Telemedicine and Surgical Robotics: Urologic Applications

Techniques & Technology

TECHNIQUES & TECHNOLOGY Telemedicine and Surgical Robotics: Urologic Applications Benjamin R. Lee, MD* Jeffrey A. Cadeddu, MD† Dan Stoianovici, PhD† Louis R. Kavoussi, MD† *Johns Hopkins-Singapore Clinical Research Centre National University of Singapore Singapore James Buchanan Brady Urological Institute Johns Hopkins Medical Institutions Baltimore † Medical treatment can be improved through integration and application of advances in technology, computers, and engineering. Accuracy and reliability are essential characteristics of any mechanical system, and with the evolution of machines capable of precise movements, the integration of medicine and machine is achievable. Early mechanical devices were effective in performing simple, repetitive tasks but were not sophisticated enough for independent function. In the automobile industry, robots could work on the assembly line executing these cyclic tasks. These machines could execute simple, reiterative movements without integrating new information from the environment. In this day and age, robots have evolved into sophisticated mechanical devices that can “react” to data detected in the environment to determine the next course of events. They have evolved from the assembly line to the operating room, assisting surgeons during surgery to participating in remote telesurgical procedures. [Rev Urol 1(2):104-110, 120, 1999] Key words: Telemedicine • Robotics • Percutaneous access O ver the past half century, robots have been used in industry, diving exploration, and outer space. With the ability to improve efficiency without the cost of extended treatment time, medical researchers have begun to develop application of robots into the realm of health care. Four areas in the realm of health care have been investigated: hospital ancillary support, laboratory medicine, rehabilitative medicine, and surgery. Robots as hospital ancillary support have helped deliver patient meals, medications, and x-rays to specified areas of the hospital (Help-Mate, Transitions Research Corporation, Milford, Conn).1 The navigation system of this robot uses motion sensors to prevent collisions while tracking itself within a hospital blueprint. Assisting people with physical disabilities is another area for which robots have been developed. Typical devices include robotic arms that aid the patient with eating or tool manipulation 104 REVIEWS IN UROLOGY SPRING 1999 Telemedicine as well as devices that help with automated locomotion.2,3 In the 1980s, the application of robots in surgery was pioneered by neurosurgeons4-6 and orthopedic surgeons.7 The principle of registration, ie, calculating spatial coordinates of the target organ for presurgical planning to map the robotic movements, is easily overcome in these fields due to relatively fixed target organs. Three types of devices—neuronavigators, stereotactic localizers, and robotic assistants—have been developed in neurosurgery to improve spatial accuracy and surgical precision within the skull. In orthopedic surgery, robots have been developed capable of carving and preparing a human femur for artificial hip replacement. The RoboDoc system (Integrated Surgical Systems, Inc, Sacramento, Calif) cuts a cavity 10 times more accurate than manual reaming, with an accuracy of 0.5 to 1.0 mm. Based on the success of robots in these surgical specialties, the investigation of robots in urology commenced. Robotic devices to assist urologists with laparoscopy, percutaneous access to the kidney, transurethral resection of the prostate, and prostate biopsy are currently in development or already in clinical use.8-16 Cutting-edge telemedicine and virtual reality applications have also integrated robotic technology and are presently being incorporated into urologic applications. The urologist of the 21st century should become familiar with this new interdisciplinary field, its basic principles and technology. This article will review current urologic robot applications and research. Definitions A robot is a combined mechanical, electronic, and computer system that follows a simple cycle of commands and task execution for operation.12 First, the computer learns environmental information from its sensors. Based on this information and the task to be accomplished, computer algorithms calculate appropriate commands for the motors. These commands are sent to the mechanical system, which executes the task, and the cycle repeats. Apart from giving the surgical robot commands to be carried out via a sequence, all actions of the robot have to be continually monitored to correct deviations from the planned trajectory. There are several basic terms essential to the understanding of robotic function (Fig. 1). The basic configuration encountered in medical applications is an armlike device called a manipulator. The range of motion of each manipulator is called its working envelope. The manipulator is normally connected to a base (floor, ceiling, operating table, etc) and composed of a succession of joints and links (appendages). The instrument with which the robot performs the desired task is attached to the last link of the arm and is referred to as the endeffector. In surgical robots, an endeffector can be a needle, grasper, scalpel, or even a resectoscope. All complex joint movements may be simplified down to 2 elementary motions: rotational (R) and translational (T). The number of these elementary motions at a joint is defined by the term degree of freedom (dof). For example, the piston of a syringe has 1T dof, and the human shoulder and wrist have 3R dof each. By definition, the dof of a robot is the dof summation of all its joints. This conveys the motion abilities of the endeffector. For example, the robot in Figure 1 has 6 dof (4R and 2T), while the human palm has 7 dof (3 shoulder + 1 elbow + 3 wrist). At least 6 dof are required for complete freedom of motion of an end-effector. If a joint is driven by a motor, it is called active; if not, then it’s called passive. An entire system can therefore be passive (eg, stereotactic localizers), active (eg, RoboDoc), or a com- Figure 1. Robotic terminology: A robot is a combined mechanical, electronic, and computer system capable of performing complex tasks. R, rotational; T, translational. Reprinted with permission from the American Urological Association. 45 bination of both (eg, AESOP— Automated Endoscope System for Optimal Position, Computer Motion Inc, Goleta, Calif). Robots are also equipped with sensors and actuators. Sensors measure the spatial position of joints but can also provide other information such as joint velocity, acceleration, and torque. Mechanical motors are also called actuators and are connected to each active joint of the manipulator. Therefore, a robot has as many motors as active joints. The more common type of actuator is electric, but hydraulic, pneumatic, or nonconventional piezoelectric or memory-shape alloy designs may also be used. Finally, many robotic systems in medicine utilize imaging technology to position, guide (track), and monitor the robot as it performs the task.16 Fluoroscopy, computed axial tomography, ultrasound, or magnetic resonance imaging may be used. Since most imagers provide 2-dimensional (2D) images, the robot must obtain 3D coordinates of the anatomic target from multiple 3D images using the principle of triangulation. The robot must continually “know” where it is relative to a patient’s anatomy. This process requires mathematical correlation (mapping) of the image with SPRING 1999 REVIEWS IN UROLOGY 105 Telemedicine continued relative and absolute reference points called registration. Current State of Urologic Robots Issues such as safety, accuracy, sterilization, compactness, compatibility with medical imaging devices, and ergonomics must be addressed prior to clinical application of robots. Research and development involve a laborious cycle of testing and reevaluation with experiments and testing in the laboratory prior to clinical application. Although these difficulties delayed urologic robotic development until the late 1980s, recent innovative research has resulted in several projects designed specifically for urologic application. Furthermore, robotic assistants developed for general surgical applications have also found a role in urology. This section outlines several robotic research efforts, in various stages of development, in the areas of laparoscopy, telesurgery, percutaneous renal ac- cess, prostate biopsy, and surgical planning. Laparoscopic Surgery. The increasing presence of laparoscopy in urology has led to the development of several devices to assist the surgeon.17-22 These devices have consisted primarily of manipulator arms that position the endoscope or laparoscopic instruments. Several passive mechanical devices have been developed (ie, Leonard Arm, Leonard Medical, Inc, Huntingdon Valley, Pa). The main benefit of these arms is to reduce the distractions to the operating surgeon by eliminating inadvertent and disorienting movements of a human assistant. While these passive devices are simple and cost-effective, they require the surgeon to release the surgical instruments to reposition the laparoscope. To address this issue and allow the surgeon to keep his or her hands on the surgical instruments, several robots have been developed to active- Figure 2. Haptic telepresence feedback system uses multiple robotics. 106 REVIEWS IN UROLOGY SPRING 1999 ly move the laparoscope and assist the surgeon. Taylor and colleagues developed the LARS robot,18 a 7-dof device that holds and pivots the laparoscope about the point where it enters the abdominal wall. Though used in several experimental settings, this system has not been used clinically. Begin and coworkers have modified a commercially available A460 industrial robotic arm (CRS Plus Company, Toronto, Canada) to successfully hold and move the laparoscope during cholecystectomies. Although this system was clinically successful, it was limited by safety concerns. The first robot to receive FDA approval, AESOP, has been used clinically at several institutions. AESOP is a 6-dof robot that attaches to the operating table and is controlled by either a foot pedal, hand controller, or voice commands. There are 2 important safety features: 2 passive joints that prevent any lateral forces from Telemedicine being applied to the abdominal wall, and a magnetic collar that automatically separates the laparoscope from the robot if the applied force is greater than 7 lb. The next generation of AESOP will have an additional degree of freedom to allow optimal positioning. Clinical experiments with this device have demonstrated steadier laparoscopic camera positioning. AESOP has assisted in a variety of laparoscopic urologic procedures, including nephrectomy, pyeloplasty, retroperitoneal and pelvic lymph node dissections, and bladder neck suspension. Partin et al expanded its utility by using a second robot to hold retraction instruments and thereby perform single-surgeon laparoscopy with no human assistance.20 Previous concerns that utilization of AESOP would increase operating room setup time and, therefore, expenses were addressed by Kavoussi et al who determined that neither operative setup nor breakdown time was increased with the use of a robotic assistant.22 In fact, robotic surgical assistants may be more economical than human assistants for laparoscopic surgery. Further attempts to improve laparoscopic assistant devices have focused on increasing dexterity and providing force feedback to the surgeon.23 DAUM GhbH of Germany has developed a 3-fingered, wrist articulated, 7-dof miniature laparoscopic hand (EndoHand) to potentially increase dexterity. Two models of this device exist. One is cable operated from a special glovelike device worn by the surgeon while the other uses the same miniature hand but is actively controlled by a data glove in master-slave architecture. The latter design allows for telesurgical operation of the minihand. The system has not been tested clinically, but in vitro experiments comparing it with current laparoscopic instruments have been performed. The device falls short in both dexterity and tactile Figure 3. Percutaneous Access to the KidneY with Remote Center of Motion, PAKY-RCM. The system uses a robotic needle positioner and needle driver that employs a novel principle—friction transmission with axial loading. Adapted with permission from the American Urological Association.45 feedback, but it shows significant promise in its ability to perform sophisticated manipulation of objects and to work at a larger range of angles to the target tissue. The results of clinical trials will further determine its eventual usefulness in laparoscopic surgery. Teleoperation, Telementoring, Telesurgery, Telepresence With advances in telecommunication and computer technology, telesurgical applications in urology are now being evaluated.24-26 Having demonstrated the utility of a robotic arm for laparoscopic procedures, we have also explored its use in telerobotic surgery for telementoring purposes. The current system incorporates bidirectional video and audio communication, telestration, electrocautery remote activation, x-ray image transfer, and remote control of the AESOP robot. Using this system, an experienced laparoscopic surgeon at a remote site can teleoperate the robotic arm to position the laparoscope, activate the electrocautery to stop blood vessels from bleeding, and guide the primary surgeon through a procedure. The main benefit of such a system would be as an educational device to convey the experience of a surgeon well-versed in the procedure (mentor) to a second surgeon (student) at a remote location. The first generation of this telesurgical system was operated remotely within the same hospital. The second generation moved the remote site to a different institution, 3.5 miles away, and a single high-bandwidth telephone line (T1, 1.54 Mbps, 17 times as fast as a regular phone line) was used for communication. Complex laparoscopic procedures such as bladder augmentation and partial nephrectomy were accomplished successfully utilizing this system. In all cases, the procedures were completed without intraoperative or postoperative complication. The third generation involved laparoscopic telesurgery on an international scope. The initial success with international telesurgery has allowed procedures to be performed in Bangkok, Thailand; Innsbruck, Austria; Rome, Italy; and Singapore. Recently, a series of 6 telesurgical procedures were performed between the United States and Singapore to demonstrate the feasibility of international telementoring and telerobotic procedures. Telementoring as an educational tool was able to be conducted from the United States to Singapore and from Singapore to the United States. Basic procedures, such as a laparo- SPRING 1999 REVIEWS IN UROLOGY 107 Telemedicine continued scopic varicocelectomy, were performed as well as a complex procedure—a laparoscopic nephrectomy. A telepresence prototype for open surgical procedures funded by the Defense Advanced Research Projects Agency has been developed at the Stanford Research Institute (Menlo Park, Calif), having evolved from initial work by Green et al.27 The SRI telepresence principle or “Green Telepresence System” is based on a master-slave relationship of two 7dof manipulators (6 dof arm plus 1 dof gripper) that parallels the surgeon’s movements and transmits the forces of the end-effector back to the grips the surgeon is holding. Threedimensional video and audio help immerse the remote surgeon into the operating field. An additional benefit is the ability to magnify the scale of movement of the surgeon’s hands to the robot’s actions, thereby facilitating microsurgical tasks of suturing, microdissection, and incisions. This robot can also be used in open surgery. Cornum and colleagues have reported successful in vivo porcine nephrectomies and repairs of bladder and ureteral injuries.28 A second haptic feedback telepresence system, Zeus, has been developed for remote laparoscopic surgery by Computer Motion, Inc. Zeus consists of 3 modified AESOP robots, 1 for the laparoscope and 2 for the instruments, and a purpose-built bilateral haptic interface, with handles similar to those of conventional laparoscopic instruments (Fig. 2). Though a surgical assistant is required to position the robots and laparoscopic ports locally, the surgeon operates the system from the remotely located haptic interface. As the surgeon moves the haptic handles, the robotic manipulators in the operating room move in a similar fashion while concurrently, force feedback is returned to the surgeon.29 To date, this system has been used successfully to perform ex vivo procedures. Percutaneous Renal Access Percutaneous renal access is another procedure in urology that depends greatly on the surgeon’s experience and technique. Obtaining access in the operating room can be challenging using only C-arm fluoroscopic guidance. Several groups have developed robotic systems to assist the urologist with intraoperative percutaneous renal access.30 The Imperial College of London employed a passive 5-dof manipulator equipped with electromagnetic brakes mounted on the operating table. The access needle was manually positioned as instructed by a computer that triangulated the calyx location from multiple Carm x-rays. Initial in vitro experiments demonstrated a targeting accuracy of less than 1.5 mm.31 In vivo experiments have not been performed to date. Similarly, the robotics group at Johns Hopkins Medical Institutions developed an experimental system to gain percutaneous renal access.32 This system differed from the earlier Imperial College system in that it employed an active robot to manipulate the access needle and a biplanar fluoroscopic imaging system. The surgeon chose the target calyx in 2 biplanar images, after which the robot positioned the needle and injected it into the desired location. In vitro performance experiments demonstrated an impressive accuracy of less than 1.0 mm. Furthermore, using ex-vivo porcine kidneys with contrast-filled collecting systems, the system successfully accessed the targeted calyx on the first attempt 83% of the time. Recently, porcine cadaveric and live percutaneous renal access experiments were completed using this system. The success rate of placing a needle into the target calyx on the first attempt in these models was 50%. Problems encountered were related to kidney displacement by needle insertion, needle deflection or bowing, and rib inter- 108 REVIEWS IN UROLOGY SPRING 1999 ference. Nevertheless, this system demonstrated that a fully automated robotic system for soft tissue needle placement is feasible. Recently, a system that parallels and improves upon the surgeon’s standard technique has been developed. Rather than automating registration of the target calyx, ie, positioning of the needle and solving complicated image distortion and registration problems, Stoianovici and colleagues opted for a simple alternative that allowed immediate surgical use and utilized the C-arm fluoroscopy x-ray available in the operating room. The system was based on an active radiolucent needle driver, PAKY (Percutaneous Access to the KidneY) that employs a novel kinematic principle—friction transmission with axial loading (Fig. 3).33-35 Instead of pushing the needle from behind, this injector holds the barrel of the needle along the side, thereby reducing the unsupported needle length during insertion and minimizing needle deflection. PAKY itself was mounted on a passive arm connected to the operating table and was positioned such that, under fluoroscopy, the needle appeared as a single point superimposed over the target calyx. The supporting arm was then locked, allowing the surgeon to rotate the C-arm to a lateral view, gain depth perception by triangulation, and advance the needle under continuous fluoroscopic imaging using a joystick. The procedure simplified and improved the safety and accuracy of the manual technique in that needle deflection and depth could be monitored continuously while minimizing the surgeon’s radiation exposure. Surgical trials using PAKY have recently commenced. The new robotic system was successful at obtaining percutaneous access in 9 of 10 kidneys.36 For successful procedures, the mean time to gain access was 16 minutes, with a mean of 3 attempts Telemedicine or passes with the needle to obtain entry into the collecting system. The average width of the target calyx was 11 mm. There was 1 failure in a patient with a partial staghorn calculus filling the lower pole of the kidney. After PAKY was abandoned in this patient, access time was greater than 45 minutes using standard manual techniques. Difficulty in this kidney was attributed to the tight filling of the collecting system with the stone. There were no complications or difficulties caused by the robotic system. Any increase in operating room setup time was negligible, as PAKY was mounted and covered with a sterile bag during patient positioning and sterile preparation. In every case, there were no perioperative complications attributable to the use of the device. In an attempt to automate PAKY’s positioning, a low dof, miniature robot is also under development to replace the passive arm, RCM (Remote Center of Motion). This robot has an extremely low profile, making it compatible with portable x-ray units and computed tomography scanners. The new system (including PAKY) exhibits 3 motorized dof: 1 translational, to insert the needle, and 2 rotational for needle orientation. These 3 dof are sufficient for accessing any anatomic target after the skin insertion site is set. The minimal dof of this design also increases patient safety. The system will improve needle placement accuracy and procedure times while again reducing the radiation exposure to the patient and the urologist.37 A third modification was performed to add a telecommunications interface and allow remote active positioning and insertion into the kidney. On June 17, 1998, the first remote telerobotic percutaneous renal access procedure was performed over 4,500 miles between Baltimore and Rome, Italy (Fig. 4). This new telesurgical robot was successful at obtain- Figure 4. Remote telesurgery. On June 17, 1998, the first remote telerobotic percutaneous renal access procedure was performed over 4,500 miles between Baltimore and Rome, Italy. Adapted with permission from the American Urological Association.45 ing percutaneous access within 20 minutes, with 2 attempts to obtain entry into the collecting system. On the first attempt, inadequate orientation of the fluoroscopic unit resulted in failed access. On the second attempt, successful delivery of the percutaneous needle was confirmed with return of urine, passage of a wire into the collecting system, and an antegrade nephrostogram. Transurethral Prostatectomy Transurethral resection of the prostate (TURP) gave rise to the first urological robot in 1989.38-40 The fixed position of the prostate relative to the pelvis and the fact that a TURP procedure required repetitive movements in a specific geometric pattern made the robot a good candidate for performing this operation. Prior to clinical testing of the robot, safety issues were addressed by performing manual TURP within a special safety frame—designed to physically limit the robot’s resection to a restricted volume—that was placed over the patient’s perineum. Thirty patients with bladder outflow obstruction and flow rates less than 15 mL/sec underwent TURP with the safety frame in place and the resectoscope operated by the surgeon. At 1-year follow-up, the preoperative flow rates improved from 10 mL/sec to 22 mL/sec in this group, a result comparable to conventional TURP. Having demonstrated successful use of the safety frame, the robot was then designed in the shape of the frame. The system allowed 4 dof such that a separate motor drove each necessary motion, including that of the resectoscope loop. The frame-like robot was attached to the operating room table. Using prostate boundaries defined by transrectal ultrasonography (TRUS),41-42 the surgeon specified the volume to be resected. The motorized frame was then positioned and the resectoscope manually placed at the verumontanum. Automatic resection commenced and was observed under continuous video monitoring. A clinical trial of 5 patients demonstrated that the entire resection could be performed rapidly with hemostasis achieved manually after the final cut. This trial identified the need for modifications, including an alternative to TRUS prostate imaging, because it was found to be insufficiently accurate. Furthermore, registration needed to be reobtained if the patient shifted during the proce- SPRING 1999 REVIEWS IN UROLOGY 109 Telemedicine continued Main Points √ A robot needs at least 6 degrees of freedom (the number of rotational or translational motions at a joint) to have complete freedom of motion in the end-effector, which can be a needle, grasper, scalpel, or even a resectoscope. √ More than 1 robotic assistant can be used during laparoscopy, allowing a single surgeon to perform the procedure. For laparoscopy, robotic assistants may be more economical than human assistants. √ A surgeon experienced in a procedure can become a telementor using robots, instructing surgeons on an international scale. To date, complex precedures, such as laparoscopic nephrectomies, have been accomplished. √ Friction transmission with axial loading allows 1 robotics system to hold the needle barrel along the side to minimize needle deflection. √ Robotic systems that are compatible with portable x-ray units and computed tomography scanners reduce radiation exposure to both patient and urologist. dure, since the landmarks obtained were relative to the operating table, not to the patient. Clinical trials with transurethral ultrasound imaging of the prostate have been designed. demonstrated the advantages of a robotic system, including increased accuracy and reliability, because the robot maintained its position without any drift. Prostate Biopsy Virtual Reality Simulators Another image-guided robotic system that has been evaluated clinically is a robot developed at the Politecnico of Milan, Italy, to perform a transperineal prostate biopsy. Using TRUS, this system demonstrated a needle positioning accuracy of 1 to 2 mm in 3-D space.43 An important technological step in this system design was the automated positioning of the biopsy needle. The surgeon chose the site to biopsy from the TRUS images, and the robot positioned the needle and obtained the sample. In addition to providing important experience with ultrasound-guided robotic technology, this group also explored prostate biopsy as a telesurgical procedure44 (remote control site was 5 km from the operating room) using a single ISDN line. Unfortunately, broad clinical use of this system is unlikely in the near future due to the expense and setup time. Conventional transperineal or transrectal prostate biopsy performed by an experienced urologist is quick, allows digital biopsies of indurated isoechoic areas, and does not require patient anesthesia to prevent movement. Nevertheless, this biopsy robot Flight simulators have long been used successfully to train pilots. Adapting such technology for presurgical planning in medicine and training of critical laparoscopic skills would allow the surgeon to plan the surgical procedures prior to any incision being made. Such a system would decrease risk to the patient, as well as allow the surgeon to “practice” the surgical approach. Furthermore, simulators could be used as an educational tool to decrease training costs while improving surgeon training. With further improvements in computer technology, it is likely that virtual simulators will be used routinely to train surgeons in the 21st century. Urologic simulators already exist. HT Medical, Inc (Rockville, Md) has developed a VR flexible ureteroscope simulator that allows the surgeon to navigate through the collecting system and identify tumors and stones. Researchers at the Laboratory for Human and Machine Haptics, Massachusetts Institute of Technology, are developing a laparoscopic surgical simulator with haptic feedback that can be used to improve surgical skills. The simulator represents an integration of virtual environment simulation technology with a focused training approach. The models convey to the user a tactual feeling of pushing or pulling soft tissues that may represent a more realistic environment to the surgeon in training. Conclusions Though many pioneering discoveries have been made, urologic robotics is still in its infancy. With advances in technology in software, hardware, and telecommunication, the application and utility of surgical robots will only expand. It is imperative that the urologist of the 21st century be familiar with this new interdisciplinary field. 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