A Decade of Advances in Military Trauma Care

Abstract

Background:

While combat casualty care shares many key concepts with civilian trauma systems, its unique features mandate certain practices that are distinct from the civilian ones.

Methods:

This is a review of the most current literature on combat casualty care, based on computer database searches for studies on combat casualty care and military medicine. Studies were selected for inclusion in this review based on their relevance and contribution.

Results:

Over the last decade, meticulous, international data collection and research efforts have led to significant improvements in military trauma care. Combat medicine has focused on the causes of preventable deaths and targeted on bleeding control and resuscitation strategies, as well as improved evacuation. En route care and forward surgical interventions have resulted in unprecedented low fatality rates and the saving of more lives.

Conclusion:

This overview of the developments in combat casualty care in recent years emphasizes medical practices that are characteristic of combat medicine, yet with the potential to save lives in other scenarios, as well.

Introduction

Trauma casualties present a unique challenge, even for experienced healthcare providers working under optimal conditions. Care and management of these casualties require experience and expertise. Timely treatment is one of the most important variables affecting outcome. Combat scenarios further complicate matters; the austere environment and scarcity of resources often hinder the provision of optimal care. Geographical distances and other tactical limitations often prolong evacuation times. These attributes of the battlefield, along with the particular characteristics of combat injuries, significantly differentiate military trauma care from its civilian counterpart.

Medical care provided on the battlefield has long been recognized as a platform for learning and for applying lessons learned, both in military and civilian medical systems. An important development in military trauma care in recent years is the emphasis on academic standards in a field that has long straggled for the implementation of evidence-based medicine. The value of learning from past experience is well recognized. However, the establishment of clear definitions (1) and measurable outcomes (2), along with continuous, focused research, is at the crux of the explosion of data and improved outcomes observed in recent years.

The last decade has seen major conflicts waged by multinational coalition forces, particularly in Iraq (Operation Iraqi Freedom—OIF) and in Afghanistan (Operation Enduring Freedom—OEF). Unlike in previous large-scale conflicts, the medical care provided in these conflicts was accompanied by meticulous data collection and documentation. These data were then used to characterize injury patterns, the medical care provided, casualty outcomes, and mortality causes. The information was in turn used to promote and evaluate changes in the medical care provided to trauma casualties.

A potentially salvageable death describes a casualty for which the sustained injury that led to the death would be survivable under optimal medical care. Analysis of all combat-related mortality sustained during OEF or OIF in the last decade reveals that up to 25% of all deaths were potentially salvageable (2). Further exploration reveals that the vast majority (90%) of these deaths is attributed to exsanguination, while a smaller proportion is related to airway compromise (8%) and tension pneumothorax (1%) (2). These data have both clinical and research implications. The focus during OEF and OIF on improving care for injuries that are classified as causes of preventable death led to a reduction in case of fatality rate (the ratio between mortality and the total number of injured patients) to under 10%, the lowest figure in the history of military medicine (3). This dramatic improvement in the care provided to injured personnel on the battlefield is reflected in lower mortality rates in military casualties suffering vascular injuries compared to a matched civilian standard (4). Such merit of military medical care can be attributed to prehospital tactical combat casualty care (CCC), rapid medical evacuation to surgical facilities, strict implementation of clinical practice guidelines, and a trauma system constantly investigating and executing necessary changes. Looking into the future, we face the challenge of staying updated, as we strive to implement lessons learned and to further improve trauma and CCC.

This article will discuss some of the most significant improvements achieved in CCC in recent years, with an emphasis on medical practices that are characteristic of military medicine. Hemorrhage will be a particular focus, since it accounts for the majority of preventable trauma-related mortality and since the main improvement in CCC in recent years has been the reduction of hemorrhage-related mortality. A complete review of all advancements made in recent years cannot be performed in the scope of this article. We chose to focus on the advancements relevant to most battlefields, while regretfully omitting many important achievements such as advancements in personal protective gear, armed vehicles, data collection and trauma registries, and more.

Tourniquets

Probably the most significant advancement in prehospital trauma care in recent years is the widespread implementation of tourniquet use. As recently as the Vietnam War, tourniquets were considered a last resort, and their use was instructed only following failure of all other measures for hemorrhage control. This approach resulted in 7.8% mortality attributed to extremity wounds (5). At the start of the Afghanistan conflict in 2001, many units were not equipped with tourniquets and the recommendation was not to apply tourniquets unless all else failed, an approach similar to that adopted in the Vietnam War. This conservative approach toward tourniquet application can be attributed to a possible potential for associated morbidity, such as limb shortening in 0.4% and localized limb palsy in 1.5% most often incomplete and temporary (6). In 2004, following a large number of deaths from extremity hemorrhage, and congruent with growing clinical and laboratory data, experts on military medicine issued a recommendation for the widespread distribution of tourniquets. By 2007, the majority of the US military was equipped and trained in tourniquet use (7). The use of tourniquets on the battlefield was found to be associated with increased survival (8); the death rate from extremity hemorrhage declined by 85% after full implementation of protocols for tourniquet use (2). Another example is evident in the Israeli Defense Force (IDF), where tourniquets have been widely distributed and used for the past 20 years by both medical personnel and combatants. Until recent years, the tourniquets used by the IDF were an elastic silicone band for upper extremity hemorrhage or an improvised “Russian” tourniquet, comprising a cotton band twisted by a rigid stick to apply pressure for lower extremity hemorrhage (9). As part of the IDF-Medical Corps (IDF-MC) force buildup plan, the Combat Application Tourniquet (CAT), a standardized tourniquet with well-established efficacy (8), was distributed to all IDF combatants and medical personnel.

While many alternative tourniquets exist, the specific product used is not critical. Most important is the recognition that early control of compressible extremity hemorrhage is one of the most significant aspects of improving prehospital care. The wide distribution of an easy-to-use rapidly applicable device, and its application as close as possible to the point of injury, will promote considerably the care provided to bleeding casualties.

Hemostatic Dressings

For the last two millennia, and up until recent years, gauze has been the only available dressing bandage. Hemostatic dressings are new agents used to control compressible hemorrhage. A number of active ingredients are available, which generate the desired effect of topical clot formation. The first generation of hemostatic agents included the use of fibrin-containing bandages. A number of US Food and Drug Administration (FDA) -approved available agents have been developed since. One of them is chitosan, a polysaccharide produced from crustacean shells, which cross-links red blood cells to form a clot. Another available agent, nonwoven kaolin, aluminosilicate clay, activates the intrinsic coagulation pathway. Other products have also been developed. While these agents have demonstrated superior efficacy in compressible hemorrhage control compared to regular gauze (10), no one alternative has shown clear superiority over others (11). Presently, the most frequently used hemostatic dressing is the Combat Gauze®, which combines surgical gauze with the aluminosilicate kaolin. Despite several reports of positive experience with Combat Gauze, efforts continue toward development of a more effective hemostatic agent.

Tranexamic Acid

The antifibrinolytic tranexamic acid (TXA) is a well-known agent used for hemorrhage control at various sites. Recent studies have demonstrated a positive effect of TXA on the survival of bleeding patients. The 2010 Clinical Randomization of an Antifibrinolytic in Significant Hemorrhage 2 (CRASH-2) trial, a prospective study of approximately 20,000 trauma patients, demonstrated a significant reduction in mortality rate among casualties who received TXA compared to a control group who did not receive the drug. Early administration of the drug (<1 h from injury) was associated with the most significant reduction on mortality risk (12). The CRASH-2 trial was the subject to some degree of criticism, mainly due the possible effect of undeveloped trauma systems, selection criteria, and different attributes of the trauma centers involved (13). Nevertheless, evidence indicating the beneficial effect of TXA on hemorrhaging casualties quickly led to its use in military scenarios (14, 15). Data retrieved from military settings demonstrated a positive effect of early administration of TXA, similar to that observed in civilian scenarios, and particularly pronounced in patients requiring massive hemorrhage (15). The use of TXA at the level of the surgical units has become common practice in the majority of modern militaries. Congruent with data suggesting augmented efficacy of TXA with early administration (12), several military medical systems have attempted to administer this drug as early as possible. Indeed, in the IDF, TXA is an integral part of the point of injury treatment provided to casualties with suspected hemorrhage (14). The British airborne medical evacuation unit—the Medical Emergency Response Team (MERT)—administers TXA as part of the en-route care provided to bleeding casualties.

Blood Products

Balanced component therapy is currently considered the gold standard for the treatment of hemorrhaging trauma patients, as part of damage control resuscitation (DCR) principles. This approach supports transfusion of blood products in a 1:1:1 ratio between red blood cells, plasma, and platelets (16, 17). The implementation of this approach in advance military units and combat support hospitals is one of the most significant advancements of military medicine during recent years; similar approaches have subsequently been adopted in civilian medical systems (18). Data collected in the last decade from deployed combat support hospitals have indeed demonstrated an increased ratio of transfusion plasma and platelets to red blood cells, thus mimicking the composition of whole blood as closely as possible (19).

The implementation of balanced component therapy in the prehospital setting is challenged by significant logistic constraints. Red blood cells require refrigeration and are thus only available in advanced medical units. Fresh frozen plasma, which is the most commonly used preparation of plasma, requires deep-freezing and a long thawing process. Platelets have a short shelf life and require constant agitation, and are thus irrelevant to combat scenarios. Military medical units that can provide medical care at the point of injury must be highly mobile. These units rarely have refrigeration capabilities and are thus unable to use red blood cells, platelets, or fresh frozen plasma. As the vast majority of preventable deaths are attributed to hemorrhage, attempts are made to implement DCR principles as close as possible to the point of injury, despite the logistic difficulties.

Attempts to bring blood products forward include the use of freeze-dried or cryopreserved blood products, such as those currently used by The Netherlands military. This involves specific deep-freezing techniques that cause minimal derangements to the frozen blood products. Storage time of deep-freeze blood products is considerably longer than that of products stored at 4°C or at room temperature (20). Unfortunately, the use of cryopreserved blood products is limited to medical units with refrigeration and defrosting capabilities. Efforts to freeze dry red blood cells and platelets continue. The use of freeze-dried (lyophilized) plasma (FDP) will be discussed below.

Fresh Whole Blood

Fresh warm whole blood donated by uninjured soldiers and immediately transfused to a bleeding casualty entails several advantages. The restoration of all missing blood components is a main benefit of “buddy transfusion.” Furthermore, a fresh warm blood product is probably more effective in correcting the various derangements caused by hemorrhage. Some evidence suggests that one unit of fresh whole blood may induce a hemostatic effect similar to that of 10 platelet units (21), while other evidence suggests a similar effect on survival compared to that afforded by component therapy (22). Nevertheless, the use of fresh whole blood is subject to a number of key considerations. The use of nontyped whole blood requires the transfusion of type O blood that has undergone antibody screening to ensure a low titer of anti-A and anti-B antibodies (23). Such testing is not feasible in out-of-hospital settings. Furthermore, the use of typed whole blood requires typing both the donor and the recipient; this can be done either before battlefield deployment or on-spot sampling in the austere environment of the battlefield. Both techniques entail merits and significant disadvantages and both are associated with a non-negligible chance of error (24, 25). The transmission of infectious diseases in unscreened blood is another important concern, and while mandatory screening and vaccination for all servicemen might reduce this risk (25), it remains an important consideration.

Despite the recognized limitations, fresh whole blood has been transfused in every major US military conflict since World War I (24), including recent conflicts in Iraq and Afghanistan (25). The current US military doctrine allows for fresh whole blood use in emergency life-threatening scenarios in combat zones, when tested stored blood components are unavailable, or when a patient does not respond to stored blood component resuscitation (26). The Norwegian navy adopted the use of fresh whole blood through a designated training program for “buddy transfusion,” named the Blood Far Forward training program (27), while some military medical systems worldwide preclude the use of fresh whole blood entirely.

FDP

Plasma can have substantial benefit as a resuscitation fluid in the treatment of the hemorrhaging patient (16, 18, 19). This use of plasma is based on data indicating an association between the initiation of earlier plasma transfusion in the hospital setting and positive patient outcomes (18, 28), as well as evidence of deleterious effects of crystalloids of colloids as primary resuscitation fluids (29). The beneficial effect of plasma resuscitation is likely due to the avoidance of dilutional coagulopathy, the replacement of both pro- and anticoagulant proteins, the repair of endothelial function, and the promotion of anti-inflammatory effects (30). Furthermore, plasma resuscitation precludes infusion of acidic crystalloids, which exacerbate the metabolic acidosis that is part of the “lethal triad” of trauma. While, as mentioned above, the use of Fresh Frozen Plasma is not feasible at the point of injury, FDP is temperature stable, lightweight, and rapidly reconstituted, making it logistically compatible as a primary resuscitation fluid at the point of injury (31). The use of FDP as a resuscitation fluid is hardly innovative; dried plasma was already used in World War II by the US Armed Forces. However, early dried plasma was then pooled from as many as 1000 donors, introducing a substantial risk for blood-borne infections (32). This changed in the 1990s, when the French Blood Bank began producing dried plasma pooled from approximately 10 donors. Medical units of the French Army, as well as of the German Armed Forces, have used FDP in conjunction with the development of new, safer products. However, its use was limited to advanced medical units, and point of injury use was not attempted. Recently, the IDF-MC introduced the use of the German LyoPlas®, making it the resuscitation fluid of choice for transfusion by advanced life support providers for patients suffering from substantial hemorrhage (30). LyoPlas® is a single donor FDP product (33). The use of type AB male donors ensures universal ABO and Rh compatibility. To date, several dozen units of LyoPlas have been transfused at the point of injury to bleeding casualties, with no adverse reactions or technical difficulties reported (30).

Medical Evacuation

Rapid evacuation to a medical treatment facility with advanced medical capabilities, including damage control surgery (DCS), remains the mainstay of treatment according to the vast majority of clinical practice guidelines employed by military medical systems. The Vietnam War was the first conflict to demonstrate extensive aeromedical evacuation using platforms staffed with dedicated medical personnel on board; over 900,000 casualties were evacuated. These teams were capable of providing en-route care, including basic hemorrhage control, fluid resuscitation surgical airway establishment, and pain control. Modern warfare introduced several distinct evacuation platforms. The US military employs both DUSTOFF evacuation helicopters staffed with a medic capable of providing basic life support and the PEDRO air evacuation teams, which include on-board fighting paramedics. Continued efforts are made to upgrade the level of training of these teams, promoting improved medical and operational capabilities (34). The British Royal Air Force operates the MERT, a platform manned by two paramedics, one physician and a nurse, capable of providing advanced life-saving interventions, including transfusion of blood products. Morrison et al. examined the benefit afforded by on-board advanced medical capabilities. In a study that comprised 865 casualties classified to three injury severity scoring (ISS) categories (1–9, 10–25, and 26+), improvement in the hemodynamic status of casualties throughout medical evacuation was demonstrated in platforms that were capable of providing advanced medical care but not in those providing basic life support only (35). Other studies demonstrated a survival benefit to platforms that provide advanced medical care, particularly for casualties with an intermediate ISS score (36). The IDF aerial evacuation units consist of a medical team that includes an intensive care physician (either a surgeon, an emergency medicine specialist, or an anesthesiologist), a second physician in training or a paramedic, and two combat medics. These teams can operate on various aerial platforms and are capable of providing advanced medical care, including life-saving interventions, advanced ventilation, and transfusion of plasma and packed red blood cells (pRBCs). The aerial evacuation force is utilized in low-threat scenarios, including evacuation of civilians injured at locations distant from medical treatment facilities, and also in high-threat scenarios, in austere and hostile environments mandating combat adequacy.

The US critical care air transport (CCAT) is designed to transport casualties to definitive-care facilities located out of theater, up to thousands of miles away. The teams consist of a critical care physician, a critical care nurse, and a respiratory therapist, and are designed to augment standard aeromedical transport teams when critical patients are transported. The teams are intended to be independently functioning mobile intensive care units capable of providing in-flight critical care to three ventilated patients (37). Efforts continue to expand their capabilities to provide care to sicker and sicker patients, including, for example, several cases of successful use of in-flight extra-corporal lung support (38).

Operational risks and long evacuation distances make combat aerial evacuation especially challenging. These conditions pose substantial medical and tactical demands, considerably different from the challenges faced by civilian platforms. Despite the differences between the platforms, civilian aeromedical evacuation systems have developed in parallel to the introduction of these capabilities to the battlefield (39). Even today, experience gained in military scenarios continues to have considerable influence on the development and improvement of aerial capabilities in both military and civilian settings.

Evacuation of trauma casualties by air entails several significant advantages over ground evacuation, the main advantage being timely arrival at a medical treatment facility. This is specifically true on the battlefield, where long distances and an austere environment render fast ground-based evacuations practically impossible. In fact, during several conflicts in Israel, the majority of severely wounded soldiers were evacuated by air directly from the point of injury to a civilian medical center. Despite its many benefits, aerial evacuation can be severely compromised on the battlefield, mandating the militaries to continue to develop and maintain also reliable, though slower, ground evacuation capabilities.

Forward Surgical Capabilities

Early surgical capabilities remain key to the medical care provided to trauma victims in both the civilian and military settings. Modern warfare is waged in various scenarios. While medical support for conflicts in close proximity to civilian populations can be attained from civilian medical centers that serve as definitive-care facilities (the “Israeli model”), the provision of medical support for remote campaigns necessitates the establishment of a full medical arsenal and deployment of advanced medical capabilities. The recent conflicts in Iraq and Afghanistan witnessed the most advanced combat support hospitals in the history of combat medical support. These facilities included advanced imaging techniques and experts in neurosurgery, cardiothoracic surgery, vascular surgery, and more (40). The main disadvantage of such robust facilities is that, similar to civilian medical centers, they are stationary. Moreover, they occasionally mandate prolonged evacuations in order to be reached, which may be even further delayed due to operational considerations. The concept of allocating damage control surgical capabilities forward, in order to enable faster access to surgical capabilities, is a relatively new one. In the 1990 Panama conflict, the US military deployed, for the first time, small mobile and highly skilled medical teams capable of providing DCS. The composition of such Forward Surgical Teams (FSTs) varies according to their designated mission, from a team of approximately 20, including at least four surgeons, eight nurses, and two surgical technicians, to four person jump teams that consist of one surgeon, two nurses, and one surgical technician (41). FSTs are designed to provide high quality care (including DCS) to a small number of patients closer to the point of injury and on an earlier echelon of care. The main benefit afforded by FSTs’ highly trained personnel is the provision of expert triage and intensive care (42), with surgical capabilities an important adjunct. In a series describing the experience of such a team, up to 43% of 761 casualties underwent surgical treatment.

Data Gathering

Combat-related data collection has advanced significantly in recent years. Recognition of the importance of ongoing data analysis prompted the establishment of several dedicated military trauma registries, focusing on injury, medical treatment, evacuation, hospitalization, and outcomes of combat injuries. The importance of international collaboration has similarly been recognized, leading to the formation of multinational learning processes, including joint investigation of “after action reports,” shared registries, and more. Similar collaboration has also developed between military and civilian systems, thus enabling more efficient and reliable knowledge creation and utilization, ultimately directed toward a common goal shared by all—saving as many lives as possible.

Conclusion

The field of CCC and military trauma care has undergone a substantial leap in recent years. While some of the medical advancements of CCC will remain irrelevant to civilian medical systems and vice versa, others offer great opportunities for implementation of lessons learned on the battlefield to civilian medical care. Only by reciprocal learning can the full potential of these opportunities be achieved, thus improving the care provided to the wounded, on the battlefield and in the civilian population, and ultimately saving lives around the world.