After decades of prioritizing crystalloid solutions for the resuscitation of bleeding patients in the late 20th century, damage control resuscitation (DCR) emerged in the 21st century as the preferred management strategy. This shift was driven by the recognition of acute traumatic coagulopathy and the importance of physiological stabilization prior to definitive surgical intervention.^1,2

A core pillar of this approach involved restricting crystalloid use in favor of balanced resuscitation with blood components in a near-physiological ratio of red blood cells, plasma, and platelets.³ Thus, the exploration of whole blood (WB) resuscitation—rather than ratio-based component therapy—was a logical progression, initially proven effective in military settings and later translated into civilian practice.

Whole blood transfusion has a long historical precedent. Although the first human-to-human blood transfusion was reported in the 17th century, it took another 200 years for the discovery of citrate anticoagulation to enable blood storage outside the body—a discovery that paved the way for modern blood banking just in time for World War I and the Spanish Civil War. Later, during World War II, blood component therapy was introduced, which allowed production of freeze-dried plasma and transatlantic transfusion support for Allied forces.

In the years following World War II, infectious disease concerns, advancements in blood fractionation techniques, and financial incentives further accelerated the shift from whole blood to component therapy. It took five decades for the concept of DCR to fully mature and another 10 years for the benefits of whole blood to be proven on the battlefields of Iraq and AfghanistanClick or tap here to enter text., before WB found its way back into civilian trauma and hemorrhage management.⁴

Although it shares the same name, modern-day WB is distinctly different from the product used a century ago. Because WB contains both plasma and red blood cells, clinicians have long been concerned about potential hemolysis of both donor and recipient red cells due to pre-existing blood group antibodies in the donor or recipient. Consequently, early protocols mandated strictly ABO-identical transfusions of WB. This limited the utility of WB in emergency scenarios, where a patient’s blood type is typically unknown during initial resuscitation. Further, traditional leukoreduction filters depleted the unit of platelets, compounding a long-held concern that cold storage compromised platelet functionality.

To address these concerns, platelet-sparing leukoreduction filters were developed, and the clinical efficacy of cold-stored platelets in active hemorrhage was demonstrated. Additionally, modern whole blood is harvested exclusively from group O donors who have been screened for low titers of anti-A and anti-B antibodies. These advancements prompted the Association for the Advancement of Blood & Biotherapies to update its standards, shifting from a strict requirement for ABO-identical WB to permitting the use of low titer group O whole blood (LTOWB) based on recipient ABO compatibility with the red blood cell component.⁵ As a result, LTOWB can now be used as a universal product in austere situations where the recipient’s blood group is unknown.

The perceived benefits of WB resuscitation stem from its composition and logistics. It is believed that compared to component therapy, a unit of whole blood contains a higher concentration of coagulation factors, platelets, and a higher hematocrit, and contains less additional solution. Therefore, higher concentration of hemoglobin and fibrinogen can be delivered in less volume, which is in line with paradigms of DCR. Moreover, component-based resuscitation requires multiple bags to be hung.

Whole blood simplifies the process into a single bag that contains an optimal ratio of products. It relieves the need for plasma to be thawed or for platelets to be agitated. And depending on the anticoagulant and preservative used, it has a shelf life of 21 days when refrigerated at 1-6°C, which is longer than either thawed plasma or platelets. These operational advantages are uniquely critical in prehospital, trauma, and tactical environments. In these settings, WB allows for simplified and expedited delivery while inherently achieving a balanced resuscitation, which would otherwise be near-impossible. Compelled by these benefits, the Joint Trauma System consensus guidelines recommended LTOWB as the resuscitative fluid of choice for hemorrhagic shock in combatClick or tap here to enter text., a practice that has since expanded into civilian trauma systems globally.^4,6

As the practice of LTOWB transfusions in the acute phase of trauma expands globally and establishes itself as a centerpiece for hemorrhagic shock resuscitation, it is important to recognize that despite great strides made in product optimization, delivery protocol implementation, and observational studies showing feasibility and benefit, clinical trials have yet to establish a clear benefit profile on patient-centered outcomes when compared to component therapy. Most notably, the SWiFT (Study of Whole Blood in Frontline Trauma) and TOWAR (Type O Whole Blood and Assessment of Age during Prehospital Resuscitation) trials published in the New England Journal of Medicine in the spring of 2026 both failed to show a mortality benefit.

SWiFT, the first large-scale randomized trial evaluating prehospital whole blood against component therapy in trauma, found that up to two units of prehospital WB was not superior to standard care in preventing 24-hour mortality or reducing massive transfusion requirements, though its distinct logistical advantages remain compelling.⁷ Published shortly thereafter, the TOWAR trial similarly demonstrated no statistically significant difference in 30-day all-cause mortality, though the point estimate numerically favored the component therapy arm (25.9 percent in the whole blood group versus 20.5 percent in the component group).⁸

While proponents of WB point to methodological limitations within these studies to explain the lack of observed clinical effect, these landmark trials nonetheless indicate that while whole blood offers significant operational and logistical utility, it has yet to prove clinical superiority over pragmatic component therapy.

When implementing whole blood protocols, its operational advantages must be balanced against the potential risks of deviating from established component therapy standards. The primary clinical concerns surrounding WB transfusion include hemolytic transfusion reactions, alloimmunization, and inventory management constraints. Ideally, whole blood units are harvested from group O, RhD-negative male donors with low anti-A and anti-B titers.⁹

This strategy reduces the risk of acute hemolysis from pre-existing group-specific antibodies, minimizes risk of alloimmunization, and decreases risk of transfusion-related acute lung injury. But these donors are scarce. Therefore, institutions that have implemented whole blood for all massive hemorrhage protocol activations frequently must rely on group O-positive blood to sustain their inventories. This comes with a potential risk of RhD alloimmunization in RhD-negative recipients—a risk that has been studied in detail, quantified, and many advocates of whole blood believe is negligible compared to the benefits gained. ^10,11

Safety profiles represent another point of concern in the whole blood debate, specifically regarding pathogen reduction. Although individual platelet and plasma units can undergo pathogen inactivation, an approved method from the Food and Drug Administration for whole blood remains elusive. Proponents counter this by noting that universal pathogen reduction has yet to be fully realized across all blood products in the United States (in Canada almost all platelets are pathogen-inactivated, and plans are in place to switch to pathogen-inactivated plasma in the near future). Further, the baseline risk of these infections in the current donor pool is exceedingly low, and WB may theoretically reduce cumulative infectious risk by limiting the number of donor exposures compared to component therapy.

In the coming years, the use of LTOWB for acute hemorrhage resuscitation is expected to expand. The greatest impact is likely to be in prehospital settings with prolonged extrication where logistics matter the most. Increasingly, emergency departments and prehospital services are expected to incorporate this new tool into their everyday protocols. This will be a welcome change because the greatest advantage of whole blood in resuscitation is reducing clinical team workload, possibility of errors, and waste. It will offer a simpler way of achieving the goals of DCR.

However, the shift will impose increased demand on the blood supply and will bear risks avoidable by using component therapy. In settings where component-based resuscitation remains a viable and accessible option, the medical community must carefully weigh the core tenet of “first, do no harm” before mandating a definitive shift in standard practice.

Dr. Tabatabaey is an emergency medicine specialist at Oakville Trafalgar Memorial Hospital and a Transfusion Medicine Fellow at Canadian Blood Services and the University of Toronto. He has also completed a master’s degree in health informatics at the University of Toronto Institute of Health Policy, Management, and Evaluation.  His interests include management of bleeding in the emergency department, management of bleeding during mass casualty incidents, goal-directed bleeding management, and health informatic solutions in transfusion medicine.

References

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