These include thromboelastography (TEG) and thromboelastometry (TEM)
In TEG the cup rotates
In RO (ROtational) TEM the pin rotates
They are not directly comparable as they use different activators. Common activators include kaolin. “Rapid TEG” includes kaolin + tissue factor.
R time
Reaction time. Time from start of test to amplitude of 2mm.
Represents clotting time. Suggests presence of an anticoagulant or factor deficiency. Treat with plasma.
K time
Clot formation time. Time between 2mm and 20mm amplitude. Dependent on fibrinogen or platelets.
Alpha angle
Angle between 2mm and 20mm points
Maximum amplitude
Represents peak clot strength. Mostly (80%) dependent on platelets, but also fibrinogen. Treat with platelets and / or cryoprecipitate. Some machines include a IIb/IIIa platelet inhibitor where MA will be due only to fibrinogen activity.
CL30 / CL60
Percentage reduction in amplitude at 30 or 60 mins respectively. High LY30 / 60 suggests hyperfibrinolysis e.g. presence of TPA. Can treat with TXA.
Evidence for use
May provide cost benefit in cardiac surgery and liver transplantation.
Potentially reduce transfusions in obstetric haemorrhages.