From whole blood to blood components…and back again!
Thursday, December 05, 2019 Dr. Geraldine Walsh
What’s old is new again. Recent research has shown that whole blood may be the best fluid to replace what’s being lost in actively bleeding patients. However, for the past 50 or so years, whole blood for transfusion has not been readily available in Canada or many other countries. To support the (re)-introduction of this product to the Canadian Blood Services formulary, the Centre for Innovation’s product and process development group, under the leadership of Ken McTaggart, has been working to understand this product and the optimal processes to produce and store it. How did we get here? A quick recap of the history of blood transfusion will help explain.
Necessity is the mother of invention
The history of blood transfusion is intimately linked with efforts to save the lives of soldiers, particularly during the First World War. The types of injuries sustained by soldiers on the front lines of conflict can be horrific and quickly lead to “traumatic hemorrhagic shock” – massive and potentially fatal blood loss. Fluid resuscitation – replacing the lost fluid – is necessary to save patients with shock. During the First World War, fluid resuscitation was often done using saline solution or other colloid solutions.
The introduction of citrated whole blood was an important early innovation in blood banking that took place during the First World War. Citrate is an anticoagulant – it prevents blood from clotting. Adding it to whole blood allowed the donor and the patient to be separated in time and space for the first time. Canadian physician L. Bruce Robertson was a pioneer of this approach. He drew blood from donors, added citrate and stored the blood in one-litre glass bottles. The blood could be stored for several days, and the bottles packed in boxes with sawdust and ice and sent to the front lines for transfusion to casualties.
For the next 50 years after the First World War, citrated whole blood was the standard transfusion product provided for patients in military and civilian settings.
The era of blood component therapy
In the 1960s, another innovation heralded a dramatic change in blood banking and blood transfusion. The advent of polyvinyl chloride (PVC) “plastic” containers and closed sterile sets of tubing ushered in the era of blood component therapy. This led to a big shift in the way blood was processed and transfused to patients. Blood could now be separated into its components – red blood cells, plasma and platelets. This brought many advantages. The components can be stored separately using the optimal storage conditions and shelf lives for each component. A single blood donation can be made into several products and can help more patients. Patients can be given just the component they needed, which reduces the risk of adverse reactions.
Component therapy has remained the standard of care in almost all clinical situations for the past 50 years, including trauma. Blood components, as well as crystalloids and colloids, became standard therapy for patients with active bleeding. There were, however, some drawbacks with early approaches following the shift away from whole blood transfusion. This led to a shift in recent years to a new standard-of-care approach: balanced transfusion of components for patients who are actively bleeding. In many trauma centres, these “massive transfusion protocols” give plasma, platelets, and red blood cells in a balanced 1:1:1 or 1:1:2 ratio.
Recognizing the limits
Even more recently, there’s been growing recognition that adherence to these massive transfusion protocols can be difficult or impossible. For the military, the different storage requirements for each component and other logistical challenges make it difficult to provide the components where they are needed. In rural or remote civilian trauma centres, platelets are rarely available, and plasma, if available, needs to be thawed which takes time. Even in large urban centres, the necessity of multiple components, which means multiple fridges/freezers, multiple bags, and overall a highly complex protocol, can lead to challenges. These constraints are especially important when you consider that for patients suffering from traumatic hemorrhagic shock, time is critical. The window to save these patients’ lives is counted in minutes, not hours.
What’s old is new again
Recent research has shown that the optimal fluid to replace what’s being lost by actively bleeding patients is likely whole blood. Transfusing whole blood increases the fluid volume, while treating the loss of oxygen and helping to promote blood clotting. It simplifies the resuscitation efforts, particularly in austere, pre-hospital or military environments. Clinical evidence has shown that whole blood is no worse than, and is perhaps better than, current trauma protocols. Even more promising, if the whole blood is stored cold before transfusion, it appears to have an equal or better effect on bleeding than component therapy, which uses platelets stored at room temperature.
Why the need for research?
Despite it not being a new approach, there are many questions that need to be answered to successfully re-introduce whole blood to the formulary. Since whole blood was last used, it has become standard practice to leukoreduce components. This is a process that removes white blood cells from blood components and increases their safety by reducing the risk of adverse reactions. Questions remain about how best to incorporate leukoreduction into the whole blood production process. There are also questions about how long whole blood can be stored.
Another critical question is which whole blood product should be produced. Component therapy allows for “universal” components to be made available – components that can be transfused to anyone (i.e.: AB plasma or O red blood cells). There is, however, is no “universal” whole blood. This could be a drawback, especially because whole blood will be used in trauma situations where time is critical and the patient’s blood type might not be known. There are, however, blood types that are more suitable for transfusion to many, and these need to be investigated and better understood.
Want to learn more?
Look out for our next “D is for Development” post (coming early 2020) to learn more about the Centre for Innovation’s research work to support the reintroduction of whole blood for transfusion.
Previous posts in the D is for Development series:
From the AABB: Key dates in blood transfusion history
Canadian Blood Services – Driving world-class innovation
Through discovery, development and applied research, Canadian Blood Services drives world-class innovation in blood transfusion, cellular therapy and transplantation—bringing clarity and insight to an increasingly complex healthcare future. Our dedicated research team and extended network of partners engage in exploratory and applied research to create new knowledge, inform and enhance best practices, contribute to the development of new services and technologies, and build capacity through training and collaboration. Find out more about our research impact.
The opinions reflected in this post are those of the author and do not necessarily reflect the opinions of Canadian Blood Services nor do they reflect the views of Health Canada or any other funding agency.
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