From June 1997 Issue

David Allen with Jon Bowersox, M.D. (Telepresence Surgery) and G. Garfield Jones (Telementoring)

Author David Allen is a 4th year medical student at the U. of Kansas Medical Center. This overview is a result of the clinical rotation David did in 1996 with Dr. Bowersox at Stanford Research Institute. David accompanied Dr. Bowersox and sat in the cockpit of the telepresence surgery unit at SRI, reporting, "From the moment I sat down at the console and manipulated the control arms of the system, most movements felt natural. The visual environment was very realistic -- at one point I tried to reach into the empty workstation to adjust placement of an errant needle."

Dr. Jon Bowersox is Director of Trauma Service, Stanford U. School of Medicine, and a pioneer in telepresence surgery (bowersox_j@hosp.stanford.edu)

G. Garfield Jones is Director of Member Services, US TeleMedx Corp., a telemedicine service bureau providing technical, training, telecommunications and clinical support on-line (GarfieldPA@aol.com)

Telesurgery is the provision of surgical care over a distance, with direct, real-time visualization of the operative field. It may be categorized as follows:

1) Telepresence surgery. Uses a computerized interface to transmit the surgeons actions at a surgical workstation to the operative site at the remote surgical unit, with haptic (force feedback) input to transmit to the surgeon the tactile environment of the operative field

2) Telerobotics. Remote control with a robotic arm, usually in conjunction with a laparoscope, without haptic feedback

3) Telementoring. An experienced surgeon acts as a preceptor for a remote inexperienced surgeon by observing the surgeon via interactive video. Teleproctoring is an extension of telementoring, referring to documentation of performance for privileging purposes.

Related fields, such as virtual reality and computer generated educational and training scenarios, will not be discussed.

Telepresence Surgery

Telepresence was spawned in the 1950’s by the atomic energy industry’s unique need for the remote handling of dangerous isotopes. These applications, termed "teleoperation", allowed hazardous materials to be handled safely at a distance while being monitored by television. Modern "telepresence" adds multisensory input that recreates the remote visual, auditory, and tactile environment. This allows the operator to feel physically present at the remote site, in terms of sensory input and the ability to manipulate objects. The perception of distance is erased, and the operator can act effectively in a locally recreated environment that is in fact an illusion.

The Equipment

The prototype telepresence system was developed by electrical engineer Dr. Philip Green at Stanford Research Institute (SRI; Menlo Park, CA). The technology has gone through several generations since the first one-handed model was constructed in 1993. The current two-handed system allows the surgeon to manipulate robotic arms that exactly reproduce the surgeon’s hand motions from the surgical workstation to the remote surgical unit. This is accomplished as the surgeon’s fingers are placed into the rings of actual surgical instruments (SEE PHOTO). However, rather than having normal instrument tips, the rings are directly connected to motors, gears, and belts. These precisely translate the surgeon’s hand and finger motions into digital signals that are transmitted through a computer and telecommunications link to robotic arms at the remote surgical station. The system allows movements similar to those that could be performed by the human hand and arm and moveable elbow -- but with a fused wrist. This range of motion corresponds to 4 degrees of freedom (DOF), or number of ways that a robotic arm can move. Note that the human arm has 7 DOF, the hand over 20 DOF. Current work is directed at increasing the DOF of robotic arms to 7 or more DOF.

There has been talk for years of a "virtual reality glove" that would receive the full tactile range, and project the full manipulative capabilities of, the human hand. There is no evidence that such a device will be encountered in clinical practice in the foreseeable future.

Haptic feedback

The surgeon also receives haptic feedback ("force reflection"; graduated tactile input) back through the robotic arms being manipulated. This feedback is accomplished through small servo motors at the near and remote sites, controlled by complex mathematical algorithms. Simply stated, as resistance is encountered by the motors at the remote surgical unit (e.g., the tip of a suture needle passes into tissue more dense than the initial subcutaneous tissue), electronic signals are instantly fed back to the surgical workstation. These cause the motors in the instrument arms there to recreate the same amount of resistance being encountered in the remote surgical unit, even though the instrument handles the surgeon is controlling are in fact suspended in mid air, attached only to electronic cables.

Visual input

Visual input is stereoscopic and three-dimensional (3-D). Two digital color cameras transmit images at a combined rate of 30 frames/second (15 fps / eye) and can be controlled to zoom and pan into and away from the operative field. The 3-D aspect of visual input requires the surgeon to wear optically treated 3-D glasses. The visual environment in the surgical workstation corresponds exactly to that in the remote surgical suite. This is accomplished by mounting a monitor above the surgeon’s workstation, which projects the images from the remote cameras onto a mirror directly over the surgeon’s hands and control rings. The projected image displays the instrument tips from the remote site just as if they were at the end of the rings in the surgeon’s hands. Image transmission is essentially instantaneous. Data are transmitted at 90 Mbps (although research suggests that 45 Mbps should suffice). Audiovisual information accounts for nearly all of this; only a few Mbps of bandwidth are required for haptic information. Thus, a stable, real-time kinetic environment is recreated. Avoiding lag time in transmission is extremely important. Lag time can lead to vestibulo-ocular disruption and "3-D Vertigo" or "simulator sickness". This is frequently encountered in head-mounted virtual reality displays; over 50% of virtual reality (VR) system users experience dizziness, nausea, or headaches within 20 minutes of donning VR headgear. This has not been a problem in high-bandwidth telepresence surgery.

Movement Scaling

Ultimately, one of the most clinically important refinements of telepresence surgery may be "movement scaling". Using straightforward mathematical and engineering techniques, gross movements can be scaled to control much finer movements at the receiving end. Thus, a 1-cm movement of the surgeon’s finger could translate into a 1-mm movement of the remote instrument tip. This would enable a 10x increase in fine motor control for microvascular and plastic surgery. For example, a future surgeon could "be" inside a vessel, repairing the intima with a nearly microscopic needle and suture material. These could be manipulated to tolerances far beyond the physiologic capability of unaided human hand-eye kinetics. Allied engineering also enables the dampening of hand tremors.

Current and Future Uses

Currently, telepresence surgery is experimental and is not a realistic alternative in a modern hospital. Arteriotomies involving incisions and various suturing techniques have been done successfully on swine; wound closure takes about twice as long as standard on-site techniques. However, the precision of the telepresence and on-site techniques has been the same.

Current telepresence surgery systems have operated intra-enterprise, typically with fewer than 1,000 feet separating the surgeon’s console and the remote surgical unit. Concern has been expressed about time lag introduced by further separation -- not so much from compression delay, which is minimal in these broad-band systems, but by the speed of electricity (the speed of light). Preliminary studies have shown that a transmission delay of 100 msec or more leads to problems with surgical accuracy and precision. This should not be a problem in images transmitted terrestrially across a continent, using microwave or fiberoptic links. It is a potential problem in circumglobal or satellite uplinks, where timeliness of transmission is constrained by distance and the speed of light.

Telepresence surgery may have its earliest clinical impact in management of combat trauma. 90% of combat-related deaths occur from exsanguination in the combat zone, prior to evacuation. Many of these lives could be saved if surgical treatment were available within the first "Golden Hour" of injury. Field exercises have tested the feasibility of military telesurgery, and at least one prototype armored vehicle has been outfitted with telepresence surgery equipment. This highly experimental military deployment is augmenting other combat uses of telemedicine, including digital Personnel Status Monitors for locating soldiers and assessing their vital signs, and store-and-forward and interactive video access to worldwide medical expertise.

Application within the space program is also being considered.

Telementoring

As noted, this is the use of interactive video to provide "looking over the shoulder" expertise by a remote expert to a local surgeon inexperienced in a particular technique. It was first reported in 1965 by Dr. Michael DeBakey, transmitting over broadband satellite. More recent efforts have been at bringing the remote surgical expert more into the operative environment through the incorporation of telerobotics.

Telementoring addresses the serious problems of disseminating new operative and especially minimally invasive surgery (MIS) techniques. Currently, over 90% of cholecystectomies (gall bladder removals) are done laparoscopically, using MIS. Other common MIS procedures are herniorraphies, appendectomy, fundoplications, and arthroscopy. Typical training involves time consuming, expensive on-site coursework with an experienced instructor. Telementoring, especially when augmented by telerobotics, helps eliminate the need for travel and adjusting schedules for training and credentialing.

Early MIS was done under direct observation using mirrors and optical gadgets. Today, it is done using fiberoptic lighting and image acquisition that transmits the image to a video monitor, where the surgeon views the operative field indirectly. Since the image is on video, it can be readily digitized, compressed, and transmitted to a remote viewing station within the institution or miles away. Usually images are transmitted at 384 – 768 Kbps (ºT1 – ‡T1) using the H.320 compression standard. Multipoint conferencing allows participation from multiple sites, so that a single master surgeon can be precepting at several remote sites at once.

Basic telementoring systems at the operative site include: a room camera showing a panoramic view of the patient and the O.R. team, and which can be directed at an X-ray on a viewbox; a patient camera positioned over the patient, usually incorporated into the light gantry above the patient; at least one local monitor; and a wireless lapel microphone. Video mixers allow for split screen viewing (simultaneous internal and external views). Another common feature is telestration (on-screen annotation for teaching). To better assist the trainee, the telementor must have the ability to control the positioning and view of the laparoscopic camera within the patient. This can be done using a remote control robotic arm (Computer Motion, Goleta, CA, www.ComputerMotion.com – see photo). The total cost for setting up an operative suite for telementoring run from $50 - $100,000. Transmission costs for fractional T1 service (385 Kbps) are usually about $60/hour, plus monthly fixed fees.

In 1992 United Medical Network conducted the first compressed video telementoring session; that company has since gone out of business. In the following few years numerous telesurgery demonstrations were done from Doctor’s Hospitals in Columbus, OH (Dr. James Perez), at the American College of Surgeons Annual Meeting (1993), Alliance for Continuing Medical Education Annual Meeting (1994), and from St. Joseph’s Hospital in Towson, MD to Ethicon Endo-Surgery in Cincinnati (1994). The modern era of telementoring began in 1994 when Dr. C.Y. Liu (Chattanooga, TN) conducted the first private telementoring course on advanced gynecologic laparoscopy. In 1995 the Society of American Gastro-Intestinal Endoscopic Surgeons (SAGES) used dial-up, compressed video for telesurgical education at their annual meeting. Another pioneer association has been the Association of Gynecological Laparoscopists (AAGL). Important use and expansion of the technology has been promoted by teams at Johns Hopkins University and Yale University Schools of Medicine, and at the military’s Advanced Research Projects Agency (ARPA). ARPA has done experiments in which a surgeon has actually performed MIS surgical procedures from a distance using a Nintendo-like keypad/joystick apparatus to control cautery, cutting, laser, coagulation, suction etc.

Several medical manufacturers, such as Ethicon Endo-Surgery, U.S. Surgical, Origin, and Circon-ACMI are now using dial-up, compressed video telesurgery at their headquarters to introduce more surgeons to MIS techniques.

While a few studies have documented the efficacy of telementoring techniques (see references at end), at least one professional organization, SAGES, has formally expressed concern about "premature proliferation of such technology before adequate educational, training, ethical and legal issues have been appropriately deliberated and developed." Nevertheless, it is clear that as surgeons strive to perform (and as patients demand) more types of surgery through minimally invasive techniques, telementoring will provide an important route for widening the circle of trained, competent practitioners. Meanwhile, the issues – liability, reimbursement, cross-state licensure -- that confront other telemedicine applications apply as well to telementoring. A special subgroup of the American Trial Lawyers Association deals with laparoscopy litigation cases; it is likely that their purview will extend soon to telesurgical litigation. SAGES will release its "Guidelines for the Surgical Practice of Medicine in Telemedicine" later this summer, addressing telementoring, teleproctoring, credentialing, and privileging.

SUGGESTED READING

Bowersox JC, Shah A, Jensen J, Hill J, Cordts PR. Vascular applications of telepresence surgery: initial feasibility studies in swine. J Vasc Surg 23:281-7, 1996

Green PS, Hill JW, Jensen JF, Shah A. Telepresence surgery. IEEE Engineering in Med and Biol May/June 1995, pp. 324-329

Hiatt JR, Shabot MM, Phillips EH, Haines RF, Grant TL. Telesurgery: acceptability of compressed video for remote surgical proctoring. Arch Surg 131:396-400, 1996

Moore RG, Adams JB, Partin AW, Docimo SG, Kavoussi LR. Telementoring of laparoscopic procedures. Initial clinical experience. Surg Endosc 10:107-110, 1996

Regan EC, Price KR. The frequency of occurrence and severity of side-effects of immersion virtual reality. Aviat Space Environ Med 65:527-30, 1994

Satava RM. Virtual reality and telepresence for military medicine. Comput Biol Med 25:229-236, 1995

PROFILES OF WORKING TELESURGERY PROGRAMS

Telemedical Emergency Neurosurgical Network

Developed by neurosurgeon Paul Chodroff of Walnut Creek, CA, this network links five private practice neurosurgeons at John Muir Medical Center with Sutter Solano Medical Center in Vallejo, which doesn’t have around-the-clock access to neurosurgeons. From home or office computers at 11 locations in the north Bay Area, Chodroff and colleagues can view digitally transmitted CT head scans of patients brought to the Sutter emergency department 30 miles away, and evaluate whether – and how urgently -- they need surgery. Currently 9-10 cases are seen per month; a total of about 300 cases have been seen since program inception in 1994. Nearly 60% have not required transfer. Most of these would otherwise have been transferred via helicopter or ambulance at an average cost of $4,500.

Since CT images are in digital format to begin with, no digitization is required. A video interface to Macintosh computers with boards from MultiAccess Computing expedites image transfer over ISDN at 128 Kbps, using ADTRAN ISU/CSU units. Images are received at Macintosh or PC computers with monitors resolutions of 1024 x 768. An 18-slice CT scan can be transmitted at 2:1 lossless compression in four minutes.

The total cash outlay for the project has been about $43,000; in-kind (pro bono) products and services have been supplied by ADTRAN, CalREN (a Pacific Bell trust), and BPC Consultants, of which Dr. Chodroff is a principal.

Dr. Chodroff emphasizes that this is a telemedicine consultation rather than simply teleradiology. It utilizes simultaneous interactive audio consultation and, as necessary, text and audio files can be appended to the radiographic record. This is especially useful for bundling patient records when soliciting a telemedical "curbside consult." Currently, there is no evidence that interactive videoconferencing capabilities would add much value. To date, there has been no case where a significant difference was noted between the transmitted images and the hard copies sent with patients. The project has been adjudged fully in compliance with COBRA/EMTALA regulations for emergency medical consultations by the regional HCFA Health Care Standards & Quality authority.

This expanding community service project is gradually adding hospitals and neurosurgeons. There are plans to enable MRI scan transmission. Contact Dr. Chodroff at PHC_BPCCons@compuserve.com.

Surgical Tele-Education: The Ross Procedure

Classically, diseased aortic valves have been replaced with artificial or pig valves. These require sometimes hazardous postoperative care such as anticoagulation. A technique developed by Dr. Donald Ross, a London-based cardiothoracic surgeon, repairs the diseased portion of the valve using donor tissue from the patient’s own heart. This highly complex surgery can result in a longer lasting repair requiring less postoperative intervention. However, few cardiothoracic surgeons are trained in the technique. In early May, 1997 a Ross Procedure symposium was held in Indianapolis, chaired by Dr. John Brown, chief cardiothoracic surgeon at Indiana University Medical Center. With Dr. Ross in attendance, Dr. Brown performed three successive Ross Procedures, and was able to demonstrate the technique to colleagues in Denver, CO and at a nearby hotel. Over 80 off-site surgeons were able to observe the surgery with close-up views of the operative field and more panoramic views of the operating theater, projected onto 10x12 foot screens. Moreover, the sessions were interactive, enabling the observers to ask questions of (and give advice to) Dr. Brown in real time. Dr. Brown wore a head-mounted camera intraoperatively, enabling observers to see exactly what he was seeing. The telemedicine equipment was VTEL’s F.R.E.D system, which includes a high resolution 3-CCD camera on an adjustable arm, as well as an integrated PC-based image digitizer/compressor (CODEC), lavaliere microphone, and peripheral devices. The high quality of the projected image prompted Dr. Brown to comment, "Besides the fact that I was the one with the scalpel in hand…there was nothing that I could see that the audience could not."

Live Surgery Education Over the Internet

Another interactive medical training option: live Internet broadcasts of surgical operations. This was done recently when an hour-long cholecystectomy at Wayne State University (Pontiac, MI) was broadcast over the Internet to physicians in the U.S. and Argentina. The project, coordinated by Dr. Alejandro Gandsas, was a feasibility study transmitting images over 28.8 Kbps modems, with image displays of 320x240 pixels. Hardware included 75 MHz Pentium computers with video-capture cards. While image quality and motion handling were far from perfect, they were good enough for observing surgeons to identify pertinent anatomic structures. Also, the interactivity enabled collegiate commentary and advice. Internet interactions have a powerful advantage over satellite or other long-distance options: there are no transmission costs.