Revisiting Hartert's 1962 Calculation of the Physical Constants of Thrombelastography.

Thrombelastography (TEG)/thromboelastometry (ROTEM) devices measure viscoelastic clot strength as clot amplitude (A). Transformation of clot amplitude into clot elasticity (E with TEG; CE with ROTEM) is sometimes necessary (eg, when calculating platelet component of the clot). With TEG, clot amplitude is commonly transformed into shear modulus (G; expressed in Pa or dyn/cm) as follows: G = (5000 × A)/(100 - A).

Assessing the Methodology for Calculating Platelet Contribution to Clot Strength (Platelet Component) in Thromboelastometry and Thrombelastography.

The viscoelastic properties of blood clot have been studied most commonly using thrombelastography (TEG) and thromboelastometry (ROTEM). ROTEM-based bleeding treatment algorithms recommend administering platelets to patients with low EXTEM clot strength (e.g.

Over 50 Years of Fibrinogen Concentrate.

March 2013 represented the 50th anniversary of the first license granted for a fibrinogen concentrate. In this review, we look at the history of bleeding management that led to the development of fibrinogen concentrate, discuss its current use, and consider future developments for this product.

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

Background: 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.

The effectiveness of different functional fibrinogen polymerization assays in eliminating platelet contribution to clot strength in thromboelastometry.

Background: Viscoelastic tests such as functional fibrinogen polymerization assays (FFPAs) in thrombelastography (TEG®) or thromboelastometry (ROTEM®) measure clot elasticity under platelet inhibition. Incomplete platelet inhibition influences maximum clot firmness (MCF) of FFPAs. We compared the ability of existing and newly developed FFPAs to eliminate the platelet contribution to clot strength.

Thromboelastometric maximum clot firmness in platelet-free plasma is influenced by the assay used.

Background: Viscoelastic tests such as functional fibrinogen polymerization assays (FFPAs) in thrombelastography (TEG(®)) or thromboelastometry (ROTEM(®)) measure the elasticity of extrinsically activated clotting under conditions of platelet inhibition. There are no reports on whether components of the FFPAs have any effects on fibrin polymerization, aside from the effects of platelet inhibition.

Methods: Using various platelet-free plasma (PFP) preparations, we compared the extrinsically activated EXTEM thromboelastometric assay with 3 FFPAs: FIBTEM, FIBTEM PLUS, and the Functional Fibrinogen Test(®) (FFTEG).

Effects of fibrinogen concentrate as first-line therapy during major aortic replacement surgery: a randomized, placebo-controlled trial.

Background: Fibrinogen is suggested to play an important role in managing major bleeding. However, clinical evidence regarding the effect of fibrinogen concentrate (derived from human plasma) on transfusion is limited. The authors assessed whether fibrinogen concentrate can reduce blood transfusion when given as intraoperative, targeted, first-line hemostatic therapy in bleeding patients undergoing aortic replacement surgery.

Comparison of whole blood fibrin-based clot tests in thrombelastography and thromboelastometry.

Background: Fibrin-based clot firmness is measured as maximum amplitude (MA) in the functional fibrinogen (FF) thrombelastographic assay and maximum clot firmness (MCF) in the FIBTEM thromboelastometric assay. Differences between the assays/devices may be clinically significant. Our objective was to compare clot firmness parameters through standard (FF on a thrombelastography device [TEG®]; FIBTEM on a thromboelastometry device [ROTEM®]) and crossover (FF on ROTEM®; FIBTEM on TEG®) analyses.

Transfusion in trauma: thromboelastometry-guided coagulation factor concentrate-based therapy versus standard fresh frozen plasma-based therapy.

Introduction: Thromboelastometry (TEM)-guided haemostatic therapy with fibrinogen concentrate and prothrombin complex concentrate (PCC) in trauma patients may reduce the need for transfusion of red blood cells (RBC) or platelet concentrate, compared with fresh frozen plasma (FFP)-based haemostatic therapy.

Methods: This retrospective analysis compared patients from the Salzburg Trauma Centre (Salzburg, Austria) treated with fibrinogen concentrate and/or PCC, but no FFP (fibrinogen-PCC group, n = 80), and patients from the TraumaRegister DGU receiving ≥ 2 units of FFP, but no fibrinogen concentrate/PCC (FFP group, n = 601). Inclusion criteria were: age 18-70 years, base deficit at admission ≥ 2 mmol/L, injury severity score (ISS) ≥ 16, abbreviated injury scale for thorax and/or abdomen and/or extremity ≥ 3, and for head/neck < 5.

A comparison of fibrinogen measurement methods with fibrin clot elasticity assessed by thromboelastometry, before and after administration of fibrinogen concentrate in cardiac surgery patients.

Background: Fibrinogen concentrate administration can be guided by measuring fibrinogen concentration or quality of the fibrin-based clot. This study compared different fibrinogen concentration measurement methods with maximum clot firmness (MCF) of the fibrin clot, assessed by thromboelastometry (FIBTEM), in 33 cardiovascular surgery patients receiving fibrinogen concentrate for hemostatic therapy.

Study Design And Methods: Blood samples were collected after cardiopulmonary bypass (CPB) and after fibrinogen concentrate administration.