TEG® and ROTEM® Traces: Clinical Applications of Viscoelastic Coagulation Monitoring in Neonatal Intensive Care Unit

The frequency and timing of sepsis-associated coagulopathy in the neonatal intensive care unit

Introduction

Sepsis is a common cause of morbidity and mortality in the neonatal intensive care unit (NICU). The frequency and severity of sepsis-associated coagulopathy as well as its relationship to illness severity are unclear.

Methods

We performed a single-center, retrospective, observational cohort study of all infants admitted to the University of Florida Health (UF Health), level IV NICU between January 1st 2012 to March 1st 2020 to measure the frequency of sepsis-associated coagulopathy as well as its temporal relationship to critical illness in the NICU population. All clinical data in the electronic health record were extracted and deposited into an integrated data repository that was used for this work.

Results

We identified 225 new sepsis episodes in 216 patients. An evaluation for sepsis-associated coagulopathy was performed in 96 (43%) episodes. Gram-negative pathogen, nSOFA score at evaluation, and mortality were greater among episodes that included a coagulopathy evaluation compared with those that did not. Abnormal coagulation results were common (271/339 evaluations; 80%) and were predominantly prothrombin times. Intervention (plasma or cryoprecipitate) followed a minority (84/271; 31%) of abnormal results, occurred in 40/96 (42%) episodes that were often associated with >1 intervention (29/40; 73%), and coincided with thrombocytopenia in 37/40 (93%) and platelet transfusion in 27/40 (68%). Shapley Additive Explanations modeling demonstrated strong predictive performance for the composite outcome of death and/or treatment for coagulopathy in neonates (f1 score 0.8, area under receiver operating characteristic curve 0.83 for those with abnormal coagulation values). The three most important features influencing the composite outcome of death or treatment for coagulopathy included administration of vasoactive medications, hematologic dysfunction assessed by the maximum nSOFA platelet score, and early sepsis (≤72 h after birth).

Conclusions

A coagulopathy evaluation was performed in a minority of NICU patients with sepsis and was associated with greater illness severity and mortality. Abnormal results were common but infrequently associated with intervention, and intervention was contemporaneous with thrombocytopenia. The most important feature that influenced the composite outcome of death or treatment for coagulopathy was the administration of vasoactive-inotropic medications. These data help to identify NICU patients at risk of sepsis-associated coagulopathy.

Quick model-based viscoelastic clot strength predictions from blood protein concentrations for cybermedical coagulation control

Cybermedical systems that regulate patient clotting in real time with personalized blood product delivery will improve treatment outcomes. These systems will harness popular viscoelastic assays of clot strength such as thromboelastography (TEG), which help evaluate coagulation status in numerous conditions: major surgery (e.g., heart, vascular, hip fracture, and trauma); liver cirrhosis and transplants; COVID-19; ICU stays; sepsis; obstetrics; diabetes; and coagulopathies like hemophilia. But these measurements are time-consuming, and thus impractical for urgent care and automated coagulation control. Because protein concentrations in a blood sample can be measured in about five minutes, we develop personalized, phenomenological, quick, control-oriented models that predict TEG curve outputs from input blood protein concentrations, to facilitate treatment decisions based on TEG curves. Here, we accurately predict, experimentally validate, and mechanistically justify curves and parameters for common TEG assays (Functional Fibrinogen, Citrated Native, Platelet Mapping, and Rapid TEG), and verify results with trauma patient clotting data.

Neutralization, by a polyspecific antivenom, of the coagulopathy induced by the venom of Bothrops asper: Assessment by standard coagulation tests and rotational thromboelastometry in a murine model

Venom-induced consumption coagulopathy and thrombocytopenia are common and potentially severe manifestations of viperid snakebite envenoming since they contribute to local and systemic hemorrhage. Therefore, the assessment of the efficacy of antivenoms to neutralize coagulopathic and thrombocytopenic toxins should be part of the preclinical evaluation of these drugs. To evaluate the efficacy of the polyvalent (Crotalinae) antivenom produced in Costa Rica, in this study we have used a mouse model of coagulopathy and thrombocytopenia induced by the venom of Bothrops asper, based on the bolus intravenous (i.v.) injection of venom. When venom and antivenom were incubated before injection, or when antivenom was administered i.v. immediately after venom injection, venom-induced hemostatic alterations were largely abrogated. We also studied the recovery rate of clotting parameters in conditions where antivenom was administered when mice were coagulopathic. Some parameters recovered more rapidly in antivenom-treated mice than in control envenomed animals, but others showed a spontaneous recovery without antivenom. This is due to a rapid clearance of plasma venom levels in these experimental conditions. This implies that models based on the bolus i.v. injection of venom have limitations for assessing the effect of antivenom in the recovery of clotting alterations once coagulopathy has developed. It is suggested that alternative models should be developed based on a slower systemic absorption of venom. Overall, our findings provide a protocol for the preclinical evaluation of antivenoms and demonstrate that the polyvalent antivenom is effective in neutralizing the toxins of B. asper venom responsible for coagulopathy and thrombocytopenia.

Comparison of a viscoelastic point-of-care coagulation monitor with thromboelastography in sick dogs with hemostatic abnormalities

BACKGROUND

Viscoelastic coagulation monitor (VCM-Vet) is a point-of-care device that has been used to characterize hemostatic abnormalities in sick pets but has not been validated in veterinary patients.

OBJECTIVES

We aimed to compare VCM-Vet and thromboelastography (TEG) in sick dogs with suspected disorders of hemostasis.

METHODS

Duplicate VCM-Vet tests using untreated native blood performed concurrently on two VCM-Vet machines, and simultaneous TEG tests were performed (one citrated native (CN), and one activated with tissue factor (TF) at a 1:3600 dilution). Each VCM-Vet result was compared with both TF-activated and CN TEG.

RESULTS

Fifty-three dogs were enrolled. Eleven cases displayed apparent hyperfibrinolysis. Spearman correlation coefficients for individual VCM-Vet devices and CN and TF TEG were obtained between R and CT values and ranged from 0.21 to 0.27, CFT and K (r = 0.60-0.67), angles (r = 0.51-0.62), and MCF and MA (r = 0.85-0.87). Comparison of the two VCM-Vet devices displayed positive correlations for all clot formation parameters with Lin's concordance correlation coefficients of 0.75-0.95. Variable lysis parameter agreement existed between the VCM-Vet devices and VCM-Vet and TEG. When samples were classified as hypercoagulable or coagulopathic, VCM-Vet had a low positive predictive value (17-33%) for the detection of hypercoagulable states and a moderate negative predictive value (64-74%) for the detection of coagulopathy as defined by TEG.

CONCLUSIONS

VCM-Vet and TEG had variable correlations in clot formation values and a strong correlation for final clot strength. More information is needed to make conclusions about the lysis parameters. Artifact in the fibrinolysis portion of the test can confound the interpretation of VCM-Vet results.

ROTEM and Bivalirudin: The Confounding Challenges Ahead

Direct thrombin inhibitors directly bind to active sites on thrombin and exert their anticoagulant effect. Bivalirudin is used an alternative in cases of heparin-induced thrombocytopenia, heparin resistance, anaphylactic reaction to UFH, or anti-thrombin III deficiency. Here, we report a case of a 31-year-old female patient, diagnosed with recurrent chronic thromboembolic pulmonary hypertension posted for redo pulmonary thromboendarterectomy. Monitoring anticoagulation during bivalirudin therapy is sometimes confounding and challenging. Prolongation of CT on INTEM and HEPTEM has shown moderate to strong correlation with traditional laboratory tests like aPTT and HPTT (aPTT with Hepzyme). ROTEM can be a way forward for monitoring bivalirudin therapy.

Reference Values of Thromboelastometry Parameters in Healthy Term Neonates Using NATEM in Cord Blood Samples

Background: ROTEM assay has gained increasing acceptance as a method for rapid and specific coagulation pathway assessment. However, its use in the neonatal population remains limited since reference ranges have not yet been established. Aims: (1) to determine reference ranges for healthy term neonates of ROTEM parameters using non-activated assay (NATEM) in cord blood samples; (2) to assess whether delivery mode, gender, gestational age, birth weight and blood group (ABO and Rhesus) of the neonate, coagulation disorder and anticoagulant medication of the mother have an impact on NATEM parameters. Methods: NATEM assay was conducted in cord blood samples of 189 term neonates without any medical history. Results: Reference ranges (2.5th and 97.5th percentiles) are established for clotting time (CT), clot formation time (CFT), α-angle, clot amplitude at 5, 10 and 20 min (A5, A10, A20), maximum clot firmness (MCF), lysis index at 30 and 60 min (LI30, LI60, %) and maximum clot elasticity (MCE). Reference ranges for NATEM are CT 182-499 s, CFT 63-176 s, α-angle 58-78°, A5 28-52 mm, A10 37-61 mm, A20 42-66 mm, MCF 43-67 mm, LI30 97-100%, LI60 87-98% and MCE 75-203. Male neonates appear to be more hypocoagulable than females. Conclusions: We demonstrate reference ranges for healthy term neonates in NATEM assay that could be used as a reference group for future studies of neonates with an underlying pathology.