Thrombosis research
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Thrombosis research · Jan 2008
ReviewModeling the action of factor VIIa in dilutional coagulopathy.
Dilutional coagulopathy is observed in patients who have lost blood and had the blood volume replaced with components that do not have plasma procoagulants and anticoagulants. Since both procoagulant and anticoagulant mechanisms contribute to total thrombin generation, it is not clear whether the procoagulant or anticoagulant effects will dominate when both are decreased. Decreasing antithrombin levels leads to increasing thrombin generation in ex vivo models. ⋯ Limited clinical data suggest that factor VIIa has been useful in controlling intractable bleeding in some cases of dilutional coagulopathy. Preliminary data suggest that factor VIIa activation of factors X and IX on activated platelets enhances thrombin generation significantly in a model of dilutional coagulopathy. This may suggest a mechanism to account for the efficacy of factor VIIa in reducing blood loss in some settings of dilutional coagulopathy.
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Thrombosis research · Jan 2008
ReviewWarfarin-reversal: results of a phase III study with pasteurised, nanofiltrated prothrombin complex concentrate.
Bleeding can be a major problem in patients on oral anticoagulation therapy. Beriplex P/N is a prothrombin complex concentrate (PCC) that has been developed for the rapid reversal of anticoagulation in patients requiring immediate haemostatic control. Beriplex P/N contains high concentrations of the coagulation factors II, VII, IX and X, together with the inhibitors protein C and protein S, and it can be rapidly prepared and administered at an infusion rate of up to 8.0 mL/min. ⋯ There were no adverse events related to the rapid rate of infusion and, of the 8 serious adverse events reported; only 1 was regarded as being possibly related to treatment. No virus transmission was observed and changes in thrombogenicity markers were found to be transient and did not correspond to any clinically observed thromboembolic events. In conclusion, Beriplex P/N is an effective and well-tolerated therapy for rapid, complete and predictable reversal of anticoagulation in patients with acute bleeding or requiring emergency surgery.
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Thrombosis research · Jan 2008
ReviewWarfarin-induced bleeding complications - clinical presentation and therapeutic options.
Acute bleeding during oral anticoagulant therapy is a major challenge in medicine -with millions of patients receiving oral anticoagulant therapy worldwide, the frequency of severe bleeding episodes ranges from 2% to 13%, according to clinical trial data. The major risk associated with the use of oral anticoagulants is haemorrhage, which might be severe or even life-threatening. Treatment decisions for the reversal of oral anti-coagulation (OAC) depend on factors such as urgency of the situation, as determined by the international normalised ratios (INR), location and seventy of bleeding, and indication for anticoagulation. ⋯ In addition, PCC is associated with a more rapid normalisation of the INR and a better clinical outcome due to the balanced ratio of four vitamin-K-dependent clotting factors plus the coagulation inhibitors protein C and Protein S. PCC products containing four factors are the preferred option for the emergency reversal of OAC, according to some clinical treatment guidelines. Other advantages of PCC over FFP include smaller infusion volumes, no blood group testing and virus-inactivated blood product.
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Thrombosis research · Jan 2008
Comparative StudyUsefulness of high-concentration calcium chloride solution for correction of activated partial thromboplastin time (APTT) in patients with high-hematocrit value.
Pseudoprolongation of activated partial thromboplastin time (APTT) is a serious problem in anticoagulation therapy for patients with high hematocrit, such as cyanotic congenital heart diseases. APTT pseudoprolongation occurs when APTT assay is performed using routinely used vacuum sampling tubes containing citrate. Because the plasma fraction is small in high-hematocrit blood, the prescribed volume of citrate would be excessive for APTT assay, resulting in prolongation of clotting or APTT pseudoprolongation. CLSI--The Clinical and Laboratory Standards Institute (formerly NCCLS) method is the established method to correct the pseudoprolongation. However, the CLSI method needs repeated blood drawings and time-consuming, complicate procedures. Thus, alternative simple method is desired. ⋯ High-calcium chloride solution method is useful to correct APTT pseudoprolongation. Because of the simplicity and the need of a single blood drawing, this method would reduce the burdens of not only patients but also clinical laboratory.
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Thrombosis research · Jan 2008
Influence of polymorphonuclear leukocytes on the plasma clot formation as evaluated by thromboelastometry (ROTEM).
It has been emphasized that polymorphonuclear leukocytes (PMN) participate in the regulation of coagulation. However, the mechanisms of action are not clear. Besides a procoagulant activity, anticoagulant or fibrinolytic properties are attributed to these cells. To explore their global effect, we have studied their involvement in the clot formation with thromboelastometry, which gives global view over the clotting process, in particular on the structure of the clot and on the kinetic of its formation. ⋯ The procoagulant activity of resting PMN was demonstrated as the initiation of fibrin formation with PMN-RP was significantly faster compared with both PRP and PPP. The kinetic of plasma clotting was remarkably improved with PMN-RP compared with PPP. However, the clot with PMN-RP had the same poor viscoelastical properties as PPP. Thromboelastometry gives a new point of view in the involvement of PMN in coagulation, in the absence of any PMN pre-activation. Their impact was centred on the kinetic and the facilitation of the clot formation.