Impact of four direct oral anticoagulants on rotational thromboelastometry (ROTEM)

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.

Clinical guideline on reversal of direct oral anticoagulants in patients with life threatening bleeding

BACKGROUND

Anticoagulation is essential for the treatment and prevention of thromboembolic events. Current guidelines recommend direct oral anticoagulants (DOACs) over vitamin K antagonists in DOAC-eligible patients. The major complication of anticoagulation is serious or life-threatening haemorrhage, which may necessitate prompt haemostatic intervention. Reversal of DOACs may also be required for patients in need of urgent invasive procedures. This guideline from the European Society of Anaesthesiology and Intensive Care (ESAIC) aims to provide evidence-based recommendations and suggestions on how to manage patients on DOACs undergoing urgent or emergency procedures including the treatment of DOAC-induced bleeding.

DESIGN

A systematic literature search was performed, examining four drug comparators (dabigatran, rivaroxaban, apixaban, edoxaban) and clinical scenarios ranging from planned to emergency surgery with the outcomes of mortality, haematoma growth and thromboembolic complications. The GRADE (Grading of Recommendations, Assessment, Development and Evaluation) methodology was used to assess the methodological quality of the included studies. Consensus on the wording of the recommendations was achieved by a Delphi process.

RESULTS

So far, no results from prospective randomised trials comparing two active comparators (e.g. a direct reversal agent and an unspecific haemostatic agent such as prothrombin complex concentrate: PCC) have been published yet and the majority of publications were uncontrolled and observational studies. Thus, the certainty of evidence was assessed to be either low or very low (GRADE C). Thirty-five recommendations and clinical practice statements were developed. During the Delphi process, strong consensus (>90% agreement) was achieved in 97.1% of recommendations and consensus (75 to 90% agreement) in 2.9%.

DISCUSSION

DOAC-specific coagulation monitoring may help in patients at risk for elevated DOAC levels, whereas global coagulation tests are not recommended to exclude clinically relevant DOAC levels. In urgent clinical situations, haemostatic treatment using either the direct reversal or nonspecific haemostatic agents should be started without waiting for DOAC level monitoring. DOAC levels above 50 ng ml-1 may be considered clinically relevant necessitating haemostatic treatment before urgent or emergency procedures. Before cardiac surgery under activated factor Xa (FXa) inhibitors, the use of andexanet alfa is not recommended because of inhibition of unfractionated heparin, which is needed for extracorporeal circulation. In the situation of DOAC overdose without bleeding, no haemostatic intervention is suggested, instead measures to eliminate the DOACs should be taken. Due to the lack of published results from comparative prospective, randomised studies, the superiority of reversal treatment strategy vs. a nonspecific haemostatic treatment is unclear for most urgent and emergency procedures and bleeding. Due to the paucity of clinical data, no recommendations for the use of recombinant activated factor VII as a nonspecific haemostatic agent can be given.

CONCLUSION

In the clinical scenarios of DOAC intake before urgent procedures and DOAC-induced bleeding, practitioners should evaluate the risk of bleeding of the procedure and the severity of the DOAC-induced bleeding before initiating treatment. Optimal reversal strategy remains to be determined in future trials for most clinical settings.

Three cases of neutralization of factor Xa inhibitors with andexanet alfa under rotational thromboelastography monitoring

Background

Factor Xa inhibitors are direct oral anticoagulants that are extremely useful in clinical applications, safe, and do not require dose adjustment. It is desirable to be able to monitor their effects in the event of hemorrhagic complications requiring neutralization. However, it is difficult to monitor their activity and neutralization using conventional coagulation tests.

Case Presentation

We report three patients taking factor Xa inhibitors who underwent rotational thromboelastography (ROTEM) monitoring before and after neutralization with andexanet alfa. All three patients had hemorrhagic complications that required neutralization of their factor Xa inhibitors using andexanet alfa. One ROTEM parameter, the EXTEM clotting time (EXTEM-CT), was immediately shortened after andexanet alfa bolus administration, without subsequent extension of the EXTEM-CT assessed 4 h after the bolus dose.

Conclusion

ROTEM parameters, particularly EXTEM-CT, might be useful for monitoring neutralization of factor Xa inhibitors.

Dose-Related Effectiveness of Andexanet Alfa for Reversal of Apixaban Anticoagulation in a Porcine Polytrauma Model

BACKGROUND

 Andexanet alfa (andexanet) is a reversal agent for use in patients with life-threatening or uncontrolled bleeding treated with oral factor Xa (FXa) inhibitors. There are limited data on the dose-response relationship of andexanet and FXa inhibitor-related bleeding.

OBJECTIVE

 The aim of this study was to assess the dose-related effectiveness of andexanet in reducing blood loss, improving survival, and reversing apixaban anticoagulation in a porcine polytrauma model.

METHODS

 Apixaban was given orally to 40 male pigs for 3 days at a dose of 20 mg/d. On day 3, following bilateral femur fractures and blunt liver injury, animals (n = 8/group) received andexanet (250-mg bolus, 250-mg bolus + 300-mg 2-hour infusion, 500-mg bolus, or 500-mg bolus + 600-mg 2-hour infusion) or vehicle (control). Total blood loss was the primary endpoint. Coagulation parameters were assessed for 300 minutes or until death. Data were analyzed with a mixed-model analysis of variance.

RESULTS

 Administration of 250-mg bolus + 300-mg infusion, andexanet 500-mg bolus, and 500-mg bolus + 600-mg infusion significantly decreased total blood loss by 37, 58, and 61%, respectively (all p < 0.0001), with 100% survival. Andexanet 250-mg bolus was ineffective in reducing total blood loss (6%) and mortality (63% survival) versus controls. Andexanet 500-mg bolus ± infusion neutralized anti-FXa activity to less than 50 ng/mL. Andexanet neutralization of thrombin generation and thromboelastometry parameters was dose and infusion time dependent.

CONCLUSION

 In a porcine polytrauma model with major bleeding on apixaban, andexanet dose dependently decreased anti-FXa activity. Lower anti-FXa levels (<50 ng/mL) with andexanet 500-mg bolus ± infusion were correlated with 60% less blood loss and 100% survival versus controls.

Antithrombotic and prohemorrhagic actions of different concentrations of apixaban in patients exposed to single and dual antiplatelet regimens

We evaluated modifications in the hemostatic balance of different concentrations of apixaban (APIX) in 25 healthy donors and 53 patients treated with aspirin (ASA, n = 21), ASA and clopidogrel (ASA + CLOPI, n = 11), or ASA and ticagrelor (ASA + TICA, n = 21). Blood samples from participants were spiked ex vivo with apixaban 0 (APIX0), 40 (APIX40), and 160 ng/mL (APIX160). We assessed the effects of APIX on (1) clot formation, by ROTEM thromboelastometry; (2) thrombin generation primed by platelets; and (3) platelet and fibrin interactions with a thrombogenic surface, in a microfluidic model with circulating blood. APIX caused dose-related prolongations of clotting time with minimal impact on other ROTEM parameters. Thrombin generation was significantly inhibited by APIX160, with ASA + TICA actions showing the strongest inhibition (p < 0.01 vs APIX0). Microfluidic studies showed that APIX160 was more potent at suppressing platelet and fibrin interactions (p < 0.001 vs. APIX0). APIX40 demonstrated a consistent antithrombotic action but with a favorable protective effect on the structural quality of fibrin. APIX potentiated the antithrombotic effects of current antiplatelet regimens. APIX at 40 ng/mL, enhanced the antithrombotic action of single or dual antiplatelet regimens but was more conservative for hemostasis than the 160 ng/mL concentration.

The European guideline on management of major bleeding and coagulopathy following trauma: sixth edition

BACKGROUND

Severe trauma represents a major global public health burden and the management of post-traumatic bleeding continues to challenge healthcare systems around the world. Post-traumatic bleeding and associated traumatic coagulopathy remain leading causes of potentially preventable multiorgan failure and death if not diagnosed and managed in an appropriate and timely manner. This sixth edition of the European guideline on the management of major bleeding and coagulopathy following traumatic injury aims to advise clinicians who care for the bleeding trauma patient during the initial diagnostic and therapeutic phases of patient management.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma included representatives from six European professional societies and convened to assess and update the previous version of this guideline using a structured, evidence-based consensus approach. Structured literature searches covered the period since the last edition of the guideline, but considered evidence cited previously. The format of this edition has been adjusted to reflect the trend towards concise guideline documents that cite only the highest-quality studies and most relevant literature rather than attempting to provide a comprehensive literature review to accompany each recommendation.

RESULTS

This guideline comprises 39 clinical practice recommendations that follow an approximate temporal path for management of the bleeding trauma patient, with recommendations grouped behind key decision points. While approximately one-third of patients who have experienced severe trauma arrive in hospital in a coagulopathic state, a systematic diagnostic and therapeutic approach has been shown to reduce the number of preventable deaths attributable to traumatic injury.

CONCLUSION

A multidisciplinary approach and adherence to evidence-based guidelines are pillars of best practice in the management of severely injured trauma patients. Further improvement in outcomes will be achieved by optimising and standardising trauma care in line with the available evidence across Europe and beyond.

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].

Coagulopathy management of multiple injured patients - a comprehensive literature review of the European guideline 2019

The European guideline on the management of trauma-induced major bleeding and coagulopathy summarises the most relevant recommendations for trauma coagulopathy management. The management of trauma-induced major bleeding should interdisciplinary follow algorithms which distinguish between life-threatening and non-life-threatening bleeding. Point-of-care viscoelastic methods (VEM) assist target-controlled haemostatic treatment. Neither conventional coagulation assays nor VEM should delay treatment in life-threatening trauma-induced bleeding. Adjustments may be rational due to local circumstances, including the availability of blood products, pharmaceuticals, and employees.

Modified thromboelastometric tests provide improved sensitivity and specificity to direct oral anticoagulants compared to standard thromboelastometric tests in-vitro

Background

The detection of direct oral anticoagulants (DOACs) is still challenging but important in emergency patients. We recently demonstrated that modified thromboelastometry can detect rivaroxaban and dabigatran. Data on the detection rates of modified compared to standard thromboelastometric tests of apixaban and edoxaban, are missing. The aim of this in-vitro dose-effect-study was to add data on these DOACs and to evaluate thromboelastometric tests in-vitro using data of both studies.

Methods

The study was approved by the Ludwig-Maximilians-University ethics committee (No 17-525-2). Written informed consent was obtained from all individuals. Blood samples of healthy volunteers and samples of 10 volunteers for each DOAC were used. Blood samples were spiked with six different concentrations of edoxaban and apixaban (0ng/ml; 31.25ng/ml; 62.5ng/ml; 125ng/ml; 250 ng/ml; 500ng/ml). Modified tests (low-tissue-factor test TFTEM and ecarin-based test ECATEM) as well as standard tests (e.g. FIBTEM) analyzing extrinsic pathway of coagulation were used. Receiver operating characteristics analyzes were performed as well as regression analyzes.

Results

TFTEM CT correlated well with anti-Xa levels of apixaban and edoxaban (apixaban: r² = 0.8064 p < 0.0001; edoxaban: r² = 0.8603; p < 0.0001). The detection of direct FXa inhibitors (> 30 ng/mL) was successful with FIBTEM CT with a sensitivity and specificity of 81% and 90%, respectively. As expected, ECATEM CT was not prolonged by direct FXa-inhibitors due to its specificity for direct thrombin inhibitors. Again, TFTEM CT provided the highest sensitivity and specificity for the detection of direct FXa inhibitors with 96% and 95%, respectively. ECATEM test showed 100% sensitivity and 100% specificity for the detection of dabigatran.

Conclusions

Our study presents modified thromboelastometric tests with improved detection of even low DOAC concentrations > 30 ng/mL, including apixaban in-vitro. The study thus complements the previously published data on dabigatran and rivaroxaban. Validation studies must confirm the results due to the explanatory design of this study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-022-00400-3.

Rapid Detection of Apixaban by a ROTEM-Based Approach and Reversibility with Andexanet Alfa or DOAC-Stop

Background  A rapid test to detect apixaban treatment would be useful in acute situations such as major bleeding, urgent surgery, or in acute thrombosis.

Objective  This article aims to study if the viscoelastic test rotational thromboelastometry (ROTEM) can rapidly detect apixaban in whole blood using modified triggers based on factor Xa (FXa) or Russell viper venom (RVV).

Method  ROTEM clotting time (CT) was measured in samples from 40 patients on apixaban treatment, and in vitro in samples spiked with apixaban (20–500 ng/mL). Commercially available trigger Ex-tem was compared with modified triggers based on FXa or RVV. Reversibility of apixaban in the samples was studied; CT was measured with and without addition of DOAC-Stop or andexanet alfa, respectively, and the difference in CT was calculated (CT _diff ).

Results  Using FXa as trigger, we detected apixaban concentrations at 20 ng/mL and above with 100% sensitivity and 100% specificity in patient samples and in vitro. Corresponding data for Ex-tem were 92% sensitivity and 100% specificity in patients, and 94% sensitivity and 100% specificity in vitro, and for RVV 97% sensitivity and 94% specificity in patients, and 97% sensitivity and 100% specificity in vitro, respectively. CT _diff data were similar. Patient sample data were obtained within 20 minutes from sampling.

Conclusion  Apixaban at low therapeutic concentrations was detected within 20 minutes, and with high sensitivity and specificity. A trigger based on FXa outperformed the commercial trigger Ex-tem and a trigger based on RVV. ROTEM with a FXa-based trigger is a promising method to detect apixaban bedside in acute settings.

Biological Variation in Rotational Thromboelastometry in Patients with Atrial Fibrillation Receiving Rivaroxaban

Rotational thromboelastometry (ROTEM) is a viscoelastic hemostasis test used primarily in the management of bleeding after trauma or in cardiac surgery. To allow safe and valid clinical interpretation of test results, objective specifications for analytical performance are needed, which are generally based on biological variation within (CVI) and between (CVG) individuals. The aim of this study was to evaluate biological variation in ROTEM in patients receiving rivaroxaban. Sixty patients with atrial fibrillation on stable rivaroxaban therapy were included, from whom blood was collected on six occasions: three times at trough and three at peak rivaroxaban concentrations. ROTEM® Extem and LowTF were measured as well as rivaroxaban concentration, PT, APTT, and anti-Xa. Within- (CVI) and between-subject (CVG) biological estimates were calculated. Knowledge of these biological variation components will help to establish the appropriate objective analytical performance specifications for ROTEM analysis.

"In Less than No Time": Feasibility of Rotational Thromboelastometry to Detect Anticoagulant Drugs Activity and to Guide Reversal Therapy

Anticoagulant drugs (i.e., unfractionated heparin, low-molecular-weight heparins, vitamin K antagonists, and direct oral anticoagulants) are widely employed in preventing and treating venous thromboembolism (VTE), in preventing arterial thromboembolism in nonvalvular atrial fibrillation (NVAF), and in treating acute coronary diseases early. In certain situations, such as bleeding, urgent invasive procedures, and surgical settings, the evaluation of anticoagulant levels and the monitoring of reversal therapy appear essential. Standard coagulation tests (i.e., activated partial thromboplastin time (aPTT) and prothrombin time (PT)) can be normal, and the turnaround time can be long. While the role of viscoelastic hemostatic assays (VHAs), such as rotational thromboelastometry (ROTEM), has successfully increased over the years in the management of bleeding and thrombotic complications, its usefulness in detecting anticoagulants and their reversal still appears unclear.

Viscoelastic Hemostatic Assays: A Primer on Legacy and New Generation Devices

Viscoelastic hemostatic assay (VHAs) are whole blood point-of-care tests that have become an essential method for assaying hemostatic competence in liver transplantation, cardiac surgery, and most recently, trauma surgery involving hemorrhagic shock. It has taken more than three-quarters of a century of research and clinical application for this technology to become mainstream in these three clinical areas. Within the last decade, the cup and pin legacy devices, such as thromboelastography (TEG^® 5000) and rotational thromboelastometry (ROTEM^® delta), have been supplanted not only by cartridge systems (TEG^® 6S and ROTEM^® sigma), but also by more portable point-of-care bedside testing iterations of these legacy devices (e.g., Sonoclot^®, Quantra^®, and ClotPro^®). Here, the legacy and new generation VHAs are compared on the basis of their unique hemostatic parameters that define contributions of coagulation factors, fibrinogen/fibrin, platelets, and clot lysis as related to the lifespan of a clot. In conclusion, we offer a brief discussion on the meteoric adoption of VHAs across the medical and surgical specialties to address COVID-19-associated coagulopathy.

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.

Rotational Thromboelastometry in High-Risk Patients on Dual Antithrombotic Therapy After Percutaneous Coronary Intervention

Aims: Patients using antithrombotic drugs after percutaneous coronary intervention (PCI) are at risk for bleeding and recurrent ischemia. We aimed to explore routine and tissue plasminogen activated (tPA) ROTEM results in a post-PCI population on dual antithrombotic treatment.

Methods and Results: In this prospective cohort, 440 patients treated with double antithrombotic therapy after recent PCI and with ≥3 risk factors for either ischemic or bleeding complications were included and compared with a control group (n = 95) consisting of perioperative patients not using antithrombotic medication. Laboratory assessment, including (tPA) ROTEM, was performed one month post-PCI and bleeding/ischemic complications were collected over a five-month follow-up. Patients were stratified by antithrombotic regimen consisting of a P2Y12 inhibitor with either aspirin (dual antiplatelet therapy; DAPT, n = 323), a vitamin K antagonist (VKA, n = 69) or a direct oral anticoagulant (DOAC, n = 48). All post-PCI patients had elevated ROTEM clot stiffness values, but only the DAPT group additionally presented with a decreased fibrinolytic potential as measured with tPA ROTEM. Patients receiving anticoagulants had prolonged clotting times (CT) when compared to the control and DAPT group; EXTEM and FIBTEM CT could best discriminate between patients (not) using anticoagulants (AUC > 0.97). Furthermore, EXTEM CT was significantly prolonged in DAPT patients with bleeding complications during follow-up (68 [62–70] vs. 62 [57–68], p = 0.030).

Conclusion: ROTEM CT has high potential for identifying anticoagulants and tPA ROTEM could detect a diminished fibrinolytic potential in patients using DAPT. Furthermore, the ability of EXTEM CT to identify patients at risk for bleeding may be promising and warrants further research.

Diagnostic Modalities in Critical Care: Point-of-Care Approach

The concept of intensive care units (ICU) has existed for almost 70 years, with outstanding development progress in the last decades. Multidisciplinary care of critically ill patients has become an integral part of every modern health care system, ensuing improved care and reduced mortality. Early recognition of severe medical and surgical illnesses, advanced prehospital care and organized immediate care in trauma centres led to a rise of ICU patients. Due to the underlying disease and its need for complex mechanical support for monitoring and treatment, it is often necessary to facilitate bed-side diagnostics. Immediate diagnostics are essential for a successful treatment of life threatening conditions, early recognition of complications and good quality of care. Management of ICU patients is incomprehensible without continuous and sophisticated monitoring, bedside ultrasonography, diverse radiologic diagnostics, blood gas analysis, coagulation and blood management, laboratory and other point-of-care (POC) diagnostic modalities. Moreover, in the time of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, particular attention is given to the POC diagnostic techniques due to additional concerns related to the risk of infection transmission, patient and healthcare workers safety and potential adverse events due to patient relocation. This review summarizes the most actual information on possible diagnostic modalities in critical care, with a special focus on the importance of point-of-care approach in the laboratory monitoring and imaging procedures.

Emergency cardiac surgery in patients on oral anticoagulants and antiplatelet medications

BACKGROUND

Emergency surgery, blood transfusion, and reoperation for bleeding have been associated with increased operative morbidity and mortality. The recent increased use of direct oral anticoagulants and antiplatelet medications has made the above more challenging. In addition, cardiopulmonary bypass (CPB), with its associated hemodilution, fibrinolysis, and platelet consumption, may exacerbate the pre-existing coagulopathy and increase the risk of bleeding.

AIM

The aim of this study was to examine available literature with regard to treating patients who are on the above medications and require emergency cardiac surgery.

RESULTS

Management decisions are typically made on a case-by-case basis. Surgery is delayed when possible, and less invasive percutaneous options should be considered if feasible. Attention is paid to exercising meticulous techniques, avoiding excessive hypothermia, and treating coexisting issues such as sepsis. Ensuring a dry operative field upon entry by correcting the coagulopathy with reversal agents is offset by the concern of potentially hindering efforts to anticoagulate the patient (heparin resistance) in preparation for CPB, in addition to possibly increasing the risk of thromboembolism.

CONCLUSION

Proper knowledge of anticoagulants, their reversal agents, and the usefulness of laboratory testing are all essential. Platelet transfusion remains the mainstay for antiplatelet medications. Four-factor prothrombin complex concentrate is considered in patients on oral anticoagulants if CPB needs to be instituted quickly. Specific reversal agents such as idarucizumab and andexanet alfa can be considered if significant tissue dissection is anticipated, such as redo sternotomy, but are costly and may lead to heparin resistance and anticoagulant rebound.

Point-of-care detection and differentiation of anticoagulant therapy - development of thromboelastometry-guided decision-making support algorithms

Background

DOAC detection is challenging in emergency situations. Here, we demonstrated recently, that modified thromboelastometric tests can reliably detect and differentiate dabigatran and rivaroxaban. However, whether all DOACs can be detected and differentiated to other coagulopathies is unclear. Therefore, we now tested the hypothesis that a decision tree-based thromboelastometry algorithm enables detection and differentiation of all direct Xa-inhibitors (DXaIs), the direct thrombin inhibitor (DTI) dabigatran, as well as vitamin K antagonists (VKA) and dilutional coagulopathy (DIL) with high accuracy.

Methods

Following ethics committee approval (No 17–525-4), and registration by the German clinical trials database we conducted a prospective observational trial including 50 anticoagulated patients (n = 10 of either DOAC/VKA) and 20 healthy volunteers. Blood was drawn independent of last intake of coagulation inhibitor. Healthy volunteers served as controls and their blood was diluted to simulate a 50% dilution in vitro. Standard (extrinsic coagulation assay, fibrinogen assay, etc.) and modified thromboelastometric tests (ecarin assay and extrinsic coagulation assay with low tissue factor) were performed. Statistical analyzes included a decision tree analyzes, with depiction of accuracy, sensitivity and specificity, as well as receiver-operating-characteristics (ROC) curve analysis including optimal cut-off values (Youden-Index).

Results

First, standard thromboelastometric tests allow a good differentiation between DOACs and VKA, DIL and controls, however they fail to differentiate DXaIs, DTIs and VKAs reliably resulting in an overall accuracy of 78%. Second, adding modified thromboelastometric tests, 9/10 DTI and 28/30 DXaI patients were detected, resulting in an overall accuracy of 94%. Complex decision trees even increased overall accuracy to 98%. ROC curve analyses confirm the decision-tree-based results showing high sensitivity and specificity for detection and differentiation of DTI, DXaIs, VKA, DIL, and controls.

Conclusions

Decision tree-based machine-learning algorithms using standard and modified thromboelastometric tests allow reliable detection of DTI and DXaIs, and differentiation to VKA, DIL and controls.

Trial registration

Clinical trial number: German clinical trials database ID: DRKS00015704.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-021-00313-7.

Hemostasis and fibrinolysis in COVID-19 survivors 6 months after intensive care unit discharge

BACKGROUND

The prothrombotic phenotype has been extensively described in patients with acute coronavirus disease 2019 (COVID-19). However, potential long-term hemostatic abnormalities are unknown.

OBJECTIVE

To evaluate the changes in routine hemostasis laboratory parameters and tissue-type plasminogen activator (tPA) rotational thromboelastometry (ROTEM) 6 months after COVID-19 intensive care unit (ICU) discharge in patients with and without venous thromboembolism (VTE) during admission.

METHODS

Patients with COVID-19 of the Maastricht Intensive Care COVID cohort with tPA ROTEM measurement at ICU and 6-month follow-up were included. TPA ROTEM is a whole blood viscoelastic assay that illustrates both clot development and fibrinolysis due to simultaneous addition of tissue factor and tPA. Analyzed ROTEM parameters include clotting time, maximum clot firmness (MCF), lysis onset time (LOT), and lysis time (LT).

RESULTS

Twenty-two patients with COVID-19 were included and showed extensive hemostatic abnormalities before ICU discharge. TPA ROTEM MCF (75 mm [interquartile range, 68-78]-59 mm [49-63]; P ≤ .001), LOT (3690 seconds [2963-4418]-1786 seconds [1465-2650]; P ≤ .001), and LT (7200 seconds [6144-7200]-3138 seconds [2591-4389]; P ≤ .001) normalized 6 months after ICU discharge. Of note, eight and four patients still had elevated fibrinogen and D-dimer concentrations at follow-up, respectively. In general, no difference in median hemostasis parameters at 6-month follow-up was observed between patients with (n=14) and without (n=8) VTE, although fibrinogen appeared to be lower in the VTE group (VTE-, 4.3 g/L [3.7-4.7] vs VTE+, 3.4 g/L [3.2-4.2]; P = .05).

CONCLUSIONS

Six months after COVID-19 ICU discharge, no persisting hypercoagulable or hypofibrinolytic profile was detected by tPA ROTEM. Nevertheless, increased D-dimer and fibrinogen concentrations persist up to 6 months in some patients, warranting further exploration of the role of hemostasis in long-term morbidity after hospital discharge.

Effect of Dabigatran on Clotting Time in the Clotpro Ecarin Clotting Assay: A Prospective, Single-Arm, Open-Label Study

Routine coagulation tests do not enable rapid, accurate determination of direct oral anticoagulant (DOAC) therapy. The ecarin clotting assay (ECA), performed on the ClotPro viscoelastic testing device, may enable sensitive and specific detection of dabigatran. We assessed the association between trough plasma dabigatran concentration and clotting time (CT) in the ClotPro ECA, in patients with non-valvular atrial fibrillation (NVAF). Each patient provided a single venous blood sample, ∼1 hour before dabigatran dosing. The study included 118 patients, of whom 64 were receiving dabigatran 110 mg twice daily and 54 were receiving 150 mg twice daily. ECA CT was moderately correlated with trough plasma dabigatran concentration (r = 0.80, p < 0.001). Slight trends toward increased plasma dabigatran concentration and prolonged ECA CT were apparent with 150 mg versus the 110 mg dose (differences not statistically significant). Individuals with creatinine clearance below 50 mL/minute had significantly higher plasma dabigatran concentrations and significantly prolonged ECA CT versus those with creatinine clearance ≥50 mL/minute. In conclusion, this preliminary study has demonstrated that CT in the ClotPro ECA reflects the plasma concentration of dabigatran in patients with NVAF. The ECA could potentially be used to assess the impact of dabigatran on a patient’s coagulation status.

ROTEM Testing for Direct Oral Anticoagulants

Direct oral anticoagulants (DOACs) are increasingly used worldwide for the prevention of stroke in patients with atrial fibrillation and to prevent or treat venous thromboembolism. In situations such as serious bleeding, the need for urgent surgery/intervention or the management of a thromboembolic event, the laboratory measurement of DOACs levels or anticoagulant activity may be required. Rotational thromboelastometry (ROTEM) is a viscoelastic hemostatic assay (VHA) which has been used in emergencies (trauma and obstetrics), and surgical procedures (cardiac surgery and liver transplants), but experience with this assay in DOACs-treated patients is still limited. This article reviews the use of ROTEM in the setting of DOACs therapy, focusing on DOACs-associated bleeding and the use of this VHA for the management of reversal strategies for DOACs-associated anticoagulation.

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.

Topical Issues in Diagnosis of Coagulopathies and Prevention of Thromboembolic Complications of Atrial Fibrillation in Patients with Liver Cirrhosis

Nowadays the comorbid pathology of liver cirrhosis and atrial fibrillation has been widely discussed and reported in the literature in the light of recent findings from the study of the effectiveness and safety of anticoagulants in this category of patients. The review is devoted to summarizing the existing data on the comorbid course of these diseases from the point of view of the impact of bleeding and thrombosis on the quality of life and mortality of patients and the possibility of using new methods of diagnosis and prevention of these complications. The purpose of the review is to focus the attention of physicians and researches on the relevance and prevalence of comorbid course of liver cirrhosis and atrial fibrillation, their complications, and discuss the benefits and possibilities of applying global methods of hemostasis assessment and anticoagulants in clinical practice. This article examines the main pathophysiological aspects of «rebalanced hemostasis» theory in liver coagulopathies, its effect on the onset of bleeding and thrombotic events, and considering the clinical benefit of the use of anticoagulants. The disadvantages of traditional coagulation assessment tests compared to the benefits of thromboelastometry (ROTEM) and thromboelastography (TEG), general fulfilling principles and evaluation of their indicators are discussed. Existing research findings on the safety and efficacy of warfarin and direct oral anticoagulants in patients with liver cirrhosis and atrial fibrillation compared with no treatment are highlighted.

Viscoelastic Haemostatic Assays in Cardiovascular Critical Care

The initiation and management of anticoagulation is a fundamental practice for a wide variety of indications in cardiovascular critical care, including the management of patients with acute MI, stroke prevention in patients with AF or mechanical valves, as well as the prevention of device thrombosis and thromboembolic events with the use of mechanical circulatory support and ventricular assist devices. The frequent use of antiplatelet and anticoagulation therapy, in addition to the presence of concomitant conditions that may lead to a propensity to bleed, such as renal and liver dysfunction, present unique challenges. The use of viscoelastic haemostatic assays provides an additional tool allowing clinicians to strike a delicate balance of attaining adequate anticoagulation while minimising the risk of bleeding complications. In this review, the authors discuss the role that viscoelastic haemostatic assay plays in cardiac populations (including cardiac surgery, heart transplantation, extracorporeal membrane oxygenation, acute coronary syndrome and left ventricular assist devices), and identify areas in need of further study.

Impact of Dabigatran Treatment on Rotation Thromboelastometry

A rapid and reliable assessment of the dabigatran effect is desirable in dabigatran treated patients with uncontrolled bleeding or before acute surgery. The aim of this study was to study the anticoagulant effects of dabigatran in patients with atrial fibrillation (AF) as assessed by the whole blood assays ROTEM, and how data from these methods correlate to plasma dabigatran concentrations measured by Hemoclot. ROTEM was performed with ROTEM Gamma (Pentapharm GmbH, Munich, Germany). The assays used in our study were Ex-tem and In-tem assay. Plasma dabigatran concentrations were determined by hemoclot thrombin inhibitor assay (Hyphen BioMed, France) at trough and post-dose in 27 patients on dabigatran 150 mg BID. Median plasma dabigatran concentrations at trough were 74 ng/mL (11.2–250) and post-dose (2 h after ingestion) 120 ng/mL (31–282). The ROTEM clotting time (CT) and maximum clot firmnes (MCF) correlated strongly with dabigatran concentrations when activated with the reagents Ex-tem (p < 0.0001) and In-tem (p < 0.0001). In summary, in our study, we have found that the ROTEM variable CT and MCF, when activated with triggers Ex-tem and In-tem, has a strong and highly significant correlation with the plasma dabigatran concentration in a real-life population of AF-patients and could thereby be an alternative to estimate dabigatran concentration in emergency situations. However, additional studies are needed to further validate these findings.

Specific Point-of-Care Testing of Coagulation in Patients Treated with Dabigatran

BACKGROUND AND PURPOSE

 Accurate and rapid assessment of coagulation status is necessary to guide thrombolysis or reversal of anticoagulation in stroke patients, but commercially available point-of-care (POC) assays are not suited for coagulation testing in patients treated with direct oral anticoagulants (DOACs). We aimed to evaluate the direct thrombin monitoring (DTM) test card by Helena Laboratories (Texas, United States) for anti-IIa-specific POC coagulation testing, hypothesizing that its POC-ecarin clotting time (POC-ECT) accurately reflects dabigatran plasma concentrations.

METHODS

 A prospective single-center diagnostic study (ClinicalTrials.gov-identifier: NCT02825394) was conducted enrolling patients receiving a first dose of dabigatran and patients already on dabigatran treatment. Blood samples were collected before drug intake and 0.5, 1, 2, 8, and 12 hours after intake. POC-ECT was performed using whole blood (WB), citrated blood (CB), and citrated plasma (CP). Dabigatran plasma concentrations were determined by mass spectrometry.

RESULTS

 In total, 240 blood samples from 40 patients contained 0 to 275 ng/mL of dabigatran. POC-ECT with WB/CB/CP ranged from 20 to 186/184/316 seconds. Pearson's correlation coefficient showed a strong correlation between dabigatran concentrations and POC-ECT with WB/CB/CP (R2  = 0.78/0.90/0.92). Dabigatran concentrations >30 and >50 ng/mL (thresholds for thrombolysis, surgery, and reversal therapy according to clinical guidelines) were detected by POC-ECT with WB/CB/CP (>36/35/45 and >43/45/59 seconds) with 95/97/97 and 96/98/97% sensitivity, and 81/87/94 and 74/60/91% specificity.

CONCLUSION

 This first study evaluating DOAC-specific POC coagulation testing revealed an excellent correlation of POC-ECT with actual dabigatran concentrations. Detecting clinically relevant dabigatran levels with high sensitivity/specificity, the DTM assay represents a suitable diagnostic tool in acute stroke, hemorrhage, and urgent surgery.

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.

A prospective observational study of the rapid detection of clinically-relevant plasma direct oral anticoagulant levels following acute traumatic injury

In urgent clinical situations, such as trauma, urgent surgery or before thrombolysis, rapid quantification of direct oral anticoagulant plasma drug levels is warranted. Using the ClotPro® analyser, we assessed two novel viscoelastic tests for detection of clinically-relevant plasma drug levels in trauma patients. The ecarin clotting time was used to assess the plasma concentration of dabigatran and Russell´s viper venom clotting time to determine the plasma concentration of direct factor Xa inhibitors. In parallel, plasma concentrations were analysed using plasma-based chromogenic assays. A total of 203 simultaneous measurements were performed. Strong to very strong linear correlations were detected between ecarin clotting time and plasma concentration of dabigatran (r = 0.9693), and between Russell´s viper venom clotting time and plasma concentrations of apixaban (r = 0.7391), edoxaban (r = 0.9251) and rivaroxaban (r = 0.8792), all p < 0.001. An ecarin clotting time ≥ 189 seconds provided 100% sensitivity and 90% specificity for detecting plasma dabigatran concentrations ≥ 50 ng.ml^-1 . Corresponding Russell´s viper venom clotting time cut-off values were ≥ 136 seconds for apixaban (80% sensitivity, 88% specificity), ≥ 168 seconds for edoxaban (100% sensitivity, 100% specificity) and ≥ 177 seconds for rivaroxaban (90% sensitivity, 100% specificity). Detection of drug levels ≥ 100 ng.ml^-1 was also investigated: for dabigatran, an ecarin clotting time ≥ 315 seconds yielded 92% sensitivity and 100% specificity; while Russell´s viper venom clotting time cut-offs of 191, 188 and 196 seconds were calculated for apixaban (67% sensitivity, 88% specificity), edoxaban (100% sensitivity, 75% specificity) and rivaroxaban (100% sensitivity, 91% specificity), respectively. We have demonstrated strong positive correlations between plasma drug levels and clotting time values in the specific ClotPro assays. Cut-off values for detecting clinically-relevant drug levels showed high levels of sensitivity and specificity.

Characterisation of antithrombin-dependent anticoagulants through clot waveform analysis to potentially distinguish them from antithrombin-independent inhibitors targeting activated coagulation factors

AIMS

While antithrombin (AT)-independent inhibitors targeting thrombin or activated factor X have been assessed through clot waveform (CWA), there are no reports on assessment with respect to AT-dependent anticoagulants. The present study aims to characterise AT-dependent anticoagulants through CWA to distinguish them from AT-independent inhibitors.

METHODS

CWA was applied to the activated partial thromboplastin time (APTT) assay of plasma samples spiked with each of AT-dependent drugs (unfractionated heparin, enoxaparin and fondaparinux) and AT-independent drugs (rivaroxaban, apixaban, edoxaban, dabigatran, argatroban, hirudin and bivalirudin), which was performed using the CS-5100 or CN-6000 (Sysmex). The APTT-CWA data were automatically gained by the analyser program. The positive mode of clotting reaction curves was defined as the direction towards fibrin generation.

RESULTS

Regarding dose-response curves in AT-dependent anticoagulants, the maximum positive values of the first and secondary derivatives (Max1 and Max_p2, respectively) and the maximum negative values of the secondary derivative (Max_n2) seemed to drop to zero without making an asymptotic line, consistent with the irreversibility. Such a feature was observed also in hirudin, as reported previously. Notably, the symmetric property of Max1 peaks in the waveforms was distorted dose dependently in AT independent but not AT-dependent drugs. A plot of Max_p2 logarithm versus Max_n2 logarithm was linear. The slope was about 1 in AT-dependent drugs while that was more than 1 in AT-independent drugs. These features made it possible to distinguish AT-dependent and AT-independent drugs.

CONCLUSIONS

The results aid in further understanding of the pharmacological aspects of anticoagulation and in screening of candidates for novel anticoagulants.

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.

Real-time detection and differentiation of direct oral anticoagulants (rivaroxaban and dabigatran) using modified thromboelastometric reagents

INTRODUCTION

Timely measurement of direct oral anticoagulants (DOACs) is challenging, though clinically important. We tested the hypotheses, that thromboelastometry is able to detect dabigatran and rivaroxaban and discriminates between dabigatran and rivaroxaban as representatives of the two groups of DOACs.

METHODS AND MATERIALS

We conducted a prospective-observational study: In-vitro dose-effect-curves for rivaroxaban and dabigatran were performed (n = 10). Ex-vivo: Patients with indication of DOAC treatment (stroke; dabigatran/rivaroxaban) were included (n = 21). Blood samples were analyzed before first intake, at first estimated peak level and at 24 h after first but before following intake and 3 h after 24 h-intake. Standard and modified thromboelastometric-assays, using low tissue factor concentrations (TFTEM) or ecarin (ECATEM) were used. Receiver-operating-characteristics-curve-analysis (ROC), regression-analysis and two-way-ANOVA were performed.

RESULTS

In-vitro: TFTEM detected dabigatran and rivaroxaban (ROC_AUC: 0.99; sensitivity/specificity: 100%/98%) but could not discriminate. Dabigatran prolongs CT_ECATEM whereas rivaroxaban did not. Clotting Time (CT)-ratio TFTEM/ECATEM discriminated highly sensitive (100%) and specific (100%) between dabigatran and rivaroxaban even at very low concentrations (ROC_AUC:1.0). CT_ECATEM correlated with dabigatran spiked concentrations (r = 0.9985; p < 0.001) and CT_TFTEM (r = 0.9363; p = 0.006) with rivaroxaban. Similarly results could be demonstrated with patient data: We confirmed the performance for the differentiation of CT-ratio TFTEM/ECATEM (sensitivity 100%/specificity 100%) at any time after first intake of either DOAC.

CONCLUSION

The thromboelastometric tests TFTEM and ECATEM detect and differentiate rivaroxaban and dabigatran. Further investigations evaluate the other DOACs and the differentiation to phenprocoumon. However, results need to be confirmed in a larger study, and especially cut off values for differentiation need to be calculated from a larger sample size.

Direct oral anticoagulant monitoring: what laboratory tests are available to guide us?

Direct oral anticoagulants (DOACs) are increasingly used in the treatment and prophylaxis of thromboembolism because of several advantages over vitamin K antagonists, including no need for laboratory monitoring. However, it has become increasingly important in certain clinical scenarios to know either actual DOAC concentration (quantitative) or presence of DOAC (qualitative). These clinical conditions include patients presenting with major bleeding or requiring urgent surgery who may need a reversal or hemostatic agent, extremes of body weight, failed therapy, etc. Prothrombin time and activated partial thromboplastin time are variably affected by factor Xa inhibitors (FXaIs) and direct thrombin inhibitor (DTI), respectively, depending on reagents' sensitivity, and hence, they cannot be relied on confidently. Thrombin time is highly sensitive to very low amounts of DTI; thus, normal value rules out a clinically significant amount. Liquid chromatography mass spectrometry accurately measures DOAC levels but is clinically impractical. Dilute thrombin time and ecarin-based assays using appropriate calibrators/controls provide an accurate DTI level. Anti-Xa assay using corresponding FXaI calibrators/controls provides accurate drug levels. However, these assays are not readily available in the United States compared with some other parts of the world. Heparin assays using anti-Xa activity often have a linear relationship with calibrated FXaI assays, especially at the lower end of on-therapy levels, and they may provide rapid assessment of drug activity for clinical decision making. Currently, there is very limited knowledge of DOAC effect on viscoelastic measurements. Although there is uniformity in expression of DOAC concentrations in nanograms per milliliter, a universal FXaI DOAC assay is urgently needed.

Timing of major fracture care in polytrauma patients - An update on principles, parameters and strategies for 2020

OBJECTIVES

Sustained changes in resuscitation and transfusion management have been observed since the turn of the millennium, along with an ongoing discussion of surgical management strategies. The aims of this study are threefold: a) to evaluate the objective changes in resuscitation and mass transfusion protocols undertaken in major level I trauma centers; b) to summarize the improvements in diagnostic options for early risk profiling in multiply injured patients and c) to assess the improvements in surgical treatment for acute major fractures in the multiply injured patient.

METHODS

I. A systematic review of the literature (comprehensive search of the MEDLINE, Embase, PubMed, and Cochrane Central Register of Controlled Trials databases) and a concomitant data base (from a single Level I center) analysis were performed. Two authors independently extracted data using a pre-designed form. A pooled analysis was performed to determine the changes in the management of polytraumatized patients after the change of the millennium. II. A data base from a level I trauma center was utilized to test any effects of treatment changes on outcome.

INCLUSION CRITERIA

adult patients, ISS > 16, admission < less than 24 h post trauma. Exclusion: Oncological diseases, genetic disorders that affect the musculoskeletal system. Parameters evaluated were mortality, ICU stay, ICU complications (Sepsis, Pneumonia, Multiple organ failure).

RESULTS

I. From the electronic databases, 5141 articles were deemed to be relevant. 169 articles met the inclusion criteria and a manual review of reference lists of key articles identified an additional 22 articles. II. Out of 3668 patients, 2694 (73.4%) were male, the mean ISS was 28.2 (SD 15.1), mean NISS was 37.2 points (SD 17.4 points) and the average length of stay was 17.0 days (SD 18.7 days) with a mean length of ICU stay of 8.2 days (SD 10.5 days), and a mean ventilation time of 5.1 days (SD 8.1 days). Both surgical management and nonsurgical strategies have changed over time. Damage control resuscitation, dynamic analyses of coagulopathy and lactate clearance proved to sharpen the view of the worsening trauma patient and facilitated the prevention of further complications. The subsequent surgical care has become safer and more balanced, avoiding overzealous initial surgeries, while performing early fixation, when patients are physiologically stable or rapidly improving. Severe chest trauma and soft tissue injuries require further evaluation.

CONCLUSIONS

Multiple changes in management (resuscitation, transfusion protocols and balanced surgical care) have taken place. Moreover, improvement in mortality rates and complications associated with several factors were also observed. These findings support the view that the management of polytrauma patients has been substantially improved over the past 3 decades.

A preliminary study using rotational thromboelastometry to investigate perioperative coagulation changes and to identify hypercoagulability in obese patients undergoing total hip or knee replacement

Surgery and obesity are known risk factors for thromboembolic events due to the presence of a hypercoagulable state. Rotational thromboelastometry is a viscoelastic assay that can provide a measure of hypercoagulability via a comprehensive assessment of the coagulation process. This prospective study investigates haemostatic changes over time, presence of hypercoagulability and the association between body mass index and thromboelastometry results in patients undergoing major orthopaedic surgery. Fifty adult patients undergoing total hip or knee replacement surgery had serial thromboelastometry measures performed prior to and following surgery, and on postoperative days 1 and 3. A hypercoagulable state, defined by an ExTEM maximum clot firmness G score ≥11 dyne/cm2, was present in 28% of the patients at baseline. The mean ExTEM maximum clot firmness G score increased by an average of three units from 10 (95% confidence interval (CI) 9–11) dyne/cm2 at baseline to 13 (95% CI 13–14) dyne/cm2 on postoperative day 3, with 85% of patients having a G score ≥11 dyne/cm2. A decrease in ExTEM and InTEM clot formation time and an increase in ExTEM, InTEM and FibTEM clot amplitude at 10 minutes, alpha angle and maximum clot firmness were observed by postoperative day 3 ( P <  0.001). There was no significant difference in the mean thromboelastometry values between patients with a body mass index <35 kg/m2or ≥35 kg/m2. Although a modest association between body mass index and the ExTEM maximum clot firmness G score was observed with exploratory data analysis, further study is required in a large cohort to test the effects of confounders, validate these findings, and determine their clinical importance.

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.

Exploring the effect of factor Xa inhibitors on rotational thromboelastometry: a case series of bleeding patients

Direct oral anticoagulants (DOACs) have become the standard for thromboembolic risk management. In cases of major bleeding, trauma, or urgent surgery, accurate monitoring of DOAC activity is desirable; however, there is often no rapid, readily available test. We therefore explored the degree to which DOAC activity correlated with two coagulation assays: rotational thromboelastometry (ROTEM) and a standard coagulation assay in bleeding patients. We conducted a retrospective review of patients who experienced bleeding while on DOAC therapy from 2015 to 2017 at a Level 1 trauma center. ROTEM (EXTEM-clotting time {CT} in seconds), activated partial thromboplastin time (aPTT) (in seconds), prothrombin time (PT) (in seconds), DOAC specific drug test (anti-Xa and Hemoclot in ng/mL), and relevant clinical parameters were recorded. Descriptive statistics (median, range) and Spearman correlation coefficients were estimated. Differences between correlations were tested using Williams' t test. Twelve cases were reviewed (13 separate bleeding episodes). Sixteen measurements of DOAC activity, EXTEM-CT, and PT were obtained. The correlations with rivaroxaban activity were 0.96 and 0.86 (p = 0.2062) for PT and EXTEM-CT, respectively. The correlations with apixaban activity were 0.63 and 0.56 (p = 0.7175) for PT and EXTEM-CT, respectively. Analyses were not conducted for dabigatran due to limited data. Although not statistically significant, PT appears to have a higher correlation with direct Xa inhibitor activity than EXTEM-CT. Further research with larger samples is necessary to clarify the differences between ROTEM and standard assays in detecting DOAC activity.

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.

Transient or extended reversal of apixaban anticoagulation by andexanet alfa is equally effective in a porcine polytrauma model

BACKGROUND

Andexanet alfa (andexanet) reverses the anticoagulant effects of factor Xa inhibitors, but it has not been assessed in clinical studies for apixaban reversal in trauma. This study evaluated andexanet for reversing apixaban anticoagulation in a porcine polytrauma model.

METHODS

Oral apixaban (20 mg q.d., n=21) or placebo (n=7; sham group) was administered to male pigs for 4 days before blunt liver injury and bi-lateral femur fracture. After trauma, animals were randomised 1:1:1 to a single andexanet bolus (1000 mg), a bolus (1000 mg) plus infusion (1200 mg over 2 h), or vehicle (control). Haemodynamic and coagulation variables were monitored for 5 h or until death. The primary endpoint was blood loss.

RESULTS

Mean blood loss in sham animals was 472 (standard deviation, 58) ml 12 min after injury and 658 (98) ml at 300 min, with 100% survival. Anticoagulation with apixaban significantly increased blood loss 12 min after injury [888 (133) ml, P<0.01]. Controls exhibited total blood loss of 3403 (766) ml, with 100% mortality. Andexanet bolus or bolus plus infusion significantly reduced blood loss to 1264 (205) and 1202 (95) ml, respectively), and increased survival to 100%. Haemodynamic parameters and markers of shock recovered to pre-trauma levels in andexanet-treated animals.

CONCLUSION

Andexanet effectively reversed apixaban anticoagulation and reduced blood loss induced by severe trauma. Andexanet bolus alone had a similar impact on survival and blood loss as bolus plus infusion. Therefore, a 2 h andexanet infusion after the bolus may not be necessary to restore normal haemostatic mechanisms.

The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition

BACKGROUND

Severe traumatic injury continues to present challenges to healthcare systems around the world, and post-traumatic bleeding remains a leading cause of potentially preventable death among injured patients. Now in its fifth edition, this document aims to provide guidance on the management of major bleeding and coagulopathy following traumatic injury and encourages adaptation of the guiding principles described here to individual institutional circumstances and resources.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004, and the current author group included representatives of six relevant European professional societies. The group applied a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were re-examined and revised based on scientific evidence that has emerged since the previous edition and observed shifts in clinical practice. New recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated.

RESULTS

Advances in our understanding of the pathophysiology of post-traumatic coagulopathy have supported improved management strategies, including evidence that early, individualised goal-directed treatment improves the outcome of severely injured patients. The overall organisation of the current guideline has been designed to reflect the clinical decision-making process along the patient pathway in an approximate temporal sequence. Recommendations are grouped behind the rationale for key decision points, which are patient- or problem-oriented rather than related to specific treatment modalities. While these recommendations provide guidance for the diagnosis and treatment of major bleeding and coagulopathy, emerging evidence supports the author group's belief that the greatest outcome improvement can be achieved through education and the establishment of and adherence to local clinical management algorithms.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. If incorporated into local practice, these clinical practice guidelines have the potential to ensure a uniform standard of care across Europe and beyond and better outcomes for the severely bleeding trauma patient.

Rotational thromboelastometry-guided perioperative management of coagulation in a patient with Heyde's syndrome undergoing transcatheter aortic valve implantation

BACKGROUND

Changes in coagulability during the hyperacute phase within 24 h after transcatheter aortic valve implantation (TAVI) for Heyde's syndrome, or aortic stenosis complicated by gastrointestinal angiodysplasia and acquired coagulation dysfunction, have not been clarified. We evaluated perioperative changes in coagulability using rotational thromboelastometry (ROTEM).

CASE PRESENTATION

A female patient with Heyde's syndrome in her 80s underwent TAVI. ROTEM showed coagulation dysfunction before and at 6 h after surgery. Improvements in coagulation function started at 12 h after surgery. Based on ROTEM findings, oral administration of antiplatelet agents was started on the day after surgery. No hemorrhagic complications were observed in the postoperative phase.

CONCLUSIONS

Evaluation of coagulation function using ROTEM was useful for monitoring perioperative hemostasis and coagulation in this patient.

Assessment of in vitro effects of direct thrombin inhibitors and activated factor X inhibitors through clot waveform analysis

Aims

Clot waveform analysis (CWA) has been reported to extend the interpretation of clotting time measurement. The parameters obtained from successive derivatives of the clotting reaction curves reflect the rates of activation of individual coagulation factors, theoretically dissecting the cascade pathway. This study aims to assess the in vitro effects of direct thrombin inhibitors (DTIs) and activated factor X (FXa) inhibitors.

Methods

CWA was applied to the activated partial thromboplastin time (APTT) assay of plasma samples spiked with each drug. For CWA of APTT measurement curves (APTT-CWA), the positive mode of clotting reaction curves was defined as the direction towards fibrin generation.

Results

All the maximum positive values in the successive derivatives were decreased dependently on the concentrations of each drug. Moreover, the negative values in the second and third derivatives appeared putatively due to consumption of thrombin and factor FXa, respectively, to form complexes with plasma serine protease inhibitors. The decrease of the maximum negative values observed dependently on the concentrations of each drug appeared to be consistent with the decreased generation of thrombin and factor FXa. The analysis of Hill coefficients of each drug in the dose–response of changes in the APTT-CWA parameters revealed a difference in anticoagulant cooperativity between DTIs versus FXa inhibitors.

Conclusions

The APTT-CWA demonstrated evidence for the blockade of thrombin-positive feedback by DTIs and FXa inhibitors and that for the differences in anticoagulant cooperativity between them. The results demonstrate the usability of CWA for assessment of anticoagulation and provide insights into direct anticoagulants.

Rapid determination of anticoagulating effects of dabigatran in whole blood with rotational thromboelastometry and a thrombin-based trigger

Essentials A rapid test to detect thrombin inhibition by dabigatran would be valuable in acute situations. A thrombin-based trigger was applied in whole blood using rotation thromboelastometry. Effects of dabigatran were assessed in vitro and in samples from patients on dabigatran. The test produced data rapidly and was sensitive to dabigatran concentrations from 20 to 500 ng mL-1 . SUMMARY: Background Rapid determination of the anticoagulant effect of dabigatran is essential in emergency situations. Objective To study a viscoelastic test (rotational thromboelastometry [ROTEM]) for rapid determination of dabigatran effects in whole blood samples. Method ROTEM measurements were performed with comparison of two triggers (thrombin-based versus the commercial tissue factor-based trigger Ex-tem) in samples from 10 healthy donors spiked with dabigatran (20-500 ng mL-1 ) and in samples from 35 patients receiving dabigatran treatment; 10 healthy subjects served as controls. Clotting time (CT) and the difference in CT without versus with addition of the dabigatran antidote idarucizumab (CTdiff ) were measured. Addition of idarucizumab reveals the contribution of dabigatran to ROTEM measurements and its potential reversibility. Results In vitro studies showed that thrombin CT and thrombin CTdiff were more sensitive than Ex-tem CT and Ex-tem CTdiff in detecting dabigatran in whole blood samples. In patient samples, when thrombin CT and thrombin CTdiff were used, it was possible to detect dabigatran with a cut-off of dabigatran at 20 ng mL-1 , whereas, when Ex-tem CT and Ex-tem CTdiff were used, the method was less sensitive. Data from patient samples were obtained within 15 min of blood sampling. Conclusions ROTEM CT with a thrombin-based trigger is more sensitive to dabigatran effects than Ex-tem CT, and detects anticoagulant effects of drug concentrations in the low-very low therapeutic range. Analysis with idarucizumab (CTdiff ) reveals dabigatran-specific effects. As data are rapidly obtained, this method could, with further development and validation of its performance, be suitable for detecting clinically significant dabigatran effects in emergency situations.

Comparison of antithrombin-dependent and direct inhibitors of factor Xa or thrombin on the kinetics and qualitative characteristics of blood clots

BACKGROUND

Venous thromboembolism (VTE) is associated with significant morbidity and mortality.

OBJECTIVES

We investigated the impact of direct and AT-dependent FXa or thrombin inhibitors on thrombus formation.

METHODS

Whole blood thromboelastometry and thrombin generation were assessed after triggering the TF pathway. Clinically relevant concentrations of rivaroxaban, fondaparinux, dabigatran or tinzaparin and an association of rivaroxaban and dabigatran were examined.

RESULTS

All agents delayed thrombus formation in a concentration-dependent manner, as documented by the prolongation of the clotting time (CT) and clot formation time (CFT). Rivaroxaban did not significantly alter the α-angle or maximum clot firmness (MCF). In contrast, dabigatran and fondaparinux altered the process of clot structure by decreasing the α-angle, but did not modify clot firmness. The later property was significantly affected only by tinzaparin that also reduced the MCF. The association of rivaroxaban and dabigatran did not affect the MCF, although it amplified the effect on CFT and α-angle.

CONCLUSIONS

All agents delayed thrombus formation. However, the compounds differed substantially with respect to fibrin polymerization rate and clot firmness. Comparison of the data obtained by thrombin generation assessment with those obtained by the thromboelastometric study shows that the delay in clot formation is principally associated with prolongation of the initiation phase of thrombin formation as well as a reduction of the propagation phase. Tinzaparin was much more potent than the other agents both with regard to suppression of thrombin generation and by delay in clot formation.