Viscoelastic Tests Research Articles

Perioperative hemostatic management of patients with type A aortic dissection.

Coagulopathy is common in patients undergoing thoracic aortic repair for Stanford type A aortic dissection. Non-critical administration of blood products may adversely affect the outcome. It is therefore important to be familiar with the pathologic conditions that lead to coagulopathy in complex cardiac surgery. Adequate care of these patients includes the collection of the medical history regarding the use of antithrombotic and anticoagulant drugs, and a sophisticated diagnosis of the coagulopathy with viscoelastic testing and subsequently adapted coagulation therapy with labile and stable blood products. In addition to the above-mentioned measures, intraoperative blood conservation measures as well as good interdisciplinary coordination and communication contribute to a successful hemostatic management strategy.

Scenario Decision-Making About Plasma and Platelet Transfusion for Intracranial Monitor Placement: Cross-Sectional Survey of Pediatric Intensivists and Neurosurgeons.

To report pediatric intensivists' and pediatric neurosurgeons' responses to case-based scenarios about plasma and platelet transfusions before intracranial pressure (ICP) monitor placement in children with severe traumatic brain injury (TBI). Cross-sectional, electronic survey to evaluate reported plasma and platelet transfusion decisions in eight scenarios of TBI in which ICP monitor placement was indicated. Survey administered through the Pediatric Acute Lung Injury and Sepsis Investigators and the American Association of Neurologic Surgeons. Pediatric intensivists and pediatric neurosurgeons. None. A total of 184 participants responded (85 identified as pediatric intensivists and 54 as pediatric neurosurgeons). In all eight scenarios, the majority of respondents reported that they would base their decision-making about plasma transfusion on international normalized ratio (INR) alone (60-69%), or platelet transfusion on platelet count alone (83-86%). Pediatric intensivists, as opposed to pediatric neurosurgeons, more frequently reported that they would have used viscoelastic testing in their consideration of plasma transfusion (32% vs. 7%, p < 0.001), as well as to guide platelet transfusions (29 vs. 8%, p < 0.001), for the case-based scenarios. For all relevant case-based scenarios, pediatric neurosurgeons in comparison with pediatric reported that they would use a lower median (interquartile range [IQR]) INR threshold for plasma transfusion (1.5 [IQR 1.4-1.7] vs. 2.0 [IQR 1.5-2.0], p < 0.001). Overall, in all respondents, the reported median platelet count threshold for platelet transfusion in the case-based scenario was 100 (IQR 50-100) ×10 9 /L, with no difference between specialties. Despite little evidence showing efficacy, when we tested specialists' decision-making, we found that they reported using INR and platelet count in pediatric case-based scenarios of TBI undergoing ICP monitor placement. We also found that pediatric intensivists and pediatric neurosurgeons had differences in decision-making about the scenarios.

Evaluation of hemostatic derangements associated with canine anaphylaxis and the relationship to syndrome severity.

To describe hemostatic derangements associated with canine anaphylaxis and to assess for association with syndrome severity. Prospective observational study. University teaching hospital. Twenty-seven client-owned dogs, recruited from November 2018 to January 2022, diagnosed with anaphylaxis of varying severity were included. Study inclusion required presentation <6hours after initiation of clinical signs, no medications or history of illness within the prior 2weeks, lack of comorbidities expected to affect hemostasis, and lack of a disease state that could alternatively explain the clinical presentation. Blood samples were collected within the first hour of presentation for CBC, serum biochemistry, prothrombin time (PT), activated partial thromboplastin time (aPTT), and viscoelastic coagulation testing for use with a cartridge-based point-of-care device. Clotting time and clot formation time were prolonged, alpha angle and maximum clot firmness were decreased, PT and aPTT were prolonged, and platelet counts were lower in severe cases compared to mild and moderate cases. There were no differences for any parameter between mild and moderate cases. The presence or absence of abdominal effusion was not associated with hemostatic status. Global hemostatic derangements consistent with hypocoagulability are a prominent feature of severe anaphylaxis in dogs and should be considered for routine evaluation.

Concentration–effect relationship for tranexamic acid inhibition of tissue plasminogen activator-induced fibrinolysis in vitro using the viscoelastic ClotPro® TPA-test

BackgroundTranexamic acid is an antifibrinolytic drug that is commonly administered for obstetric haemorrhage. Conventional viscoelastic tests are not sensitive to tranexamic acid, but the novel ClotPro® TPA-test can measure tranexamic acid-induced inhibition of fibrinolysis. We aimed to evaluate the TPA-test in pregnant and non-pregnant women. MethodsWe performed an in vitro study of whole blood samples spiked with tranexamic acid from pregnant women in the first, second, and third trimester (n=20 per group) and from non-pregnant women (n=20). We performed ClotPro TPA-tests of whole blood sample and ClotPro EX-tests, FIB-tests, and TPA-tests. ResultsClot lysis was inhibited in a concentration-dependent manner up to a tranexamic acid concentration of 6.25 mg L−1. At tranexamic acid concentrations of 12.5 mg L−1 and above, clot lysis was completely inhibited. The concentration–effect relationship of tranexamic acid did not differ in a clinically important manner in blood from pregnant women across all three trimesters or from non-pregnant controls. A median maximum lysis cut-off value of at9 least 16% (25–75th percentiles 15–18), a median clot lysis time of 3600 s (25–75th percentiles 3600–3600), or both was associated with a tranexamic acid concentration of least 12.5 mg L−1. ConclusionsThe ClotPro® TPA-test is sensitive in detecting inhibition of fibrinolysis by tranexamic acid in whole blood samples of pregnant and non-pregnant women. The concentration–effect relationship of tranexamic acid to inhibit fibrinolysis in whole blood did not differ for women in the first, second, and third trimester or for non-pregnant women.

Point-of-care, goal-directed management of bleeding in trauma patients.

The purpose of this review is to consider the clinical value of point-of-care (POC) testing in coagulopathic trauma patients with traumatic brain injury (TBI) and trauma-induced coagulopathy (TIC). Patients suffering from severe TBI or TIC are at risk of developing pronounced haemostatic disorders. Standard coagulation tests (SCTs) are insufficient to reflect the complexity of these coagulopathies. Recent evidence has shown that viscoelastic tests (VETs) identify haemostatic disorders more rapidly and in more detail than SCTs. Moreover, VET results can guide coagulation therapy, allowing individualised treatment, which decreases transfusion requirements. However, the impact of VET on mortality remains uncertain. In contrast to VETs, the clinical impact of POC platelet function testing is still unproven. POC SCTs are not able to characterise the complexity of trauma-associated coagulopathy. VETs provide a rapid estimation of underlying haemostatic disorders, thereby providing guidance for haemostatic therapy, which impacts allogenic blood transfusion requirements. The value of POC platelet function testing to identify platelet dysfunction and guide platelet transfusion is still uncertain.

Monitoring of Argatroban in Critically Ill Patients: A Prospective Study Comparing Activated Partial Thromboplastin Time, Point-of-Care Viscoelastic Testing with Ecarin Clotting Time and Diluted Thrombin Time to Mass Spectrometry.

The direct thrombin inhibitor argatroban is indicated for the treatment of heparin-induced thrombocytopenia II, but it is also used off-label to treat critically ill patients presenting with heparin resistance, severe antithrombin deficiency, or hypercoagulability. Direct drug monitoring is not routinely available, and argatroban dosing is mainly based on global coagulation assays such as activated partial thromboplastin time (PTT) or diluted thrombin time (TT), both of which have limitations in patients with hypercoagulability. Blood samples were obtained from critically ill patients treated with argatroban. Activated PTT and diluted TT were measured with a STA R Max3 analyzer (STAGO Deutschland GmbH, Germany) using an argatroban-calibrated kit. Ecarin clotting time was measured using a point-of-care viscoelastic test device. Liquid chromatography with tandem mass spectrometry was performed using a reversed-phase column, a solvent gradient, and an API4000 mass spectrometer with electrospray. Correlation was described using Pearson correlation coefficient r and Bayesian multilevel regression to estimate relationships between outcomes and covariates. From June 2021 to March 2022, 205 blood samples from 22 patients were analyzed, allowing for 195 activated PTT-liquid chromatography with tandem mass spectrometry comparisons, 153 ecarin clotting time-liquid chromatography with tandem mass spectrometry comparison, and 105 diluted TT-liquid chromatography with tandem mass spectrometry comparisons. Compared to liquid chromatography with tandem mass spectrometry, performance of argatroban quantification was best for diluted TT (r = 0.91), followed by ecarin clotting time (r = 0.58) and activated PTT (r = 0.48). Regression analysis revealed that patients with sepsis were more prone to argatroban overdosing (coefficient, 4.194; 95% credible interval, 2.220 to 6.792). Although activated PTT monitoring of argatroban is the most commonly used test, in critically ill patients, diluted TT provides more precise measurements. Alternately, point-of-care viscoelastic ecarin clotting time also provides guidance for argatroban dosing to identify overdosing if available. The data also suggested that patients with sepsis are at greater risk for argatroban overdosing.

Precision medicine in hemostasis: a review of prothrombin complex concentrates and the role of viscoelastic tests in tailoring therapy

This review explores the role of precision medicine in the management of bleeding disorders and anticoagulation therapy, with a focus on the use of visco-elastic tests such as Thromboelastography (TEG) and Rotational Thromboelastometry (ROTEM). These tests provide real-time, dynamic insight into a patient's coagulation status, guiding the choice between three-factor prothrombin complex concentrate (PCC3) and four-factor PCC (PCC4), as well as the use of activated four-factor PCC (FEIBA). The specific ROTEM tests, INTEM and EXTEM, further enhance our understanding of the intrinsic and extrinsic coagulation pathways. Moreover, the use of tranexamic acid (TXA) and fibrinogen, guided by these visco-elastic tests, has shown promise in trauma patients. TXA has been associated with survival benefit when administered immediately or within 3 hours of injury. Fibrinogen, a key factor in clot formation, can be monitored and supplemented as needed to optimize hemostasis. In conclusion, the practice of precision medicine, with the aid of TEG and ROTEM, offers the potential to enhance the safety and efficacy of PCC therapy, TXA administration, and fibrinogen supplementation. These tools are invaluable in tailoring therapy to the specific needs of each patient, potentially optimizing patient outcomes and minimizing the risk of adverse events.

Unraveling the critical indicators for evaluating the high-temperature performance of rejuvenator-aged bitumen blends

This study aims to systematically investigate the influence of rejuvenator type/dosage and the aging degree of bitumen on the rutting resistance, flow behavior, and elastic/creep potential of rejuvenated bitumen at high temperatures. The rutting parameter (G*/sinδ), rutting failure temperature (RFT) from Linear viscoelastic test (LVE), zero-shear viscosity (ZSV) from flow test, recovery percentage (R0.1, R3.2), creep compliance (Jnr0.1, Jnr3.2), and stress sensitivity parameters (Rdiff, Jnrslope) from multiple stress creep and recovery (MSCR) tests of rejuvenated bitumen are characterized. The results reveal that bio-oil rejuvenator weakens the high-temperature performance of aged bitumen maximally, followed by engine-oil and naphthenic-oil, while aromatic-oil rejuvenated bitumen exhibits the best rutting, flow, and creep resistance. The RFT index can most effectively evaluate and differentiate the rejuvenation efficiency of various rejuvenators on the high-temperature performance, which correlates well with ZSV, R3.2, Jnr0.1, Jnr3.2, Rdiff, and Jnrslope indices. Therefore, the RFT index is recommended as the critical indicator for evaluating the high-temperature performance of rejuvenated binders. The flow and MSCR characteristics of rejuvenated bitumen can be predicted based on RFT values. The determination of critical indicators is beneficial to compare the rejuvenation effectiveness of variable rejuvenators on the high-temperature performance of aged bitumen.

OA4‐AM23‐ST‐10 | Viscoelastic Testing is Paradoxically Confounded by Hematocrit in Clinical Samples Tested on Both Rotational Torsion and Harmonic Resonance Platforms

OA4‐AM23‐ST‐10 | Viscoelastic Testing is Paradoxically Confounded by Hematocrit in Clinical Samples Tested on Both Rotational Torsion and Harmonic Resonance Platforms

PB1221 Prospective Study Comparing Point-of-Care Viscoelastic Testing and Standard Laboratory Testing for the Prediction of Bleeding Complications in Patients after Systemic Thrombolysis Therapy

PB1221 Prospective Study Comparing Point-of-Care Viscoelastic Testing and Standard Laboratory Testing for the Prediction of Bleeding Complications in Patients after Systemic Thrombolysis Therapy

PB1035 Monitoring of Unfractionated Heparin in Critical ill ICU Patients: A Prospective Study Comparing aPTT and Point-of-Care Viscoelastic Testing with IN/HI Ratio to Anti-Xa

PB1035 Monitoring of Unfractionated Heparin in Critical ill ICU Patients: A Prospective Study Comparing aPTT and Point-of-Care Viscoelastic Testing with IN/HI Ratio to Anti-Xa

PB1034 Monitoring of Argatroban in Critical Ill Patients: A Prospective Study Comparing aPTT, Point-of-Care Viscoelastic Testing with Ecarin Clotting Time and dTT to LC/MS/MS

PB1034 Monitoring of Argatroban in Critical Ill Patients: A Prospective Study Comparing aPTT, Point-of-Care Viscoelastic Testing with Ecarin Clotting Time and dTT to LC/MS/MS

ERAS Cardiac Society turnkey order set for patient blood management: Proceedings from the AATS ERAS Conclave 2023

ObjectivesThere are multiple published guidelines on comprehensive patient blood management (PBM), centered on the 3 pillars of PBM: managing preoperative anemia, minimizing blood loss, and tolerating intraoperative/postoperative anemia. We sought to create an order set to facilitate widespread implementation of evidence-based PBM for cardiac surgery patients. MethodsSubject matter experts were consulted to translate existing guidelines and literature into a sample turnkey order set (TKO) for PBM. Orders derived from consistent class I, class IIA, or equivalent recommendations across referenced guidelines and consensus manuscripts appear in the TKO in bold type. Selected orders that were inconsistently class I or IIA, class IIB, or supported by published evidence are presented in italic type. ResultsPreoperatively, there are strong recommendations to screen and treat preoperative anemia with iron replacement and erythropoietin and to discontinue dual antiplatelet therapy if the patient can safely wait for surgery. Intraoperative orders outline the routine use of an antifibrinolytic agent, cell saver, point of care viscoelastic testing, and use of a standard transfusion algorithm. The order set also reflects strong recommendations intraoperatively and postoperatively for agreed-upon hemoglobin thresholds to consider transfusion of packed red blood cells. A hemoglobin threshold should be adopted according to local team consensus and should trigger a discussion regarding transfusion. ConclusionsThe benefit of a multidisciplinary PBM care pathway in cardiac surgery has been well established, yet implementation remains variable. Using recommendations from existing guidelines, we have created a TKO to facilitate the implementation of PBM.

PB0087 Use of Viscoelastic Tests in the Intensive Care Unit for the Evaluation of Haemostasis in SARS-COV-2 Infection

PB0087 Use of Viscoelastic Tests in the Intensive Care Unit for the Evaluation of Haemostasis in SARS-COV-2 Infection

Characteristics of blood clotting on thromboelastography in patients with early burns

BackgroundThromboelastography (TEG) is a viscoelastic test that may be used to evaluate the hemostatic function of whole blood, and it may be useful for burn patients with multiple hemostatic defects. MethodsWe retrospectively recruited patients with burns between January 2019 and July 2021. Blood samples were drawn on admission and subjected to coagulation parameter assessment, including conventional coagulation tests and TEG assessment. Receiver operating characteristic (ROC) analysis was performed to predict the occurrence of complications in patients with early burns. ResultsNinety-three patients with early burns met the inclusion criteria. Patients with minor, moderate, severe, and extremely severe burns accounted for 19.4 %, 36.6 %, 16.1 %, and 27.9 % of all patients, respectively. Compared with the healthy controls, patients with early burns showed significant reductions in the R and K values, and significant elevation in the maximum amplitude (MA), coagulation index (CI), and alpha angle. Compared with minor and moderate burn patients, patients with severe and extremely severe burns had lower K values and thrombin time and higher alpha angle, CI, prothrombin time, international normalized ratio, D-dimer, and fibrin degradation products. Patients with hypercoagulation had lower R and K values, longer MA, longer CI, and greater alpha angle. After ROC analysis, the areas under the ROC curve for acute lung injury, acute kidney injury, and bleeding were 0.789, 0.802, and 0.900, respectively. ConclusionTEG provides insight into the hemostatic state of patients with early burns, and can predict complications in early burn patients when combined with conventional coagulation tests.

Hemostatic Profiles of Patients Who Underwent Transcatheter Versus Surgical Aortic Valve Replacement Versus Percutaneous Coronary Intervention

Guidelines for transcatheter aortic valve replacement (TAVR) antithrombotic prophylaxis are extrapolated predominantly from percutaneous coronary intervention (PCI) data. Here, we examined temporal coagulation changes occurring in the early perioperative period to determine the pathobiologic validity of this supposition. This was a prospective observational study of consecutive patients who underwent transfemoral TAVR (n=27), PCI (n=12), or surgical aortic valve replacement (SAVR) requiring cardiopulmonary bypass and cross-clamping (n=12). Blood samples were taken at 4 time points: T1 (baseline), after general anesthesia or sedation; T2, after heparin administration; T3, at the end of the procedure; and T4, 6 hours after the procedure. The samples were assessed concurrently using standard laboratory coagulation tests and viscoelastic tests of whole blood clotting, including the latest generation thromboelastometry (ROTEM sigma) and thromboelastometry (TEG 6s). Patients in the TAVR cohort were older and a had lower baseline hemoglobin level than patients in the PCI and SAVR cohorts. The baseline platelet function was similar between the TAVR and PCI cohorts and impaired in the SAVR cohort Figure S1. The baseline hemostatic measures were comparable among cohorts. Regarding the per-patient change from baseline, the TAVR cohort showed an overall more prothrombotic state than the other cohorts, with the most marked differences from the SAVR cohort after intraoperative heparin administration and from the PCI cohorts 6hours after the procedure. In addition, the ROTEM and TEG parameters were well correlated but not interchangeable. In conclusion, patients who underwent TAVR have a more prothrombotic hemostatic profile than PCI and SAVR patients. These findings question the current guidelines that extrapolate antithrombotic regimens from PCI to TAVR settings.

Does heparin rebound lead to postoperative blood loss in patients undergoing cardiac surgery with cardiopulmonary bypass?

Heparin rebound is a common observed phenomenon after cardiac surgery with CPB and is associated with increased postoperative blood loss. However, the administration of extra protamine may lead to increased blood loss as well. Therefore, we want to investigate the relation between heparin rebound and postoperative blood loss and the necessity to provide extra protamine to reverse heparin rebound. We searched PubMed, Cochrane, EMBASE, Google Scholar and Web of Science to review the question: "Does heparin rebound lead to postoperative blood loss in patients undergoing cardiac surgery with cardiopulmonary bypass." Combination of search words were framed within four major categories: heparin rebound, blood loss, cardiac surgery and cardiopulmonary bypass. All studies that met our question were included. Quality assessment was performed using the Cochrane risk of bias (RoB2) tool for randomized controlled trials and the risk of bias in non-randomized studies of intervention (ROBINS-I) for non-randomised trials. 4 randomized and 17 non-randomized studies were included. The mean incidence of heparin rebound was 40%. The postoperative heparin levels, due to heparin rebound, were often below or equal to 0.2 IU/mL. We could not demonstrate an association between heparin rebound and postoperative blood loss or transfusion requirements. However the quality of evidence was poor due to a broad variety of definitions of heparin rebound, measured by various coagulation tests and studies with small sample sizes. The influence of heparin rebound on postoperative bleeding seems to be negligible, but might get significant in conjunction with incomplete heparin reversal or other coagulopathies. For that reason, it might be useful to get a picture of the entire coagulation spectrum after cardiac surgery, as can be done by the use of a viscoelastic test in conjunction with an aggregometry test.

Platelet Reactivity on ECMO: Role of VerifyNow

Viscoelastic assays help in identifying disorders of clotting factors, platelet function, and detection of excessive fibrinolysis. Rotational thromboelastometry (ROTEM) assesses quantitative and qualitative aspects of whole blood coagulation which allows for the determination of the mechanism of hemostatic disturbance. This helps clinicians in targeting the correct blood component therapy transfusion. Now, using verify we aim to study platelet reactivity, VA ECMO which will reflect the platelet aggregation response to an aggregating agent like Aspirin and thus know the etiology of bleeding on VA ECMO, to know the right component therapy to be transfused with a Point of Care test. For extracorporeal membrane oxygenation, although the conventional laboratory tests are used to monitor anticoagulation on whole blood, viscoelastic tests reflect coagulation status like no other standard laboratory tests. They show the status of color propagation, formation, and stabilization. It was reported that platelet function was impaired over time in all parameters with different activators.

Viscoelastic Testing on Venoarterial Extracorporeal Membrane Oxygenation: Need or Greed?

Extracorporeal life support (ECLS) is a life support modality that is being used in life-threatening cardiac and/or respiratory failure; in neonates, children, and adults. The risk of bleeding and other coagulation-related issues is unavoidable. Hence, while conducting ECLS, a patient-tailored approach is better than the generalized approach for bleeding management. There are no established guidelines for heparin use and its monitoring during ECLS in a bleeding patient on VA ECMO. Likewise, heparin and its adjuncts, though mentioned in the literature, have no consensus on what exact steps to follow in an adverse condition. Having a protocol for anticoagulation and its monitoring is of paramount importance in any center practicing ECLS. This review aims to seek the incidence of bleeding and thrombosis while on ECMO with the use of routine anticoagulant heparin and justify the need for the use of viscoelastic tests on VA ECMO.

Fibrinolytic potential as a risk factor for postpartum hemorrhage.

Postpartum hemorrhage (PPH) is still the leading cause of maternal morbidity and mortality worldwide. While impaired fibrin polymerization plays a crucial role in the development and progress of PPH, recent approaches using viscoelastic measurements have failed to sensitively detect early changes in fibrinolysis in PPH. This study aimed to evaluate whether women experiencing PPH show alterations in POC-VET fibrinolytic potential during childbirth and whether fibrinolytic potential offers benefits in the prediction and treatment of PPH. Blood samples were collected at three different timepoints: T0 = hospital admission (19 h ± 18 h prepartum), T1 = 30-60 min after placental separation, and T2 = first day postpartum (19 h ± 6 h postpartum). In addition to standard laboratory tests, whole-blood impedance aggregometry (Multiplate) and viscoelastic testing (VET) were performed using the ClotPro system, which included the TPA-test lysis time, to assess the POC-VET fibrinolytic potential, and selected coagulation factors were measured. The results were correlated with blood loss and clinical outcome markers. Severe PPH was defined as a hemoglobin drop > 4g/dl and/or the occurrence of shock or the need for red blood cell transfusion. Blood samples of 217 parturient women were analyzed between June 2020 and December 2020 at Heidelberg University Women's Hospital, and 206 measurements were eligible for the final analysis. Women experiencing severe PPH showed increased fibrinolytic potential already at the time of hospital admission. When compared to non-PPH, the difference persisted 30-60 min after placental separation. A higher fibrinolytic potential was accompanied by a greater drop in fibrinogen and higher d-dimer values after placental separation. While 70% of women experiencing severe PPH showed fibrinolytic potential, 54% of those without PPH showed increased fibrinolytic potential as well. We were able to show that antepartal and peripartal fibrinolytic potential was elevated in women experiencing severe PPH. However, several women showed high fibrinolytic potential but lacked clinical signs of PPH. The findings indicate that high fibrinolytic potential is a risk factor for the development of coagulopathy, but further conditions are required to cause PPH.