Citrate storage affects Thrombelastograph® analysis

Background: Thrombelastograph® analysis (TEG®) is used to evaluate blood coagulation. Ideally, whole blood is immediately processed. If impossible, blood may be citrated and assessed after recalcification. No data describe the effect of such treatment and storage on TEG® parameters. Metbods: Three studies were performed in 90 surgical patients. In 30 patients, blood was citrated (1:10, 0.129 M) and recalcified (20 μl 2 M CaCl 2 to 340 μ1 citrated blood), and TEG® was performed with native blood and after recalcification after 0, 15, and 30 min of citrate storage. In another 30 patients, TEG® was performed with citrated blood recalcified immediately and after 1-72 h storage. In a third study, thrombin-antithrombin complex, prothrombin fragment 1+2, and β-thromboglobulin were measured (using enzyme-linked immunoabsorbant assay tests) at corresponding time points. Data were compared using repeated-measures analysis of variance and post hoc paired t tests. Results: TEG® parameters were different in recalcified citrated blood compared with native blood (P < 0.05) and changed significantly during 30-min (P < 0.025) and 72-h (P < 0.001) citrate storage. TEG® parameters measured between 1 and 8 h of citrate storage were stable. Thrombin-antithrombin complex and prothrombin fragment 1+2 values were not elevated in native blood. After 30 min of citrate storage a gradual thrombin activation was observed, as evidenced by increasing thrombin-antithrombin complex and prothrombin fragment 1+2 values (P < 0.05). -Thromboglobulin level was increased after 2 and 8 h of citrate storage (P < 0.01). Conclusions: Analysis of native blood yields the most reliable TEG® results. Should immediate TEG® processing not be possible, citrated blood may be used if recalcified after 1-8 h.