Table 7 Overview of ROTEM ® parameters

1

NATEM (= ‘classic thromboelastometry’)

Only recalcification agent.

None – coagulation is activated by contact with the surface of the measurement container.

Produces a curve representing ‘whole blood coagulation’.

2

EXTEM

Tissue factor and phospholipids.

Activates the extrinsic pathway.

CT corresponds to PT. Curve represents clot formation, stability and fibrinolysis resulting from the extrinsic pathway.

3

INTEM

Ellagic acid and phospholipids.

Activates the intrinsic pathway.

CT corresponds to aPTT.

4

FIBTEM®

As EXTEM, plus cytochalasin D.

Cytochalasin D inhibits platelets.

Allows qualitative assessment of fibrinogen levels.

5

APTEM

As EXTEM, plus aprotinin.

Aprotinin inhibits plasmin and therefore fibrinolysis.

Comparing EXTEM and APTEM can rule in or out hyperfibrinolysis.

6

HEPTEM®

As INTEM, plus heparinase I.

Degrades heparin.

A comparison of HEPTEM® and INTEM indicates how much coagulation is affected by heparin.

CT (Clotting time)

Gives information about the kinetics of fibrin formation and clot development. Prolongation of CT may be a result of heparin or coagulation factor deficiency.

CFT (Clotting formation time)

Gives information about the rate of clot formation. It is calculated as the interval between the onset of coagulation, arbitrarily defined as when the amplitude is 2mm, and the curve reaching an amplitude of 20mm. A prolonged CFT but normal MCF indicates a clot polymerization disorder.

AA (Alpha angle)

Indicates the rate at which a solid clot forms. Both CFT and alpha angle are influenced by coagulation factors, platelet count and/or function and fXIII.

MCF (Maximum clot firmness)

Shows the maximal strength and stability of the fibrin and platelet clot. A reduced MCF and normal CFT suggest lack of fibrinogen and/or platelets.