The US military experience with THAM.

BACKGROUND: Acidosis, a part of the lethal trauma triad, occurs frequently after major combat trauma. Tris-hydroxymethyl aminomethane (THAM) has been used to effectively treat acidosis in injured casualties. No research has been conducted assessing the safety of THAM in the military combat setting. We sought to describe the US military experience with THAM administration to battlefield injury subjects. METHODS: We conducted a retrospective descriptive cohort study reviewing the trauma data from the Department of Defense Trauma Registry. US military personnel with an injury severity score greater than 15, between September 2001 and December 2014, were analyzed. Our primary outcome was the 30-day all-cause mortality among cohort treated with THAM versus those who were not. Differences between the cohort were examined using a student t-test (continuous variables), Wilcoxon Rank Sum test (ordinal variables), and chi-squared test (nominal variables). RESULTS: 4558 subjects met the inclusion criteria. 69 received THAM and 4489 did not. Casualties receiving THAM had higher mean ISS scores (33 vs. 27, p < 0.001), and required significantly higher amounts of packed red blood cells (RBCs, 37 vs. 10, p < 0.001). THAM cohort had longer ventilator and intensive care unit (ICU) days with an overall lower survival to hospital discharge. On univariable analysis, THAM was associated with lower odds of survival (OR 0.18, 95% CI 0.11-0.31) but on multivariable analysis, when controlling for confounders, THAM use was not associated with a worse odds of survival (OR 0.83, 95% CI 0.21-3.24). CONCLUSIONS: Within our combat trauma population, we were unable to detect worse 30 day mortality associated with THAM administration. Prospective investigations are needed to validate its use in critically injured combat casualties.

Preinjury statin use and thromboembolic events in trauma: a 10-year retrospective evaluation.

BACKGROUND: Traumatic injury is well known to increase the risk of venous thromboembolic events (VTEs), occurring in up to 58% of trauma patients. Statin medications have significant anti-inflammatory properties and have been shown to reduce the risk of VTE. We hypothesized that trauma patients who received statin medication before injury would have a lower incidence of VTE after injury. METHODS: A 10-y retrospective review identified all patients admitted to our trauma service with an injury severity score >9 and an intensive care unit stay of >3 d. This population was categorized as either "statin recipient" (SR) or "statin naïve," with subsequent categorical division by occurrence of VTE. Our primary outcome measure was the occurrence of documented VTE in both statin naïve and SR subjects. RESULTS: A total of 2519 trauma patients were included with 97 (3.8%) developing VTE. Pretrauma statin use in males remained as an independent predictor of VTE (odds ratio = 2.25, 95% confidence interval = 1.25-4.04, P < 0.01). The median time to VTE onset was 3 d longer in SRs (10.0 d; confidence interval = 7.3-12.7, P < 0.05). CONCLUSIONS: Pretrauma statin use does not appear to have a protective benefit of VTE prevention in trauma patients, as we have shown pretrauma SR male trauma patients to have a twofold increased incidence of VTE. However, when considering the 3 d longer median time to VTE onset found in SRs, we consider the protective benefit of statin use reported in the current literature as likely attributable to this observed delayed onset.

Association between seatbelt sign and internal injuries in the contemporary airbag era: A retrospective cohort study.

BACKGROUND: Literature predating routine availability of airbags reported an association between seatbelt signs and internal injuries. We measured this association among patients involved in motor vehicle crashes (MVCs) with airbag deployment. METHODS: We conducted a retrospective cohort study by chart review of all MVC patients presenting to our Emergency Department (ED) during 1 January 2008-30 September 2015. We included all adult MVC patients in the driver or front passenger seats with both shoulder and lap seatbelts and airbag deployment. Two trained chart abstractors recorded data regarding restraints and airbag deployment. We obtained all other data via electronic medical record abstraction including demographics, injuries, and survival. We compared the prevalence of cervicothoracic and intra-abdominopelvic injuries between patients with a documented seatbelt sign versus no seatbelt sign using a logistic regression model. RESULTS: Of 1379 MVC patients, 350 met inclusion criteria. Of these, 138 (39.4%) had a seatbelt sign. The prevalence of cervicothoracic injury was higher among subjects with a documented seatbelt sign (54.3% versus 42.9%, p=0.036) Seatbelt sign predicted cervicothoracic injury with a positive likelihood ratio of 1.3 (95% CI 1.0-1.7) and negative likelihood ratio of 0.8 (95% CI 0.7-1.0). The odds ratio of cervicothoracic injury among patients with a seatbelt sign versus no seatbelt sign was 1.58 (95% confidence interval 1.02-2.46) in the logistic regression model. There was no association between seatbelt sign and intra-abdominopelvic injury (p=0.418). CONCLUSIONS: In the setting of airbag deployment, there is an association between seatbelt sign and cervicothoracic injury but not intra-abdominopelvic injury.

Diagnostic accuracy of a novel software technology for detecting pneumothorax in a porcine model.

INTRODUCTION: Our objective was to measure the diagnostic accuracy of a novel software technology to detect pneumothorax on Brightness (B) mode and Motion (M) mode ultrasonography. METHODS: Ultrasonography fellowship-trained emergency physicians performed thoracic ultrasonography at baseline and after surgically creating a pneumothorax in eight intubated, spontaneously breathing porcine subjects. Prior to pneumothorax induction, we captured sagittal M-mode still images and B-mode videos of each intercostal space with a linear array transducer at 4cm of depth. After collection of baseline images, we placed a chest tube, injected air into the pleural space in 250mL increments, and repeated the ultrasonography for pneumothorax volumes of 250mL, 500mL, 750mL, and 1000mL. We confirmed pneumothorax with intrapleural digital manometry and ultrasound by expert sonographers. We exported collected images for interpretation by the software. We treated each individual scan as a single test for interpretation by the software. RESULTS: Excluding indeterminate results, we collected 338M-mode images for which the software demonstrated a sensitivity of 98% (95% confidence interval [CI] 92-99%), specificity of 95% (95% CI 86-99), positive likelihood ratio (LR+) of 21.6 (95% CI 7.1-65), and negative likelihood ratio (LR-) of 0.02 (95% CI 0.008-0.046). Among 364 B-mode videos, the software demonstrated a sensitivity of 86% (95% CI 81-90%), specificity of 85% (81-91%), LR+ of 5.7 (95% CI 3.2-10.2), and LR- of 0.17 (95% CI 0.12-0.22). CONCLUSIONS: This novel technology has potential as a useful adjunct to diagnose pneumothorax on thoracic ultrasonography.

The Effect of Hematocrit on Platelet Adhesion: Experiments and Simulations.

The volume fraction of red blood cells (RBCs) in a capillary affects the degree to which platelets are promoted to marginate to near a vessel wall and form blood clots. In this work we investigate the relationship between RBC hematocrit and platelet adhesion activity. We perform experiments flowing blood samples through a microfluidic channel coated with type 1 collagen and observe the rate at which platelets adhere to the wall. We compare these results with three-dimensional boundary integral simulations of a suspension of RBCs and platelets in a periodic channel where platelets can adhere to the wall. In both cases, we find that the rate of platelet adhesion varies greatly with the RBC hematocrit. We observe that the relative decrease in platelet activity as hematocrit falls shows a similar profile for simulation and experiment.

Transfusion for shock in US military war casualties with and without tourniquet use.

STUDY OBJECTIVE: We assess whether emergency tourniquet use for transfused war casualties admitted to military hospitals is associated with survival. METHODS: A retrospective review of trauma registry data was made of US casualties in Afghanistan and Iraq. Patients with major limb trauma, transfusion, and tourniquet use were compared with similar patients who did not receive tourniquet use. A propensity-matching analysis was performed by stratifying for injury type and severity by tourniquet-use status. Additionally, direct comparison without propensity matching was made between tourniquet use and no-tourniquet use groups. RESULTS: There were 720 casualties in the tourniquet use and 693 in the no-tourniquet use groups. Of the 1,413 casualties, 66% (928) also had nonextremity injury. Casualties with tourniquet use had worse signs of hemorrhagic shock (admission base deficit, admission hemoglobin, admission pulse, and transfusion units required) than those without. Survival rates were similar between the 2 groups (1% difference; 95% confidence interval -2.5% to 4.2%), but casualties who received tourniquets had worse shock and received more blood products. In propensity-matched casualties, survival rates were not different (2% difference; 95% confidence interval -6.7% to 2.7%) between the 2 groups. CONCLUSION: Tourniquet use was associated with worse shock and more transfusion requirements among hospital-admitted casualties, yet those who received tourniquets had survival rates similar to those of comparable, transfused casualties who did not receive tourniquets.

U.S. Military use of tourniquets from 2001 to 2010.

OBJECTIVE: This study was conducted to associate tourniquet use and survival in casualty care over a decade of war in order to provide evidence to emergency medical personnel for the implementation and efficacy of tourniquet use in a large trauma system. METHODS: This survey is a retrospective review of data extracted from a trauma registry. The decade (2001-2010) outcome trend analysis of tourniquet use in the current wars was made in order to associate tourniquet use and survival in an observational cohort design. RESULTS: Of 4,297 casualties with extremity trauma in the total study, 30% (1,272/4,297) had tourniquet use and 70% (3,025/4,297) did not. For all 4,297 casualties, the proportion of casualties with severe or critical extremity Abbreviated Injury Scales (AIS) increased during the years surveyed (p < 0.0001); the mean annual Injury Severity Score (ISS) rose from 13 to 21. Tourniquet use increased during the decade by almost tenfold from 4 to nearly 40% (p < 0.0001). Survival for casualties with isolated extremity injury varied by injury severity; the survival rate for AIS 3 (serious) was 98%, the rate for AIS 4 (severe) was 76%, and the rate for AIS 5 (critical) was 0%. Survival rates increased for casualties with injuries amenable to tourniquets but decreased for extremity injuries too proximal for tourniquets. CONCLUSIONS: Average injury severity increased during the decade of war for casualties with extremity injury. Both tourniquet use rates and casualty survival rates rose when injuries were amenable to tourniquets.

En-route care capability from point of injury impacts mortality after severe wartime injury.

OBJECTIVE: The objective of this study is to characterize modern point-of-injury (POI) en-route care platforms and to compare mortality among casualties evacuated with conventional military retrieval (CMR) methods to those evacuated with an advanced medical retrieval (AMR) capability. BACKGROUND: Following a decade of war in Afghanistan, the impact of en-route care capabilities from the POI on mortality is unknown. METHODS: Casualties evacuated from POI to one level III facility in Afghanistan (July 2008-March 2012) were identified from UK and US trauma registries. Groups comprised those evacuated by a medically qualified provider-led, AMR and those by a medic-led CMR capability. Outcomes were compared per incremental Injury Severity Score (ISS) bins. RESULTS: Most casualties (n = 1054; 61.2%) were in the low-ISS (1-15) bracket in which there was no difference in en-route care time or mortality between AMR and CMR. Casualties in the mid-ISS bracket (16-50) (n = 583; 33.4%) experienced the same median en-route care time (minutes) on AMR and CMR platforms [78 (58) vs 75 (93); P = 0.542] although those on AMR had shorter time to operation [110 (95) vs 117 (126); P < 0.001]. In this mid-ISS bracket, mortality was lower in the AMR than in the CMR group (12.2% vs 18.2%; P = 0.035). In the high-ISS category (51-75) (n = 75; 4.6%), time to operation was lower in the AMR than the CMR group (66 ± 77 vs 113 ± 122; P = 0.013) but there was no difference in mortality. CONCLUSIONS: This study characterizes en-route care capabilities from POI in modern combat. Conventional platforms are effective in most casualties with low injury severity. However, a definable injury severity exists for which evacuation with an AMR capability is associated with improved survival.

Anatomic distribution and mortality of arterial injury in the wars in Afghanistan and Iraq with comparison to a civilian benchmark.

OBJECTIVE: The purpose of this study was to examine the anatomic distribution and associated mortality of combat-related vascular injuries comparing them to a contemporary civilian standard. DESIGN: The Joint Trauma Theater Registry (JTTR) was queried to identify patients with major compressible arterial injury (CAI) and noncompressible arterial injury (NCAI) sites, and their outcomes, among casualties in Iraq and Afghanistan from 2003 to 2006. The National Trauma Data Bank (NTDB) was then queried over the same time frame to identify civilian trauma patients with similar arterial injuries. Propensity score-based matching was used to create matched patient cohorts from both populations for analysis. RESULTS: Registry queries identified 380 patients from the JTTR and 7020 patients from the NTDB who met inclusion criteria. Propensity score matching for age, elevated Injury Severity Score (ISS; >15), and hypotension on arrival (systolic blood pressure [SBP] <90) resulted in 167 matched patients from each registry. The predominating mechanism of injury among matched JTTR patients was explosive events (73.1%), whereas penetrating injury was more common in the NTDB group (61.7%). In the matched cohorts, the incidence of NCAI did not differ (22.2% JTTR vs 26.6% NTDB; P = .372), but the NTDB patients had a higher incidence of CAI (73.7% vs 59.3%; P = .005). The JTTR cohort was also found to have a higher incidence of associated venous injury (57.5% vs 23.4%; P < .001). Overall, the matched JTTR cohort had a lower mortality than NTDB counterparts (4.2% vs 12.6%; P = .006), a finding that was also noted among patients with NCAI (10.8% vs 36.4%; P = .008). There was no difference in mortality between matched JTTR and NTDB patients with CAI overall (2.0% vs 4.1%; P = .465), or among those presenting with Glasgow Coma Scale (GCS) <8 (28.6% vs 40.0%; P = 1.00) or shock (SBP <90; 10.5% vs 7.7%; P = 1.00). The JTTR mortality rate among patients with CAI was, however, lower among patients with ISS >15 compared with civilian matched counterparts (10.7% vs 42.4%; P = .006). CONCLUSIONS: Mortality of injured service personnel who reach a medical treatment facility after major arterial injury compares favorably to a matched civilian standard. Acceptable mortality rates within the military cohort are related to key aspects of an organized Joint Trauma System, including prehospital tactical combat casualty care, rapid medical evacuation to forward surgical capability, and implementation of clinical practice guidelines. Aspects of this comprehensive combat casualty care strategy may translate and be of value to management of arterial injury in the civilian sector.

Coagulopathy and shock on admission is associated with mortality for children with traumatic injuries at combat support hospitals.

OBJECTIVE: In adults, early traumatic coagulopathy and shock are both common and independently associated with mortality. There are little data regarding both the incidence and association of early coagulopathy and shock on outcomes in pediatric patients with traumatic injuries. Our objective was to determine whether coagulopathy and shock on admission are independently associated with mortality in children with traumatic injuries. METHODS: A retrospective review of the Joint Theater Trauma Registry from U.S. combat support hospitals in Iraq and Afghanistan from 2002 to 2009 was performed. Coagulopathy was defined as an international normalized ratio of ≥1.5 and shock as a base deficit of ≥6. Laboratory values were measured on admission. Primary outcome was inhospital mortality. Univariate analyses were performed on all admission variables followed by reverse stepwise multivariate logistic regression to determine independent associations. SETTING: Combat support hospitals in Iraq and Afghanistan. PATIENTS: Patients <18 yrs of age with Injury Severity Score, international normalized ratio, base deficit, and inhospital mortality were included. Of 1998 in the cohort, 744 (37%) had a complete set of data for analysis. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: The incidence of early coagulopathy and shock were 27% and 38.3% and associated with mortality of 22% and 16.8%, respectively. After multivariate logistic regression, early coagulopathy had an odds ratio of 2.2 (95% confidence interval 1.1-4.5) and early shock had an odds ratio of 3.0 (95% confidence interval 1.2-7.5) for mortality. Patients with coagulopathy and shock had an odds ratio of 3.8 (95% confidence interval 2.0-7.4) for mortality. CONCLUSIONS: In children with traumatic injuries treated at combat support hospitals, coagulopathy and shock on admission are common and independently associated with a high incidence of inhospital mortality. Future studies are needed to determine whether more rapid and accurate methods of measuring coagulopathy and shock as well as if early goal-directed treatment of these states can improve outcomes in children.

Prehospital burn management in a combat zone.

OBJECTIVE: The purpose of this article is to provide a descriptive study of the management of burns in the prehospital setting of a combat zone. METHODS: A retrospective chart review was performed of U.S. casualties with >20% total-body-surface-area thermal burns, transported from the site of injury to Ibn Sina Combat Support Hospital (CSH) between January 1, 2006, and August 30, 2009. RESULTS: Ibn Sina CSH received 225 burn casualties between January 2006 and August 2009. Of these, 48 met the inclusion criteria. The mean Injury Severity Score was 31.7 (range 4 to 75). Prehospital vascular access was obtained in 24 casualties (50%), and 20 of the casualties received fluid resuscitation. Out of the 48 casualties enrolled, 28 (58.3%) did not receive prehospital fluid resuscitation. Of the casualties who received fluid resuscitation, nearly all received volumes in excess of the guidelines established by the American Burn Association and those recommended by the Committee for Tactical Combat Casualty Care. With regard to pain management in the prehospital setting, 13 casualties (27.1%) received pain medication. CONCLUSIONS: With regard to the prehospital fluid resuscitation of primary thermal injury in the combat zone, two extremes were noted. The first group did not receive any fluid resuscitation; the second group was resuscitated with fluid volumes higher than those expected if established guidelines were utilized. Pain management was not uniformly provided to major burn casualties, even in several with vascular access. These observations support improved education of prehospital personnel serving in a combat zone.

Survey of trauma registry data on tourniquet use in pediatric war casualties.

OBJECTIVES: Previously, we reported on the use of emergency tourniquets to stop bleeding in war casualties, but virtually all the data were from adults. Because no pediatric-specific cohort of casualties receiving emergency tourniquets existed, we aimed to fill knowledge gaps on the care and outcomes of this group by surveying data from a trauma registry to refine device designs and clinical training. METHODS: A retrospective review of data from a trauma registry yielded an observational cohort of 88 pediatric casualties at US military hospitals in theater on whom tourniquets were used from May 17, 2003, to December 25, 2009. RESULTS: Of the 88 casualties in the study group, 72 were male and 16 were female patients. Ages averaged 11 years (median, 11 years; range, 4-17 years). There were 7 dead and 81 survivor outcomes for a trauma survival rate of 93%. Survivor and dead casualties were similar in all independent variables measured except hospital stay duration (median, 5 days and 1 day, respectively). Six casualties (7%) had neither extremity nor external injury in that they had no lesion indicating tourniquet use. CONCLUSIONS: The survival rate of the present study's casualties is similar to that of 3 recent large nonpediatric-specific studies. Although current emergency tourniquets were ostensibly designed for modern adult soldiers, tourniquet makers, perhaps unknowingly, produced tourniquets that fit children. The rate of unindicated tourniquets, 7%, implied that potential users need better diagnostic training. LEVELS OF EVIDENCE: Level 4; case series, therapeutic study.

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.

Analysis of life-saving interventions performed by out-of-hospital combat medical personnel.

BACKGROUND: To analyze casualties from the Camp Eagle Study, focusing on life-saving interventions (LSI) and potentially survivable deaths. METHODS: Retrospective cohort of battle casualties from a forward base engaged in urban combat in Central Iraq. Medical support included emergency medicine practitioners and combat medics with advanced training and protocols. LSI were defined as advanced airway, needle or tube thoracostomy, tourniquet, and hypotensive resuscitation with Hetastarch. Cases were assessed retrospectively for notional application of a Remote Damage Control Resuscitation protocol using blood products. RESULTS: Three hundred eighteen subjects were included. The case fatality rate was 7%. "Urgent" (55) or "priority" (88) medical evacuation was required for 45% of casualties. Sixty-one LSI were performed, in most cases by the physician or PA, with 80% on "urgent" and 9% on "priority" casualties, respectively. Among survivors requiring LSI, the percentage actually performed were airway 100%; thoracostomy 100%; tourniquet 100%; hetastarch 100%. Among nonsurvivors, these percentages were 78%, 50%, 100%, and 56%, respectively. Proximate causes of potentially survivable death were delays in airway placement and ventilation (40%), no thoracostomy (20%), and delayed evacuation resulting in hemorrhagic shock (60%). The notional Remote Damage Control Resuscitation protocol would have been appropriate in 15% of "urgent" survivors and in 26% of nonsurvivors. CONCLUSION: LSI were required by most urgent casualties, and a lack or delay in their performance was associated with increased mortality. Forward deployment of blood components may represent the next addition to LSI if logistical and scope-of-practice issues can be overcome.

Combat-related pelvis fractures in nonsurvivors.

BACKGROUND: The purpose of this study was to describe pelvic fractures and their associated injuries in service members who either died of wounds or were killed in action during Operation Iraqi Freedom and Operation Enduring Freedom and define any differences in associated injuries between penetrating versus blunt injury to the pelvis. METHODS: A review of all service members who sustained a pelvis fracture during Operation Iraqi Freedom and Operation Enduring Freedom in the year 2008 was performed. Data were recorded for analysis. RESULTS: One hundred four nonsurvivors were identified with pelvic fractures. Appropriate records, photos, and radiographs were available for 91, 70 were classified as "Not Survivable" (77%) and 21 "Potentially Survivable" (23%). Mechanisms of injury included 69 blast (76%), 14 gunshot wounds (15%), 4 motor vehicle accidents (4.5%), and 4 "other" (4.5%). Direct injury to the pelvis was penetrating in 60 (66%) and blunt in 31 (34%). Large pelvic vessel injury was observed more frequently in penetrating pelvic injuries (27%) than blunt injuries (3%). Hollow viscus abdominal injuries were more common in those with penetrating (57%) than blunt injuries (10%). There was an inverse relationship with intra-abdominal, solid organ injuries (blunt, 81%; penetrating, 55%). Head injuries were also more common in blunt pelvic injuries (blunt, 68%; penetrating, 45%), as were cardiopulmonary injuries (blunt, 84%, penetrating injuries, 57%). CONCLUSIONS: Large pelvic vessel and hollow viscus injuries occur more frequently in penetrating combat-related pelvic fractures, whereas intra-abdominal solid organ, head, and cardiopulmonary injuries are more common in blunt pelvic injuries.

Development of a standard swine hemorrhage model for efficacy assessment of topical hemostatic agents.

BACKGROUND: The diverse information of efficacy of hemostatic products, obtained from different military laboratories using different models, has made it difficult to ascertain the true benefit of new hemostatic agents in military medicine. The aim of this study was to recommend a standard hemorrhage model for efficacy testing acceptable by most investigators in the field and avoid contradictory and duplicative efforts by different laboratories. METHODS: The swine femoral artery injury model (6-mm arteriotomy) with some modifications was tested to standardize the model. The suggested modifications included no splenectomy, one-time treatment, 30 seconds free bleeding, and 5 L limit for fluid resuscitation. The model was tested with all or some of these modifications in four experimental conditions (n = 5-6 pigs per condition) using Combat Gauze (CG) as control agent. RESULTS: The primary end points including blood pressure, blood loss, and survival rates were modestly changed in the four conditions. The second experimental condition in which bleeding was treated with a single CG with 3-minute compression produced the most suitable results. The average blood loss was 99 mL/kg, and hemostasis was achieved in one-third of the pigs, which led to matching survival rate. CONCLUSION: A rigorous hemorrhage model was developed for future evaluation of new hemostatic agents and comparison with CG, the current standard of care. This model may not be suitable for testing every agent and some modifications may be necessary for specific applications. Furthermore, laboratory studies using this or similar models must be accompanied by operational testing in the field to confirm the efficacy and practical utility of selected agents when used on the battlefield.

Mechanism of injury affects acute coagulopathy of trauma in combat casualties.

BACKGROUND: Recent evidence suggests trauma involving total body tissue damage increases the acute coagulopathy of trauma (ACOT) by various mechanisms, especially in massive transfusion (MT). Our hypothesis was that MT patients injured by explosion will have a higher international normalization ratio (INR) at admission than MT patients injured by gunshot wound (GSW). METHODS: A retrospective review was performed on US military injured in Operation Iraqi Freedom/Operation Enduring Freedom from March 2003 to September 2008, who received MT (≥ 10 red blood cells in 24 hours) and had an INR on admission. Two cohorts were created based on mechanism. Admission vital signs, labs, transfusion, and mortality data were compared. RESULTS: Seven hundred fifty-one MT patients were identified. Four hundred fifty patients had admission INR and were injured by either GSW or explosion. Patients demonstrated similar injury severity scale and Glasgow Coma Scale. Patients injured by explosion presented with higher INR, greater base deficit, and more tachycardic than patients injured by GSW. Transfusion of blood products was similar between both groups. CONCLUSIONS: The primary finding of this study is that patients injured by explosion presented with a higher INR than those injured by GSW, even with similar injury severity scale. In addition, patients injured by explosion presented more tachycardic and with a greater base deficit. These findings support the theory that ACOT is affected by the amount of tissue injured. Further research is needed into the pathophysiology of ACOT because this may impact care of patients with total body tissue damage/hypoxia and improve the treatment of their coagulopathy while minimizing the attendant complications.

Impact of improved combat casualty care on combat wounded undergoing exploratory laparotomy and massive transfusion.

BACKGROUND: Studies have shown decreased mortality after improvements in combat casualty care, including increased fresh frozen plasma (FFP):red blood cell (RBC) ratios. The objective was to evaluate the evolution and impact of improved combat casualty care at different time periods of combat operations. METHODS: A retrospective review was performed at one combat support hospital in Iraq of patients requiring both massive transfusion (≥ 10 units RBC in 24 hours) and exploratory laparotomy. Patients were divided into two cohorts based on year wounded: C1 between December 2003 and June 2004, and C2 between September 2007 and May 2008. Admission data, amount of blood products and fluid transfused, and 48 hour mortality were compared. Statistical significance was set at p < 0.05. RESULTS: There was decreased mortality in C2 (47% vs. 20%). Patients arrived warmer with higher hemoglobin. They were transfused more RBC and FFP in the emergency department (5 units ± 3 units vs. 2 units ± 2 units; 3 units ± 2 units vs. 0 units ± 1 units, respectively) and received less crystalloid in operating room (3.3 L ± 2.2 L vs. 8.5 L ± 4.9 L). The FFP:RBC ratio was also closer to 1:1 in C2 (0.775 ± 0.32 vs. 0.511 ± 0.21). CONCLUSIONS: The combination of improved prehospital care, trauma systems approach, performance improvement projects, and improved transfusion or resuscitation practices have led to a 50% decrease in mortality for this critically injured population. We are now transfusing blood products in a ratio more consistent with 1 FFP to 1 RBC. Simultaneously, crystalloid use has decreased by 61%, all of which is consistent with hemostatic resuscitation principles.

Tranexamic acid for trauma patients: a critical review of the literature.

BACKGROUND: Tranexamic acid (TXA) is an antifibrinolytic that inhibits both plasminogen activation and plasmin activity, thus preventing clot break-down rather than promoting new clot formation. TXA has been used around the world to safely control bleeding since the 1960s. A large randomized trial recently conducted in >20,000 trauma patients adds to the large body of data documenting the usefulness of TXA in promoting hemostasis. METHODS: We reviewed the literature describing use of TXA in a variety of settings including trauma. RESULTS: TXA has been safely used across a wide range of clinical settings to control hemorrhage. The results of a large, randomized, placebo-controlled trial support the use of TXA to treat bleeding trauma patients. CONCLUSIONS: This inexpensive and safe drug should be incorporated into trauma clinical practice guidelines and treatment protocols. Further research on possible alternate mechanisms of action and dosing regimens for TXA should be undertaken. Concurrent to these endeavors, TXA should be adopted for use in bleeding trauma patients because it is the only drug with prospective clinical evidence to support this application.

Impact of the duration of platelet storage in critically ill trauma patients.

BACKGROUND: There is increasing evidence that the duration of red blood cell (RBC) storage negatively impacts outcomes. Data regarding prolonged storage of other blood components, however, are lacking. The aim of this study was to evaluate how the duration of platelet storage affects trauma patient outcomes. METHODS: Trauma patients admitted to a Level I trauma center requiring platelet transfusion (2006-2009) were retrospectively identified. Apheresis platelets (aPLT) containing ≥3 × 10(11) platelets/unit were used exclusively. Patients were analyzed in three groups: those who received only aPLT stored for ≤3 days, 4 days, and 5 days. The outcomes included mortality and complications (sepsis, acute respiratory distress syndrome, renal, and liver failure). RESULTS: Three hundred eighty-one patients were available for analysis (128 received aPLT ≤3 days old; 109 = 4 days old; and 144 = 5 days old). There were no significant demographic differences between groups. Patients receiving aPLT aged = 4 days had significantly higher Injury Severity Score (p = 0.022) and were more likely to have a head Abbreviated Injury Scale ≥3 (p = 0.014). There were no differences in volumes transfused or age of RBC, plasma, cryoprecipitate, or factor VIIa. After adjusting for confounders, exposure to older aPLT did not impact mortality; however, with increasing age, complications were significantly higher. The rate of sepsis, in particular, was significantly increased (5.5% for aPLT ≤3 days vs. 9.2% for aPLT = 4 days vs. 16.7% for aPLT = 5 days, adjusted p = 0.033). For acute respiratory distress syndrome and renal and liver failure, similar trends were observed. CONCLUSIONS: In critically ill trauma patients, there was a stepwise increase in complications, in particular sepsis, with exposure to progressively older platelets. Further evaluation of the underlying mechanism and methods for minimizing exposure to older platelets is warranted.