Seminars in thrombosis and hemostasis
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Semin. Thromb. Hemost. · Dec 2004
ReviewPeriprocedural management of anticoagulation in patients on extended warfarin therapy.
Patients receiving chronic anticoagulation therapy pose a clinical challenge when therapy needs to be interrupted for surgical or invasive procedures. Maintaining anticoagulation places them at risk of serious bleeding complications, whereas discontinuing anticoagulation puts them at risk of thromboembolic complications. ⋯ Currently, there is little consensus on appropriate perioperative management of patients on long-term warfarin therapy. This article is an attempt to bring together all the available data on periprocedural bridging to assess the available options for patients undergoing surgical procedures and to provide a rationale for using low-molecular-weight heparins (LMWHs) while individualizing the risks versus benefits in a given patient population.
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Over recent years, the use of portable coagulation monitors for prothrombin time-International Normalized Ratio (PT-INR) testing has been gaining popularity. Their advantages over traditional methods of monitoring include ease of use, short test duration, faster turnaround time for dosage changes, increased patient convenience by eliminating the need to go to the laboratory for venipuncture, and increased patient-provider interaction. Portable coagulation monitors for PT-INR testing are currently used in various settings, such as anticoagulation clinics, physician offices, at the patient's bedside in hospital wards, and independently by patients at home. ⋯ Various point of care (POC) coagulation monitors have been developed, and many models are commercially available in the United States. Because technology differs among the various devices, accuracy and precision need to be determined for individual devices. The various devices cannot be used interchangeably, and individual device performance cannot be generalized.
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Semin. Thromb. Hemost. · Jun 2004
Review Randomized Controlled Trial Clinical TrialRecombinant platelet factor 4 for heparin neutralization.
Protamine sulfate has been used for many years to reverse the effects of unfractionated heparin, but it can cause hemodynamic changes and other serious side effects. Platelet factor 4 (PF4) is a naturally occurring protein synthesized in megakaryocytes and eventually stored in the alpha granules of platelets for later release. Although the complete physiologic role of PF4 is unknown, it is highly effective for the neutralization of heparin anticoagulation. ⋯ Serial measurements of rPF4 levels showed a monophasic elimination pattern with a serum half-life of 25.5 +/- 13.5 minutes that was independent of dose administered. A randomized and blinded trial comparing rPF4 to protamine confirmed the safety and effectiveness of rPF4. Although rPF4 was initially being evaluated as a clinical alternative to protamine, it is not currently being developed for general clinical use.
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Semin. Thromb. Hemost. · Feb 2004
ReviewHeparin and low-molecular-weight heparin therapy for venous thromboembolism: will unfractionated heparin survive?
Recent improvements in clinical trials methodology and the use of accurate objective tests to detect venous thromboembolism (VTE) have made it possible to carry out a series of randomized trials to evaluate various treatments for VTE. The results of these trials have resolved many of the uncertainties a clinician confronts in selecting the appropriate course of anticoagulant therapy. These trials have shown that the intensity of both initial heparin treatment and long-term anticoagulant therapy must be sufficient to prevent unacceptable rates of recurrence of VTE. ⋯ Treatment with low-molecular-weight heparin (LMWH), which does not require monitoring or dose finding, has largely replaced unfractionated heparin for the initial management of VTE. Efficacy in terms of recurrent VTE or extension of thrombus has been at least as good with LMWH as unfractionated heparin and there is evidence that the incidence of major bleeding, heparin-induced thrombocytopenia, and osteoporosis are less with LMWH as compared with unfractionated heparin. Although unfractionated heparin may survive as a treatment option for acute VTE, its use has been largely supplanted by LMWH.
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Semin. Thromb. Hemost. · Oct 2003
ReviewHyperviscosity in polycythemia vera and other red cell abnormalities.
Thrombosis is a major cause of mortality and morbidity in polycythemia vera (PV). The wide range of thrombotic events reflects the complex picture in PV. There are multiple factors involved in thrombogenesis in this disease, including increased hematocrit, thrombocytosis, impaired fibrinolytic activity, platelet activation, leukocyte activation, endothelial damage, interactions between platelets and endothelium, various modalities of therapy, and increased in whole-blood viscosity. ⋯ Thrombotic complications can also occur in both arteries and veins and manifest as stroke, myocardial infarction, deep vein thrombosis, or pulmonary embolism. The hemodynamic principle is aptly applied in the management of PV. The most important objective is the reduction of the patient's hematocrit.