OC 77.2 - Thrombelastography-estimated functional fibrinogen function in healthy volunteers, ESRD, and trauma: inaccurate when most needed

Background: Thrombelastography(TEG) is used for rapid assessment of functional fibrinogen to guide hemostatic therapy in patients at risk for severe hemorrhage, and to suspect hypercoagulability.

Aims: To determine the correlation between TEG functional fibrinogen(FLEV), Rapid and Kaolin TEG angle and maximum amplitude(MA) with conventional Clauss fibrinogen assay in healthy volunteers(HV), patients with end-stage renal disease(ESRD), and trauma patients at risk for trauma induced coagulopathy(TIC).

Methods: We obtained consent from 120 HV(50% female, median age=30years), and from 52 patients with ESRD at the time of their arterio-venous fistula procedure(56% female, median age=58years). Trauma patients at risk for TIC (n=173, 22.5% female, median age=33years) had blood samples obtained upon admission under a waiver of consent. Pearson correlations between Clauss fibrinogen and TEG values were calculated for the three cohorts and for subgroups of trauma patients with hypofibrinogenemia (Clauss fibrinogen < 150mg/dl) with/without shock (Systolic blood pressure < 90mmHg or lactate>5mmol/l or base deficit>10mEq/l) as well as ESRD patients with hyperfibrinogenemia(Clauss fibrinogen>500mg/dl).

Results: Correlations for the three cohorts and trauma subgroups are summarized in the table. Rapid TEG-MA, Kaolin TEG-MA, and TEG-FLEV(Figure) had moderate(0.50-0.70) correlations for all groups. Only Kaolin TEG MA in ESRD patients had a correlation>0.70. Clauss fibrinogen values corresponded to higher FLEV value(ratios:1:1.3-1:1.8). Among trauma patients with hypofibrinogenemia, all TEG values had much lower correlations, regardless of whether they were in shock(Table,Figure). Inclusion of second/third degree polynomials did not improve the correlations. No patients in the ESRD and HV groups had hypofibrinogenemia. For ESRD patients with hyperfibrinogenemia, all correlations, except for Kaolin TEG-MA, decreased(Table,Figure). Platelet counts were normal.

Conclusion(s): TEG derived values used to estimate functional fibrinogen have poor correlation with Clauss fibrinogen in patients with hypo/hyperfibrinogenemia. Thus, resuscitation when hypofibrinogenemia is suspected should not rely on TEG values. Furthermore, TEG is suboptimal to assess the role of hyperfibrinogenemia in adverse clotting.