Impact of fibrinogen concentration in severely ill patients on mechanical properties of whole blood clots
ABSTRACT Fibrinogen concentration influences mechanical and functional properties of the clot. The purpose of the present study was to identify threshold concentrations of fibrinogen resulting in relevant changes in whole blood clot elastic modulus and platelet contractile force, as well as plasma prothrombin time and activated partial thromboplastin time. We measured clot elastic modulus, platelet contractile force, and other hemostasis parameters in whole blood samples from 552 patients admitted to a surgical intensive care unit. Platelet contractile force and clot elastic modulus were measured using the Hemodyne apparatus. Fibrinogen levels were between less than 0.10 and 9.44 g/l, with a mean of 2.41 g/l. Mean platelet count was 203 x 10(9) l(-1), with a range of 16 x 10(9) l(-1) to 682 x 10(9) l(-1). High levels of fibrinogen result in improved mechanical stability and improved interaction of platelets with the fibrin network. Clot elastic modulus and platelet contractile force are correlated positively with plasma fibrinogen concentration. However, there was no threshold concentration or ceiling effect concerning the mechanical properties of the clots. In contrast, clotting time assays such as prothrombin time, thrombin time, or activated partial thromboplastin time are influenced by the fibrinogen concentration only at levels below 1 g/l. In linear regression analysis, clot elastic modulus was mainly influenced by fibrinogen concentration (F = 185.4, P < 0.0001), whereas platelet contractile force was influenced by fibrinogen (F = 197.0, P < 0.0001) and platelet count (F = 104.7, P < 0.0001). The present data show that 1 g/l is a threshold fibrinogen concentration for an effect on coagulation assays such as prothrombin time, thrombin time, or activated partial thromboplastin time, but increasing fibrinogen concentrations above this level results in further continuous improvement of mechanical properties of the whole blood clot.
- Thrombosis Research 01/2011; 127(1):65-6. DOI:10.1016/j.thromres.2010.04.018 · 2.43 Impact Factor
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ABSTRACT: Diagnostic point of care testing based on thrombelastometry with the aim to fully understand the overall changes in global haemostasis during the perioperative phase is today performed in several operating theatres. Therapeutic measures are based on these laboratory results. Within the scope of a pro and contra outline of the journal this paper comment, why point of care diagnostic solely based on laboratory testing using the ROTEM is not recommendable. On the other hand the author values the thrombelastometry as a supplementary supportive method used directly by haemostasis specialists or in a tight cooperation with such skilled specialists.ains · Anästhesiologie · Intensivmedizin 05/2011; 46(5):318-22. DOI:10.1055/s-0031-1277973 · 0.34 Impact Factor
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ABSTRACT: Coagulation management requires the balancing of different components that contribute to clot formation. These components include the interactions between platelets, procoagulant, anticoagulant, and fibrinolytic factors. The cause of bleeding or thrombotic events is often multifactorial; however, the tests clinicians most frequently use to assess hemostasis do not reflect the complexity of the coagulation system. The paucity of global measurements of hemostasis has resulted in either an empirical or a one-size-fits-all approach to treatment. In contrast, thromboelastography is a test that monitors the different phases of clot formation and lysis, providing the clinician with a tool for making informed therapeutic decisions. This review provides an overview of thromboelastography in the management of hypocoagulable and hypercoagulable conditions.Seminars in Thrombosis and Hemostasis 10/2010; 36(7):699-706. DOI:10.1055/s-0030-1265286 · 3.69 Impact Factor