Military medical revolution (2012)

INTRODUCTION The battlefield has seen tremendous revolutions in military medical affairs (RMMAs) as a result of the last decade of continuous combat operations. The advances in deployed and en route combat casualty care are categorized as individual RMMAs shown in Table 1. As with prehospital advances, the basis for many of the RMMAs in the deployed hospital care environment as well as en route care was translated from civilian trauma practice but is realistic and relevant to the battlefield context. As the conflict evolved, the substantive data from the battlefield led to many new paradigms of treatment and evacuation. The successful implementation of many of these battlefield practices was then effectively translated back into the civilian injury care environment as has been typical of medical advances developed subsequent to previous conflicts of antiquity.TABLE 1: RMMAs, 2001 to 2011 OCOs in Afghanistan and Iraq.The RMMAs that occurred during the last 10 years of combat casualty care are in the realm of deployed hospital care and en route care and are discussed in detail in this article. DEPLOYED HOSPITAL CARE Global Combat Damage-Control Surgery Damage-control surgery is well established in civilian trauma centers and is described as the trilogy of abbreviated operation, intensive care stabilization/resuscitation, and the return to the operating room for the last or multistage procedures for the definitive surgical repair. This paradigm has reduced mortality for the patient population with severe abdominal injuries1 and has gained widespread acceptance. In the civilian trauma systems, this trilogy usually occurs in one hospital. This approach has been described for all anatomic injuries in the severely injured patient at risk for physiologic decompensation.2,3,4 In contrast to the civilian damage control, global combat damage-control surgery often involves multiple separate surgical facilities, multiple surgeons, multiple resuscitation and stabilization episodes, helicopter evacuation, and fixed-wing evacuations by the Critical Care Air Transport Team (CCATT) during a multistage global transit (Fig. 1).4–5Figure 1: Global combat damage-control surgery.Global combat damage control has been successfully conducted for thousands of combat-wounded patients within a matter of several days and represents a profound revolutionary change in the care of patients severely wounded in combat. Damage-Control Resuscitation Damage-control resuscitation (DCR) is one of the most significant RMMAs to develop from the overseas contingency operations (OCOs) in Iraq and Afghanistan. As introduced in a 2007 special commentary by Holcomb et al.,6 DCR is described as “a structured intervention [which] begins immediately after rapid initial assessment in the ED and progresses through the OR into the ICU. All efforts are directed towards this goal of preventing/correcting hypothermia, acidosis, and coagulopathy by repeated point of care testing and the use of multiple blood products and drugs readily available in theater, albeit in new ratios and amounts.” DCR consists of two major efforts as follows: permissive hypotension to prevent excessive bleeding and hemostatic resuscitation, which stresses the administration of blood products in a 1:1:1 manner.5 Most trauma patients are not coagulopathic and do not require blood product resuscitation. However, up to 25% of severely bleeding trauma patients present with acute coagulopathy, and mortality in these patients can be as high as 50%. During the course of the last decade, the US military medical community has developed the concept of DCR to treat this subset of critically injured patients. This revolutionary change improved doctrine developed in the latter half of the 20th century. The cornerstone of the DCR revolution is the aggressive use of blood products including packed red blood cells (PRBCs), fresh frozen plasma (FFP), and platelets in ratios near 1:1:1. Military studies conducted during the Iraq war suggested that patients receiving higher ratios of FFP to PRBCs had lower mortality rates (19% vs. 65%) compared with those who received lower ratios (1:8).6 Similar results have been found in the civilian setting, where a retrospective analysis of patients receiving massive transfusions found a lower mortality (26% vs. 87.5%) in those who received FFP/PRBC in a higher ratio.7 Current military DCR clinical practice guidelines (CPGs) state that, “The goal of transfusion of the patient with need for massive transfusion is to deliver a ratio of PRBCs to plasma to platelets of 1:1:1.”8 As soon as patients arrive to the emergency department and are identified as likely to require massive transfusion, the DCR protocol is initiated; thawed plasma is used as a primary resuscitation fluid in a 1:1 ratio with PRBCs. This process continues through the operating room and into the intensive care unit. Crystalloid use is thereby significantly limited, as are other resuscitative adjuncts such as cryoprecipitate and tranexamic acid (TXA). TXA in Trauma Resuscitation The landmark CRASH-2 trial testing the safety and efficacy of TXA in trauma resuscitation marked a turning point in the treatment of trauma patients. For the first time, a single pharmaceutical intervention was shown to reduce mortality in hemorrhaging trauma patients. This study documented the benefit of TXA in real-world clinical practice across a wide variety of settings, including austere environments. Reinforcing the revolutionary findings of CRASH-2, an analysis of early use of TXA by United Kingdom physicians at the North Atlantic Treaty Organization Role 3 Bastion hospital in Afghanistan documented similar results in combat casualties.9 In this study of 896 casualties, 32.7% (n = 293) received TXA, while 67.2% (n = 603) did not. The patients receiving TXA had a higher survival rate (82.6% vs. 76.1%; p = 0.028) than the massive transfusion subgroup receiving TXA (28.1% vs. 14.4%; p = 0.004). Multivariate regression modeling of the massive transfusion cohort showed that TXA use was independently associated with survival (odds ratio [OR], 7.28; 95% confidence interval [CI], 3.02–17.32). TXA is the first targeted therapy to be proven effective in hemorrhaging trauma patients, and CRASH-2 provides Level I evidence to support its use. TXA has been incorporated into the Joint Trauma System CPG for DCR and has been recommended as an option prehospital by the Committee on Tactical Combat Casualty Care and the Defense Health Board (DHB memo, TXA). Diagnostic Evaluation for Explosion Injury Current practice for evaluating and treating penetrating injury to the abdomen, flank, and pelvis has undergone a drastic and profound change during OCOs. From World War I until 2004, a tenet of military surgery was to explore all patients with abdominal penetrating injury.10–12 The advent of computed tomographic (CT) scan on the battlefield in Role 3 facilities has allowed visualization of the position of metallic fragments in penetrating abdominal injury patients. Beekley et al.13 describe the successful nonoperative treatment of up to 60% of stable patients with penetrating fragments to the abdomen in the absence of frank peritoneal signs on physical examination and no intraperitoneal or retroperitoneal penetration of the fragments. With an available CT scanner, the mandate of surgical exploration for all penetrating abdominal wounds has been abandoned. The CT scanner has thus successfully revolutionized the care of combat wounded with penetrating abdominal injuries by avoiding iatrogenic morbidity associated with negative exploratory laparotomies. Vascular Surgery The revolution in vascular injury management during the wars in Afghanistan and Iraq has at its core the resolute joining of combat-wounded patients with surgeons soon after the time of injury. This paradigm has been sustained because of a combination of life-preserving tactical combat casualty care, strategic positioning of forward surgical capability, and use of rapid medical evacuation (MEDEVAC) within a Joint Trauma System. This model of uniting a salvageable patient with a surgeon at a capable facility minutes after injury represents a profound change in how vascular trauma is managed. Evidence of this new paradigm is found in epidemiologic studies that report the rate of vascular injury on the modern battlefield to be five to six times higher than the rate reported in previous wars.14–16 These studies capture the phenomenon of patients surviving to arrive at surgical facilities to have their injuries recorded and treated. Furthermore, for the first time in modern war, many of these decisions are made by surgeons with subspecialty vascular and cardiovascular training.17 Within this new paradigm, the revolution of military medical affairs as they pertain to vascular disruption, hemorrhage, and/or ischemia on the battlefield encompasses the following: forward deployment of subspecialty trained peripheral vascular surgeons,15,17 definition of a neuromuscular ischemic threshold of the limb (<5 hours),18,19 the need for expedited reperfusion following extremity vascular injury and ischemia,20,21 reconstruction of vascular injury using saphenous vein as the conduit of choice,15,20 repair of proximal watershed extremity vein injuries,15,22 ligation of select minor or distal extremity vascular injuries (arterial and venous),14,23 necessity of viable tissue coverage of vascular reconstruction to prevent disruption,24,25 temporary shunts as an adjunct to accomplish reperfusion or venous outflow rapidly,26–28 endovascular techniques to treat select patterns of vascular injury or disruption,29,30 and endovascular balloon occlusion as a hemorrhage control or resuscitation adjunct.31–33 These advances made during the decade of war in Afghanistan and Iraq have been a result of the modern paradigm in which a salvageable patient is evacuated to a surgeon at a capable facility within minutes after injury. In aggregate, these advances represent a profound change in how vascular injury is managed in modern combat. Orthopedics Like other aspects of casualty care, orthopedic surgery has profoundly changed since the Vietnam War. Since 82% of all soldiers wounded in action not returning to duty have at least one extremity injury, these changes have a significant impact on battle casualties.34 Damage-control orthopedics refers to an approach that is designed to not place the most severely injured patients at further risk by aggressive early total care. The common practice is early, rapid, temporary stabilization of a fracture to minimize blood loss, then physiologic stabilization, and finally definitive orthopedic management.35 The steps in this practice have been shown to be successful for unstable patients. 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