Thromboelastography

It is a test mainly used in surgery and anesthesiology, although increasingly used in resuscitations in emergency departments, intensive care units, and labor and delivery suites.

More common tests of blood coagulation include prothrombin time (PT) and partial thromboplastin time (aPTT) which measure coagulation factor function, but TEG also can assess platelet function, clot strength, and fibrinolysis which these other tests cannot.

A small sample of blood is taken from the selected person and rotated gently through 4º 45', six times a minute, to imitate sluggish venous flow and activate coagulation.

The angle is the tangent of the curve made as the K is reached and offers similar information to K. The MA is a reflection of clot strength.

There are some studies which suggest that an elevated G-value is associated with a hypercoagulable state and therefore increases the risk for venous thromboembolic disease.

A disposable pin is attached to a shaft which is connected with a thin spring (the equivalent to Hartert's torsion wire in thrombelastography) and slowly oscillates back and forth.

[6][7] There are several types of assays that can be run using TEG: Standard (kaolin), RapidTEG, heparinase, Functional Fibrinogen and PlateletMapping.

In instances where a patient develops bleeding due to recurrent coagulopathy (usually shortly after arrival to the ICU), the heparinase TEG can help quickly discern patients who can be treated with additional dosing of protamine versus those who need to be taken back to the operating room for re-exploration.

Because the R value on the TEG represents the time it takes for clot formation to start, it is a reflection of coagulation factor activity.

[8] The iTACTIC trial showed no difference in outcomes in trauma patients with massive hemorrhage managed with conventional coagulation tests compared to viscoelastic assays.

However, the traumatic brain injury subgroup showed slightly better survival in the TEG/ROTEM group with a “very low” quality assessment by the GRADE system.

[10] In elective surgery there was a decreased need for blood products (platelets and plasma) and reduced operating room length of stay as well as duration of intensive care admission and bleeding rates; mortality was not affected.