Page 103 - JSOM Fall 2025

Advocating for the Prehospital Administration
of Low-Titer O+ Whole Blood

Dispelling Myths and Misinformation

Stephen P. Wood, DMSc, ACNP-BC, NRP

ABSTRACT
The prehospital administration of low-titer O whole blood against prehospital LTOWB are often presented with the ca-
(LTOWB) has gained attention as a lifesaving intervention veat that we need more scientific evidence before universal
in trauma care, demonstrating associated significant survival support of this practice. This article will explore the science
benefits over traditional crystalloid and component therapies. behind these arguments, including concrete data on risks and
Despite a growing body of evidence from both military and benefits of this therapeutic modality.
civilian studies supporting its efficacy, safety, and feasibility,
LTOWB continues to face criticism. This article examines The Delivery of LTOWB Requires
commonly raised objections, including concerns over patient Rewarming to be Effective
identification, blood rewarming, transfusion reactions, and
potential risks for childbearing women. Emphasizing the need It is likely optimal to transfuse blood, or any fluid, close to or
for transparency and evidence-based progress, this article ad- at physiological temperatures. This process can be achieved
vocates for the integration of LTOWB into prehospital pro- through administration via a blood or fluid warmer. One of
tocols, positioning it as a crucial advancement in emergency the arguments against delivering prehospital whole blood is
medical services and trauma care. that it is challenging to deliver warm blood in this environ-
ment. Agencies wanting to deliver LTOWB have had to pur-
Keywords: whole blood; prehospital transfusion; ethics; chase and train on blood warmers, which has both logistical
transparency and financial implications.

However, a closer inspection of the science and principles of
the thermodynamics of fluid delivery suggests that while hy-
Introduction
pothermia is detrimental in trauma, delivery of 1–2 units of
The use of low-titer group O whole blood (LTOWB) has been cold LTOWB can be mitigated and may be of limited clinical
a controversial topic and has polarized the field of prehospital consequence. To explore this, we need to look at how fluids in-
medicine. Proponents point to the extensive military experience teract with each other in a closed system like the human body.
and the growing civilian experience that LTOWB saves lives
compared to crystalloid or component therapy. While it can be The thermal equilibrium formula or the heat mixing formula is
argued that the military experience does not always translate to a thermodynamic calculation that can be used to estimate the
civilian trauma, there is a growing body of evidence supporting temperature change that occurs when mixing two fluids. The
LTOWB in this environment. Most recently, a systemic review formula is as follows.
1–3
of civilian-administered blood by Morgan et al. demonstrated
4
that LTOWB was associated with improved 24-hour survival Tf = (m1 * c1 * T1) + (m2 * c2 * T2) / (m1 * c1) + (m2 * c2)
(risk ratio [RR] 1.07 [95% CI 1.03–1.12) and late survival (RR
1.05 [95% CI1.01–1.09) compared to component therapy. The Where Tf = final temperature after mixing; m = fluid mass; and
ability to identify appropriate patients, as well as the safety, c = specific heat capacities of the fluids; and T1 and T2 are the
efficacy, and feasibility of the delivery of prehospital LTOWB, initial temperatures of the fluids.
has been demonstrated by several authors as well, supporting
the safety and feasibility of this practice. 5–9 If the two fluids are the same, the formula is even more
simplified:
Despite this growing body of literature that supports the use
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of LTOWB in prehospital trauma resuscitation, as well as the Tf = m1 * T1 + m2 * T2 / m1 + m2
clear harms of crystalloid resuscitation, the prehospital ad-
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ministration of LTOWB is not without its critics. These critics The specific heat capacity of blood is approximately 3.6J/gC.
12
often cite that paramedics are unable to identify the appropri-
ate patients, are unable to rewarm blood, and report safety Thus, if we mix 250mL of whole blood that has been stored
issues including transfusion reactions and alloimmunization, at 6oC into a 5L volume of blood at 35°C, we will get the
as well as the potential for waste. These oft-cited arguments following:
Correspondence to s.wood@northeastern.edu
Stephen P. Wood is affiliated with Northeastern University, Boston, MA.

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