Review of Thromboelastography in Neurocritical Care

The Role of Thromboelastography in Identifying Coagulopathy Among Geriatric Traumatic Brain Injury Patients

Background The geriatric population has the highest incidence of head injury, and those who are anticoagulated have an increased risk of traumatic intracranial hemorrhage (ICH). The availability of viscoelastic coagulation studies has coincided with the development of many anticoagulation reversal agents. In this study, our objective was to assess whether the thromboelastography (TEG) assay affected clinical decision-making regarding reversal agent administration among geriatric patients with ICH caused by blunt head trauma. Methodology We prospectively screened adults aged 65 and older with head trauma presenting to the emergency departments of two level-one trauma centers. International Classification of Diseases, Tenth Revision codes S00-09 were used to identify the diagnosis of head injury. Patients with CT head imaging positive for acute ICH were included. Each patient was assessed for home use of antiplatelet or anticoagulant medications, as well as in-hospital use of any reversal agents. Reversal agent administration and mortality were compared between patients who received TEG and those who did not. Results A total of 680 patients had acute ICH on head CT, and 324 (48%) patients received TEG. More patients screened with TEG were transfused platelets (30.2% vs. 10.7%, p < 0.001). This remained significant for patients taking anticoagulants, antiplatelets, or neither. There were no differences in the administration of other reversal agents (prothrombin complex concentrate or fresh frozen plasma) or mortality whether or not TEG was performed. Conclusions Patients who had TEG performed were more likely to receive platelet reversal agents, regardless of antiplatelet medication usage. Among elderly adults with ICH, TEG is a rapid screening test that may help identify patients with platelet function abnormalities requiring reversal.

Appraising the use of tranexamic acid in traumatic and non‐traumatic intracranial hemorrhage: A narrative review

Recently there has been increasing interest and debate on the use of tranexamic acid (TXA), an antifibrinolytic drug, in both traumatic and non‐traumatic intracranial hemorrhage. In this review we aim to discuss recent investigations looking at TXA in traumatic brain injury (TBI) and different categories of spontaneous intracranial hemorrhage. We also discuss differences between setting (hospital vs pre‐hospital), dosing and timing strategies, and other logistical challenges surrounding optimal use of TXA for isolated intracranial hemorrhage. Last, we hope to provide guidance for clinicians when considering the use of TXA in a patient with traumatic or non‐traumatic intracranial hemorrhage based on appraisal of the available literature as well as some potential ideas for future research in this area.

Viscoelastic Testing in Traumatic Brain Injury: Key Research Insights

The role of viscoelastic testing in the evaluation and management of traumatic brain injury (TBI) remains a subject of ongoing exploration. This review highlights four key publications that provide significant insights into this subject. Holcomb et al. provided early evidence of the relationship between thromboelastography (TEG) and conventional coagulation tests (CCTs). Later, Samuels et al. used TEG to identify a unique coagulopathy phenotype in TBI characterized by a notable absence of fibrinolytic abnormalities. Dixon et al. built upon these findings by exploring the application of TEG in the context of antifibrinolytic administration, noting a similar lack of effect on LY30. Finally, Guillotte et al. demonstrated the utility of TEG-PM in assessing platelet dysfunction in TBI. While these studies provide key early support for the utility of viscoelastic testing in the TBI, further exploration is needed to define evidence-based guidelines for clinical application.

Antithrombotic regimens and need for critical care interventions among patients with subdural hematomas

BACKGROUND

Antithrombotic-associated subdural hematomas (SDHs) are increasingly common, and the possibility of clinical deterioration in otherwise stable antithrombotic-associated SDH patients may prompt unnecessary admissions to intensive care units. It is unknown whether all antithrombotic regimens are equally associated with the need for critical care interventions. We sought to compare the frequency of critical care interventions and poor functional outcomes among three cohorts of noncomatose SDH patients: patients on no antithrombotics, patients on anticoagulants, and patients on antiplatelets alone.

METHODS

We performed a retrospective cohort study on all noncomatose SDH patients (Glasgow Coma Scale > 12) presenting to an academic health system in 2018. The three groups of patients were compared in terms of clinical course and functional outcome. Multivariable logistic regression was used to determine predictors of need for critical care interventions and poor functional outcome at hospital discharge.

RESULTS

There were 281 eligible patients presenting with SDHs in 2018, with 126 (45%) patients on no antithrombotics, 106 (38%) patients on antiplatelet medications alone, and 49 (17%) patients on anticoagulants. Significant predictors of critical care interventions were coagulopathy (OR 5.1, P < 0.001), presence of contusions (OR 3, P = 0.007), midline shift (OR 3.4, P = 0.002), and maximum SDH thickness (OR 2.4, P = 0.002). Significant predictors of poor functional outcome were age (OR 1.8, P < 0.001), admission Glasgow Coma Scale score (OR 0.3, P < 0.001), dementia history (OR 4.2, P = 0.001), and coagulopathy (OR 3.5, P = 0.02). Isolated antiplatelet use was not associated with either critical care interventions or functional outcome.

CONCLUSION

Isolated antiplatelet use is not a significant predictor of need for critical care interventions or poor functional outcome among SDH patients and should not be used as a criterion for triage to the intensive care unit.

Management of Severe Bleeding in Patients Treated With Oral Anticoagulants: Proceedings Monograph From the Emergency Medicine Cardiac Research and Education Group-International Multidisciplinary Severe Bleeding Consensus Panel October 20, 2018

In this Emergency Medicine Cardiac Research and Education Group (EMCREG)-International Proceedings Monograph from the October 20, 2018, EMCREG-International Multidisciplinary Consensus Panel on Management of Severe Bleeding in Patients Treated With Oral Anticoagulants held in Orlando, FL, you will find a detailed discussion regarding the treatment of patients requiring anticoagulation and the reversal of anticoagulation for patients with severe bleeding. For emergency physicians, critical care physicians, hospitalists, cardiologists, internists, surgeons, and family physicians, the current approach and disease indications for treatment with anticoagulants such as coumadin, factor IIa, and factor Xa inhibitors are particularly relevant. When a patient treated with anticoagulants presents to the emergency department, intensive care unit, or operating room with severe, uncontrollable bleeding, achieving rapid, controlled hemostasis is critically important to save the patient's life. This EMCREG-International Proceedings Monograph contains multiple sections reflecting critical input from experts in Emergency Cardiovascular Care, Prehospital Emergency Medical Services, Emergency Medicine Operations, Hematology, Hospital Medicine, Neurocritical Care, Cardiovascular Critical Care, Cardiac Electrophysiology, Cardiology, Trauma and Acute Care Surgery, and Pharmacy. The first section provides a description of the current indications for the treatment of patients using oral anticoagulants including coumadin, the factor IIa (thrombin) inhibitor dabigatran, and factor Xa inhibitors such as apixaban and rivaroxaban. In the remaining sections, the treatment of patients presenting to the hospital with major bleeding becomes the focus. The replacement of blood components including red blood cells, platelets, and clotting factors is the critically important initial treatment for these individuals. Reversing the anticoagulated state is also necessary. For patients treated with coumadin, infusion of vitamin K helps to initiate the process of protein synthesis for the vitamin K-dependent coagulation proteins II, VII, IX, and X and the antithrombotic protein C and protein S. Repletion of clotting factors for the patient with 4-factor prothrombin complex concentrate, which includes factors II (prothrombin), VII, IX, and X and therapeutically effective concentrations of the regulatory proteins (protein C and S), provides real-time ability to slow bleeding. For patients treated with the thrombin inhibitor dabigatran, treatment using the highly specific, antibody-derived idarucizumab has been demonstrated to reverse the hypocoagulable state of the patient to allow blood clotting. In May 2018, andexanet alfa was approved by the US Food and Drug Administration to reverse the factor Xa anticoagulants apixaban and rivaroxaban in patients with major bleeding. Before the availability of this highly specific agent, therapy for patients treated with factor Xa inhibitors presenting with severe bleeding usually included replacement of lost blood components including red blood cells, platelets, and clotting factors and 4-factor prothrombin complex concentrate, or if not available, fresh frozen plasma. The evaluation and treatment of the patient with severe bleeding as a complication of oral anticoagulant therapy are discussed from the viewpoint of the emergency physician, neurocritical and cardiovascular critical care intensivist, hematologist, trauma and acute care surgeon, hospitalist, cardiologist, electrophysiologist, and pharmacist in an approach we hope that the reader will find extremely practical and clinically useful. The clinician learner will also find the discussion of the resumption of oral anticoagulation for the patient with severe bleeding after effective treatment important because returning the patient to an anticoagulated state as soon as feasible and safe prevents thrombotic complications. Finally, an EMCREG-International Severe Bleeding Consensus Panel algorithm for the approach to management of patients with life-threatening oral anticoagulant-associated bleeding is provided for the clinician and can be expanded in size for use in a treatment area such as the emergency department or critical care unit.

The ability of thromboelastography parameters to predict severe pre-eclampsia when measured during early pregnancy

OBJECTIVE

To examine the predictive value of thromboelastography parameters during early pregnancy as potential markers of severe pre-eclampsia during late pregnancy.

METHODS

An observational retrospective case-control study was conducted among pregnant women who attended a single hospital in Shanghai, China, between July 1, 2016, and February 31, 2018. Data were obtained from medical records and a structured questionnaire completed by the participants. Thromboelastography parameters included time r; time k; α angle; maximum amplitude; clot lysis at 60 minutes; and coagulation index. Other risk factors for severe pre-eclampsia were also assessed.

RESULTS

The pre-eclampsia and control groups comprised 46 and 138 women, respectively. Women with a coagulation index below zero at 13-20 weeks experienced an increased risk of severe pre-eclampsia (odds ratio [OR] 31.72, 95% confidence interval [CI] 11.28-89.24; P<0.001). Other risk factors for severe pre-eclampsia were family history of hypertension (OR 3.79, 95% CI 1.21-11.48; P=0.017) and pre-pregnancy body mass index (OR 2.83, 95% CI 1.14-7.36; P=0.023).

CONCLUSION

Coagulation index determined by thromboelastography was an early marker for severe pre-eclampsia.

Effects of platelet dysfunction and platelet transfusion on outcomes in traumatic brain injury patients

OBJECTIVE

Platelet inhibition in traumatic brain injury (TBI) may be due to injury or antiplatelet medication use pre-injury. This study aims to identify factors associated with increased platelet arachidonic acid (AA) and adenosine diphosphate (ADP) inhibition and determine if platelet transfusion reduces platelet dysfunction and affects outcome.

METHODS

Prospective thromboelastography (TEG) assays were collected on adult patients with TBI with intracranial injuries detected by computed tomography (CT). Outcomes included in-hospital mortality, and CT lesion expansion.

RESULTS

Of 153 patients, ADP inhibition was increased in moderate and severe TBI compared to mild TBI (p = 0.0011). P2Y12 inhibiting medications had increased ADP inhibition (p = 0.0077). Admission ADP inhibition was not associated with in-hospital mortality (p = 0.24) or CT lesion expansion (p = 0.94). Mean reduction of ADP inhibition from platelet transfusion (-15.1%) relative to no transfusion (+ 11.7%) was not statistically different (p = 0.0472).

CONCLUSIONS

Mild TBI results in less ADP inhibition compared to moderate and severe TBI, suggesting a dose response relationship between TBI severity and degree of platelet dysfunction. Further, study is warranted to determine efficacy and parameters for platelet transfusion in patients with TBI.

Neurosurgical applications of viscoelastic hemostatic assays

Patients taking antithrombotic agents are very common in neurosurgical practice. The perioperative management of these patients can be extremely challenging especially as newer agents, with poorly defined laboratory monitoring and reversal strategies, become more prevalent. This is especially true with emergent cases in which rapid reversal of anticoagulation is required and the patient’s exact medical history is not available. With an aging patient population and the associated increase in diseases such as atrial fibrillation, it is expected that the use of these agents will continue to rise in coming years. Furthermore, thromboembolic complications such as deep venous thrombosis, pulmonary embolism, and myocardial infarction are common complications of major surgery. These trends, in conjunction with a growing understanding of the hemostatic process and its contribution to the pathophysiology of disease, stress the importance of the complete evaluation of a patient’s hemostatic profile in guiding management decisions. Viscoelastic hemostatic assays (VHAs), such as thromboelastography and rotational thromboelastometry, are global assessments of coagulation that account for the cellular and plasma components of coagulation. This FDA-approved technology has been available for decades and has been widely used in cardiac surgery and liver transplantation. Although VHAs were cumbersome in the past, advances in software and design have made them more accurate, reliable, and accessible to the neurosurgeon. VHAs have demonstrated utility in guiding intraoperative blood product transfusion, identifying coagulopathy in trauma, and managing postoperative thromboprophylaxis. The first half of this review aims to evaluate and assess VHAs, while the latter half seeks to appraise the evidence supporting their use in neurosurgical populations.