Can Thrombelastography Predict Venous Thromboembolic Events in Patients With Severe Extremity Trauma?

OBJECTIVES: An elevated maximal amplitude (mA) value with rapid thrombelastography on admission can identify general trauma patients with an increased risk of venous thromboembolic events (VTEs). We hypothesized that (1) the risk of VTE traditionally assigned to injury lies specifically in those who sustain major orthopaedic trauma and (2) an elevated admission mA value could be used to identify patients with major orthopaedic injuries at risk for VTE during initial hospital admission. DESIGN: Retrospective. SETTING: University level 1 trauma center. PATIENTS/PARTICIPANTS: Consecutive trauma patients admitted to an urban level 1 trauma center between September 2009 and February 2011 who met the criteria for level 1 trauma activation and who were between 18 and 85 years of age were included in our study group. Two groups were created, one whose extremity abbreviated injury severity score was 2 or greater (ORTHO) and the other whose extremity abbreviated injury severity score was <2 (non-ORTHO). MAIN OUTCOME MEASUREMENTS: Pulmonary emboli were confirmed by computed tomography angiography, and deep vein thromboses were confirmed by venous duplex. Univariate analyses were conducted and followed by purposeful regression analysis. RESULTS: Of note, 1818 patients met the inclusion criteria (310 ORTHO and 1508 non-ORTHO). Despite more hypocoagulable r-TEG values on arrival (alpha angle 71 vs. 73 and mA 62 vs. 64, both P < 0.05), ORTHO patients had higher rates of VTE (6.5% vs. 2.7%, P < 0.001). Stepwise regression generated 4 values to predict development of VTE (age, male gender, white race, and ORTHO). After controlling for these variables, admission mA values ≥65 (odds ratio 3.66) and ≥72 (odds ratio 6.70) were independent predictors of VTEs during hospitalization. CONCLUSIONS: Admission rapid thrombelastography mA values can identify patients with major orthopaedic trauma injuries who present with an increased risk of in-hospital deep vein thromboses and pulmonary embolism with a 3.6-fold and 6.7-fold increased risk for mA values ≥65 and ≥72, respectively. LEVEL OF EVIDENCE: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Hypercoagulability after energy drink consumption.

BACKGROUND: Energy drink consumption in the United States has more than doubled over the last decade and has been implicated in cardiac arrhythmias, myocardial infarction, and even sudden cardiac death. We hypothesized that energy drink consumption may increase the risk of adverse cardiovascular events by increasing platelet aggregation, thereby resulting in a relatively hypercoagulable state and increased risk of thrombosis. METHODS: Thirty-two healthy volunteers aged 18-40 y were given 16 oz of bottled water or a standardized, sugar-free energy drink on two separate occasions, 1-wk apart. Beverages were consumed after an overnight fast over a 30-min period. Coagulation parameters and platelet function were measured before and 60 min after consumption using thrombelastography and impedance aggregometry. RESULTS: No statistically significant differences in coagulation were detected using kaolin or rapid thrombelastography. In addition, no differences in platelet aggregation were detected using ristocetin, collagen, thrombin receptor-activating peptide, or adenosine diphosphate-induced multiple impedance aggregometry. However, compared to water controls, energy drink consumption resulted in a significant increase in platelet aggregation via arachidonic acid-induced activation (area under the aggregation curve, 72.4 U versus 66.3 U; P = 0.018). CONCLUSIONS: Energy drinks are associated with increased platelet activity via arachidonic acid-induced platelet aggregation within 1 h of consumption. Although larger clinical studies are needed to further address the safety and health concerns of these drinks, the increased platelet response may provide a mechanism by which energy drinks increase the risk of adverse cardiovascular events.

Admission rapid thrombelastography delivers real-time "actionable" data in pediatric trauma.

PURPOSE: Admission rapid thrombelastography (rTEG) is a "real-time" clinical tool used to evaluate trauma-induced coagulopathy and direct hemostatic resuscitation. The relationship of rTEG to conventional coagulation tests (CCT) and early lifesaving interventions (LSI) in pediatric trauma is unknown. METHODS: Severely injured patients (age ≤ 14 years) with an rTEG were retrospectively reviewed (8/1/2009-8/31/2011). Demographic and clinical information was collected. Spearman's correlation and regression models were used to evaluate rTEG with respect to CCT, early transfusion, LSI, and mortality. RESULTS: Eighty-six patients were identified. The median age was 8 years, and the median injury severity score (ISS) was 21. Activated clotting time (r=0.68), k-time (r=0.77), and α-angle (r=-0.75) showed strong correlation to PTT, and maximum amplitude (MA) (r=0.46) showed good correlation to platelet count (all p<0.001). When controlling for age, gender, and ISS, regression analysis showed that ACT, r-value, k-time, α-angle, and MA predicted red blood cell and plasma transfusion within 6h. MA (OR 0.82, 95% CI 0.70-0.96; p=0.018) was predictive of LSI. All rTEG values, except for LY30, predicted mortality. CONCLUSION: Admission rTEG correlates with CCT and predicts early transfusion, early LSI, and outcome in pediatric trauma. rTEG provides valuable data for goal-directed hemostatic resuscitation of critically injured children.

An emergency department thawed plasma protocol for severely injured patients.

IMPORTANCE: In an effort to expedite delivery of plasma for patients requiring massive transfusions, US medical centers began keeping thawed plasma (TP) in their blood banks (BBs), markedly reducing time to release of plasma; however, the time to transfusion was still excessively long. OBJECTIVE: To expedite delivery and transfusion of TP through implementation of an emergency department (ED) protocol. DESIGN AND SETTING: Retrospective cohort study in an American College of Surgeons-verified level I trauma center. PARTICIPANTS: Using the Trauma Registry of the American College of Surgeons database, we evaluated all adult trauma patients admitted from June 1, 2009, through August 31, 2010, who arrived directly from the scene, were the institution's highest level trauma activation, and received at least 1 U of red blood cells and 1 U of plasma in the first 6 hours after admission. The protocol was initiated in February 2010 by giving 4 U of AB plasma to patients in the ED. Patients were then divided into 2 groups: those admitted 8 months before (TP-BB) and 8 months after implementing TP location change (TP-ED). MAIN OUTCOME MEASURES: Primary outcome was time to first unit of plasma. Secondary outcomes included 24-hour blood use and 24-hour and 30-day mortality. RESULTS: A total of 294 patients met the study criteria (130 in the TP-BB group and 164 in the TP-ED). Although the patient demographics were similar, TP-ED patients had greater anatomical injury (median Injury Severity Score, 18 vs 25; P = .02) and more physiologic disturbances (median weighted Revised Trauma Score, 6.81 vs 3.83; P = .008). The TP-ED patients had a shorter time to first plasma transfusion (89 vs 43 minutes, P < .001). The TP-ED protocol was associated with a reduction in 24-hour transfusion of RBCs (P = .04), plasma (P = .04), and platelets (P < .001). Logistic regression identified TP-ED as an independent predictor of decreased 30-day mortality (odds ratio, 0.43; 95% CI, 0.194-0.956; P = .04). CONCLUSIONS: We demonstrated that implementation of an ED-TP protocol expedites transfusion of plasma to severely injured patients. This approach is associated with a reduction in overall blood product use and a 60% decreased odds in 30-day mortality.

Admission rapid thrombelastography can replace conventional coagulation tests in the emergency department: experience with 1974 consecutive trauma patients.

OBJECTIVE: Injury and shock lead to alterations in conventional coagulation tests (CCTs). Recently, rapid thrombelastography (r-TEG) has become recognized as a comprehensive assessment of coagulation abnormalities. We have previously shown that admission r-TEG results are available faster than CCTs and predict pulmonary embolism. We hypothesized that r-TEGs more reliably predict blood component transfusion than CCTs. METHODS: Consecutive patients admitted between September 2009 and February 2011 who met the highest-level trauma activations were included. All had admission r-TEG and CCTs. We correlated r-TEG values [activated clotting time (ACT), r, k, α, maximal amplitude (MA), LY30] with their corresponding CCTs [prothrombin time (PT)/activated partial thromboplastin time (aPTT), international normalized ratio (INR), platelet count and fibrinogen] for transfusion requirements. Charges were calculated for each test. Demographics, vital signs, and injury severity were recorded. RESULTS: We studied 1974 major trauma activations. The median injury severity score was 17 [interquartile range 9-26]; 25% were in shock; 28% were transfused; and 6% died within 24 hours. Overall, r-TEG correlated with CCTs. When controlling for age, injury mechanism, weighted-Revised Trauma Score, base excess and hemoglobin, ACT-predicted red blood cell (RBC) transfusion, and the α-angle predicted massive RBC transfusion better than PT/aPTT or INR (P < 0.001). The α-angle was superior to fibrinogen for predicting plasma transfusion (P < 0.001); MA was superior to platelet count for predicting platelet transfusion (P < 0.001); and LY-30 (rate of amplitude reduction 30 minutes after the MA is reached) documented fibrinolysis. These correlations improved for transfused, shocked or head injured patients. The charge for r-TEG ($317) was similar to the 5 CCTs ($286). CONCLUSIONS: The r-TEG data was clinically superior to results from 5 CCTs. In addition, r-TEG identified patients with an increased risk of early RBC, plasma and platelet transfusions, and fibrinolysis. Admission CCTs can be replaced with r-TEG.

Hyperfibrinolysis at admission is an uncommon but highly lethal event associated with shock and prehospital fluid administration.

BACKGROUND: Hyperfibrinolysis (HF) has been reported to occur in a range of 2% to 34% of trauma patients. Using rapid thromboelastography (r-TEG), we hypothesized that HF is (1) rarely present at admission on patients with severe injury and (2) associated with crystalloid hemodilution. To further strengthen this hypothesis, we created an in vitro hemodilution model to improve our mechanistic understanding of the early HF. METHODS: The trauma registry was queried for patients who were our highest-level trauma activations and admitted directly from the scene (October 2009-October 2010). HF was defined as more than 7.5% amplitude reduction 30 minutes after maximal amplitude (LY30). Using r-TEG, we then created an in vitro hemodilution model (0.9% NS) with and without tissue injury (addition of tissue factor and tissue plasminogen activator) to identify crystalloid volumes and injury needed to achieve specific LY30 values. RESULTS: Admission r-TEG values were captured on 1996 consecutive admissions. Only 41 patients (2%) had HF at admission r-TEG. The groups were similar in demographics. Compared with patients without HF, the HF group had more prehospital crystalloid (1.5 vs. 0.5 L), higher median Injury Severity Score (25 vs. 16), greater admission base deficit (20 vs. 2), and higher mortality (76% vs. 10%); all p < 0.001. Controlling for Injury Severity Score and base deficit on arrival, prehospital fluid was associated with a significant increase in likelihood of HF. In fact, each additional liter of crystalloid was associated with a 15% increased odds of HF. The in vitro model found that hemodilution to 15% of baseline and tissue factor + tissue plasminogen activator was required to achieve an LY30 of 50%. CONCLUSION: Although uncommon immediately after injury, HF is associated with prehospital crystalloid administration and shock at admission and is highly lethal. Our in vitro model confirms that tissue injury and significant crystalloid hemodilution result in severe and immediate HF.

Admission rapid thrombelastography predicts development of pulmonary embolism in trauma patients.

BACKGROUND: Injury leads to dramatic disturbances in coagulation with increased risk of bleeding followed by a hypercoagulable state. A comprehensive assessment of these coagulation abnormalities can be measured and described by thrombelastography. The purpose of this study was to identify whether admission rapid-thrombelastography (r-TEG) could identify patients at risk of developing pulmonary embolism (PE) during their hospital stay. METHODS: Patients admitted between September 2009 to February 2011 who met criteria for our highest-level trauma activation and were transported directly from the scene were included in the study. PE defined as clinically suspected and computed tomography angiography confirmed PE. We evaluated r-TEG values with particular attention to the maximal amplitude (mA) parameter that is indicative of overall clot strength. Demographics, vital signs, injury severity, and r-TEG values were then evaluated. In addition to r-TEG values, gender and injury severity score (ISS) were chosen a priori for developing a multiple logistic regression model predicting development of PE. RESULTS: r-TEG was obtained on 2,070 consecutive trauma activations. Of these, 2.5% (53) developed PE, 97.5% (2,017) did not develop PE. Patients in the PE group were older (median age, 41 vs. 33 years, p = 0.012) and more likely to be white (69% vs. 54%, p = 0.036). None of the patients in the PE group sustained penetrating injury (0% vs. 25% in the no-PE group, p < 0.001). The PE group also had admission higher mA values (66 vs. 63, p = 0.050) and higher ISS (median, 31 vs. 19, p = 0.002). When controlling for gender, race, age, and ISS, elevated mA at admission was an independent predictor of PE with an odds ratio of 3.5 for mA > 65 and 5.8 for mA > 72. CONCLUSION: Admission r-TEG mA values can identify patients with an increased risk of in-hospital PE. Further studies are needed to determine whether alternative anticoagulation strategies should be used for these high-risk patients. LEVEL OF EVIDENCE: Prognostic study, level III.

Rapid thrombelastography delivers real-time results that predict transfusion within 1 hour of admission.

BACKGROUND: Recognition of trauma-induced coagulopathy by conventional coagulation testing (CCT) is limited by their slow results, incomplete characterization, and their poor predictive nature. Rapid thrombelastography (r-TEG) delivers a more comprehensive assessment of the coagulation system but has not been prospectively validated in trauma patients. The purpose of this pilot study was to evaluate the timeliness of r-TEG results, their correlation with CCTs, and the ability of r-TEG to predict early blood transfusion. METHODS: Over a 5-month period, 583 consecutive major trauma activations were prospectively entered into a database, of which 272 met entry criteria. r-TEG and CCTs (prothrombin time, international normalized ratio, partial thromboplastin time, and platelet count) were obtained on all patients. Graphical results for r-TEG were displayed "real time" in the trauma bay. Spearman's correlation and regression models were used to compare r-TEG and CCTs. RESULTS: Early r-TEG values (activated clotting time [ACT], k-time, and r-value) were available within 5 minutes, late r-TEG values (maximal amplitude and α-angle) within 15 minutes, and CCTs within 48 minutes (p < 0.001). ACT, r-value, and k-time showed strong correlation with prothrombin time, international normalized ratio, and partial thromboplastin time (all r >0.70; p < 0.001), whereas maximal amplitude (r = -0.49) and α-angle (r = 0.40) correlated with platelet count (both p < 0.001). Linear regression demonstrated ACT predicted red blood cells (coef. 0.05; 95% confidence interval [CI], 0.04-0.06; p < 0.001), plasma (coef. 0.03; 95% CI, 0.02-0.04; p < 0.001), and platelet (coef. 0.06; 95% CI, 0.04-0.07; p < 0.001) transfusions within the first 2 hours of arrival. Controlling for all demographics and Emergency Department vitals, ACT >128 predicted massive transfusion (≥10 U) in the first 6 hours (odds ratio, 5.15; 95% CI, 1.36-19.49; p = 0.01). In addition, ACT <105 predicted patients who did not receive any transfusions in the first 24 hours (odds ratio, 2.80; CI, 1.02-7.07; p = 0.04). CONCLUSIONS: Graphical r-TEG results are available within minutes, correlate with conventional coagulation test that are not as rapidly available, and are predictive of early transfusions of packed red blood cells, plasma, and platelets.