Is Smaller Workspace A Limitation For Robot Performance In Laparoscopy?

Main Category: Urology / Nephrology
Also Included In: Clinical Trials / Drug Trials
Article Date: 16 Mar 2008 - 0:00 PDT

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UroToday.com - A study by the senior author C.K. Yeung and his colleagues from Hong Kong evaluated the limitation of a small working space in the performance of the da Vinci Surgical System. They wanted to globally assess the robotic system in a static environment based on the fact that they had difficulties performing specific tasks using the da Vinci robot in small cavities. The group had seven surgeons who were skilled using the da Vinci robot who performed five drills derived from the McGill Inanimate System for Training and Evaluation of Laparoscopic Skills. The five drills were performed in seven different sized wire framed cubes. The cube edge length ranged from 4 to 150 mm. Each of the surgical performances was evaluated by two reviewers for the drill achievement and time to completion was also recorded.

The group found that no task could be performed in the 40 mm edge cube because of several severe external collisions of the da Vinci surgical system. Only one of the drills could be performed in the 45 mm cube and therefore both the 40 and 45 mm edge cubes were excluded for the statistical analysis. The group found that 3 of the 5 drills could be accomplished in the 58 mm box and that all five of the exercises could be accomplished in the 60 mm cube with no external collisions. The remaining 70 mm, 80 mm and 150 mm cubes were found to be more than adequate to perform all the tasks. The results also showed that the global time and score depends on the box size. The larger the cube edge length, the better the score. They found that the surgeon could perform drills faster and more accurately in a larger workspace. However, the box size did not markedly affect the performance of the basic test, mostly because only one arm of the robot is moving at one time in the free space. They further found that in cases of complex tasks where the surgeon has to coordinate both arms, the tasks were a little bit more difficult and the time to complete the drill was prolonged.

The group then correlated their findings in the static environment what they had in their surgical experience. They state that had encountered difficulties performing vesicoscopic surgery with the da Vinci robot in patients with bladders smaller than 150 cm2. They go on to state that since they evaluated only one parameter that is the workspace, the limitation encountered by the da Vinci robot in the static environment is not different than that found in the patient. They further show that they had more difficulty with 5 mm instrumentation as compared to the 8 mm. I gave an editorial comment at the end that addressed the only disagreement I had with this paper which was their statement on how the static environment is not different from an actual patient environment. I find that during robotic surgery in the smaller patients, the abdominal wall is more forgiving than a complete static environment. Because of the elasticity of the anterior abdominal wall, transperitoneal surgery can be performed even in small patients as young as six months of age.

I do agree that the bladder itself is more of a static environment, and based on our experience with a purely laparoscopic approach to vesicoscopic reimplantation where a bladder capacity of less than 130 ml2 showed a higher rate of complication. Nonetheless, this is a great paper showing the physical limitations of the robot itself. We need to take these principles into a porcine lab setting where we can learn how to manipulate the static environment limitations to better suit our smaller pediatric patients.

Reported by UroToday.com Medical Editor Pasquale Casale, MD Assistant Professor, University of Pennsylvania University of Pennsylvania, Children's Hospital of Philadelphia

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