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Article 1
Reassessing the cardiac box: A comprehensive evaluation of the relationship between thoracic gunshot wounds and cardiac injury. Jhunjhunwala R, Mina MJ, Roger EI, Dente CJ, Heninger M, Carr JS, Dougherty SD, Gelbard RB, Nicholas JM, Wyrzykowski AD, Feliciano DV, Morse BC. J Trauma Acute Care Surg. 2017 Sep;83(3):349-355.
A consistent and persistent teaching among surgeons has been the utility of using the borders of the “cardiac box” to delineate the area of the chest where penetrating trauma is likely to result in a cardiac injury. The teaching is ostensibly anatomically sensible and physiologically important – early diagnosis and intervention is paramount to survival in these injuries, but is it really accurate? Jhunjhunwala and his colleagues conducted a retrospective, population-based review of an autopsy registry and included all patients who suffered torso gunshot injuries from January 2011 to December 2013. The anterior, posterior, and lateral chest wall was stratified into “regions”. Ultimately, 263 patients with 320 GSWs were reviewed. Of these, 31% of GSWs that hit the cardiac box caused a cardiac injury, while 21% of GSWs outside the box did – the difference was not statistically significant (p=0.09). This lack of statistical significance was maintained when the “gold standard cardiac box” was compared to other combinations of regions as well.
In fact, it was noted that the highest relative risk for cardiac injury occurred when the GSW penetrated between the left anterior and left posterior axillary lines (RR: 1.33, 41% of GSWs resulted in a cardiac injury). This is, in fact, intuitive as the proximity to the apex of the heart is maintained. Conversely, areas of the right thorax (that are currently part of the cardiac box) had relatively low rates of cardiac injury. Ultimately, this study predicted that the region of the chest wall from the anterior to the posterior midline of the left thorax had the highest discriminatory value in predicting cardiac injuries. This study is limited by the fact that it is an autopsy review. Theoretically, there may be some variation in the pattern of GSW trauma in patients who survived and had a cardiac injury. This study would not account for that. Nevertheless, the lesson of this report with respect to emphasizing a high index of suspicion for cardiac injury after torso GSWs prefacing early sonographic assessments for hemopericardium, should be taken to heart – pun intended.
Article 2
Increased mortality in trauma patients who develop postintubation hypotension. Green RS, Butler MB, Erdogan M. J Trauma Acute Care Surg. 2017 Oct;83(4):569-574.
It is not surprising that trauma will result in situations where securing a patient’s airway becomes paramount. Depending on what co-existent injuries may be present, these patients may be unstable – induction for endotracheal intubation may result in significant adverse events including postintubation hypotension (PIH). This scenario has already been shown to increase rates of complications and mortality in ICU and ED patients but this is the first study to look exclusively at its effects on trauma patients. Green and his colleagues conducted a retrospective review to evaluate whether PIH independently contributed to mortality among trauma patients. They queried the Nova Scotia Trauma Registry (a population-based registry) for adult trauma patients through blinded abstractors. Amongst several other demographic data points, they collected specific peri-intubation data including vitals, intravenous volume delivered, GCS, temperature, amongst others. PIH was defined as any increase in titration of vasopressor medication, any decrease in SBP by 20% or more (or a decrease of 5 mm Hg if the patient was already hypotensive), or a an absolute systolic blood pressure of ≤ 80, or mean arterial pressure of ≤ 60.
Ultimately, 444 trauma patients were analyzed with a prevalence of PIH of 36.3%. Expectedly, patients who suffered PIH were more likely to be more severely injured and older. There was no difference in other demographics, rates of TBI, and volume of fluid administered within 15 minutes of intubation. Nevertheless, ED and inpatient mortality was significantly higher among patients who developed PIH. As a retrospective review, there are inherent limitations. Patients who develop PIH may be more predisposed to die irrespective of whether they develop PIH or not. Moreover, without a validated protocol, variations in practice and decision-making related to intubating an individual patient can confound the results. Further, although practical, the use of a blood pressure reading is not the most nuanced measure of peripheral perfusion. To the group’s credit they understand and reference this limitation and opted for practicality in conducting their database review. This study underscores the physiologic fragility of trauma patients, especially as the average age of a trauma patient continues to rise. It would behoove the trauma practitioner to anticipate any physiologic insults and be prepared to react to them.
Article 3
Military use of tranexamic acid in combat trauma: Does it Matter? Howard JT, Stockinger ZT, Cap AP, Bailey JA, Gross KR. J Trauma Acute Care Surg. 2017 Oct 83;4: 579-588.
Tranexamic acid (TXA) has been previously reported to have a mortality benefit in civilian and combat-related trauma but with some inconsistency in findings. The recent EAST Practice Management Guidelines on Damage Control Resuscitation published in the Journal of Trauma in January, 2017, gave a conditional recommendation for the in-hospital use of TXA as a hemostatic agent in the management of the severely injured adult trauma patient. TXA use has also been added to the Joint Theater Trauma System Damage Control Resuscitation Clinical Practice Guidelines but its use has been closely monitored. The authors of this study set out to estimate the mortality benefit and potential risk of VTE associated with the use of TXA in the military trauma combat setting using a larger sample and more robust statistical methods to inform continued guidance on the use of TXA in the military. This was a retrospective review of data compiled from the DoD Trauma registry that included US Military, NATO military, host military/police and local civilian patients injured in combat in Afghanistan from October 2010 through March 2014. Outcomes included all-cause mortality and the occurrence of PE or DVT. Inclusion criteria were those patients injured in combat in Afghanistan, admitted to a role 3 MTF and who received at least 1 unit of blood.
A total of 3,773 patients met criteria for inclusion. Patients were divided into those that received TXA and those who did not. A subset analysis was performed on patients requiring massive transfusion (N=784), a propensity score-matched sample (N=1030) as well as US/NATO military (N=1262). Data analysis consisted of both unadjusted bivariate and covariate-adjusted, multivariable comparisons of mortality, PE and DVT outcomes. There was no statistically significant mortality benefit associated with the use of TXA except in a small subset of individuals with multiple amputation injuries (N=140) where mortality at each time point (24hrs, 48hrs and 30 days) was significantly lower for the TXA group compared with the no TXA group. TXA was significantly associated with an increase in PE risk in the total, MT and US/NATO samples (182% (HR, 2.82; 95% CI, 2.08-3.81; p <0.001), 264% (HR, 3.64; 95% CI, 1.96-6.78; p = 0.003), and 155% (HR, 2.55; 95% CI 1.73-3.69; p = 0.002). In the propensity matched sample, however, TXA use was associated with an estimated 236% (HR, 3.36; 95% CI 0.80-14.10; p = 0.10) increase in PE but the lower 95% CI bound of 0.80 overlapped with the upper non-inferiority margin of 1.25. Results of the DVT analyses were similar.
This is the largest, most comprehensive study of TXA use in a combat trauma population to date but was not sufficiently powered to detect the observed mortality association as statistically significant. Their findings do suggest that the use of TXA in combat trauma may be associated with an increased risk of PE and DVT. TXA use will continue to be closely monitored and scrutinized in the military trauma patient particularly in regards to the development and prevention of VTE.
Article 4
Rotational thromboelastometry significantly optimizes transfusion practices for damage control resuscitation in combat casualties. Prat NJ, Meyer AD, Ingalls NK, Trichereau J, DuBose JJ, Cap AP. J Trauma Acute Care Surg. 2017 Sept;83(3): 373-380.
The purpose of this paper was to evaluate the before and after effects of implementing ROTEM, a rapid-diagnostic point-of-care coagulation device, on the DCR practices in the combat support hospital at Bagram Air Base, Afghanistan. The hypothesis was that ROTEM use in a military setting would recognize early coagulopathy of trauma in critically wounded soldiers, thus leading to customized therapy that would diverge from empiric 1:1:1:1-based transfusion. This was a retrospective study using data that was collected from the DoD Trauma registry on transfusions before (pre-ROTEM) and after (post-ROTEM) implementation. Subjects who were transfused with at least one unit of blood product for three months preceding ROTEM implementation were compared to post-ROTEM. The patient population included civilians and both US and foreign military personnel. Additional data included the total amount of crystalloid and blood products (RBC, FFP, CRYO, recombinant FVIIa, apheresis PLT and fresh whole blood) administered within 24hrs from admission. Reported outcomes were the proportion of patients receiving a blood transfusion, total units transfused, and the ratios of products FFP: RBC, PLT: RBC, and CRYO:RBC. Treating physicians had access to the ROTEM results but no standard protocol to guide transfusions.
Between August 2011 and January 2012, 970 trauma patients were admitted to the Craig Theater Hospital, BAF in Afghanistan. Of these, 134 (21%) patients received a blood transfusion in the pre-ROTEM period (August 2011 to October 2011) and 85 (26%) patients in the post-ROTEM period (November 2011 to January 2012). The number of massive transfusions was similar between the pre- and post-ROTEM at 5% and 6% respectively (p =0.55). Before the introduction of ROTEM to DCR at BAF, the overall blood product transfusion volume was 9.9 units/day compared with 12.7 units/day in the post-ROTEM period. There was no significant change in overall mortality between groups. After the introduction of ROTEM analysis, physicians transfused 4x the PLTS and 2x CRYO, which was much closer to achieving the 1:1:1:1 prescription of DCR. There was no significant change in FFP:pRBC ratio between groups (p =0.20). The post-ROTEM group received significantly more fluid resuscitation compared with the pre-ROTEM group (P = 0.0001).
The use of ROTEM measurements in this 6-month before and after study of a combat support hospital prompted the trauma team to significantly increase the amounts of CRYO and PLT transfused. This is the first study to document that the deployment of a ROTEM unit in a combat support hospital can improve the coagulation management of critical combat casualties to provide a more hemostatic resuscitation.
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