Massive transfusion: an overview of the main characteristics and potential risks associated with substances used for correction of a coagulopathy.

Massive transfusion (MT) is an empiric mode of treatment advocated for uncontrolled bleeding and massive haemorrhage, aiming at optimal resuscitation and aggressive correction of coagulopathy. Conventional guidelines recommend early administration of crystalloids and colloids in conjunction with red cells, where the red cell also plays a critical haemostatic function. Plasma and platelets are only used in patients with microvascular bleeding with PT/APTT values >1.5 times the normal values and if PLT counts are below 50×10(9)/L. Massive transfusion carries a significant mortality rate (40%), which increases with the number of volume expanders and blood components transfused. Controversies still exist over the optimal ratio of blood components with respect to overall clinical outcomes and collateral damage. While inadequate transfusion is believed to be associated with poor outcomes but empirical over transfusion results in unnecessary donor exposure with an increased rate of sepsis, transfusion overload and infusion of variable amounts of some biological response modifiers (BRMs), which have the potential to cause additional harm. Alternative strategies, such as early use of tranexamic acid are helpful. However in trauma settings the use of warm fresh whole blood (WFWB) instead of reconstituted components with a different ratio of stored components might be the most cost effective and safer option to improve the patient's survival rate and minimise collateral damage. This manuscript, after a brief summary of standard medical intervention in massive transfusion focuses on the main characteristics of various substances currently available to overcome massive transfusion coagulopathy. The relative levels of some BRMs in fresh and aged blood components of the same origin are highlighted and some myths and unresolved issues related to massive transfusion practice are discussed. In brief, the coagulopathy in MT is a complex phenomenon, often complicated by chronic activation of coagulation, platelets, complement and vascular endothelial cells, where haemolysis, microvesiculation, exposure of phosphatidyl serine positive cells, altered red cells with reduced adhesive proteins and the presence of some BRM, could play a pivotal role in the coagulopathy and untoward effects. The challenges of improving the safety of massive transfusion remain as numerous and as varied as ever. The answer may reside in appropriate studies on designer whole blood, combined with new innovative tools to diagnosis a coagulopathy and an evidence based mode of therapy to establish the optimal survival benefit of patients, always taking into account the concept of harm reduction and reduction of collateral damage.