Achieving haemostasis in thrombocytopenia in remote settings: an in vitro comparison of frozen and lyophilized products

Abstract

Background - Platelet concentrates have a limited shelf life due to room temperature storage and therefore, are not kept in regional centres where turnover is low. Cryopreserved platelets have been proposed as an alternative to platelet transfusion in austere circumstances and fibrinogen concentrate has improved thromboelastometry parameters in thrombocytopenia. This study compared the ability of stored haemostatic products and platelets to correct thromboelastometry parameters in thrombocytopenia. Materials and methods - Blood from eight patients with severe thrombocytopenia was combined with platelet concentrates, cryoprecipitate, fibrinogen concentrate, factor VIII, factor XIII and cryopreserved platelets in ratios equivalent to transfusion. Tissue factor initiated thromboelastometry (EXTEM) was compared between the products. Results - EXTEM amplitude at 20 minutes (A20) improved by 13.1 mm with platelets (p<0.01). The 5mm increase in A20 seen with cryoprecipitate (p=0.06) was not statistically different from platelets (p=0.19). No improvement in A20 was observed with cryopreserved platelets or factor concentrates. EXTEM clotting times (CT) improved with cryopreserved platelets (19.4 s, p=0.001) and cryoprecipitate (24.1 s, p<0.05), but not fibrinogen, and both were superior to platelets (9.9 s, p<0.05). Clotting concentrates did not improve EXTEM parameters although further studies suggested the improvement in A20 was largely driven by higher fibrinogen concentrations in cryoprecipitate. Discussion - These results suggest that cryopreserved platelets enhance clot initiation but do not contribute to clot strength in thrombocytopenia. When platelets are not available for transfusion, cryoprecipitate may be of value, however this requires further clinical studies.