Lorne H. Blackbourne

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.

Died of Wounds on the Battlefield: Causation and Implications for Improving Combat Casualty Care

BACKGROUND Understanding the epidemiology of death after battlefield injury is vital to combat casualty care performance improvement. The current analysis was undertaken to develop a comprehensive perspective of deaths that occurred after casualties reached a medical treatment facility. METHODS Battle injury died of wounds (DOW) deaths that occurred after casualties reached a medical treatment facility from October 2001 to June 2009 were evaluated by reviewing autopsy and other postmortem records at the Office of the Armed Forces Medical Examiners (OAFME). A panel of military trauma experts classified the injuries as nonsurvivable (NS) or potentially survivable (PS), in consultation with an OAFME forensic pathologist. Data including demographics, mechanism of injury, physiologic and laboratory variables, and cause of death were obtained from the Joint Theater Trauma Registry and the OAFME Mortality Trauma Registry. RESULTS DOW casualties (n = 558) accounted for 4.56% of the nonreturn to duty battle injuries over the study period. DOW casualties were classified as NS in 271 (48.6%) cases and PS in 287 (51.4%) cases. Traumatic brain injury was the predominant injury leading to death in 225 of 271 (83%) NS cases, whereas hemorrhage from major trauma was the predominant mechanism of death in 230 of 287 (80%) PS cases. In the hemorrhage mechanism PS cases, the major body region bleeding focus accounting for mortality were torso (48%), extremity (31%), and junctional (neck, axilla, and groin) (21%). Fifty-one percent of DOW casualties presented in extremis with cardiopulmonary resuscitation upon presentation. CONCLUSIONS Hemorrhage is a major mechanism of death in PS combat injuries, underscoring the necessity for initiatives to mitigate bleeding, particularly in the prehospital environment.

Eliminating Preventable Death on the Battlefield

OBJECTIVE To evaluate battlefield survival in a novel command-directed casualty response system that comprehensively integrates Tactical Combat Casualty Care guidelines and a prehospital trauma registry. DESIGN Analysis of battle injury data collected during combat deployments. SETTING Afghanistan and Iraq from October 1, 2001, through March 31, 2010. PATIENTS Casualties from the 75th Ranger Regiment, US Army Special Operations Command. MAIN OUTCOME MEASURES Casualties were scrutinized for preventable adverse outcomes and opportunities to improve care. Comparisons were made with Department of Defense casualty data for the military as a whole. RESULTS A total of 419 battle injury casualties were incurred during 7 years of continuous combat in Iraq and 8.5 years in Afghanistan. Despite higher casualty severity indicated by return-to-duty rates, the regiments rates of 10.7% killed in action and 1.7% who died of wounds were lower than the Department of Defense rates of 16.4% and 5.8%, respectively, for the larger US military population (P = .04 and P = .02, respectively). Of 32 fatalities incurred by the regiment, none died of wounds from infection, none were potentially survivable through additional prehospital medical intervention, and 1 was potentially survivable in the hospital setting. Substantial prehospital care was provided by nonmedical personnel. CONCLUSIONS A command-directed casualty response system that trains all personnel in Tactical Combat Casualty Care and receives continuous feedback from prehospital trauma registry data facilitated Tactical Combat Casualty Care performance improvements centered on clinical outcomes that resulted in unprecedented reduction of killed-in-action deaths, casualties who died of wounds, and preventable combat death. This data-driven approach is the model for improving prehospital trauma care and casualty outcomes on the battlefield and has considerable implications for civilian trauma systems.

Impact of Plasma Transfusion in Trauma Patients Who Do Not Require Massive Transfusion

BACKGROUND For trauma patients requiring massive blood transfusion, aggressive plasma usage has been demonstrated to confer a survival advantage. The aim of this study was to evaluate the impact of plasma administration in nonmassively transfused patients. STUDY DESIGN Trauma patients admitted to a Level I trauma center (2000-2005) requiring a nonmassive transfusion (<10 U packed RBC [PRBC] within 12 hours of admission) were identified retrospectively. Propensity scores were calculated to match and compare patients receiving plasma in the first 12 hours with those who did not. RESULTS The 1,716 patients (86.1% of 1,933 who received PRBC transfusion) received a nonmassive transfusion. After exclusion of 31 (1.8%) early deaths, 284 patients receiving plasma were matched to patients who did not. There was no improvement in survival with plasma transfusion (17.3% versus 14.1%; p = 0.30) irrespective of the plasma-to-PRBC ratio achieved. However, the overall complication rate was significantly higher for patients receiving plasma (26.8% versus 18.3%, odds ratio [OR] = 1.7; 95% CI, 1.1-2.4; p = 0.016). As the volume of plasma increased, an increase in complications was seen, reaching 37.5% for patients receiving >6 U. The ARDS rate specifically was also significantly higher in patients receiving plasma (9.9% versus 3.5%, OR = 3.0; 95% CI, 1.4-6.2; p = 0.004]. Patients receiving >6 U plasma had a 12-fold increase in ARDS, a 6-fold increase in multiple organ dysfunction syndrome, and a 4-fold increase in pneumonia and sepsis. CONCLUSIONS For nonmassively transfused trauma patients, plasma administration was associated with a substantial increase in complications, in particular ARDS, with no improvement in survival. An increase in multiple organ dysfunction, pneumonia, and sepsis was likewise seen as increasing volumes of plasma were transfused. The optimal trigger for initiation of a protocol for aggressive plasma infusion warrants prospective evaluation.

Coronary revascularization rather than cardiac transplantation for chronic ischemic cardiomyopathy.

Patients with very poor ventricular function have been thought to be highly vulnerable to elective myocardial revascularization. Ischemic cardiomyopathy is now the major indication for cardiac transplantation. The 2-year survival of medically treated patients with ejection fractions less than 20%, but who are not sufficiently symptomatic for cardiac transplantation, is less than 25%. At our institution we have taken an aggressive approach by using myocardial revascularization for chronic ischemic cardiomyopathy. Between 1983 and 1988, 39 patients with preoperative ejection fractions less than 20% underwent coronary artery bypass. Patients were excluded if they had valvular heart disease other than mild to moderate mitral regurgitation, required resection of a left ventricular aneurysm, or required emergency operation for acute coronary occlusion. Mean age was 63.3 years (range, 43 to 80 years) and 31 were men. Mean preoperative ejection fraction was 18.3% (range, 10% to 20%) and the mean preoperative left ventricular end diastolic pressure was 22 mm Hg (range, 8 mm Hg to 38 mm Hg). There was one operative death (2.6%). Mean follow-up was 21 months (range, 3 to 60 months) with eight late deaths (a total mortality rate of 21%). Seven deaths were due to arrhythmias. Three patients continued to have severe heart failure, one of whom underwent successful cardiac transplantation. By life table analysis, there was a 3-year survival rate of 83%. With the present shortage of cardiac transplant donors, myocardial revascularization for ischemic cardiomyopathy is a reasonably effective means for preserving residual ventricular function.

Ten-year analysis of transfusion in Operation Iraqi Freedom and Operation Enduring Freedom: increased plasma and platelet use correlates with improved survival.

BACKGROUND The Joint Theater Trauma Registry database, begun early in Operation Iraqi Freedom and Operation Enduring Freedom, created a comprehensive repository of information that facilitated research efforts and produced rapid changes in clinical care. New clinical practice guidelines were adopted throughout the last decade. The damage-control resuscitation clinical practice guideline sought to provide high-quality blood products in support of tissue perfusion and hemostasis. The goal was to reduce death from hemorrhagic shock in patients with severe traumatic bleeding. This 10-year review of the Joint Theater Trauma Registry database reports the military’s experience with resuscitation and coagulopathy, evaluates the effect of increased plasma and platelet (PLT)–to–red blood cell ratios, and analyzes other recent changes in practice. METHODS Records of US active duty service members at least 18 years of age who were admitted to a military hospital from March 2003 to February 2012 were entered into a database. Those who received at least one blood product (n = 3,632) were included in the analysis. Data were analyzed with respect to interactions within and between categories (demographics, admission characteristics, hospital course, and outcome). Transfusions were analyzed with respect to time, survival, and effect of increasing transfusion ratios. RESULTS Coagulopathy was prevalent upon presentation (33% with international normalized ratio ≥ 1.5), correlated with increased mortality (fivefold higher), and was associated with the need for massive transfusion. High transfusion ratios of fresh frozen plasma and PLT to red blood cells were correlated with higher survival but not decreased blood requirement. Survival was most correlated with PLT ratio, but high fresh frozen plasma ratio had an additive effect (PLT odds ratio, 0.22). CONCLUSION This 10-year evaluation supports earlier studies reporting the benefits of damage-control resuscitation strategies in military casualties requiring massive transfusion. The current analysis suggests that defects in PLT function may contribute to coagulopathy of trauma. LEVEL OF EVIDENCE Epidemiologic study, level IV.

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.

Safety Evaluation of New Hemostatic Agents, Smectite Granules, and Kaolin-Coated Gauze in a Vascular Injury Wound Model in Swine

BACKGROUND In 2007, a potent procoagulant mineral called WoundStat (WS), consisting of smectite granules, received clearance from the Food and Drug Administration for marketing in the United States for temporary treatment of external hemorrhage. Previously, we found that microscopic WS particles remained in the injured vessels that were treated, despite seemingly adequate wound debridement. Thus, we investigated the thromboembolic risk of using WS when compared with kaolin-coated gauze, Combat Gauze (CG); or regular gauze, Kerlix (KX) to treat an external wound with vascular injuries in pigs. METHODS The right common carotid artery and external jugular vein of pigs were isolated and sharply transected (50%). After 30 seconds of free bleeding, the neck wounds were packed with WS, CG, or KX and compressed until hemostasis was achieved (n = 8 per group). Wounds were debrided after 2 hours, and vascular injuries were primarily repaired with suture. Blood flow was restored after infusing 1 L of crystalloid (no heparin or aspirin) and the wounds were closed. Two hours later, computed tomographic angiography was performed, and the wounds were reopened to harvest the vessels. The brains and lungs were recovered for gross and microscopic examination after euthanasia. RESULTS No differences were found in baseline measurements. Thrombelastography showed similar hypercoagulability of the final blood samples when compared with baselines in all groups. All vessels treated with KX or CG were patent and had no thrombus or blood clot in their lumen. In contrast, seven of eight carotid arteries and six of eight jugular veins treated with WS developed large occlusive red thrombi and had no flow. Small clots and WS residues were also found in the lungs of two pigs. Histologically, significant endothelial and transmural damage was seen in WS-treated vessels with luminal thrombi and embedded WS residues. CONCLUSION WS granules caused endothelial injury and significant transmural damage to the vessels that render them nonviable for primary surgical repair. The granules can enter systemic circulation and cause distal thrombosis in vital organs. More relevant in vitro and in vivo safety tests should be required for clearance of new hemostatic agents.

Improved characterization of combat injury

BACKGROUND Combat injury patterns differ from civilian trauma in that the former are largely explosion-related, comprising multiple mechanistic and fragment injuries and high-kinetic-energy bullets. Further, unlike civilians, U.S. armed forces combatants are usually heavily protected with helmets and Kevlar body armor with ceramic plate inserts. Searchable databases providing actionable, statistically valid knowledge of body surface entry wounds and resulting organ injury severity are essential to understanding combat trauma. METHODS Two tools were developed to address these unique aspects of combat injury: (1) the Surface Wound Mapping (SWM) database and Surface Wound Analysis Tool (SWAT) software that were developed to generate 3D density maps of point-of-surface wound entry and resultant anatomic injury severity; and (2) the Abbreviated Injury Scale (AIS) 2005-Military that was developed by a panel of military trauma surgeons to account for multiple injury etiology from explosions and other high-kinetic- energy weapons. Combined data from the Joint Theater Trauma Registry, Navy/Marine Combat Trauma Registry, and the Armed Forces Medical Examiner System Mortality Trauma Registry were coded in AIS 2005-Military, entered into the SWM database, and analyzed for entrance site and wounding path. RESULTS When data on 1,151 patients, who had a total of 3,500 surface wounds and 12,889 injuries, were entered into SWM, surface wounds averaged 3.0 per casualty and injuries averaged 11.2 per casualty. Of the 3,500 surface wounds, 2,496 (71%) were entrance wounds with 6,631 (51%) associated internal injuries, with 2.2 entrance wounds and 5.8 associated injuries per casualty (some details cannot be given because of operational security). Crude deaths rates were calculated using Maximum AIS-Military. CONCLUSION These new tools have been successfully implemented to describe combat injury, mortality, and distribution of wounds and associated injuries. AIS 2005-Military is a more precise assignment of severity to military injuries. SWM has brought data from all three combat registries together into one analyzable database. SWM and SWAT allow visualization of wounds and associated injuries by region on a 3D model of the body.

Combat damage control surgery.

Background:Although the use of damage control surgery for blunt and penetrating injury has been widely reported and defined, the use of damage control surgery on the battlefield (combat damage control surgery) has not been well detailed. Discussion:Damage control surgery is now well established as the standard of care for severely injured civilian patients requiring emergent laparotomy in the United States. The civilian damage control paradigm is based on a “damage control trilogy.” This trilogy comprises an abbreviated operation, intensive care unit resuscitation, and a return to the operating room for the definitive operation. The goal of damage control surgery and the triology is avoidance of irreversible physiological insult termed the lethal triad. The lethal triad comprises the vicious cycle of hypothermia, acidosis, and coagulopathy. Although the damage control model involves the damage control trilogy, abbreviated operation, intensive care unit resuscitation, and definitive operation, all in the same surgical facility, the combat damage control paradigm must incorporate global evacuation through several military surgical facilities and involves up to ten stages to allow for battlefield evacuation, surgical operations, multiple resuscitations, and transcontinental transport. Summary:Combat damage control surgery represents many unique challenges for those who care for the severely injured patients in a combat zone.