Telemedicine-Breaking the Distance Barrier in Health Care Delivery

Telemedicine-Breaking the Distance Barrier in Health Care Delivery

V. Garshnek, Ph.D.; L. H. Hasseff, M.D.; and H. Q. Davis, M.D., M.P.H.; Tripler Regional Medical Center, HI

V. Garshnek, Ph.D., is Project Manager of the AKAMAI Telemedicine Evaluation Initiative at Tripler Regional Medical Center (TRMC), Hawaii. Dr. Garshnek was formerly an Aerospace Physiologist with the U.S. Navy at the Naval Aerospace Medical Institute, Pensacola, Florida; Senior Scientist, Life Sciences Division, NASA Headquarters, Washington, D.C.; and Principal Scientist for Advanced Planning with Lockheed Engineering & Sciences Company, under contract to NASA Ames Research Center, Motfett Field, California.

Colonel 1. H. Hassell is the Principal Project Director of the AKAMAI Telemedicine Evaluation Initiative at TRMC. Colonel Hassell is a physician in the U.S. Army Medical Corps specializing in Nephrology and is Chief of the Department of Clinical Investigation at TRMC.

Lieutenant Colonel H.O. Davis is tile U.S. Army Pacific Regional Medical Command Flight Surgeon located at TRMC. He is a physician in the U.S. Army Medical Corps and a specialist in Aerospace Medicine. Dr. Davis was formerly a researcher with the Department of Behavioral Biology at Walter Reed Army Institute of Research, Washington, D.C., where he completed a fellowship in Medical Research.

In this century, we have witnessed the rapid emergence of technology and, with it, the ability to break significant barriers previously hindering human progress. For example, through advanced aeronautical technology, we have broken the sound barrier and are now able to fly aircraft through Mach velocities. Through rocket propulsion technology we have broken the gravity barrier, enabling humankind to visit the moon, routinely orbit Earth, and claim space flight as a frontier of human destiny. Currently we are standing on the edge of another barrier that is rapidly eroding-the physical distance barrier. Through telecommunications and computer technologies, such capabilities as telepresence, real-time or stored multimedia information transfer, and real-time interactive video enable instantaneous acquisition of knowledge and expertise (whenever and wherever we need them). We have the means and ability to electronically transport the "essence" of who we are -mental, visual, and, in the future, "tactile-to remote destinations without transporting our physical being!

At the present time, nowhere is this distance barrier eroding more rapidly than in medicine. Patients traveling miles to see a specialist for medical consultation, and medical documents and films being physically stored and physically transported are becoming antiquated modes of operation. Medicine now has a powerful fuel behind it enabling it to operate in a more distance-independent manner. This fuel is telemedicine.

Telemedicine has obvious rural applications; however, it can also potentially unite the world through a global health network making it possible to reach developing and third world countries and effectively respond to international disasters. Telemedicine continues to gain importance in manned space efforts and military operations where distance and time place heavy restrictions on patient transport to remote medical expertise. In fact, the basic telemedicine framework was derived from deliberate engineering and technology transfer, much of it from the space and aviation fields.

The aeronautical engineering student of today may well find a future career in the telemedicine field. Telemedicine has grown to encompass satellite technology, telemetry, communications, telepresence, virtual reality, robotics, and creative applications of space/aerospace technologies to medical problems and procedures. The purpose of this paper is to present a brief overview of telemedicine, its strong aerospace technology beginnings, and its emerging future whose success and progress will depend on teams of individuals skilled in engineering, technology transfer, and medicine.

Telemedicine Defined

Telemedicine is the use of modern telecommunications and information technologies to provide health care to individuals when the health care provider and patient are physically separated. Instead of transporting the patient to the site of the expert caregiver, expert knowledge is transported to the health care provider closest to the patient (i.e., move the information not the patient). Telemedicine includes the diagnosis, treatment, and monitoring of patients using systems that allow ready access to expert advice and patient information. It involves a spectrum of technologies. These technologies can include facsimile, medical data transmission, audio-only format (telephone and radio), still images, and full-motion video. Robotics and virtual reality interfaces are being steadily introduced into experimental applications.

The National Aeronautics and Space Administration (NASA) and the Department of Defense (DoD) have had an early and long-standing interest in the development of telemedicine. Transfer of NASA and DoD technology as well as independent efforts driven by the need for specific telemedicine solutions have resulted in numerous applications for a variety of population groups and scenarios:

Worldwide, forward deployed U.S. forces.

Monitoring and consultation of astronauts in space.

Triage and emergency health care response during disasters.

Services to institutionalized populations in homes for the disabled, nursing homes, or jails and penitentiaries.

Monitoring and consultation for hospitalized, ambulatory, and home care patients.

In addition, the possibility of adding telemedicine capability on commercial and military aircraft is gaining interest.

Telemedicine Infrastructure

The telecommunications infrastructure provides the technology to move information electronically between geographically dispersed locations. Participating sites are linked through electronic networks. The telecommunication medium utilized by telemedicine programs is determined in large part by the available local infrastructure. These can include satellite, microwave link, and terrestrial and submarine lines (either twisted copper phone lines or fiber optic cable). Tools specifically designed for ISDN represent an inexpensive, but nevertheless powerful, terrestrial network that is already available in most industrial regions.

The medical systems infrastructure consists of the equipment and processes used to acquire, present, store, and retrieve clinical information and data. Acquisition and presentation technologies include teleconferencing, data digitizing, and display (e.g., remote X-ray, laboratory tests); text processors (e.g., scanners, fax); or image processors (e.g., video cameras, monitors). Data storage and retrieval include storage devices (disks, tape, CD-ROM), along with technology to compress, transmit, and store data.

Telemedicine and the Space Program

NASA has long used telemedicine for its astronauts²and continues to rely on this mode of in-flight medical consultation. More recently NASA has established telemedicine links with former Soviet republics for disaster relief.³A Specifically, the Space Bridge to Armenia/Ufa project provided assistance to persons involved in the 1989 earthquake in Armenia and a major gas explosion in Ufa. This project was the longest running telemedicine disaster relief effort on record. It has technologically and philosophically paved the way for utilizing satellite uplinks and efficiently planned protocols to provide medical care regardless of distance.

The Space Bridge project provided medical consultation 10 several Armenian regional hospitals, linking them via satellite with four American medical centers. The program utilized two-way interactive audio with one-way full motion video transmitted from Armenia to the United States. There were also separate data and fax transmission lines. Consultation was provided in the areas of neurology, orthopedics, psychiatry, infectious disease, and general surgery. In a separate link, consultation was also provided to the Russian town of Ufa, where a gas explosion during this same period of time caused a large number of casualties. Slow-scan black and white video was transmitted from Ufa to one of the Space Bridge sites in Armenia (Yerevan), which provided satellite uplink.⁵Over a 12-week period, the Space Bridge program was used to discuss the cases of 209 patients. According to data reported by Houtchens et al.,³the use of telemedicine was responsible for changes in the management of a large number of patients. For the 189 Armenian patients discussed, diagnoses were changed for 54 patients, new diagnostic studies were recommended for 70 patients, and treatment plans were changed for 47.

Similarly, a Space Bridge to Moscow was used to provide consultations regarding persons injured in the civil insurrection of October 1993. During the attempted coup in the second half of 1993, NASA took advantage of a videoconferencing link in Moscow that was already in place to provide consultation regarding several casualties of small arms fire. This link was part of the U.S./Russian telemedicine Demonstration Project, which consisted of 18 different sessions dedicated to various medical specialties.

Telemedicine has been utilized on many different occasions; however, it has never before been deployed and tested on such a large scale as was demonstrated in the Space Bridge projects. Ferguson, Doarn, and Scott⁶ have surveyed the Space Bridge projects, other NASA telemedicine activities, and various non-NASA telemedicine applications throughout the world. Interested readers are encouraged to consult this particular paper for expanded reading.

Astrotelemedicine

As mentioned, telemedicine is not a new concept to space flight. Since its very beginning, space medicine has utilized communications and information processing technologies. In many aspects the operational boundary conditions in space medicine, such as remoteness, telediagnostics, and biotelemetry are characteristic of telemedicine applications on Earth. Since the 1960s, in parallel, the United States and Russia served as pathfinders in the development of space telemedicine when they developed capabilities for remote medical monitoring and care for astronauts in their human space flight programs, beginning with Mercury and Vostok, through the current Space Shuttle and Mir programs. In general, medical conferences are held between the crew surgeon and crew members, and during extra-vehicular activity, astronauts are constantly monitored via telemetry. This type of medical monitoring has existed for decades. For example, during the Apollo lunar excursions, EKG, heart rate, oxygen consumption, heat production, suit carbon dioxide levels, and other physiological and environmental variables were monitored by a biomedical team at NASA's Mission Control Center at the Johnson Space Center, Houston, Texas. Flight surgeons were on alert to catch potentially dangerous physiological events and intervene at the earliest possible moment.⁷

Currently NASA has in place a training program that would enable astronauts who are not medically trained to be providers of remote telemedicine services (i.e., able to conduct a basic examination for consulting physicians on Earth). Complicating the provision of such services is the fact that the astronauts must learn to perform these tasks in a micro gravity environment. NASA has recently developed the capacity for private medical conferencing from orbiting spacecraft to Earth stations. Prior to this, telemedicine consultations had to be done via radio or video channels that were potentially open to the public. In the current system, the transmitted data are encrypted and transmitted to the Johnson Space Center, via White Sands Missile Base, New Mexico. These one-way (Shuttle to Earth) video and two-way audio signals are received in unscrambled form only by the chief medical officer in Houston, protecting the confidentiality of astronauts and allowing NASA to limit media coverage of medical problems in space.

Development is continuing for telemedicine to support U.S. astronauts aboard the Russian Mir Space Station and the International Space Station at the turn of the century. NASA's first permanent, operational, international space telemedicine system will be established to support NASA's flight surgeons and astronauts training in several locations in Russia, including the Gagarin Cosmonaut Training Center in Star City, the TsUP (Mission Control) at Kalingrad, several sitC5 in Moscow, and the Baikinor Cosmodrome in Kazakhstan. Utilizing NASA's Program Support Communications Network (PSCN), flight surgeons and astronauts in Russia will be able to obtain telemedicine consultations from the NASA Johnson Space Center.⁶

NASA has recently developed and field tested a small and lightweight prototype telemedicine system called a Telemedicine Instrument Pack (TIP) for potential applications in space as well as remote Earth applications.⁸ The TIP resembles a small suitcase and is entirely self-contained. It contains commonly used diagnostic instruments (digital scopes), cameras, and a small flat video monitor. The unit has completed an 8-week field trial on Earth and is scheduled for flight testing in space aboard the Space Shuttle in 1997⁹.

In the future, telemedicine capability will be an important component in space crew health care aboard the international Space Station, especially in the prevention and early intervention aspects of disease and injury. In addition, during a medical emergency, telemedical capability can play an important 'lifeline" role in the rapid exchange of patient information and access to special medical expertise and crucial instruction. However, if an emergency is life threatening and requires medical treatment, the combined resources of telemedicine and existing onboard medical capability may he limited, requiring medical evacuation to Earth. For missions beyond Earth or-bit, evacuation to Earth may not be an option, and the overall onboard medical capability (including expert computer systems and telemedicine capability in the "store and forward" mode) as well as crew medical expertise will need to be greatly enhanced.

Telemedicine and the Military

The United States armed services have long had an interest and involvement in both mobile health and telemedicine services. In fact, some of the most ambitious global applications of telemedicine and utilization of satellite technology can be found in the military. Recent developments in data compression, fiber optics, satellite communications, computer inter-networking, information technology, advanced medical imaging and diagnostics have combined to provide the U.S. military with the ability to establish a world wide integrated health care delivery network. Various combinations of these technologies have been tested in joint exercises, U.S. Army Advanced Warfighting Experiments (AWEs), aboard deployed naval vessels, in the peacetime Military Health System (MHS), and as part of the support for operations in Saudi Arabia, Kuwait, Somalia, Haiti, Cuba, Panama, Croatia, Macedonia, and Bosnia.

Advanced telecommunications technology was used in conjunction with mobile health units during the war in the Persian Guif,'⁰demonstrating that these two technologies can be integrated, even under difficult geographic and climatologic circumstances, with beneficial effect.'' Computerized tomography (CT) scanners were installed in transportable modular military hospital units and deployed in the Saudi desert just south of the Iraqi and Kuwaiti borders.¹⁰

Recently, the U.S. Department of Defense established a medicine network that serves U.S. troops in Bosnia and other countries. The telemedicine segment of this project, known as Operation Primetime Ill, is designed to help Army physicians communicate with each other using real-time voice and video for consultation and diagnosis. The communications network in Bosnia is being supported by an Orion-built communications satellite orbiting over the area, thereby providing direct broadcast capability. Using commercially available technology, front-line physicians can transmit x-rays and other medical images to field hospitals for diagnostic support. These same links, which extend to deployed units and small clinics at forward areas in Bosnia, connect Army physicians in Bosnia with physicians at five regional military medical centers in the U.S. The network also offers online medical information, patient administration systems, and information systems.

Operation Primetime was first established in 1993 to provide telemedicine support to medical units in Macedonia and Croatia. The operation was upgraded to Primetime II in 1995 with a 30-fold increase in communications bandwidth that substantially improved the transmission of medical images for diagnostic consultations. The telecommunications, advanced medical diagnostics, and medical informatics provided by Primetime III have resulted in an integrated, worldwide system of telemedicine enabled healthcare delivery. This system extends from operating bases of Bosnia to the major military centers in Washington, D.C., Texas, California, and Hawaii. U.S.-based MHS Medical Centers are responsible for providing local telecommunications, video teleconferencing, teleradiology, and clinical staff support necessary to provide continuous specialty and sub-specialty real-time interactive and "store and forward" teleconsultation support. The selection of medical centers positioned in varying time zones around the globe facilitate 24-hour, 7-days per week support without requiring additional medical staffing. This is a very exciting global telemedicine concept in that telemedical consultations can literally "follow the sun" around the Earth.

Another wide-area telemedicine project is AKAMAI (a Hawaiian word meaning "clever"), an in-service project for electronic diagnosis and consultation, led by Tripler Regional Medical Center in Hawaii. AKAMAI allows for Tripler (a tertiary medical center) to support a referral area of more than one million square miles and a diverse military and civilian user group throughout the Pacific. The tong-term goal of this project is to expand telemedicine into the Pacific Basin by establishing a Pacific-wide telecommunications system for medical information, including Picture Archiving and Communication System (PACS), telemedicine consultation, teleradiology imaging, digital patient records, and new technologies as they develop (e.g., telesurgery and telepathology).'²

The U.S. armed forces are also engaged in a large-scale program of telemedicine research and development. For example, the U.S. Army has experimented with telemedicine to provide care to persons living on remote islands in the Pacific Ocean.'³ The armed forces also have in place projects to develop capabilities for the distant physiological monitoring of deployed troops and investigation of such technologies as telepresence and virtual reality.'⁴Thus, the military is poised and ready to take telemedicine to new heights into the new millenium.

Telemedicine Applied to Aviation

The aviation world has always been keenly interested in communications. Since the first balloon flight, communication has been a concern for an aircraft to maintain contact with ground facilities and other aircraft in the vicinity. The goal has always been to maintain a safe operating environment. Today an elaborate array of systems using multiple radio frequency bands, microwaves, satellites, and ground stations' are used to communicate and navigate the airways. Telemedicine represents a natural extension of this ability to transfer information to and from an aircraft while in flight or on the ground. With the increased use of aircraft to transport patients and the increase in the number of people flying in commercial aircraft, telemedicine is surely to become a tool that can be used in many different aviation settings.

The possibility that a health crisis might strike an airline passenger during flight has prompted discussion and investigation into adopting telemedicine capabilities aboard passenger aircraft. For example, United Airlines is evaluating a remote mobile device to monitor potential patients' vital signs. The monitor was installed on a Boeing 767 and tested for three months. Medical emergencies were simulated and procedures established for monitoring a stricken passenger's vital signs, then respond as needed. The device consists of a brief case-sized laptop computer and monitor that can electronically measure a passenger's EKG, blood pressure, heart rate, blood oxygen saturation, and respiration. The vital signs are transmitted via modem to a United Airlines flight surgeon on the ground who interprets them and offers medical advice.

In addition to commercial application, other aircraft where telemedicine capability could be useful include military and civilian aircraft for medical evacuation (MEDEVAC). In MEDEVAC aircraft where medical personnel, nurses and, at times, physicians are flown with the patients, the possibility of being able to effectively act upon a telemedicine consultation and intervene in an in-flight medical crisis is an attractive scenario.

The increasing use of the military in operations other than war in remote regions of the world also increases the likelihood that medical care may have to be rendered to patients within aircraft configured to provide the needed health care. This need is especially true in rapid deployment operations that may preclude the deployment of ground based medical facilities to the site. In these circumstances patients will not be "stable" during transport, as is the case in most flights over long distances. The ability to obtain expert consultation while treating patients in remote areas, whether aboard an aircraft or on the ground in a third world country, may be crucial to providing the care needed to save a critically ill patient.

As with any new technology used aboard aircraft, there are multiple questions that must be answered in order to provide the capability that is needed in a manner that is safe for the aircraft and provides accurate information. Some of the issues and questions that will need to be addressed for these and other applications of telemedicine use in aviation are:

What is the medical requirement? What clinical problem aboard the aircraft are we trying to solve?

What level of technology fulfills the requirement?

What amount of bandwidth is needed to support the technology selected?

How will the bandwidth be provided? (e.g., existing llF radio, satellite capability, etc.)

What aerodynamic considerations need to be taken into account for externally mounting additional antennas?

What are the legal issues? With greater information and connectivity, will patients have unrealistic expectations concerning what can be done for them? What are the flight safety issues and impacts of any proposed new technology aboard the aircraft? Could the workstations negatively impact navigation equipment tactical or non-tactical radios, or any other onboard electronic systems through electromagnetic interference?

The aviation community is taking notice of the advantages that telemedicine can bring to a flight environment. However, there is still much to be defined and addressed before the first approved system becomes a useful part of an in-flight emergency capability.

New Horizons for the Future

The application of "tele" technologies can be taken beyond the medical consultation and monitoring applications described thus far. The potential is great and the possibilities are only limited to our imagination and ingenuity. The following section presents robotic and virtual reality manifestations of telemedicine technologies currently being developed or planned. And as exciting and futuristic as the following examples may seem, the most awesome aspect is that we have barely begun to scratch the surface of what lies ahead.

Telepresence Surgery and Virtual Reality

Telepresence surgery is the name coined by Satatva, Green, and Simon ^16,17 to describe the application of existing and developing technologies in remote manipulation as applied to surgical procedures. The fundamental principle of a telepresence sLiq2ery system is to extend a surgeon's psychomotor skills and problem-solving abilities to t remote environment. The goal is to project a surgeons manual dexterity' to a remote location while providing real-time tactile and visual feedback from the location to the surgeon. In other words, we are dissolving time and space, allowing the physician to be at a distant place at the same time as another person without needing to travel there. Unlike telerobotic surgery, in which a robotic manipulator is directed by preprogrammed computer instructions, or surgical virtual reality, ¹⁹ in which manipulations are performed in a simulated environment, telepresence is a unique human-machine technology that directly' and transparently projects hit-man motion to a remote location.²⁰ It would be possible to operate at a place that is too distant or dangerous, such as the space station or a battlefield.

An exciting effort in the area of remote surgery is the current work conducted by Philip Green²¹of SRI International, the inventor of the Green Telepresence Surgery System. This is a prototype system that permits precise, accurate surgery remotely with all the illusion of being at the actual site. It consists of a remote work site and a surgeon's console, similar to a computer workstation. This system brings together 3-D vision, enhanced dexterity, and the sense of touch (through forcefeedback sensory information). These components provide the realism of actually operating at the remote site. The surgeon is operating on a virtual image in front of him/her. The surgeon's abilities are enhanced and surgery can be performed with greater skill and precision than teleoperations procedures using a conventional control interface. The current version is a one-handed 5-degree-of-freedom system with paired CCD cameras for stereo vision; the next generation will have two 6-DOF surgical hands and a stereoscopic laparoscope to replace the fixed cameras. The first prototype had the surgical console directly wired to the remote workstation and is being updated to a wireless system for remote operations. A military application of this system is to mount it in an armored mobile vehicle and posit ion it at the fir forward battlefield. When a soldier is wounded, the vehicle will drive to the site where the soldier is located allowing the surgeon at the hospital to operate immediately upon the casualty on the front lines. Once the system is perfected, it can be transitioned to civilian LI SC for disaster relief and emergency care.^2~

To enhance their work, physicians will also be able to bring in many different digital images, such as the patients CT or MRI scan, and fuse them with real-time video images giving the surgeon a type of "x-ray vision." In addition, virtual environments can satisfy the need for training in medical and surgical procedures. For decades, pilots have been training on flight simulators that have become so realistic that a myriad of perfect take-off and landings can be safely performed before the first actual flight takes place. So too will the surgeon of the future be able to perfect surgical skills and rehearse the surgical procedure before operating on the first patient. For example before doing a surgical procedure, the surgeon could sit at the workstation and practice on a virtual patient to simulate the operation and then flip a switch and begin operating on the real patient with precisely the same workstation.

Hon²⁴ has developed virtual reality laparoscopic surgery simulators consisting of a plasitic torso into which handles of instruments are mounted (to provide force feedback). The virtual abdomen (liver and gall bladder) is graphically displayed on a video monitor and surgeons and students can practice specific procedures. Satava² has taken a different approach with a virtual abdomen created for an immersive experience utilizing helmet-mounted display and Dataglove^TM. Using a virtual scalpel and clamps, the abdominal organs can be operated upon and explored. These examples are but the first of many potential applications of virtual reality for medical and surgical simulation and education.

Conclusion

We are standing at the edge of a new frontier that is maturing with the help of a multi disciplinary team of scientists, engineers, and others. The vista before us shows an unfolding story of advances in telemedicine. Embedded within this story are key events and observations:

Aviation and space technologies have provided significant technology "roots" for telemedicine development and will continue to play major roles in its future.

The Military and Space programs as well as independent rural and health community efforts have provided an historical experience base from which we can judge the value of telemedicine and plan for its future.

Telepresence surgery and virtual reality are making possible the transport of movement skill. Medical experts will not only consult and advise but also "do."

Fertile ground exists for creative individuals planning future careers in telemedicine related 10 its use in aviation and space flight, military battlefield needs, simulator development, telepresence technology development, virtual reality applications, disaster management, and medical outreach to underdeveloped and third world countries.

Telemedicine has the potential to medically unite the world and make possible the sharing of much needed expertise in times of great need.

In the future, a new framework for the modern medical scenario will emerge enabled by the digital communication infrastructure. The physician of the future will be a "digital physician." Today, almost any information needed about a patient can be acquired electronically. Tomorrow, medical expertise in the form of transmittable psychomotor skills (teleoperation, telemanipulation, and telesurgery) will complete the loop, and medical distance independence will arrive.

As medicine continues to accelerate technologically, a major question to ask is, "Where does it leave the human?" Intuitively, we know that technology will never totally replace the human health care provider. The potential is high that a significant and positive enhancement of the medical process will result. But are we de-humanizing medicine? How far can technology take us in the healing art? What will be the impact and acceptance of an electronically-generated healing touch? Who knows? We may discover that in machine systems where humans are truly in the loop, our human presence and essence will always be felt. And, for a finite moment, we will become that object which extends our reach.

References

1. Grigsby, J., Kaehny, M.M., Schlenker. RE., et al. "Analysis of expansion of access to care through use of telemedicine and mobile health services." Report I: Literature Review and Analytic Framework. Denver, CO: Center for Health Policy Research, 1993.

2. Pool, S.L., Stonsifer, J.C., and Belasco, N. "Application of telemedicine systems in future manned space flight." Paper presented at Second Telemedicine Workshop, Tucson, AZ, Dec., 1975.

3. Houtchens, B.A., Clemmer, T.P.. Holloway, H.C., et al. "Telemedicine and international disaster response: Medical consultation to Armenia and Russia via a telemedicine spacebridge." Prehospital and Disaster Medicine, 8: 57-66. 1993.

4. Nicogossian A.E. "Final Project Report: US-USSR telemedicine consultation spacebridge to Armenia and Ufa." Paper presented at the Third US-USSR Joint Working Group on Space Biology and Medicine, Moscow and Kislovodsk, USSR, 1989.

5. Riggs, R.S., Purtilo, D.T., Connor. D.H., and Kaiser, 3. "Medical consultation via communications satellite." Journal of the American Medical Association, 228: 600-602, 1974.

6. Ferguson, E.W., Doarn, C.R., and Scott, J.C. "Survey of global telemedicine." Joti-roal of Medical Systems, 19: 3546, 1995.

7. R.S. Johnston, L.F. Dietlein, and C.A. Berry (eds.). Biomedical Results of Apollo. NASA SP-368, U.S. Government Printing Office, Washington, DC, 1975.

8. Crump, W.J., Levy, B.J., Billica, R.D. "A field trial of the NASA telemedicine instrument pack in a family practice." Aviation Space Environmental Medicine, 67(11): 10801085,1996.

9. Billica, R.D., Chief. Medical Operations, Private communication, NASA Johnson Space Center, Houston, TX, January 15,1997.

10. Cawthon, M.A., Goeringer, F.. Telepak, R.J., et at. "Preliminary assessment of computed tomography and satellite teleradiology from Operation Desert Storm." Lnvestigative Radiology, 26: 85~857, 1991 -

11. Spiller, R.E., Hellstein, J.W., and Basquill, P.J. "Radiographic support in highly mobile operations." Military Medicine. 155: 486-489, 1990.

12. Garshnek, V. "Moving information not patients: the Department of Defense experience with telemedicine in the Pacific." Presentation to the Western Occupational Health Conference, Maui, Hawaii, Octoher, 1996.

13. Delaplain, C.lu., Lindborg. C.E., Norton, S.A., and Hastings, J.E. "Tripler pioneers telemedicine accross the Pacific." Hawaii Medical Journal. 52: 338339, 1993.

14. Satava, R.M. "Virtual reality and telepresence for military medicine." Computers in Biology and Medicine, 25(2): 229-236, 1995.

15. Anon. "Mile High Medicine." Hospitals and Health Networks. 70(14): II, 1996.

16. Green. P., Satava, R., Hill, J., Simon, I. "Telepresence: advanced teleoperator technology for minimally invasive surgery." Surgical Endoscopy, 6: 62~7, 1992.

17. Simon, lB. "Surgery 2001: Concepts of telepresence surgery." Surgical Endoscopy, 7: 462463,1993.

18. Sheridan, T.B. "Defining our terms." Presence, Teleoperators and Virtual Environments. I: 272-274, 1992.

19. Durlach, N.t., Mavor, A.S. (eds.). Virtual Reality: Scientific and Technical Challenges. Washington. DC: National Academy Press, 1995.

20. Thring, M.W. Robots and Telechirs. New York: Wiley and Sons, 275-278, 1983.

21. Green, P.S., Hill, J.H., and Satava, R.M. "Telepresence: dextrous procedure in a virtual operating field." Surgical Endoscopy, 57: 192,1991.

22. Satava, R.M. "Robotics, telepresence and virtual reality: a critical analysis of the future of surgery." Minimaly Invasive Therapy, 1: 357-363,1992.

23. Satava, R.M. "Virtual reality and telepresence for military medicine." Computers in Biology and Medicine, 25(2): 229-236, 1995.

24. Hon, D. "Tactile/visual simulation: realistic endoscopic experience." Proceedings of Medicine Meets Virtual Reality. San Diego, CA, June 1-2, 1992.

25. Satava, R.M. "Virtual reality surgical simulator: the first steps." Surgical Endoscopy, 7: 203-205, 1993.

Note: The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Army or the Department of Defense.