Low FIBTEM amplitude in neurotrauma: True plasma fibrinogen depletion or functional fibrin activity reduction?

BACKGROUND

FIBTEM, a component of rotational thromboelastometry, assesses the functional contribution of fibrin to clot formation. Notably, impaired fibrin function using FIBTEM may be observed despite normal plasma fibrinogen levels measured by the Clauss assay. The clinical implications of such isolated functional deficits are poorly understood in traumatic intracranial hemorrhage (TICH) and are the focus of this brief report.

METHODS

From February 2022 to July 2023, we conducted a single-center retrospective study of patients with TICH and Glasgow Coma Scale score of ≤14. All participants had paired FIBTEM and Clauss fibrinogen levels from simultaneously drawn samples. Patients were grouped as follows: (1) FIBTEM-A5 >10 mm, (2) FIBTEM-A5 ≤10 mm with Clauss fibrinogen >2 g/L (isolated fibrin dysfunction), and (3) FIBTEM-A5 ≤10 mm with fibrinogen ≤2 g/L (true fibrinogen deficiency [TD]). Rates of progressive hemorrhagic injury and mortality were compared using univariate and multivariable analyses.

RESULTS

Of 73 included patients, 37 (51%) had reduced FIBTEM-A5; among these, 12 (32%) experienced TD. Mortality occurred in 7 of 12 TD patients (58%), 11 of 36 (31%) with FIBTEM-A5 >10 mm, and 6 of 25 (24%) with isolated fibrin dysfunction. Progressive hemorrhagic injury occurred in 6 of 9 TD patients (66%), 2 of 26 (8%) with FIBTEM-A5 >10 mm, and 9 of 23 (39%) with isolated fibrin dysfunction. In multivariate analysis, TD was associated with a 4.5-fold increase in the log odds of progressive hemorrhagic injury (95% confidence interval, 1.5-7.4), while isolated fibrin dysfunction was associated with a 3.2-fold increase (95% confidence interval, 1.0-5.4). No significant associations with mortality were observed.

CONCLUSION

In TICH, low FIBTEM-A5 may reflect either fibrinogen deficiency or impaired fibrin function. Progressive hemorrhagic injury is increased in both of these phenotypes. Further research is needed to validate these findings and to guide the optimal clinical response to low FIBTEM-A5 in neurotrauma.

LEVEL OF EVIDENCE: Prognostic and Epidemiologic; Level IV.