Clinical utility of the Quantra ® point‐of‐care haemostasis analyser during urgent cardiac surgery

Viscoelastic testing: Critical appraisal of new methodologies and current literature

United States Food and Drug Administration (FDA)-approved viscoelastic testing (VET) methodologies have significantly changed in the last 10 years, with the availability of cartridge-based VET. Some of these cartridge-based methodologies use harmonic resonance-based clot detection. While VET has always allowed for the evaluation of real-time clot formation, cartridge-based VET provides increased ease of use as well as greater portability and robustness of results in out-of-laboratory environments. Here we review the use of VET in a variety of clinical contexts, including cardiac surgery, trauma, liver transplant, obstetrics, and hypercoagulable states such as COVID-19. As of now, high quality randomized trial evidence for new generation VET (TEG 6s, HemoSonics Quantra, ROTEM sigma) is limited. Nevertheless, the use of VET-guided transfusion algorithms appears to result in reduced blood usage without worsening of patient outcomes. Future work comparing the new generation VET instruments and continuing to validate clinically important cut-offs will help move the field of point-of-care coagulation monitoring forward and increase the quality of transfusion management in bleeding patients.

Assessment of a Quantra-Guided Hemostatic Algorithm in High-Bleeding-Risk Cardiac Surgery

OBJECTIVES

To assess whether a Quantra-guided hemostatic algorithm would reduce transfusion requirement and major bleeding compared with laboratory-guided testing in patients facing high-bleeding-risk cardiac surgery.

DESIGN

Single-center before-and-after study.

SETTING

University hospital.

PARTICIPANTS

Patients facing high-bleeding-risk cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

Hemostatic algorithm was based on standard laboratory testing during the control period, then on the Quantra during the Quantra period. The primary endpoint was the number of red blood cell (RBC) units transfused on day 1 after surgery.

MEASUREMENTS AND MAIN RESULTS

After propensity-score matching, 66 patients were included in the Quantra group and 117 in the control group. The Quantra group received fewer RBC units on day 1 than the control group (2 [0-5] v 4 [2-6], p = 0.016, respectively). Intraoperatively, the Quantra group received fewer RBC (2 [0-3] v 3 [1-5], p = 0.005), less fresh frozen plasma (0 [0-3] v 3[2-5], p < 0.0001), and fewer platelet units (7.5 [0-10] v 8.2 [6.3-11.7], p = 0.014). The intraoperative rates of RBC, plasma, and platelet transfusion were reduced (64% v 78%, p = 0.05; 41% v 85%, p < 0.001; 55% v 82%, p = 0.001, respectively). The RBC and plasma transfusions were reduced on days 1, 2, and 7. The incidence of major bleeding on day 1 also was reduced (36% v 56%, p = 0.014). In multivariate analysis, implementation of the Quantra-guided hemostatic algorithm was associated independently with reductions in major bleeding.

CONCLUSION

Implementation of a Quantra-based hemostatic algorithm was associated with a decrease in transfusion requirement and major bleeding after high-bleeding-risk cardiac surgery. Randomized trials are needed to confirm these results.

Are Viscoelastometric Assays of Old Generation Ready for Disposal? Comment on Volod et al. Viscoelastic Hemostatic Assays: A Primer on Legacy and New Generation Devices. J. Clin. Med. 2022, 11, 860

With the advent of new viscoelastometric hemostatic assay (VHA) devices, with ready-to-use cartridge reagents allowing for their use by people without special laboratory skills, the appreciation of the actual clinical value of VHAs in settings such as severe trauma, post-partum hemorrhage, cardiac surgery and liver transplantation still needs to be fully validated. While two of the newest versions remain based on a 'cup and pin' system (ROTEM^® sigma, ClotPro^®), two other new devices (TEG^® 6s, Quantra^®) rely on very different technologies: clotting blood is no longer in contact with the probe and challenged by oscillation of one of the components but explored with ultrasound exposure. A systematic literature search (including Sonoclot^®) retrieved 20 observational studies (19 prospective). Most studies pointed to imperfect agreements, highlighting the non-interchangeability of devices. Only a few studies, often with a limited number of patients enrolled, used a clinical outcome. No study compared VHA results with conventional laboratory assays obtained through a rapid tests panel. Clinical evidence of the utility of the new VHAs largely remains to be proven through randomized clinical trials, with clinically relevant outcomes, and compared to rapid panel hemostasis testing. The availability of new, improved VHA devices provides an impetus and an opportunity to do so.

Efficacy of sonorheometry point of the care device in determining low fibrinogen levels in pregnant blood: an invitro dilution and reconstitution study

Quantra® Hemostasis Analyzer is a Point of the care device that uses ultrasound technology to assess clot formation. In this study, we establish how Quantra® system performs compared to conventional coagulation tests at low levels of fibrinogen in the blood obtained from pregnant women. 24 mL blood was obtained from each healthy parturient. Blood was analyzed for Quantra® variables (Q): Clot time (CT), Clot stiffness (CS), platelet contribution to CS (PCS), fibrinogen contribution to CS (FCS), and conventional coagulation (CL) tests: PT, aPTT, INR, Factor VIII and fibrinogen. 6 ml blood were centrifuged to obtain pregnant plasma. 30 mL of saline was added to 10 mL of blood to simulate crystalloid resuscitation (DB) and was evaluated for Q and CL. Fractions of pregnant plasma, or nonpregnant plasma (Blood Bank) was added to DB to obtain 15% and 30% clotting factor enriched samples. 4 ml of DB was added to 4 ml of original blood (1:1) to obtain the final sample (resus). Each of the samples were analyzed for Q and CL parameters. Regression analysis and Receiving Characteristics Curves were used to study the relationship between Quantra variables and CL tests. There were remarkably high linear correlations between Fibrinogen and CS (R = 0.93, P < 0.001), fibrinogen and FCS (R = 0.77, P < 0.001). An FCS value 2.45 (sensitivity of 79.2 and specificity of 97.3%), and CS value 10.85 hPa (sensitivity of 83% and specificity of 100%) predicted fibrinogen of 200 mg/dL. This study demonstrates a good correlation between Quantra® CS, FCS and serum fibrinogen.Clinical Trial Number: NCT04301193.

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.

Viscoelastic hemostatic assays: Update on technology and clinical applications

Viscoelastic hemostatic assays (VHA) are point of care tests that allow for a global assessment of coagulation using whole blood. The technology to allow this assessment has evolved from the original thromboelastography (TEG, Haemonetic, Boston, MA) to now include thromboelastometry (ROTEM, Instrumentation Laboratory, Bedford, MA), and, most recently, the Quantra Hemostasis Analyzer (Hemosonics, Charlottesville, VA). Diagnosis and treatment algorithms incorporating viscoelastic hemostatic tests for bleeding patients in a variety of clinical situations have now been developed. The original ROTEM and TEG technologies have been updated with emphasis placed on a cartridge-based technologies. Results from the new devices show good correlation with those from the previous versions of the devices, while cartridge-based technology has increased device stability and enhanced portability to the bedside. In this article, we will review recent advances in TEG and ROTEM technology and introduce the Quantra Hemostasis Analyzer device.

The Year in Coagulation: Selected Highlights from 2020

This is the second annual review in the Journal of Cardiothoracic and Vascular Anesthesia to cover highlights in coagulation for cardiac surgery. The goal of this article is to provide readers with a focused summary from the literature of the prior year's most important coagulation topics. In 2020, this included a discussion covering allogeneic transfusion, antiplatelet and anticoagulant therapy, factor concentrates, coagulation testing, mechanical circulatory support, and the effects of coronavirus disease 2019.

Managing the coagulopathy associated with cardiopulmonary bypass

Cardiopulmonary bypass (CPB) has allowed for significant surgical advancements, but accompanying risks can be significant and must be expertly managed. One of the foremost risks is coagulopathic bleeding. Increasing levels of bleeding in cardiac surgical patients at the time of separation from CPB are associated with poor outcomes and mortality. CPB-associated coagulopathy is typically multifactorial and rarely due to inadequate reversal of systemic heparin alone. The components of the bypass circuit induce systemic inflammation and multiple disturbances of the coagulation and fibrinolytic systems. Anticipating coagulopathy is the first step in managing it, and specific patient and procedural risk factors have been identified as predictors of excessive bleeding. Medication management pre-procedure is critical, as patients undergoing cardiac surgery are commonly on anticoagulants or antiplatelet agents. Important adjuncts to avoid transfusion include antifibrinolytics, and perfusion practices such as red cell salvage, sequestration, and retrograde autologous priming of the bypass circuit have varying degrees of evidence supporting their use. Understanding the patient's coagulation status helps target product replacement and avoid larger volume transfusion. There is increasing recognition of the role of point-of-care viscoelastic and functional platelet testing. Common pitfalls in the management of post-CPB coagulopathy include overdosing protamine for heparin reversal, imperfect laboratory measures of thrombin generation that result in normal or near-normal laboratory results in the presence of continued bleeding, and delayed recognition of surgical bleeding. While challenging, the effective management of CPB-associated coagulopathy can significantly improve patient outcomes.