Todd E. Rasmussen

Death on the battlefield (2001-2011): implications for the future of combat casualty care.

BACKGROUND Critical evaluation of all aspects of combat casualty care, including mortality, with a special focus on the incidence and causes of potentially preventable deaths among US combat fatalities, is central to identifying gaps in knowledge, training, equipment, and execution of battlefield trauma care. The impetus to produce this analysis was to develop a comprehensive perspective of battlefield death, concentrating on deaths that occurred in the pre–medical treatment facility (pre-MTF) environment. METHODS The Armed Forces Medical Examiner Service Mortality Surveillance Division was used to identify Operation Iraqi Freedom and Operation Enduring Freedom combat casualties from October 2001 to June 2011 who died from injury in the deployed environment. The autopsy records, perimortem records, photographs on file, and Mortality Trauma Registry of the Armed Forces Medical Examiner Service were used to compile mechanism of injury, cause of injury, medical intervention performed, Abbreviated Injury Scale (AIS) score, and Injury Severity Score (ISS) on all lethal injuries. All data were used by the expert panel for the conduct of the potential for injury survivability assessment of this study. RESULTS For the study interval between October 2001 and June 2011, 4,596 battlefield fatalities were reviewed and analyzed. The stratification of mortality demonstrated that 87.3% of all injury mortality occurred in the pre-MTF environment. Of the pre-MTF deaths, 75.7% (n = 3,040) were classified as nonsurvivable, and 24.3% (n = 976) were deemed potentially survivable (PS). The injury/physiologic focus of PS acute mortality was largely associated with hemorrhage (90.9%). The site of lethal hemorrhage was truncal (67.3%), followed by junctional (19.2%) and peripheral-extremity (13.5%) hemorrhage. CONCLUSION Most battlefield casualties died of their injuries before ever reaching a surgeon. As most pre-MTF deaths are nonsurvivable, mitigation strategies to impact outcomes in this population need to be directed toward injury prevention. To significantly impact the outcome of combat casualties with PS injury, strategies must be developed to mitigate hemorrhage and optimize airway management or reduce the time interval between the battlefield point of injury and surgical intervention. Understanding battlefield mortality is a vital component of the military trauma system. Emphasis on this analysis should be placed on trauma system optimization, evidence-based improvements in Tactical Combat Casualty Care guidelines, data-driven research, and development to remediate gaps in care and relevant training and equipment enhancements that will increase the survivability of the fighting force.

Military Application of Tranexamic Acid in Trauma Emergency Resuscitation (MATTERs) Study

OBJECTIVES To characterize contemporary use of tranexamic acid (TXA) in combat injury and to assess the effect of its administration on total blood product use, thromboembolic complications, and mortality. DESIGN Retrospective observational study comparing TXA administration with no TXA in patients receiving at least 1 unit of packed red blood cells. A subgroup of patients receiving massive transfusion (≥10 units of packed red blood cells) was also examined. Univariate and multivariate regression analyses were used to identify parameters associated with survival. Kaplan-Meier life tables were used to report survival. SETTING A Role 3 Echelon surgical hospital in southern Afghanistan. PATIENTS A total of 896 consecutive admissions with combat injury, of which 293 received TXA, were identified from prospectively collected UK and US trauma registries. MAIN OUTCOME MEASURES Mortality at 24 hours, 48 hours, and 30 days as well as the influence of TXA administration on postoperative coagulopathy and the rate of thromboembolic complications. RESULTS The TXA group had lower unadjusted mortality than the no-TXA group (17.4% vs 23.9%, respectively; P = .03) despite being more severely injured (mean [SD] Injury Severity Score, 25.2 [16.6] vs 22.5 [18.5], respectively; P < .001). This benefit was greatest in the group of patients who received massive transfusion (14.4% vs 28.1%, respectively; P = .004), where TXA was also independently associated with survival (odds ratio = 7.228; 95% CI, 3.016-17.322) and less coagulopathy (P = .003). CONCLUSIONS The use of TXA with blood component-based resuscitation following combat injury results in improved measures of coagulopathy and survival, a benefit that is most prominent in patients requiring massive transfusion. Treatment with TXA should be implemented into clinical practice as part of a resuscitation strategy following severe wartime injury and hemorrhage.

A Clinical Series of Resuscitative Endovascular Balloon Occlusion of the Aorta for Hemorrhage Control and Resuscitation

BACKGROUND A requirement for improved methods of hemorrhage control and resuscitation along with the translation of endovascular specialty skills has resulted in reappraisal of resuscitative endovascular balloon occlusion of the aorta (REBOA) for end-stage shock. The objective of this report was to describe implementation of REBOA in civilian trauma centers. METHODS Descriptive case series of REBOA (December 2012 to March 2013) used in scenarios of end-stage hemorrhagic shock at the University of Maryland, R. Adams Cowley Shock Trauma Center, Baltimore, Maryland, and Herman Memorial Hospital, The Texas Trauma Institute, Houston, Texas. RESULTS REBOA was performed by trauma and acute care surgeons for blunt (n = 4) and penetrating (n = 2) mechanisms. Three cases were REBOA in the descending thoracic aorta (Zone I) and three in the infrarenal aorta (Zone III). Mean (SD) systolic blood pressure at the time of REBOA was 59 (27) mm Hg, and mean (SD) base deficit was 13 (5). Arterial access was accomplished using both direct cutdown (n = 3) and percutaneous (n = 3) access to the common femoral artery. REBOA resulted in a mean (SD) increase in blood pressure of 55 (20) mm Hg, and the mean (SD) aortic occlusion time was 18 (34) minutes. There were no REBOA-related complications, and there was no hemorrhage-related mortality. CONCLUSION REBOA is a feasible and effective means of proactive aortic control for patients in end-stage shock from blunt and penetrating mechanisms. With available technology, this method of resuscitation can be performed by trauma and acute care surgeons who have benefited from instruction on a limited endovascular skill set. Future work should be aimed at devices that allow easy, fluoroscopy-free access and studies to define patients most likely to benefit from this procedure. LEVEL OF EVIDENCE Therapeutic study, level V.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) as an adjunct for hemorrhagic shock.

Temporary occlusion of the aorta as an operative method to increase proximal or central perfusion to the heart and brain in the setting of shock is not new.1 Resuscitative aortic occlusion with a balloon was reported as early as the Korean War and has been described in more recent publications.2–5 Despite potential advantages over thoracotomy with aortic clamping, resuscitative endovascular balloon occlusion of the aorta (REBOA) for trauma has not been widely adopted. Broader application of this procedure may have lagged because of latent technology, a poorly understood skill set, or anticipated ineffectiveness of the technique. However, the recent evolution of endovascular technology and its clear benefit in managing vascular disease such as ruptured abdominal aortic aneurysm suggest that a reappraisal of this technique for trauma is needed. The objective of this report is to provide a technical description of REBOA. To simplify, this maneuver can be considered in the following five steps each with specific procedural considerations (Table 1):

Inflammatory aortic aneurysms. A clinical review with new perspectives in pathogenesis.

OBJECTIVE The authors present a review of abdominal aortic aneurysms (AAAs) and to examine the literature on the diagnosis, operative management, and long-term survival of patients with inflammatory AAAs. Furthermore, to review current theories on the cause of inflammatory AAAs and present recent studies that provoke new thought on the cause of these aneurysms. BACKGROUND DATA Inflammatory AAAs represent 3% to 10% of all AAAs and present the surgical team with a unique challenge. Progress has occurred in the technical approach to these aneurysms, and operative morbidity and mortality have been reduced. However, the pathogenesis remains an enigma. Recent studies raise questions regarding the influence of tobacco and genetic factors that accentuate an antigen-driven inflammatory response. METHODS The authors conduct a review of the literature on both noninflammatory and inflammatory AAAs. RESULTS Review of the literature of inflammatory AAAs reveals advancement in the definition, diagnosis, management, and long-term survival of patients with inflammatory AAAs. This review found an evolution in thought regarding the cause of inflammatory AAAs. In contrast to initial reports describing a distinct clinical entity, recent evidence suggests that inflammatory AAAs arise from the same causal stimulus responsible for noninflammatory AAAs. Finally, recent studies show an influence of tobacco and genetic factors on the pathogenesis. CONCLUSIONS The literature supports the theory that inflammatory AAAs arise from the same or similar antigenic stimulus which is responsible for the noninflammatory AAA. Genetic and chemical factors such as tobacco use predispose certain persons to the development of noninflammatory AAAs and others to develop the extreme end of an inflammatory spectrum, the inflammatory AAA. Furthermore, inflammatory AAAs can be managed with the same operative morbidity, mortality, and long-term survival as noninflammatory AAAs.

Endovascular balloon occlusion of the aorta is superior to resuscitative thoracotomy with aortic clamping in a porcine model of hemorrhagic shock

BACKGROUND Noncompressible torso hemorrhage is the leading cause of potentially preventable death on the modern battlefield. The objective of this study is to characterize resuscitative aortic balloon occlusion (BO) compared to thoracotomy with aortic clamping in a model of hemorrhagic shock. METHODS A total of 18 swine (3 groups; 6 animals/group) were used in this study. Swine in class IV shock underwent no aortic occlusion (NO), thoracotomy and clamp occlusion (CO), or endovascular BO. Animals in the NO group underwent direct placement of a temporary vascular shunt (TVS) at the injury site, whereas animals in the CO and BO groups underwent aortic occlusion before TVS placement. Hemodynamic and physiologic measures were collected. RESULTS The central aortic pressure, carotid blood flow and brain oxygenation as measured by oximetry increased in the CO and BO groups compared to the NO group (P < .05). During resuscitation, the BO group was less acidotic than the CO group (pH,7.35 vs 7.24; P < .05) with a lower serum lactate level (4.27 vs 6.55; P < .05) and pCO2 level (43.5 vs 49.9; P < .05). During resuscitation, the BO group required less fluid (667 mL vs 2,166 mL; P < .05) and norepinephrine (0 mcg vs 52.1 mcg; P < .05) than the CO group. CONCLUSION Resuscitative aortic BO increases central perfusion pressures with less physiologic disturbance than thoracotomy with aortic clamping in a model of hemorrhagic shock. Endovascular BO of the aorta should be explored further as an option in the management of noncompressible torso hemorrhage.

The Epidemiology of Vascular Injury in the Wars in Iraq and Afghanistan

Background:Blood vessel trauma leading to hemorrhage or ischemia presents a significant cause of morbidity and mortality after battlefield injury. The objective of this study is to characterize the epidemiology of vascular injury in the wars of Iraq and Afghanistan, including categorization of anatomic patterns, mechanism, and management of casualties. Methods:The Joint Theater Trauma Registry was interrogated (2002–2009) for vascular injury in US troops to identify specific injury (group 1) and operative intervention (group 2) groups. Battle-related injuries (nonreturn to duty) were used as the denominator to establish injury rates. Mechanism of injury was compared between theaters of war and the management strategies of ligation versus revascularization (repair and interposition grafting) reported. Results:Group 1 included 1570 Troops injured in Iraq (OIF) (n = 1390) and Afghanistan (OEF) (n = 180). Mechanism included explosive (73%), gunshot (27%), and other (<1%) with explosive more common in OIF than OEF (P < 0.05). During this period, 13,076 battle-related injuries occurred resulting in a specific rate of 12% (1570 of 13,076), which was higher in OIF than OEF (12.5% vs 9% respectively; P < 0.05). Of group 1, 60% (n = 940) sustained injury to major or proximal vessels and 40% (n = 630) to minor or distal vessels (unknown vessel, n = 27). Group 2 (operative) comprised 1212 troops defining an operative rate of 9% (1212 of 13,076) and included ligation (n = 660; 54%) or repair (n = 552; 46%). Peak rates in OIF and OEF occurred in November 2004 (15%) and August 2009 (11%), respectively and correlated with combat operational tempo. Conclusion:The rate of vascular injury in modern combat is 5 times that reported in previous wars and varies according to theater of war, mechanism of injury and operational tempo. Methods of reconstruction are now applied to nearly half of the vascular injuries and should be a focus of training for combat surgery. Selective ligation of vascular injury remains an important management strategy, especially for minor or distal vessel injuries.

Effect of temporary shunting on extremity vascular injury: An outcome analysis from the Global War on Terror vascular injury initiative

OBJECTIVE Extremity vascular injury during the current war has been defined by anecdotal description and case series. These reports focused on estimation of short-term limb viability and technical description of commonly used adjuncts. Temporary vascular shunting (TVS) has been advocated in current care structures, yet mostly due to war environments, broader statistical scrutiny is lacking. This studys purpose is to provide perspective on TVSs impact on limb salvage, and estimate longer-term freedom from amputation. METHODS Data from the Joint Theater Trauma Registry (JTTR), Balad Vascular Registry (BVR), Walter Reed Vascular Registry (WRVR), electronic medical records, and patient interviews were collected on American Troops sustaining extremity vascular injury from June 2003 through December 2007. Those in whom arterial TVS utilization was identified comprise the TVS group. These were compared with controls with similar injury date and anatomic location managed without TVS. Descriptive statistics were employed establishing overall univariate predictors of amputation and comparison between groups. Proportional-hazards modeling, with propensity score adjustment for systemic injury severity and Level 2 care, characterized risk factors of limb loss and effect of TVS. Freedom from amputation was estimated using Kaplan Meier log-rank methods. RESULTS Cases and controls consisted of 64 and 61 extremity arterial injuries, respectively. Mean follow-up was 22 months (range: 1-54 months). The TVS group was more severely injured (mean injury severity score [ISS]: 18 [SD = 10] TVS vs. 15 [SD = 10] control, P = .05) and more likely to receive Level 2 care (TVS: 26%; control: 10%, P = .02). Overall, a total of 26 amputations occurred (21%). Penetrating blasts, compared with gunshot wounds, were associated with amputation (30% vs. 6%, P = .002). After propensity score adjustment, use of TVS suggested a reduced risk of amputation (relative risk [RR] = 0.47; 95% confidence interval [CI] [0.18-1.19]; P = .11). Venous repair was associated with limb salvage (RR = 0.2; 95% CI [0.04-0.99], P = .05). Associated fracture (RR = 5.0; 95% CI [1.45-17.28], P = .01), and elevated mangled extremity severity score (MESS) ([MESS 5-7] RR = 3.5, 95% CI [0.97-12.36], P = .06; [MESS 8-12] RR = 16.4; 95% CI (3.79-70.79), P < .001) predicted amputation. Amputation-free survival was 78% in the TVS group and 77% in the control group at three years (P = .5). CONCLUSION Temporary vascular shunting used as a damage control adjunct in management of wartime extremity vascular injury does not lead to worse outcomes. Benefit from TVS is suggested, but not statistically significant. Injury specific variables of venous ligation, associated fracture, and penetrating blast mechanism are associated with amputation. Amputation-free survival after vascular injury in Operation Iraqi Freedom is 79% at three years. Further studies to statistically define any possible benefits of TVS are needed.

Association of cryoprecipitate and tranexamic acid with improved survival following wartime injury: findings from the MATTERs II Study

OBJECTIVE To quantify the impact of fibrinogen-containing cryoprecipitate in addition to the antifibrinolytic tranexamic acid on survival in combat injured. DESIGN Retrospective observational study comparing the mortality of 4 groups: tranexamic acid only, cryoprecipitate only, tranexamic acid and cryoprecipitate, and neither tranexamic acid nor cryoprecipitate. To balance comparisons, propensity scores were developed and added as covariates to logistic regression models predicting mortality. SETTING A Role 3 Combat Surgical Hospital in southern Afghanistan. PATIENTS A total of 1332 patients were identified from prospectively collected U.K. and U.S. trauma registries who required 1 U or more of packed red blood cells and composed the following groups: tranexamic acid (n = 148), cryoprecipitate (n = 168), tranexamic acid/cryoprecipitate (n = 258), and no tranexamic acid/cryoprecipitate (n = 758). MAIN OUTCOME MEASURE In-hospital mortality. RESULTS Injury severity scores were highest in the cryoprecipitate (mean [SD], 28.3 [15.7]) and tranexamic acid/cryoprecipitate (mean [SD], 26 [14.9]) groups compared with the tranexamic acid (mean [SD], 23.0 [19.2]) and no tranexamic acid/cryoprecipitate (mean [SD], 21.2 [18.5]) (P < .001) groups. Despite greater Injury Severity Scores and packed red blood cell requirements, mortality was lowest in the tranexamic acid/cryoprecipitate (11.6%) and tranexamic acid (18.2%) groups compared with the cryoprecipitate (21.4%) and no tranexamic acid/cryoprecipitate (23.6%) groups. Tranexamic acid and cryoprecipitate were independently associated with a similarly reduced mortality (odds ratio, 0.61; 95% CI, 0.42-0.89; P = .01 and odds ratio, 0.61; 95% CI, 0.40-0.94; P = .02, respectively). The combined tranexamic acid and cryoprecipitate effect vs. neither in a synergy model had an odds ratio of 0.34 (95% CI, 0.20-0.58; P < .001), reflecting nonsignificant interaction (P = .21). CONCLUSIONS Cryoprecipitate may independently add to the survival benefit of tranexamic acid in the seriously injured requiring transfusion. Additional study is necessary to define the role of fibrinogen in resuscitation from hemorrhagic shock.

Aortic balloon occlusion is effective in controlling pelvic hemorrhage

BACKGROUND The objective of this study was to evaluate the efficacy of resuscitative endovascular aortic balloon occlusion (REBOA) of the distal aorta in a porcine model of pelvic hemorrhage. METHODS Swine were entered into three phases of study: injury (iliac artery), hemorrhage (45 s), and intervention (180 min). Three groups were studied: no intervention (NI, n = 7), a kaolin-impregnated gauze (Combat Gauze) (CG, n = 7), or REBOA (n = 7). The protocol was repeated with a dilutional coagulopathy (CG-C, n = 7, and REBOA-C, n = 7). Measures of physiology, rates of hemorrhage, and mortality were recorded. RESULTS Rate of hemorrhage was greatest in the NI group, followed by the REBOA and CG groups (822 ± 415 mL/min versus 11 ± 13 and 0.2 ± 0.4 mL/min respectively; P < 0.001). MAP following intervention (at 15 min) was the same in the CG and REBOA groups and higher than in the NI group (70 ± 4 and 70 ± 11 mm Hg versus 5 ± 13 mm Hg respectively; P < 0.001). There was 100% mortality in the NI group, with no deaths in the CG or REBOA group. In the setting of coagulopathy, the rate of bleeding was higher in the CG-C versus the REBOA-C group (229 ± 295 mL/min versus 20 ± 7 mL/min, P = 0.085). MAP following intervention (15 min) was higher in the REBOA-C than the CG-C group (71 ± 12 mm Hg versus 28 ± 31 mm Hg; P = 0.005). There were 5 deaths (71.4%) in the CG-C group, but none in the REBOA-C group (P = 0.010). CONCLUSION Balloon occlusion of the aorta is an effective method to control pelvic arterial hemorrhage. This technique should be further developed as an adjunct to manage noncompressible pelvic hemorrhage.