Blood products are vital to increased chance of survival for traumatic battlefield injuries, with up to 15% of casualties with severe trauma requiring massive transfusions, and 20-50% mortality rates in this group (Military Transfusion).
A casualty in the Australian Defence Force (ADF) first has access to blood treatment at the Role 2 Hospital, where Pathology first joins the casualty evacuation link. Blood supply is organised through the J07 and managed at the hospitals by pathology scientists (Military Transfusion). Current blood product options include component therapy supplied by Australian Lifeblood or a Walking Blood Bank (WBB) in emergencies by collecting Whole Blood (WB) from a living donor for immediate transfusion.
Component therapy is the only option for blood products across Australia. Red Cross Life Blood Australia is the only organisation that can collect donations and manufacture blood products in Australia, meaning our walking blood bank is not legal inside Australian borders. Life Blood produce a wide array of different blood products, including Packed Red Blood Cells (pRBC), Fresh Frozen Plasma (FFP), Platelets (PLT), and other blood product derivatives (Lifeblood). In the case of a trauma with large amounts of blood loss, pRBC, FFP and PLT are the main components to make the patient hemodynamically stable.
Supply of blood components can be a logistical challenge as each product has different storage requirements and shelf life. pRBC last 42 days from donation, needing to be kept between 4 oC and 8 oC. FFP can be stored for 12 months at below -22 oC. If FFP is defrosted but not used, it then has a five day expiry and must be kept between 4 oC and 8 oC. PLT only last five days from collection with the requirement of 22 oC and 24 oC in constant motion (Lifeblood).
Australian blood supply entirely relies on donations from volunteers unlike other nations, such as the United States, where donations can be paid for. As a result, this leaves our blood supplies in a precarious position and makes each unit even more valuable. A donation of 470ml whole blood can be made every 12 weeks and be separated into three different products: PLT, Plasma, and Red Cells. Plasma, or PLT, can be donated every two weeks. The significant time difference between the shelf life of each component compared to how often it can be donated just emphasises how limited a resource blood products are, and how frequent resupply may be required even without usage.
Blood groups are another factor to consider and add another level of complexity to this finite resource. Blood type is based on the presence of proteins (known as antigens) on the surface of red blood cells. The most important ones are the A, B and O antigens, with O contains zero of these antigens and AB has both antigens present.
Antibodies are a part of our immune system designed to float in our plasma and recognise foreign bodies. From three months of age, humans naturally develop antibodies to complement their ABO blood type. O cells have no antigen therefore the plasma will have both A and B antibodies, whereas AB cells will have no ABO antibodies. When using component therapy, O cells become the universal donor, as there are no antigens on the surface of the cell to trigger a reaction from a recipient’s plasma and antibodies. However, AB plasma is the universal plasma donor as there are no antibodies present to attach to the recipients red cells (Lifeblood).
The ABO group is the most clinically significant, as a transfusion of a non-compatible blood type will cause a transfusion reaction with high risk of mortality. The next most clinically significant is the Rh system, which indicates the Positive (Pos) or Negative (Neg) associated with blood types. This is a separate antigen from a different gene than the ABO.
Unlike ABO, the human body does not naturally develop antibodies to Rh antigens until it has been exposed to them. This means that Rh Positive blood can be given to an Rh Negative patient, but it is likely that after exposure an antibody will develop and the next exposure could cause a transfusion reaction. ABO and Rh are the two most significant blood group systems, with 43 other different systems currently known for red cell antigens with differing levels of significance (Life Blood). Every transfusion is therefore an exposure to a myriad of red cell antigens that could potentially develop an immune response and cause future transfusion reactions.
The ADF currently utilise pRBC, FFP, and a derivative of FFP called Cryoprecipitate (CRYO) (Health Manual). Due to the short shelf life of PLTs, they are not viable to transport and store constantly in a military environment. Within the reach of Australia, the Australian Life Blood supplies blood product stock through the J07 (Health Manual). Urgent blood products are often required for transfusion before appropriate testing can be completed.
To enable casualties to receive compatible blood before laboratory testing is completed, universally compatible components are used. Type O cells are used for pRBC and type AB for FFP. Of the Australian population, 38% are O Pos, 7% are O Neg, only 4% are AB Pos and 1% AB Neg (Lifeblood). This means only 50% of the Australian population have a universal blood type.
However, of these many will be ineligible or unwilling to donate. This highlights the importance of matching blood type or other compatible blood types where possible to reserve the universal components for emergencies. These statistics are concerning should the ADF need to increase its demand, and leads one to question what alternatives the ADF could use should Life Blood not be able to meet its supply needs.
Frozen blood components have been under research for many years. The ADF has a current project working with Life Blood Australia to develop this as a capability (Lifeblood). PRBC, Plasma and PLT are able to be stored at -80 oc and have shelf lives up to 10 years (Defence Innovation). This allows opportunity for severe reduction in wastage and provides the ability to build up stocks unlike before. Unfortunately, the logistics of transporting, storing, freezing, and reconstituting are not as simple as current blood components. While the work on developing frozen blood as a capability continues, other militaries have turned to collecting their own whole blood (Whole Blood Transfusion (CPG ID: 21)).
Whole Blood (WB) is the term used when a bag of blood has not been separated, and is made up of Red cells, Plasma and Platelets. The main downfall of WB is the rapid degradation of plasma and platelets, greatly reducing the efficacy over time. There is also the issue of the plasma and red cells being in the same bag, so the donor and recipient blood type must match exactly to avoid a transfusion reaction.
The official universal donor was discovered in the form of Low Titre O Whole Blood (LTOWB) (Whole Blood Transfusion (CPG ID: 21)). This is O type blood (therefore no antigens) where the donor produces low enough concentrations of antibodies that it should not cause an adverse reaction. As WB contains all components, treating specific conditions results in other parameters also increasing as the patient is receiving some products they may not need. In the case of trauma, where a patient has been actively bleeding and is going to need replacement of all components, WB shines. It is also only one bag to be hung instead of three, and it is stored in the fridge unlike the FFP that requires defrosting, making it a much faster and more efficient way of treating with blood. Therefore, the decision of whether component therapy or WB is better, is entirely up to the expected patient demographic.
With the release of the Defence Strategic Review came the knowledge that the ADF now has reduced strategic warning time (Defence Strategic Review). Blood is a valuable lifesaving resource, which the ADF will have an increased demand for in future conflicts. It can be seen that what is currently in place will not be suitable, nor will there be time for changes to occur if it is not acted upon now. Failure to innovate the ADF blood plan will affect not just the entire military in the way of higher mortality risk, but the wider Australian population by increasing the need of donors and competition for the existing blood demand.