BACKGROUND: Trauma patients are at risk of developing an acute coagulopathy of trauma (ACT) related to tissue injury, shock, and hemodilution. ACT is incompletely understood, but is similar to disseminated intravascular coagulation (DIC) and is associated with poor outcome.
STUDY DESIGN AND METHODS: Thrombin generation assays were used to evaluate plasma hemostasis in 42 trauma patients, 25 normal subjects, and 45 patients on warfarin and in laboratory-prepared factor reduced plasma. RESULTS: Prolonged prothrombin time (PT), more than 18 seconds, or an international normalized ratio of greater than 1.5 was present in 15 trauma patients indicating possible ACT. Native thrombin generation (no activator added, contact activation blocked) showed that Trauma with ACT patients had lag times 68% shorter and peak thrombin generation threefold higher than normal patients indicating the presence of circulating procoagulants capable of initiating coagulation systemically. Trauma patients had lower platelet counts and fibrinogen and Factor (F)II levels putting them at increased risk of bleeding. In laboratory-prepared isolated factor-reduced samples and in patients with vitamin K-dependent factor deficiency due to warfarin, thrombin generation decreased in direct proportion to FII levels. In contrast, in diluted plasma and in trauma patients with reduced factor levels, thrombin generation was increased and associated with slower inhibition of thrombin generation (prolonged termination time) and decreased antithrombin levels (43% of normal in Trauma with ACT).
CONCLUSIONS: Thrombin generation studies indicate that Trauma with ACT patients show dysregulated hemostasis characterized by excessive non-wound-related thrombin generation due to a combination of circulating procoagulants capable of activating coagulation systemically and reduced inhibitor levels allowing systemic thrombin generation to continue once started.
Dunbar NM, Chandler WL.
From the Department of Laboratory Medicine, University of Washington, Seattle, Washington
Showing posts with label bovine thrombin. Show all posts
Showing posts with label bovine thrombin. Show all posts
Wednesday
Assessment of thrombin generation: useful or hype?
School of Human Life Sciences, University of Tasmania, Tasmania, Australia. Murray.
Thrombin plays an important role in hemostasis through its multiple functions across blood coagulation, platelet activation, and fibrinolysis. The measurement of thrombin generation is therefore viewed as a potentially useful test that could be applied to the screening, monitoring, and/or diagnosis of hemostatic abnormalities. Indeed, advances in thrombin generation assays have created significant interest and debate as to whether they may provide a more physiologically relevant testing system than do traditional coagulation tests.
A variety of thrombin generation assays, including commercially available systems, have been investigated for their correlation with hypocoagulable and hypercoagulable states. Although there is an extensive body of literature that has investigated the application of thrombin generation assays, some limitations remain. These include poor standardization of reagents and methods and a lack of large prospective studies that demonstrate clear relationships between thrombin generation with bleeding and thrombosis phenotypes, as well as with monitoring anticoagulation.
Whether thrombin generation assays become more "useful" than "hype" will require well-designed, large, prospective multicenter trials using standardized methods
Thrombin plays an important role in hemostasis through its multiple functions across blood coagulation, platelet activation, and fibrinolysis. The measurement of thrombin generation is therefore viewed as a potentially useful test that could be applied to the screening, monitoring, and/or diagnosis of hemostatic abnormalities. Indeed, advances in thrombin generation assays have created significant interest and debate as to whether they may provide a more physiologically relevant testing system than do traditional coagulation tests.
A variety of thrombin generation assays, including commercially available systems, have been investigated for their correlation with hypocoagulable and hypercoagulable states. Although there is an extensive body of literature that has investigated the application of thrombin generation assays, some limitations remain. These include poor standardization of reagents and methods and a lack of large prospective studies that demonstrate clear relationships between thrombin generation with bleeding and thrombosis phenotypes, as well as with monitoring anticoagulation.
Whether thrombin generation assays become more "useful" than "hype" will require well-designed, large, prospective multicenter trials using standardized methods
Friday
A Phase 3, Randomized, Double-Blind Comparative Study of the Efficacy and Safety of Topical Recombinant Human Thrombin and Bovine Thrombin in Surgical
Background
Plasma-derived bovine thrombin is used as a topical agent to improve surgical hemostasis, but development of antibodies to bovine hemostatic proteins has been associated with increased bleeding and thrombotic complications. Recombinant human thrombin could reduce the risk of these complications.
Study Design
The objective of this randomized, double-blind, comparative trial was to compare the efficacy, safety, and antigenicity of recombinant human thrombin (rhThrombin) and bovine thrombin as adjuncts to hemostasis in liver resection, spine, peripheral arterial bypass, and dialysis access surgery. Blinded study drug was applied topically to bleeding sites with an absorbable gelatin sponge. The primary efficacy end point was time to hemostasis, summarized as the incidence of hemostasis within 10 minutes. Safety analyses were conducted for 1 month after operation, and the development of antibodies to rhThrombin or to the bovine product was evaluated.
Results
Four hundred one patients completed this trial. Hemostasis was achieved at the time-to-hemostasis evaluation site within 10 minutes in 95% of patients in each treatment group. Overall complications, including operative mortality, adverse events, and laboratory abnormalities, were similar between groups. Forty-three (21.5%) patients receiving bovine thrombin developed antibodies to the product; three patients (1.5%; p < 0.0001) in the rhThrombin group developed antibodies to rhThrombin. None of the three patients who developed antirhThrombin antibodies had abnormal coagulation laboratory results or bleeding, thromboembolic, or hypersensitivity events.
Conclusions
Results of this trial suggest that rhThrombin has comparable efficacy, a similar safety profile, and is considerably less immunogenic than bovine thrombin when used for surgical hemostasis.
Plasma-derived bovine thrombin is used as a topical agent to improve surgical hemostasis, but development of antibodies to bovine hemostatic proteins has been associated with increased bleeding and thrombotic complications. Recombinant human thrombin could reduce the risk of these complications.
Study Design
The objective of this randomized, double-blind, comparative trial was to compare the efficacy, safety, and antigenicity of recombinant human thrombin (rhThrombin) and bovine thrombin as adjuncts to hemostasis in liver resection, spine, peripheral arterial bypass, and dialysis access surgery. Blinded study drug was applied topically to bleeding sites with an absorbable gelatin sponge. The primary efficacy end point was time to hemostasis, summarized as the incidence of hemostasis within 10 minutes. Safety analyses were conducted for 1 month after operation, and the development of antibodies to rhThrombin or to the bovine product was evaluated.
Results
Four hundred one patients completed this trial. Hemostasis was achieved at the time-to-hemostasis evaluation site within 10 minutes in 95% of patients in each treatment group. Overall complications, including operative mortality, adverse events, and laboratory abnormalities, were similar between groups. Forty-three (21.5%) patients receiving bovine thrombin developed antibodies to the product; three patients (1.5%; p < 0.0001) in the rhThrombin group developed antibodies to rhThrombin. None of the three patients who developed antirhThrombin antibodies had abnormal coagulation laboratory results or bleeding, thromboembolic, or hypersensitivity events.
Conclusions
Results of this trial suggest that rhThrombin has comparable efficacy, a similar safety profile, and is considerably less immunogenic than bovine thrombin when used for surgical hemostasis.
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