Kirby R. Gross

The Effect of a Golden Hour Policy on the Morbidity and Mortality of Combat Casualties

IMPORTANCE The term golden hour was coined to encourage urgency of trauma care. In 2009, Secretary of Defense Robert M. Gates mandated prehospital helicopter transport of critically injured combat casualties in 60 minutes or less. OBJECTIVES To compare morbidity and mortality outcomes for casualties before vs after the mandate and for those who underwent prehospital helicopter transport in 60 minutes or less vs more than 60 minutes. DESIGN, SETTING, AND PARTICIPANTS A retrospective descriptive analysis of battlefield data examined 21,089 US military casualties that occurred during the Afghanistan conflict from September 11, 2001, to March 31, 2014. Analysis was conducted from September 1, 2014, to January 21, 2015. MAIN OUTCOMES AND MEASURES Data for all casualties were analyzed according to whether they occurred before or after the mandate. Detailed data for those who underwent prehospital helicopter transport were analyzed according to whether they occurred before or after the mandate and whether they occurred in 60 minutes or less vs more than 60 minutes. Casualties with minor wounds were excluded. Mortality and morbidity outcomes and treatment capability-related variables were compared. RESULTS For the total casualty population, the percentage killed in action (16.0% [386 of 2411] vs 9.9% [964 of 9755]; P < .001) and the case fatality rate ([CFR] 13.7 [469 of 3429] vs 7.6 [1344 of 17,660]; P < .001) were higher before vs after the mandate, while the percentage died of wounds (4.1% [83 of 2025] vs 4.3% [380 of 8791]; P = .71) remained unchanged. Decline in CFR after the mandate was associated with an increasing percentage of casualties transported in 60 minutes or less (regression coefficient, -0.141; P < .001), with projected vs actual CFR equating to 359 lives saved. Among 4542 casualties (mean injury severity score, 17.3; mortality, 10.1% [457 of 4542]) with detailed data, there was a decrease in median transport time after the mandate (90 min vs 43 min; P < .001) and an increase in missions achieving prehospital helicopter transport in 60 minutes or less (24.8% [181 of 731] vs 75.2% [2867 of 3811]; P < .001). When adjusted for injury severity score and time period, the percentage killed in action was lower for those critically injured who received a blood transfusion (6.8% [40 of 589] vs 51.0% [249 of 488]; P < .001) and were transported in 60 minutes or less (25.7% [205 of 799] vs 30.2% [84 of 278]; P < .01), while the percentage died of wounds was lower among those critically injured initially treated by combat support hospitals (9.1% [48 of 530] vs 15.7% [86 of 547]; P < .01). Acute morbidity was higher among those critically injured who were transported in 60 minutes or less (36.9% [295 of 799] vs 27.3% [76 of 278]; P < .01), those severely and critically injured initially treated at combat support hospitals (severely injured, 51.1% [161 of 315] vs 33.1% [104 of 314]; P < .001; and critically injured, 39.8% [211 of 530] vs 29.3% [160 of 547]; P < .001), and casualties who received a blood transfusion (50.2% [618 of 1231] vs 3.7% [121 of 3311]; P < .001), emphasizing the need for timely advanced treatment. CONCLUSIONS AND RELEVANCE A mandate made in 2009 by Secretary of Defense Gates reduced the time between combat injury and receiving definitive care. Prehospital transport time and treatment capability are important factors for casualty survival on the battlefield.

Association of Prehospital Blood Product Transfusion During Medical Evacuation of Combat Casualties in Afghanistan With Acute and 30-Day Survival

Importance Prehospital blood product transfusion in trauma care remains controversial due to poor-quality evidence and cost. Sequential expansion of blood transfusion capability after 2012 to deployed military medical evacuation (MEDEVAC) units enabled a concurrent cohort study to focus on the timing as well as the location of the initial transfusion. Objective To examine the association of prehospital transfusion and time to initial transfusion with injury survival. Design, Setting, and Participants Retrospective cohort study of US military combat casualties in Afghanistan between April 1, 2012, and August 7, 2015. Eligible patients were rescued alive by MEDEVAC from point of injury with either (1) a traumatic limb amputation at or above the knee or elbow or (2) shock defined as a systolic blood pressure of less than 90 mm Hg or a heart rate greater than 120 beats per minute. Exposures Initiation of prehospital transfusion and time from MEDEVAC rescue to first transfusion, regardless of location (ie, prior to or during hospitalization). Transfusion recipients were compared with nonrecipients (unexposed) for whom transfusion was delayed or not given. Main Outcomes and Measures Mortality at 24 hours and 30 days after MEDEVAC rescue were coprimary outcomes. To balance injury severity, nonrecipients of prehospital transfusion were frequency matched to recipients by mechanism of injury, prehospital shock, severity of limb amputation, head injury, and torso hemorrhage. Cox regression was stratified by matched groups and also adjusted for age, injury year, transport team, tourniquet use, and time to MEDEVAC rescue. Results Of 502 patients (median age, 25 years [interquartile range, 22 to 29 years]; 98% male), 3 of 55 prehospital transfusion recipients (5%) and 85 of 447 nonrecipients (19%) died within 24 hours of MEDEVAC rescue (between-group difference, −14% [95% CI, −21% to −6%]; P = .01). By day 30, 6 recipients (11%) and 102 nonrecipients (23%) died (between-group difference, −12% [95% CI, −21% to −2%]; P = .04). For the 386 patients without missing covariate data among the 400 patients within the matched groups, the adjusted hazard ratio for mortality associated with prehospital transfusion was 0.26 (95% CI, 0.08 to 0.84, P = .02) over 24 hours (3 deaths among 54 recipients vs 67 deaths among 332 matched nonrecipients) and 0.39 (95% CI, 0.16 to 0.92, P = .03) over 30 days (6 vs 76 deaths, respectively). Time to initial transfusion, regardless of location (prehospital or during hospitalization), was associated with reduced 24-hour mortality only up to 15 minutes after MEDEVAC rescue (median, 36 minutes after injury; adjusted hazard ratio, 0.17 [95% CI, 0.04 to 0.73], P = .02; there were 2 deaths among 62 recipients vs 68 deaths among 324 delayed transfusion recipients or nonrecipients). Conclusions and Relevance Among medically evacuated US military combat causalities in Afghanistan, blood product transfusion prehospital or within minutes of injury was associated with greater 24-hour and 30-day survival than delayed transfusion or no transfusion. The findings support prehospital transfusion in this setting.

Prehospital Pain Medication Use by U.S. Forces in Afghanistan

We report the results of a process improvement initiative to examine the current use and safety of prehospital pain medications by U.S. Forces in Afghanistan. Prehospital pain medication data were prospectively collected on 309 casualties evacuated from point of injury (POI) to surgical hospitals from October 2012 to March 2013. Vital signs obtained from POI and flight medics and on arrival to surgical hospitals were compared using one-way analysis of variance test. 119 casualties (39%) received pain medication during POI care and 283 (92%) received pain medication during tactical evacuation (TACEVAC). Morphine and oral transmucosal fentanyl citrate were the most commonly used pain medications during POI care, whereas ketamine and fentanyl predominated during TACEVAC. Ketamine was associated with increase in systolic blood pressure compared to morphine (+7 ± 17 versus -3 ± 14 mm Hg, p = 0.04). There was no difference in vital signs on arrival to the hospital between casualties who received no pain medication, morphine, fentanyl, or ketamine during TACEVAC. In this convenience sample, fentanyl and ketamine were as safe as morphine for prehospital use within the dose ranges administered. Future efforts to improve battlefield pain control should focus on improved delivery of pain control at POI and the role of combination therapies.

The military injury severity score (mISS): A better predictor of combat-mortality than injury severity score (ISS)

BACKGROUND The Military Injury Severity Score (mISS) was developed to better predict mortality in complex combat injuries but has yet to be validated. METHODS US combat trauma data from Afghanistan and Iraq from January 1, 2003, to December 31, 2014, from the US Department of Defense Trauma Registry (DoDTR) were analyzed. Military ISS, a variation of the ISS, was calculated and compared with standard ISS scores. Receiver operating characteristic curve, area under the curve, and Hosmer-Lemeshow statistics were used to discriminate and calibrate between mISS and ISS. Wilcoxon-Mann-Whitney, t test and &khgr;2 tests were used, and sensitivity and specificity calculated. Logistic regression was used to calculate the likelihood of mortality associated with levels of mISS and ISS overall. RESULTS Thirty thousand three hundred sixty-four patients were analyzed. Most were male (96.8%). Median age was 24 years (interquartile range [IQR], 21–29 years). Battle injuries comprised 65.3%. Penetrating (39.5%) and blunt (54.2%) injury types and explosion (51%) and gunshot wound (15%) mechanisms predominated. Overall mortality was 6.0%. Median mISS and ISS were similar in survivors (5 [IQR, 2–10] vs. 5 [IQR, 2–10]) but different in nonsurvivors, 30 (IQR, 16–75) versus 24 (IQR, 9–23), respectively (p < 0.0001). Military ISS and ISS were discordant in 17.6% (n = 5,352), accounting for 56.2% (n = 1,016) of deaths. Among cases with discordant severity scores, the median difference between mISS and ISS was 9 (IQR, 7–16); range, 1 to 59. Military ISS and ISS shared 78% variability (R2 = 0.78). Area under the curve was higher in mISS than in ISS overall (0.82 vs. 0.79), for battle injury (0.79 vs. 0.76), non–battle injury (0.87 vs. 0.86), penetrating (0.81 vs. 0.77), blunt (0.77 vs. 0.75), explosion (0.81 vs. 0.78), and gunshot (0.79 vs. 0.73), all p < 0.0001. Higher mISS and ISS were associated with higher mortality. Compared with ISS, mISS had higher sensitivity (81.2 vs. 63.9) and slightly lower specificity (80.2 vs. 85.7). CONCLUSION Military ISS predicts combat mortality better than does ISS. LEVEL OF EVIDENCE Prognostic and epidemiologic study, level III.

Evaluation of role 2 (R2) medical resources in the Afghanistan combat theater: Initial review of the joint trauma system R2 registry.

BACKGROUND A Role 2 registry (R2R) was developed in 2008 by the US Joint Trauma System (JTS). The purpose of this project was to undertake a preliminary review of the R2R to understand combat trauma epidemiology and related interventions at these facilities to guide training and optimal use of forward surgical capability in the future. METHODS A retrospective review of available JTS R2R records; the registry is a convenience sample entered voluntarily by members of the R2 units. Patients were classified according to basic demographics, affiliation, region where treatment was provided, mechanism of injury, type of injury, time and method of transport from point of injury (POI) to R2 facility, interventions at R2, and survival. Analysis included trauma patients aged ≥18 years or older wounded in year 2008 to 2014, and treated in Afghanistan. RESULTS A total of 15,404 patients wounded and treated in R2 were included in the R2R from February 2008 to September 2014; 12,849 patients met inclusion criteria. The predominant patient affiliations included US Forces, 4,676 (36.4%); Afghan Forces, 4,549 (35.4%); and Afghan civilians, 2,178 (17.0%). Overall, battle injuries predominated (9,792 [76.2%]). Type of injury included penetrating, 7,665 (59.7%); blunt, 4,026 (31.3%); and other, 633 (4.9%). Primary mechanism of injury included explosion, 5,320 (41.4%); gunshot wounds, 3,082 (24.0%); and crash, 1,209 (9.4%). Of 12,849 patients who arrived at R2, 167 (1.3%) were dead; of 12,682 patients who were alive upon arrival, 342 (2.7%) died at R2. CONCLUSION This evaluation of the R2R describes the patient profiles of and common injuries treated in a sample of R2 facilities in Afghanistan. Ongoing and detailed analysis of R2R information may provide evidence-based guidance to military planners and medical leaders to best prepare teams and allocate R2 resources in future operations. Given the limitations of the data set, conclusions must be interpreted in context of other available data and analyses, not in isolation. LEVEL OF EVIDENCE Epidemiologic study, level IV.

Laboratory Assessment of Out-of-hospital Interventions to Control Junctional Bleeding from the Groin in a Manikin Model

Abstract : Junctional body regions between the trunk and its appendages, such as the groin, are too proximal for a regular limb tourniquet to fit [1,2]. Not since 1993 s Black Hawk Down has junctional hemorrhage control become such a hot topic in military casualty care [1 7]. In February 2013, the US military s Task Force Medical Afghanistan requested a fill of a gap in junctional hemorrhage control as an urgent operational need, meaning that junctional hemorrhage control devices should be considered urgently to fill a gap in medical care in war. A small but growing body of evidence indicates that hemorrhage control can be attained out-of-hospital with mechanical compression, using such interventions as medical devices, on a pressure point proximal to a bleeding wound [3 9]. To evaluate laboratory use of junctional hemorrhage control interventions, wegathered data on stopping groin bleeding in a manikin model to understand the plausibility of such interventions for future human subject research. Under an approved protocol, we tested efficacy of interventions in a manikin designed to trainmedics in out-of-hospital hemorrhage control (Combat Ready Clamp [CRoC] Trainer Manikin, Operative Experience, Inc, North East,MD).We filled the blood reservoirwith 4 liters ofwater; we refilled the reservoir after 5 iterations or 1.5 liters of lost fluid, whichever came first. The manikin had a right-groin gunshot wound through the proximal thighwhere the common femoral artery flow was controllable by skin compression over it at the level of the inguinal fold. There was 3 cm between the pressure point where compression was applied and the proximal extent of the wound. Interventions were timed, blood loss was measured, and efficacy was noted. Efficacy was operationally defined as visually stopped flow into the wound fromthe vessel lumen.

Analysis of injury patterns and roles of care in US and Israel militaries during recent conflicts: Two are better than one.

BACKGROUND As new conflicts emerge and enemies evolve, military medical organizations worldwide must adopt the “lessons learned.” In this study, we describe roles of care (ROCs) deployed and injuries sustained by both US and Israeli militaries during recent conflicts. The purpose of this collaborative work is facilitate exchange of medical data among allied forces in order to advance military medicine and facilitate strategic readiness for future military engagements that may involve less predictable situations of evacuation and care, such as prolonged field care. METHODS This retrospective study was conducted for the periods of 2003 to 2014 from data retrieved from the Department of Defense Trauma Registry and the Israel Defense Force (IDF) Trauma Registry. Comparative analyses included ROC capabilities, casualties who died of wounds, as well as mechanism of injury, anatomical wound distribution, and Injury Severity Score of US and IDF casualties during recent conflicts. RESULTS Although concept of ROCs was similar among militaries, the IDF supports increased capabilities at point of injury and Role 1 including the presence of physicians, but with limited deployment of other ROCs; conversely, the US maintains fewer capabilities at Role 1 but utilized the entire spectrum of care, including extensive deployment of Roles 2/2+, during recent conflicts. Casualties from US forces (n = 19,005) and IDF (n = 2,637) exhibited significant differences in patterns of injury with higher proportions of casualties who died of wounds in the US forces (4%) compared with the IDF (0.6%). CONCLUSIONS As these data suggest deployed ROCs and injury patterns of US and Israeli militaries were both conflict and system specific. We envision that identification of discordant factors and common medical strategies of the two militaries will enable strategic readiness for future conflicts as well as foster further collaboration among allied forces with the overarching universal goal of eliminating preventable death on the battlefield.

Military use of tranexamic acid in combat trauma: Does it matter?

BACKGROUND Tranexamic acid (TXA) has been previously reported to have a mortality benefit in civilian and combat-related trauma, and was thus added to the Joint Theater Trauma System Damage Control Resuscitation Clinical Practice Guideline. As part of ongoing system-wide performance improvement, the use of TXA has been closely monitored. The goal was to evaluate the efficacy and safety of TXA use in military casualties and provide additional guidance for continued use. METHODS A total of 3,773 casualties were included in this retrospective, observational study of data gathered from a trauma registry. The total sample, along with 3 sub-samples for massive transfusion patients (n=784), propensity-matched sample (n=1,030) and US/NATO military (n=1,262), were assessed for administration of TXA and time from injury to administration of TXA. Outcomes included mortality and occurrence of pulmonary embolism (PE) and deep vein thrombosis (DVT). Multivariable proportional hazards regression models with robust standard error estimates were used to estimate hazard ratios (HR) for assessment of outcomes while controlling for covariates. RESULTS Results of univariate and multivariate analyses of the total sample (HR=0.97; 95%CI 0.62-1.53; p=0.86); massive transfusion sample (HR=0.84; 95%CI 0.46-1.56; p=0.51); propensity-matched sample (HR=0.68; 95%CI 0.27-1.73; p=0.34); and US/NATO military sample (HR=0.76; 95%CI 0.30-1.92; p=0.48) indicate no statistically significant association between TXA use and mortality. Use of TXA was associated with increased risk of PE in the total sample (HR=2.82; 95%CI 2.08-3.81; p<0.001); massive transfusion sample (HR=3.64; 95%CI 1.96-6.78; p=0.003); US/NATO military sample (HR=2.55; 95%CI 1.73-3.69; p=0.002); but not the propensity-matched sample (HR=3.36; 95%CI 0.80-14.10; p=0.10). TXA was also associated with increased risk of DVT in the total sample (HR=2.00; 95%CI 1.21-3.30; p=0.02) and US/NATO military sample (HR=2.18; 95%CI 1.20-3.96; p=0.02). CONCLUSIONS In the largest study on TXA use in a combat trauma population, TXA was not significantly associated with mortality, due to lack of statistical power. However, our HR estimates for mortality among patients who received TXA are consistent with previous findings from the CRASH2 trial. At the same time, continued scrutiny and surveillance of TXA use in military trauma, specifically for prevention of thromboembolic events, is warranted. LEVEL OF EVIDENCE Retrospective/Case-Control, Therapy Level IV.BACKGROUND Tranexamic acid (TXA) has been previously reported to have a mortality benefit in civilian and combat-related trauma, and was thus added to the Joint Theater Trauma System Damage Control Resuscitation Clinical Practice Guideline. As part of ongoing system-wide performance improvement, the use of TXA has been closely monitored. The goal was to evaluate the efficacy and safety of TXA use in military casualties and provide additional guidance for continued use. METHODS A total of 3,773 casualties were included in this retrospective, observational study of data gathered from a trauma registry. The total sample, along with three subsamples for massive transfusion patients (n = 784), propensity-matched sample (n = 1,030), and US/North Atlantic Treaty Organization (NATO) military (n = 1,262), was assessed for administration of TXA and time from injury to administration of TXA. Outcomes included mortality and occurrence of pulmonary embolism and deep vein thrombosis. Multivariable proportional hazards regression models with robust standard error estimates were used to estimate hazard ratios (HR) for assessment of outcomes while controlling for covariates. RESULTS Results of univariate and multivariate analyses of the total sample (HR, 0.97; 95% confidence interval [CI], 0.62–1.53; p = 0.86), massive transfusion sample (HR, 0.84; 95% CI, 0.46–1.56; p = 0.51), propensity-matched sample (HR, 0.68; 95% CI, 0.27–1.73; p = 0.34), and US/NATO military sample (HR, 0.76; 95% CI, 0.30–1.92; p = 0.48) indicate no statistically significant association between TXA use and mortality. Use of TXA was associated with increased risk of pulmonary embolism in the total sample (HR, 2.82; 95% CI, 2.08–3.81; p < 0.001), massive transfusion sample (HR, 3.64; 95% CI, 1.96–6.78; p = 0.003), US/NATO military sample (HR, 2.55; 95% CI, 1.73–3.69; p = 0.002), but not the propensity-matched sample (HR, 3.36; 95% CI, 0.80–14.10; p = 0.10). TXA was also associated with increased risk of deep vein thrombosis in the total sample (HR, 2.00; 95% CI, 1.21–3.30; p = 0.02) and US/NATO military sample (HR, 2.18; 95% CI, 1.20–3.96; p = 0.02). CONCLUSION In the largest study on TXA use in a combat trauma population, TXA was not significantly associated with mortality, due to lack of statistical power. However, our HR estimates for mortality among patients who received TXA are consistent with previous findings from the CRASH-2 trial. At the same time, continued scrutiny and surveillance of TXA use in military trauma, specifically for prevention of thromboembolic events, is warranted. Level of Evidence Therapeutic, level IV.

The use of rigid eye shields (Fox shields) at the point of injury for ocular trauma in Afghanistan

BACKGROUND Unlike hemorrhagic injuries in which direct pressure is indicated, any pressure placed on the eye after penetrating trauma can significantly worsen the injury by expulsing intraocular contents. The accepted first response measure for obvious or suspected penetrating ocular injury is placement of a rigid shield that vaults the eye so as to prevent accidental iatrogenic aggravation during transport to the ophthalmologist. Patching and placing intervening gauze between the shield and the eye are both contraindicated. Anecdotally, compliance with these recommendations is poor in the military and civilian communities alike; however, published studies documenting compliance are uniformly lacking. This study was undertaken to provide such an evaluation. METHODS In this retrospective observational study, the Department of Defense Trauma Registry was reviewed to identify eye injuries in Afghanistan from 2010 to 2012 and to examine compliance with eye shield recommendations. One hundred fifty-seven records of eye casualties were identified and categorized according to diagnostic codes, noting use of a shield. A subset of 30 records was further analyzed for compliance with other core treatment measures specified by the operant Clinical Practice Guideline. Because comparative studies do not exist, simple statistical analysis was performed. RESULTS Overall, 39% of eye injuries received a shield at the point of injury (61% failure), ranging from 0% to 50% between diagnostic subgroups. Subset analysis revealed that only 4.2% of injuries were successfully mitigated at the point of injury (95.8% failure). CONCLUSION In one of the few studies documenting the use of eye shields after ocular trauma, anecdotal reports of poor, inadequate, or incorrect compliance with basic recommendations were substantiated. Several factors may account for these findings. Corrective efforts should include enhanced educational emphasis and increased shield availability. LEVEL OF EVIDENCE Epidemiologic study, level IV. Therapeutic study, level IV.

A 12-Year Analysis of Nonbattle Injury Among US Service Members Deployed to Iraq and Afghanistan

Importance Nonbattle injury (NBI) among deployed US service members increases the burden on medical systems and results in high rates of attrition, affecting the available force. The possible causes and trends of NBI in the Iraq and Afghanistan wars have, to date, not been comprehensively described. Objectives To describe NBI among service members deployed to Iraq and Afghanistan, quantify absolute numbers of NBIs and proportion of NBIs within the Department of Defense Trauma Registry, and document the characteristics of this injury category. Design, Setting, and Participants In this retrospective cohort study, data from the Department of Defense Trauma Registry on 29 958 service members injured in Iraq and Afghanistan from January 1, 2003, through December 31, 2014, were obtained. Injury incidence, patterns, and severity were characterized by battle injury and NBI. Trends in NBI were modeled using time series analysis with autoregressive integrated moving average and the weighted moving average method. Statistical analysis was performed from January 1, 2003, to December 31, 2014. Main Outcomes and Measures Primary outcomes were proportion of NBIs and the changes in NBI over time. Results Among 29 958 casualties (battle injury and NBI) analyzed, 29 003 were in men and 955 were in women; the median age at injury was 24 years (interquartile range, 21-29 years). Nonbattle injury caused 34.1% of total casualties (n = 10 203) and 11.5% of all deaths (206 of 1788). Rates of NBI were higher among women than among men (63.2% [604 of 955] vs 33.1% [9599 of 29 003]; P < .001) and in Operation New Dawn (71.0% [298 of 420]) and Operation Iraqi Freedom (36.3% [6655 of 18 334]) compared with Operation Enduring Freedom (29.0% [3250 of 11 204]) (P < .001). A higher proportion of NBIs occurred in members of the Air Force (66.3% [539 of 810]) and Navy (48.3% [394 of 815]) than in members of the Army (34.7% [7680 of 22 154]) and Marine Corps (25.7% [1584 of 6169]) (P < .001). Leading mechanisms of NBI included falls (2178 [21.3%]), motor vehicle crashes (1921 [18.8%]), machinery or equipment accidents (1283 [12.6%]), blunt objects (1107 [10.8%]), gunshot wounds (728 [7.1%]), and sports (697 [6.8%]), causing predominantly blunt trauma (7080 [69.4%]). The trend in proportion of NBIs did not decrease over time, remaining at approximately 35% (by weighted moving average) after 2006 and approximately 39% by autoregressive integrated moving average. Assuming stable battlefield conditions, the autoregressive integrated moving average model estimated that the proportion of NBIs from 2015 to 2022 would be approximately 41.0% (95% CI, 37.8%-44.3%). Conclusions and Relevance In this study, approximately one-third of injuries during the Iraq and Afghanistan wars resulted from NBI, and the proportion of NBIs was steady for 12 years. Understanding the possible causes of NBI during military operations may be useful to target protective measures and safety interventions, thereby conserving fighting strength on the battlefield.