Zsolt T. Stockinger

Prehospital Supplemental Oxygen in Trauma Patients: Its Efficacy and Implications for Military Medical Care

Despite its near-universal use, few data exist to support the efficacy of prehospital supplemental oxygen (PH O2) in trauma patients. Data were reviewed from 5,090 patients not requiring assisted ventilation who were transported to our level I trauma center. Of these, 2,203 (43.3%) received PH O2 and 2,887 (56.7%) did not. Patients who received PH O2 had higher mortality than those without PH O2 (2.3% vs. 1.1%, p = 0.011). When corrected for Injury Severity Score, mechanism of injury, and age, those receiving PH O2 fared worse or no better than those who did not receive it. This suggests that supplemental oxygen does not improve survival in traumatized patients who are not in respiratory distress. This has implications for the management of casualties in combat or austere environments.

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.

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.

Reexamination of a Battlefield Trauma Golden Hour Policy

BACKGROUND Most combat casualties who die, do so in the prehospital setting. Efforts directed toward alleviating prehospital combat trauma death, known as killed in action (KIA) mortality, have the greatest opportunity for eliminating preventable death. METHODS Four thousand five hundred forty-two military casualties injured in Afghanistan from September 11, 2001, to March 31, 2014, were included in this retrospective analysis to evaluate proposed explanations for observed KIA reduction after a mandate by Secretary of Defense Robert M. Gates that transport of injured service members occur within 60 minutes. Using inverse probability weighting to account for selection bias, data were analyzed using multivariable logistic regression and simulation analysis to estimate the effects of (1) gradual improvement, (2) damage control resuscitation, (3) harm from inadequate resources, (4) change in wound pattern, and (5) transport time on KIA mortality. RESULTS The effect of gradual improvement measured as a time trend was not significant (adjusted odds ratio [AOR], 0.99; 95% confidence interval [CI], 0.94-1.03; p = 0.58). For casualties with military Injury Severity Score of 25 or higher, the odds of KIA mortality were 83% lower for casualties who needed and received prehospital blood transfusion (AOR, 0.17; 95% CI, 0.06-0.51; p = 0.002); 33% lower for casualties receiving initial treatment by forward surgical teams (AOR, 0.67; 95% CI, 0.58-0.78; p < 0.001); 70%, 74%, and 87% lower for casualties with dominant injuries to head (AOR, 0.30; 95% CI, 0.23-0.38; p < 0.001), abdomen (AOR, 0.26, 95% CI, 0.19-0.36; p < 0.001) and extremities (AOR, 0.13; 95% CI, 0.09-0.17; p < 0.001); 35% lower for casualties categorized with blunt injuries (AOR, 0.65; 95% CI, 0.46-0.92; p = 0.01); and 39% lower for casualties transported within one hour (AOR, 0.61; 95% CI, 0.51-0.74; p < 0.001). Results of simulations in which transport times had not changed after the mandate indicate that KIA mortality would have been 1.4% higher than observed, equating to 135 more KIA deaths (95% CI, 105-164). CONCLUSION Reduction in KIA mortality is associated with early treatment capabilities, blunt mechanism, select body locations of injury, and rapid transport. LEVEL OF EVIDENCE Therapy, level III.BACKGROUND Most combat casualties who die, do so in the prehospital setting. Efforts directed toward alleviating prehospital combat trauma death, known as killed in action (KIA) mortality, have the greatest opportunity for eliminating preventable death. METHODS Four thousand five hundred forty-two military casualties injured in Afghanistan from September 11, 2001, to March 31, 2014, were included in this retrospective analysis to evaluate proposed explanations for observed KIA reduction after a mandate by Secretary of Defense Robert M. Gates that transport of injured service members occur within 60 minutes. Using inverse probability weighting to account for selection bias, data were analyzed using multivariable logistic regression and simulation analysis to estimate the effects of (1) gradual improvement, (2) damage control resuscitation, (3) harm from inadequate resources, (4) change in wound pattern, and (5) transport time on KIA mortality. RESULTS The effect of gradual improvement measured as a time trend was not significant (adjusted odds ratio [AOR], 0.99; 95% confidence interval [CI], 0.94–1.03; p = 0.58). For casualties with military Injury Severity Score of 25 or higher, the odds of KIA mortality were 83% lower for casualties who needed and received prehospital blood transfusion (AOR, 0.17; 95% CI, 0.06–0.51; p = 0.002); 33% lower for casualties receiving initial treatment by forward surgical teams (AOR, 0.67; 95% CI, 0.58–0.78; p < 0.001); 70%, 74%, and 87% lower for casualties with dominant injuries to head (AOR, 0.30; 95% CI, 0.23–0.38; p < 0.001), abdomen (AOR, 0.26, 95% CI, 0.19–0.36; p < 0.001) and extremities (AOR, 0.13; 95% CI, 0.09–0.17; p < 0.001); 35% lower for casualties categorized with blunt injuries (AOR, 0.65; 95% CI, 0.46–0.92; p = 0.01); and 39% lower for casualties transported within one hour (AOR, 0.61; 95% CI, 0.51–0.74; p < 0.001). Results of simulations in which transport times had not changed after the mandate indicate that KIA mortality would have been 1.4% higher than observed, equating to 135 more KIA deaths (95% CI, 105–164). CONCLUSION Reduction in KIA mortality is associated with early treatment capabilities, blunt mechanism, select body locations of injury, and rapid transport. LEVEL OF EVIDENCE Therapy, level III.

Comparison of Military and Civilian Methods for Determining Potentially Preventable Deaths: A Systematic Review

Importance Military and civilian trauma experts initiated a collaborative effort to develop an integrated learning trauma system to reduce preventable morbidity and mortality. Because the Department of Defense does not currently have recommended guidelines and standard operating procedures to perform military preventable death reviews in a consistent manner, these performance improvement processes must be developed. Objectives To compare military and civilian preventable death determination methods to understand the existing best practices for evaluating preventable death. Evidence Review This systematic review followed the PRISMA reporting guidelines. English-language articles were searched from inception to February 15, 2017, using the following databases: MEDLINE (Ovid), Evidence-Based Medicine Reviews (Ovid), PubMed, CINAHL, and Google Scholar. Articles were initially screened for eligibility and excluded based on predetermined criteria. Articles reviewing only prehospital deaths, only inhospital deaths, or both were eligible for inclusion. Information on study characteristics was independently abstracted by 2 investigators. Reported are methodological factors affecting the reliability of preventable death studies and the preventable death rate, defined as the number of potentially preventable deaths divided by the total number of deaths within a specific patient population. Findings Fifty studies (8 military and 42 civilian) met the inclusion criteria. In total, 1598 of 6500 military deaths reviewed and 3346 of 19 108 civilian deaths reviewed were classified as potentially preventable. Among military studies, the preventable death rate ranged from 3.1% to 51.4%. Among civilian studies, the preventable death rate ranged from 2.5% to 85.3%. The high level of methodological heterogeneity regarding factors, such as preventable death definitions, review process, and determination criteria, hinders a meaningful quantitative comparison of preventable death rates. Conclusions and Relevance The reliability of military and civilian preventable death studies is hindered by inconsistent definitions, incompatible criteria, and the overall heterogeneity in study methods. The complexity, inconsistency, and unpredictability of combat require unique considerations to perform a methodologically sound combat-related preventable death review. As the Department of Defense begins the process of developing recommended guidelines and standard operating procedures for performing military preventable death reviews, consideration must be given to the factors known to increase the risk of bias and poor reliability.

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.

Assessment of Groin Application of Junctional Tourniquets in a Manikin Model.

UNLABELLED Introduction To aid in preparation of military medic trainers for a possible new curriculum in teaching junctional tourniquet use, the investigators studied the time to control hemorrhage and blood volume lost in order to provide evidence for ease of use. Hypothesis Models of junctional tourniquet could perform differentially by blood loss, time to hemostasis, and user preference. METHODS In a laboratory experiment, 30 users controlled simulated hemorrhage from a manikin (Combat Ready Clamp [CRoC] Trainer) with three iterations each of three junctional tourniquets. There were 270 tests which included hemorrhage control (yes/no), time to hemostasis, and blood volume lost. Users also subjectively ranked tourniquet performance. Models included CRoC, Junctional Emergency Treatment Tool (JETT), and SAM Junctional Tourniquet (SJT). Time to hemostasis and total blood loss were log-transformed and analyzed using a mixed model analysis of variance (ANOVA) with the users represented as random effects and the tourniquet model used as the treatment effect. Preference scores were analyzed with ANOVA, and Tukeys honest significant difference test was used for all post-hoc pairwise comparisons. RESULTS All tourniquet uses were 100% effective for hemorrhage control. For blood loss, CRoC and SJT performed best with least blood loss and were significantly better than JETT; in pairwise comparison, CRoC-JETT (P .5, all models). CONCLUSION The CRoC and SJT performed best in having least blood loss, CRoC performed best in having least time to hemostasis, and users did not differ in preference of model. Models of junctional tourniquet performed differentially by blood loss and time to hemostasis. Kragh JF Jr , Lunati MP , Kharod CU , Cunningham CW , Bailey JA , Stockinger ZT , Cap AP , Chen J , Aden JK 3d , Cancio LC . Assessment of groin application of junctional tourniquets in a manikin model. Prehosp Disaster Med. 2016;31(4):358-363.

Aural Blast Injury/Acoustic Trauma and Hearing Loss

Hearing is a critical sense to military performance. The ability to detect, identify, and localize sounds, the ability to maintain spatial awareness on the battlefield and the awareness to control ones own noise production can be vital to troops stealth, survivability, and lethality. Hazardous noise is an environmental public health threat encountered in training at war, and in many off-duty activities. The risk to hearing and the resultant damage from any of these hazardous exposures is generally invisible, insidious and cumulative. Regardless of the source of injury, hearing loss degrades the sensor that integrates Service Members with their environment, provides for unity of effort, and ensures command and control.Acoustic trauma-induced hear loss and tinnitus are the two most prevalent disabilities in veterans, with over 765,000 cases in the Gulf War era alone. To counter this threat, it is necessary to push for early identification and early intervention through a trusted surveillance system. Success will require advocacy, education, and encouragement of self-reporting for evaluation following symptomatic noise exposures. This Clinical Practice Guideline (CPG) is a step to ensure the hearing health, readiness, protection, and care of Service Members. This will in turn optimize troop performance and minimize injury risk and mishap.

Orthopedic Trauma: Extremity Fractures

Fractures continue to account for a large proportion of combat-related injuries. The basic tenets of irrigation, debridement, soft tissue care, and vigilant monitoring/fasciotomy for acute compartment syndrome persist. Closed management of fractures with splinting or casting is acceptable. If time and facility allow, external fixation of fractures offer many advantages over closed treatment but require knowledge, experience and skill in the safe placement of pins. The care of host nationals presents unique challenges and deployed surgeons must be flexible and resourceful in these situations.