Surgical Endoscopy And Other Interventional Techniques

, Volume 20, Issue 1, pp 135–138

Mobile in vivo camera robots provide sole visual feedback for abdominal exploration and cholecystectomy

Authors

  • M. E. Rentschler
    • University of Nebraska, N104 Walter Scott Engineering Center
  • J. Dumpert
    • University of Nebraska, N104 Walter Scott Engineering Center
  • S. R. Platt
    • University of Nebraska, N104 Walter Scott Engineering Center
  • S. I. Ahmed
    • University of Nebraska Medical Center, 983280 Nebraska Medical Center
  • S. M. Farritor
    • University of Nebraska, N104 Walter Scott Engineering Center
    • University of Nebraska Medical Center, 983280 Nebraska Medical Center
Article

DOI: 10.1007/s00464-005-0205-7

Cite this article as:
Rentschler, M.E., Dumpert, J., Platt, S.R. et al. Surg Endosc (2006) 20: 135. doi:10.1007/s00464-005-0205-7

Abstract

The use of small incisions in laparoscopy reduces patient trauma, but also limits the surgeon’s ability to view and touch the surgical environment directly. These limitations generally restrict the application of laparoscopy to procedures less complex than those performed during open surgery. Although current robot-assisted laparoscopy improves the surgeon’s ability to manipulate and visualize the target organs, the instruments and cameras remain fundamentally constrained by the entry incisions. This limits tool tip orientation and optimal camera placement. The current work focuses on developing a new miniature mobile in vivo adjustable-focus camera robot to provide sole visual feedback to surgeons during laparoscopic surgery. A miniature mobile camera robot was inserted through a trocar into the insufflated abdominal cavity of an anesthetized pig. The mobile robot allowed the surgeon to explore the abdominal cavity remotely and view trocar and tool insertion and placement without entry incision constraints. The surgeon then performed a cholecystectomy using the robot camera alone for visual feedback. This successful trial has demonstrated that miniature in vivo mobile robots can provide surgeons with sufficient visual feedback to perform common procedures while reducing patient trauma.

Keywords

CholecystectomyExplorationIn vivoLaparoscopyMobileRobots

A primary patient advantage of minimally invasive surgery is reduced trauma, as compared to conventional open surgery, through the use of small incisions. However, these small incisions do not allow the surgeon to view or touch the surgical environment directly, and they constrain the motion of the end point of the tools and cameras to arcs of a sphere whose center is the insertion point. Such limitations have slowed the expanded use of laparoscopic techniques for complex procedures.

Several robot systems exist that help increase the surgeon’s dexterity by precisely manipulating laparoscopic tools. Such systems generally consist of a multi-arm robot external to the patient. Each arm manipulates a tool (or camera) that is teleoperated by a surgeon. The robots can filter the natural tremor present in the human hand, correct for the effects of motion reversal, and perform motion scaling to provide greater instrument control. Such systems, generally large and expensive, still are fundamentally constrained by the limited access to the abdominal cavity provided by small access ports.

A potentially new approach to laparoscopy involves inserting miniature robotic assistants entirely into the patient. Such wireless in vivo robots will provide vision and task assistance without being constrained by the entry incision. Robotic cameras inside the body can allow for better planning of trocar insertion and tool placement, while providing additional visual cues that help the surgeon to explore and understand the surgical environment more easily and completely.

These types of minirobots likely will fall into two main categories: fixed base and mobile. Fixed-base robots are positioned directly by the surgeon, and will be used predominantly to supply visual feedback for local procedures or to provide an overview of the surgical environment. Mobile robots will be capable of traversing abdominal organs to explore the abdominal cavity and provide sensor feedback (e.g., feedback on visual and environmental conditions). These robots, positioned via remote commands from the surgeon, will be extremely useful for identifying the location of the complication and providing task assistance. This mobile capability will be a key feature in the future. As techniques develop to perform procedures with fewer incisions so as to reduce patient trauma further, the surgeon will become less able to position fixed-base in vivo robots via direct manipulation.

Materials and methods

The use of robotics currently is recognized as the major driving force for the future technological advance of minimally invasive surgery [1, 9, 10]. Currently, robots used in surgery are implemented from outside the body, and therefore are still fundamentally constrained by the small access ports. Moreover, each of the robotic arms is necessarily long and bulky to accommodate the range of motion required to maneuver the long instruments attached to each arm. Large excursion arcs of the arms lead to collisions outside the patient, and improper placement of the access ports leads to collisions inside the patient [1]. Each arm requires a separate access port. Hence the number of incisions is not reduced, as compared with traditional nonrobotic laparoscopy. These incisions are made as part of the setup procedure for the robot, so the problems associated with injuries caused by access port insertion [11, 12] remain unaddressed.

Similarly, a limited range of motion for the robotic camera still can result in obstructed or incomplete visual feedback. Tool changes still require removal of the existing tool and reinsertion of the new one, adding to the overall surgical time and adversely affecting the efficiency of the operation [2, 3]. Until visual feedback and dexterity improve, the enormous potential for minimally invasive surgery to replace many open conventional procedures will not be fully realized.

Initial work has begun to address in vivo robotic manipulators and visual feedback [7]. Several prototype fixed-base in vivo camera robots have been used in conjunction with a standard laparoscope during porcine (swine) cholecystectomies to provide the surgeon with additional visual feedback [4]. Findings have shown the quality of the images from these robot cameras to be comparable with that of current laparoscopic systems [8].

A wheeled mobile robot (Fig. 1) also has been developed that has the ability to traverse abdominal organs. This robot is 15 mm in diameter and 75 mm in length. Two helical wheels, independently driven by DC motors, are designed to provide sufficient traction without causing tissue damage [5]. A tail prevents the robot from spinning, but allows it to flip when reversing directions. This 25-g robot is capable of producing drawbar forces equal to its weight [6]. This allows it to climb hilly and deformable terrain, as demonstrated during porcine tests.
https://static-content.springer.com/image/art%3A10.1007%2Fs00464-005-0205-7/MediaObjects/464_2005_205_f1.jpg
Fig. 1

The 15-mm-diameter mobile in vivo robot wheel design showing the ability of the robot to traverse organs three times its height without causing tissue damage.

A second wheeled mobile robot (Fig. 2) was developed based on the successful wheel design of the 15-mm robot. This mobile adjustable-focus robotic camera (MARC) is 20 mm in diameter and incorporates an on-board adjustable-focus video camera system. Two DC motors independently control each wheel, providing the robot with forward, reverse, and turning capabilities. The 50-g MARC robot is 100 mm in length with a helical wheel profile and a stabilizing tail. The design of the tail allows it to be lifted and flipped in reversing the direction of travel. This allows the robot to tilt its camera 15° without changing the position of the wheels. The adjustable-focus camera system provides a mobile viewing platform entirely within the abdominal cavity. Both of these prototype mobile robots are tethered for power. Future designs will be wireless.
https://static-content.springer.com/image/art%3A10.1007%2Fs00464-005-0205-7/MediaObjects/464_2005_205_f2.jpg
Fig. 2

The 20-mm diameter mobile adjustable-focus robotic camera (MARC) designed to accommodate an adjustable-focus camera mechanism while maintaining the successfully designed helical wheel profile.

Results

To the authors’ knowledge, tests conducted with the MARC robot represent the first use of in vivo wheeled robots during surgery to provide the sole source of visual feedback to the surgeon. The MARC robot was inserted through a fabricated trocar into an anesthetized pig, and the abdominal cavity then was insufflated with carbon dioxide. The trocar was designed to accommodate the 20-mm diameter of the MARC robot. Future robots will use standard 15-mm laparoscopic trocars.

Next, a standard trocar was inserted to provide an additional tool port. A third port also was created to accommodate a standard laparoscope. The laparoscope provided lighting for the MARC robot’s camera, but the surgeon did not use visual feedback from the laparoscope during the procedure.

The surgical team used MARC to help plan and view the additional trocar insertions and laparoscopic tool placements (Fig. 3). The multiple achievable views from the MARC camera allowed the surgeon to plan and place trocars safely and appropriately in the abdominal wall of the animal.
https://static-content.springer.com/image/art%3A10.1007%2Fs00464-005-0205-7/MediaObjects/464_2005_205_f3.jpg
Fig. 3

After insertion into the abdominal cavity, the mobile adjustable-focus robotic camera (MARC) was used to help plan and safely insert trocars and laparoscopic tools.

In addition, MARC was used to explore the abdominal cavity (Fig. 4). The wheeled mobility allowed the surgeon to explore various regions within the abdominal cavity, whereas the adjustable-focus camera allowed the surgeon to focus on a specific portion of the region of interest. These video cues allowed the surgeon to navigate the abdominal environment safely and effectively. The ability to maneuver within the abdominal cavity provided additional frames of reference and perspectives not available with a standard laparoscope.
https://static-content.springer.com/image/art%3A10.1007%2Fs00464-005-0205-7/MediaObjects/464_2005_205_f4.jpg
Fig. 4

The mobile adjustable-focus robotic camera (MARC) robot was used to explore the abdominal cavity while providing the surgeon with visual feedback.

Finally, a cholecystectomy was performed with MARC providing the only visual feedback available to the surgeon (Fig. 5) (i.e., the video from the laparoscope was not viewed by the surgeon). The ability of the robot to tilt the adjustable-focus camera 15° without changing the position of the wheels proved extremely useful in retraction of the liver. The adjustable-focus capability of the camera system allowed the surgeon to have a better understanding of depth.
https://static-content.springer.com/image/art%3A10.1007%2Fs00464-005-0205-7/MediaObjects/464_2005_205_f5.jpg
Fig. 5

During the cholecystectomy, the mobile adjustable-focus robotic camera (MARC) provided sole visual feedback to the surgeon. The robot allowed the surgeon to determine depth of field using the adjustable-focus camera, and provided the surgeon with multiple angles of view by tilting the camera during the liver retraction.

Discussion

This successful trial shows the great promise of mobile in vivo robotics, and the projected outcomes have the potential for important advancements in minimally invasive surgery. These tests have demonstrated that it is possible to perform a common laparoscopic procedure using an in vivo camera system as the sole source of visual feedback. This has the potential to reduce patient trauma by eliminating the need for a camera port and instead inserting mobile in vivo camera robots, such as MARC, through one of the tool ports. Although the initial prototype was slightly larger than a traditional trocar, future robots will be smaller in size, have no tethers, and incorporate additional sensors.

Miniature in vivo robots will be far more agile inside the abdominal cavity than the current generation of large and expensive external telemanipulators. Current laparoscopic robots are bulky and unwieldy and cannot be easily transported. Because of their cost, they typically are designed for multiple surgical procedures with interchangeable instrument arms. Future miniature robots may be designed for each specific task. Because they are small, multiple robots can be used simultaneously. Although it might be possible in the future for such robots to perform the entire procedure, current technology is more appropriate for use of the robots as assistants during surgery to aid in visualization and micromanipulation. Equipped with additional sensors, they also will be able to explore and provide tissue diagnosis.

The long-term goal is to use in vivo robots to improve the quality and safety of laparoscopic surgery. The rationale that underlies this research is that the ability to view the surgical field from multiple angles using dexterous manipulators not constrained by small incisions in the abdominal wall will help surgeons to realize the full potential of laparoscopic surgery.

Copyright information

© Springer Science+Business Media, Inc. 2005