leaving numerous blind spots and opening the way to peri-operative adverse events. Alternative camera systems have been proposed, but many lack the requisite resolution/robustness for use during surgery or cannot provide real-time images. Here, we present the added value of the Enhanced Laparoscopic Vision System (ELViS) which overcomes these limitations and provides a broad view of the surgical field in addition to the usual high-resolution endoscope.

METHODS

Experienced laparoscopy surgeons performed several typical procedure steps on a live pig model. The time-to-completion for surgical exercises performed by conventional endoscopy and ELViS-assisted surgery was measured. A debriefing interview following each operating session was conducted by an ergonomist, and a System Usability Scale (SUS) score was determined.

RESULTS

Proof of concept of ELVIS was achieved in an animal model with seven expert surgeons without peroperative adverse events related to the surgical device. No differences were found in time-to-completion. Mean SUS score was 74.7, classifying the usability of the ELViS as "good". During the debriefing interview, surgeons highlighted several situations where the ELViS provided a real advantage (such as during instrument insertion, exploration of the abdominal cavity or for orientation during close work) and also suggested avenues for improvement of the system.

CONCLUSIONS

This first test of the ELViS prototype on a live animal model demonstrated its usability and provided promising and useful feedback for further development.

Structured assessment of laparoscopic camera navigation skills: the SALAS score

BACKGROUND

Tools are needed to assess laparoscopic camera navigation (LCN) in the operating room. Here, we aimed to develop an objective rating scale for LCN.

STUDY DESIGN

We defined the following key aspects of LCN: operational field centering, correct angle of the horizon, correct instrument visualization, verbal commands from the operating surgeon, and manual corrections from the operating surgeon. We then developed a score based on intraoperative error evaluation from intraoperative recordings of 80 procedures. Finally, the newly developed score was validated by four different raters using video-based analysis of 20 elective laparoscopic cholecystectomies.

RESULTS

We developed and validated a tool for the structured assessment of laparoscopic assistant skills (SALAS). This score showed good internal consistency, with a Cronbach's alpha of > 0.7. Intraclass correlation revealed a low interrater variability (ICC 0.866) for the total score. Comparison of experienced and inexperienced camera assistants revealed significantly better SALAS scores for experienced assistants (p < 0.05).

CONCLUSION

Our present results show that SALAS score is valid, reliable, and practicable. This score can be used for future investigations of camera navigation efficiency and training.