From battlefield to community: Simulation‐based education for walking blood bank whole blood transfusion

Abstract

Background

Field transfusion of whole blood is vital for patients in hemorrhagic shock, particularly in austere or resource‐limited environments. Military use of warm fresh whole blood (WFWB) has inspired civilian interest in walking blood banks (WBBs) for rural, prehospital, and mass casualty settings where blood product access is limited. However, standardized training and proficiency benchmarks are lacking. This project developed a checklist and established validity evidence to assess provider proficiency in WFWB collection and transfusion.

Study Design and Methods

A multidisciplinary panel created a checklist and modified an existing training video for WFWB collection and transfusion. Using simulation, medical students, nurses, nurse practitioners, physicians, and emergency medical service providers were evaluated to validate the checklist and define proficiency thresholds. Participants (n = 41) were categorized as novice (n = 12), intermediate (n = 13), or expert (n = 16) based on experience. After reviewing the video, participants performed simulated procedures graded by independent evaluators. The maximum score was 47 points, with competency defined by expert performance.

Results

Analyses of variance revealed significant differences between novice and intermediate (p <.01) and novice and expert (p<.01) groups, but not between intermediate and expert (p = .09). Mean rubric scores and completion times were: novice (31/47; 41 min 17 s), intermediate (38/47; 33 min 7 s), expert (41/47; 29 min 19 s). The competency threshold was set at 41/47 and 33 min 27 s.

Discussion

The validated checklist and training video provide a foundation for standardized WFWB education and proficiency assessment, supporting safe WBB implementation in military and civilian settings.

Abbreviations

ANOVA

analyses of variance

cGMP

current good manufacturing practice

CSWB

cold stored whole blood

EMS

emergency medical service

EMT

emergency medical technician

FDA

food and drug administration

IV

intravenous

NP

nurse practitioner

RN

registered nurse

SD3

skills decay, delay and determination

WB

whole blood

WBB

walking blood bank

WFWB

warm fresh whole blood

1. INTRODUCTION

Hemorrhagic shock is the number one cause of preventable death in trauma and is also a significant cause of mortality in other patient populations. ¹ In conjunction with prevention and hemorrhage control, hemostatic resuscitation is an effective mechanism in preventing mortality from hemorrhagic shock. ² Furthermore, whole blood (WB) is once again becoming the preferred product for resuscitation of the hemorrhaging patient. ² A patient who is resuscitated with WB is going to receive either warm fresh whole blood (WFWB) or cold stored whole blood (CSWB). WFWB refers to WB that is collected and remains viable at room temperature for up to 24 h after collection, usually from a “walking blood bank” (WBB). WFWB can either be stored at room temperature and used within 24 h of collection (and then destroyed if not used) or it can be refrigerated within 8 h of collection, after which point it becomes CSWB. ³ WBBs utilize WFWB from immediately available donors, often in low‐resource or austere environments where CSWB is not available or in short supply. ⁴

Military medicine has shown the value of WBBs for over a century. ⁵ WBBs were used on the battlefield of World War I to resuscitate wounded soldiers. ⁵ They were also used in prisoner‐of‐war camps in Southeast Asia in World War II, where they had a little more than a handmade bamboo needle and sterilized jars for collection. ⁵ , ⁶ Even in modern conflicts such as Iraq and Afghanistan, WBBs were utilized during mass casualty incidents, massive transfusion protocol activations, and far‐forward austere environments. ⁷ During these times, WBBs were activated when CSWB was unavailable or to preserve CSWB stock for impending future engagements. Through the crucible of combat casualty care, military medicine has shown us that WBBs can be safe, feasible, and lifesaving during critical moments.

In recent years, interest in civilian WBBs has grown in response to emergency preparedness programs for natural disasters and mass casualty incidents. However, only a few programs worldwide have implemented or at least developed functional systems. In the United States, the Southwest Texas Regional Advisory Council, through its Heroes in Arms program, plans to use prescreened donors who can be rapidly activated to donate WB during mass casualty events or blood shortages. ⁸ Similarly, the Colorado Whole Blood Coalition has created a detailed plan to deploy WBBs for trauma care in remote or mountainous regions where terrain and distance can delay access to trauma centers. ⁹ Internationally, the Norwegian Blood Preparedness Program operates one of the most advanced civilian WBB systems, maintaining four regional networks that have already been used in over nine cases to treat patients in hemorrhagic shock when stored blood was unavailable. ¹⁰

Despite these advances, several barriers continue to limit the broader implementation of WBBs. Major challenges include the lack of FDA approval for the use of WFWB, logistical hurdles, the absence of a prescreened and typed donor pool in the civilian sector, and limited training among medical professionals to safely collect and transfuse WFWB. ⁸ , ¹¹

To address this training gap, as part of the Skills Decay, Delay and Determination Study (SD3), an initiative of the Combat Medical Skills Sustainment Consortium, we developed a simulation model and skills checklist that were used to establish competency thresholds for the collection and transfusion of WFWB. This work aims to enhance readiness and capability for both civilian and military applications of WBBs.

2. MATERIALS AND METHODS

2.1. Study approval and participants

This study protocol was reviewed and approved by the institutional review board at UT Health San Antonio. Secondary approval was provided by the Office of Human Research Oversight. Participants were enrolled with appropriate paperwork and documentation. Participants were identified by recruitment of medical personnel from a variety of medical backgrounds, including medical students, registered nurses (RNs), nurse practitioners (NPs), physicians, and emergency medical service (EMS) providers.

2.2. Study design

2.2.1. Stage 1: Literature review and expert panel review

A literature review was performed to determine the key aspects of a successful WFWB collection and transfusion. Using PubMed and Google Scholar without a date range, terms such as “warm fresh whole blood,” “walking blood bank,” “whole blood collection and transfusion,” “hemorrhagic shock,” “military transfusions,” and “proficiency‐based training” were searched for this literature review. A checklist of the integral steps of the procedure was created and iteratively revised based on current literature, which is available as Supplement 1. The checklist separated the procedure into three sequential sections: (1) a knowledge portion, (2) a collection portion, and (3) a transfusion portion. The checklist was presented to an expert panel and subsequently revised based on panel feedback. Military and civilian experts were selected based on extensive experience and knowledge of WFWB collection and transfusion. This group included physicians, nurses, and pre‐hospital providers from the University of Texas Health San Antonio, University Health, San Antonio Fire Department, United States Army Institute of Surgical Research, and Brooke Army Medical Center. Following this process, a training modality in the form of an educational video was created based on the checklist to be shown to participants before the procedure.

2.2.2. Stage 2: Determining proficiency in simulated training environment

An independent‐measures study design was used to establish comparative scoring between our three levels of expertise. Inclusion criteria were any individuals in training as a medical student, emergency medical technician (EMT), nursing student, or surgical resident, and licensed providers including RNs and EMTs. Exclusion criteria were any individuals not in training or licensed as previously stated in the inclusion criteria. The participants' level of expertise was determined at the time of enrollment based on their years in practice, type of medical practice, and number of prior procedures performed or observed (Table 1). The skill level of participants was the only independent variable, while the task completion time and rubric score were the dependent variables. Before the start of enrollment, graders were trained on the checklist and educational video by an experienced instructor to reduce interrater variability. Participants were enrolled from November 2023 to March 2025.

TABLE 1.

Participant stratification criteria by experience level.

Novice	Intermediate	Expert
Medical students OR 2 0 previous WB transfusions or blood transfusions seen/completed	0<×<2 years as an RN/EMS Provider/NP or a Surgical Resident a AND 2 1–6 previous WB transfusions or 1–20 blood transfusions seen/completed	≥2 years as an RN/EMS Provider/NP AND 2 >6 previous WB transfusions or >20 blood transfusions seen/completed

^a Surgical residents do not need transfusion experience.

Once enrolled, participants watched the educational video that had been adopted from a previous training video created by the Army's Institute of Surgical Research which is available for viewing at the following link: https://www.youtube.com/watch?v=oSC-ri0Ya50. Upon completion of the video, participants were then asked a set of questions related to indications and contraindications for a blood transfusion as discussed within the educational video (Supplement 1, Section A). Following the questions, participants were taken to the procedure room and asked to perform the simulated WFWB collection and transfusion on a manikin model. Supplies available to participants included a blood bag, 18‐gauge needle, intravenous (IV) transfusion tubing, IV insertion kit, scale, 10″ paracord, pressure bag, 4 × 4 gauze, blank blood bag labels, blank Eldon Card, an instruction sheet on how to read an Eldon Card, saline flushes, and standard IV tubing (red herring). Participants utilized either the scale to weigh the bag to 500 g or the 10″ of paracord to approximate the weight. The paracord should wrap around the blood collection bag circumferentially and touch tip to tip if filled appropriately. The grader held onto a completed Eldon card (Figure 1) as well as a pre‐filled 500 cc blood collection bag. The manikin model consisted of two transfusable extremities. The left arm was set up for completion of the donation portion of the procedure (Supplement 1, Section B; Figure 2) while the right arm was set up for the transfusion portion (Supplement 1, Section C; Figure 3).

FIGURE 1.

Completed Eldon card held by the grader.

FIGURE 2.

Diagram of collection arm with labels.

FIGURE 3.

Diagram of transfusion arm with labels.

We first observed, timed, and graded participants as they performed the blood collection on the simulation model according to the checklist. Following the blood collection, the bag of donated blood was weighed for accuracy of transfusion. If the bag weight was ±10% of the target goal of 500 cc, the bag was allowed to be used for the following transfusion procedure. However, if the participant's blood bag weight differed by more than 10% from 500 cc, then the participant's bag was switched out with the pre‐filled 500 cc blood bag to ensure more reliable transfusion times in the transfusion portion of the simulation.

Upon completion of the blood collection, the participant took their blood bag and moved to the right arm of the model, which was set up to receive the transfusion. We then observed, timed, and assessed the participant using the checklist as they completed the transfusion procedures.

The maximum score that an individual could earn for all involved tasks was set to 47 points (4 points for Section A, 17 for Section B, 26 for Section C).

2.3. Statistical analysis

Performance scores represent the sum of correctly answered rubric elements, ranging 0 to 47. Performance times on rubric Sections B and C were reported in total seconds. These data were analyzed with parametric statistics using IBM SPSS Statistics version 27 (IBM Corp., Armonk, NY). Analyses of variance (ANOVA) were used to compare scores and times stratified by experience level. Competency thresholds were established by following the guidelines outlined by Gallagher et al. ¹² Specifically, the mean rubric score and completion time of experts were defined as the competency thresholds for this procedure.

3. RESULTS

We assessed the performance of a WFWB collection and transfusion in a total of 41 participants (12 novices, 13 intermediates, and 16 experts). Breakdown by occupation and expertise grouping is shown in Figure 4.

FIGURE 4.

Number of participants per experience level and specialty.

ANOVA revealed significant differences among experience levels in terms of rubric score (p<.001) and completion time (p <.001). Pairwise comparisons showed that novices had significantly lower rubric scores compared to intermediate‐level medical professionals (31.3 ± 6.2 vs. 37.8 ± 5.8, p = .002) and experts (40.9 ± 2.5, p <.001, Figure 5). Novices were significantly slower than intermediate‐level medical professionals (41 min 17 s ± 8 min 38 s vs. 33 min 8 s ± 7 min 5 s, p = .004) and experts (29 min 19 s ± 4 min 8 s, p <001, Figure 6). On average, participants took the longest time with the transfusion portion (novices 27 min 5 s, intermediates 21 min 20 s, experts 19 min 13 s) compared to the collection portion of the simulation (novices 11 min 27 s, intermediates 11 min 47 s, experts 10 min 6 s). There was a greater difference in mean times between novice and experts in the transfusion portion of the checklist rather than the collection portion (8 min 9 s vs. 1 min 21 s).

FIGURE 5.

Rubric score mean values by experience level with competency threshold at expert mean.

FIGURE 6.

Task completion time mean values in seconds by experience level with competency threshold at one standard deviation above the expert mean completion time value.

Based on these data, the competency threshold for the rubric score was determined to be 41/47 (87.2%) elements correctly completed. Competency threshold was set at 33 min 27 s (i.e., 1 standard deviation above the mean completion time for experts), reflecting our focus on accuracy over completion time.

4. DISCUSSION

We developed a comprehensive and validated checklist, simulation model, and training modality to provide a foundation for educating individuals in the safe collection and transfusion of WFWB. A previous initiative completed by Schauer et al. also created a training video and checklist, showing a time difference in inexperienced versus experienced combat medics. ¹³ Our current work fills a critical gap in standardizing rapid and low‐cost training in both military and civilian WBB programs aimed at improving outcomes in hemorrhagic shock when CSWB is not readily available.

We successfully differentiated novices from intermediate/expert participants, but no difference was seen between the intermediate and expert groups. This lack of differentiation may be attributed to the limited sample size of enrolled participants. With an increase in sample size, we may be able to distinguish between these groups, as our data suggest that experts generally performed at a higher level and completed the procedure more quickly than intermediates. Another explanation could be that there are only two distinct groups: competent versus not competent.

Although we enrolled individuals who were either active or prior military, none had served as combat medics. This group of trained medical professionals warrants further evaluation in subsequent studies, as prior combat experience with real‐world WFWB collection and transfusion may provide advantages. We also did not assess senior surgical residents (Post‐Graduate Year 3–5). There is potential that senior surgical residents could align with expert scores and times due to their years of experience within a surgical specialty.

There are certain key or critical steps within the procedure that are determined as essential to the safety and success of WFWB collection and transfusion. ¹⁴ Critical elements are those that prevent the most dangerous complication of WFWB transfusion, an acute hemolytic transfusion reaction from ABO incompatability. ¹⁴ Therefore, the first critical step was that the participant verbally stated they would perform an Eldon Card on the donor and correctly interpret the grader's completed Eldon Card as O+. For the transfusion portion, we believe the essential steps involve the participant performing a time‐out to confirm the correct recipient, donor, and blood type before starting the transfusion, as well as monitoring for possible transfusion reactions and verbalizing potential clinical signs to be aware of when monitoring for a transfusion reaction.

Time to procedure completion is often used as a competency metric. However, its use alone does not provide a comprehensive picture of competency. Participants may perform a task expeditiously despite critical procedural errors. Alternatively, participants may complete the simulation at a slower speed due to a lack of urgency. When taken into consideration with rubric scoring systems, time can serve as an additional informative competency measure. Simulations lack the consequences that are associated with real‐world scenarios. A hemorrhaging patient can bleed to death in less than 5 min in the absence of timely medical intervention. ¹⁵ Therefore, adding procedural completion time to the evaluation enhances the simulation's “real‐world” applicability.

There are several limitations within this study. First, to increase the utility of this study, a baseline assessment of knowledge and skill prior to any intervention could have been performed beyond our baseline questionnaire (Supplement 1) to obtain more objective data for skill acquisition. Furthermore, the procedures were not conducted under duress conditions reflective of real‐world hemorrhagic resuscitation environments, which may limit external validity.

In this simulation model, a transfusible extremity model was used for the collection and transfusion aspects of WBB performance. Our expert completion times using this model specifically for the collection time were significantly shorter than previously observed collection time performances with some in vivo simulations (10 min 6 s vs. 34.4 min). ¹⁶ This difference could be observed secondary to difficulty in establishment of IV, variation in procedures included within the collection time, and environmental factors that differ between studies. However, when considering the decreased difficulty in IV establishment when using a transfusible extremity model and compared to blood flowing to full blood bag collection in a previous study using in vivo models, our times were almost identical (10 min 6 s vs. 10.7 min). ¹⁷ Furthermore, establishing IV access in an actively hemorrhaging patient is often difficult and may ultimately necessitate intraosseous access for successful resuscitation, which was not evaluated in this model. Additionally, the manikin model was that of white skin tone. We did not simulate using other skin tones due to cost limitations, which may limit the generalizability, particularly when discussing IV placement and recognition of clinical signs of transfusion reaction. Despite these constraints, the model offers a low‐cost, scalable, and broadly adaptable modality for the rapid training of both military and civilian personnel when developing a WBB system. Future phases will prioritize live or field‐based exercises with diverse skin tones to further assess translational relevance and improve both physiological and operational fidelity.

In civilian settings, the implementation of WFWB transfusion remains limited by several barriers, including regulatory ambiguity, logistical challenges in donor identification and screening, liability concerns, variability in provider training, and difficulties related to storage, documentation, and traceability. ¹¹ The US Food and Drug Administration (FDA) requires comprehensive infectious disease testing, adherence to good manufacturing practice (cGMP) standards, and robust quality assurance systems for blood products. ¹⁸ These requirements are not readily compatible with the rapid, point‐of‐care collection and transfusion model inherent to WBBs at this time. These barriers highlight the need for proactive innovation required to safely activate a civilian WBB. For example, in our simulation we utilized Eldon cards which are not FDA‐cleared for definitive pre‐transfusion compatibility testing, but it is our hope that a similar ABO‐type rapid screening device will be approved in the near future. The time to address these barriers is now to prevent delays in civilian WBB success when it becomes absolutely critical.

In conclusion, our validated checklist and training video provide a foundation for structured education and proficiency assessment in WFWB collection and transfusion through simulation. Integration with existing trauma, prehospital, and disaster response curricula could strengthen regional and national preparedness for mass casualty and blood shortage scenarios. This framework can be applied across military and civilian WBB programs, ultimately improving outcomes for patients in hemorrhagic shock when conventional blood supplies are unavailable. Furthermore, collaboration between military and civilian agencies could foster the development of joint standards for WBB activation, donor screening, and WFWB administration. Future research should focus on validating this model longitudinally across diverse healthcare systems and operational environments, to determine strategies which mitigate the decay of acquired skills and bring those determined to be “not competent” to “competent.” Future work should also focus on expanding educational programs, advocating for state funding of WBB programs, and integrating WBB training into both prehospital and hospital systems.

FUNDING INFORMATION

This project was conducted under the Skills Determination, Decay and Delay (SD3) Study with the Combat Medical Skills Sustainment Consortium. This work was supported by the US Army Medical Research and Material Command (USAMRDC) under award Contract number W81XWH‐15‐9‐001(#MTEC‐21‐06‐MPAI‐072).

CONFLICT OF INTEREST STATEMENT

None of the authors have a conflict of interest to disclose.

Supporting information

Data S1: Supporting Information

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.