Military-to-civilian translation of battlefield innovations in operative trauma care

BACKGROUND

Historic improvements in operative trauma care have been driven by war. It is unknown whether recent battlefield innovations stemming from conflicts in Iraq/Afghanistan will follow a similar trend. The objective of this study was to survey trauma medical directors (TMDs) at level 1-3 trauma centers across the United States and gauge the extent to which battlefield innovations have shaped civilian practice in 4 key domains of trauma care.

METHODS

Domains were determined by the use of a modified Delphi method based on multiple consultations with an expert physician/surgeon panel: (1) damage control resuscitation (DCR), (2) tourniquet use, (3) use of hemostatic agents, and (4) prehospital interventions, including intraosseous catheter access and needle thoracostomy. A corresponding 47-item electronic anonymous survey was developed/pilot tested before dissemination to all identifiable TMD at level 1-3 trauma centers across the US.

RESULTS

A total of 245 TMDs, representing nearly 40% of trauma centers in the United States, completed and returned the survey. More than half (n = 127; 51.8%) were verified by the American College of Surgeons. TMDs reported high civilian use of DCR: 95.1% of trauma centers had implemented massive transfusion protocols and the majority (67.7%) tended toward 1:1:1 packed red blood cell/fresh-frozen plasma/platelets ratios. For the other 3, mixed adoption corresponded to expressed concerns regarding the extent of concomitant civilian research to support military research and experience. In centers in which policies reflecting battlefield innovations were in use, previous military experience frequently was acknowledged.

CONCLUSION

This national survey of TMDs suggests that military data supporting DCR has altered civilian practice. Perceived relevance in other domains was less clear. Civilian academic efforts are needed to further research and enhance understandings that foster improved trauma surgeon awareness of military-to-civilian translation.

Meta-analysis of prognostic factors for amputation following surgical repair of lower extremity vascular trauma

Background

Lower extremity vascular trauma (LEVT) is a major cause of amputation. A clear understanding of prognostic factors for amputation is important to inform surgical decision-making, patient counselling and risk stratification. The aim was to develop an understanding of prognostic factors for amputation following surgical repair of LEVT.

Methods

A systematic review was conducted to identify potential prognostic factors. Bayesian meta-analysis was used to calculate an absolute (pooled proportion) and relative (pooled odds ratio, OR) measure of the amputation risk for each factor.

Results

Forty-five studies, totalling 3187 discrete LEVT repairs, were included. The overall amputation rate was 10·0 (95 per cent credible interval 7·4 to 13·1) per cent. Significant prognostic factors for secondary amputation included: associated major soft tissue injury (26 versus 8 per cent for no soft tissue injury; OR 5·80), compartment syndrome (28 versus 6 per cent; OR 5·11), multiple arterial injuries (18 versus 9 per cent; OR 4·85), duration of ischaemia exceeding 6 h (24 versus 5 per cent; OR 4·40), associated fracture (14 versus 2 per cent; OR 4·30), mechanism of injury (blast 19 per cent, blunt 16 per cent, penetrating 5 per cent), anatomical site of injury (iliac 18 per cent, popliteal 14 per cent, tibial 10 per cent, femoral 4 per cent), age over 55 years (16 versus 9 per cent; OR 3·03) and sex (men 7 per cent versus women 8 per cent; OR 0·64). Shock and nerve or venous injuries were not significant prognostic factors for secondary amputation.

Conclusion

A significant proportion of patients who undergo lower extremity vascular trauma repair will require secondary amputation. This meta-analysis describes significant prognostic factors needed to inform surgical judgement, risk assessment and patient counselling.

VA Vascular Injury Study (VAVIS): VA-DoD extremity injury outcomes collaboration

BACKGROUND

Limb injuries comprise 50-60% of U.S. Service member's casualties of wars in Afghanistan and Iraq. Combat-related vascular injuries are present in 12% of this cohort, a rate 5 times higher than in prior wars. Improvements in medical and surgical trauma care, including initial in-theatre limb salvage approaches (IILS) have resulted in improved survival and fewer amputations, however, the long-term outcomes such as morbidity, functional decline, and risk for late amputation of salvaged limbs using current process of care have not been studied. The long-term care of these injured warfighters poses a significant challenge to the Department of Defense (DoD) and Department of Veterans Affairs (VA).

METHODS/DESIGN

The VA Vascular Injury Study (VAVIS): VA-DoD Extremity Injury Outcomes Collaborative, funded by the VA, Health Services Research and Development Service, is a longitudinal cohort study of Veterans with vascular extremity injuries. Enrollment will begin April, 2015 and continue for 3 years. Individuals with a validated extremity vascular injury in the Department of Defense Trauma Registry will be contacted and will complete a set of validated demographic, social, behavioral, and functional status measures during interview and online/ mailed survey. Primary outcome measures will: 1) Compare injury, demographic and geospatial characteristics of patients with IILS and identify late vascular surgery related limb complications and health care utilization in Veterans receiving VA vs. non-VA care, 2) Characterize the preventive services received by individuals with vascular repair and related outcomes, and 3) Describe patient-reported functional outcomes in Veterans with traumatic vascular limb injuries.

DISCUSSION

This study will provide key information about the current process of care for Active Duty Service members and Veterans with polytrauma/vascular injuries at risk for persistent morbidity and late amputation. The results of this study will be the first step for clinicians in VA and military settings to generate evidence-based treatment and care approaches to these injuries. It will identify areas where rehabilitation medicine and vascular specialty care or telehealth options are needed to allow for better planning, resource utilization, and improved DoD-to-VA care transitions.

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.

Endovascular therapy in trauma

The practice of medicine has experienced a revolution in the use of catheter-based or endovascular techniques to manage age-related vascular disease over the past 15 years. In many scenarios the less invasive, endovascular method is associated with reduced morbidity and mortality than the traditional open surgical approach. Although somewhat delayed, the use of endovascular approaches in the management of certain trauma scenarios has also increased dramatically. With improvements in catheter-based and imaging technologies and a broader acceptance of the value of the endovascular approach, this trend is likely to continue to the benefit of patients. The use of endovascular techniques in trauma can be considered in three broad categories: (1) large-vessel repair (e.g. covered stent repair), (2) mid- to small-vessel hemostasis (e.g. coils, plugs, and hemostatic agents), and (3) large-vessel balloon occlusion for resuscitation (e.g. resuscitative endovascular balloon occlusion of the aorta). While not exclusive, these categories provide a framework from which to consider establishing a trauma-specific endovascular inventory and performance of these techniques in the setting of severe injury. The aim of this review is to use this framework to provide a current appraisal of endovascular techniques to manage various forms: vascular injury, bleeding, and shock; including injury patterns in which an endovascular approach is established and scenarios in which it is nascent and evolving.

The inflammatory sequelae of aortic balloon occlusion in hemorrhagic shock

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a hemorrhage control and resuscitative adjunct that has been demonstrated to improve central perfusion during hemorrhagic shock. The aim of this study was to characterize the systemic inflammatory response associated and cardiopulmonary sequelae with 30, 60, and 90 min of balloon occlusion and shock on the release of interleukin 6 (IL-6) and tumor necrosis factor alpha.

MATERIALS AND METHODS

Anesthetized female Yorkshire swine (Sus scrofa, weight 70-90 kg) underwent a 35% blood volume-controlled hemorrhage followed by thoracic aortic balloon occlusion of 30 (30-REBOA, n = 6), 60 (60-REBOA, n = 8), and 90 min (90-REBOA, n = 6). This was followed by resuscitation with whole blood and crystalloid over 6 h. Animals then underwent 48 h of critical care with sedation, fluid, and vasopressor support.

RESULTS

All animals were successfully induced into hemorrhagic shock without mortality. All groups responded to aortic occlusion with a rise in blood pressure above baseline values. IL-6, as measured (picogram per milliliter) at 8 h, was significantly elevated from baseline values in the 60-REBOA and 90-REBOA groups: 289 ± 258 versus 10 ± 5; P = 0.018 and 630 ± 348; P = 0.007, respectively. There was a trend toward greater vasopressor use (P = 0.183) and increased incidence of acute respiratory distress syndrome (P = 0.052) across the groups.

CONCLUSIONS

REBOA is a useful adjunct in supporting central perfusion during hemorrhagic shock; however, increasing occlusion time and shock results in a greater IL-6 release. Clinicians must anticipate inflammation-mediated organ failure in post-REBOA use patients.

Wartime vascular injuries in the pediatric population of Iraq and Afghanistan: 2002-2011

BACKGROUND

Contemporary war-related studies focus primarily on adults with few reporting the injuries sustained in local pediatric populations. The objective of this study is to characterize pediatric vascular trauma at US military hospitals in wartime Iraq and Afghanistan.

METHODS

Review of the Department of Defense Trauma Registry (DoDTR) (2002-2011) identified patients (1-17 years old) treated at US military hospitals in Iraq and Afghanistan using ICD-9 and procedure codes for vascular injury.

RESULTS

US military hospitals treated 4402 pediatric patients between 2002 and 2011. One hundred fifty-five patients (3.5%) had a vascular injury. Mean age, gender, and injury severity score (ISS) were 11.1 ± 4.1 years, 79% male, and 34 ± 13.5, respectively. Vascular injuries were primarily from penetrating mechanisms (95.6%; 58.0% blast injury) to the extremity (65.9%), torso (25.4%), and neck (8.6%). Injuries were ligated (31%), reconstructed (63%), or observed (2%). Limb salvage rate was 95%. Mortality rate was 9%.

CONCLUSIONS

This study is the first to report vascular trauma in a pediatric population at wartime. Vascular injuries involve a high percentage of extremity and torso wounding. Torso vascular injury in children is four times lethal relative to other injury patterns, and therefore should be considered in operational planning both in the military and civilian setting regarding pediatric vascular injuries.

Prospective evaluation of the correlation between torso height and aortic anatomy in respect of a fluoroscopy free aortic balloon occlusion system

BACKGROUND

To report the lengths of key torso vascular and to develop regression models that will predict these lengths, based on an external measure of torso height (EMTH, sternum to pubis) in the development of a fluoroscopy-free balloon occlusion system for hemorrhage control.

METHODS

We conducted a prospective, observational study at a Combat Support Hospital in Southern Afghanistan using adult male patients undergoing computed tomography (CT). EMTH was recorded using a tape measure and intra-arterial distance was derived from CT imaging. Regression models to predict distance from the common femoral artery (CFA) into the middle of aortic zone I (left subclavian artery to celiac trunk) and zone III (infrarenal aorta) were developed from a random 20% of the cohort and validated by the remaining 80%.

RESULTS

Overall, 177 male patients were included with a median (interquartile range [IQR]) age of 23 (8) years. The median (IQR) lengths of aortic zone I and III were 222 (24), 31 (9), and 92 (15) mm. The mid-zone distance from the left and right CFA to zone I were 423 (27) and 418 (29) and for zone III 232 (21) and 228 (22). Linear regression models demonstrated an accuracy between 99.3% to 100% at predicting the insertion distance required to place a catheter within the middle of each aortic zone.

CONCLUSION

This study demonstrates the use of morphometric analysis in the development of a fluoroscopy-free balloon occlusion system for torso hemorrhage control. Further study in a larger population of mixed gender is required to further validate insertion models.

Morphometric analysis of torso arterial anatomy with implications for resuscitative aortic occlusion

BACKGROUND

Hemorrhage is a leading cause of death in military and civilian trauma. Despite the importance of the aorta as a site of hemorrhage control and resuscitative occlusion, detailed knowledge of its morphometry is lacking. The objective of this study was to characterize aortic morphometry in a trauma population, including quantification of distances as well as and diameters and definition of relevant aortic zones.

METHODS

Center line measures were made (Volume Viewer) from contrast computed tomography (CT) scans of male trauma patients (18-45 years). Aortic zones were defined based on branch arteries. Zone I includes left subclavian to celiac; Zone II includes celiac to caudal renal; Zone III includes caudal renal to aortic bifurcation. Zone lengths were calculated and correlated to a novel external measure of torso extent (symphysis pubis to sternal notch).

RESULTS

Eighty-eight males (mean [SD], 28 [4] years) had CT scans for the study. The median (interquartile range) lengths (mm) of Zones I, II, and III were 210 mm (202-223 mm), 33 mm (28-38 mm), and 97 mm (91-103 mm), respectively. Median aortic diameters at the left subclavian, celiac, and lowest renal arteries were 21 mm (20-23 mm), 18 mm (16-19 mm), and 15 mm (14-16 mm), respectively, and the terminal aortic diameter was 14 mm (13-15 mm). The correlation of determination for descending aortic length (all zones) against torso extend was r = 0.454.

CONCLUSION

This study provides a morphometric analysis of the aorta in a male population, demonstrating consistency of length and diameter while defining distinct axial zones. Findings suggest that center line aortic distances correlate with a simple, external measure of torso extent. Morphometric study of the aorta using CT data may facilitate the development and implementation of occlusion techniques to manage noncompressible torso, pelvic, and junctional femoral hemorrhage.

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.

Physiologic tolerance of descending thoracic aortic balloon occlusion in a swine model of hemorrhagic shock

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an emerging technique in trauma; however, the physiologic sequelae have not been well quantified. The objectives of this study were to characterize the burden of reperfusion and organ dysfunction of REBOA incurred during 30 or 90 min of class IV shock in a survivable porcine model of hemorrhage.

METHODS

After induction of shock, animals were randomized into 4 groups (n = 6): 30 min of shock alone (30-Shock) or with REBOA (30-REBOA) and 90 min of shock alone (90-Shock) or with REBOA (90-REBOA). Cardiovascular homeostasis was then restored with blood, fluid, and vasopressors for 48 h. Outcomes included mean central aortic pressure (MCAP), lactate concentration, organ dysfunction, histologic evaluation, and resuscitation requirements.

RESULTS

Both REBOA groups had greater MCAPs throughout their shock phase compared to controls (P < .05) but accumulated a significantly greater serum lactate burden, which returned to control levels by 150 min in the 30-REBOA groups and 320 min in the 90-REBOA group. There was a greater level of renal dysfunction and evidence of liver necrosis seen in the 90-REBOA group compared to the 90-Shock group. There was no evidence of cerebral or spinal cord necrosis in any group. The 90-REBOA group required more fluid resuscitation than the 90-Shock group (P = .05).

CONCLUSION

REBOA in shock improves MCAP and is associated with a greater lactate burden; however, this lactate burden returned to control levels within the study period. Ultimately, prolonged REBOA is a survivable and potentially life-saving intervention in the setting of hemorrhagic shock and cardiovascular collapse in the pig.