ROBOTIC LAPAROSCOPIC SURGERY: A Comparison of The Da Vinci and Zeus Systems
AJIT M VAZE
Hon. Urologist and Andrologist, Jaslok Hospital, Sir HN Hospital, Lilavati Hospital and Research Centre, Mumbai.
Laparoscopy has changed the way we perceive and practice surgery. Although patients benefit considerably from the minimal invasion, laparoscopic surgeons are challenged with somewhat constrained technical abilities. As increasingly complex laparoscopic procedures are undertaken, optimization of laparoscopic efficacy takes on added importance and urgency. Recent advances in robotic and computer technology may elevate laparoscopic surgery to yet another level by enhancing human performance using master-slave manipulators. Currently, two surgical telemanipulators are capable of performing remote telerobotic surgery : The da Vinci robotic surgical system (Intuitive Surgical, Mountain View, Calif) and the Zeus robotic surgical system (Computer Motion, Goleta, Calif).
The da Vinci system consists of three components a surgeon console with an integrated three-dimensional display stereo viewer, a robotic manipulator with three cartmounted arms (one arm for the camera, two arms for the 8 mm instruments), and a vision cart. Visualization is obtained by two three chip cameras mounted within one integrated, three-dimensional 12 mm stereo endoscope with two separate optical channels. The laparoscope is controlled by moving the master robotic handles. The operative images are transmitted to a high resolution binocular display at the surgeon console. Unique laparoscopic instrument tips, called "Endo wrist instruments", provide articulated motion with a full seven degrees of freedom inside the abdominal cavity. Tip articular mimic the up/down ("PITCH") and the side-to-side ("YAW") flexibility of the human wrist. Instrument tips are aligned with the instrument controllers electronically to provide optimal hand-eye orientation and natural operative capability.
Fig.1 Digital enhancing quality vedio camera. Fig.2 3-D Systems. Fig.3 Robotic cum in progress Fig.4 Tele robotic system Fig.5 Da-vinci system. Fig.6 3-D surgery in progress. Fig.7 3-D Telescope Fig.8 3-D glasses Fig. 9 Telerobotic system Fig. 10 Digital date organiser
The latest version of the Zeus system (z2p) has three major components. Surgeon console, computer controller, and three interactive robotic arms. While seated at the surgeon console, the remote surgeon manipulates the robotic handles attached to the console. The movements are precisely filtered, scaled, and relayed to the computer controller, which transmits these movements across an electromechanical interface to the robotic arms and instruments. The 10 mm three-dimensional laparoscope is controlled by a voice-activated automated endoscopic surgical optimal positioning (AESOP) arm, and two robotic arms control the 5 mm laparoscopic instrumentsused to perform the procedure. At the time of this study, the laparoscopic instruments did not have an articulating tip. The initial version of the Zeus system did not have three dimensional laparoscopic vision. System electronics permit motion scaling in both robotic systems. An assistant remained on site at the animal operating table only to exchange various robotic instruments, including the needle driver, graspers electrosurgical J-hook, tissue dissector, and scissors, at the voice command of the remote surgeon and to troubleshoot the robotic arms. For robotic laparoscopic nephrectomy. The renal artery and vein were mobilized individually. A previously inserted 2-0 silk tie was used to triple ligate the renal artery and double ligate the renal vein. The ureter was divided and the kidney mobilized circumferentially. For robotic laparoscopic adrenalectomy, adrenal mobilization, including control of the main adrenal vein, was achieved by electrocautery. For robotic pyeloplasty, the upper ureter was mobilized and obliquely transected in closes proximity to the renal hilum. Unstented anastomotic suturing was performed robotically using two running 5-0 biosyn sutures. The entire pyeloplasty procedure was performed telerobotically from the remote workstation in both the da Vinci system group and the Zeus system group.
The transition from a large single open incision to a few small keyhole incisions to gain access to the abdominal cavity has revolutionized dimensional visualization with technical manoeuvres performed efficiently, ergonomically, and with excellent tactile feedback. However, in conventional laparoscopy, the operator is faced with certain constraints such as the lack of three-dimensional visualization, limited tactile feedback, restriction in the degrees of freedom of movements because of nonarticulating laparoscopic instruments and a fixed point of insertion, mirroring of hand movements, potential inaccuracy during delicate reconstruction because of natural hand tremor, awkward hand-eye coordination, and interior ergonomics. Some of these impediments may be corrected by using the principle of a master-slave manipulator, in which the handle of the instrument and its tip are physically disconnected. All movements from the instrument handles ("Master Unit") are transformed into electronic signals filtered and scaled and transmitted in real time to the "Slave unit", a motorized robotic instrument tips. The two current commercially available telemanipulator systems were evaluated in this study. The da Vinci system uses a kinematic (or joint movement) structure, allowing the surgeon to use open surgical movements and techniques while maintaining the benefits of access through keyhole incision. The instruments are capable of delivering a total of seven degrees of freedom (including grip) : the surgical manipulator delivers three degrees of freedom (Yaw, Pitch and Insertion), and an additional three degrees of freedom are delivered by the endo wrist instruments. This cable-driven mechanical endo-wrist instruments articulate the instrument tips in any direction, delivering the dexterity of the surgeonís hand and wrist to the operative site. In our study, endowrist instruments allowed for an impressively complete range of motion of the instrument tips, readily facilitating tissue dissection and optimal needle positioning, comparable to open surgery. In other words, the system is intuitively designed to incorporate open surgical manoeuvres into laparoscopic techniques. The da Vinci system incorporates a natural stereoscopic vision which provides the eyes of the user with a viewpoint derived from a two-channel endoscope. Each channel is sampled with its own three-chip NTSC video camera and then displayed on its own cathode ray tube (CRT) display. Alike conventional laparoscopy or the Zeus system, in which the surgeon can see the rest of the operating room in addition to the endoscopic view on the television monitor, in the da Vinci system, the surgeon gets the impression of being completely immersed in the endoscopic operative field without any external bearing or visual cues whatsoever. This makes for intuitive hand-eye coordination and superb depth perception during tissue handling and suturing. The z2p Zeus system offers somewhat different features in terms of visualization and instrumentation. The Zeus system used in this study provided three-dimensional visualization and instruments with nonarticulating tips. The surgeonís hand movements resemble laparoscopic, not open, movements. This system allow 5 degrees of freedom within the abdominal cavity : horizontal, vertical in and out, rotational, and grasping. The z2p Zeus system incorporates improved voice-recognition technology and stereovision using passive eye wear. In this passive eye system, the two small shutter-glasses are replaced by one large shutter-glass that is fixed to the television screen. The shutter-glass polarized the two pictures on the screen into a right-polarized picture for the right eye and a left-polarized picture for the left eye. Although Zeus system-based procedures required a longer operative time, both systems provided high visual magnification, movement scaling, and tremor filtering, which allowed for precise tissue dissection. However, interference between the robotic arms or between the arms and the body of the animal occurred during dissection on a few occasions in both systems. Future miniaturization of the architecture of the arms should solve this problem. Certain limitations in the current robotic systems and its end-effectors were evident. The lack of tactile feedback was a major drawback in both systems. Current haptic sensing technology allows for detection of approximately 0.6 N of force, which is equivalent to a 4 mm deflection of soft tissue. This degree of sensitivity may be insufficient for performing robotic microvascular procedures clinically. As such, novel software programmes need to be developed to incorporate force (haptic) feedback seamlessly with the three-dimensional visual feed-back. A critical question is how the different robotic surgical systems will perform in clinical cases. Another drawback is the cost of these system, currently ranging from $75,000 to $1 million. Presently, latency is the biggest hurdle in delivering telepresence surgery, with a time delay of greater than 700 ms making telesurgical manipulation impractical. Instantaneous transmission using very high bandwidth communication channels will be integral to successful telesurgery.
Urologic laparoscopic procedures can be performed effectively using either the da Vinci robotic system or the Zeus robotic surgical system. In this limited study, the learning curve and operative time were shorter and the intraoperative technical movements appeared more inherently intuitive with the da Vinci system. Although suitable for select clinical applications at present, further advances in device technology are needed to provide viable force feedback and a greater selection of appropriate instrument tips.
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