Massive haemorrhage and transfusions each change coagulation plasma factor function

Blood transfusion is a crucial component of managing acute haemorrhagic shock. However, uncertainty remains about which blood product, or combination of products, is most effi cacious for adequate tissue oxygenation and haemostasis. Platelet dysfunction has been identifi ed as one of the main causes of post-operative bleeding, although no correlation exists between peri-operative platelet aggregation and the magnitude of post-operative blood loss. Our aim was to investigate the contribution of platelet and plasmatic components to overall haemostasis following acute massive haemorrhage and transfusion of packed red blood cells (PRBC) in an ovine model. Nine sheep were anaesthetised, bled 30% of their blood volume, then transfused with PRBC 30 min later and monitored for four hours. Blood samples were collected following anaesthetic induction (baseline), post-haemorrhage and every hour post-transfusion. Samples were analysed using the rotational thromboelastometry device, ROTEM®. The contribution of the extrinsic coagulation factors and platelets to clot formation was assessed by ex-tem®, the contribution of fi brinogen and fi brin polymerisation to clot formation by fi b-tem®. Maximum clot fi rmness, which represents overall clot strength and stability, was signifi cantly decreased post-transfusion from baseline values in both ex-tem® (p less than 0.001) and fi b-tem® (p less than 0.001), and decreased more signifi cantly from post-haemorrhage values in fi b-tem® (p less than 0.001) compared to ex-tem® (p less than 0.01). Platelet counts did not change signifi cantly throughout the experiment. These results suggest that the observed changes in haemostasis in this model of acute massive haemorrhage could be due to plasmatic factors, specifi cally functional fi brinogen and/or factor XIII, rather than platelet number or function. Further investigation into such plasmatic factors is required to clarify this