What the Sigma? Exploring the Change From Single to Dual Anti-Platelet ROTEM on the FIBTEM to Clauss Fibrinogen...

The Clauss fibrinogen (CF) assay is the clinical standard for detecting hypofibrinogenaemia in traumatic intracranial haemorrhage (TICH). This assay, however, is time-intensive limiting rapid coagulopathy management. FIBTEM, a module of the rotational thromboelastometry (ROTEM) Sigma device, alternatively provides a rapid point-of-care assessment of fibrin contribution to clot firmness. In many centres, FIBTEM is used as a surrogate for CF. Recently, the FIBTEM cartridge has been modified to include tirofiban in addition to cytochalasin, shifting from a single to dual anti-platelet formulation. The impact of this change on the established FIBTEM-CF relationship remains uncertain, and it is unclear if FIBTEM thresholds typically thought to corroborate with reduced CF remain valid.

We conducted a retrospective observational cohort study between February 2022 and 2025, evaluating the relationship between FIBTEM and CF before and after the cartridge modification at our institute. Eligible participants were patients with TICH and a Glasgow Coma Scale ≤ 14 who underwent FIBTEM and CF testing on simultaneously drawn samples.

The linear relationship between FIBTEM and CF was not influenced by cartridge type (p = 0.82). Diagnostic performance (AUROCs: 0.94 versus 0.95; p = 0.71) and the optimised cut-point (FIBTEM A5 $\le$ 8 mm) for the detection of hypofibrinogenaemia were also comparable between the single and dual anti-platelet systems.

Similar relationships between FIBTEM and CF were observed for single and dual anti-platelet FIBTEM systems in TICH. Thresholds for fibrinogen replacement may be generalisable between single and dual anti-platelet FIBTEM systems; however, external validation is necessary.