ORIGI.NAL ARTICLES

Authors alone are responsible for opinions expressed in the contribution and for its clearance through their federal health agency, if required.

BG Russ Zajtchuk, MC USA GEN Gordon R. Sullivan, USA

I would say that two contrary laws seem to be wrestling with each other nowadays: the one, a law of blood and death, ever imagining new means of de-struction and forcing nations to be constantly ready for the battlefield—the other a law of peace, work. And health ever evolving new means of delivering man from the scourges which beset him. Which of these two laws will ultimately prevail Cod alone knows.

Notwithstanding the low number of casualties the United States and our coalition allies sustained in the Persian Gulf in 1991, the lethality of the modern battlefield requires that advanced lifesaving techniques—used from the foxhole to the Army's medical centers in the United States—continue to be developed. Minimizing the numbers of American battlefield deaths is inherent in our national military strategy. The Army, in partnership with the Advanced Research Projects Agency(the Department of Defense's leading technological innovator),is developing several technologies that will improve survival of battlefield casualties.

Combat trauma, although historically less important than disease or adverse environment as a source of attrition in wars, may have received greater public interest in recent decades because public attention has focused on those who are killed or wounded fighting for our nation. Clearly, the matter has al-ways been a source of concern for soldiers, and especially for combat leaders who are responsible for their welfare and safety. The incidence of battle casualties has come to be accepted not only as an index of political tolerability for military actions but also as a measure of military success or failure.

In conventional military planning, the number of soldiers who become battle casualties is measured as a rate (the percentage of the total force killed, wounded, missing, or taken prisoner per battle day). The number of casualties is deter-mined by many factors, the most important of which include

This manuscript was received for review in March 1994. The manuscript was accepted for publication in December 1994.The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of Defense, the Department of the Army, or the U.S. Government.

the outcome of the combat, tactical posture, weapons used, and size of the unit in question. The larger the unit, the lower the casualty rate (i.e., large units have a greater proportion of soldiers in combat-support or combat-service-support roles; these soldiers are less likely to be exposed to heavy enemy fire). In this century, it has been unusual for a division - a formation of 10.000 to 20.000 soldiers - to lose more than 10% per day.¹Nevertheless, higher rates have been recorded. For example, in 1916, on the first day of the Battle of the Somme, several at-tacking British divisions lost more than 50% of their total strength in a few hours.²

In the battle of la Drang, in Vietnam, the attrition rate for United States forces was 35 %.³

Medical implications of combat trauma usually have been assessed in terms of mortality (the percentage of the casualty population that is fatally wounded) and morbidity (the total number of man-days lost, or the average number of days a combat casualty is not effective for medical reasons). Contemporary American analysts quantitate combat mortality by two normalized statistics: the percentage killed in action (those who die before they reach a medical treatment facility) and the percentage who die of wounds (those who die while receiving medical care). The definitions of these casualty categories may differ from country to country and from war to war. However, data compiled from seven wars during the last 150 years (for those instances in which a force is able to provide state-of-the-art combat casualty care) indicate that approximately 20% of those who sustain combat injuries are killed in action.⁴ Substantial progress has been made in reducing the mortality of those who survived to receive treatment, and there has been a decline in the percentage of those who die of wounds: from 16%in the Crimean War to 3% to 4% in recent wars.⁵-⁸ This improvement no doubt reflects both the gradual development of an organized system of rapid and safe evacuation of the wounded from the battlefield and the achievements of modern surgery (Fig. 1).

Fortunately, data exist that deal with the epidemiology of combat injuries during the Vietnam conflict. These unique, unpublished data are contained in a study carried out by Wound Data and Munitions Effectiveness Teams (WDMET) from the U.S. Army and U.S. Marines. Analysis of the WDMET data may help us understand what can be done to decrease combat mortality. For example, the WDMET data base indicates that a relative constancy exists in the percentage of soldiers killed when a projectile strikes the body (usually about75 % are fragments from explosive munitions and 25% are bullets from small arms). The overall probability that the projectiles will injure the brain, heart, large blood vessels, or other vital organs, causing immediate death, is about 1 in 5. Wounds of the heart and brain are especially likely to kill. For U.S. Army personnel in Vietnam, the highest probabilities of being killed by a gunshot were 4 in 5 for chest wounds and 9 in 10 for head wounds (COL R. Bellamy, MC USA, Walter Reed Army Medical Center, Washington, DC: personal communication, October 1993).

About 50% of soldiers killed in action in Vietnam exsanguinated on the battlefield. It is estimated that simple first aid could have saved up to 20% of these casualties.⁹ Additionally.10% of the fatally wounded died from a tension pneumothorax, diagnosed from postmortem roentgenography. The conclusion is that rapid intervention would have been lifesaving.

Most battlefield deaths occur rapidly despite the fact that the median time required for a combat medic in the Vietnam conflict to reach and begin treating a combat casualty was only 4minutes after wounding.¹⁰ Analysis of the WDMET data base shows that. in the unique tactical circumstances that characterized the Vietnam conflict (i.e.. a counterinsurgency war fought with lethal assault weapons), approximately 67% of those killed in action died within 10 minutes of wounding (Fig.2). Of the remaining 33%. most died between 10 minutes and 1hour after wounding (R. Pruitt, MD, MPH, Assistant Director for Research, Casualty Care Research Center, Department of Emergency and Military Medicine. Uniformed Services University of the Health Sciences, Bethesda, Maryland: personal communication, October 1993). Some of these casualties did not receive timely treatment because the battlefield medic could not locate them, or battlefield conditions prevented the medic from reaching them. We conclude that the more rapidly a seriously wounded soldier receives medical attention, the better the chances of survival. In addition, the chances of survival are related to (1) the medical skill and the experience of the early intervenors and (2) the diagnostic and interventional devices available to facilitate medical care.

Within the Department of Defense, the Army Medical Department's Center and School (located at Fort Sam Houston, Texas) analyzes the epidemiology of combat trauma from previous wars to predict the casualty rates for future wars, and prepares an extensive data analysis and interpretation of com-bat casualties. This concept-based, requirements-analysis process ranks issues according to priorities of battlefield medicine (Table 1). The Advanced Research Projects Agency also per-forms a combat casualty care requirements study. Together these studies form the "basis for the determination that advanced medical technology can be applied to modern battle-field medicine. With the skills of our medics and combat life-savers (i.e.. ordinary soldiers who are given extra first aid training and who assist the medic after a battle) enhanced, combat casualty care can be improved, with a corresponding decrease in soldier mortality, morbidity, and the aggregate costs of rehabilitation health care.

The Advanced Research Projects Agency is committed to a multi-year program in advanced medical technologies that involves the transition of devices not only to the medical departments of the armed services but also to individual combatants in the Army and Joint Special Operations Commands. Five technological initiatives constitute a comprehensive, integrated development plan:

• advanced diagnostics.
• advanced trauma care.
• the health care information infrastructure,
• telemedicine, and
• medical simulation.

Each technology focus area pertains directly to the quality and accessibility of medical care that reaches the individual soldier in the combat zone. When integrated with virtual reality-based education and training, the skills of the military physician on the modern battlefield will be enhanced with technology-driven life-support measures.

These technologies can also be converted readily to the civilian health care system, centering on the practice of medicine in rural America. Key to the success of using advanced technologies in modern medicine in remote settings is the exploitation of the emerging capabilities of telemedicine, which uses advanced information systems to detect casualties instantly, focus aid on those who need it most. project physicians' skills and experience onto the battlefield, and bring to bear all our resources to assist physicians who are treating difficult cases within a theater of war or a civilian disaster.

Advanced Diagnostics (The Personnel Status Monitor)

The Personnel Status Monitor, which would be worn by all soldiers as part of the combat uniform, is a miniaturized device that combines advanced environmental sensors and nonintrusive physiological sensors with a processor, geopositioning receiver, and low-power wireless radio (Figs. 3 and 4). The Personnel Status Monitor would monitor the soldier's vital signs continuously, but would remain passive unless either (1) it were queried by a commander, in which case it would reply with the soldier's geographic location and vital signs, or (2) the soldier's vital signs departed from established norms, in which case the Personnel Status Monitor would repetitively transmit this location and vital signs until it was shut down by a medic. The Personnel Status Monitor would interact with global-positioning satellites and would incorporate the most advanced form of wireless telephony: Broadband Code Division Multiple Access.

The" Personnel Status Monitor has the potential to reduce combat mortality in several ways:

—By increasing command awareness of precisely where soldiers are located on the battlefield, it will help prevent casualties from friendly fire (a significant portion of all battle casualties may be caused by weapons inadvertently hitting the wrong targets).

—It will provide the individual soldier with the ability to detect chemical and biological warfare agents.

—It will enable combat medics to commence triage within moments after a soldier is hit, and because the precise location and critical level of injury or shock of each wounded soldier are known, it will optimize available treatment and evacuation.

—It will identify dead soldiers and thus obviate the need to send evacuation teams into hostile environments.

Advanced trauma care attempts to preserve organ function and prevent exsanguination. Pharmacologic technology now in research and development will attempt to achieve a state of suspended animation similar to hibernation.

The goal is to preserve critical organ function at minimal physiologic status while controlling hemorrhage, reversing systemic shock, and preventing hypoxia by using auto-con-trolled devices to provide immediate mechanical (e.g.. a tourniquet) or pharmacologic therapy. Once pharmacologic stabilization (or early surgical stabilization) has been achieved, the patient will be evacuated in a Critical Care Pod. The Pod will allow long-range evacuation under controlled physiologic and closed-cycle environmental conditions, and it will function like a hospital intensive care unit. The Pod will

—be coupled with the casualty's Personnel Status Monitor for continual, in-transit monitoring of vital signs:

—preserve stability by administering fluids or drugs, or by summoning human intervention:

—mechanically support vital functions: and

—provide protection from natural or military hostile environments.

Integrated with the global grid of telecommunications networks, a medical informatics infrastructure will support the entire technology base. Medical information must flow seam-lessly and transparently on all levels of patient care. For this to occur, a platform-independent medical record system, such as the Battlefield Electronic Patient Record, will ensure immediate continuity, distribution, and accessibility of medical information from the forward battlefield to the rear-echelon support in United States-based medical centers. This information will be archived in multimedia data bases (e.g.. laboratory studies, radiologic and pathologic images, in-patient medical records) and be available over a worldwide telecommunication system for real-time, interactive collaboration among physicians. In addition, the infrastructure will provide a decision-support sys-tem—an algorithm-derived computer program that cans assist physicians, nurses, corpsmen and paramedics in assessing and treating patients.

The information infrastructure being designed will enlarge the window for diagnosis and treatment. This capability will affect not only battlefield casualties but also civilian patients in remote areas of the United States. The technological solutions to enhancing perceptions and cognition evolve from intelligent systems engineering to provide point-of-service multimedia access to real-time data. The augmentation of decision making will allow generalisis and specialists to confer by revolutionary communication links to provide extended emergency, as well as follow-up, medical care.

Telementoring provides each combat medic with one-way video and two-way voice and data communication with a physician (or a physician's assistant), so that early, expert advice can contribute to the lifesaving efforts. Present proposals inte-grate the video into the medic s protective goggles and provide

a throat microphone, small earphone, and palmtop computer, all linked via Broadband Code Division Multiple Access to the mentor. Both the casualty and the combat medic will benefit from the coaching, and the physician, who will observe the first aid that is administered in the field, will be able to prepare for further treatment on evacuation. Furthermore, observation of what transpires during resuscitation on the battlefield will aid in the development of better training programs for medics.

Teleconsultation allows a physician in a forward medicalunit to consult with a specialist located elsewhere, including Army tertiary-care hospitals and civilian hospitals in the United States. The U.S. Army Medical Department is already using communications to bring the expertise of the staff at Walter Reed Army Medical Center. Washington, DC, to support Army medics in Germany, Somalia. Croatia, and Macedonia.

By means of a digitizing camera, laptop computer, and modem the medic in Europe transmits photographs (and an accompanying descriptive text) of the patient at the remote site to Walter Reed Army Medical Center for analysis by a specialist-in essence, intercontinental medical teleconsultation.

This simple first step with a still camera and textual data will soon be expanded to real-time, full-color video with simultaneous, two-way and/or real time monitoring of vital signs and collaborative interaction among physicians at medical centers and remote sites. Technology promises that teleconsultation can soon be supported by a worldwide network of high-capacity communications—a global grid of fiber-opticcables and satellites, with Asynchronous Transfer Mode switches and related protocols for handling information—capable of transmissions at hundreds of millions of bits per second (e.g., the complete medical records of 1.000 patients could be transmitted overseas in seconds).

The result of this high-capacity telecommunication network is to project a physician's abilities to a remote site. For example, during advanced-technology demonstrations in military field exercises conducted in June 1993, current technology supported real-time video, two-way audio, text and data consultation from the field to Walter Reed Army Medical Center and the University of Virginia. This consultation included multiple, simultaneous "windows" on the video monitors, which permitted the physician at the medical center to interact and collaborate with a Mobile Army Surgical Hospital surgeon by simultaneously viewing

—the wounded soldier's medical record:

—graphic displays of the soldier's vital signs and ECG:

—a transmitted, digitized X-ray film: and

—real-time video.

The consulting physician was able not only Co "examine" the patient and talk with the surgeon, but also to electronically "point" or "draw" critical instructions on the video or X-ray image for the surgeon. The level of collaborative interaction becomes so realistic that the consulting physician feels as if he or she is actually present in the remote location. This allows expert medical support to be provided far forward, while actually decreasing the number of medical and logistical support personnel on the battlefield.

Telesurgery extends the concept of teleconsultation to physical intervention by the remote specialist, who is able not only to see and hear what is transpiring with the patient, but to participate in surgical procedures by pointing (e.g.. with a laser spot) or by actually manipulating instruments in the operating field. The Army-Advanced Research Projects Agency partners are developing a prototype Remote Telepresence Surgery system, which has been successfully demonstrated in laboratory animals and simulated field exercises.^11.12 The Remote Tele-presence Surgery consists of two components: the remote operative site and a central surgical workstation. At the remote site are a three-dimensional camera, remote-manipulator instruments with great dexterity and tactile sensory input, and stereophonic microphones. At the workstation are a three-dimensional video monitor, stereophonic sound, and surgical instruments that "handle" with precision control and dexterity, as well as with tactile and force-reflecting feedback. This system will enable renowned surgical specialists at regional medical centers to bring their expertise to casualties on the battlefield with the same sensory clarity as if the procedures were being done in the specialists' own hospital operating rooms.

By utilizing the global telecommunications network with telepresence surgery, multiple surgeons in different cities could participate in a single operation, or a distant super-specialist could become the first assistant to a surgeon in are mote location. Likewise, a surgeon could operate in a dangerous or inaccessible place (e.g.. a submarine, Antarctica, or a space station), or surgery could be performed in a third world country without the expense and time of traveling there.

Microsurgery, or even cellular surgery, may one day be per-formed. The telepresence surgical workstation currently works on an exact one-to-one scale. However, the scale of surgery could be changed to a microscale, with greatly magnified vision and miniature or microscopic instruments. This would permit the surgeon to operate on tiny structures or possibly on various organelles within an individual cell, like mitochondria or Golgi bodies.¹¹

Medical simulation is an advanced, virtual reality technology that provides a unique, revolutionary, educational environment. Military and civilian physicians, nurses, physician's assistants, and emergency medical technicians and combat medics can be trained via the simulation of the human body. As is also true of the goals of the Defense Simulation and Modeling Office of the Department of Defense, no suggestion is made here that the virtual environment will replace true set-tings. Rather, the assertion is that the virtual reality based, problem-solving environments will accelerate the user's learning capability.

The program has three objectives:

1. to achieve virtual representation of human structure and function:

2. to provide a near-seamless transition from training to clinical practice: and

3. to integrate the medical care of combat casualties with

operational battlefield requirements... Through liaison with the Visible Human Project of the National Library of Medicine, and capitalizing on the advanced war game simulations developed by the Department of Defense at the Institute for Defense Analysis, the medical simulation program will work to develop a credible simulation of the human body. The Visible Human Project will provide digital magnetic resonance imaging and computed tomography data from selected male and female human cadavers—forming a real data set for the development of commercial human simulators. The technological challenge will be to mimic the structure and function of the human body. Structures and relationships that allow the simulation of tumors, the paths through tissue taken by projectiles, and the expression of normal human variations are among the goals to be attained. Further technological challenges entail representing the dynamics of human physiology. Simulated casualties must be able to hemorrhage, go into shock, and have vital-sign changes that mimic actual trauma-tic or pathologic events.

Simulation must also approach normal human sensory perception. Tactile sensation, voice, and force-feedback will be programmed into the simulation. An operator wearing sensate gloves will "feel" a scalpel incise the tissue. The three dimensional perception will allow the operator—whether surgeon, combat medic, or medical student—a journey into the human body.

Simulation will also enable physicians to maintain their skills as well as enhance their ability to provide far-for ward medical and surgical intervention. In a setting that forgives mistakes, residents and surgeons can practice surgical approaches or plan the strategy for the next day's surgery while the simulator illustrates the consequences of their surgical judgments.

The impact of whole-body virtual simulation on under-graduate medical and continuing medical education programs will dramatically reduce the need for human cadavers and live-animal experimentation. In addition, simulation can help medical students integrate traditionally separate academic disciplines. Through this new medium, anatomy, physiology, and biochemistry can couple with the clinical sciences. Physical examination, clinical diagnosis, and the pharmacologic con-sequences of intervention are some of the interactions that simulation could help make a seamless human learning experience.

Just as the U.S. Army pioneered the use of now-primitive helicopters in Korea to evacuate the wounded, and used them extensively in Vietnam to reduce mortality of the wounded, so the Army continues to develop advanced technologies to main-tain the world s finest combat casualty care systems. Our battlefield health care providers-not only Army medics but also individual combat soldiers—are prepared to move anywhere in the world, whether in peacekeeping, peacemaking, or full-scale combat operations, to take care of America's most precious resource—its sons and daughters.

The technologies that have been discussed in this paper were partially demonstrated in June 1993 during an Army War fighting Demonstration at Fort Gordon. Georgia, and in July 1993 on the White House grounds. During the coming year the equipment and procedures will be refined: further exercises will be conducted; and the demonstration will be repeated with trained personnel and upgraded equipment, early in 1995.

Advanced diagnostic procedures, new methods of medical and surgical intervention, and simulation used to train physicians and paramedical personnel are direct applications of Department of Defense-technology-development initiatives. When coupled with landmark telecommunications capabilities, the advanced technology now in development can profoundly extend the walls of tertiary-care medical centers to remote areas worldwide. This technology-based capability will provide opportunities to establish changes in the doctrine and policy of medical care.

Whether the casualty falls in a theater of war or is an accident victim in the United States, the immediate health care needs are similar: the most accessible and highest-quality medical care delivered as soon as possible. Many of the technological innovations discussed here can be used in the civilian health care system of the United States, assuring the dual use of Department of Defense technologies.

Since this paper was submitted in March 1994. a great deal of progress has been made in the maturation of the systems de-scribed. The Army Medical Department has been chosen as executive agent to develop the new capabilities for the Department of Defense. The authors believe that the Army Medical Department will be prepared for the information-based, power-projection Army of the 21st-century. Additionally, we'll re-engineer the way medicine will be practiced in the future: improve quality and access, and reduce cost.

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