Blood in EMS Part 2

Choosing patients and blood products

Choosing patients and products requires clinical judgment, reliable supply and a partnership between EMS and transfusion medicine. Conceptual illustration.

A prehospital blood program has to answer two questions before the cooler opens: which patients should receive a transfusion, and which products can the system deliver safely? I support expanding access to blood in EMS. That commitment becomes more useful when it is paired with clear patient selection, an honest reading of the evidence and a dependable partnership with transfusion medicine.

Part 1 examined the argument for earlier resuscitation and why proximity to an emergency department should not, by itself, settle the discussion. Part 2 looks at the decisions that follow. Whole blood, red cells and plasma have different characteristics. The patient in front of the crew, the available product and the receiving hospital all matter.

This article addresses program design and the evidence behind those choices. It does not establish transfusion triggers, doses or an EMS treatment protocol. Those decisions belong to local medical oversight and the blood bank.

Select patients using suspected bleeding and perfusion

The 2025 National Association of EMS Physicians position statement recommends using a combination of physiologic findings and injury patterns when establishing indications for prehospital transfusion. That supports an assessment of suspected significant blood loss alongside the patient's circulation and evolving condition, rather than a decision based on mechanism or a single blood-pressure reading alone. [1]

For a local pathway, the practical questions are whether serious bleeding is likely, whether the patient shows evidence of inadequate perfusion, and how the findings change during reassessment. Visible hemorrhage is only part of that assessment. Injury patterns can raise concern for bleeding that crews cannot see. A low blood pressure also requires interpretation because hypotension has causes other than hemorrhage. [1] [2]

My recommendation is to train those decisions through realistic cases that include uncertainty. Crews need to recognize the patient who may benefit and explain the findings supporting treatment. They also need practice identifying alternative causes of shock and asking for clinical support. A product on the ambulance should improve access to indicated care, without becoming a reason to transfuse every unstable patient.

The written pathway should connect eligibility with repeated assessment, hemorrhage control, medical consultation when required and timely movement toward definitive care. [2]

Patient selection combines suspected significant bleeding with perfusion findings and reassessment. No single vital sign tells the whole story. Conceptual illustration. [1] [2]

Understand what each product supplies

Packed red blood cells provide oxygen-carrying red cells. Plasma supplies coagulation factors and does not replace red cells. Platelets contribute to clot formation. Whole blood contains red cells, plasma and platelets together. These basic functions explain why a bag of crystalloid cannot replace everything lost during major hemorrhage. [3]

Low-titer group O whole blood, usually abbreviated LTOWB, brings those components together in one product. A service carrying red cells and plasma uses separate products with separate handling requirements. Red cells alone do not provide the same clotting support as a strategy that also supplies plasma and platelets. [3] [4]

Product availability and preparation also matter. Liquid, thawed and dried plasma are not interchangeable operationally. A blood bank must define which products a service will carry, how they are prepared and how the prehospital inventory connects with hospital resuscitation. [2]

I would assess product choice against patient needs, supply reliability, crew capability and receiving-hospital practice. A dependable component program deserves consideration alongside whole blood. The evidence does not justify treating every service without whole blood as clinically inadequate.

Red cells, plasma and LTOWB supply different components and require an agreed clinical pathway. The 2026 trials did not establish whole-blood superiority over components. [3] [4] [5] [6]

Read the 2026 trials as product comparisons

The SWiFT randomized trial, conducted across ten air ambulance services in England, compared prehospital whole blood with red cells and plasma. Whole blood did not demonstrate superiority for the primary outcome of death or massive transfusion within 24 hours. This was a comparison between transfusion strategies, rather than blood versus no prehospital blood. [5]

The TOWAR randomized trial compared prehospital type O whole blood with component therapy consisting of red cells, plasma or both. It did not demonstrate a reduction in 30-day mortality with whole blood. Failure to show superiority does not prove that the products are equivalent in every circumstance. [6]

For EMS leaders, these findings qualify claims that whole blood must always outperform components. They do not establish that withholding indicated prehospital transfusion is preferable. The 2025 NAEMSP recommendation favoring LTOWB preceded these trials, so current product decisions should consider the guidance and the newer evidence together. [1] [5] [6]

Low titer group O does not mean zero compatibility risk

Group O red cells lack A and B antigens, but the plasma in group O whole blood contains anti-A and anti-B antibodies. Those antibodies can create compatibility concerns for recipients with other ABO groups. Selecting donors with low antibody titers reduces that risk; it does not eliminate it. [4]

The definition of low titer varies between testing methods and blood suppliers. An EMS agency should therefore obtain the actual specification for its supplied product and use the recipient policy agreed with its blood bank. The phrase universal blood is too imprecise to substitute for that work. [4]

RhD decisions need a follow up plan

RhD is a separate compatibility issue. Exposure to RhD-positive red cells can lead an RhD-negative recipient to develop anti-D antibodies, with implications for future transfusions and pregnancies. The decision about emergency product access must also account for the immediate danger of life-threatening hemorrhage. [7]

A 2026 joint position statement advises that clinically indicated RhD-positive products should not be withheld when RhD-negative products are unavailable. It calls for institutional pathways covering antibody surveillance, counseling and specialist follow-up, with selective Rh immunoglobulin prophylaxis for low-volume exposures. EMS handoff must preserve the product and exposure information needed for that follow-up. [7]

ABO and RhD pose different compatibility questions. Emergency access, documentation and follow-up should be planned with transfusion specialists. [4] [7]

Children need a pediatric pathway

Children deserve explicit inclusion in program planning. A 2023 JAMA Pediatrics registry study found an association between prehospital transfusion and lower mortality among injured children compared with beginning transfusion in the emergency department. The study was observational, so it cannot establish that transfusion timing alone caused the difference. [8]

The pediatric pathway must address recognition of shock, weight-based administration and the equipment and skills needed to deliver blood to a child. An adult unit should not become an automatic pediatric dose. Training and medical oversight need to make those differences usable during an uncommon, stressful encounter. [8]

My recommendation is to resolve pediatric eligibility before deployment and test it in simulation. A service should know which children it can treat, when additional support is required and how it will communicate with the appropriate receiving team.

Include medical bleeding without overstating the evidence

Severe gastrointestinal or obstetric bleeding can also produce hemorrhagic shock. The 2025 Prehospital Blood Transfusion Coalition guideline addresses hemorrhagic shock regardless of etiology. That supports considering these patients during pathway development, rather than limiting every discussion to an injured adult. [2]

The evidence reviewed here does not establish an identcal survival benefit for every bleeding condition. Adult trauma trials cannot settle product choice or selection criteria for all medical and obstetric patients. Local planning should involve the relevant hospital specialists and define when transfusion, specialist consultation and destination coordination are appropriate.

International programs offer different models

There is no single worldwide prehospital blood model. The following examples describe specific publications and programs at stated dates. They should not be read as current protocols for every ambulance in a country or as proof that one inventory produces better survival.

In the United States, the 2025 NAEMSP statement recommends blood products over crystalloids for traumatic life-threatening hemorrhage where a high-quality prehospital transfusion program can be supported. It favors LTOWB while emphasizing clinical oversight and blood-bank partnerships. This is professional guidance, not a nationwide requirement that every ambulance carry blood. [1]

In England, SWiFT demonstrates that a network of air ambulance services could deliver and compare whole blood with red cells and plasma in a randomized trial. The study provides evidence about that comparison. Its design and findings do not describe the inventory of every British ground ambulance. [5]

A 2021 Norwegian survey described air ambulance and search-and-rescue services carrying different combinations of dried plasma, red cells and LTOWB. It documented how programs worked with blood banks and reported their experience. It did not compare patient survival between products, and its inventory snapshot should not be presented as a 2026 national census. [9]

A survey published in 2024 examined prehospital and retrieval services across Australia and Aotearoa New Zealand. It found variation in blood carriage and product selection. That is useful evidence of different delivery models across services, rather than a single national whole-blood policy or a trial establishing which inventory is best. [10]

Canadian Blood Services' 2025 information on leukocyte-reduced whole blood describes civilian hospital access for clinical trials beginning in January 2025. That is a specific supply and research arrangement. It should not be converted into a claim that Canadian ambulances generally carry whole blood. [4]

My practical lesson from these examples is to compare capabilities as well as products. Who can bring blood to the patient? Which patients are eligible? How does that care connect with the hospital? A helicopter team, a specialist response vehicle and a frontline ambulance service may need different deployment arrangements.

Selected, dated examples illustrate variation in products and delivery models. Program surveys and supply arrangements do not establish a survival advantage. [1] [4] [5] [9] [10]

Adapt military lessons to civilian responsibilities

The Joint Trauma System's prehospital transfusion guideline, published in 2020 and rapidly updated in June 2023, emphasizes medical direction, deliberate training and logistical support. It also addresses military blood-supply arrangements that are specific to deployed care. Those arrangements should not be copied into civilian practice without the required transfusion-service controls and legal authority. [11]

The useful planning question is what a civilian service must have in place to deliver its chosen product reliably. Military experience can inform that discussion, while civilian patient populations, regulatory requirements and hospital partnerships still require their own decisions.

Make the hospital handoff part of product selection

Prehospital transfusion begins a treatment course that continues after arrival. Product identity, unit traceability, timing, clinical response and any suspected reaction need to accompany the patient. The receiving team also needs the information required for continued resuscitation and compatibility follow-up. [2] [7]

My recommendation is to design that handoff before choosing the final inventory. A joint simulation can expose missing information, unclear responsibilities or incompatible documentation. The blood bank and receiving clinicians should help define the handoff that crews will actually use.

Resolve the clinical decisions before deployment

For a service considering blood, I would begin with a focused meeting involving EMS medical leadership, field clinicians, the blood bank and receiving-hospital partners. The aim should be a written set of decisions that everyone can explain.

Define the eligible bleeding presentations and the assessment supporting transfusion. Identify the actual products available, their compatibility specifications and the plan when the preferred product is unavailable. Resolve pediatric and reproductive considerations, consultation requirements, documentation and responsibility for follow-up.

Those are my proposed planning priorities, not a validated score or a universal protocol. Their value is practical: they expose unresolved clinical questions while there is still time to answer them together.

EMS, the medical director, the blood bank and receiving clinicians should resolve eligibility, product policy and handoff responsibilities together.

Discuss your next step with Astera

At Astera Global Solutions, we help EMS and healthcare organizations connect education, clinical quality and system design. If your organization is exploring prehospital blood, bring your patient-selection and product questions to the medical director and blood bank, then identify where planning or education support would help.

Visit Astera Global Solutions or email info@asteraglobalsolutions.net to discuss your organization's needs. Which decision is most difficult in your system: selecting patients, securing the right products or coordinating care after transfusion?

Coming in Part 3

Part 3 will examine implementation: supply partnerships, cold-chain protection, warming, competency, inventory rotation, cost, waste and continuous quality improvement. The goal is to turn the clinical decisions discussed here into a program that crews and hospital partners can sustain.

References

1. Brown, J. B., Yazer, M. H., Kelly, J., et al. (2025). Prehospital Trauma Compendium: Transfusion of Blood Products in Trauma. NAEMSP position statement and resource document. Prehospital Emergency Care. Read source

2. Levy, M. J., Schaefer, R. M., Obyrne, H., Krohmer, J. R., Bank, E. A., & Holcomb, J. B. (2025). Prehospital Blood Transfusion Coalition clinical practice guideline for civilian emergency medical services. Trauma Surgery & Acute Care Open, 10(3), e001931. Read source

3. American Red Cross. (n.d.). Blood components. Accessed October 19, 2026. Read source

4. Canadian Blood Services. (2025). FAQ: Whole blood, leukocytes reduced (LrWB) at Canadian Blood Services. Accessed October 19, 2026. Read source

5. Smith, J. E., Cardigan, R., Sanderson, E., et al. (2026). Prehospital whole blood in traumatic hemorrhage: A randomized controlled trial. New England Journal of Medicine, 394, 2305-2316. doi:10.1056/NEJMoa2516043. Read source

6. Sperry, J. L., Guyette, F. X., Cotton, B. A., et al. (2026). Prehospital resuscitation with type O whole blood for trauma and hemorrhage. New England Journal of Medicine, 394, 2317-2328. doi:10.1056/NEJMoa2602167. Read source

7. Henry, R., Coleman, J. R., Holcomb, J. B., et al. (2026). Post-transfusion management of RhD-negative females of childbearing potential following RhD-positive transfusion. Joint position statement and resource document; title abbreviated. Journal of the American College of Surgeons. Published online July 22, 2026. doi:10.1097/XCS.0000000000002099. Read source

8. Morgan, K. M., Abou-Khalil, E., Strotmeyer, S., Richardson, W. M., Gaines, B. A., & Leeper, C. M. (2023). Association of prehospital transfusion with mortality in pediatric trauma. JAMA Pediatrics, 177(7). Read source

9. Bjerkvig, C. K., Strandenes, G., Hervig, T., Sunde, G. A., & Apelseth, T. O. (2021). Prehospital whole blood transfusion programs in Norway. Transfusion Medicine and Hemotherapy, 48(6), 324-331. Read source

10. Wigginton, O., Johnson, S., Jervis, B., Joshi, A., Steere, M., & Ferguson, I. (2024). Prehospital blood transfusion: A cross-sectional study of prehospital and retrieval medicine services across Australia & Aotearoa-New Zealand. Prehospital Emergency Care. Read source

11. Joint Trauma System. (2020; rapid update June 2023). Prehospital blood transfusion. Clinical Practice Guideline ID 82. Publication date October 30, 2020. Read source