Global hemostasis testing thromboelastography: old technology, new applications

Thromboelastography (TEG) as a method of assessing global hemostatic and fibrinolytic function has existed for more than 60 years. Improvements in TEG technology have led to increased reliability and thus increased usage. The TEG has been used primarily in the settings of liver transplant and cardiac surgery, with proven utility for monitoring hemostatic and fibrinolytic derangements. In recent years, indications for TEG testing have expanded to include managing extracorporeal membrane oxygenation (ECMO) therapy, assessing bleeding of unclear etiology, and assessing hypercoagulable states. In addition, TEG platelet mapping has been utilized to monitor antiplatelet therapy. Correlation between TEG platelet mapping and other platelet function tests such as the PFA-100 or platelet aggregation studies, however, has not been evaluated fully for clinical outcomes, and results may not be comparable. In general, the advantages of the TEG include evaluation of global hemostatic function using whole blood, a quick turn-around-time, the possibility of both point-of-care-testing and performance in central laboratories, the ability to detect hyperfibrinolysis, monitoring therapy with recombinant activated factor VII, and detection of low factor XIII activity. Potential applications include polycythemia and dysfibrinogenemia. Disadvantages of TEG include a relatively high coefficient of variation, poorly standardized methodologies, and limitations on specimen stability of native whole blood samples. In the pediatric setting, an additional advantage of the TEG is a relatively small sample volume, but a disadvantage is the difference in normal ranges between infants, especially newborns, and adults. In summary, TEG is an old concept with new applications that may provide a unique perspective on global hemostasis in various clinical settings.