Stability of coagulation parameters in plasma samples at room temperature after one freeze/thaw cycle

International audienceIntroduction Sample freezing is a part of routine laboratory tasks because some coagulation parameters are analysed in batches to optimize reagent consumption. The coagulation parameter stability in fresh and frozen samples has been described, but data are scarcer after thawing. This study objective was to determine the stability of the main coagulation parameters (from blood withdrawn on siliconized CTAD tubes and double-centrifuged) after one freeze/thaw cycle to generate procedures for appropriate handling, storage and testing. Methods Prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen, D-dimers, clotting factors (F), protein C, protein S, antithrombin, lupus anticoagulant (LA)-sensitive aPTT and diluted-Russel's viper venom time (dRVVT) were assessed in 60 plasma samples (n=30, normal range and n=30, outside the normal range). Thirty samples from anticoagulated patients [unfractionated heparin (UFH), low-molecular weight heparin (LMWH), apixaban or rivaroxaban] were assessed using specific anticoagulant assays. Frozen samples were thawed, and assays were performed at 15 min, 2, 4 and 6 h after thawing. The coagulation parameter stability was assessed with the method of rejection limit. Results: After thawing, aPTT, PT, fibrinogen, D-dimers, FII, FV, FX, FIX, FXI, FXII, PC and UFH anti-Xa activity remained stable for at least 6 h, FVII for 5 h, PS, AT, dRVVT screen assay and LMWH anti-Xa activity for 4 h, and LA-sensitive aPTT and apixaban-specific anti-Xa activity for 3 h. FVIII, dRVVT confirm assay and rivaroxaban specific anti-Xa activity were stable for 2 h. Conclusion These results suggest that sample stability for some haemostasis assays is limited after thawing

Anesthesiology

Centrifugation-based autotransfusion devices only salvage red blood cells while platelets are removed. The same™ device (Smart Autotransfusion for ME; i-SEP, France) is an innovative filtration-based autotransfusion device able to salvage both red blood cells and platelets. The authors tested the hypothesis that this new device could allow a red blood cell recovery exceeding 80% with a posttreatment hematocrit exceeding 40%, and would remove more than 90% of heparin and 75% of free hemoglobin. Adults undergoing on-pump elective cardiac surgery were included in a noncomparative multicenter trial. The device was used intraoperatively to treat shed and residual cardiopulmonary bypass blood. The primary outcome was a composite of cell recovery performance, assessed in the device by red blood cell recovery and posttreatment hematocrit, and of biologic safety assessed in the device by the washout of heparin and free hemoglobin expressed as removal ratios. Secondary outcomes included platelet recovery and function and adverse events (clinical and device-related adverse events) up to 30 days after surgery. The study included 50 patients, of whom 18 (35%) underwent isolated coronary artery bypass graft, 26 (52%) valve surgery, and 6 (12%) aortic root surgery. The median red blood cell recovery per cycle was 86.1% (25th percentile to 75th percentile interquartile range, 80.8 to 91.6) with posttreatment hematocrit of 41.8% (39.7 to 44.2). Removal ratios for heparin and free hemoglobin were 98.9% (98.2 to 99.7) and 94.6% (92.7 to 96.6), respectively. No adverse device effect was reported. Median platelet recovery was 52.4% (44.2 to 60.1), with a posttreatment concentration of 116 (93 to 146) · 109/l. Platelet activation state and function, evaluated by flow cytometry, were found to be unaltered by the device. In this first-in-human study, the same™ device was able to simultaneously recover and wash both platelets and red blood cells. Compared with preclinical evaluations, the device achieved a higher platelet recovery of 52% with minimal platelet activation while maintaining platelet ability to be activated in vitro

GFHT proposals on the practical use of argatroban - With specifics regarding vaccine-induced immune thrombotic thrombocytopaenia (VITT)

International audienceArgatroban 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 × kg(-1) × 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 h after the initiation of argatroban infusion, with further controls at 2-4-h 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 × kg(-1) × 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

Is there a role for the laboratory monitoring in the management of specific antidotes of direct oral anticoagulants?

International audienceGiven the growing number of patients receiving direct oral anticoagulant (DOAC), patients requiring rapid neutralization is also increasing in case of major bleedings or urgent surgery/procedures. Idarucizumab is commercialized as a specific antidote to dabigatran while andexanet alfa has gained the Food and Drug Administration and the European Medicines Agency approval as an oral anti-factor Xa inhibitors antidote. Other antidotes or hemostatic agents are still under preclinical or clinical development, the most advanced being ciraparantag. DOAC plasma levels measurement allows to appropriately select patient for antidote administration and may prevent unnecessary prescription of expensive molecules in some acute clinical settings. However, these tests might be inconclusive after some antidote administration, namely andexanet alfa and ciraparantag. The benefit of laboratory monitoring following DOAC reversal remains unclear. Here, we sought to provide an overview of the key studies evaluating the safety and efficacy of DOAC reversal using the most developed/commercialized specific antidotes, to discuss the potential role of the laboratory monitoring in the management of patients receiving DOAC specific antidotes and to highlight the areas that deserve further investigations in order to establish the exact role of laboratory monitoring in the appropriate management of DOAC specific antidotes

Collagen-induced arthritis and imiquimod-induced psoriasis develop independently of interleukin-33

International audienc

Idiopathic purpura fulminans associated with anti-protein S antibodies in children: a multicenter case series and systematic review

International audienceAbstract Idiopathic purpura fulminans (IPF) is a rare but severe prothrombotic coagulation disorder that can occur after chickenpox or human herpesvirus 6 (HHV-6) infection. IPF leads to an autoantibody-mediated decrease in the plasma concentration of protein S. We conducted a retrospective multicenter study involving patients with IPF from 13 French pediatric centers and a systematic review of cases in published literature. Eighteen patients were included in our case series, and 34 patients were included as literature review cases. The median age was 4.9 years, and the diagnostic delay after the first signs of viral infection was 7 days. The lower limbs were involved in 49 patients (94%) with typical lesions. In all, 41 patients (78%) had a recent history of varicella-zoster virus infection, and 7 patients (14%) had been infected by HHV-6. Most of the patients received heparin (n = 51; 98%) and fresh frozen plasma transfusions (n = 41; 79%); other treatment options were immunoglobulin infusion, platelet transfusion, corticosteroid therapy, plasmapheresis, and coagulation regulator concentrate infusion. The antithrombin level and platelet count at diagnosis seemed to be associated with severe complications. Given the rarity of this disease, the creation of a prospective international registry is required to consolidate these findings

GFHT proposals on the practical use of argatroban — With specifics regarding vaccine-induced immune thrombotic thrombocytopaenia (VITT)

International audienc