Influences of argatroban on five fibrinogen assays

Guideline for diagnosis and management of congenital dysfibrinogenemia

INTRODUCTION

Congenital dysfibrinogenemia (CD) is characterized by dysfunction induced by an abnormal fibrinogen molecule structure that results in blood coagulation dysfunction. The clinical manifestations of CD patients are asymptomatic, bleeding and thrombosis. The majority of patient are asymptomatic. However, the single fibrinogen detection method is easy to cause missed diagnosis or misdiagnosis of CD patients. The treatment strategies of CD patients with different clinical manifestations are also different.

METHODS

Combing the existing experimental diagnosis technology, literature and our research results, a simple and practical CD diagnostic criteria was proposed. And based on the relevant literature and existing treatment guidelines, more comprehensive treatment recommendations are summarized.

RESULTS

In this new criteria, combination Clauss method and PT derived method was proposed to detect fibrinogen and its ratio was used to diagnose for CD. Diagnosis also needs to be combined the clinical manifestations, family investigation and genetic testing. According to different clinical manifestation (bleeding, thrombosis or asymptomatic), treatment methods and strategies are different. The treatment of CD patients should consider the patient's personal and family history of bleeding or thrombosis. Treatment of thrombosis and pregnancy may be more challenging. The risk of bleeding and thrombosis should be evaluated and balanced at all times during clinical treatment. These detailed treatment recommendations can provide reference for patients with different clinical manifestations of CD.

CONCLUSIONS

The new CD diagnosis criteria and comprehensive treatment recommendations can effectively improve the diagnosis and treatment of CD.

International council for standardisation in haematology recommendations on fibrinogen assays, thrombin clotting time and related tests in the investigation of bleeding disorders

This guidance was prepared on behalf of the International Council for Standardisation in Haematology (ICSH) by an international working group of clinicians and scientists. The document focuses on tests and assays used for the assessment of fibrinogen function, particularly in the scenario of bleeding disorders. Thrombin clotting time (TT) is used as a screening test in some laboratories and also has some utility when direct anticoagulants are in use. The Clauss fibrinogen assay remains the method of choice for the assessment of fibrinogen function, but there are some situations where the results may be misleading. Prothrombin time derived fibrinogen assays are frequently used, but should be interpreted with caution; the results are not interchangeable between different methods and fibrinogen can be overestimated in certain clinical scenarios. Viscoelastic point of care methods may be helpful in emergency situations, while Reptilase time (and similar tests) are useful combined with TT in distinguishing heparin contamination of samples (i.e., if an incorrect blood draw is suspected) and the presence of direct thrombin inhibitors. Fibrinogen antigen assays should be used in the investigation of functional fibrinogen abnormalities; fibrinogen antigen and genetic testing are recommended in the confirmation of congenital fibrinogen disorders. The following recommendations for fibrinogen function assessment are based on published literature and expert opinion and should supplement local regulations and standards.

Anticoagulation Management during Extracorporeal Membrane Oxygenation-A Mini-Review

Extracorporeal membrane oxygenation (ECMO) has been established as a life-saving technique for patients with the most severe forms of respiratory or cardiac failure. It can, however, be associated with severe complications. Anticoagulation therapy is required to prevent ECMO circuit thrombosis. It is, however, associated with an increased risk of hemocoagulation disorders. Thus, safe anticoagulation is a cornerstone of ECMO therapy. The most frequently used anticoagulant is unfractionated heparin, which can, however, cause significant adverse effects. Novel drugs (e.g., argatroban and bivalirudin) may be superior to heparin in the better predictability of their effects, functioning independently of antithrombin, inhibiting thrombin bound to fibrin, and eliminating heparin-induced thrombocytopenia. It is also necessary to keep in mind that hemocoagulation tests are not specific, and their results, used for setting up the dosage, can be biased by many factors. The knowledge of the advantages and disadvantages of particular drugs, limitations of particular tests, and individualization are cornerstones of prevention against critical events, such as life-threatening bleeding or acute oxygenator failure followed by life-threatening hypoxemia and hemodynamic deterioration. This paper describes the effects of anticoagulant drugs used in ECMO and their monitoring, highlighting specific conditions and factors that might influence coagulation and anticoagulation measurements.

Comparison of Fibrinogen Concentrations Determined by the Clauss Method with Prothrombin-Derived Measurements on an Automated Coagulometer

Background

This research aims to compare fibrinogen results, obtained from the Clauss and PT-derived method on the Cobas t511 analyzer, in patients with specific categories of disease. A second aim was to determine the reference range for these 2 methods.

Methods

We retrospectively compared fibrinogen concentrations of 914 patients obtained by the Clauss and PT-derived methods on the Cobas t511 coagulation analyzer from the laboratory information system. Fibrinogen data was segregated into a healthy outpatient population and those populations with possible fibrinogen abnormalities including pregnancy, chronic illness, liver disease, heart and vascular diseases, and clinical suspicion of COVID-19. All data were analyzed using Passing–Bablok regression and Bland–Altman analysis. Reference ranges were determined from fibrinogen results of the healthy outpatient population who presented for a clinic check-up.

Results

All fibrinogen results were grouped and compared according to fibrinogen values (low, normal, and high), international normalized ratio (INR) values (<1.2, 1.2–2.0, and >2.0), and diagnosis. There were statistically significant positive correlations in all groups (P < 0.05), except for low fibrinogen values (P = 0.96). Results with INR value <1.2 had the highest correlation between 2 methods.

Conclusion

The PT-derived method can be used alone in the Cobas t511 analyzer, especially in patients with an INR <1.2. Reported new reference ranges of the PT-derived method could help to determine and compare the clinical significance of fibrinogen methods. Further studies must be focused on the conditions in which PT-derived fibrinogen results should be directed to the Clauss test.

GFHT Proposals On The Practical Use Of Argatroban - With Specifics Regarding Vaccine-Induced Immune Thrombotic Thrombocytopaenia (VITT)

Argatroban is a direct anti-IIa (thrombin) anticoagulant, administered as a continuous intravenous infusion; it has been approved in many countries for the anticoagulant management of heparin-induced thrombocytopaenia (HIT). Argatroban was recently proposed as the non-heparin anticoagulant of choice for the management of patients diagnosed with Vaccine-induced Immune Thrombotic Thrombocytopaenia (VITT). Immunoglobulins are also promptly intravenously administered in order to rapidly improve platelet count; concomitant therapy with steroids is also often considered. An ad hoc committee of the French Working Group on Haemostasis and Thrombosis members has worked on updated and detailed proposals regarding the management of anticoagulation with argatroban, based on previously released guidance for HIT, and adapted for VITT. In case of VITT, the initial dose to be preferred is 1.0 µg x kg^-1 x min^-1, with further dose-adjustments based on iterative and frequent clinical and laboratory assessments. It is strongly advised to involve a health practitioner experienced in the management of difficult cases in haemostasis. The first laboratory assessment should be performed 4 hours after the initiation of argatroban infusion, with further controls at 2-4-hour intervals until steady state, and at least once daily thereafter. Importantly, full anticoagulation should be rapidly achieved in case of widespread thrombosis. Cerebral vein thrombosis (which is typical of VITT) should not call for an overly cautious anticoagulation scheme. Argatroban administration requires baseline laboratory assessment and should rely on an anti-IIa assay to derive argatroban plasma levels using a dedicated calibration, with a target range between 0.5 and 1.5 µg/mL. Target argatroban plasma levels can be refined based on meticulous appraisal of risk factors for bleeding and thrombosis, on frequent reassessments of clinical status with appropriate vascular imaging, and on the changes in daily platelet counts. Regarding the use of aPTT, baseline value and possible causes for alterations of the clotting time must be taken into account. Specifically, in case of VITT, an aPTT ratio (patient's / mean normal clotting time) between 1.5 and 2.5 is suggested, to be refined according to the sensitivity of the reagent to the effect of a direct thrombin inhibitor. The sole use of aPTT is discouraged: one has to resort to a periodical check with an anti-IIa assay at least, with the help of a specialised laboratory if necessary. Dose modifications should proceed in a stepwise manner with 0.1 to 0.2 µg x kg^-1 x min^-1 up- or downward changes, taking into account the initial dose, laboratory results, and the whole individual setting. Nomograms are available to adjust the infusion rate. Haemoglobin level, platelet count, fibrinogen plasma level and liver tests should be periodically checked, depending on the clinical status, the more so when unstable.

Clean version: Electrospun fibrinogen scaffolds from discarded blood for wound healing

Immediate reutilization of discarded blood from surgery has not received much attention, leading to the waste of a large amount of autologous blood. We used a concentration gradient and high-voltage electrospinning technology to immediately prepare a scaffold material with high biological activity but without immunogenicity from autologous waste blood collected during surgery. Here, we fabricated and characterized a 90 mg/mL group, 110 mg/mL group, and 130 mg/mL group of fibrinogen (FBG) scaffolds. Analyses revealed that the FBG scaffolds had good film-forming properties and a clear fiber structure. in vitro cell viability experiments confirmed that the cells showed an increasing trend with increasing FBG concentrations. The cells grew well in the scaffold material and secreted more cell matrix. When human bone mesenchymal stem cells (hBMSCs) were cocultured with the scaffold material, the hBMSCs expressed osteogenic and chondrogenic biomarkers. The cellular scaffold complexes from the 3 groups were implanted in four full-thickness round wounds (Φ12 mm) on the dorsal back of each rat, the 130 mg/mL group showed a 90% reduction in wound size and the data compared to other groups were better at 14 day. These results suggest that electrospinning technology-based FBG scaffold materials derived from autologous waste blood may become an ideal tissue engineering scaffold and can be immediately used for autologous hemostasis, anti-adhesion films, and wound dressing in surgery.