FIBTEM clot firmness parameters correlate well with the fibrinogen concentration measured by the Clauss assay in patients and healthy subjects

Fibrinogen levels in severe trauma: A preliminary comparison of Clauss Fibrinogen, ROTEM Sigma, ROTEM Delta and TEG 6s assays from the FEISTY pilot randomised clinical trial

OBJECTIVE

To describe the relationships between different methods of measuring functional fibrinogen levels in severely injured, bleeding trauma patients across multiple timepoints during hospitalisation.

METHODS

In 100 adult trauma patients enrolled in the FEISTY pilot randomised clinical trial at four tertiary trauma centres in Australia, blood samples were collected prospectively. Consistency of agreement was calculated, comparing functional fibrinogen levels measured by four methods - ROTEM® Delta and Sigma FIBTEM A5, TEG® 6s CFF MA, and gold-standard Clauss Fibrinogen.

RESULTS

Comparing the ROTEM® Delta and new-generation ROTEM® Sigma machine, consistency of agreement for FIBTEM A5, measured by calculating intraclass correlation coefficients (ICCs), was ≥0.73 across all analysed timepoints, with mean differences (Sigma minus Delta) of 0.10-3.57 mm. Corresponding values comparing the ROTEM® Sigma FIBTEM A5 and TEG® 6s CFF MA were ICC = 0.55-0.82 and ICC = 4.69-7.97 (CFF MA minus A5). Comparing ROTEM® Sigma FIBTEM A5 and Clauss Fibrinogen Analysis (CFA), among statistically significant simple linear regression models, R2 was 0.25-0.67, and comparing TEG® 6s CFF MA and CFA (CFA) 0.65-0.82, although not all differences were significant with the latter comparison. Relationships across all timepoints combined were Clauss Fibrinogen (CF) (g/L) = 0.21𝑥 + 0.004 (where 𝑥 = ROTEM® Sigma FIBTEM A5 in mm) and (g/L) = 0.16𝑥 - 0.06 (where 𝑥 = TEG® 6s CFF MA in mm).

CONCLUSIONS

The present study revealed acceptable agreement between four different assays measuring functional fibrinogen, with current- and previous-generation ROTEM® machines (Sigma, Delta) performing similarly measuring functional fibrinogen via FIBTEM assay. This suggests that haemostatic resuscitation algorithms designed for the ROTEM® Delta can be applied to the ROTEM® Sigma to guide fibrinogen replacement.

Assessment of hemostasis in hyperthyroid and euthyroid cats using two viscoelastic assays and platelet aggregometry

BACKGROUND

Hyperthyroidism in humans is associated with a hypercoagulable state and an increased risk of thromboembolism.

OBJECTIVE

To evaluate hemostatic variables in hyperthyroid and euthyroid cats with the hypothesis that hyperthyroid cats will have evidence of altered hemostasis consistent with a potential hypercoagulable state.

ANIMALS

Client-owned hyperthyroid (n = 16) and euthyroid (n = 15) cats over 8 years of age.

METHODS

Prospective observational study. Hyperthyroid and euthyroid cats were enrolled. Rotational thromboelastometry (ROTEM), whole-blood platelet impedance aggregometry (WBPIA) and a point-of-care viscoelastic coagulation monitor (VCM-Vet) were performed immediately after minimally traumatic venipuncture under sedation.

RESULTS

Hyperthyroid cats had significantly higher values for variables as assessed by VCM-Vet: A10 (34 [17-47] vs 25 [17-38], P = .003); A20 (39.5 [23-55] vs 31 [21-45], P = .003); and MCF (41 [24-58] vs 35 [22-49], P = .03). Hyperthyroid cats had significantly different values versus the euthyroid cohort as assessed by different ROTEM channels: increased A10, INTEM (61.5 [39-75] vs 54 [23-66], P = .007) and FIBTEM (18 [10-35] vs 13 [2-27], P = .01); increased A20, INTEM (68 [45-78] vs 61 [30-70], P = .006) and FIBTEM (17 [10-34] vs 11 [2-25], P = .002); increased MCF, EXTEM (72 [65-81] vs 69 [34-78], P = .04), INTEM (70 [45-85] vs 62 [35-71], P = .01) and FIBTEM (18 [13-37] vs 14 [3-27], P = .02); increased alpha angle, EXTEM (80 [68-85] vs 76 [41-84], P = .01); shortened CT, EXTEM (52.5 [29-73] vs 60 [52-92], P = .003) and FIBTEM (52.5 [16-75] vs 65 [53-165], P = .001); and decreased ML, FIBTEM (20 [1-36] vs 33 [19-59], P <.001). No significant differences were found with WBPIA.

CONCLUSIONS AND CLINICAL IMPORTANCE

The hyperthyroid cats in this study had evidence of altered hemostasis as assessed by 2 viscoelastic methodologies, and characterized by increased clot amplitude, firmness, and faster coagulation times vs euthyroid controls.

Diagnostic value of clot formation parameters determined by rotational thromboelastometry in 63 patients with congenital dysfibrinogenemia

Rotational thromboelastometry (ROTEM) is a global hemostasis assay. The diagnosis added value of ROTEM in congenital dysfibrinogenemia remains to be established. The aim of this study was to analyze clot formation by ROTEM in a cohort of dysfibrinogenemic patients and to establish correlations with genotype, clinical features, and coagulation parameters. The study included genetically confirmed congenital dysfibrinogenemia cases (n = 63) and healthy controls ( n  = 50). EXTEM, INTEM, FIBTEM tests were used to measure ROTEM parameters, that is, clotting time (CT), clot formation time (CFT), maximal clot firmness (MCF) and amplitude 10 min after CT (A10). The ISTH bleeding assessment tool was used to determine bleeding episodes. CT (INTEM) was statistically significantly shorter in congenital dysfibrinogenemia patients compared to controls while CFT (EXTEM) was prolonged. Patients's MCF in EXTEM, INTEM, and FIBTEM were similar to controls while A10 (FIBTEM) was statistically significantly lower. Fibrinogen activity was positively correlated with fibrinogen antigen, A10 and MCF in all three assays. Bleeding phenotypes were observed in 23 (36.5%) patients. Only CFT in EXTEM and CT in INTEM were statistically different in patients with bleeding phenotype versus controls. Carriers of the FGA mutation p.Arg35His had a CT (EXTEM) slightly prolonged and a reduced A10 (FIBTEM) compared to controls. Some ROTEM parameters were able to distinguish congenital dysfibrinogenemia patients from controls, and patients with a bleeding phenotype. Prolonged CFT in EXTEM were associated with congenital dysfibrinogenemia and bleeding phenotype. Bleeding episodes in most patients were generally mild and prevalence of thrombosis was very low.

The nature and timing of coagulation dysfunction in a cohort of trauma patients in the Australian pre-hospital setting

BACKGROUND

Acute Traumatic Coagulopathy (ATC) is a complex pathological process that is associated with patient mortality and increased blood transfusion requirements. It is evident on hospital arrival, but there is a paucity of information about the nature of ATC and the characteristics of patients that develop ATC in the pre-hospital setting. The objective of this study was to describe the nature and timing of coagulation dysfunction in a cohort of injured patients and to report on patient and pre-hospital factors associated with the development of ATC in the field.

METHODS

This was a prospective observational study of a convenience sample of trauma patients. Patients had blood taken during the pre-hospital phase of care and evaluated for derangements in Conventional Coagulation Assays (CCA) and Rotational Thromboelastometry (ROTEM). Associations between coagulation derangement and pre-hospital factors and patient outcomes were evaluated.

RESULTS

A total of 216 patients who had either a complete CCA or ROTEM were included in the analysis. One hundred and eighty (83 %) of patients were male, with a median injury severity score of 17 [interquartile range (IQR) 10-27] and median age of 34 years [IQR = 25.0-52.0]. Hypofibrinogenemia was the predominant abnormality seen, (CCA Hypofibrinogenemia: 51/193, 26 %; ROTEM hypofibrinogenemia: 65/204, 32 %). Increased CCA derangement, the presence of ROTEM coagulopathy, worsening INR, worsening FibTEM and decreasing fibrinogen concentration, were all associated with both mortality and early massive transfusion.

CONCLUSION

Clinically significant, multifaceted coagulopathy develops early in the clinical course, with hypofibrinogenemia being the predominant coagulopathy. In keeping with the ED literature, pre-hospital coagulation dysfunction was associated with mortality and early massive transfusion. Further work is required to identify strategies to identify and guide the pre-hospital management of the coagulation dysfunction seen in trauma.

Basic Principles of Rotational Thromboelastometry (ROTEM®) and the Role of ROTEM-Guided Fibrinogen Replacement Therapy in the Management of Coagulopathies

Rotational thromboelastometry (ROTEM) is a viscoelastic method, which provides a graphical and numerical representation of induced hemostasis in whole blood samples. Its ability to quickly assess the state of hemostasis is used in the management of bleeding from a variety of causes. The separate activation of particular parts of hemocoagulation in INTEM, EXTEM, and FIBTEM tests allows for a more comprehensive and faster evaluation of the missing component of hemostasis followed by targeted therapy. One of the most common cause of coagulopathy is trauma-induced coagulopathy. Fibrinogen replacement therapy by ROTEM allows for the use of a standard dosage of fibrinogen, which has been shown to be successful in preventing dilutional coagulopathy following colloid and crystalloid replacement and excessive amount of allogeneic blood transfusions. The best reflection of fibrinogen activity is observed in the FIBTEM assay, where fibrinogen replacement therapy is recommended at an MCF (maximum clot firmness) of FIBTEM < 10 mm and FIBTEM A10 < 7 mm. ROTEM also plays an important role in the diagnostic and management of inherited fibrinogen disorders. These can be manifested by bleeding complications, where changes in the MCF parameter are the most useful tool for assessing the effectiveness of fibrinogen replacement therapy. ROTEM-guided bleeding management algorithms effectively reduce the number of transfusions, healthcare costs, and complications, leading to the improvement of patient safety and overall health.

Coagulation profiles in patients with sepsis/septic shock identify mixed hypo-hypercoagulation patterns based on rotational thromboelastometry: A prospective observational study

INTRODUCTION

Sepsis-induced hemostatic disturbances are common and are associated with poor outcomes. Additionally, conventional coagulation tests (CCTs) overdiagnose hypocoagulation and cannot detect hypercoagulation and hyperfibrinolysis. The aim of this study was to describe the coagulation profiles of patients with sepsis/septic shock using rotational thromboelastometry (ROTEM) and to compare coagulation states between sepsis and septic shock groups and between surviving and non-surviving groups.

MATERIALS AND METHODS

This prospective, observational, single-center study was conducted in the intensive care unit (ICU) of the University Medical Center Ho Chi Minh City, from 6/2020-12/2021. Patients aged ≥18 years with sepsis or septic shock according to the Sepsis-3 criteria were included. ROTEM and CCTs were concurrently performed within the first 24 h of ICU admission.

RESULTS

In total, 161 patients were enrolled. Based on ROTEM, 72.7 % of patients with sepsis/septic shock had coagulation disorders, including 25.5 % hypercoagulation, 54.7 % hypocoagulation, 13.6 % mixed hypo-hypercoagulation patterns, and 18.6 % hyperfibrinolysis. A common mixed disorder subtype was characterized by prolonged initial clotting time (CT) with subsequently increased clot firmness. Fibrinogen levels and maximum clot formation (MCF)-fibtem were strongly correlated (rho = 0.73, p < 0.05). Hypocoagulation was observed more in the septic shock group than in the sepsis group. Compared to survivors, non-survivors had more prolonged CT-extem.

CONCLUSIONS

ROTEM could identify hypocoagulability, hypercoagulability, mixed hypo-hypercoagulability patterns, and hyperfibrinolysis in patients with sepsis/septic shock. Elevated MCF-fibtem and elevated fibrinogen levels were notably common and strongly correlated. The septic shock group had more hypocoagulation than the sepsis group. Lastly, non-survivors had more prolonged CT-extem than survivors.

Rotational Thromboelastometry Values After On-Pump Cardiac Surgery - A Retrospective Cohort Study

BACKGROUND

Viscoelastic coagulation monitoring is recommended for coagulation management after cardiac surgery, but optimum target values are poorly defined.

AIMS

To determine "to-be-expected" values in rotational thromboelastometry (ROTEM) after heparin reversal, to correlate ROTEM parameters with fibrinogen levels and platelet count, and to estimate the effect of hemoglobin levels on these measurements.

METHODS

We retrospectively analyzed 571 consecutive adult patients undergoing cardiac surgery with cardiopulmonary bypass from 12/2018 to 08/2020. ROTEM and conventional laboratory measurements were performed 5 to 10 minutes after protamine administration.

RESULTS

Clotting times in EXTEM, INTEM, and FIBTEM were significantly prolonged (72.6%, 96.1%, and 31.8% above reference ranges, respectively). Clot firmness parameters in EXTEM and INTEM were relevantly reduced (7.9% to 14.4% and 9.1% to 32.3% below the reference ranges, respectively). There was an excellent linear correlation of FIBTEM amplitude after 10 min (A10) and of maximal clot firmness (MCF) with fibrinogen concentrations (r = .81 and .80). Areas under receiver operating characteristic (AUROC) for identifying hypofibrinogenemia <1.5 g/L were between .80 and .87. No effect of hematocrit was observed. We also found a linear correlation of EXTEM, INTEM, and EXTEM-FIBTEM at both A10 and MCF with platelet counts (.32 to .68). The AUROCs for identifying thrombocytopenia (<100,000/μL) were .79 to .84, and were greater for A10 than for MCF measurements (P=.074, .001, and <.001, respectively).

CONCLUSIONS

"To-be-expected" ROTEM values after CPB are different from the published reference ranges. ROTEM parameters might allow for reliable estimation of fibrinogen level and platelet count without being influenced by hematocrit.

Which injured patients with moderate fibrinogen deficit need fibrinogen supplementation?

Background

In severely injured patients, fibrinogen supplementation is recommended when fibrinogenemia is < 1.5 g L⁻¹, but some teams have suggested to use higher thresholds (fibrinogenemia < 2.0 g L⁻¹ or FIBTEM clot amplitude at 5 min (A5) values < 11 mm). The goal of this study was to specify in patients with a moderate fibrinogen deficit (MFD) whether some admission characteristics would be associated with fibrinogen administration at 24 h.

Methods

Prospective analysis of retrospectively collected data from a trauma registry (01/2011–12/2019). MFD-C was defined by a fibrinogenemia 1.51–1.99 g L⁻¹ or the corresponding FIBTEM-A5 values (MFD-A5) that were determined from linear regression and ROC curve analysis. Administration of fibrinogen were described according to the following admission parameters: shock index (SI) > 1, hemoglobin level < 110 g L⁻¹ (HemoCue®), and base deficit > 5 mEq L⁻¹. Data are expressed as count (%), median [IQR].

Results

1076 patients were included in the study and 266 (27%) had MFD-C, among them, 122/266 (46%) received fibrinogen. Patients with MFD-C who received fibrinogen were more severely injured (ISS: 27 [19–36] vs. 24 [17–29]) and had more impaired vital signs (base deficit: 5.4 [3.6–7.8] vs. 3.8 [2.0–6.0]). Linear regression analysis found a positive correlation between fibrinogen level and FIBTEM-A5 (r: 0.805). For a fibrinogen level < 1.5 g L⁻¹ and < 2.0 g L⁻¹, FIBTEM-A5 thresholds were 6 mm (sensitivity 85%, specificity 83%, AUC: 0.934) and 9 mm (sensitivity 84%, specificity 69%, AUC: 0.874), respectively. MFD-A5 values (185 (27%) patients) were defined as a FIBTEM-A5 between 7 and 9 mm. More than 50% of MFD-C patients presenting a SI > 1, a hemoglobin level < 110 g L⁻¹, or a base deficit > 5.0 mEq L⁻¹ received fibrinogen. The relative risk [95% CI] for fibrinogen administration (SI > 1) were 1.39 [1.06–1.82] for MFD-C, and 2.17 [1.48–3.19] for MFD-A5. Results were not modified after adjustment on the ISS.

Conclusions

We have shown in this study an association between shock parameters and fibrinogen administration. Further studies are needed to determine how these parameters may be used to guide fibrinogen administration in trauma patients with MFD.

Congenital Afibrinogenemia and Hypofibrinogenemia: Laboratory and Genetic Testing in Rare Bleeding Disorders with Life-Threatening Clinical Manifestations and Challenging Management

Congenital fibrinogen disorders are rare pathologies of the hemostasis, comprising quantitative (afibrinogenemia, hypofibrinogenemia) and qualitative (dysfibrinogenemia and hypodysfibrinogenemia) disorders. The clinical phenotype is highly heterogeneous, being associated with bleeding, thrombosis, or absence of symptoms. Afibrinogenemia and hypofibrinogenemia are the consequence of mutations in the homozygous, heterozygous, or compound heterozygous state in one of three genes encoding the fibrinogen chains, which can affect the synthesis, assembly, intracellular processing, stability, or secretion of fibrinogen. In addition to standard coagulation tests depending on the formation of fibrin, diagnostics also includes global coagulation assays, which are effective in monitoring the management of replacement therapy. Genetic testing is a key point for confirming the clinical diagnosis. The identification of the precise genetic mutations of congenital fibrinogen disorders is of value to permit early testing of other at risk persons and better understand the correlation between clinical phenotype and genotype. Management of patients with afibrinogenemia is particularly challenging since there are no data from evidence-based medicine studies. Fibrinogen concentrate is used to treat bleeding, whereas for the treatment of thrombotic complications, administered low-molecular-weight heparin is most often. This review deals with updated information about afibrinogenemia and hypofibrinogenemia, contributing to the early diagnosis and effective treatment of these disorders.

Thromboelastometry in Neonates with Respiratory Distress Syndrome: A Pilot Study

BACKGROUND

Although respiratory distress syndrome (RDS) constitutes a postnatal risk factor for bleeding and thromboembolic events in neonates, few studies have addressed this issue. We aimed to evaluate the hemostatic profile of neonates with RDS using rotational thromboelastometry (ROTEM).

METHODS

An observational study was conducted from November 2018 to November 2020 in the NICU of General Hospital of Nikaia "Aghios Panteleimon". Preterm and term neonates with RDS hospitalized in the NICU were included and EXTEM (tissue factor-triggered extrinsic pathway), INTEM (ellagic acid activated intrinsic pathway), and FIBTEM (with platelet inhibitor cytochalasin D) assays were performed at the onset of the disease.

RESULTS

A hypocoagulable profile was noted in neonates with RDS compared to controls, expressed as significant prolongation of EXTEM CT (clotting time) and CFT (clot formation time), lower EXTEM A10 (amplitude at 10 min), MCF (maximum clot firmness), and LI60 (lysis index). Furthermore, prolongation of INTEM CFT and FIBTEM CT, and decreased INTEM and FIBTEM A10 and MCF were found in neonates with RDS. Multivariable logistic regression analysis showed that RDS is an independent factor for the recorded alterations in ROTEM variables.

CONCLUSIONS

RDS is associated with a hypocoagulable profile and greater hyperfibrinolytic potential compared to healthy neonates.

Thrombocytosis and neutrophilia associated with oxygenator failure and protamine reaction after cardiopulmonary bypass: a case report and literature review

Thrombocytosis has been feared as a source of thrombotic complications during the conduct of cardiopulmonary bypass (CPB) for patients undergoing cardiac procedures. We present a patient urgently requiring repair/replacement of three heart valves that had preexisting myelofibrosis with thrombocytosis (platelet count of 800,000 per µl) and neutrophilia (40,000 per µl). Despite achieving an activated clotting time > 500 s with heparin and antithrombin concentrate administration prior to CPB, the pump oxygenator and reservoir demonstrated significant clot just prior to restoration of the patient's circulation. The patient subsequently suffered a severe protamine reaction that was successfully managed. A review of the literature of similar patients and the relevant cellular and biochemical mechanisms in this setting are presented, with potential therapeutic approaches to prevent such complications noted.

First-Line Administration of Fibrinogen Concentrate in the Bleeding Trauma Patient: Searching for Effective Dosages and Optimal Post-Treatment Levels Limiting Massive Transfusion-Further Results of the RETIC Study

Fibrinogen supplementation is recommended for treatment of severe trauma hemorrhage. However, required dosages and aimed for post-treatment fibrinogen levels remain a matter of discussion. Within the published RETIC study, adult patients suffering trauma-induced coagulopathy were randomly assigned to receive fibrinogen concentrate (FC) as first-line (n = 50) or crossover rescue (n = 20) therapy. Depending on bodyweight, a single dose of 3, 4, 5, or 6 g FC was administered and repeated if necessary (FibA10 < 9 mm). The dose-dependent response (changes in plasma fibrinogen and FibA10) was analyzed. Receiver operating characteristics (ROC) analysis regarding the need for massive transfusion and correlation analyses regarding fibrinogen concentrations and polymerization were performed. Median FC single doses amounted to 62.5 (57 to 66.66) mg·kg⁻¹. One FC single-dose sufficiently corrected fibrinogen and FibA10 (median fibrinogen 213 mg·dL⁻¹, median FibA10 11 mm) only in patients with baseline fibrinogen above 100 mg·dL⁻¹ and FibA10 above 5 mm, repeated dosing was required in patients with lower baseline fibrinogen/FibA10. Fibrinogen increased by 83 or 107 mg·dL⁻¹ and FibA10 by 4 or 4.5 mm after single or double dose of FC, respectively. ROC curve analysis revealed post-treatment fibrinogen levels under 204.5 mg·dL⁻¹ to predict the need for massive transfusion (AUC 0.652; specificity: 0.667; sensitivity: 0.688). Baseline fibrinogen/FibA10 levels should be considered for FC dosing as only sufficiently corrected post-treatment levels limit transfusion requirements.

Minimal invasive extracorporeal circulation preserves coagulation integrity

INTRODUCTION

Coagulopathy after cardiac surgery is a serious multifactorial complication that results in postoperative bleeding requiring transfusion of red blood cells and procoagulant products. Use of cardiopulmonary bypass represents the major contributing factor affecting coagulation. We sought to prospectively investigate the effect of contemporary minimal invasive extracorporeal circulation (MiECC) on coagulation parameters using point-of-care (POC) rotational thromboelastometry and the relation to postoperative bleeding.

METHODS

Patients undergoing elective cardiac surgery on MiECC were prospectively recruited. Anticoagulation strategy was based on individualized heparin management and heparin level-guided protamine titration. Rotational thromboelastometry testing was performed before induction of anesthesia and after aortic cross-clamp release. A strict POC-guided transfusion protocol was implemented. The primary endpoint was the assessment of viscoelastic properties of the coagulating blood at the end of surgery compared to preoperative values and the relation to postoperative bleeding and 24-hour transfusion requirements.

RESULTS

Fifty patients were included in the study with a significant proportion having complex surgery. Thirteen patients (26%) required blood transfusion (mean rate: 0.5 ± 1 units per patient), 5/50 (10%) received coagulation factors while no patient received fresh frozen plasma, platelets or fibrinogen. Thromboelastometry analysis showed that the major derangement was CT EXTEM > 100 seconds in 28/50 (56%) and A10 EXTEM < 40 mm in one (2%) patient without clinical significance. Platelet function was preserved throughout surgery. A10-FIBTEM was found predictive of postoperative bleeding at 12 hours.

CONCLUSIONS

MiECC preserves clot quality throughout surgery acting in both key determinants of clot strength; fibrinogen and platelets. This is clinically translated into minimal postoperative bleeding and restricted use of blood products and coagulation factors.