Thromb Haemostasis
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Multicenter Study Clinical Trial
Multicenter retrospective study on the utilization of FEIBA in France in patients with factor VIII and factor IX inhibitors. French FEIBA Study Group. Factor Eight Bypassing Activity.
Factor VIII or factor IX replacement is frequently impossible in inhibitor-developing hemophiliacs, because of the level of the inhibitor titer. Activated prothrombin complex concentrates are one of the available options to treat the bleeding episodes in such patients. However, the efficacy of these products and the associated thrombogenic risk, particularly in prolonged administration such as employed during surgeries, are important concerns for hemophilia care providers. ⋯ An anamnestic response after the administration of FEIBA was noted in 31.5% of cases. This study points out the main features of the use of FEIBA in France, and particularly the low HIV seroprevalence in the patients treated. The good efficacy and the excellent tolerance still confer to this product a place to consider in the therapeutic options for the treatment of inhibitor-developing hemophiliacs or in acquired hemophilia.
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Disseminated intravascular coagulation (DIC) may lead to severe thrombotic or hemorrhagic complications. The present work was undertaken to study the effect of interleukin 6 (IL-6) on variations of key coagulation and fibrinolytic parameters in plasma in a baboon model of experimental DIC induced by injection of factor Xa and phospholipids at dosages leading to partial (48%) or complete fibrinogen depletion. Transient increases of D-dimer, fibrinopeptide A, thrombin-antithrombin and the activated partial thromboplastin time were observed. ⋯ Plasminogen activator inhibitor type 1 (PAI-1) concentrations did not change after low dose Xa/phospholipids, but increased eightfold after high dose Xa/phospholipids, IL-6 pretreatment induced within 8 h a twentyfold increase of PAI-1 but no further increase was observed after injection of factor Xa/phospholipids. Thus, in vivo thrombin generation leads to dynamic modifications of the coagulation and fibrinolytic systems. The principal effect of IL-6 is a more rapid normalization of overall coagulation tests, due to normalization of fibrinogen, and an increased t-PA release response which is partially counteracted by increased PAI-1 concentrations.
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Comparative Study Clinical Trial
In vitro clot lysis as a potential indicator of thrombus resistance to fibrinolysis--study in healthy subjects and correlation with blood fibrinolytic parameters.
Using an in vitro model of clot lysis, the individual response to a pharmacological concentration of recombinant tissue plasminogen activator (rt-PA) and the influence on this response of the physiological variations of blood parameters known to interfere with the fibrinolytic/thrombolytic process were investigated in 103 healthy donors. 125I-fibrin labelled blood clots were submersed in autologous plasma, supplemented with 500 ng/ml of rt-PA or solvent, and the degree of lysis was determined after 3 h of incubation at 37 degrees C. Baseline plasma levels of t-PA, plasminogen activator inhibitor 1 (PAI-1), plasminogen, alpha 2-antiplasmin, fibrinogen, lipoprotein (a), thrombomodulin and von Willebrand factor as well as platelet and leukocyte count and clot retraction were also determined in each donor. rt-PA-induced clot lysis varied over a wide range (28-75%) and was significantly related to endogenous t-PA, PAI-1, plasminogen (p < 0.001) and age (p < 0.01). Multivariate analysis indicated that both PAI-1 antigen and plasminogen independently predicted low response to rt-PA. ⋯ The observation that neutralization of PAI-1 by specific antibodies, both in plasma and within the clot, did not potentiate clot lysis indicates that the inhibitor, including the platelet-derived form, is insufficient to attenuate the thrombolytic activity of a pharmacological concentration of rt-PA and that its elevation, similarly to the elevation of plasminogen, is not the cause of clot resistance but rather a coincident finding. It is concluded that the in vitro response of blood clots to rt-PA is poorly influenced by the physiological variations of the examined parameters and that factors other than those evaluated in this study interfere with clot dissolution by rt-PA. In vitro clot lysis test might help to identify patients who may be resistant to thrombolytic therapy.
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Haemorrhage, including intracranial bleeding, is a common, potentially lethal complication of warfarin therapy and rapid and complete reversal of anticoagulation may be life-saving. Fresh frozen plasma (FFP) and vitamin K are most frequently administered. Because of the variable content of vitamin K-dependent clotting factors in FFP, and the effects of dilution, the efficacy of this approach is open to doubt. ⋯ In FFP treated patients, poorer responses were also observed for each of the other vitamin K-dependent clotting factors but these were less marked than for factor IX, which was present in low concentrations in some batches of FFP. Thus, haemostatically effective levels of factor IX cannot be achieved, in most instances, by the conventional use of FFP in patients requiring reversal of their anticoagulant therapy. Clotting factor concentrates are the only effective option where complete and immediate correction of the coagulation defect is indicated in orally anticoagulated patients with life or limb-threatening haemorrhage.
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The haemostatic system and the use of heparin during cardiopulmonary bypass (CPB) have been studied extensively in adults but not in children. Results from adult trials cannot be extrapolated to children because of age-dependent physiologic differences in haemostasis. We studied 22 consecutive paediatric patients who underwent CPB at The Hospital for Sick Children, Toronto. ⋯ However, low plasma concentrations of heparin (< 2.0 units/ml in 45% of patients) during CPB were likely a major contributing etiology. ACT values showed a poor correlation (r = 0.38) with heparin concentrations likely due to concurrent haemodilution of haemostatic factors, activation of haemostatic system, hypothermia and activation of platelets. In conclusion, CPB in paediatric patients causes global decreases of components of the coagulation and fibrinolytic systems, primarily by haemodilution and secondarily by consumption.