BACKGROUND: Thromboelastography (TEG) is used to diagnose perturbations in clot formation and lysis that are characteristic of acute traumatic coagulopathy. With novel functional fibrinogen (FF) TEG, fibrin- and platelet-based contributions to clot formation can be elucidated to tailor resuscitation and thromboprophylaxis. We sought to describe the longitudinal contributions of fibrinogen and platelets to clot strength after injury, hypothesizing that low levels of FF and a low contribution of fibrinogen to clot strength on admission would be associated with coagulopathy, increased transfusion requirements, and worse outcomes.
METHODS: A total of 603 longitudinal plasma samples were prospectively collected from 251 critically injured patients at a single Level 1 trauma center from 0 hour to 120 hours. TEG maximal amplitude (MA), FF MA, FF levels, von Clauss fibrinogen, and standard coagulation measures were performed in parallel. Percentage contributions of FF (%MAFF) and platelets (%MAplatelets) were calculated as each MA divided by overall kaolin TEG MA.
RESULTS: Coagulopathic patients (international normalized ratio ≥ 1.3) had significantly lower admission %MAFF than noncoagulopathic patients (24.7% vs. 31.2%, p < 0.05). Patients requiring plasma transfusion had a significantly lower admission %MAFF (26.6% vs. 30.6%, p < 0.05). Higher admission %MAFF was predictive of reduced mortality (hazard ratio, 0.815, p < 0.001). %MAplatelets was higher than %MAFF at all time points, decreased over time, and stabilized at 72 hours (69.4% at 0 hour, 56.2% at 72 hours). In contrast, %MAFF increased over time and stabilized at 72 hours (30.6% at 0 hour, 43.8% at 72 hours).
CONCLUSION: FF TEG affords differentiation of fibrin- versus platelet-based clot dynamics. Coagulopathy and plasma transfusion were associated with a lower %MAFF. Despite this importance of fibrinogen, platelets had a greater contribution to clot strength at all time points after injury. This suggests that attention to these relative contributions should guide resuscitation and thromboprophylaxis and that antiplatelet therapy may be of underrecognized importance to thromboprophylaxis after trauma.
LEVEL OF EVIDENCE: Prognostic study, level III.
From the Department of Surgery, San Francisco General Hospital, University of California, San Francisco, San Francisco, California.
Submitted: July 31, 2013, Revised: October 28, 2013, Accepted: November 4, 2013.
This study was presented at the 72nd annual meeting of the American Association for the Surgery of Trauma, September 18–21, 2013, in San Francisco, California.
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Address for reprints: Lucy Z Kornblith, MD, Department of Surgery, Ward 3A San Francisco General Hospital 1001 Potrero Ave, Room 3C-38 San Francisco, CA 94110; email: firstname.lastname@example.org.