Revisiting Hartert's 1962 Calculation of the Physical Constants of Thrombelastography

Point of care guided coagulation management in adult patients on ECMO: A systematic review and meta-analysis

BACKGROUND

Despite the advancements in extracorporeal membrane oxygenation (ECMO) technology, balancing the prevention of thrombosis and the risk of bleeding in patients on ECMO is still a significant challenge for physicians. This systematic review and meta-analysis aimed to assess the efficacy and safety of viscoelastic point-of-care (POC)-guided coagulation management in adult patients on ECMO.

METHODS

PubMed Medline, Embase, Scopus, Web of Science, and Cochrane Library databases were searched. After quality assessment, meta-analysis was carried out using random effects model, heterogeneity using I2 and publication bias using Doi and Funnel plots.

RESULTS

A total of 1718 records were retrieved from the searches. Fifteen studies that enrolled a total of 583 participants met the inclusion criteria. Of those, 3 studies enrolling 181 subjects were eligible for meta-analysis. In patients managed with POC-guided algorithms, the odds were coherently lower for bleeding (OR 0.71, 95%CI 0.36-1.42), thrombosis (OR 0.91, 95%CI 0.32-2.60), and in-hospital mortality (OR 0.54, 95%CI 0.29-1.03), but not for circuit change or failure (OR 1.50, 95%CI 0.59-3.83). However, the differences were not statistically significant due to wide 95%CIs.

CONCLUSION

Viscoelastic POC monitoring demonstrates potential benefits for coagulation management in ECMO patients. Future research should focus on standardizing evidence to improve clinical decision-making.

REGISTRATION

The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) with registration ID CRD42023486294.

Blood coagulation test abnormalities in trauma patients detected by sonorheometry: a retrospective cohort study

Background

Traumatic hemorrhage guidelines include point-of-care viscoelastic tests as a standard of care. Quantra (Hemosonics) is a device based on sonic estimation of elasticity via resonance (SEER) sonorheometry to assess whole blood clot formation.

Objectives

Our study aimed to assess the ability of an early SEER evaluation to detect blood coagulation test abnormalities in trauma patients.

Methods

We conducted an observational retrospective cohort study with data collected at hospital admission of consecutive multiple trauma patients from September 2020 to February 2022 at a regional level 1 trauma center. We performed a receiving operator characteristic curve analysis to determine the ability of the SEER device to detect blood coagulation test abnormalities. Four values on the SEER device were analyzed: clot formation time, clot stiffness (CS), platelet contribution to CS, and fibrinogen contribution to CS.

Results

A total of 156 trauma patients were analyzed. The clot formation time value predicted an activated partial thromboplastin time ratio of >1.5 with an area under the curve (AUC) of 0.93 (95% CI, 0.86-0.99). The AUC of the CS value in detecting an international normalized ratio of prothrombin time of >1.5 was 0.87 (95% CI, 0.79-0.95). The AUC of fibrinogen contribution to CS to detect a fibrinogen concentration of <1.5 g/L was 0.87 (95% CI, 0.80-0.94). The AUC of platelet contribution to CS to detect a platelet concentration of <50 G/L was 0.99 (95% CI, 0.99-1.00).

Conclusion

Our results suggest that the SEER device may be useful for the detection of blood coagulation test abnormalities at trauma admission.

Retrospective study assessing outcomes in cardiac surgery after implementation of Quantra

BACKGROUND

The Quantra QPlus System is a cartridge-based device with a unique ultrasound technology that can measure the viscoelastic properties of whole blood during coagulation. These viscoelastic properties correlate directly with hemostatic function. The primary objective of this study was to assess blood product utilization in cardiac surgery patients before and after the implementation of the Quantra QPlus System.

METHODS

Yavapai Regional Medical Center implemented the Quantra QPlus System to aid in their efforts to reduce the transfusion of allogenic blood products and improve outcomes in patients undergoing cardiac surgery. A total of 64 patients were enrolled prior to the utilization of the Quantra (pre-Quantra cohort), and 64 patients were enrolled after (post-Quantra cohort). The pre-Quantra cohort had been managed via standard laboratory assays along with physician discretion for transfusion decisions. The utilization of blood products and frequency of transfusions were compared and analyzed between the two cohorts. (using the Student's t-test) RESULTS: The implementation of the Quantra resulted in a change in the pattern of blood product utilization leading to a demonstrated decrease in the amount of blood products transfused and the associated costs. The amount of FFP transfused was significantly decreased by 97% (P = 0.0004), whereas cryoprecipitate decreased by 67% (P = 0.3134), platelets decreased by 26% (P = 0.4879), and packed red blood cells decreased by 10% (P = 0.8027) however these trends did not reach statistical significance. The acquisition cost of blood products decreased by 41% for total savings of roughly $40,682.

CONCLUSIONS

Use of the Quantra QPlus System has the potential to improve patient blood management and decrease costs. STUDY REGISTERED AT CLINICALTRIALS.GOV: NCT05501730.

The Quantra System: System Description and Protocols for Measurements

Over the past two decades, the TEG 5000 (Haemonetics Corp, Braintree, MA) and ROTEM delta (Werfen, Bedford, MA) have been the principal viscoelastic (VET) technologies. These legacy technologies are based on the "cup and pin" principle. The Quantra System (HemoSonics, LLC, Durham, NC) is a new device that assesses blood viscoelastic properties by ultrasound (SEER Sonorheometry). It is cartridge based, automated device that provides simplified specimen management and increased results reproducibility. In the present chapter, we provide a description of the Quantra and its principle of operation, currently available cartridges/assays with their respective clinical indications, device operation, and results interpretation.

Measurement of Blood Viscoelasticity Using Thromboelastography

Thromboelastography (TEG) was the first viscoelastic test (VET), invented in Germany in 1948 by Dr. Hartert, and which evaluates the hemostatic competence of whole blood. Thromboelastography was introduced before the activated partial thromboplastin time (aPTT), which was devised in 1953. TEG was not widely used until the introduction of a cell-based model of hemostasis (1994) showing the importance of platelets and tissue factor in hemostasis. Nowadays, VET has become an essential method for assessing hemostatic competence in cardiac surgery, liver transplantation, and trauma. TEG has undergone several modifications, but the concept on which the original TEG was based (cup and pin technology) remained in up to the TEG 5000 analyzer (Haemonetics, Braintree, MA). A new generation of thromboelastography, TEG 6s (Haemonetics, Boston, MA), that assesses blood viscoelastic properties by resonance technology has recently been developed. This newer methodology represents a cartridge-based, automated assay aimed to improve on historical TEG performance and precision. In the present chapter, we will review the advantages and limitations of TEG 5000 and TEG 6s systems as well as factors that affect TEG and which must be considered when interpreting TEG tracings.

Operability of a Resonance-Based Viscoelastic Haemostatic Analyzer in the High-Vibration Environment of Air Medical Transport

Trauma and bleeding are associated with a high mortality, and most of these deaths occur early after injury. Viscoelastic haemostatic tests have gained increasing importance in goal-directed transfusion and bleeding management. A new generation of small-sized and thus portable ultrasound-based viscoelastic analysers have been introduced in clinical practice. We questioned whether a promising candidate can be used in emergency helicopters, with a focus on the susceptibility to vibration stress. We investigated whether the high vibration environment of an emergency helicopter would affect the operability of an ultrasound-based viscoelastic analyser and would yield reproducible results in flight and on the ground. We drew blood from 27 healthy volunteers and performed simultaneous analyses on two TEG 6s. Each measurement was performed in-flight on board an Airbus H135 emergency helicopter and was repeated on the ground, close to the flight area. Results from both measurements were compared, and the recorded tracings and numeric results were analysed for artifacts. Vibratometric measurements were performed throughout the flight in order to quantify changes in the magnitude and character of vibrations in different phases of helicopter operation. The high vibration environment was associated with the presence of artifacts in all recorded tracings. There were significant differences in citrated Kaolin + Heparinase measurements in-flight and on the ground. All other assays increased in variability but did not show significant differences between the two time points. We observed numerous artifacts in viscoelastic measurements that were performed in flight. Some parameters that were obtained from the same sample showed significant differences between in-flight and on-ground measurements. Performing resonance-based viscoelastic tests in helicopter medical service is prone to artifacts. However, a 10 min delay between initiation of measurement and take-off might produce more reliable results.

The Composition and Physical Properties of Clots in COVID-19 Pathology

Hemostasis is a finely tuned process of which dysregulation can lead either to bleeding or thrombotic complications. The latter is often caused by the hypercoagulable state as it is also seen in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, i.e., in COVID-19 patients. COVID-19 patients requiring hospitalization often suffer from thrombotic events that could not be predicted using routine coagulation assays. Recently, several studies have reported ROtational ThromboElastoMetry (ROTEM) as a promising tool to predict outcomes in COVID-19 patients. In this review we give an overview of ROTEM with a particular focus on the interpretation of the symmetrical clot formation curve in relation to coagulopathy in COVID-19 patients. Furthermore, we have introduced new parameters that might help to better distinguish between COVID-19 patients and outcomes.

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.

Hemostatic Analysis of Simulated Gloydius ussuriensis Envenomation Using Canine Blood: A Comparison of Thromboelastography and Classical Coagulation Tests

Snake envenomation may lead to venom-induced consumptive coagulopathy (VICC), usually diagnosed by classical coagulation tests (CCTs), such as prothrombin time (PT) and activated partial thromboplastin time (aPTT). However, the results of CCTs are frequently normal in the initial stages, which may delay anti-venom treatments. Thromboelastography (TEG) is a point-of-care and real-time diagnostic tool that enables a comprehensive assessment of the coagulation process. This in vitro study aimed to determine concentration-dependent changes in canine blood caused by Gloydius ussuriensis (G. ussuriensis) envenomation using TEG and CCTs. Lyophilized G. ussuriensis venom was reconstructed using mouse intravenous lethal dose 50 (LD50iv) and serially diluted to 25% LD50iv, 50% LD50iv, and 75% LD50iv to reproduce VICC at different concentrations. Normal saline was used for the control. We compared TEG values of the reaction time (R), kinetic time (K), rate of clot formation (α-angle), maximum amplitude (MA), fibrinolysis at 30 min (LY30), and global strength of the clot (G) with those of PT, aPTT, fibrinogen, and platelet counts (PLTs). Most TEG parameters, except R and LY30, demonstrated statistically significant changes compared with the control at all concentrations. CCTs, except PLTs, revealed significant changes at ≥50% LD50iv. Thus, TEG could be a useful diagnostic strategy for early VICC and preventing treatment delay.

Comparison of the resonance sonorheometry based Quantra® system with rotational thromboelastometry ROTEM® sigma in cardiac surgery - a prospective observational study

BACKGROUND

Measures of the sonorheometry based Quantra® viscoelastic hemostatic analyzer (HemoSonics, LCC, Charlottesville, VA, USA) were compared with corresponding results of the ROTEM® sigma device (Instrumentation Laboratory, Bedford, MA, USA).

METHODS

In thirty-eight patients scheduled for elective cardiac surgery between December 2018 and October 2019, blood samples were taken after induction of anesthesia (sample 1) and after heparin neutralization (sample 2) and measured on Quantra (QPlus® Cartridge) and ROTEM sigma (ROTEM® sigma complete + hep Cartridge). Clot times and clot stiffness values were recorded. Clot stiffness values of ROTEM amplitudes (A in mm) were converted to shear modulus (G) in hectoPascal (hPa): G (hPa) = (5 x A)/(100-A). Additionally, time-to-results was recorded. Spearman rank test correlation and Bland Altman analysis were performed.

RESULTS

Clot stiffness parameters of the Quantra correlated strongly with corresponding measurements of the ROTEM with r = 0.93 and 0.94 for EXTEM A10 vs CS and r = 0.94 and 0.96 for FIBTEM A10 vs FCS for sample 1 and 2, respectively. Quantra clot time correlated strongly with ROTEM INTEM CT with r = 0.71 for sample 1 and r = 0.75 for sample 2. However, Bland Altman analysis showed no agreement in all compared assays of both methods. The median time to delivery of first and complete results was significantly shorter for Quantra (412 and 658 s) compared to ROTEM sigma (839 and 1290 s).

CONCLUSIONS

The Quantra showed a strong correlation with the ROTEM sigma for determining clot times and clot stiffness and the parameters assess similar aspects of clot development. However, these parameters are not directly interchangeable and implicate that separate cut-off values need to be established for users of the Quantra device. Word count: 278.

TRIAL REGISTRATION

The study was retrospectively registered with ClinicalTrials.gov (ID: NCT04210830 ) at December 20th 2019.

Basic principles of viscoelastic testing

BACKGROUND

Viscoelastic testing is a method of hemostatic analysis that provides a real-time, holistic view of ex vivo clotting. It allows for examination of both cellular and plasma protein contributions to clotting including platelet number and function, fibrin(ogen) function, and coagulation factor function. The method assesses physical clot properties during the transition of blood from a liquid to a gel state, either by measurement of clot shear modulus using physical force transduction or by measurement of clot resonance frequency using sonometric interrogation. Results are reported in a live trace, with different trace parameters reflecting different contributors to hemostasis. These reported parameters vary between testing platforms.

RESULTS

In the United States, there are several commonly used Food and Drug Administration (FDA)-approved viscoelastic instruments available on the market. Those instruments that use sonometric clot assessment are more recently available and allow for improved portability for use near the patient's bedside. These instruments generally feature different reagent kits that allow more specific interrogation of different hemostatic pathways. Viscoelastic testing can predict the results of traditional plasma-based coagulation assays and has the added benefit of detecting hypercoagulability and severe hyperfibrinolysis. Implementation of viscoelastic testing in many clinical settings is becoming widespread and has proven to be efficacious in reducing blood transfusion rates in many settings. An impact on overall mortality and morbidity has not yet been demonstrated.

CONCLUSION

This article provides a narrative review of the basic principles of viscoelastic testing, including the science and technology behind the method, as well as currently available testing platforms and reagents.

Comparison between the new fully automated viscoelastic coagulation analysers TEG 6s and ROTEM Sigma in trauma patients: A prospective observational study

BACKGROUND

Viscoelastic coagulation testing is increasingly used to diagnose trauma-induced coagulopathy. Two fully automated analysers, TEG 6s and ROTEM Sigma, were launched recently. No previous studies have compared these devices in trauma paients.

OBJECTIVE

The aim of this study was to evaluate whether both fully automatic devices deliver comparable results.

DESIGN

Prospective observational study.

SETTING

Level one trauma centre from August 2017 to September 2018.

PATIENTS

A total of 105 blood samples from 67 trauma patients were analysed simultaneously on TEG 6s and ROTEM Sigma.

MAIN OUTCOME MEASURES

TEG 6s assays kaolin (CK), RapidTEG (CRT), kaolin with heparinase (CKH) and functional fibrinogen were compared with ROTEM Sigma assays INTEM, EXTEM, HEPTEM and FIBTEM. TEG 6s functional fibrinogen level was compared with plasma fibrinogen concentration, measured using the Clauss method. Correlations were classified as weak (Spearman correlation coefficient 0.20 to 0.39), moderate (0.40 to 0.59), strong (0.60 to 0.79) or very strong (≥0.80).

RESULTS

The TEG 6s parameters reaction time, kinetic time and α-angle (CK, CRT and CKH assays) mostly showed strong correlations with the corresponding ROTEM parameters clotting time, clot formation time and α-angle (INTEM, EXTEM and HEPTEM assays). The exceptions were CRT reaction time vs. EXTEM clotting time, and CK α-angle vs. INTEM α-angle, which correlated moderately. Absolute values for many of these parameters showed significant differences between the two devices. Very strong correlations and similar absolute values were observed between TEG 6s maximum amplitude (CRT, CK and CKH assays) and ROTEM maximum clot firmness (EXTEM, INTEM and HEPTEM assays). Correlations were also very strong for functional fibrinogen maximum amplitude vs. FIBTEM maximum clot firmness and functional fibrinogen level vs. Clauss fibrinogen concentration, but absolute values were significantly different.

CONCLUSION

Strong to very strong correlations were observed between corresponding TEG 6s and ROTEM Sigma parameters. However, absolute values showed significant differences for most of the measurements.

The effect of hematocrit, fibrinogen concentration and temperature on the kinetics of clot formation of whole blood

BACKGROUND

Dynamic mechanical analysis of blood clots can be used to detect the coagulability of blood.

OBJECTIVE

We investigated the kinetics of clot formation by changing several blood components, and we looked into the clot "signature" at its equilibrium state by using viscoelastic and dielectric protocols.

METHODS

Oscillating shear rheometry, ROTEM, and a dielectro-rheological device was used.

RESULTS

In fibrinogen- spiked samples we found the classical high clotting ability: shortened onset, faster rate of clotting, and higher plateau stiffness. Electron microscopy explained the gain of stiffness. Incorporated RBCs weakened the clots. Reduction of temperature during the clotting process supported the development of high moduli by providing more time for fiber assembly. But at low HCT, clot firmness could be increased by elevating the temperature from 32 to 37°C. In contrast, when the fibrinogen concentration was modified, acceleration of clotting via temperature always reduced clot stiffness, whatever the initial fibrinogen concentration. Electrical resistance increased continuously during clotting; loss tangent (D) (relaxation frequency 249 kHz) decreased when clots became denser: fewer dipoles contributed to the relaxation process. The relaxation peak (Dmax) shifted to lower frequencies at higher platelet count.

CONCLUSION

Increasing temperature accelerates clot formation but weakens clots. Rheometry and ROTEM correlate well.

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.

Viscoelastic Monitoring to Guide the Correction of Perioperative Coagulopathy and Massive Transfusion in Patients with Life-Threatening Hemorrhage

The resuscitation of patients with traumatic hemorrhage remains a challenging clinical scenario. The appropriate and aggressive support of the patient's coagulation is of critical importance. Conventional coagulation assays present several shortcomings in this setting. The integration of viscoelastic monitoring in clinical practice has the potential to result in significant improvements. In order to be successful, the provider must understand basics of the methodology, read outs, and the limitations of the technique.

Viscoelastic Monitoring to Guide Hemostatic Resuscitation in Liver Transplantation Surgery

Coagulopathic bleeding must be anticipated during liver transplantation (LT) surgery. Patients with end-stage liver disease (ESLD) often present with disease-related hematologic disturbances, including the loss of hepatic procoagulant and anticoagulant clotting factors and thrombocytopenia. Transplantation surgery itself presents additional hemostatic changes, including hyperfibrinolysis. Viscoelastic monitoring (VEM) is often used to provide targeted, personalized hemostatic therapies for complex bleeding states including cardiac surgery and major trauma. The use in these coagulopathic conditions led to its application to LT, although the mechanisms of coagulopathy in these patients are quite different. While VEM is often used during transplant surgeries in Europe and North America, evidence supporting its use is limited to a few small clinical studies. The theoretical and clinical applications of the standard and specialized VEM assays are discussed in the setting of LT and ESLD.

Endothelial Cell-derived Extracellular Vesicles Size-dependently Exert Procoagulant Activity Detected by Thromboelastometry

Endothelial cells (ECs) are major modulators of hemostasis by expressing and releasing pro- and anticoagulant mediators into the circulation. Previous studies showed that cultured ECs release procoagulant mediators into cell culture supernatants as evidenced by the reduction of viscoelastic clotting time. This effect was reversed with an anti-tissue factor antibody. Here, we aimed to investigate whether tissue factor (TF) was released by endothelial-derived extracellular vesicles (EVs) and which portion of the released vesicles displays the most prominent procoagulant properties. After stimulation of ECs with tumor-necrosis factor-α (TNF-α) the supernatants of EC cultures were subjected to differential centrifugation steps to collect larger and smaller EVs which were then characterised by nanoparticle tracking analysis (NTA) and flow cytometry. Mixed with fresh human blood and analysed by thromboelastometry EVs exerted a significant procoagulant stimulus, which could be partly reversed by addition of an anti-TF antibody. Moreover, TF activity was confirmed in the centrifuged fractions. In summary, our results provide evidence of the procoagulant potential of smaller and larger endothelial-derived EV fractions detected by thromboelastometry. The observed effect is most likely due to the release of TF-bearing EVs of different dimensions, which are released upon TNF-α stimulation of endothelial cell cultures.

Comparison of citrated and fresh whole blood for viscoelastic coagulation testing during elective neurosurgery

BACKGROUND

Previous viscoelastic haemostatic tests studies have often indicated a hypercoagulative test signal with citrated blood, which could influence clinical decision makings.

PURPOSE

The aim of this study was to compare fresh and citrated whole blood using two non-automated viscoelastic ROTEM and Sonoclot tests. Our hypothesis was that citrated blood would demonstrate a hypercoagulative response in this setting, not tested before.

METHODS

Perioperative viscoelastic coagulation changes were evaluated with a ROTEM and Sonoclot in 38 patients undergoing elective brain tumor surgery. The citrated samples were recalcified with CaCl₂. Wilcoxon nonparametric-paired tests and Bland-Altman plots were performed to compare the fresh and citrated blood analyses.

RESULTS

The citrated blood showed a hypercoagulative response in ROTEM NATEM-clot formation time and α-angle, Sonoclot-clot rate and platelet function, as compared to fresh blood (p<0.0001).

CONCLUSIONS

Fresh whole blood may theoretically reflect in vivo haemostasis more closely than citrated analyses, which indicated a hypercoagulative response as compared to the fresh whole blood analyses Bland-Altman plots also indicated that ROTEM reference ranges in patients undergoing brain surgery should be redefined. Future studies must establish the correlation between viscoelastic test results using fresh or citrate anticoagulated blood and clinical outcomes, such as bleeding, transfusion or reoperation for postoperative haematoma.

[Rotational thromboelastometry for the diagnosis of coagulation disorders]

BACKGROUND

Compared to conventional coagulation assays, as prothrombin time (PT) or activated partial thromboplastin time (aPTT), viscoelastic methods of coagulation analysis, including rotational thromboelastometry (ROTEM®, Tem International GmbH, Munich, Germany), yield prognostic benefits. Results of ROTEM® in citrated whole blood could be generated within 10-12 min and allow for a qualitative and semiquantitative characterisation of clot kinetics. Based on ROTEM® results, the switch between empiric approaches of treating coagulopathy to a goal-directed approach could be accelerated. Introduction of ROTEM® reduces transfusion requirements and the need for single factor concentrates. Thus, ROTEM® reduces transfusion-related adverse events, and additionally implement therapeutic cost effectiveness.

OBJECTIVES

This review provides a short introduction in the methodology of ROTEM®, showing how the combination of assays with different commercially available ROTEM® reagents allows for rapid differential diagnosis of common coagulopathies in clinical practice. Furthermore, prognostic benefits and limitations of ROTEM® diagnostics are described. Finally, we discuss the potential fields of ROTEM® application in different surgical settings.

CONCLUSION

ROTEM® appears to be a contemporary, applicable and effective method in diagnosing coagulopathy and for subsequent algorithm-based goal-directed therapy.

Is viscoelastic coagulation monitoring with ROTEM or TEG validated?

Recent years have seen increasing worldwide interest in the use of viscoelastic coagulation monitoring tests, performed using devices such as ROTEM and TEG. The use of such tests to guide haemostatic therapy may help reduce transfusion of allogeneic blood products in bleeding patients and is supported in European guidelines for managing trauma and severe perioperative bleeding. In addition, viscoelastic tests form the basis of numerous published treatment algorithms. However, some publications have stated that viscoelastic tests are not validated. A specific definition of the term validation is lacking and regulatory requirements of the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) have been fulfilled by ROTEM and TEG assays. Viscoelastic tests have been used in pivotal clinical trials, and they are approved for use in most of the world's countries. Provided that locally approved indications are adhered to, the regulatory framework for clinicians to use viscoelastic tests in routine clinical practice is in place.