Modern Combat Casualty Care
INTRODUCTION
With malice toward none, with charity for all, with firmness in the right as God gives us to see the right, let us strive on to finish the work we are in; to bind up the nation’s wounds; to care for him who shall have borne the battle, and for his widow and his orphan—to do all which may achieve and cherish a just and lasting peace, among ourselves, and with all nations.
Lincoln’s Second Inaugural Address, March 4, 1865
This memorable quote hangs over the door of many US operating rooms in the combat theater. It provides an appropriate focus regarding the privilege and responsibility of those engaged in military medicine. Caring for those who have been injured on the battlefield has been an integral part of the fabric of medicine since the days of the ancient Greeks. Working in an austere, and often hostile, environment with limited resources is a humbling and intensely emotional experience. It is an unfortunate but equally accurate truism that war advances our understanding of care of the injured patient unlike any other worldly event.1 The scope of this chapter will attempt to characterize the most recent recognitions and advances that have emerged as lessons learned over the past years of armed conflict.
Many of the lessons of modern military medicine are, in fact, not new but simply principles recognized by many previous generations of combat medics. Hypotensive resuscitation (Walter Cannon, MD, World War I), the value of whole blood transfusion (Edward Churchill, MD, World War II), and the utility of vascular shunts (the Korean War) are just a few examples of the pivotal lessons “rediscovered” during the current conflicts. Military medicine by its very nature is challenged by the task of preserving its own history and the lessons learned. The majority of providers of combat medicine return home and to civilian and academic practices without fully cataloging and preserving lessons learned. The military medical corps’ challenge is to maintain and promote ongoing combat medical support and research in periods between conflicts. Generations of medical officers may come and go without seeing an armed conflict, and lessons learned are all too often lessons forgotten.
Modern warfare has changed in scope and condition. The classic large battlefield campaigns witnessed in World War I, World War II, and Korea (and feared during the Cold War with Russia) are less relevant in today’s global security scenario. Over recent decades, armed conflict in the Global War on Terror has emphasized the necessity of fluidity, precision, and speed of engagement. The current battlefield is shaped by the reality of the asymmetrical or nonlinear battlefield. Lines of engagement may be spread out over a wide geographical continuum and the forward edge of the combat zone may shift hundreds of miles in a single day as rapidly mobile armored and cavalry units mobilize with dramatic speed and capability.
One of the key elements in lessons learned during the reshaping of military medicine has been the recognition (learned long ago) that the military medic must remain close to the forward deployed soldier in order to make a difference. The “reengineering” of modern military medicine has emphasized the necessity of mobility and proximity for forward medical units. This has resulted in the (re)creation of small, robust surgical teams that can deploy rapidly (hours) and conduct lifesaving/life-stabilizing procedures. This far-forward presence is combined with the development of a logistics and evacuation process providing rapid, high-intensity, and ongoing care from these far-forward locations to more rearward facilities. Fig. 52-1 is illustrative of one of these small austere forward units. The reader is urged to note that despite the changes of modern medicine, many of the aspects of these units look very similar to the iconic Mobile Army Surgical Hospital (MASH) units of Korea. The reader is also encouraged to consider the context of this austere setting over the course of this chapter. This chapter will attempt to detail the current state of the art from prehospital care to far-forward surgery, and the en route care process. Key medical lessons learned will be highlighted, as well as a discussion of the systemwide changes implemented across the medical corps of all services.
FIGURE 52-1 The outside structure (top right and top left), the operating room (bottom left), and the medical personnel of the 909th Forward Surgical Team; FOB Shank/Afghanistan.
Definitions
As a first order of business, it is appropriate to establish definitions used by the military (and in this chapter) with respect to the military patient. Holcomb et al.2 clarified our understanding and attempted to provide a uniform framework for discussion of combat casualties. The following definitions taken from the article of Holcomb and Bellamy standardize the numbers and allow a reasonable retrospective comparison between various military conflicts.
Wounded in Action (WIA)
This is a term used to define combat-injured casualties and is the sum of three subgroups as demonstrated in Fig. 52-2. Conventionally, the subgroup of surviving WIAs who return to duty (RTD) within 72 hours is excluded from the denominator when proportional statistics are presented. This is significant because this group traditionally represents almost 50% of all WIAs. The number and classification of wounded and deaths from combat is classically used to provide insights into the lethality of battle and the effectiveness of the systems of care and evacuation, and to focus attention on required areas of research.
FIGURE 52-2 Explanation of terminology for combat casualty calculation(s).
Case Fatality Rate (CFR)
This term refers to the fraction of the injured, all those WIAs including all those who die, expressed as a percentage (Fig. 52-3). Summary statistics provides a measure of the overall lethality of the battlefield in those who are wounded. It includes those who are returned to duty that are excluded in the denominator of died-of-wounds (DOW) and killed-in-action (KIA) rates defined below. A point of confusion in the past has been use of this statistic with and without the RTD population, thereby creating a major source of confusion when comparing data sets from different conflicts using a differing definition. Insufficient detail is provided by a CFR for detailed medical planning for reasons that will be discussed subsequently. The CFR is not a total mortality rate that would describe all deaths relative to the entire deployed population at risk.
FIGURE 52-3 Mathematical calculation of case fatality rate.
Killed in Action
This term refers to the number of combat deaths that occur prior to reaching a medical treatment facility (MTF such as battalion aid station [BAS], forward surgical unit, combat support unit, or higher levels of hospital care where a medical officer is present) (Fig. 52-4). This term is expressed as a percent of the WIA minus the RTD. This statistic provides a measure of (1) the lethality of the weapons employed in the conflict; (2) the effectiveness of the point of wounding and medical care far forward; and (3) the availability of evacuation from the tactical setting. Factors that impact on KIA rate include body and vehicle armor, effectiveness of the trauma systems in the forward area, timing from wounding to first treatment, and care in the field by the casualty, buddy care, or the medic/corpsman.
FIGURE 52-4 Mathematical definition of killed in action.
Died of Wounds
This term refers to the number of all deaths that occur after reaching an MTF. This term is expressed as a percentage of the total wounded minus the RTD (Fig. 52-5). This statistic provides a measure of the effectiveness of the MTF care and perhaps also the appropriateness of field triage, initial care, optimal evacuation routes, and application of a coordinated trauma systems approach to a combat setting. Deaths that occur anytime after admission to an MTF are included in this category.
FIGURE 52-5 Mathematical definition of died of wounds.
It is important to note that the calculation of KIA and DOW utilizes different mathematical terms. The statistical figure of DOW focuses on the survival of the cadre who are alive long enough to undergo treatment at an MTF. Thus, the DOW rate is a surrogate of the effectiveness of MTF care. It must also be recognized that the final value(s) of KIA and DOW are in part reciprocal in nature and influenced by tactical considerations of the theater. Extremely rapid evacuation from the point of wounding to an MTF will increase the relative number of dramatically injured casualties who arrive alive in order to receive care. This may shift the relative death rate from those killed in action in the field to those who died of wounds at medical treatment facilities. In previous conflicts (World War II, Korea) or in instances of increased evacuation times (remote regions of Afghanistan), the number of casualties who succumb prior to entering an MTF (i.e., KIA) will increase. With this perspective and background in mind, a more meaningful comparison may be obtained when comparing the current conflict with previous wars, as displayed in Table 52-1.
TABLE 52-1 US Military Deaths in Historic Context
Thoughtful reviews of KIA, DOW, and CFR rates for combat trauma are important for optimal medical planning, training, research, and resource allocation. The need to bring combat casualty epidemiology to a civilian standard requires utilization of both technology and organization that are routinely utilized in the US civilian trauma community. Thanks to efforts by the Deputy Assistant Secretary of Defense for Health Affairs and the Surgeons General of each of the armed services, raw data appropriate for this effort are currently being collected. Standard operational definitions are in use for the cataloging and analysis of this complex information. Currently the Joint Theater Trauma Registry (JTTR) employs approximately 75 civilian personnel in the United States and 10 military personnel deployed in a far-forward setting. Injury severity data are recorded, scored, and analyzed by methods that both meet trauma-community standards and are appropriate to meet the unique aspects of battle injuries. The current conflict will be the first in history from which detailed, concurrent analyses of the epidemiology, nature and severity of injuries, care provided, and patient outcomes can be used to guide research, training, and resource allocation for improved combat casualty care.
COMBAT TRAUMA EPIDEMIOLOGY
A recurrent theme throughout this chapter is the significant synergy or shared information between the civilian trauma community and military medicine. In the decades following the Vietnam War, the American College of Surgeons and its Committee on Trauma developed and matured a robust trauma system and care model. A generation of trauma providers trained and came to understand the benefits of working within a mature trauma system (including verified trauma centers) as well as the utility of trauma registries and performance improvement processes. These same providers were trained in the civilian trauma sector and subsequently brought this model forward as a desired standard of care when entering military service.
One of the most important elements of this “translational” process was the recognition of the need for a capable and effective trauma registry tool for the military and its combat casualties. In all previous conflicts (including the first Gulf War), collection of wounding data was, at best, haphazard and retrospective. In response to the lack of a Department of Defense registry, a JTTR was developed prior to the initiation of the Global War on Terrorism. The registry process was heavily modeled after civilian counterparts such as the National Trauma Data Bank (NTDB). Through the efforts of the three Surgeons General and the Department of Health Affairs, a policy paper and minimum essential data element set was created.3 The repository for these data is at the US Army Institute of Surgical Research at Fort Sam Houston, Texas. The JTTR has provided the basis for a significant number of peer-reviewed papers over the past 8 years and continues as an invaluable tool to the continued understanding of military wounding data and epidemiology.
Accurate understanding of the epidemiology and outcome of battle injury is essential to improving combat casualty care. The process of accurate data collection during combat medical operations remains notoriously difficult due to the austere and fluid nature of combat medicine. The ability to account for mechanism of injury, time to evacuation, the use of body armor, and the prehospital care rendered are just a few of the critically important, yet very difficult parameters that require tracking. The Department of Defense is actively investigating electronic and automated data acquisition systems for forward field use (electronic dog tag, PDAs, etc.). At this time, the majority of data retrieval and transmission continues to rely on pencil and paper. In its current form, the JTTR employs a cadre of approximately 75 civilian personnel within the continental United States (CONUS) and 10 forward deployed trauma registry personnel in the theater of combat.
DISTRIBUTION OF INJURIES
The sources of injuries during the Iraq/Afghanistan war are not entirely different than previous conflicts. The increasingly widespread use of the improvised explosive device (IED) has led to the recognition of a particularly devastating wounding pattern combining high blast energy with multiple penetrating fragmentary wounds and thermal injury. The continued evolution and maturation of the JTTR has provided the basis for relatively frequent analysis of wounding patterns and wounding outcomes. The most recent analysis (2008) is presented in Table 52-2.
TABLE 52-2 Mechanism and Distribution of Injury Encountered During Operation Iraqi Freedom and Operation Enduring Freedom
Whether from small arms fire or from IED injuries, combat wounds are generally distinct from those encountered in an urban trauma center setting. High-velocity military weapons create much greater patterns of tissue injury and destruction than seen with handguns. Fragmentary projectiles created by IEDs (secondary blast effect) prove to be unpredictable in depth of penetration and injury potential. The universal employment of effective body armor by US and coalition forces has pushed the relative distribution of the injuries away from the core structures (head, chest, and abdomen) and toward the extremities and unprotected regions (arms, legs, neck, and groin) (Fig. 52-6). The protective effect of body armor is obvious during the recent conflicts and is best exemplified by comparing the distribution of injuries between US combat forces and civilian casualties (Fig. 52-7).
FIGURE 52-6 Typical distribution of protective body armor for US forces.
FIGURE 52-7 Comparative distribution of injuries between US soldiers (protected body armor) and civilians.
Due to the evolution of the IEDs, the military has adopted increasing emphasis on protective strategies for both individual personnel and vehicles. In previous conflicts, antipersonnel devices were limited in explosive power in order to create a maiming injury that incapacitated the individual and diverted resources to care of the injured soldier (medic/litter bearers). The continued evolution of the IED (and its more devastating relative, the explosive fused projectile [EFP]) has created an increasingly powerful and destructive weapon. The scope of energy and injury of these devices is unlike that encountered in any other setting. Examples of the force of these devices and wounding patterns are depicted in Figs. 52-8 to 52-12.
FIGURE 52-8 IED explosion near Humvee.
FIGURE 52-9 IED explosion underneath mine-resistant/ambush-protected vehicle (MRAP).
FIGURE 52-10 Heavily damaged MRAP after IED explosion (note passenger hull largely intact).
FIGURE 52-11 Typical high-energy thermal and penetrating injury secondary to IED.
FIGURE 52-12 Typical multiple penetrating fragmentary injuries from IED (note relative sparing of trunk secondary to body armor).
The IEDs are ingenious and available at relatively small cost. Military artillery rounds are commonly used in series or clusters combined with simple but effective triggering mechanisms including cell phones, garage door openers, and timing clocks. Recent tactics employed by the enemy insurgents include incapacitation of a primary vehicle through the use of an initially triggered IED. As the vehicle survivors dismount or on the arrival of reinforcements, a second or third IED is detonated in the same region. In addition, snipers are at the ready to target the dismounted soldiers and have learned to target gaps in body armor that include the sides of the torso, the neck, the lower back, and the groin. High-velocity sniper rounds are capable of penetrating the standard Kevlar helmet, and the subsequent cranial injury proves devastating.
Explosive devices may also be loaded into vehicles (vehicle-borne improvised explosive device [VBIED]) and are capable of transmitting enormous, lethal, and widespread damage. Suicide improvised explosive devices (SIEDs) prove to be particularly hard to detect and defeat among large urban populations as freedom of access and movement increases during the postconflict phase.
Continued experience with IEDs and the newer EFPs has driven a continued evolution of larger vehicles collectively referred to as mine-resistant/ambush-protected vehicles (MRAPs). Increasing efforts are being directed to improve the interior cabin design of these vehicles to mitigate indirect injuries such as lumbar spine injuries from seat or blast impact. Interior design is also meant to limit secondary strike injuries as soldiers are thrown about the interior of the vehicle following a blast. General design features of these vehicles include elevated, V-shaped hulls to deflect blast injuries and devices to defeat the IED (Figs. 52-13 and 52-14).
FIGURE 52-13 Exterior appearance of Mine Resistant Ambush Protected (MRAP) personnel carrier.
FIGURE 52-14 Demonstration of energy-displacing effects of typical MRAP hull.
Specifics of wounding and wound care management will be discussed in greater detail later in this chapter. The importance of recognition of the energy and highly variable pattern of distribution of these wounds cannot be overemphasized.
FIELD CARE
Ensuring the survival of the wounded soldier begins at the point of wounding. In the decades following the Vietnam War, the military field medic was schooled in the basics of prehospital care, as though the principles of civilian and urban trauma care were equally applicable to the tactical combat situation. The sobering encounters during Mogadishu (“Black Hawk Down”) as well as other Special Forces encounters highlighted the flawed logic and often lethal consequences of this assumption. The Special Forces medical community recognized that good medicine could lead to bad military tactics, and, in turn, bad military tactics resulted in casualties and mission failure. As a result of this recognition and through the leadership of such individuals as Captain Frank Butler (US Navy, Retired), the standards of military field care were examined and completely restructured and revised.4 The Committee on Tactical Combat Casualty Care (CoTCCC) was formed in 2002 and serves today as the military’s premier source of information and leadership for the prehospital care arena. The CoTCCC consists of civilian and military medical providers (officers, enlisted personnel, Special Forces, and civilian medical experts) (Fig. 52-15). The Committee continually reviews the current evidence-based material regarding casualty care in the field and makes recommendations that are applicable to the military medic. The most current set of recommendations is published as a portion of the Pre-Hospital Trauma Life Support Manual as well as a freestanding version known as the military edition (Elsevier Publishers, 7th ed.) (Fig. 52-16).
FIGURE 52-15 The logo of the Committee on Tactical Combat Casualty Care. (Reproduced with permission of the Committee on Tactical Combat Casualty Care (coTCCC). Copyright © coTCCC. All rights reserved.)
FIGURE 52-16 The military edition of Pre-Hospital Trauma Life Support (PHTLS), which contains the current guidelines of the Committee on Tactical Combat Casualty Care. (Reproduced with permission from Committee on Tactical Combat Casualty Care. Pre-Hospital Trauma Life Support—Military Edition. St. Louis: Mosby-Elsevier; 2007, © Elsevier.)
The unique product of the CoTCCC is the division of prehospital field care during combat situations into three distinct phases referred to as:
1. Care under fire
2. Tactical field care
3. Tactical evacuation care (TACEVAC)
The interested reader is referred to the military edition of the Pre-Hospital Trauma Life Support Manual for a detailed description of these recommendations (summarized in Table 52-3). While many recommendations are similar to civilian care, there are also significant distinctions. The principles of care under fire emphasize the tactical necessity of defeating enemy fire while minimizing further casualties (soldier as well as medic). Tactical field care has embraced the use of tourniquets, hemostatic agents, and limited fluid resuscitation strategies based on recent evidence-based reviews. The section of TACEVAC incorporates principles of far-forward en route care while recognizing the limitations imposed by an austere environment.
TABLE 52-3 Summary Statement of Current Recommendations of the Committee on Tactical Combat Casualty Care
MILITARY MEDICAL CARE STRUCTURE
There are five basic levels of care in the military medical evacuation and care system (previously referred to as echelons). These levels are not to be confused with American College of Surgeons’ designation of US trauma centers (Table 52-4). Different levels of field care are intended to denote differences in resource capability, but not the quality of care. Each level has the capability of the level forward of it, and expands further upon that capability. Soldiers with injury or illness effectively treated at any level should be returned to duty at that level whenever possible. All other casualties are prepared for safe evacuation and subsequent transport to a higher echelon of care.
Level I. First aid and immediate lifesaving measures are delivered at the scene of wounding. Care is administered by the injured soldier himself (“self-aid and buddy aid”), a combat lifesaver, or a combat medic or corpsman. A combat lifesaver is trained in basic first aid, while a combat medic or corpsman is trained as an emergency medical technician-basic. The most forward medical facility available is a BAS. These facilities may be located in a tent or in any other opportune structure. These facilities are capable of performing treatment and triage. Typically, the highest level of medical provider at a BAS is a physician assistant or a nonsurgical physician. The function of the BAS will be to treat and evacuate or to return the casualty to duty as appropriate to the level of injury. The BAS has extremely limited holding capability of 6 hours or less.
Level IIA. Medical Company. Generally, these are somewhat larger facilities ranging from 20 to 50 personnel. They have limited inpatient bed space and can hold or treat casualties for up to 72 hours. The services that are available at this level include primary care (sick call), as well as dental care. Usual ancillary services include laboratory and x-ray capability. Some of these facilities have optometry and psychiatry services on an intermittent basis. Each military service has a slightly different unit designation at this level. This level does not offer routine surgical capability but may be able to offer lifesaving interventions such as endotracheal intubation and placement of chest thoracostomy tubes.
Level IIB. The medical company or BAS may be augmented with surgical capability. If this is the case, the designation of this facility becomes Level IIB. The Army provides this supplementation in the form of a forward surgical team (FST—20-member team) (Fig. 52-1). The Navy provides surgical capability via a forward resuscitative and surgical system (FRSS—eight-member team). The Air Force’s concept utilizes a five-member team referred to as a Mobile Field Surgical Team (MFST). Each of these military medical units is designed to provide basic capabilities of resuscitative surgery. Using these building blocks, these highly mobile teams can typically provide one to two operating room tables within 30–60 minutes of advancement. They can be set up in a mobile environment, climate-controlled tents, or shelters of opportunity. These teams carry enough equipment and supplies to perform somewhere between 10 and 40 life-stabilizing operations. While designed for 24–72 hours of continuous operations without resupply, these teams may be employed in a nonconventional configuration and provide ongoing support to small maneuvering elements if they have the opportunity for adequate resupply. A comparative summary of capabilities and requirements for these surgical augmentation teams is provided (Table 52-5). These facilities do not usually have significant holding capability, and rely on a capable and robust en route evacuation and care system in order to maintain their surgical volume.
TABLE 52-5 Definition of Level IIB Surgical Augmentation Teams
Level III. This level represents the highest level of medical care available within the combat theater of operations. Usually the largest bulk of inpatient beds within a combat theater are located at Level III facilities. Most deployable hospitals are modular in nature, allowing the commander to tailor the medical response to the expected or actual demand. These hospitals may be set up in a mobile fashion, but may also use buildings such as churches or abandoned hospitals if such opportunities are available. The Army’s nomenclature for these units is the combat support hospital (CSH), which has replaced the historic MASH unit. The Navy has the fleet hospital, which is now termed Expeditionary Medical Unit (EMU), and the Air Force the Expeditionary Medical Support (EMEDS) system. The difference in capability between the Level II and III facilities is that they have subspecialty care available and other services to typically include computerized tomography and increased blood bank and laboratory capability (Figs. 52-17 and 52-18).
FIGURE 52-17 The Level III medical facility at Craig Joint Theater Hospital, Bagram, Afghanistan.
FIGURE 52-18 An aerial depiction of the Level III medical facility at the 332nd Air Force Theater Hospital Balad, Iraq.
Current doctrine maintains full holding and recovery capability at Level III facilities. The length of time that US casualties are held at a Level III facility has dramatically changed during this current conflict as the result of the introduction of a capable and robust en route care system. In previous conflicts, casualties recovered at the Level III facilities until they were very stable and essentially ambulatory. The fluidity of medical support for an asymmetrical battle space, as well as the deployment of far-FSTs, has driven the development of an equally capable evacuation system. In response to the need, and in recognition of other shortcomings, the US Air Force developed and subsequently deployed Critical Care Air Transport Teams (CCATT) to fulfill this need. A CCATT consists of an intensivist physician, a critical care nurse, and a respiratory therapist (Table 52-6). The role of a CCATT is to provide continuous en route, high-intensity care from far-forward austere locations to more rearward (more capable and resource abundant) facilities. As a result of the deployment of CCATT, the average duration that a current casualty is in theater is less than 48 hours (including one to two stabilizing surgery procedures). The role of the CCATT and the en route care system will be discussed later in this chapter.
TABLE 52-6 Composition of Three-Member CCAT Team Description
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