Use of Thromboelastography (TEG) for Detection of New Oral Anticoagulants

The 2023 WSES guidelines on the management of trauma in elderly and frail patients

BACKGROUND

The trauma mortality rate is higher in the elderly compared with younger patients. Ageing is associated with physiological changes in multiple systems and correlated with frailty. Frailty is a risk factor for mortality in elderly trauma patients. We aim to provide evidence-based guidelines for the management of geriatric trauma patients to improve it and reduce futile procedures.

METHODS

Six working groups of expert acute care and trauma surgeons reviewed extensively the literature according to the topic and the PICO question assigned. Statements and recommendations were assessed according to the GRADE methodology and approved by a consensus of experts in the field at the 10th international congress of the WSES in 2023.

RESULTS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage, including drug history, frailty assessment, nutritional status, and early activation of trauma protocol to improve outcomes. Acute trauma pain in the elderly has to be managed in a multimodal analgesic approach, to avoid side effects of opioid use. Antibiotic prophylaxis is recommended in penetrating (abdominal, thoracic) trauma, in severely burned and in open fractures elderly patients to decrease septic complications. Antibiotics are not recommended in blunt trauma in the absence of signs of sepsis and septic shock. Venous thromboembolism prophylaxis with LMWH or UFH should be administrated as soon as possible in high and moderate-risk elderly trauma patients according to the renal function, weight of the patient and bleeding risk. A palliative care team should be involved as soon as possible to discuss the end of life in a multidisciplinary approach considering the patient's directives, family feelings and representatives' desires, and all decisions should be shared.

CONCLUSIONS

The management of elderly trauma patients requires knowledge of ageing physiology, a focused triage based on assessing frailty and early activation of trauma protocol to improve outcomes. Geriatric Intensive Care Units are needed to care for elderly and frail trauma patients in a multidisciplinary approach to decrease mortality and improve outcomes.

Effect of bivalirudin on coagulation in neonatal (cord) and adult human blood in vitro

INTRODUCTION

Bivalirudin is recommended as an alternative to heparin in cardiac surgery with cardiopulmonary bypass. Although it has been used in infants and children for this indication, there is a paucity of data on the pharmacologic effects of bivalirudin in neonates. Given the immaturity of the hemostatic system in neonates, we hypothesized that coagulation responses to bivalirudin in this population would be different than in adults.

METHODS

Blood samples were drawn from placenta-cord units and from healthy adult donors. The study was carried out in two steps. First, bivalirudin was added to cord and adult blood samples at concentrations of 0, 5, 10, 15, and 20 μg/mL. Activated clotting time and thromboelastographic variables were recorded. Next, we used a Chandler loop system to assess the efficacy of bivalirudin in a simple model of cardiopulmonary bypass. The loops were primed with cord or adult blood and were run until thrombus was detected. Plasma bivalirudin concentrations were measured at 1, 15, 30, 45, 60, and 75 min after initiating rotation of the loops using liquid chromatography/mass spectrometry.

RESULTS

Bivalirudin elicited a dose-dependent prolongation inhibition of coagulation in both cord and adult blood samples with greater potency in cord blood in comparison to adult blood (activated clotting time: 627 ± 50 vs. 452 ± 22 s at 15 μg/mL bivalirudin, p < .0001). This relative potency was also demonstrated in the Chandler loop system, but interestingly, cord blood appeared to inactivate bivalirudin more rapidly than adult blood with earlier clotting in loops containing cord blood.

CONCLUSIONS

This study demonstrates that bivalirudin has greater potency in cord blood in vitro than in adult blood. Plasma degradation appears to proceed more rapidly in cord blood than in adults. Both of these findings should be considered when planning dosing regimens in neonatal patients.

A comparative in vitro study of the anticoagulant effect of branded versus generic rivaroxaban

BACKGROUND

Several generic formulations of rivaroxaban were recently marketed to be used interchangeably with their branded equivalent. However, there have been no previously published studies that directly compared the in vitro anticoagulant effect of branded vs. generic rivaroxaban. The aim of this in vitro study was to compare the effects of three raw rivaroxaban materials, obtained from the branded (Xarelto®) and two generic (Rivarolto® and Rivaroxaban Sandoz®) rivaroxaban formulations on an array of coagulation assays.

METHODS

A pool of normal plasma was spiked with several concentrations of the three rivaroxaban (range 50-750 ng/ml). The concentrations were assessed with a rivaroxaban calibrated anti-Xa assay and confirmed by ultra-high-performance liquid chromatography-mass spectrometry coupled with tandem mass spectrometry (UHPLC-MS/MS). The following assays were performed: Prothrombin time (PT), activated Partial Thromboplastin time (aPTT), Diluted Russell's Viper Venom Test (dRVVT), Thrombin time (TT), Clauss Fibrinogen, Factor VII, VIII and IX assays, and thromboelastography.

RESULTS

The results obtained by the three rivaroxaban at similar concentrations were comparable. Increasing concentrations of the three rivaroxaban showed a strong positive correlation with the PT, aPTT and dRVVT assays (r > 0.95, p < 0.01 for all), and a strong negative correlation with the Factors assays (r < -0.95, p < 0.01 for all). TT and Clauss Fibrinogen were not affected by rivaroxaban. No significant difference was identified in the mean assays' results obtained by the three rivaroxaban.

CONCLUSION

This study showed that the branded and generic rivaroxaban exert an identical in vitro anticoagulant effect across a wide range of concentrations.

Viscoelastic Testing Methods

Viscoelastic testing methods examine the real-time formation of a clot in a whole blood sample, and include thromboelastography (TEG), rotational thromboelastometry (ROTEM), and several other testing platforms. They allow for concurrent assessment of multiple aspects of clotting, including plasmatic coagulation factors, platelets, fibrinogen, and the fibrinolytic pathway. This testing is rapid and may be performed at the point-of-care, allowing for prompt identification of coagulopathies to guide focused and rational administration of blood products as well as the identification of anticoagulant effect. With recent industry progression towards user-friendly, cartridge-based, portable instruments, viscoelastic testing has emerged in the 21st century as a powerful tool to guide blood transfusions in the bleeding patient, and to identify and treat both bleeding and thrombotic conditions in many operative settings, including trauma surgery, liver transplant surgery, cardiac surgery, and obstetrics. In these settings, the use of transfusion algorithms guided by viscoelastic testing data has resulted in widespread improvements in patient blood management as well as modest improvements in select patient outcomes. To address the increasingly wide adoption of viscoelastic methods and the growing number of medical and laboratory personnel tasked with implementing, performing, and interpreting these methods, this chapter provides an overview of the history, physiology, and technology behind viscoelastic testing, as well as a practical review of its clinical utility and current evidence supporting its use. Also included is a review of testing limitations and the contextual role played by viscoelastic methods among all coagulation laboratory testing.

Case Report: Extended Duration Andexanet Alfa Infusion in a Surgical Trauma Patient

Background: Andexanet alfa (andexanet) is the only FDA-approved medication for reversal of apixaban and rivaroxaban anticoagulation for life-threatening or uncontrolled bleeding. Infusion modifications may be required in surgical patients undergoing prolonged operative intervention but have not previously been described. Case Report: A 78-year-old woman on rivaroxaban for atrial fibrillation was admitted to the trauma service for a mechanical fall, sustaining a T4 burst fracture with severe canal stenosis and spinal cord edema resulting in loss of strength and sensation in her legs. Clinically relevant rivaroxaban activity was verified with an elevated low molecular weight heparin anti-factor Xa assay, and laboratory confirmed coagulopathy was demonstrated by a prolonged prothrombin time, thromboelastography (TEG) R-time, and activated clotting time (ACT). The patient required urgent surgical intervention for spinal fixation. Given the expected prolonged duration of the procedure, standard dose andexanet was initiated with a prolonged infusion at half the standard rate during the operation. The procedure was successful and intraoperative TEGs demonstrated normalization of R-time and ACT throughout the procedure. The patient did not experience any complications postoperatively and successfully discharged to inpatient rehabilitation. Conclusion: Modifications to the andexanet infusion may be required in surgical patients requiring rivaroxaban reversal for a prolonged procedure. Further data are needed to determine the optimal approach to infusion modification.

A Review of Thromboelastography for Nurses

BACKGROUND

Thromboelastography is a viscoelastic test with multiple potential advantages over conventional coagulation tests in various disease states. Thromboelastography rapidly provides qualitative and quantitative information related to a patient's coagulation status.

OBJECTIVE

To describe recent studies of the use of thromboelastography in various clinical states and how thromboelastography is used in coagulation management.

METHODS

A literature review using the MEDLINE and PubMed databases was conducted. The updated methodology for integrated reviews by Whittemore and Knafl was followed. Coauthors evaluated separate areas that were independently reviewed by other coauthors to ensure appropriateness for inclusion.

RESULTS

The use of thromboelastography for various clinical conditions with challenging hemostatic profiles has increased. This integrative review covers the use of thromboelastography in patients with trauma, medication-induced coagulopathy, acute and chronic liver failure, and cardiothoracic surgery. Potential future directions are also discussed.

DISCUSSION

Thromboelastography has numerous potential benefits over conventional coagulation tests for assessing coagulation status in patients in various clinical states. Nurses can support clinical decisions to use the most appropriate test for their patients.

CONCLUSIONS

Each team member should be involved in assessing the usefulness of thromboelastography. Critical care nurses and the multidisciplinary team must identify patients in whom its use is warranted, interpret the results, and provide appropriate interventions in response to the results and clinical status of the patient.

Thromboelastography in the Perioperative Period: A Literature Review

Assessing coagulation status is essential for prompt intervention to reduce morbidity and mortality related to bleeding and thrombotic complications during the perioperative period. Traditional coagulation tests such as platelet count, activated partial thromboplastin time (aPTT), prothrombin time (PT), international normalized ratio (INR), and activated clotting time (ACT) provide only static evaluation. These tests are not designed for assessment of dynamically changing coagulation conditions during the perioperative time. However, viscoelastic coagulation testing such as thromboelastography (TEG) produces a rapid numerical and graphical representation that helps to detect and direct targeted hemostatic therapy. Searching the literature through PubMed, Medline, Ovid, CINAHL, and ClinicalTrials.gov we retrieved 210 studies, which represent the use of TEG in the perioperative period. The included studies were categorized under various settings such as trauma, obstetrics, orthopedics, intensive care unit (ICU), cardiovascular, transplant, and miscellaneous scenarios. TEG showed promising results in trauma surgeries in predicting mortality, hypercoagulability, and bleeding even when it was compared to conventional methods. TEG was also useful in monitoring anticoagulant therapy in orthopedic and obstetric surgeries; however, its role in predicting thrombotic events, hypercoagulability, or complications was questionable. In ICU patients, it showed promising results, especially in the prediction or improvement of sepsis, coagulopathy, thrombotic events, ICU duration, hospital stay, and ventilator duration. TEG parameters effectively predicted hypercoagulation in transplant surgeries. Regarding cardiovascular surgeries, they were effective in the prediction of the need for blood products, coagulopathy, thrombotic events, and monitoring anticoagulation therapy. More randomized clinical trials comparing TEG parameters with standardized tools are needed to produce robust results to standardize its use in different perioperative settings.

Utility of Thromboelastography in Detecting NOAC-Related Coagulopathy in Traumatic Brain Injury

INTRODUCTION

Novel oral anticoagulants (NOACs) have gained popularity as a vitamin K antagonist alternative without regular monitoring. There has been an increase in elderly patients on NOACs admitted for traumatic brain injury (TBI). The aim of this study is to determine the efficacy of thromboelastography (TEG) in detecting NOAC-related coagulopathy among TBI patients.

METHODS

A retrospective chart review of 456 TBI patients admitted to Sentara Norfolk General Hospital from 2015 to 2020 was performed. Inclusion criteria comprised patients on NOACs with a TEG performed at presentation (66 patients). Analysis included TEG values, use of prothrombin complex concentrate factor 4 (PCC4), increased intracranial hemorrhage on repeat head computed tomography within 24 h of admission, and mortality.

RESULTS

TEG results showed 0% elevated reaction time, 1.5% elevated kinetics time, 1.5% low alpha angle, 4.5% low max amplitude, and 3.0% elevated clot lysis percent at 30 min in our cohort. Despite overwhelmingly normal TEG results, 42.42% of patients received PCC4. A subset analysis of these patients compared to those who did not receive PCC4, revealed a higher frequency of increased intracranial hemorrhage on repeat head computed tomography within 24 h of admission (42.86% versus 18.42%, P = 0.03), and increased mortality (25.0% versus 5.26%, P = 0.0219). Patients who did not receive PCC4 had no increased frequency of operative intervention or worsening of Glasgow Coma Score.

CONCLUSIONS

Results suggest that TEG does not reliably assess NOAC-related coagulopathy in TBI patients. Caution must be used when interpreting TEG data to determine reversal strategies in TBI patients on NOACs.

The impact of direct oral anticoagulants on viscoelastic testing - A systematic review

BACKGROUND

In case of bleeding patients and in acute care, the assessment of residual direct oral anticoagulant (DOAC) activity is essential for evaluating the potential impact on hemostasis, especially when a timely decision on urgent surgery or intervention is required. Viscoelastic tests are crucial in a modern goal-directed coagulation management to assess patients' coagulation status. However, the role of viscoelastic test to detect and quantify residual DOAC plasma levels is controversially discussed. The aim of this review was to systematically summarize the evidence of viscoelastic tests for the assessment of residual DOAC activity.

METHOD

PubMed, Embase, Scopus, and the Cochrane Library were searched for original articles investigating the effect of rivaroxaban, apixaban, edoxaban, or dabigatran plasma levels on different viscoelastic tests of the adult population from database inception to December 31, 2021.

RESULTS

We included 53 studies from which 31 assessed rivaroxaban, 22 apixaban, six edoxaban, and 29 dabigatran. The performance of viscoelastic tests varied across DOACs and assays. DOAC specific assays are more sensitive than unspecific assays. The plasma concentration of rivaroxaban and dabigatran correlates strongly with the ROTEM EXTEM, ClotPro RVV-test or ECA-test clotting time (CT) and TEG 6s anti-factor Xa (AFXa) or direct thrombin inhibitor (DTI) channel reaction time (R). Results of clotting time (CT) and reaction time (R) within the normal range do not reliable exclude relevant residual DOAC plasma levels limiting the clinical utility of viscoelastic assays in this context.

CONCLUSION

Viscoelastic test assays can provide fast and essential point-of-care information regarding DOAC activity, especially DOAC specific assays. The identification and quantification of residual DOAC plasma concentration with DOAC unspecific viscoelastic assays are not sensitive enough, compared to recommended anti-Xa activity laboratory measurements.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=320629], identifier [CRD42022320629].

Thrombodynamics Test in Assessing the Risk of Thrombus Formation in Patients with Atrial Fibrillation Taking Direct Oral Anticoagulants

Aim. To evaluate thrombus characteristics in patients with atrial fibrillation (AF) taking different direct oral anticoagulants (DOACs) using Thrombodynamics test.Materials and methods. Thrombodynamics test was performed in 100 patients with paroxysmal and permanent forms of AF taking different DOACs, dose choice was done in accordance with the instructions for drugs use. For analysis samples of fresh citrated platelet-free plasma were taken just before regular DOACs dose intake (trough concentration). Statistical data processing was carried out using R software packages.Results. All patients had no history of thrombosis or bleeding before inclusion in this study. All parameters of Thrombodynamics test taken at residual concentration of DOACs were in general within reference values, that is in the area of normal coagulation: spatial clot growth rate (V) – 26.56 (25.0; 29.2) μm/min, the time to the start of clot growth (Tlag) – 1.05 (0.85; 1.27) min, initial spatial clot growth rate (Vi) – 44.3±7.7 μm/min, stationary spatial clot growth rate (Vst) – 26.5 (24.9; 28.4) μm/min, clot size (CS) – 999.7 (912.9; 1084.7) μm, clot density (D) – 22883.1±3199.9 arb. units. D was appeared to be higher in women [22947.7 (21477.5; 22947.7) vs men [22124.8 (19722.8; 22124.8), p=0.035] and Tlag was significantly higher in patients with chronic heart failure [1.2 (1.0; 1.2) vs 1.0 (0.8; 1.0), p=0.008]. A correlation was found between level of creatinine and Tlag parameter, glomerular filtration rate (GFR) and clot density. With an increase in the level of creatinine in the blood and a decrease in GFR, respectively, there was an increase in Tlag parameter (p-value 0.038); with an increase in GFR, clot density decrease (p-value 0.005).

Conclusion. All parameters of Thrombodynamics test on residual concentration of DOACs were within reference values that indicated optimal anticoagulant effect of all DOACs. The obtained data of normal coagulation at the residual concentration of the anticoagulant are consistent with the previously obtained data on the safety and effectiveness of DOACs using other methods. Further studies with clinical end points are needed to assess the clinical value of this method.

Application of Activators Ecarin and Factor Xa in Thrombelastography for Measurement of Anticoagulant Effect of Direct Oral Anticoagulants Using TEG 5000

There are situations where monitoring direct oral anticoagulants (DOACs) would be useful, including bleedings and trauma. The thromboelastographic technique has proven useful in bleeding situations in trauma and heart surgery. The aim of this study was to examine the effect of DOACs on all currently commercially available conventional TEG®5000 assays as well as novel modified assay using Ecarin and human factor Xa (HFXa). Healthy male volunteers were given single dose of oral dabigatran 150 mg, rivaroxaban 20 mg, or apixaban 5 mg. Kaolin, RapidTEG, functional fibrinogen, PlateletMapping assay, and novel modified assays using Ecarin and HFXa were prepared. All TEG parameters were recorded. DOAC concentrations were correlated to the parameters with highest response to the DOAC effect. Sensitivity and negative predictive value of the parameter with highest response to DOAC concentration of 50 ng/mL was calculated. None of the conventional TEG assays demonstrated significant response to the effect on apixaban. Using Ecarin, reaction time R was strongly correlated with dabigatran concentrations. Using HFXa assay, R was strongly correlated with rivaroxaban and apixaban concentrations: r = 0.96, 0.84, and 0.86, respectively; p < 0.0001 for all. The R times obtained with the modified assays demonstrated strong sensitivity and negative predictive values for DOAC levels of ≥50 ng/mL. We have demonstrated that TEG®5000 can monitor the DOAC effect on hemostasis when the appropriate activator is used with significant correlation with DOAC concentrations. Larger clinical studies are warranted for correlation of TEG profile and clinical outcomes.

The Choice between Plasma-Based Common Coagulation Tests and Cell-Based Viscoelastic Tests in Monitoring Hemostatic Competence: Not an either-or Proposition

There has been a significant interest in the last decade in the use of viscoelastic tests (VETs) to determine the hemostatic competence of bleeding patients. Previously, common coagulation tests (CCTs) such as the prothrombin time (PT) and partial thromboplastin time (PTT) were used to assist in the guidance of blood component and hemostatic adjunctive therapy for these patients. However, the experience of decades of VET use in liver failure with transplantation, cardiac surgery, and trauma has now spread to obstetrical hemorrhage and congenital and acquired coagulopathies. Since CCTs measure only 5 to 10% of the lifespan of a clot, these assays have been found to be of limited use for acute surgical and medical conditions, whereby rapid results are required. However, there are medical indications for the PT/PTT that cannot be supplanted by VETs. Therefore, the choice of whether to use a CCT or a VET to guide blood component therapy or hemostatic adjunctive therapy may often require consideration of both methodologies. In this review, we provide examples of the relative indications for CCTs and VETs in monitoring hemostatic competence of bleeding patients.

The Applicability of Thromboelastography in Acute Ischemic Stroke: A Literature Review

Acute ischemic stroke (AIS) due to cerebral artery occlusion is often treated by thrombolytics or antithrombotic drugs. Thromboelastography (TEG) is a noninvasive test that provides a dynamic overview of the coagulation process. TEG may help guide thrombolytic and antithrombotic therapy in AIS. This article aims to highlight the potential use of TEG in AIS patients by reviewing available studies. We conducted a literature review, including PubMed and Cochrane library databases. The following keywords were used to find relevant studies: thromboelastography, TEG, acute ischemic stroke, stroke, coagulopathy, antiplatelet, and anticoagulant treatment. We identified 142 papers and after abstract review, we included 24 studies in this report. TEG identified a hypercoagulable state in AIS patients represented by short R, K, and greater α: angle in all papers included. Modification of TEG parameters induced by intravenous thrombolysis was inconsistent but prolonged lysis (increased LY30) and weaker clots (lower maximum amplitude) were most frequent. TEG detected hypo-coagulopathy induced by dual antiplatelet therapy as well as antiplatelet drug resistance, with ticagrelor and aspirin having greater inhibition of platelet activity. A prolonged R-value seems to be the most reliable TEG parameter in detecting the anticoagulant effect of factor Xa inhibitor treatment. TEG might represent a useful point-of-care test for emergency decision-making in AIS patients and a tool for individualized treatment options. This hypothesis needs validation in a large cohort of prospectively studied AIS patients.

The Applicability of Thromboelastography in Acute Ischemic Stroke: A Literature Review

Acute ischemic stroke (AIS) due to cerebral artery occlusion is often treated by thrombolytics or antithrombotic drugs. Thromboelastography (TEG) is a noninvasive test that provides a dynamic overview of the coagulation process. TEG may help guide thrombolytic and antithrombotic therapy in AIS. This article aims to highlight the potential use of TEG in AIS patients by reviewing available studies. We conducted a literature review, including PubMed and Cochrane library databases. The following keywords were used to find relevant studies: thromboelastography, TEG, acute ischemic stroke, stroke, coagulopathy, antiplatelet, and anticoagulant treatment. We identified 142 papers and after abstract review, we included 24 studies in this report. TEG identified a hypercoagulable state in AIS patients represented by short R, K, and greater α: angle in all papers included. Modification of TEG parameters induced by intravenous thrombolysis was inconsistent but prolonged lysis (increased LY30) and weaker clots (lower maximum amplitude) were most frequent. TEG detected hypo-coagulopathy induced by dual antiplatelet therapy as well as antiplatelet drug resistance, with ticagrelor and aspirin having greater inhibition of platelet activity. A prolonged R-value seems to be the most reliable TEG parameter in detecting the anticoagulant effect of factor Xa inhibitor treatment. TEG might represent a useful point-of-care test for emergency decision-making in AIS patients and a tool for individualized treatment options. This hypothesis needs validation in a large cohort of prospectively studied AIS patients.

Viscoelastic Hemostatic Assays for Orthopedic Trauma and Elective Procedures

The application of viscoelastic hemostatic assays (VHAs) (e.g., thromboelastography (TEG) and rotational thromboelastometry (ROTEM)) in orthopedics is in its relative infancy when compared with other surgical fields. Fortunately, several recent studies describe the emerging use of VHAs to quickly and reliably analyze the real-time coagulation and fibrinolytic status in both orthopedic trauma and elective orthopedic surgery. Trauma-induced coagulopathy—a spectrum of abnormal coagulation phenotypes including clotting factor depletion, inadequate thrombin generation, platelet dysfunction, and dysregulated fibrinolysis—remains a potentially fatal complication in severely injured and/or hemorrhaging patients whose timely diagnosis and management are aided by the use of VHAs. Furthermore, VHAs are an invaluable compliment to common coagulation tests by facilitating the detection of hypercoagulable states commonly associated with orthopedic injury and postoperative status. The use of VHAs to identify hypercoagulability allows for an accurate venous thromboembolism (VTE) risk assessment and monitoring of VTE prophylaxis. Until now, the data have been insufficient to permit an individualized approach with regard to dosing and duration for VTE thromboprophylaxis. By incorporating VHAs into routine practice, orthopedic surgeons will be better equipped to diagnose and treat the complete spectrum of coagulation abnormalities faced by orthopedic patients. This work serves as an educational primer and up-to-date review of the current literature on the use of VHAs in orthopedic surgery.

Andexanet alfa after 4-factor PCC administration for intracranial hemorrhage: a case series

The ongoing controversy regarding optimal reversal agent for factor Xa-inhibitors is mainly due to lack of comparative data of andexanet alfa (AA) to 4-factor prothrombin complex concentrate (4F-PCC), institutional formulary restrictions, and navigation of clinical scenarios involving patients clinically worsen despite initial reversal efforts. The combination use of 4F-PCC and AA has not been evaluated in clinical trials and the outcomes of such patients with FXA-inhibitor associated intracranial hemorrhage (ICH) are unknown. A total of five patients, including four outside hospital transfers, received 4F-PCC prior to AA for FXa-inhibitor associated ICH (n = 3 apixaban, n = 2 rivaroxaban; n = 4 ICH, n = 1 TBI). The doses of 4F-PCC ranged from 25 to 60 units/kg and were administered within a range of 1.5-4.2 h prior to AA. One patient required surgical intervention with craniotomy and three patients underwent external ventricular drain placement. Two of the five patients developed an ischemic or thromboembolic complication within one week from 4F-PCC and AA administration. This case series discusses multiple unique patient cases in which 4F-PCC and AA were both administered for FXa-inhibitor associated ICH. The results highlight the potentially increased thrombotic risk associated with combination use. Ongoing post-marketing data collection of real patient case scenarios are essential to the establishment of consensus guidelines on how to prioritize initial reversal efforts and manage these patients during the course of their bleed.

Coagulation status in patients with pulmonary embolism receiving long-term anticoagulant therapy

Aim. To study the blood coagulation status by various laboratory methods in patients after pulmonary embolism (PE) receiving long-term anticoagulant therapy.

Material and methods. The blood of 23 patients with pulmonary embolism, who received long-term anticoagulant therapy, was studied. The study of coagulation profile, D-dimer, thrombodynamics, thromboelastography and thrombin generation test were carried out.

Results. The thrombin generation test shows a significant increase in the time of its formation, while the maximum amount of thrombin formed is half that of the reference values. There is a slightly increased median fibrin clot growth rate in the thrombodynamics test — 30,4 gm/min with a normal coagulation rate of 20-29 gm/min. The result of thromboelastography also reflects the blood hypocoagulation, in terms of R, Angle a and CI.

Conclusion. Integral methods for assessing the thrombotic readiness in combination with a routine coagulation panel demonstrate a complete picture of blood coagulation potential in patients after pulmonary embolism requiring long-term anticoagulant therapy.

Pro-Con Debate: Viscoelastic Hemostatic Assays Should Replace Fixed Ratio Massive Transfusion Protocols in Trauma

Major trauma patients at risk of traumatic coagulopathy are commonly treated with early clotting factor replacement to maintain hemostasis and prevent microvascular bleeding. In the United States, trauma transfusions are often dosed by empiric, low-ratio massive transfusion protocols, which pair plasma and platelets in some ratio relative to the red cells, such as the "1:1:1" combination of 1 units of red cells, 1 unit of plasma, and 1 donor's worth of pooled platelets. Empiric transfusion increases the rate of overtransfusion when unnecessary blood products are administered based on a formula and not on at patient's hemostatic profile. Viscoelastic hemostatic assays (VHAs) are point-of-care hemostatic assays that provided detailed information about abnormal clotting pathways. VHAs are used at many centers to better target hemostatic therapies in trauma. This Pro/Con section will address whether VHA guidance should replace empiric fixed ratio protocols in major trauma.

Evaluation of direct oral anticoagulant use on thromboelastography in an emergency department population

BACKGROUND

Direct oral anticoagulant (DOAC) use presents a challenge to all providers involved in emergency care of patients since widely accepted laboratory tests to assess the level of anticoagulation for such medications are lacking. Viscoelastic tests such as thromboelastography (TEG) tests are increasingly used throughout major trauma centers to help guide resuscitation efforts in patients presenting with trauma and/or hemorrhagic shock.

OBJECTIVE

The primary outcome compared TEG parameters between emergency department trauma patients reporting DOAC therapy and known normal TEG parameter values. The secondary outcome evaluated patients who reported time of last known DOAC dose within a preferred time frame of <12 h for once daily dosing DOAC therapy or < 6 h for twice daily dosing DOAC therapy.

METHODS

This single-center, retrospective cohort study assessed TEG values in patients receiving DOAC therapy and compared these to institution TEG ranges considered normal. TEG values of reaction time (R time), kinetics (K), alpha angle (AA), maximum amplitude (MA), and percent lysis in 30 min (LY30) were collected for patients reporting DOAC therapy.

RESULTS

40 patients were included in this study. 19 patients reported apixaban therapy and 21 reported rivaroxaban therapy. 5 (12.5%) patients had an elevated R time and 1 (2.5%) patient had a reduced MA. All other TEG values did not suggest hypocoagulability. For the secondary outcome assessing patients reporting last known dose within the preferred time frame, only the R time was elevated in 2 (14.3%) patients. Lastly, in a subgroup analysis of patients with elevated low-molecular-weight heparin (LMWH) orAnti- Xa levels, the R time was the only parameter affected in 25% of patients.

CONCLUSION

TEG values were typically not affected by rivaroxaban or apixaban use in an emergency department trauma population suggesting that TEG is not sensitive for Xa inhibitor detection and should not be relied upon for assessing anticoagulation in such settings.

The Role of TEG and ROTEM in Damage Control Resuscitation

ABSTRACT

Trauma-induced coagulopathy is associated with very high mortality, and hemorrhage remains the leading preventable cause of death after injury. Directed methods to combat coagulopathy and attain hemostasis are needed. The available literature regarding viscoelastic testing, including thrombelastography (TEG) and rotational thromboelastometry (ROTEM), was reviewed to provide clinically relevant guidance for emergency resuscitation. These tests predict massive transfusion and developing coagulopathy earlier than conventional coagulation testing, within 15 min using rapid testing. They can guide resuscitation after trauma, as well. TEG and ROTEM direct early transfusion of fresh frozen plasma when clinical gestalt has not activated a massive transfusion protocol. Reaction time and clotting time via these tests can also detect clinically significant levels of direct oral anticoagulants. Slowed clot kinetics suggest the need for transfusion of fibrinogen via concentrates or cryoprecipitate. Lowered clot strength can be corrected with platelets and fibrinogen. Finally, viscoelastic tests identify fibrinolysis, a finding associated with significantly increased mortality yet one that no conventional coagulation test can reliably detect. Using these parameters, guided resuscitation begins within minutes of a patient's arrival. A growing body of evidence suggests this approach may improve survival while reducing volumes of blood products transfused.

Viscoelastic monitoring in trauma resuscitation

BACKGROUND

Traumatic injury results in both physical and physiologic insult. Successful care of the trauma patient depends upon timely correction of both physical and biochemical injury. Trauma-induced coagulopathy is a derangement of hemostasis and thrombosis that develops rapidly and can be fatal if not corrected. Viscoelastic monitoring (VEM) assays have been developed to provide rapid, accurate, and relatively comprehensive depictions of an individual's coagulation profile. VEM are increasingly being integrated into trauma resuscitation guidelines to provide dynamic and individualized guidance to correct coagulopathy.

STUDY DESIGN AND METHODS

We performed a narrative review of the search terms viscoelastic, thromboelastography, thromboelastometry, TEG, ROTEM, trauma, injury, resuscitation, and coagulopathy using PubMed. Particular focus was directed to articles describing algorithms for management of traumatic coagulopathy based on VEM assay parameters.

RESULTS

Our search identified 16 papers with VEM-guided resuscitation strategies in adult patients based on TEG, 12 such protocols in adults based on ROTEM, 1 protocol for children based on TEG, and 2 protocols for children based on ROTEM.

CONCLUSIONS

This review presents evidence to support VEM use to detect traumatic coagulopathy, discusses the role of VEM in trauma resuscitation, provides a summary of proposed treatment algorithms, and discusses pending questions in the field.

Identification of hypercoagulability with thrombelastography in patients with hip fracture receiving thromboprophylaxis

Background:

Venous thromboembolism (VTE) is the second most common complication after hip fracture surgery. We used thrombelastography (TEG), a wholeblood, point-of-care test that can provide an overview of the clotting process, to determine the duration of hypercoagulability after hip fracture surgery.

Methods:

In this prospective study, consecutive patients aged 51 years or more with hip fractures (trochanteric region or neck) amenable to surgical treatment who presented to the emergency department were eligible for enrolment. Thrombelastography, including calculation of the coagulation index (CI) (combination of 4 TEG parameters for an overall assessment of coagulation) was performed daily from admission until 5 days postoperatively, and at 2 and 6 weeks postoperatively. All patients received 28 days of thromboprophylaxis. We used single-sample t tests to compare mean maximal amplitude (MA) values (a measure of clot strength) to the hypercoagulable threshold of greater than 65 mm, a predictor of in-hospital VTE.

Results:

Of the 35 patients enrolled, 11 (31%) were hypercoagulable on admission based on an MA value greater than 65 mm, and 29 (83%) were hypercoagulable based on a CI value greater than 3.0; the corresponding values at 6 weeks were 23 (66%) and 34 (97%). All patients had an MA value greater than 65 mm at 2 weeks. Patients demonstrated normal coagulation on admission (mean MA value 62.2 mm [standard deviation (SD) 6.3 mm], p = 0.01) but became significantly hypercoagulable at 2 weeks (mean 71.6 mm [SD 2.6 mm], p < 0.001). There was a trend toward persistent hypercoagulability at 6 weeks (mean MA value 66.2 mm [SD 3.8 mm], p = 0.06).

Conclusion:

More than 50% of patients remained hypercoagulable 6 weeks after fracture despite thromboprophylaxis. Thrombelastography MA thresholds or a change in MA over time may help predict VTE risk; however, further study is needed.

Viscoelastometry for detecting oral anticoagulants

Background

Determination of anticoagulant therapy is of pronounced interest in emergency situations. However, routine tests do not provide sufficient insight. This study was performed to investigate the impact of anticoagulants on the results of viscoelastometric assays using the ClotPro device.

Methods

This prospective, observational study was conducted in patients receiving dabigatran, factor Xa (FXa)-inhibitors, phenprocoumon, low molecular weight heparin (LMWH) or unfractionated heparin (UFH) (local ethics committee approval number: 17–525-4). Healthy volunteers served as controls. Viscoelastometric assays were performed, including the extrinsic test (EX-test), intrinsic test (IN-test) Russel’s viper venom test (RVV-test), ecarin test (ECA-test), and the tissue plasminogen activator test (TPA-test).

Results

70 patients and 10 healthy volunteers were recruited. Clotting time in the EX-test (CT_EX-test) was significantly prolonged versus controls by dabigatran, FXa inhibitors and phenprocoumon. CT_IN-test was prolonged by dabigatran, FXa inhibitors and UFH. Dabigatran, FXa inhibitors and UFH significantly prolonged CT_RVV-test in comparison with controls (median 200, 207 and 289 vs 63 s, respectively; all p < 0.0005). Only dabigatran elicited a significant increase in CT_ECA-test compared to controls (median 307 vs 73 s; p < 0.0001). CT_ECA-test correlated strongly with dabigatran plasma concentration (measured by anti-IIa activity; r = 0.9970; p < 0.0001) and provided 100% sensitivity and 100% specificity for detecting dabigatran. Plasma concentrations (anti-XA activity) of FXa inhibitors correlated with CT_RVV-test (r = 0.7998; p < 0.0001), and CT_RVV-test provided 83% sensitivity and 64% specificity for detecting FXa inhibitors.

Conclusions

In emergency situations, ClotPro viscoelastometric assessment of whole-blood samples may help towards determining the presence and type of anticoagulant class that a patient is taking.

Trial registration

German clinical trials database ID: DRKS00015302.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-021-00267-w.

High-Dose Dabigatran Is an Effective Anticoagulant for Simulated Cardiopulmonary Bypass Using Human Blood

BACKGROUND

Currently no ideal alternative exists for heparin for cardiopulmonary bypass (CPB). Dabigatran is a direct thrombin inhibitor for which a reversal agent exists. The primary end point of the study was to explore whether Dabigatran was an effective anticoagulant for 120 minutes of simulated CPB.

METHODS

The study was designed in 2 sequential steps. Throughout, human blood from healthy donors was used for each experimental step. Initially, increasing concentrations of Dabigatran were added to aliquots of fresh whole blood, and the anticoagulant effect measured using kaolin/tissue factor-activated thromboelastography (rapidTEG). The dynamics of all thromboelastography (TEG) measurements were studied with repeated measures analysis of variance (ANOVA). Based on these data, aliquots of blood were treated with high-concentration Dabigatran and placed in a Chandler loop as a simple ex vivo bypass model to assess whether Dabigatran had sufficient anticoagulant effects to maintain blood fluidity for 2 hours of continuous contact with the artificial surface of the PVC tubing. Idarucizumab, humanized monoclonal antibody fragment, was used to verify the reversibility of Dabigatran effects. Finally, 3 doses of Dabigatran were tested in a simulated CPB setup using a heart-lung machine and a commercially available bypass circuit with an arteriovenous (A-V) loop. The primary outcome was the successful completion of 120 minutes of simulated CPB with dabigatran anticoagulation, defined as lack of visible thrombus. Thromboelastographic reaction (R) time was measured repeatedly in each bypass simulation, and the circuits were continuously observed for clot. Scanning Electron Microscopy (SEM) was used to visualize fibrin formation in the filters meshes during CPB.

RESULTS

In in vitro blood samples, Dabigatran prolonged R time and reduced the dynamics of clot propagation (as measured by speed of clot formation [Angle], maximum rate of thrombus generation [MRTG], and time to maximum rate of thrombus generation [TMRTG]) in a dose-dependent manner. In the Chandler Loop, high doses of Dabigatran prevented clot formation for 120 minutes, but only at doses higher than expected. Idarucizumab decreased R time and reversed anticoagulation in both in vitro and Chandler Loops settings. In the A-V loop bypass simulation, Dabigatran prevented gross thrombus generation for 120 minutes of simulated CPB.

CONCLUSIONS

Using sequential experimental approaches, we showed that direct thrombin inhibitor Dabigatran in high doses maintained anticoagulation of blood for simulated CPB. Idarucizumab reduced time for clot formation reversing the anticoagulation action of Dabigatran.

Coagulation Effect of Sugammadex as Determined by Thromboelastography in a Randomized Controlled Study of Surgical Patients

Introduction: Sugammadex has been shown to be associated with prolongation of prothrombin time and activated partial thromboplastin time. However, it is not known whether it could be associated with enhancing postoperative hypocoagulation. The objective of this study was to analyze the effect of 4 mg/kg of sugammadex on thromboelastography (TEG) parameters in surgical patients. Methods: After Institutional Review Board approval, a prospective double-blinded randomized controlled study was conducted between September 2016 and April 2017. Sixty adult patients scheduled for laparoscopic abdominal surgery were randomly allocated to receive either sugammadex 4 mg/kg (sugammadex group) or pyridostigmine 0.15 mg/kg in combination with glycopyrrolate 0.4 mg (control group) to reverse rocuronium-induced neuromuscular blockade at the completion of surgery. Blood samples were collected three time points; After the final suture of surgery (baseline) (T1), and at 10 min (T2) and 1 h (T3) after administration of the study drug. Whole blood was analyzed by TEG using TEG 5000 (Hemonetics Corp, Braintree, MA, USA). The primary endpoints were comparison of coagulation time (K, time to 20 mm clot amplitude), R (reaction time), alpha angle, and maximal amplitude (MA) between two groups. Results: Coagulation time was significantly prolonged in sugammadex group after 10 min of the study drug administration compared to control group (mean value 1.3 ± 0.4 vs. 1.5 ± 0.4, P = 0.03). However, R, alpha angle and MA value were not different between two groups. Conclusions: Sugammadex 4 mg/kg showed an increase in coagulation time in surgical patients. Physician should aware the potential enhancement of hypocoagulation by sugammadex in the setting of high risk of postoperative bleeding.

Use of direct-acting oral anticoagulants in solid organ transplantation: A systematic review

The use of direct-acting oral anticoagulants (DOACs) has increased secondary to the mounting evidence for comparable efficacy and potentially superior safety to vitamin K antagonists (VKAs) in the general population. However, insufficient data regarding DOAC use in solid organ transplant (SOT) recipients and numerous pharmacokinetic and pharmacodynamic considerations limit their use in this highly selected patient population. A systematic review of recent clinical evidence on the safety and efficacy of DOACs compared to VKAs in SOT recipients was conducted. Additional considerations including transplant-specific strategies for DOAC reversal and common pharmacokinetic/pharmacodynamic concerns were also reviewed. Although current evidence is limited to single-center retrospective analyses, DOACs, especially apixaban, appear to be a safe and effective alternative to VKAs for SOT recipients with stable graft function and without drug-drug interactions. Reliable data on DOAC reversal at the time of transplant surgery are lacking, and clinicians should consider idarucizumab, andexanet alfa, and other non-specific reversal agents on an individual patient basis. There is no evidence supporting deviations from the Food and Drug Administration labeling recommendations for DOAC dosing in the setting of drug-drug interactions, obesity, and renal function, especially in patients on hemodialysis.

Apixaban enhances endogenous fibrinolysis in patients with atrial fibrillation

Aims

Approximately 20% of ischaemic stroke patients exhibit spontaneous arterial recanalization, attributable to endogenous fibrinolysis, which strongly relates to improved functional outcome. The impact of oral anticoagulants on endogenous fibrinolysis is unknown. Our aim was to test the hypothesis that apixaban enhances endogenous fibrinolysis in non-valvular atrial fibrillation (NVAF).

Methods and results

In a prospective cross-sectional analysis, we compared endogenous fibrinolysis in NVAF patients (n = 180) taking aspirin, warfarin, or apixaban. In a prospective longitudinal study, patients were tested before and after apixaban (n = 80). Endogenous fibrinolysis was assessed using the Global Thrombosis Test (GTT) and thromboelastography (TEG). Endogenous fibrinolysis [measured by GTT lysis time (LT)] was shorter on apixaban compared with warfarin or aspirin [median 1850 (IQR 1591–2300) vs. 2758 (2014–3502) vs. 2135 (1752–2463) s, P < 0.0001]. Among TEG indices, a small but significant difference in clot lysis time (CLT) was observed [apixaban 60.0 (45.0–61.0) vs. warfarin 61.0 (57.0–62.0) vs. aspirin 61.0 (59.0–61.0) min, P = 0.036]. Apixaban improved endogenous fibrinolysis measured using the GTT [LT pre-treatment 2204 (1779–2738) vs. on-treatment 1882 (1607–2374) s, P = 0.0003], but not by using TEG. Change in LT (ΔLT) with apixaban correlated with baseline LT (r = 0.77, P < 0.0001). There was weak correlation between ΔLT and ΔCLT in response to apixaban (r = 0.28, P = 0.02) and between on-apixaban LT and CLT (r = 0.25, P = 0.022).

Conclusion

Apixaban enhances endogenous fibrinolysis, with maximal effect in those with impaired fibrinolysis pre-treatment. Apixaban-treated patients exhibit more favourable fibrinolysis profiles than those taking warfarin or aspirin. Whether apixaban may confer additional thrombotic risk reduction in NVAF patients with impaired fibrinolysis, compared to warfarin, merits further study.

Relationship of Edoxaban Plasma Concentration and Blood Coagulation in Healthy Volunteers Using Standard Laboratory Tests and Viscoelastic Analysis

The capability of viscoelastic measurement parameters to screen anticoagulation activity of edoxaban in relation to its plasma concentrations was evaluated in 15 healthy male volunteers. Blood samples were drawn before the oral administration of edoxaban 60 mg and 2, 4, 6, 8, and 24 hours after administration. At each time, standard coagulation tests were performed, blood viscoelastic properties were measured with a thromboelastometry device ROTEM delta analyzer (Instrumentation Laboratory, Werfen, Barcelona, Spain), and edoxaban plasma concentrations were measured. Our primary interest was the possible correlation between edoxaban plasma concentrations and values for ROTEM ExTEM, and FibTEM. We also studied the correlation of edoxaban plasma concentrations with the results of standard coagulation tests. We saw the effect of a single dose of edoxaban most clearly in clotting time (CT) of ROTEM ExTEM and FibTEM. Changes in these parameters correlated significantly with edoxaban plasma concentrations up to 6 hours from the ingestion of the drug. Activated partial thromboplastin time, prothrombin time, and anti-factor Xa were also affected. Peak changes were observed 2 and 4 hours after administration of edoxaban. The changes were mostly reversed after 8 hours. In conclusion, ROTEM CT correlates significantly with edoxaban plasma concentrations and can be used to estimate the effect of edoxaban. ROTEM should be considered as part of the assessment of coagulation, with the big advantage of being readily available on site.

Point-of-Care Diagnostics in Coagulation Management

This review provides a comprehensive and up-to-date overview of point-of-care (POC) devices most commonly used for coagulation analyses in the acute settings. Fast and reliable assessment of hemostasis is essential for the management of trauma and other bleeding patients. Routine coagulation assays are not designed to visualize the process of clot formation, and their results are obtained only after 30-90 m due to the requirements of sample preparation and the analytical process. POC devices such as viscoelastic coagulation tests, platelet function tests, blood gas analysis and other coagulometers provide new options for the assessment of hemostasis, and are important tools for an individualized, goal-directed, and factor-based substitution therapy. We give a detailed overview of the related tests, their characteristics and clinical implications. This review emphasizes the evident advantages of the speed and predictive power of POC clot measurement in the context of a goal-directed and algorithm-based therapy to improve the patient's outcome. Interpretation of viscoelastic tests is facilitated by a new visualization technology.

Diagnostic performance of coagulation indices for direct oral anticoagulant concentration

INTRODUCTION

Different coagulation indices for direct oral anticoagulants (DOACs) exist in clinical practice, but limited data are available for the diagnostic power of these indices. This review and meta-analysis aims to explore the diagnostic value of coagulation indices for DOACs.

MATERIALS AND METHODS

PubMed, Web of Science, EMBASE, Clinical Trials.gov, and the Cochrane Library were searched from inception of each database to 15 February 2020. Studies reporting a relationship between coagulation indices and the gold standard (liquid chromatography/tandem mass spectrometry) were included in the analysis.

RESULTS

Sixteen articles from 9169 citations evaluating the performance of coagulation indices were included in this review. A total of 236, 273, 273 rivaroxaban samples were included to assess the diagnostic power of anti-Xa activity (AXA), prothrombin time (PT), combined PT and activated partial thromboplastin time, respectively. A total of 268 dabigatran samples were included to assess the diagnostic performance of diluted thromboplastin time (dTT). AXA calibrated by rivaroxaban showed a sensitivity of 0.98 (95% confidence interval (CI): 0.91-0.99) and a specificity of 0.98 (95% CI: 0.94-0.99) at the threshold of 30 ng/mL. For dabigatran, the combined sensitivity of dTT was 0.76 (95% CI: 0.66-0.84) and combined specificity was 0.97 (95% CI: 0.92-0.99).

CONCLUSIONS

DOAC-specific calibrated AXA was a good index to indicate concentration for rivaroxaban and apixaban. More studies on edoxaban and betrixaban are in need. Diluted TT, thrombin inhibitor assay, and ecarin-based assays were potential to measure dabigatran concentration. Due to the limited data, results should be validated in the future.

[TEG-guided treatment of a dabigatran overdose in a patient with acute kidney failure]

This article presents the case of a multimorbid male patient with an accidental dabigatran overdose caused by kidney failure in the context of an acute intestinal disorder. After effective initial antagonizing of the dabigatran effect using idarucizumab a dabigatran rebound was detected caused by a single hemodialysis leading to a severe intrapulmonary hemorrhage. As dabigatran plasma level testing was not available and conventional coagulation analysis was out of interpretable range due to the impact of dabigatran, continuous thrombelastography (TEG) was used to detect the effect of dabigatran and monitor the treatment results. The most significant parameter used in the kaolin activated clotting time was the R‑time parameter, which was massively prolonged by the interrupted coagulation cascade.

Tracing the Lines: A Review of Viscoelastography for Emergency Medicine Clinicians

BACKGROUND

Viscoelastography (VE) is an established method to identify coagulopathies in various disease processes. Clinical decisions can be made with real-time tracings and quantitative values at the bedside. Thromboelastography (TEG®) and rotational thromboelastometry (ROTEM®) have been utilized in several disease states with clinical varying success.

OBJECTIVES

This review will summarize the literature and provide recommendations pertaining to major disease processes where VE may be beneficial, including trauma, anticoagulation reversal, liver disease, acute ischemic stroke, and acquired brain injuries.

DISCUSSION

VE has a role in many emergency medicine patients encountered by clinicians. Reduced mortality, decreased blood product utilization, and prognostication ability makes VE an intriguing tool that can be utilized by providers to improve patient care.

CONCLUSION

This review serves as a way for emergency medicine clinicians to utilize VE in their practice and provides an insightful literature overview.

Detecting direct oral anticoagulants in trauma patients using liquid chromatography-mass spectrometry: A novel approach to medication reconciliation

BACKGROUND

Accurate medication reconciliation in trauma patients is essential but difficult. Currently, there is no established clinical method of detecting direct oral anticoagulants (DOACs) in trauma patients. We hypothesized that a liquid chromatography-mass spectrometry (LCMS)-based assay can be used to accurately detect DOACs in trauma patients upon hospital arrival.

METHODS

Plasma samples were collected from 356 patients who provided informed consent including 10 healthy controls, 19 known positive or negative controls, and 327 trauma patients older than 65 years who were evaluated at our large, urban level 1 trauma center. The assay methodology was developed in healthy and known controls to detect apixaban, rivaroxaban, and dabigatran using LCMS and then applied to 327 samples from trauma patients. Standard medication reconciliation processes in the electronic medical record documenting DOAC usage were compared with LCMS results to determine overall accuracy, sensitivity, specificity, and positive and negative predictive values (PPV, NPV) of the assay.

RESULTS

Of 356 patients, 39 (10.96%) were on DOACs: 21 were on apixaban, 14 on rivaroxaban, and 4 on dabigatran. The overall accuracy of the assay for detecting any DOAC was 98.60%, with a sensitivity of 94.87% and specificity of 99.05% (PPV, 92.50%; NPV, 99.37%). The assay detected apixaban with a sensitivity of 90.48% and specificity of 99.10% (PPV, 86.36%; NPV 99.40%). There were three false-positive results and two false-negative LCMS results for apixaban. Dabigatran and rivaroxaban were detected with 100% sensitivity and specificity.

CONCLUSION

This LCMS-based assay was highly accurate in detecting DOACs in trauma patients. Further studies need to confirm the clinical efficacy of this LCMS assay and its value for medication reconciliation in trauma patients.

LEVEL OF EVIDENCE

Diagnostic Test, level III.

Viscoelastic Hemostatic Assays: Moving from the Laboratory to the Site of Care-A Review of Established and Emerging Technologies

Viscoelastic-based techniques to evaluate whole blood hemostasis have advanced substantially since they were first developed over 70 years ago but are still based upon the techniques first described by Dr. Hellmut Hartert in 1948. Today, the use of thromboelastography, the method of testing viscoelastic properties of blood coagulation, has moved out of the research laboratory and is now more widespread, used commonly during surgery, in emergency departments, intensive care units, and in labor wards. Thromboelastography is currently a rapidly growing field of technological advancement and is attracting significant investment. This review will first describe the history of the viscoelastic testing and the established first-generation devices, which were developed for use within the laboratory. This review will then describe the next-generation hemostasis monitoring devices, which were developed for use at the site of care for an expanding range of clinical applications. This review will then move on to experimental technologies, which promise to make viscoelastic testing more readily available in a wider range of clinical environments in the endeavor to improve patient care.

Correlation of Thromboelastography with Apparent Rivaroxaban Concentration: Has Point-of-Care Testing Improved?

BACKGROUND

Concern remains over reliable point-of-care testing to guide reversal of rivaroxaban, a commonly used factor Xa inhibitor, in high-acuity settings. Thromboelastography (TEG), a point-of-care viscoelastic assay, may have the ability to detect the anticoagulant effect of rivaroxaban. The authors ascertained the association of apparent rivaroxaban concentration with thromboelastography reaction time, i.e., time elapsed from blood sample placement in analyzer until beginning of clot formation, as measured using TEG and TEG6S instruments (Haemonetics Corporation, USA), hypothesizing that reaction time would correlate to degree of functional factor Xa impairment.

METHODS

The authors prospectively performed a diagnostic accuracy study comparing coagulation assays to apparent (i.e., indirectly assessed) rivaroxaban concentration in trauma patients with and without preinjury rivaroxaban presenting to a single center between April 2016 and July 2018. Blood samples at admission and after reversal or 24 h postadmission underwent TEG, TEG6S, thrombin generation assay, anti-factor Xa chromogenic assay, prothrombin time (PT), and ecarin chromogenic assay testing. The authors determined correlation of kaolin TEG, TEG6S, and prothrombin time to apparent rivaroxaban concentration. Receiver operating characteristic curve compared capacity to distinguish therapeutic rivaroxaban concentration (i.e., greater than or equal to 50 ng/ml) from nontherapeutic concentrations.

RESULTS

Eighty rivaroxaban patients were compared to 20 controls. Significant strong correlations existed between rivaroxaban concentration and TEG reaction time (ρ = 0.67; P < 0.001), TEG6S reaction time (ρ = 0.68; P < 0.001), and prothrombin time (ρ = 0.73; P < 0.001), however reaction time remained within the defined normal range for the assay. Rivaroxaban concentration demonstrated strong but not significant association with coagulation assays postreversal (n = 9; TEG reaction time ρ = 0.62; P = 0.101; TEG6S reaction time ρ = 0.57; P = 0.112) and small nonsignificant association for controls (TEG reaction time: ρ = -0.04; P = 0.845; TEG6S reaction time: ρ = -0.09; P = 0.667; PT-neoplastine: ρ = 0.19; P = 0.301). Rivaroxaban concentration (area under the curve, 0.91) and TEG6S reaction time (area under the curve, 0.84) best predicted therapeutic rivaroxaban concentration and exhibited similar receiver operating characteristic curves (P = 0.180).

CONCLUSIONS

Although TEG6S demonstrates significant strong correlation with rivaroxaban concentration, values within normal range limit clinical utility rendering rivaroxaban concentration the gold standard in measuring anticoagulant effect.

Factor Xa Inhibitory Profile of Apixaban, Betrixaban, Edoxaban, and Rivaroxaban Does Not Fully Reflect Their Biologic Spectrum

The currently available oral anti-Xa agents are claimed to produce their anticoagulant and antithrombotic effects solely by the inhibition of factor Xa. This study profiled various anti-Xa drugs in routinely used laboratory assays to demonstrate that their effects are not solely related to the anti-Xa activities. Apixaban, betrixaban, edoxaban, and rivaroxaban were obtained commercially. Native and citrated whole blood was used for the activated clotting time (ACT) and thromboelastography (TEG). Citrated plasma was used for monitoring the prothrombin time (PT), activated partial thromboplastin time (aPTT), Heptest, and prothrombinase-induced clotting time (PiCT) tests. An amidolytic method was used for the determination of anti-Xa effects. Thrombin-induced fibrinokinetics was monitored optically. Thrombin generation studies were carried out using the calibrated automated thrombogram. All of the anti-Xa agents produced concentration- and assay-dependent effects. In the ACT at 2.5 μg/mL and TEG at 1.0 μg/mL, edoxaban exhibited the strongest anticoagulation effect. In the PiCT, PT, and aPTT assay at 1 μg/mL, edoxaban showed stronger effects than other agents. The half maximal inhibitory concentration of these agents for the inhibition of factor Xa ranged from 340 to >1000 ng/mL. In the thrombin generation inhibition assay, apixaban showed the strongest activity. In the fibrinokinetics, different anti-Xa agents produced varying degrees of inhibition. These results demonstrate that the measured anti-Xa activity alone does not fully reflect the overall biologic spectrum of these agents.

Perioperative Management of Patients Receiving New Anticoagulants

There is an increased use of oral anticoagulants for the prevention of venous and arterial thrombosis. Vitamin-K antagonists have been used for decades as the main oral anticoagulants but they have the draback a complex therapeutic management, slow onset of action and by a different oral intake caused by dietary vitamin K intake. New non-vitamin K antagonist oral anticoagulants (NOACs) have been developed to overcome the limitations of warfarin. Their management is easier as it requires a fixed daily dose without coagulation monitoring. Although their therapeutic profile is safe, proper attention should be paid in case of unexpected need for the reversal of their coagulation effect and in case a patient needs to have a scheduled surgery. For non-acute cardiac surgery, discontinuation of NOACs should start at least 48 hours prior surgery. Intracranial bleedings associated with NOACs are less dangerous comparing to those warfarin-induced. NOACs need to be stopped ≥24 hours in case of elective surgery for low bleeding-risk procedures and ≥48 hours for high bleeding-risk surgery in patients with normal renal function and 72 hours in case of reduced CrCl < 80. The therapy with NOACs should be resumed from 48 to 72 hours after the procedure depending on the perceived bleeding, type of surgery and thrombotic risks. There are some available NOAC reversal agents acting within 5 to 20 minutes. In case of lack of reversal agent, adequate diuresis, renal replacement therapy and activated charcoal in case of recent ingestion should be considered.

The Utility of Thromboelastography to Guide Blood Product Transfusion

OBJECTIVES

To provide an overview of the clot viscoelastic testing technology and to describe its utility in guiding blood product transfusions.

METHODS

A case scenario will be discussed as well as interpretation of thromboelastography (TEG) tracings. In addition, literature examining the utility of viscoelastic testing in guiding patient management and blood product transfusions will be reviewed.

RESULTS

TEG/rotational thromboelastometry (ROTEM) is useful in evaluating clot kinetics in trauma and acutely bleeding patients. TEG/ROTEM parameters are reflective of values measured using standard coagulation assays; however, TEG/ROTEM parameters are more rapidly available and more costly. TEG and ROTEM are used in three main settings: cardiac surgery, liver transplantation, and trauma to assess global hemostasis and administration of blood products.

CONCLUSIONS

TEG/ROTEM can be helpful in guiding resuscitation and blood product transfusion. Several studies have demonstrated a reduction in transfusion of blood components with TEG/ROTEM; however, other studies have suggested that TEG/ROTEM is not clinically effective in guiding transfusion.

A New Test for the Detection of Direct Oral Anticoagulants (Rivaroxaban and Apixaban) in the Emergency Room Setting

Determining whether a patient has taken a direct oral anticoagulant (DOAC) is critical during the periprocedural and preoperative period in the emergency department. However, the inaccessibility of complete medical records, along with the generally inconsistent sensitivity of conventional coagulation tests to these drugs, complicates clinical decision making and puts patients at risk of uncontrollable bleeding. In this study, we evaluate the utility of inhibitor-II-X (i-II-X), a novel, microfluidics-based diagnostic assay for the detection and identification of Factor Xa inhibitors (FXa-Is) in an acute care setting.

DESIGN

First-in-human, 91-patient, single-center retrospective pilot study.

SETTING

Emergency room.

PATIENTS

Adult patients admitted into the emergency department, which received any clinician-ordered coagulation test requiring a 3.2% buffered sodium citrate blood collection tube.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Plasma samples from patients admitted to the emergency department were screened for the use of FXa-Is, including apixaban and rivaroxaban, within the past 24 hours using our new i-II-X microfluidic test. i-II-X results were then compared with results from conventional coagulation tests, including prothrombin time (PT) and international normalized ratio (INR), which were ordered by treating clinicians, and an anti-Xa assay for rivaroxaban. The i-II-X test detected DOACs in samples collected from the emergency department with 95.20% sensitivity and 100.00% specificity. Unlike PT and INR, i-II-X reliably identified patients who had prolonged clotting times secondary to the presence of a FXa-I.

CONCLUSIONS

The i-II-X test overcomes the limitations of currently available coagulation tests and could be a useful tool by which to routinely screen patients for DOACs in emergency and critical care settings. Our new diagnostic approach is particularly relevant in clinical situations where medical records may be unavailable, or where precautions need to be taken prior to invasive interventions, such as specific reversal agent administration.

Thromboelastography for the Orthopaedic Surgeon

Evaluation of coagulation is vital in the care of the orthopaedic patients, particularly in the subspecialties of trauma, spine, arthroplasty, and revision surgery resulting from blood loss and coagulopathies. Although conventional tests (prothrombin time/international normalized ratio, activated partial thromboplastin time, platelet count, and fibrinogen) are most commonly used, others like thromboelastography (TEG) are also available to the orthopaedic surgeons. TEG is a blood test developed in the 1950s, which provides a snapshot of a patient's coagulation profile by evaluating clot formation and lysis. Recently, TEG has been used to assess traumatic coagulopathy. The coagulation parameters measured by the TEG are reaction time (R-time), time to reach a certain clot strength (K-value), speed of fibrin build up (α-angle), maximum clot amplitude, and percentage decrease of clot in 30 minutes (LY30). Using these values, traumatologists have developed a better, faster, and more accurate overview of a patient's resuscitation and more successfully direct blood product use. However, many orthopaedic surgeons-despite performing surgical procedures that risk notable blood loss and postoperative clotting complications-are unaware of the existence of the TEG blood test and the critical information it provides. Increasing awareness of the TEG among orthopaedic surgeons could have a notable effect on numerous aspects of musculoskeletal care.

Reversing anticoagulation in the hemorrhaging patient

PURPOSE OF REVIEW

Anticoagulants in general, but especially the relatively new direct oral anticoagulants and platelet inhibitors, pose a great challenge for physicians in the hemorrhaging patient. The aim of the present review is to provide an overview on recent studies dealing with the reversal of anticoagulation in the hemorrhaging patient and to describe our therapeutic emergency strategy for those patients.

RECENT FINDINGS

A specific antidote for dabigatran is already on the market and antidotes for the direct and indirect factor Xa inhibitors are in development. Moreover, bleeding under platelet inhibitors remains critical with very little evidence on effective reversal strategies.

SUMMARY

To reverse anticoagulation in the hemorrhaging patient, specific antidotes should be the first option if available, followed by four-factor prothrombin complex concentrate (PCC), activated PCC and recombinant activated factor seven as the emergency strategy. Fibrinogen concentrate, antifibrinolytics and oral charcoal, respectively, can be considered as an additional measure. Massive blood loss and thrombocytopenia should be treated independently according to the respective, local guidelines for (massive) transfusion of blood and blood products.

In vitro effects of a kaolin-coated hemostatic dressing on anticoagulated blood

BACKGROUND

The use of kaolin-coated dressings has become common and have efficacy in normal patients, but their increased use will inevitably include use on bleeding patients taking anticoagulants. We hypothesize that kaolin coating material (KCM) will improve clotting regardless of anticoagulation medication.

METHODS

A prospective study was performed on blood from patients who were on a vitamin K antagonist (VKA), unfractionated heparin (UH), an antiplatelet (AP) agent, a Xa inhibitor (Xa), or a direct thrombin inhibitor (DTI). None were on more than one type of anticoagulation medication. Viscoelastic testing was performed with and without KCM. All p values were adjusted for multiple comparisons.

RESULTS

The addition of KCM significantly decreased the time for initial clot formation (CT) in all groups. The mean CT for controls was decreased from 692 to 190.8 s (p < 0.0001). KCM decreased the initial clot formation time by about 1.5 times in those on DTI (p = 0.043) and 2.5 times in those taking AP medication (p < 0.001). The most profound effect was seen in those on UH (no KCM 1,602 s vs. KCM 440 s; p < 0.001), VKA (no KCM 1,152 s vs. 232 s; p < 0.01), and Xa (no KCM 1,342 s vs. 287 s; p < 0.001). Analysis of other clot formation parameters revealed that KCM significantly improved the clot formation kinetics (CFT) only in patients taking Xa (p = 0.03). KCM improved maximum clot strength in patients on Xa inhibitors (p = 0.05). Patients on UH had a larger effect size with an increase in clot strength from 24.35 mm to 43.35 mm whereas those on Xa had an increase of 38.7 mm to 49.85 mm.

CONCLUSION

In this in vitro analysis, the addition of KCM to the blood of patients taking any of these anticoagulation medications significantly improved the time to initial clot formation, indicating that kaolin-based hemostatic dressings will be effective in initiating clot formation in patients on anticoagulants.

LEVEL OF EVIDENCE

Therapeutic, level IV.

Diagnostic accuracy of thromboelastometry and its correlation with the HPLC-MS/MS quantification test

The aim of the study was to evaluate the diagnostic accuracy of thromboelastometry for assessing rivaroxaban concentrations. The accuracy of thromboelastometry was compared with the high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method, which is the gold standard for drug plasma monitoring (the reference standard). Forty-six clinically stable patients were treated with 10, 15, or 20 mg of rivaroxaban once daily (OD group) or 15 mg twice a day (BID group) (no particular indication for treatment). Patient samples were collected 2 h after the use of the medication (peak) and 2 h before the next dose (trough). The rivaroxaban plasma concentrations were determined via HPLC-MS/MS, and thromboelastometry was performed using a ROTEM® delta analyzer. There were significant prolongations in clotting time (CT) for the 10, 15, and 20 mg of rivaroxaban treatments in the OD groups. In the 15 mg BID group, the responses at the peak and trough times were similar. At the peak times, there was a positive correlation between the plasma concentration of rivaroxaban and CT (Spearman correlation rho=0.788, P<0.001) and clot formation time (rho=0.784, P<0.001), and a negative correlation for alpha angle (rho=−0.771, P<0.001), amplitude after 5 min (rho=−0.763, P<0.001), and amplitude after 10 min (rho=−0.680, P<0.001). The CT presented higher specificity and sensitivity using the cut-off determined by the receiver characteristics curve. ROTEM has potential as screening tool to measure possible bleeding risk associated with rivaroxaban plasma levels.