Measurement of Blood Viscoelasticity Using Thromboelastography

Innovative Diagnostic Solutions in Hemostasis

Hemostasis describes the process of blood clotting homeostasis. Hemostasis reflects a balance of procoagulant and anticoagulant mechanisms that aim to prevent both bleeding and thrombosis. If hemostasis is disrupted, and bleeding or thrombosis occur, then laboratory testing may ensue to either diagnose the reason for bleeding or thrombosis, or to manage patients under therapy or treatment for bleeding or thrombosis. A wide range of tests of hemostasis are available to laboratories and to clinicians, from routine coagulation assays to specialized hemostasis assays and platelet function. In the current narrative review, we highlight some of the history of innovative diagnostic solutions, such as the integration of chemiluminescence and flow cytometry in the hemostasis diagnostic armamentarium, as well as providing a glimpse to the possible future of diagnostic hemostasis testing. Future directions include the potential for artificial intelligence in diagnostics, the development of more global test systems that can assess both primary and secondary hemostasis, and several innovations to enable the ongoing evolution of therapies to rebalance hemostasis and requiring precise monitoring. This review underscores the ongoing need for innovation to enhance the diagnostic landscape of hemostasis, ensuring better patient outcomes through more accurate and efficient diagnostic methods.

International Council for Standardization in Haematology Guidance for New Lot Verification of Coagulation Reagents, Calibrators, and Controls

The clinical laboratory uses commercial products with limited shelf life or certain expiry dates requiring frequent lot changes. Prior to implementation for clinical use, laboratories should determine the performance of the new reagent lot to ensure that there is no significant shift in reagent performance or reporting of patient data. This guideline has been written on behalf of the International Council for Standardization in Haematology (ICSH) to provide the framework and provisional guidance for clinical laboratories for evaluating and verifying the performance of new lot reagents used for coagulation testing. These ICSH Working Party consensus recommendations are based on good laboratory practice, regulatory recommendations, evidence emerged from scientific publications, and expert opinion and are meant to supplement regional standards, regulations, or requirements.

The Role of Viscoelastic Testing in Assessing Hemostasis: A Challenge to Standard Laboratory Assays?

Viscoelastic testing is increasingly being used in clinical and research settings to assess hemostasis. Indeed, there are potential situations in which viscoelastic testing is reportedly superior to standard routine laboratory testing for hemostasis. We report the current testing platforms and terminology, as well as providing a concise narrative review of the published evidence to guide its use in various clinical settings. Notably, there is increasing evidence of the potential utility of viscoelastic testing for assessment of direct oral anticoagulants, and bleeding associated with chronic liver disease, orthotopic liver transplantation, cardiac surgery, trauma, obstetrics and pediatrics.

Hemostasis Testing in the Emergency Department: A Narrative Review

Routine laboratory screening is typically performed at initial evaluation of the vast majority of presentations to the emergency department (ED). These laboratory results are crucial to the diagnostic process, as they may influence up to 70% of clinical decisions. However, despite the usefulness of biological assessments, many tests performed are inappropriate or of doubtful clinical relevance. This overutilization rate of laboratory testing in hospitals, which represents a significant medical-economic burden, ranges from 20 to 67%, with coagulation tests at the top of the list. While reviews frequently focus on nonintensive care units, there are few published assessments of emergency-specific interventions or guidelines/guidance to date. The aim of this review is to highlight current recommendations for hemostasis evaluation in the emergency setting with a specific analysis of common situations leading to ED admissions, such as suspected venous thrombosis or severe bleeding. We revisit the evidence related to the assessment of patient's hemostatic capacity based on comprehensive history taking and physical examination as well as best practice recommendations for blood sample collection to ensure the reliability of results. This review also includes an examination of various currently available point of care tests and a comprehensive discussion on indications, limitations, and interpretation of these tests.

Simplified Method for Removing Direct Oral Anticoagulant Interference in Mechanical Coagulation Test Systems-A Proof of Concept

BACKGROUND

Direct oral anticoagulants (DOACs) cause unwanted interference in various hemostasis assays, including lupus anticoagulant (LA) testing, where false positive and false negative identification may occur. DOAC Stop (DS) is an activated charcoal (AC) product used to specifically and effectively adsorb DOACs from test plasma. This process normally requires plasma treatment, centrifugation and plasma separation prior to tests, but inexperienced operators may also inadvertently transfer residual AC particles, thereby potentially adversely affecting clot detection.

METHODS

We hypothesized that residual DS might not be problematic for mechanical clot detection. We therefore investigated the potential impact of DS and a new DS liquid (DS-L) product on clotting tests using a mechanical clot detection system. Varying concentrations of DS were added to normal and abnormal plasmas with and without DOAC presence. Clotting tests including PT, APTT and dRVVT were performed directly in the analyzer without plasma/DS centrifugation.

RESULTS

DS up to double the recommended treatment level had only minor effects on all test results, despite completely obscuring visibility in the plasma/reagent mix. This confirms that the centrifugation step may be able to be omitted when using mechanical detection systems.

CONCLUSIONS

Should DS carryover into treated plasmas occur, this should not cause issues with testing performed on mechanical clot-sensing devices. Moreover, we hypothesize that DS can be used directly in these systems, without the need for centrifugation, thereby simplifying its many potential applications.

Comparison of Two Viscoelastic Testing Devices in a Parturient Population

Background: Viscoelastic hemostatic assays (VHAs) have become an integral diagnostic tool in guiding hemostatic therapy, offering new opportunities in personalized hemostatic resuscitation. This study aims to assess the interchangeability of ClotPro® and ROTEM® delta in the unique context of parturient women. Methods: Blood samples from 217 parturient women were collected at three timepoints. A total of 631 data sets were eligible for our final analysis. The clotting times were analyzed via extrinsic and intrinsic assays, and the clot firmness parameters A5, A10, and MCF were analyzed via extrinsic, intrinsic, and fibrin polymerization assays. In parallel, the standard laboratory coagulation statuses were obtained. Device comparison was assessed using regression and Bland-Altman plots. The best cutoff calculations were used to determine the VHA values corresponding to the established standard laboratory cutoffs. Results: The clotting times in the extrinsic and intrinsic assays showed notable differences between the devices, while the extrinsic and intrinsic clot firmness results demonstrated interchangeability. The fibrinogen assays revealed higher values in ClotPro® compared to ROTEM®. An ROC analysis identified VHA parameters with high predictive values for coagulopathy exclusion and yet low specificity. Conclusions: In the obstetric setting, the ROTEM® and ClotPro® parameters demonstrate a significant variability. Device- and indication-specific transfusion algorithms are essential for the accurate interpretation of measurements and adequate hemostatic therapy.