Figure 1

Technique of Thrombelastography (reprinted with permission from Haemoscope Corporation, Niles, IL). (a) A torsion wire suspending a pin is immersed in a cuvette filled with blood. A clot forms while the cuvette is rotated 45°, causing the pin to rotate depending on the clot strength. A signal is than discharged to the transducer that reflects the continuity of the clotting process. The subsequent tracing (b) corresponds to the entire coagulation process from thrombin generation to fibrinolysis. The R value, which is recorded as TEG-ACT in the rapid TEG specimen, is a reflection of enzymatic clotting factor activation. The K value is the interval from the TEG-ACT to a fixed level of clot firmness, reflecting thrombin's cleavage of soluble fibrinogen. The α is the angle between the tangent line drawn from the horizontal base line to the beginning of the crosslinking process. The MA, or maximum amplitude, measures the end result of maximal platelet-fibrin interaction, and the LY 30 is the percent lysis which occurs at 30 minutes from the initiation of the process, which is also calculated as the EPL, or estimated percent lysis.