Variability in viscoelastic haemostatic assay in major haemorrhage protocols: A unified approach or mixed signals?

Abstract

Background and objectives: Viscoelastic haemostatic assays (VHA) are part of patient blood management (PBM) for bleeding, associated with reduced transfusions. This study reviewed all major haemorrhage protocols (MHPs) using VHA in Queensland, Australia, and assessed variability.

Methods: VHA platforms in Queensland Health include rotational thromboelastometry (ROTEM® Sigma) and thromboelastography (TEG 6 s). PBM guidelines were searched for VHA-guided MHPs. Outcomes included viscoelastic thresholds and transfusion recommendations.

Results: Nineteen hospitals used VHA: sixteen with ROTEM and three with TEG. Among hospitals with ROTEM, fibrinolysis was assessed first in 13 algorithms, primarily using FIBTEM flat-line (n = 6) or ML >5% (n = 5). Fibrinogen thresholds were FIBTEM A5 <10 mm (n = 15) and <12 mm (n = 1). Platelet thresholds included EXTEM A5 <25 mm (n = 2) or EXTEM A5 <35 mm (n = 6) as isolated criteria, and EXTEM A5 <35 mm combined with FIBTEM A5 >10 mm (n = 9) as combined criterion. Coagulation factor thresholds were EXTEM CT >90 s (n = 13), EXTEM CT >80 s (n = 2) and INTEM CT ≥240 s (n = 1). TEG algorithms used CFF MA/A10 <15 mm (n = 3), <10 mm and <5 mm (n = 1). Platelet thresholds: CRT MA <50 mm (n = 3), and <25 mm (n = 1). Coagulation factor thresholds: CK R >9 min (n = 2) and CKH R >10 min (n = 1). Fibrinolysis: CRT LY30 >2.2% (n = 3). Doses varied across all algorithms: cryoprecipitate (10-30 U), FC (3-6 g), platelet (1-2 U), fresh frozen plasma (1-4 U), and prothrombin complex concentrate (PCC) (5-50 U/kg).

Conclusion: VHA-guided MHP showed marked variation with inconsistent transfusion thresholds. For similar clot kinetics, dosing of blood products and haemostatic agents differed, particularly PCC. Patients with the same coagulopathy may receive different treatment across hospitals. Centralised standardisation could improve PBM consistency.