|Year : 2005 | Volume
| Issue : 2 | Page : 74-78
Robots for minimally invasive urology
A Shrivastava, M Menon
Vattikuti Urology Institute, K9 Henry Ford Health Systems, Detroit, MI 48202, USA
2799 West Grand Boulevard, Vattikuti Urology Institute,K9 Henry Ford Health Systems, Detroit,MI 48202
|How to cite this article:|
Shrivastava A, Menon M. Robots for minimally invasive urology. Indian J Urol 2005;21:74-8
Robots: form assembly lines to operating room
The term robot is derived from a Czech word robota meaning 'forced labor.' The concept of robot can be traced back to 3000 b.c. Ancient Greeks and Egyptians built water clocks called clepsydra that supposedly served as oracles. The famous renaissance artist Leonardo daVinci was said to have a mechanical lion that walked and roared.
The machines performing tasks like human were looked at with fear and awe in nineteenth and early twentieth century as reflected by popular literature of the times. Monstrous machines killing humans or overtaking control of human race was a popular science fiction theme. Mary Shelley's novel Frankenstein in 1817 and Karel Capek's play RUR - Rossum's Universal Robot in 1921 were prominent examples of human creations made of flesh or metal harming the society. Capek is also credited with introduction of the term robot.
Robots as we know them today were developed after World War II due to increased need of automation in automobile. General motors were the first major companies to ever use a robot in 1961. George C. Devol and Joseph F. Engelberger, founders of the Unimation Corp., installed the Unimate robot at the plant. This 'machine unloaded a die-casting machine, quenched the hot component, and delivered it to a trim press for flash removal.' Finally hazardous tasks, such as machine tool loading, and punch pass operation, lifting heavy automobile bodies, and boring and repetitive jobs, such as spray-painting car bodies could be avoided by the use of the robots.
One of the types of robotics invented was known as telecherics. Telecherics, developed initially at argonne national laboratories, was the use of mechanical arms to emulate the motions of an operator from a distance. These master-slave manipulators place a human in the control loop, thus taking advantage of the human's cognitive and sensorimotor skills and robots fine motor abilities.
Orthopedics and neurosurgery were the first specialties to test the concept that the robots may be more precise than humans. These surgeons perform procedures on organs that provide landmarks as reference points, which helped navigating the robot. An orthopedic system RobotDoc (Integrated Surgical Systems, Sacramento, CA) used for preparing proximal femur to accept an uncemented total hip prosthesis can perform reaming of bone 10 times more accurate than manual reaming and achieves 90% surface contact with prosthesis.
In early 1980s with introduction of good optics, video equipment, and appropriate instrumentation general surgeons started exploring new vistas of minimally invasive surgery in an attempt to minimize the trauma associated with their surgical procedures. This approach soon started changing face of a few surgeries like cholecystectomy, Nissan fundoplication, and adrenalectomy. However, as the technology was applied to a wider set of procedures, the pioneers in the field were faced with a new set of problems. These problems made advanced minimally invasive surgery involving fine dissection and major reconstruction difficult to perform and teach.,
Lack of hand eye coordination - The endoscope forces the surgeon to work while looking at a video monitor rather than his hands. This disrupts the hand eye coordination.
Lacks of depth perception - Conventional endoscopes provide two-dimensional vision rather than the binocular vision. This leads to loss of depth perception. The laparoscopic surgeon has to work with help of indirect cues like sizes, shadows, and relative image movements. This is a source of inaccuracies and difficulties while performing fine dissection or reconstruction.
Counter-intuitive movements of the instruments - The instruments are introduced through ports in the body. These ports act as pivots causing the instrument tips to move in opposite direction of the movement of the surgeon's hands.
Amplification of hand tremors - The long and rigid instruments used to amplify the movements and tremors of surgeon's hand, as the hands are closer to the fulcrum formed by the ports as compared to the tip of the instruments.
Limited degree of freedom (DOF) of movements - The port in the body wall constrains instrument motion in two directions so conventional laparoscopic instruments have four DOF-insertion, roll, pitch (up-down), and yaw (side to side). In contrast the open surgeon is used to seven DOF (three at shoulder and wrist each and one at elbow), permitting a great degree of dexterity, and precision for handheld tools. Only four DOF of laparoscopic instrument severely restrict surgeon's ability to perform complex dissection and suturing.
Surgeon fatigue - The laparoscopic surgery requires fine and precise movements in confined workspace with all the limitations mentioned above and the surgeon's position is more often not ergonomic. These surgeries can be prolonged and tiring. Surgeon fatigue impairs the performance making the difficult procedures even more difficult.
The pioneers in the minimally invasive surgery were struggling to overcome the seemingly insurmountable difficulties mentioned as above they were met with a mix of success and failure. At the time the initial enthusiasm to perform every open surgery with endoscopic techniques was waning, defense advanced research project administration (DAPRA) was funding tele-surgical projects in various centers in USA. They sought a system that would enable surgeons at a remote hospital to operate on troops injured on the battlefield. The sites involved in these projects included Stanford Research Institute (SRI), Massachusetts Institute of technology (MIT), IBM's Watson laboratory, NASA's jet propulsion laboratory (JPL) and computer motion.
Automated endoscope system for optimal positioning (AESOP) from computer motion (Goleta, CA) was the first surgical robot to get food and drug administration (FDA) approval for clinical use in 1993. The AESOP system is a six DOF-robotic arm that mimics form and function of human arm to position an endoscope. The arm can be controlled by either a foot pedal; hand control; or voice command. Computer Motion now ships forth generation AESOP HERMES-ReadyTM robotic system. This integrates with their HERMESTM voice control center. This allows the surgeon to voice control the endoscope and peripheral devices like surgical lights, operating table, and archival equipments (VCR, Printers, etc.). Kavoussi and coworkers  have demonstrated that robotic device is more accurate and effective in positioning camera than a human assistant. They also found that inclusion of a robot did not increase operative, setup or breakdown times. The robotic camera holder has become an integral part of many operating rooms performing advanced laparoscopic surgery.
Stanford Research Institute (SRI, Stanford, CA) developed a tele-presence surgical system for open surgical procedures. This system combined advances in remote manipulations with basic force feedback, stereoscopic imaging, multimodal sensory feedback, and ergonomic design. Intuitive SurgicalTM (Mountain View, CA) was founded in 1995. They licensed technology and hired engineers from SRI, MIT, and IBM. The first prototype was built in 1996 for animal trials. This system had two arms with wristed instruments with six DOF inside body and a third camera arm providing stereoscopic vision. Second prototype was tested on humans in Belgium in 1997. The alpha prototype of daVinci SystemTM was used for cardiac procedures in Paris (France) and Leipzig (Germany). The FDA trials for laparoscopic use of daVinciTM were conducted in Mexico City (Mexico) in 1998. daVinciTM Surgical System got FDA approval for laparoscopic use in 2000 and for thoracoscopic use in 2001. By the time of this writing 150 daVinciTM systems have been installed all over the world.
Computer Motion introduced its prototype Zeus Telepresence Surgery System in 1996. This system also consisted of a camera positioning arm and two instrument arms operating laparoscopic instruments, similar to conventional rigid instruments. The system's evaluation for coronary artery bypass grafting in a dry lab was reported in 1997. Margrossian and Colleagues used the system successfully for laparoscopic uterine horn anastomosis in six pigs. In a limited FDA approved trial, 10 patients underwent microsurgical tubal anastomosis. Currently, computer motion is conducting FDA approved clinical trials in laparoscopic, thoracoscopic, and cardiac applications.
The mainstream surgical robots
Two surgical robots are currently available for clinical applications the daVinciTM Surgical System (Intuitive Surgicals, Sunnyvale, CA) and ZeusTM Robotic Surgical System (Computer Motion, Altlanta, GA). Both the systems have some similarities in their designs. They consist of following three basic parts.
Surgeon's console is the user interface of these robots and consists of
1.Display system - a 2D or stereoscopic display system.
2.Master arms or surgeons handles - the surgeon moves the masters, the movements are translated in real time into movements of instrument tips, the slaves. The masters also provide a force feedback to the operating surgeon's hands. In daVinci the masters can be made to control camera movements by pressing a foot paddle. Zeus system incorporates a HermesTM voice control system for camera movements.
3.Control panel - permits surgeon to choose and adjust various display and control options.
4.CPU or the controller - high capacity computer controlling and counterchecking performance of the machine.
Robotic arms, two surgical manipulators and one camera arm. The surgical manipulators drive the instruments and camera arm holds and moves the telescope and camera unit. The arms may be mounted on a cart (daVinci) or on the operating table (Zeus). The camera arm of Zeus is essentially an AESOP robot voice controlled by the surgeon.
Auxiliary or vision cart, containing light sources, camera control units, camera signal synchronizers, and monitors for patient side assistants.
These systems have incorporated mechanisms to overcome the difficulties encountered by the minimally invasive surgeons.
In daVinci the display system projects the image in the direction of the surgeons hands via a mirror overlay optical system restoring hand eye coordination. Zeus system has a high definition monitor at the eye level in front of the surgeon.
DaVinci System has two separate optical channels. The telescope is a combination two 5 mm scopes enclosed side by side in an 11 mm sheath, one scope for each eye's vision. The camera mounted atop these this telescope has two independent three chip CCDs that delivers pictures with 800 lines of resolution. These images are displayed on two cathode ray tube monitors, each displaying slightly different image to each eye giving a 3D vision with a wide stereo separation. The initial models of Zeus were shipped with 2D display but recent model is 3D capable.
The CPU or the controller translates the movements of masters by surgeon in an intuitive way, i.e., movement of master to right is translated to movement of the slave instrument to the right. All the time this is happening, the movements and positions of slaves and masters are being checked and correlated in x , y and z -axis at more than 1000 times per second. The immense processing power of the controller also bring the visual and robotic frame of reference into precise registration giving surgeon a sense of immersion in the work. The force feedback lets surgeon feel large contact interactions and indicates robots workspace limits. The controller also permits the advanced features like clutching (indexing) between masters and slaves, smooth control at workspace limits, and gravity compensation.
Tremor eliminating algorithms are incorporated in both surgical robots. They filter out the natural hand tremors of the surgeon. The movements can be scaled down from 1 : 1 to 3 : 1, i.e., three-inch movement at the master is translated into one-inch movement at the instrument tip. Tremor filtering and scaling down of movements, coupled with the 12-15 magnification offered by the display systems bring unprecedented precision at the minimally invasive surgeon's hand.
Seven degree of freedom movements
DaVinci System's slave arms with articulated instrument tips (EndowristTM) provide seven DOF movements like human wrist. The slave arms provide outer pitch, outer yaw, roll, and insertion movements, while the articulated tips provide inner pitch, inner yaw, and grip. The initial Zeus systems had nonarticulating tip instruments (micro-assistTM). The recent models have instruments with articulating tips (micro-jointTM).
The surgeon consoles in both the systems are ergonomically designed. Operating surgeon does not scrub and performs whole surgery while sitting comfortably on the console. This eliminates limitations posed by physical fatigue to a conventional laparoscopic surgeon.
DaVinci vs Zeus
Despite the basic similarities the two systems are based on widely disparate technologies. From a users point of view they provide various strengths and weaknesses to the systems.
Proprietary vs open system architecture
DaVinci system is based on a proprietary architecture, i.e., it is component subsystems are custom made by other vendors or developed and made in-house by Intuitive Surgical. This provides unparaleled system integration and quality control over the components by the vendor. This approach also increases the initial and maintenance costs as compared to incorporation of 'off the shelf' component systems.
Computer Motion has used open system architecture design for their Zeus system. The system is compatible with any existing 2D or 3D visualization equipment and uses a variety of disposable and reusable instruments from their partner vendors. The company claims that this provides modularity and easy up-gradability.
Total immersion vs or compatibility
In daVinci System, the surgeon sitting on console gets the impression of being completely immersed in the endoscopic operative field without any external bearings or visual cues whatsoever. This helps achieving the intuitive hand-eye coordination and superb depth perception during tissue handling and suturing.
Zeus system enables the surgeon to operate in conventional operating room environment. This facilitates the surgeon to patient side assistant communication.
'Cable - pulley driven' vs 'push and pull rod' instruments
EndowristTM instruments of daVinci are driven by cable - pulley mechanism. This gives an excellent range of movement to the articulating tips. The size of the instruments because of this mechanism is larger and they require 8 mm ports. At Vattikuti Urology Institute, we have performed 130 robotic prostatectomies with daVinci system. We do not perform fascial closure of the robotic instrument ports. We have not experienced any robotic port related complication.
Zeus system employs push and pull rod mechanisms like conventional laparoscopic instruments to drive its instrument tips. This has enabled them to make 3 and 5 mm instruments at the cost of movement of articulated tips. One possible advantage of these instruments is ease of cleaning and sterilization of the instruments.
Cart vs table mounted arms
DaVinci system has cart mounted robotic arms. These arms are attached to the cart through a series of passive setup joints. This arrangement provides great flexibility in positioning the robotic arms around the patient for various procedures. But once the robot is docked to the patient the operating table position cannot be changed without undocking. The cart also occupies important operating room floor space.
Zeus system's three arms are transferred from their individual storage carts to the operating table. Once attached to the table they move with the operating table making changing operating table position possible even during ongoing surgery.
There has been no clinical study directly comparing both robotic systems. The only experimental study which has directly compared the two systems involved performing nephrectomy, adrenalectomy, and pyeloplaty on swine model, concluded that urologic laparoscopic procedures can be performed effectively using either the daVinci Robotic System or the Zeus Robotic Surgical System. The learning curve and operative time were shorter and the intraoperative technical movements appeared more inherently intuitive with the daVinci System.
Development at Vattikuti Urology Institute
At Vattikuti Urology Institute, we have added a 3D projection module to our daVinci System. Vattikuti Institute stereoscopic display for audience, recording, and transmission (VISDART), enables us to display the stereo-laparoscopic image to the assistants and others in the operating room. We can also record, edit, and display recording in 3D. The stereoscopic recordings of our Vattikuti institute prostatectomy have been demonstrated in many conferences (including annual meetings of American Urological Association 2002, 2003 and British Association of Urological Surgeons 2003). The VISDART also permits us to transmit 3D images over traditional television waves. This technology has been used in our workshops to demonstrate live surgery to audiences in conference centers miles away from the operating rooms.
Working with the vendor (Intuitive Surgicals, Sunnyvale, CA), we have modified and tested many robotic instruments for urological applications. Permanent monopolar hook cautery, permanent monopolar scalpel cautery, and bipolar grasper cautery are results of this collaborative effort.
Surgical robots in laparoscopic urology
Automated endoscope system for optimal positioning camera holder has been used to assist a variety of laparoscopic urologic procedures including, nephrectomy, pyeloplasty, retroperitoneal, and pelvic lymph node dissections, and bladder neck suspension. Guillonneau and associates have used AESOP in over 1000 laparoscopic radical prostatectomy at Montsouris Institute. We have used AESOP with HERMES voice control in 46 out of 48 laparoscopic radical prostatectomies performed at Vattikuti Urology Institute. We had initial problems with voice recognition. But once the voice cards were reprogrammed for the surgeons' voice, the system worked with great reliability.
The first use of robotic manipulators in urologic procedure to perform a surgical procedure is by Bowersox and Cornum. They used SRIs prototype telesurgical manipulator for open surgery and performed nephrectomy, cystotomy closures, and ureteral anastomosis.
Sung and coworkers randomized five females swines (10 kidneys) to undergo conventional laparoscopic pyeloplasty (four procedures) and robot assisted laparoscopic pyeloplasty (six procedures using Zeus robotic system). They concluded that robotic suturing was associated with a short learning curve. They also demonstrated the feasibility of performing the entire procedure robotically with watertight anastomosis. The same group compared conventional laparoscopic nephrectomy and adrenalectomy with robotic procedures with Zeus system. The robotic procedures took longer operative time (2.7 times for nephrectomy and twice for adrenalectomy) but were comparable in blood loss, dissection, and suture ties.
The first reported robotic assisted laparoscopic urology procedure on humans is radical prostatectomy by Abbou and coworkers in 2000. They used a daVinci system. Since then several other groups have published small case series (Rassweiler et al., six cases; Binder et al., 10 cases; Pasticier et al., five cases) of laparoscopic prostatectomies performed with daVinci robotic assistance.
Guillonneau et al. (2001) reported a comparison of robot assisted and laparoscopic pelvic lymphadenectomy using a Zeus system. They had a significantly higher mean operating time for robotic group (125 min V/s 60 min). The histopathological results in terms of lymph nodes removed were comparable. Guillonneau et al. also reported a nephrectomy performed by Zeus system.
At Vattikuti Urology Institute, we have one of the largest experience with robot assisted radical prostatectomy. We use a daVinci System and by the time of this writing have performed 560 robotic prostatectomy procedures using Vattikuti Institute prostatectomy technique. Using a structured approach for the development of the program, we were successful in bringing down operative times; our blood loss and positive surgical margins are comparable to the best in reported literature for laparoscopic prostatectomy.
The surgical robots, with increasing computing power, miniaturization, and advances in telecommunication, will become more versatile and affordable. We have recently tested prototypes of 5 mm instruments and an auxiliary arm of daVinci system. The instruments with smaller diameter will make this system useful in pediatric procedure. Addition the auxiliary arm will eliminate need of a patient side surgeon in most of the procedures. Similarly industry is working on the development of instrumentation for suction, retraction, and hemostasis with these robots. There are plans to develop surgical robots which are MR compatible, giving advantage of real time MR imaging to the surgeon while operating with the robot.
The Genie is out of bottle; the surgical robots have reached a level of reliability and precision. The urologist community has to make use of the precision and flexibility offered by these modern marvels in a judicious way to complex minimally invasive procedures.
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