2. Epidemiology of Prehospital and Hospital Traumatic Deaths from Life-Threatening Hemorrhage

Stacy Shackelford¹ and Brian J. Eastridge²

(1)

Combat Support Agency, Defense Health Agency, San Antonio, TX, USA

(2)

Department of Surgery, UTHealth Science Center San Antonio, San Antonio, TX, USA

Brian J. Eastridge

Email: eastridge@uthscsa.edu

Keywords

Epidemiology of traumaTrauma deathDamage control resuscitationTrimodal distribution of deathTrauma systemPrehospital deathPrehospital hemorrhage controlPreventable deathTrauma preventionGolden hour

Death from injury was described as the neglected epidemic of modern medicine by the Institutes of Medicine in 1966 [1]. Despite dramatic advances in acute trauma care over the last several decades, including resuscitation of massive hemorrhage, damage control surgery, and technological advances in critical care, the health burden of injury on our society, in both peacetime and wartime, remains substantial. From a public health perspective , injury remains the leading cause of death accounting for 59% of all deaths among individuals up to the age of 45 and is responsible for a domestic cost of more than $406 billion in medical care and lost productivity each year [2]. Medical treatment and loss of work productivity costs for civilian fatal and non-fatal injuries in the United States totaled more than $671 billion [3]. Since injury is disproportionately represented in a relatively young population, it stands as the single largest cause of years of life lost and productivity lost in the United States. In 2015, 214,000 persons in the United States suffered fatal injury; more than 2,800,000 persons were hospitalized and 27,600,000 persons were treated in emergency departments for non-fatal injuries. The majority of injury mortality occurs in the field with or without access to medical care [4–6]. According to a Centers for Disease Control and Prevention report in 2008, 62% of all people who died from injuries and 75% of people who died from gunshot wounds were pronounced dead outside of a hospital [7].

Understanding the epidemiology of death after trauma is vital to improving the outcomes of the injured patient. The concept of the distribution of mortality after injury along a chronological axis was initially characterized by Trunkey based upon his experience and research in his seminal work describing the trimodal distribution of trauma death. This distribution of death after traumatic injury is classically described with death occurring during immediate, early, and late timeframes after injury [8] (Fig. 2.1).

../images/453814_1_En_2_Chapter/453814_1_En_2_Fig1_HTML.png — Fig. 2.1

The trimodal distribution of trauma deaths. (From Trunkey [8] with permission of Springer Nature)

In an associated review of 425 consecutive trauma autopsies, he found the most substantial etiology of mortality across the spectrum of injury was hemorrhage, which was responsible for 35.2% of deaths [9]. From this early work evolved concepts of injury prevention , expedited evacuation, and optimized acute healthcare delivery which formed the nascent architecture of regionalized trauma care and were the precursor to our current trauma systems across the United States. As initially described by Dr. Trunkey, “immediate” deaths occur within 1 hour of injury and were considered unpreventable through available medical interventions. Immediate deaths are most frequently caused by catastrophic whole body, central nervous system (CNS) , heart, or great vessel injury. From a trauma system perspective, such immediate deaths are best addressed through an inclusive trauma system integrating injury prevention and safety interventions. “Early” deaths after trauma, usually occur within the time realm of prehospital or acute medical care occurring later than immediate but still within the first few hours after injury. Most early deaths are attributable to major CNS injuries or hemorrhage [10, 11]. As little can be done to ameliorate the effects of primary CNS injury, clinical efforts are directed toward optimization of brain perfusion and minimizing secondary brain injury. Assuming these tenets, the mortality of injured patients who succumb to CNS injury is largely not preventable. On the other hand, some of the deaths secondary to hemorrhage during this interval are potentially preventable and highlight opportunities to advance medical interventions and trauma systems. The interval between injury and definitive control of the focus of bleeding is most critical for this group of injured patients. The third “peak” in trauma deaths corresponds to trauma patients who die days or weeks after injury, usually due to infection, multiple organ failure, or the latent effects of devastating brain injury. Optimal care in the early hours after injury may prevent the progression of such sequelae. Improvements in critical care have improved injury outcomes and minimized the mortality from these clinical entities as evidenced by recent publications have documented a diminution in the significance of this late third peak [12, 13]. It is especially notable that death after trauma is largely an acute phenomenon with approximately 40–64% of deaths occurring at the scene [4, 9, 11]. For those patients that make it to a trauma center and ultimately die, 34–52% succumb to their injuries within the first 24 hours, and the remainder distributed over the subsequent days to weeks [12, 14, 15].

Reducing the time between injury and life-saving interventions is a critical factor in optimizing injury survival. While the exact length of time that an individual patient can survive depends on their specific injuries, 1 hour has been frequently cited as a goal to deliver an injured patient to a facility capable of surgical management of bleeding in both the civilian sector and on the battlefield [16–18]. Although objective data to support the targeted 1 hour prehospital time have been elusive, few question the fact that earlier interventions save lives. On heels of Korean War, the US Army awarded Dr. R Adams Cowley, a cardiothoracic surgeon, a grant for $100,000 to study shock in humans. Most patients presented to his facility physiologically moribund, earning his four-bed unit the moniker of the “death lab.” Owing to lessons learned from the Vietnam War, in 1968, he negotiated to have patients brought in to his facility by military helicopter to minimize prehospital time after injury. Based upon subsequent clinical experience with injury, in 1975, he published his perspective on the development of a comprehensive emergency medical system in the Maryland State Medical Journal. His quote that “the first hour after injury will largely determine a critically injured person’s chances for survival” developed into the concept of the “golden hour” which has remained as one of the core guiding tenets of trauma care for emergency medical services for over the last four decades. Dr. Cowley coined the legendary term to promote the urgency between injury and care, recognizing that trauma patients who reached definitive care sooner had a better chance of survival [19]. He subsequently established Baltimore Shock Trauma Center and a statewide system of care served by Maryland state police helicopters piloted by Vietnam veterans.

Advances in both military and civilian trauma systems have focused attention on those deaths determined to be potentially preventable through medical means. Although numerous methods of defining “preventable death” have been established, there is no standard definition that has proved universally acceptable, highlighting the challenges of developing such metrics. Regardless of the definition of preventable , hemorrhage consistently emerges as the most substantive pathophysiology associated with potentially preventable trauma mortality. In a large contemporary autopsy study of combat deaths from 2001 to 2011, 87% of the 4574 deaths occurred prior to arrival at a medical treatment facility (MTF) , and of the prehospital deaths, 24% were considered potentially survivable based on a process of expert review of anatomic criteria established in the study [20] (Fig. 2.2a, b).

../images/453814_1_En_2_Chapter/453814_1_En_2_Fig2_HTML.jpg — Fig. 2.2

(a) Battlefield mortality location (n = 4596). (b) Injury/physiologic focus potentially survivable acute mortality (n = 976). (From The Journal of Trauma and Acute Care Surgery, Eastridge et al. [20] Figure 4, with permission of Wolters Kluwer Health, Inc.)

Of the pre-hospital casualties with potentially survivable injuries, 91% of the deaths were associated with a source of hemorrhage . Further stratification noted the site of lethal bleeding as follows: torso 67%, junctional 19%, and extremity 14%. The focus of bleeding in the torso hemorrhage death casualties was predominantly thoracic in 36% and abdominopelvic in 64%. Similar classification of the junctional hemorrhage deaths demonstrated 61% were associated with axilla and groin injuries, whereas 39% were associated with cervical injuries [20]. Another study utilizing the same methodology analyzed 558 combat casualties who succumbed to their injuries after reaching a military treatment facility. These died of wounds (DOW) casualties occurred at a rate of 4.6% over the study period, which is strikingly similar to the average civilian trauma center case fatality rate of 4.1%. Of the 287 (51.4%) DOW casualties deemed potentially survivable, 80% of the mortality was directly associated with a source of acute hemorrhage early in the hospital course [21].

By comparison, analyses of civilian trauma deaths, where blunt mechanism of injury is more prevalent, clinical studies also demonstrate that hemorrhage is the most substantial contributor to early trauma deaths. A 1998 analysis of trauma center mortality demonstrated that nearly all of the traumatic mortality directly attributable to hemorrhage occurred within 24 hours from injury [22]. A comparable review of in-hospital deaths classified as preventable or potentially preventable demonstrated that 40% were caused by hemorrhage [15]. Similarly, another metropolitan trauma center performed a review of 753 consecutive trauma deaths in their hospital. Of these deaths, 53% occurred within 12 hours and 74% within 48 hours. Of this population, 37% of the mortality was attributable to acute hemorrhage [14]. A study of civilian prehospital deaths in a large urban county designated 29% of the mortality as potentially preventable, with 64% of those deaths deemed potentially survivable attributed entirely or partially to hemorrhage [23].

The prevalence of prehospital deaths in recent conflicts in the southwest Asia remained essentially unchanged compared to previous US wars. The lack of effective management strategies to mitigate life-threatening hemorrhage secondary to trauma has long been recognized as a knowledge and capability gap requiring remediation. In a classic military manuscript, Dr. Bellamy reviewed the nature of ground combat deaths in a hypothetical model which incorporated data from World War II, the Korean War, and the Vietnam War into a prediction of the causes of death in combat [24]. Approximately 44% of deaths were associated with limb hemorrhage, thereby highlighting extremity bleeding as one of the most substantive causes of potentially preventable death on the battlefield (Fig. 2.3).