Fibrinogen Concentration In Whole Blood Research Articles

Paper Diagnostic for Direct Measurement of Fibrinogen Concentration in Whole Blood.

The ability to diagnose and treat critically bleeding patients can save more than 2 million lives a year. Diagnosing hypofibrinogenemia is essential in these patients. Recently, with the development of new handheld diagnostics, fibrinogen concentration can be measured rapidly at the point of care. However, these diagnostics can only work with plasma and hence need blood cells to be separated before use. In this study, we demonstrate a handheld fibrinogen diagnostic that works with whole blood. The test works by (1) forming a premixed droplet of a whole blood sample and thrombin solution on a solid surface, (2) allowing it to clot, and (3) dropping a paper strip on top. The further that blood moves down the strip, the lower the fibrinogen concentration. The diagnostic can easily measure plasma fibrinogen concentrations below 1.6 g/L for blood samples with hematocrits between 40 and 50%. Furthermore, diluting blood samples not only increases the test's sensitivity but also eliminates the effect of hematocrit and thrombin inhibitors. The test can be completed in 3-4 min, making it suitable for diagnosing early hypofibrinogenemia and allowing for fibrinogen replacement therapy in critically bleeding patients.

The contribution of the individual blood elements to the variability of thromboelastographic measures.

Thromboelastography (TEG) is widely advocated as a rapid method for obtaining critical blood coagulation data to guide resuscitation, but the method suffers well-known limits in sensitivity, repeatability, and interpretability. Mixtures of fresh human blood components were prepared that represent the range of blood element concentrations seen in health and disease and after injury. These mixtures were tested in a TEG device after kaolin, tissue factor and phospholipid, or tissue factor and phospholipid with abciximab activation. The results were measured as reproducibility and nonlinear effects in regression analysis and evaluated for interpretability. Clot strength was associated with increased platelet (PLT) content and plasma fibrinogen concentration and content. Increasing hematocrit (Hct) reduced while increasing PLT or plasma concentration increased TEG clot strength. The abciximab dose used to block PLT activity did not fully inhibit the PLT contribution to clot strength. Clot strength is logarithmically correlated in the absence and linearly correlated to PLT concentration in the presence of abciximab. TEG clot strength with or without abciximab is dependent on Hct, PLT, and plasma (fibrinogen) concentrations in complex patterns. Interpretation of TEG variables is limited without knowledge of the concentration of the blood components present. When "normal" TEG values are known for a certain PLT-plasma-red blood cell concentration, the assay can be used to assess PLT and plasma function in coagulation. The TEG "functional fibrinogen" assay should be used only as a gross estimate of the fibrinogen concentration in whole blood.

Comparison of a qualitative canine C-reactive protein test to a quantitative test and traditional markers of inflammation - Short communication.

Qualitative tests for C-reactive protein (CRP) are available for use in dogs, and provide a rapid in-house method of detecting acute inflammation. The aim of this study was to compare results from a qualitative CRP lateral flow test (Teco CRP FASTest) to those obtained from a quantitative CRP ELISA and to traditional methods of detecting inflammation, including total leukocyte and neutrophil numbers, presence of immature neutrophils and a left shift, presence or absence of toxic changes in neutrophils and plasma fibrinogen concentration in whole blood and serum samples collected from 113 client-owned dogs. More dogs had CRP FASTest positive results than had quantitatively increased CRP (ELISA) or increases in traditional methods used for measuring inflammation. Few dogs had increases in markers of inflammation but no elevated CRP. The qualitative CRP FASTest was found to be a sensitive test for detecting increased CRP concentration and was positive more frequently than were traditional markers of inflammation.

Rapid measurement of fibrinogen concentration in whole blood using a steel ball coagulometer.

Fibrinogen plays a key role in hemostasis and is the first coagulation factor to reach critical levels in bleeding patients. Current European guidelines on the management of traumatic or perioperative bleeding recommend fibrinogen supplementation at specific threshold levels. Whole blood viscoelastic tests provide fast evaluation of fibrin deficits. Fast measurement of plasma fibrinogen concentration is not yet available. We investigated a method to rapidly determine whole blood fibrinogen concentration using standard Clauss assays and a steel ball coagulometer and provide an estimate of the "plasma-equivalent" fibrinogen concentration within minutes by adjustment of the measured whole blood fibrinogen concentration with a quickly measureable hemoglobin-derived hematocrit. The feasibility of this approach was tested with a Clauss assay using multiple porcine fresh blood samples obtained during in vivo bleeding, hemodilution, and after treatment with hemostatic therapy. Two different Clauss assays were then tested using multiple human volunteers' blood samples diluted in vitro and supplemented with fibrinogen concentrate. Comparative measurements with fibrin-based thromboelastometry tests were performed. Regression and Bland-Altman analyses of derived "plasma-equivalent" fibrinogen and measured plasma fibrinogen concentration was excellent in porcine and human blood samples, especially in the ranges relevant to traumatic or perioperative bleeding. Fast whole blood fibrinogen measurements could be considered as an alternative to plasma fibrinogen measurement for acute bleeding management in trauma and perioperative care settings. Further studies are needed to prove this concept and determine the turnaround times for its clinical application in emergency departments and operating theaters.

High haematocrit in cyanotic congenital heart disease affects how fibrinogen activity is determined by rotational thromboelastometry

Viscoelastometry enables rapid evaluation of coagulopathy in settings such as cardiac surgery but may be influenced by red cell concentration. In order to study the effects of supra-physiological red cell concentrations on viscoelastometry, we compared ROTEM® viscoelastometry and plasma coagulation assay results in high haematocrit (HCT; 0.55-0.76 L/L) blood from patients with cyanotic congenital heart disease (CCHD), and in model high HCT blood (HCT 0.45-0.70 L/L). High HCT blood from CCHD patients (median HCT 0.66 L/L) displayed prolonged clot initiation in the EXTEM® test compared to controls and reduced maximum clot firmness (MCF) in the EXTEM (median 51 mm vs 64 mm in controls) and FIBTEM® (7 mm vs 14 mm) tests. The plasma fibrinogen (Clauss; CF) was similar in CCHD blood to controls (median 2.94 g/L vs 2.49) but the whole blood fibrinogen concentration (WBFC) was reduced (1.27 g/L vs 1.58). The FIBTEM MCF correlated linearly with the CF (r(2)=0.68; p<0.0001) and WBFC (r(2)=0.65; p<0.0001) in control blood but this relationship was maintained only with WBFC in CCHD blood. Model high HCT blood showed abnormal ROTEM test results that were similar to CCHD blood, including reduced FIBTEM MCF (14 mm with HCT 0.32-0.44 vs 6mm with HCT 0.63-0.70). The ROTEM results were HCT dependent but independent of plasma clotting times and fibrinogen concentration. Supra-physiologic HCT causes abnormal ROTEM test results consistent with increased dilution of fibrinogen and coagulation factors in whole blood by red cells. High HCT should be considered during interpretation of ROTEM test results in clinical settings.