Jay Johannigman, Peter Rhee, Donald Jenkins, and John B. Holcomb
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.
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.
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.
TABLE 52-4 Echelons 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
Level IV. Level IV facilities represent the larger, more capable military hospitals outside of the theater of combat. These hospitals may be located in Europe or the United States. Although the three services have many hospitals worldwide, only a few select hospitals receive casualties from the war. The Landstuhl Regional Medical Center (LRMC) is the hub for all casualties being transported from the southwest Asia theaters of Iraq and Afghanistan. This facility is jointly manned by members of the US Army, Navy, and Air Force medical corps. The LRMC has been verified as meeting the criterion of a Level II trauma facility by the American College of Surgeons Committee on Trauma. It is the first facility outside of the CONUS to receive this designation.5
Level V. These facilities represent the zone of the interior, CONUS-based hospitals outside the combat zone. These facilities include military medical centers, other federal hospitals (Veterans Affairs hospitals), and civilian contracted hospitals. These facilities represent the most definitive care possible and include burn care, long-term convalescence, and specialized rehabilitation.
OVERVIEW OF MOVEMENT OF PATIENTS
The distribution and triage destination of casualties from the forward edge of the battle zone can be a complex and varying discussion. As with civilian trauma systems, the ideal situation is to provide an integrated spoke-and-hub trauma system that matches the patient’s needs to the facility’s resources. The complexity of this process is multiplied by considerations of lines of battle, maturity of the theater and medical facilities, and the evacuation capability within the theater. Continual evaluation of appropriate patient movement, triage, and flow is an absolute imperative. The current conflict is the first opportunity for the military medical corps to evaluate the effectiveness of this process utilizing a trauma systems approach. The military has looked to the American College of Surgeons Committee on Trauma and the greater than 30 years of trauma systems experience as a model to evaluate its own efficacy. A discussion of trauma system development as it applies to the current military medical system will be considered later in this chapter (see Section “Military Trauma Systems”).
COMBAT CASUALTY CARE
It is an appropriate (but sad) truism that the conduct of war advances the science of trauma care. The conflicts of Operation Enduring Freedom and Operation Iraqi Freedom have resulted in a wide spectrum of changes to our thought processes as well as to the clinical practice in care of the injured patient. In some instances innovations have occurred by remembering lessons from the past. Other advances have resulted from new insights derived from the experience of managing a significant volume of severely injured casualties. The following section will describe some of the innovations brought from the battlefield to advance the care of the injured patient.
Prehospital Care Advances
As described previously, the CoTCCC has taken the lead in defining and shaping the practice guidelines for combat casualty care in the field. In the process of defining care during the three time frames of field care (care under fire, tactical field care, and TACEVAC), the CoTCCC has reshaped many principles.
Fluid Resuscitation. The CoTCCC currently recommends a strategy of “permissive hypotension” for the management of combat casualties with penetrating injuries. This conclusion is based on a growing wealth of evidence that suggests that restoration of blood pressure prior to surgical hemorrhage control leads to adverse outcomes as well as increased mortality.6–8 There is no evidence to support the notion that prehospital fluids offer a survival advantage—despite years of dogma insisting on their use.9 The strategy of permissive hypotension stresses external hemorrhage control (as possible) with judicious monitoring of the patient to include intact mentation or the presence of a palpable peripheral pulse. Resuscitation of blood pressure is deferred until the casualty is in an environment where definitive hemorrhage control may be obtained. This strategy relieves the burden of additional or accelerated blood loss and ongoing hemorrhage control in the field where IV fluids are difficult to carry and, in fact, may negatively influence outcomes.
Clinical practice in Vietnam advocated the early and aggressive use of crystalloid resuscitation. This practice may have been in part a consequence of the misinterpretation of early resuscitation literature that discussed the use of crystalloid fluids (until whole blood was available).10 The clinical practice of aggressive crystalloid resuscitation was translated back to the civilian sector and became integrated as a fundamental tenet of the Advanced Trauma Life Support (ATLS) course over the next 30 years.11 Recent basic scientific research has challenged the wisdom of the use of crystalloid solutions by demonstrating adverse immunological consequences following their use.12 Lactated Ringer’s solution was initially developed with both racemic forms of lactate (D and L isomers of lactate). Research has suggested that the elimination of the D isomer may be beneficial.13 An additional detriment of crystalloid resuscitation (normal saline or Ringer’s lactated solution) is that it adversely contributes to systemic acidosis via the intrinsically low pH of these solutions (5.0 and 6.5, respectively).
The choice of fluid to be used in the military field setting has also changed. The CoTCCC recommends the use of small-volume colloid solutions. These solutions can achieve similar clinical volume expansion benefits while reducing the clinical weight and volume of material that must be carried forward in the medic’s backpack.14
The current recommendation of the CoTCCC has been to obtain IV access (heparin lock) on all casualties. Fluid administration is withheld unless the casualty demonstrates loss of consciousness or loss of palpable peripheral pulses. Fluid resuscitation consists of a 500 cm3 bolus of a colloid solution (Hextend), and this may be repeated one time. Oral hydration of the casualty is permissible. Traditional civilian care tenets have maintained the patient in an NPO status for fear of aspiration at the time of future surgical intervention. The military system accepts this minimal risk and acknowledges that all urgent operations must assume a full stomach (from previous meals) at the time of induction of anesthesia. The use of oral hydration of casualties accommodates for care in the situations where evacuation may be delayed hours or even days secondary to tactical considerations.
Tourniquets. The use of tourniquets is depicted in ancient Greek literature and their presence on the battlefield has been a constant in military medicine since that time. Hemorrhage from extremity injuries has been recognized in wars throughout history as the leading cause of potentially preventable deaths. Autopsy findings from the earliest portion of this conflict have confirmed this finding.15 Widespread endorsement of the use of tourniquets has been tempered by anecdotal literature reports and current dogma that suggests that the risk of tourniquet use (limb ischemia, pressure necrosis, etc.) outweighs the potential benefits of their use. Historically, in the US Civil War, the Spanish Civil War, and World War I, tourniquets were employed but lost favor due to their mechanical and perceived clinical ineffectiveness. The ineffectual strap-and-buckle tourniquet that was a standard issue in the US military for the last five decades may have accounted for this perception. With recent insights, a coherent move to a better designed tourniquet on the battlefield has occurred. The pertinent issues include the use of tourniquets in patients at risk of lethal exsanguination, improved tourniquet science and design, appropriate training and doctrine, and documentation of clinical research and experience (Fig. 52-19).
FIGURE 52-19 The combat application tourniquet.
Kragh et al. recently published what proved to be the most extensive review of tourniquet use in a combat setting.16,17 This study examined a cadre of 232 patients who had 428 tourniquets applied to 309 injured limbs. The study demonstrated an acceptably low major complication rate (less than 3%) as well a positive risk/benefit ratio in terms of survival. In a subsequent follow-on study, the same group demonstrated a statistically significant survival benefit when tourniquets were applied in the field and prior to the onset of shock (loss of peripheral pulses). The results forwarded from the current combat operations as well as the institution of appropriate practice guidelines have resulted in tourniquets being advocated as a fundamental care process by the CoTCCC and by all military medical commands. The addition of tourniquets to standard equipment sets for civilian ambulance services in the United States will become recommended practice as of 2012. The most common form of tourniquet adopted by the US military is depicted in Fig. 52-19.
The subject of topical hemostatics is an exciting and progressively evolving area of interest that is rapidly being translated from combat care to the civilian arena. The high incidence of extremity injury in a combat setting is a result of the increased use and effectiveness of body armor. This reality is combined with the sobering fact that perhaps one third of all preventable combat deaths are the result of potentially compressible hemorrhage of the extremities. This had led to renewed interest in hemorrhage control techniques. The use of tourniquets was previously described. The incorporation of topical hemostatics (combined with the appropriate use of tourniquets) is seen as a key component of this innovative process. A plethora of agents have been forwarded by multiple manufacturers in response to the significant interest and focus placed on this topic by the military medical corps. The lead agency for review process has been the CoTCCC. The CoTCCC reviews the available peer-reviewed literature as well as evidence forwarded from the US Army Institute of Surgical Research and its standardized hemorrhage control model. As a result of the most recent recommendation, the CoTCCC guidelines were changed to recommend Combat Gauze© as the first-line treatment for life-threatening hemorrhage that is not amenable to tourniquet placement (Fig. 52-20).18 Combat Gauze© offers the medic the advantage of being a gauze-type (malleable) agent rather than a granular agent. Strong preference was voiced by combat medics for a gauze-type agent rather than a powder or granule. This was based on the experience in combat that powder or granular agents do not work well in wounds where the bleeding vessel is at the bottom of a deep and narrow wound tract. A gauze-type hemostatic agent has been found to be more easily applied in this setting. Combat Gauze© should be applied with 3 minutes of sustained direct pressure over the bleeding site in order to be effective. Simply applying the agents without maintaining pressure is not adequate. After 3 minutes of direct manual pressure, a pressure dressing may be applied over the wound to cover the wound and the agent as well as to maintain a degree of pressure.
FIGURE 52-20 QuikClot Combat Gauze©.
Damage Control Resuscitation
Perhaps the most significant contribution of the current conflict to our understanding of care of the injured patient is the restructuring of the approach to the patient with major hemorrhage. The significant military experience gained over the past decade of armed conflict has created a paradigm shift in the management of the patient requiring massive transfusion (defined as transfusion of greater than 10 U of packed red blood cells [RBCs] in a 24-hour period). Collectively, this approach has been coalesced under the term damage control resuscitation (DCR). DCR is appropriately considered a comprehensive approach to the patient with major traumatic injury and life-threatening hemorrhage. It consists of multiple, ongoing, horizontally based resuscitation principles including:
1. Recognition of the patient at risk
2. Permissive hypotension
3. Immediate institution of hemostatic resuscitation
4. Damage control surgical principles
RECOGNITION OF THE PATIENT AT RISK
Traditional trauma principles have emphasized recognition of trauma patients at risk of adverse outcomes by a definition of shock based on parameters of pulse, blood pressure, and urinary output (ATLS). Extensive experience with significant numbers of young combat casualties has led to the conclusion that awaiting the onset of abnormalities of blood pressure, pulse, and urinary output creates significant and often life-threatening delay in recognition of patients who are in distress. The current emphasis has been realigned to early detection and avoidance of the components of the so-called lethal triangle or triad of death. The presence of acidosis, hypothermia, and coagulopathy (Fig. 52-21) following traumatic injury significantly alters outcome and increases the risk of mortality.19 Review of combat wounding data at the time of the presentation of a casualty to the surgical field hospital has led to the description of key “trigger points.” Each of these trigger points is associated with statistically significant outcome differences in the trauma patient. These trigger points may be readily identified within the first 5 minutes of care. Additionally, these trigger points may be reliably identified in combat casualties long before the so-called traditional shock parameters appear. These five trigger points consist of the following parameters and will be discussed sequentially:
1. Acidosis as manifested by a base deficit greater than 6
2. Coagulopathy (INR greater than 1.5)
3. Hypothermia (temperature less than 96°)
4. Systolic hypotension at presentation (blood pressure less than 90 mm Hg)
5. Hemoglobin value of less than 11 g
FIGURE 52-21 The lethal triad.
The presence of systemic acidosis, defined as a base deficit of greater than 6, can be rapidly identified in the first minutes following the arrival of the combat casualty (or civilian trauma victim). A base deficit of greater than 6 in trauma patients is associated with a demonstrated increased transfusion requirement,20 a longer ICU stay,21 and increased occurrence of massive transfusion as well as an increased patient mortality rate.22 The presence of a base deficit is detectable long before blood pressure drops and is indicative of systemic cellular hypoxia. Acidosis contributes to coagulopathy more than any other factor due to the negative impact on the function of the clotting cascade.23
The presence of coagulopathy in the trauma bay identifies a cohort of patients at increased risk of death. This association was originally described in a civilian population.19 Through evaluation of data in the JTTR, this same association has also been demonstrated to have an exponential impact on mortality (Fig. 52-22).24 The presence of coagulopathy is a part of the lethal triad, and its rapid correction following identification will be discussed below.
FIGURE 52-22 The relationship between initial INR in the ED and subsequent mortality. (Reproduced with permission from Niles SE, McLaughlin DF, Perkins JG, et al. Increased mortality associated with the early coagulopathy of trauma in combat casualties. J Trauma. 2008;64(6):1459.)
The presence of hypothermia, defined as a core temperature of less than 96°, is the third arm of the lethal triad. Hypothermia can be detected at the time of arrival of the trauma patient. A temperature less than 96° is associated with increased mortality as well as increasing the intrinsic dysfunction of the clotting cascade.25 Coagulation disorders are associated with temperature-related deficits in clotting factor enzyme function, platelet aggregation function, and fibrinolytic activity.26 These series of enzymatic reactions of the coagulation cascade are strongly inhibited by hypothermia.
It is difficult to ascertain how the so-called critical threshold of hypotension was initially established as 90 mm Hg. Previous experience has demonstrated that blood pressure measurements early in the course of shock are not well correlated with blood flow or cardiac output. Significant tissue hypoperfusion is demonstrated in hypovolemic laboratory models as well as in blunt and penetrating trauma patients. This observation is valid despite normal vital signs. The demonstration of a “normal blood pressure” following trauma may be particularly deceptive in young, previously healthy patients. Eastridge et al. examined the records of over 850,000 trauma patients entered into the National Trauma Database with respect to the initial presenting blood pressure.27 This study revealed that at 110 mm Hg, the slope of the mortality curve increased such that mortality was 5% greater for every 10 mm Hg detriment in systolic blood pressure (Fig. 52-23). The conclusion of this group was that a systolic blood pressure less than 110 mm Hg is a more clinically relevant definition of hypotension and hypoperfusion than the current standard of 90 mm Hg.
FIGURE 52-23 Relationship between initial systolic blood pressure and mortality based on age (upper) and gender (lower). (Reproduced with permission from Eastridge BJ, Salinas J, McManus JG, et al. Hypotension begins at 110 mm Hg: redefining ‘hypotension’ with data. J Trauma. 2007;63:291.)
Hemoglobin Less Than 11
Early hemoglobin measurements obtained within minutes of patient arrival in the emergency room are a reliable indicator of ongoing hemorrhage. Early hemoglobin levels are significantly lower in patients who require emergent intervention(s) to control hemorrhage.28
Studies from the JTTR and other sources are continuing to define the predictive value of these “trigger points” with respect to the need for massive transfusion. Through analysis of 680 massively transfused combat patients, the relationship appears to be progressive and linear (Fig. 52-24).29 The absolute precision, specificity, and sensitivity remain to be determined.
FIGURE 52-24 Risk of undergoing massive transfusion based on number of positive “trigger points” in the emergency room. (Reproduced with permission from McLaughlin DF, Niles SE, Salinas J, et al. A predictive model for massive transfusion in combat casualty patients. J Trauma. 2008;64:S57.)
Diagnosis Done—Damage Control Resuscitation
Once a patient at increased risk for blood loss, blood transfusion, or massive transfusion is identified, it is of value to develop a strategy recently coined as “DCR.” DCR consists of a 3-fold approach adopted by military medics as a result of significant experience with gravely injured, penetrating trauma patients. The first step is early recognition by use of clinical judgment, injury pattern recognition, and the trigger points discussed above. The second arm of DCR is to employ permissive hypotension until definitive surgery and hemorrhage intervention is established. The third arm is to employ a modified field resuscitation guideline that eliminates the use of excessive crystalloid fluids while infusing blood, plasma, and platelets in a balanced ratio of 1 U packed RBCs to 1 U of plasma to 1 U of platelets. The intent of this third arm is to initiate early and immediate restoration of a competent coagulation cascade as soon as the high-risk patient is identified in the trauma bay. To coin a famous phrase: “it is better to stay out of trouble than to get out of trouble.”
Hypotensive resuscitation has been a respected portion of military medicine since at least the First World War. Walter Cannon, MD, described the utility of this strategy as early as 1916. Permissive or hypotensive resuscitation was again highlighted by Edward Churchill, MD, during the Second World War. Since that time, there have been numerous basic science publications as well as clinical series that have demonstrated the utility and survival advantage of judicious resuscitation prior to definitive hemorrhage control.30–32 The benefit of prehospital or presurgical crystalloid infusion has never been demonstrated. Further studies will be required to fully elucidate the degree and duration to which permissive hypotension may be productively carried out. It is also important to note that permissive hypotension in the combat setting takes full advantage of the young and robust physiologic reserve of the injured soldier. It remains to be determined whether this principle may be equally applied to the more diverse (older) civilian population with varying mechanisms of injury.
The third, and final, arm of DCR is the employment of a fluid resuscitation strategy that immediately focuses attention on correcting the lethal triad (acidosis, coagulopathy, and hypothermia). During the early phase of OIF/OEF, the majority of field hospitals developed a resuscitation strategy that paired aggressive use of plasma with implementation of whole blood transfusions. This was at first a practical necessity since platelet components could not be forwarded to the far-forward field locations. Early transfusion of whole blood from volunteer (military) donors proved to be a pragmatic and dramatically effective solution to restoration of both blood volume and a competent clotting cascade. Plasma was used liberally during resuscitation as a result of its favorable pH balance as compared with the relative acidity of normal saline or Ringer’s lactate.
Perhaps one of the most important papers to be published from the conflict is the work of Borgman et al.33 This study analyzed the survival outcomes of combat casualties who required a massive transfusion at the two large CSHs located in Iraq. This is a group of interest since previous military and civilian work has demonstrated that patients requiring a massive transfusion have a mortality rate as high as 40%. This study group analyzed survival based on the relative ratio of plasma infused with respect to units of packed RBCs transfused (Fig. 52-25). The analysis demonstrated a dramatic and statistically significant reduction of mortality the closer the transfusion ratio approximated 1:1. This observation is dramatically different than the traditional resuscitation strategy advocated by ATLS, which includes initial crystalloid resuscitation of 2 L followed by the sequential administration of 6 U of packed RBCs and thenfresh frozen plasma followed by more crystalloid solution.
FIGURE 52-25 Mortality ratio(s) based on relative ratio of plasma to units of PRBCs administered. (Reproduced with permission from Borgman MA, Spinella PC, Perkins JG, et al. The ratio of blood products transfused affects mortality in patients receiving massive transfusions at a combat support hospital. J Trauma. 2007;63:805.)
Since Borgman’s original work, there have been numerous additional publications from both civilian and military data sources that appear to confirm this same observation.34–37 In a large retrospective civilian sector publication,38the outcome of massively transfused trauma patients across 25 trauma centers was measured and was consistent with this same finding. At the time of this writing, the results of a definitive, prospective observational trial are currently being collated as the prospective outcome measurement(s) for massively transfused trauma patients (PROMTTT) trial. This effort will prospectively catalog the time course, sequence, and resultant outcome of blood and blood product administration across 450 patients at 10 major US trauma facilities.
Recent publications have also examined the impact of a 1:1 ratio of PRBCs to platelets. In a fashion similar to the data presented above, there is growing evidence of a survival benefit for patients requiring massive transfusion secondary to hemorrhagic shock if the platelet to PRBC ratio is equalized.39,40 Thus, the current clinical practice guideline (CPG) for DCR in the theater for patients requiring massive transfusion is to establish a 1:1:1 (PRBCs:plasma:platelets) ratio of fresh products wherever possible.
The approach to transfusion of the combat-injured patient has evolved continually since it was first introduced during World War I. The evolutionary process has included whole blood, modified whole blood, and, finally, the current use of component therapy.41,42 Component therapy was developed following the Korean War in the attempt to more effectively transport and store RBCs harvested in the United States that were destined for use in combat zone(s) overseas (Vietnam). During this era (1950s to 1960s) modified whole blood was stored up to 3 weeks. Logistical and transport considerations created enormous difficulties in the timely delivery and maintenance of whole blood products to the theater of operations. During the Korean conflict it was estimated that as much as 70% of all blood products shipped to this conflict were subsequently discarded secondary to aging expiration. This change to component therapy took place without evidence comparing the benefits, risk, or efficacy of these products (components) with the predecessor agent (whole blood). Current “classic” transfusion guidelines regarding indications for blood component therapy are based on expert opinion, experiments in euvolemic patients undergoing elective surgery, and modified whole blood that is no longer commonly available.43,44 In addition, the storage of RBCs has progressively increased over time to the current limit of 42 days without the appropriate prospective evaluation of the impact of increased storage time on the critically ill patient.
Recently there has been a shift in opinion by a portion of the trauma community regarding the transfusion approach to hemorrhagic shock. The concept of DCR as the optimal approach for the treatment of patients with life-threatening hemorrhagic injuries is gaining increasing acceptance as a result of the published experience from the battlefield. The use of warm fresh whole blood (WFWB) has also been utilized in US military combat support facilities. This practice pattern was adopted as a pragmatic solution to maintaining the principles of DCR in the austere setting where banked blood and component therapy principles were not applicable due to logistical and transport considerations.45 A recent review describes the transfusion of over 6,000 U of WFWB during combat operations.46 The recent large scale use of WFWB by the US military has rekindled interest in its use for patients at high risk of death from hemorrhage.47
Theoretically, WFWB may be advantageous as compared with component therapy in patients with hemorrhagic shock. This may reflect the improved function of RBCs, plasma, and platelets in WFWB as well as the avoidance of the adverse effects of the storage lesions when older RBCs or plasma are transfused.48–50 The assessment of the risks and benefits of the transfusion of either WFWB or component therapy (especially when RBCs of advanced storage age are transfused) must be balanced in perspective to the high mortality rate for patients with traumatic hemorrhagic shock and massive transfusion. This balance is impacted by the severity of illness and injury as well as the age of the patient. In patients who do not have life-threatening bleeding the risks of WFWB may outweigh the potential benefit. Conversely, for patients with traumatic hemorrhagic shock it may be the case that the survival advantage provided by WFWB outweighs the risk, especially if the alternative approach includes significantly aged RBCs. A growing body of literature has demonstrated that aged RBCs may pose a significant liability with respect to the inflammatory and vascular modulation cascade(s).48
An additional concern with the utilization of component therapy in the setting of hemorrhagic shock and massive transfusion is the increased volume of anticoagulants and additives that are delivered by component therapy. The process of distributing and separating the components from a single unit of whole blood results in the addition of approximately 280 cm3 of anticoagulant solutions to every initial 500 mL of whole blood. This represents a dilution of approximately 40% (compared with WFWB) in addition to providing factors that directly impede the coagulation process (citrate).47 This observation may explain the observed increased risk of dilutional coagulopathy and significant anticoagulation observed in patients with hemorrhagic shock who receive significant volumes of component therapy. As future studies are designed, it will be imperative to account and assay for the anticoagulants and volume contributed by the component separation process.
A third potential mechanism to explain the striking difference seen with the use of WFWB in combat casualties is the use of fresh blood product versus old blood product. Logistical constraints and transport issues in a combat zone impede the delivery of blood products to the far-forward theater facilities. The median storage age of RBCs transfused in Iraq (during the first 5 years of the conflict) was 33 days. This is not entirely dissimilar to the average storage age of 21 days reported in the United States. A recently published series of coronary artery bypass graft patients examined the effect of transfused blood on outcome.51 Patients who were given older units had a higher rate of in-hospital mortality, intubation beyond 72 hours, renal failure, and sepsis. A composite complication was more common in patients given older blood and at 1 year mortality was significantly less in patients given newer blood. As a result of a concerted quality improvement effort, the current average age of blood components transfused during Operation Enduring Freedom is now 23 days.
In summary, the modern-day battlefield concepts of resuscitation of the severely injured patient include early recognition, avoidance of the lethal triad, permissive hypotension, and aggressive resuscitation of the hemostatic properties of blood through a 1:1:1 approach. This strategy emphasizes staying out of trouble rather than getting out of trouble. There is a significant wealth of interest from both the civilian and military trauma care communities actively pursuing further information in this area.
EN ROUTE CARE
This chapter has highlighted the changes implemented by military medicine to provide far-forward surgical capability and simultaneously employ an operative strategy of damage control—rapidly stabilize and then evacuate. The success of this strategy relies on the concomitant evolution of a timely and rapid evacuation system capable of transporting stabilized (but not necessarily stable) patients. This transport must occur without interruption in the intensity or quality of life-sustaining support. By doctrine, the US Air Force is responsible for the transport (evacuation) of all casualties from forward surgical facilities. The solution to this care need was the creation of CCATT by the USAF. A CCATT consists of an internist physician (surgeon, anesthesiologist, pulmonologist, or emergency medicine), an ICU nurse, and a respiratory therapist. Each team is self-contained and capable of supporting up to six critically ill patients (three of whom may be intubated) for a period of 12–24 hours. A CCATT is capable of moving forward to an austere setting and assuming the task of ongoing critical care and resuscitation while escorting the patients to a more secured, robust facility. The transport may take place from a remote forward surgical company to a Level III theater hospital, from a theater hospital (Iraq or Afghanistan) to Germany, or from Germany to the United States. A CCATT equipment set consists of small, lightweight transport ventilators, vital signs monitors, handheld blood analyzers, and a myriad of other hardware and medical supplies to support this mission (Figs. 52-26 and 52-27). A current focus of USAF research is to improve equipment capabilities as well as algorithms of care. During the current conflict, it is estimated that over 4,000 CCATT missions have been accomplished with a mortality rate of less than 1%.52
FIGURE 52-26 A Critical Care Aeromedical Transport Team (CCATT) preparing a casualty for evacuation onboard a C-17 cargo aircraft.
FIGURE 52-27 A CCATT patient with portable transport equipment configured for movement.
DAMAGE CONTROL SURGERY PRINCIPLES
The principles of DCR are complemented by a surgical operative technique collectively termed damage control surgery. This concept (first forwarded by Rotondo et al.53) has been taken to an entirely new level during this conflict. The military experience has demonstrated that this technique is amazingly effective even when integrated across an entire theater trauma system. Far-FSTs (Army FST, Navy FRSS, or Air Force MFST) leverage the opportunity to stop exsanguinating hemorrhage, secure the airway, restore peripheral perfusion via shunts, and pack cavity wounds with hemostatic agents. Resuscitation employs early use of whole blood (as necessary) to initiate restoration of the coagulation cascade. The far-forward team completes only that which is necessary to stabilize and then rapidly moves the patient to the next (higher) echelon of care. In turn, the next level facility may conduct further resuscitation surgery or “washouts” prior to preparing the patient for transport to the Level IV facility at LRMC. Each team along the way adapts an approach of “trust no one, check everything” and in turn understand that these patients (and their work) will be rechecked by the next team further up the chain. With continued experience and maturation, this process has proven dramatically capable. It is an appropriate testimony to the effectiveness of this system that the average duration that a casualty is in theater (including one to two damage control operations) is less than 48 hours.
Celiotomy in the combat setting requires speed and experience. Tactical damage control surgery is not a specific procedure, but refers to a state of mind. As opposed to civilian damage control surgery, tactical damage control surgery is somewhat different. In civilian terminology, it refers to an abbreviated operation due to physiologic exhaustion. In the military setting, damage control takes into account the tactical scenario, the resources available, the likelihood of further casualties, and best treatment options while leveraging the understanding that the casualty (in most instances) will be rapidly evacuated to a higher level of care. Speed and efficiency during the operative procedure is vital. There will be circumstances where simple reconstruction should be deferred to the next echelon of care (i.e., bowel anastomosis) in order to prepare for other casualties or to take advantage of evacuation flights of opportunity. There will be other scenarios where more definitive intervention is indicated, even in a far-forward setting. Vascular shunting is such an example. In the presence of arterial injury and distal limb ischemia, the placement of a temporary shunt is an effective, timely, and straightforward surgical procedure that converts a cold/ischemic limb into a perfused extremity that will remain viable during the process of evacuation to a higher level of care (Fig. 52-28).
FIGURE 52-28 Example of temporary vascular shunt in the superficial femoral artery.
Significant experience has been gained with the use of temporary intravascular shunts and they have proven to be particularly effective at saving lives and limbs.54 With transected vessels, shunting the artery and/or vein should be the initial approach. This can, and should be, completed rapidly with a minimum of surrounding dissection. The shunt is maintained in place with simple ligatures around the shunt and vessel at both the proximal and distal limbs. Once shunted, a decision may be made (based on tactical considerations and professional qualifications) regarding definitive repair. If appropriate resources and personnel are available, the vessel may be repaired at this same setting. If concomitant injuries and/or tactical considerations dictate that repair is deferred to a later time, the casualty may be managed or evacuated with the shunt remaining in situ. In either case (shunted or definitive repair) a complete four-compartment lower extremity fasciotomy is strongly encouraged for all casualties who have had any period of distal ischemia. The necessity of complete (full skin incisions) fasciotomy is another primary lesson learned during this conflict. Most deployed military surgeons predicate the need for fasciotomy on prior experience from the civilian experience with older patients with preexisting vasculopathies. The resultant reperfusion edema that may occur in the civilian setting (older patient, long-standing ischemia with atrophic distal musculature) is vastly different than that encountered in the combat zone. In the military setting the management of young, muscular soldiers who have experienced vascular ischemia requires recognition of the significant swelling and edema that occurs as a result of the primary injury (blast effect, cavitation injury, etc.) or the massive reperfusion edema that follows in these young patients with (previously) healthy muscle.
Military experience with this strategy of vascular shunting has demonstrated that definitive repair may be deferred to a later time. The distal extremity remains perfused with a greater than 85% patency rate if a shunt is used in a proximal position of the arm or leg.55
DAMAGE CONTROL PACKING
In austere settings, the casualty will be most appropriately managed by an operative strategy of damage control surgery, packing, and rapid evacuation to a higher echelon of care. The primary operative goal is to detect and control sources of exsanguinating hemorrhage. Identification of vascular injuries and/or significant organ hemorrhage is the first priority. Definitive vascular injury control or shunting is achieved along with control of contamination. Rapid control of intestinal injuries is achieved by stapling, with proximal NG drainage. Definitive restoration of intestinal continuity is deferred to a later procedure. Solid organ hemorrhage is managed by resection (if possible) or by packing as appropriate with use of topical hemostatic agents. Damage control operative techniques are employed in close concert with DCR principles including aggressive resuscitation of the coagulation cascade. Rapid temporary abdominal closure may be achieved in any of a number of ways (Fig. 52-29) in anticipation of evacuation and reexploration at a higher level of care. During the evacuation and transport process, judicious monitoring of resuscitation parameters includes full restoration of the clotting cascade while maintaining a degree of permissive hypotension. Resuscitation end points include serum lactate and central venous oxygen saturation. Significant attention is directed to restoration and/or maintenance of core body temperature to avoid hypothermic coagulopathy.
FIGURE 52-29 Damage control temporary closure.
MILITARY TRAUMA SYSTEMS
The development of trauma care has always been a synergistic relationship between the military and the civilian sector. Dr Michael Debakey famously noted that wars have always promoted advances in trauma care because of the concentrated (and focused) exposure of military providers to large numbers of injured people over a relatively short span of time. Furthermore, wartime medical experience fosters an intense and fundamental desire to improve outcomes and standards of care on behalf of the soldier on the front lines. In Vietnam, lessons learned regarding aeromedical evacuation, field medical care, and resuscitation were rapidly incorporated into civilian paradigms and practice. At this same time (1966), the National Academy of Sciences published Accidental Death and Disability: The Neglected Disease of Modern Society. This publication cited civilian trauma in the United States as one of the most significant public health problems faced by the nation. The combination of battlefield medicine and the call to action by the National Academy prompted a concerted evaluation of trauma care. In 1976, the American College of Surgeons produced the first iteration of injury care guidelines entitled Optimal Resources for Care of the Injured Patient.56 This concept rapidly evolved into the development of formal, integrated networks of care known as trauma systems.
Trauma centers and trauma systems in the United States have had a remarkable impact on improving outcomes of injured patients and reduction of mortality. As the military medical corps prepared itself for the first Gulf War and subsequently the Global War on Terror, it was able to look to the American College of Surgeons and its Committee on Trauma for a template of trauma systems. The evolution of trauma systems would be a transformational step for military medicine as it faced the enormous challenge of coordinating care of the injured soldier across a diverse and asymmetrical landscape that featured combatants capable of moving in advance with lightning speed. These recent conflicts would also be the first where the majority of military medical providers had been afforded the opportunity to train in or work at US trauma systems participating in an organized system of care. The lessons and examples provided by civilian trauma systems in the United States from 1970 to 2000 served as an initial blueprint template on which the current generation of military medical providers could build.
Operation Desert Shield and Desert Storm (1991–1992) highlighted a number of issues in which the US military had fallen behind the successful construct fostered by civilian systems of injury care. Inadequacies were formally noted in both preparation and delivery of trauma care in the combat environment. In 1996, the Government Accountability Office (GAO) issued a report addressing shortfalls from Operation Desert Storm including shortcoming in the Department of Defense’s ability to provide adequate, timely medical support during contingencies and problems with the planning and execution of these efforts. The Joint Staff also identified problems with the design of the wartime medical system. As a result, the Department of Defense and the military medical corps (Army, Navy, and Air Force) embarked on a series of initiatives intended to correct shortfalls in wartime medical capabilities and to improve medical readiness. This initiative was rapidly accelerated by the events and circumstances following the terrorist attacks of 9/11 and the subsequent Global War on Terror. The goal was to develop and implement a true trauma system, modeled after the successes of civilian systems, but modified to account for the realities of combat. The result was the development of the Joint Theater Trauma System (JTTS). The stated vision of the JTTS is to ensure that every soldier, marine, sailor, or airman injured on the battlefield has the optimal chance for survival and maximal potential for functional recovery. The purview of the JTTS includes injury prevention, prehospital care, acute hospital care, education, leadership and communication, quality improvement/performance improvement, research, and associated information systems. Some of the preeminent functions of the JTTS are discussed below.57
The implementation of the military trauma system (JTTS) has been accompanied by a marked reduction in the number of soldiers killed from combat wounds. The current care fatality rate from Operation Iraqi Freedom and Operation Enduring Freedom of 8.8% compares with the rate of 16.5% during Vietnam. The two primary modes of prevention influenced by the JTTS include realistic/relevant predeployment training and personnel protective equipment.
As a result of the GAO report(s) of the mid-1990s, the Department of Defense partnered with a number of premier Level I civilian trauma centers throughout the United States. This initiative was undertaken to ensure that the military medic would be able to train in a consistent trauma system setting with access to high-volume, high-intensity trauma care. There are currently five major military/civilian collaborative training centers that have evolved to train providers to treat combat injuries and prepare them for the realities of care on the battlefield. These centers include the Navy Trauma Training Center (NTTC) at the University of Southern California (LAC-USC), the Army Trauma Training Center at Ryder Trauma Center (Jackson Memorial Hospital in Miami), and the three Air Force Centers for Sustainment of Trauma and Readiness Skills (C-STARS) located at Baltimore’s Shock Trauma Institute, the University Hospital in Cincinnati, and St. Louis University Hospital.
Data gathered regarding wartime injury patterns have driven force protection changes in combatant training and equipment. The impact of personal protective equipment (body armor) fielded during this conflict has been substantial. As the conflict transitioned from a maneuver war to an insurgency characterized by ambushes and IEDs, wounding patterns changed from small arms injuries to multiple fragment injuries. Rapid fielding initiatives led to changes in vehicular armoring as well as vehicle interior design. The MRAP evolution is an example of a data-driven (injury pattern/severity/number) analysis combined with a prevention initiative forwarded by the JTTS and executed through the line of the military.
Battlefield Care—Clinical Practice Guidelines
The JTTS is responsible for providing clinical oversight of the standard of care across all levels and all services of care both within the theater of care and worldwide. The intent of the JTTS CPG process is to provide continually updated, evidence-based, best practice guidelines for a wide variety of medical circumstances encountered in the battlefield setting. The CPGs are the backbone of the JTTS performance improvement systemwide program. These guidelines are developed and implemented by clinical subject matter experts in response to needs identified in the theater. Currently there are over 30 published CPGs ranging from the management of amputation to vascular injuries. The CPGs are subjected to regular review and are (as possible) based on current evidence-based literature.
Coordination of Care/Leadership
The necessity of establishing a position of trauma system director for the theater of operation (Area of Responsibility [AOR]) was identified early during this conflict. With the support of the Central Command (CENTCOM) Surgeon and the three Surgeons General, the position of trauma system director (JTTS Forward) was rapidly incorporated as a general staff position within the theater medical command. This leadership position (JTTS-F) is responsible for oversight and coordination of the military trauma system within the theater. Responsibilities of the JTTS-F include coordination of patient care/flow across all echelons of care, the implementation of CPGs, capture and analysis of trauma registry data, performance improvement initiatives, and liaison with the medical services of coalition partners. The intrinsic leadership qualities incorporated into the JTTS-F are intended to drive advances within the theater by the process of assured oversight of medical processes combined with advocacy and education.
At the individual combat hospital facility, the development of the JTTS has led to a parallel maturation of trauma leadership positions at a local level. The current theater policy advocates the appointment of a senior trauma clinician at all Level III facilities within the theater. In addition, one trauma coordinator is required for oversight at each CSH to help ensure compliance with guidelines, improve information management, and enable trauma registry data collection.
Before the current conflict, much of the data on combat injury were derived from the Vietnam conflict and the Wound Data and Munitions Effectiveness Trauma database. The data obtained were often fragmentary, always retrospective, and consisted primarily of small series or case reports. Prior to this conflict, there was recognition (from the US civilian trauma system example) that outcome analysis must be data driven and based on an accurately robust and prospectively collected data registry. The development of the JTTR was proposed as a solution to this need. The JTTR was originally fielded prior to this conflict and is in a process of continued maturation and evaluation. It is a registry tool collected on every injured combatant to capture demographics, mechanistic, physiologic, diagnostic, therapeutic, and outcome data. As of January 2010, the JTTR has collected data on over 14,000 casualties. The JTTR is administered by the JTTS. Currently there are over 75 personnel stationed within the CONUS and 10 deployed personnel responsible for the collection, collation, and reporting of the JTTR data. A typical summary of the JTTS-reported data from the conflict is depicted in Fig. 52-30.
FIGURE 52-30 Representative cumulative data from the Joint Theater Trauma Registry.
The commitment of the Department of Defense, the military medical services, and the JTTS to the continued development of the JTTR has resulted in a powerful analysis tool of the current state of military combat medical care. In a yet to be published report, Jenkins and colleagues collected data from combat casualties arriving to LRMC and compared them with the NTDB from the same time frame. This study resulted in the analysis of 1,600 military casualties from this time period. The data demonstrated that the military population was on average younger, more severely injured (ISS score), and more likely to be injured by a penetrating injury or explosive device. The observed care fatality rate for severely injured patients (ISS > 24) was 29/100 in the NTDB and 8.6/100 for the JTTR. Analysis of the Z score revealed a statistically significant number of unexpected survivors in the military population compared with the NTDB. The calculated Z score (actual vs. predicted survivor) was +5.07 with a resultant W score (unexpected additional survivors/100 casualties) of +2.75. This paper and its data serve as a telling and important tribute not only to the JTTR and JTTS but also to the selfless dedication of those deployed in support of the military medical system.
The privilege of serving those who serve our nation is indeed very special. The authors of this chapter wish to acknowledge the men and women of the US military and the dedicated corps of medics deployed throughout the world.
1. DeBakey ME. History, the torch that illuminates: lessons from military medicine. Mil Med. 1996;161:711.
2. Holcomb JB, Stansbury LG, Champion HR, et al. Understanding combat casualty care statistics. J Trauma. 2006;60(2):397.
3. Winkenwerder WJ. Coordination of Policy to Establish a Joint Theater Trauma Registry. Memorandum, Department of Defense Health Affairs; December 22, 2004.
4. Butler F. Tactical combat casualty care: combining good medicine with good tactics. J Trauma. 2003;54(5):S2.
5. Knudson MM, Mitchell FL, Johannigman JA. First trauma verification review committee site visit outside the U.S.: Landstuhl Regional Medical Center, Germany. Bull Am Coll Surg. 2007;92:16.
6. Kowalenko T, Stern S, Dronen S, et al. Improved outcome with hypotensive resuscitation of uncontrolled hemorrhagic shock in a swine model. J Trauma. 1992;33:349.
7. Stern SA, Dronen SC, Birrer P, et al. The effect of blood pressure on hemorrhage volume and survival in near-fatal hemorrhage model incorporating a vascular injury. Ann Emerg Med. 1993;22:155.
8. Burris D, Rhee P, Kaufmann C, et al. Controlled resuscitation for uncontrolled hemorrhagic shock. J Trauma. 1998;46:216.
9. Kaweski SM, Sise MJ, Virgilio RW. The effect of prehospital fluids on survival in trauma patients. J Trauma. 1990;30:1215.
10. Carrico CJ, Canizaro PC, Shires GT. Fluid resuscitation following injury: rationale for the use of balanced salt solutions. Crit Care Med. 1976; 4(2):46.
11. American College of Surgeons Committee on Trauma. Advanced Trauma Life Support. 7th ed. Chicago: American College of Surgeons; 2006.
12. Rhee P, Wang D, Ruff P, et al. Human neutrophil activation and increased adhesion by various resuscitation fluids. Crit Care Med. 2000;28:74.
13. Jaskille A, Alam HB, Rhee P, et al. D-Lactate increases pulmonary apoptosis by restricting phosphorylation of Bad and eNOS in a rat model of hemorrhagic shock. J Trauma. 2004;57:262.
14. Wade CE, Grady JJ, Kramer GC, et al. Individual patient cohort analysis of the efficacy of hypertonic saline/dextran in patients with traumatic brain injury and hypotension. J Trauma. 1997;42:61S.
15. Holcomb JB, McMullen NR, Pierce L, et al. Causes of death in US Special Operation Forces in the global war on terrorism: 2001–2004. Ann Surg. 2007;245:986.
16. Kragh JF, Walters TJ, Baer GC, et al. Practical use of emergency tourniquets to stop bleeding in major limb trauma. J Trauma. 2008; 64:S38.
17. Kragh JF Jr, Littrel ML, Jones JA, et al. Battle casualty survival with emergency tourniquet use to stop limb bleeding. J Emerg Med. 2011;41(6): 590–597.
18. Committee on Tactical Combat Casualty Care. Pre-Hospital Trauma Life Support—Military Edition. St. Louis: Mosby-Elsevier; 2007.
19. Brohi K, Singh J, Heron M, et al. Acute traumatic coagulopathy. J Trauma. 2003;54:1127.
20. Hess JR, Lawson JH. The coagulopathy of trauma versus disseminated intravascular coagulation. J Trauma. 2006;60(6):S12.
21. Martin M, Murray J, Berne T, et al. Diagnosis of acid–base derangements and mortality prediction in the trauma intensive care unit: the physiochemical approach. J Trauma. 2005;58(2):238.
22. Holcomb JB, Jenkins D, Rhee P, et al. Damage control resuscitation: directly addressing the early coagulopathy of trauma. J Trauma. 2007;62:307.
23. Martini WZ, Pusateri AE, Uscilowicz JM, et al. Independent contributions of hypothermia and acidosis to coagulopathy in swine. J Trauma. 2005; 58(5):1002.
24. Niles SE, McLaughlin DF, Perkins JG, et al. Increased mortality associated with the early coagulopathy of trauma in combat casualties. J Trauma. 2008;64(6):1459.
25. Greiser B, Jurkovich G, Luterman A. Severe hypothermia: an ominous predictor of mortality in trauma victims. J Trauma. 1986;26(7):675.
26. Hess JR, Brohi K, Dutton RP, et al. The coagulopathy of trauma: a review of mechanisms. J Trauma. 2008;65:748.
27. Eastridge BJ, Salinas J, McManus JG, et al. Hypotension begins at 110 mm Hg: redefining ‘hypotension’ with data. J Trauma. 2007;63:291.
28. Bruns B, Lindsey M, Rowe K, et al. Hemoglobin drops within minutes of injuries and predicts need for an intervention to stop hemorrhage. J Trauma. 2007;63:312.
29. McLaughlin DF, Niles SE, Salinas J, et al. A predictive model for massive transfusion in combat casualty patients. J Trauma. 2008;64:S57.
30. Bickell WH, Wall MJ Jr, Pepe PE, et al. Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries. N Engl J Med. 1994;33:1105.
31. Roberts K, Revell M, Youssef H, et al. Hypotensive resuscitation in patients with ruptured abdominal aortic aneurysm. Eur J Vasc Endovasc Surg. 2006;31:339.
32. Lu YQ, Cai XJ, Gu LH, et al. Experimental study of controlled fluid resuscitation in the treatment of severe and uncontrolled hemorrhagic shock. J Trauma. 2007;63:798.
33. Borgman MA, Spinella PC, Perkins JG, et al. The ratio of blood products transfused affects mortality in patients receiving massive transfusions at a combat support hospital. J Trauma. 2007;63:805.
34. Spinella PC, Holcomb JB. Resuscitation and transfusion principles for traumatic hemorrhagic shock. Blood Rev. 2009;23:231.
35. Beekley AC. Damage control resuscitation: a sensible approach to the exsanguinating surgical patient. Crit Care Med. 2008;36:S267.
36. Blackbourne LH. Combat damage control surgery. Crit Care Med. 2008; 36:S304.
37. Gunter OL Jr, Au BK, Isbell JM, et al. Optimizing outcomes in damage control resuscitation: identifying blood product ratios associated with improved survival. J Trauma. 2008;65:527.
38. Holcomb JB, Wade CE, Michalek JE, et al. Increased plasma and platelet to red blood cell ratios improves outcome in 466 massively transfused civilian trauma patients. Ann Surg. 2008;248(3):447.
39. Perkins JG, Cap AP, Spinella PC, et al. An evaluation of the impact of apheresis platelets used in the setting of massively transfused trauma patient. J Trauma. 2009;66:S77.
40. Cotton BA, Au BK, Nunez TC, et al. Predefined massive transfusion protocols are associated with a reduction in organ failure and postinjury complications. J Trauma. 2009;66:41.
41. Hess JR, Thomas MJ. Blood use in war and disaster: lessons from the past century. Transfusion. 2003;43:1622.
42. Starr D. Blood: An Epic History of Medicine and Commerce. New York: Harper-Collins; 1998.
43. Ho AM, Karmakar MK, Dion PW. Are we giving enough coagulation factors during major trauma resuscitation? Am J Surg. 2005;190:479.
44. McMullin NR, Holcomb JB, Sondeen J. Hemostatic resuscitation. In: Vincent JL, ed. Yearbook of Intensive Care and Emergency Medicine. New York: Springer; 2006:265.
45. Spinella PC, Moore FA, Holcomb JB, et al. Fresh whole blood transfusions in coalition military, foreign national, and enemy combatants during Operation Iraqi Freedom at a US combat support hospital. World J Surg. 2008;32:255.
46. Spinella PC. Warm fresh whole blood transfusion for severe hemorrhage: U.S. military and potential civilian applications. Crit Care Med. 2008; 36:S340.
47. Spinella PC, Perkins JG, Gratwohl KW, et al. Fresh whole blood is independently associated with improved survival for patients with combat-related traumatic injuries. J Trauma. 2009;66:S69.
48. Makley AT, Goodman MD, Friend L, et al. Resuscitation with fresh whole blood ameliorates the inflammatory response after hemorrhagic shock. J Trauma. 2010;68:305.
49. Spoerke N, Zink K, Cho SD, et al. Lyophilized plasma for resuscitation in a swine model of severe injury. Arch Surg. 2009;144:829.
50. Alam HB, Bice LM, Butt MU, et al. Testing of blood products in a polytrauma model: results of a multi-institutional randomized preclinical trial. J Trauma. 2009;67:856.
51. Koch CG, Li L, Sessler DI, et al. Duration of red-cell storage and complications after cardiac surgery. N Engl J Med. 2008;358(12):1229.
52. Johannigman JA. Maintaining the continuum of en route care. Crit Care Med. 2008;36:377.
53. Rotondo MF, Schwab CW, McGonigal MD, et al. Damage control: an approach for improved survival in exsanguinating penetrating abdominal injury. J Trauma. 1993;35:375.
54. Rasmussen TE, Clouse WD, Jenkins DH, et al. The use of temporary vascular shunts as a damage control adjunct in the management of wartime vascular injury. J Trauma. 2006;61:8.
55. Clouse WD, Rasmussen TE, Peck MA, et al. In-theater management of vascular injury: 2 years of the Balad Vascular Registry. J Am Coll Surg. 2007;204:625.
56. American College of Surgeons Committee on Trauma. Resources for Optimal Care of the Injured Patient: 2006. Chicago: American College of Surgeons; 2007.
57. Eastrdige BJ, Jenkins D, Flaherty S, et al. Trauma system development in a theater of war: experiences from Operation Iraqi Freedom and Operation Enduring Freedom. J Trauma. 2006;61:1366.