Whole blood as an alternative for component transfusion?

Abstract

Blood services commonly separate whole blood (WB) into its components of red cells, platelets and plasma. This enables storage of the components under conditions that optimise their quality for as long as possible, and enables transfusion of only the required components to each recipient. However, there are certain situations where separation and storage of components is not possible, and some evidence that components may not be the best therapy for major trauma. Nevertheless, there are significant risks associated with WB transfusion such as transfusion transmitted infections, alloimmunisation to human leucocyte antigens (HLA), post-transfusion purpura (PTP), and transfusion associated graft versus host disease (TA-GvHD). The use of leucodepletion (LD) filters is relatively simple and has significant benefits such as reduced incidence of febrile transfusion reactions, reduced HLA immunisation, reduced risk of TA-GvHD, and reduced occurrence of PTP. The LD process reliably reduces the transmission risk of cytomegalovirus (CMV) and of Human T-cell lymphotropic virus (HTLV). However, the LD process can be sensitive and it is important that the use of particular LD filters is adequately validated in the conditions of their intended use. The refrigerated shelf life of LD WB collected into an adenine-containing anticoagulant is 35 days, to preserve the quality of the red cells, although some studies indicate that red cell quality falls below acceptable levels by day 28. It is well known that some plasma coagulation factors (particularly FVIII) decline rapidly during refrigerated storage and that refrigerated platelets are rapidly cleared from the circulation following transfusion. Nevertheless, there is interest in the storage of WB that has undergone a pathogen inactivation (PI) process, primarily for use in battlefield situations. A comprehensive in vitro study of the primary haemostatic potential of WB treated with the Mirasol PI system suggests sufficient function may be retained during refrigerated storage for up to 21 days. An alternative approach is the use of fresh WB (FWB) that has undergone a PI process and been stored at ambient temperature for up to 24 h. Initial studies suggest acceptable blood quality, killing of parasites and viruses, and mitigation of the risk of bacterial growth during ambient storage. Further, as the PI system works by disrupting the nucleic acid of contaminating pathogens, this also inactivates any residual leucocytes, reducing the risk of TA-GvHD. The transfusion of FWB in the developing world is a relatively common practice, as not all hospital or blood bank facilities can support component production, but there are arguments against the use of component therapy, such as the delay in obtaining components, the cost (to the patient's family) of the treatment, and the wastage of the plasma. It is clear that the use of component therapy may not be the most appropriate practice for all healthcare systems and the ability to use safely WB, whether fresh or stored, may be of significant benefit. The associated risks may be mitigated to some extent by the use of established and novel techniques, such as LD and PI.