Viscoelastic monitoring in trauma resuscitation

The TEG 5000 System: System Description and Protocol for Measurements

The thromboelastograph (TEG) has undergone several modifications, but the concept on which the original TEG was based (cup and pin technology) remained up to the TEG 5000 analyzer (Haemonetics, Braintree, MA). In a previous chapter, we reviewed the advantages and limitations of TEG 5000 as well as factors that affect TEG and which must be considered when interpreting tracings. In the present chapter, we provide a description of the TEG 5000 principle and its operation protocol.

Is ROTEM Diagnostic in Trauma Care Associated with Lower Mortality Rates in Bleeding Patients?—A Retrospective Analysis of 7461 Patients Derived from the TraumaRegister DGU®

Introduction: Death from uncontrolled trauma haemorrhage and subsequent trauma-induced coagulopathy (TIC) is potentially preventable. Point-of-care devices such as rotational thromboelastometry (ROTEM^®) are advocated to detect haemostatic derangements more rapidly than conventional laboratory diagnostics. Regarding reductions in RBC transfusion, the use of ROTEM has been described as being efficient and associated with positive outcomes in several studies. Objective: The effect of ROTEM use was assessed on three different outcome variables: (i) administration of haemostatics, (ii) rate of RBC transfusions and (iii) mortality in severely injured patients. Methods and Material: A retrospective analysis of a large data set of severely injured patients collected into the TraumaRegister DGU^® between 2009 and 2016 was conducted. The data of 7461 patients corresponded to the inclusion criteria and were subdivided into ROTEM-using and ROTEM-non-using groups. Both groups were analysed regarding (i) administration of haemostatics, (ii) rate of RBC transfusions and (iii) mortality. Results: A lower mortality rate in ROTEM-using groups was observed (p = 0.043). Furthermore, more patients received haemostatic medication when ROTEM was used. In ROTEM-using groups, there was a statistically relevant higher application of massive transfusion. Conclusions: In this retrospective study, the use of ROTEM was associated with reduced mortality and an increased application of haemostatics and RBC transfusions. Prospective evidence is needed for further evidence-based recommendations.

Association of Thromboelastography with Progression of Hemorrhagic Injury in Children with Traumatic Brain Injury

INTRODUCTION

Progression of hemorrhagic injury (PHI) in children with traumatic brain injury portends poor outcomes. The association between thromboelastography (TEG), functional coagulation assays, and PHI is not well characterized in children.

METHODS

This was a retrospective cohort study of children presenting with PHI at a pediatric level I academic trauma center from 2015 to 2020. Inclusion criteria were as follows: age less than 18 years, intracranial hemorrhage on admission head computed tomography scan, and admission rapid TEG assay and conventional coagulation tests. PHI was defined by the following radiographic criteria: any expansion of or new intracranial hemorrhage on subsequent head computed tomography scan. Rapid TEG values included Activated Clotting Time (ACT), alpha angle, maximum amplitude, and lysis at 30 min. Wilcoxon rank-sum test was used to assess baseline differences between groups with PHI and without PHI, including laboratory assays. Univariate analysis was performed to examine the association between variables of interest and PHI. Patients were dichotomized on the basis of this cut point to generate a "low ACT" group and a "high ACT" group. These variables were included in a multivariable logistic regression model to determine independent association with traumatic brain injury progression.

RESULTS

In total, 219 patients met criteria for analysis. In this cohort, the median (interquartile range [IQR]) age = 6 (2-12) years, median (IQR) Injury Severity Score = 21 (11-27), 68% were boys, and 69% sustained blunt injury. The rate of PHI was 25% (54). Median (IQR) time to PHI was 1 (0-4) days. Children with PHI had a higher Injury Severity Score (p < 0.001), lower Glasgow Coma Scale (p < 0.001), greater incidence of shock (p = 0.04), and lower admission hemoglobin (p = 0.02) compared with those without PHI. Children with PHI had a higher International Normalized Ratio (INR) and longer TEG-ACT; other TEG values (alpha angle, maximum amplitude, and lysis at 30 min) were not associated with PHI. In the logistic regression model accounting for other covariates associated with PHI, elevated ACT remained an independent predictor of progression (odds ratio = 2.25, 95% confidence interval 1.09-4.66; p = 0.03; area under the receiver operating characteristic curve = 0.76). After adjusting for confounders, INR fell out of the model and was not an independent predictor of progression (odds ratio = 1.32, 95% confidence interval 0.60-2.93; p = 0.49).

CONCLUSIONS

Although INR was elevated in children with PHI and has been associated with poor clinical outcomes, only admission TEG-ACT was independently associated with PHI. Further study is warranted to determine whether TEG-ACT reflects an actionable therapeutic target.

Impact of general anesthesia on rotational thromboelastometry (ROTEM) parameters and standard plasmatic coagulation tests in healthy Beagle dogs

OBJECTIVE

To assess the influence of general anesthesia on rotational thromboelastometry (ROTEM) and standard coagulation testing in healthy dogs.

STUDY DESIGN

Prospective experimental study.

ANIMALS

10 healthy Beagle dogs.

METHODS

Dogs were administered methadone (0.2 mg/kg) intramuscularly. Anesthesia was co-induced intravenously 30 min later with midazolam (0.1 mg/kg) and propofol to effect, and maintained with sevoflurane. Crystalloids were administered at 5 ml/kg/h. Blood was sampled by direct venipuncture before induction (T0) and 3.5 h later (T3.5) and ROTEM parameters (ExTEM, InTEM, FibTEM, ApTEM), standard plasmatic coagulation tests (prothrombin time [PT], activated partial thromboplastin time [aPTT], fibrinogen concentration), hematology, ionized calcium, triglycerides, pH, lactate and body temperature were compared over time with Students t - test or Wilcoxon matched pairs signed-rank tests.

RESULTS

The following variables dropped significantly between T0 and T3.5: body temperature (p < 0.0001), hematocrit (p < 0.0001), platelet count (p < 0.01), pH (p < 0.01), triglycerides (p < 0.01), fibrinogen concentration (p < 0.01), ExTEM, FibTEM (p < 0.01) and ApTEM (p < 0.05) clotting times. Lactate concentration (p < 0.01), aPTT (p < 0.05) and FibTEM maximum clot firmness increased (p < 0.05). No changes were noted in ionized calcium, PT and InTEM values.

CONCLUSION AND CLINICAL RELEVANCE

General anesthesia with concurrent hemodilution and hypothermia induced significant but clinically irrelevant changes in coagulation variables measured at 37 °Celsius. Blood samples from anaesthetized animals can be used for determination of coagulation status in dogs.

Viscoelastic Testing and Coagulopathy of Traumatic Brain Injury

A unique coagulopathy often manifests following traumatic brain injury, leading the clinician down a difficult decision path on appropriate prophylaxis and therapy. Conventional coagulation assays—such as prothrombin time, partial thromboplastin time, and international normalized ratio—have historically been utilized to assess hemostasis and guide treatment following traumatic brain injury. However, these plasma-based assays alone often lack the sensitivity to diagnose and adequately treat coagulopathy associated with traumatic brain injury. Here, we review the whole blood coagulation assays termed viscoelastic tests and their use in traumatic brain injury. Modified viscoelastic tests with platelet function assays have helped elucidate the underlying pathophysiology and guide clinical decisions in a goal-directed fashion. Platelet dysfunction appears to underlie most coagulopathies in this patient population, particularly at the adenosine diphosphate and/or arachidonic acid receptors. Future research will focus not only on the utility of viscoelastic tests in diagnosing coagulopathy in traumatic brain injury, but also on better defining the use of these tests as evidence-based and/or precision-based tools to improve patient outcomes.