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.