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Abstract
Introduction The US military has frequently used a ‘walking blood bank’, formally known as an ‘emergency donor panel’ (EDP) to obtain warm fresh whole blood (WFWB) which is then immediately transfused into the casualty. We describe the frequency of EDP activation by the US military.
Methods We analysed data from 2007 to 2015 within the Department of Defense Trauma Registry for US, Coalition and US contractor casualties that received at least 1 unit of blood product within the first 24 hours and described the frequency of WFWB use.
Results There were 3474 casualties that met inclusion, of which, 290 casualties (8%) required activation of the EDP. The highest proportion of EDP events was in 2014, whereas the highest number of EDP events was in 2011. Median injury severity scores were higher in the recipients, compared with non-EDP recipients (29 vs 20), as were proportions with serious injuries to the abdomen (43% vs 19%) and extremities (77% vs 65%). The median number of units of all blood products, except for packed red blood cells, was higher for WFWB recipients. Of the WFWB recipients, the median was 5 units (IQR 2–10) with a maximum documented 144 units. There were four documented cases of EDP recipients receiving >100 units of WFWB with only one surviving to hospital discharge. During the study period, there were a total of 3102 (3%) units of WFWB transfused among a total of 104 288 total units.
Conclusions We found nearly 1 in 11 casualties who received blood required activation of the EDP. Blood from the EDP accounted for 3% of all units transfused. These findings will enable future mission planning and medical training, especially for units with smaller, limited blood supplies. The lessons learned here can also enable mass casualty planning in civilian settings.
- ACCIDENT & EMERGENCY MEDICINE
- Adult intensive & critical care
- ORTHOPAEDIC & TRAUMA SURGERY
- Trauma management
Data availability statement
Data may be obtained from a third party and are not publicly available.
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- ACCIDENT & EMERGENCY MEDICINE
- Adult intensive & critical care
- ORTHOPAEDIC & TRAUMA SURGERY
- Trauma management
WHAT IS ALREADY KNOWN ON THIS TOPIC
The US military has been using an emergency donor panel (EDP; walking blood bank) when the demand for blood outstrips the available supply.
WHAT THIS STUDY ADDS
It remains unclear how frequently the EDP was used during the recent conflicts.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
Among US and Coalition forces, the EDP was necessary for 1 out of 11 casualties that received blood products.
Introduction
Background
In the landmark study by Eastridge assessing potentially survivable death on the battlefield, he found that 90% were due to haemorrhage.1 This has led to an aggressive surge in methods to enable early blood transfusion, including whole blood.2 Multiple studies support the time-sensitive nature of this intervention.3 Whole blood transfusion has a long history, but only in the last two centuries has been a method of haemorrhage resuscitation. Notably, whole blood was incorporated into medical practice in World War I (WWI) and World War II (WWII) to resuscitate US military members.
During WWI, both the Canadian and US military were at the forefront of warm fresh whole blood (WFWB) transfusion. Major Lawrence Bruce Robertson transfused casualties with WFWB by directly transfusing from the donor to the casualty.4 This was further made a sustainable intervention when Oswald Robertson and colleagues developed the collection bottle with the Rous-Turner solution of citrate and glucose.4
During WWII, cold-stored whole blood and lyophilised plasma were often transfused. Still, WFWB was transfused when needed. Churchill stated, ‘Whole blood was the only therapeutic agent that would prepare seriously wounded casualties for the surgery necessary to save life and limb’.5 These practices continued in the Korean War. Crosby discussed the importance of WFWB.6 Though due to an established blood bank in Japan and the USA, cold-stored low titre group O whole blood (CS-LTOWB) was used for the majority of transfusions.
The conflicts in Afghanistan and Iraq saw significant use of WFWB. Two studies showed increased survival compared with component therapy.7 8 While one demonstrated no benefit over component therapy.9 There have been over 10 000 WFWB transfusions since 2001.3 A recent study of WFWB transfusions showed a 6-hour early survival benefit.3
Between the 1960s and 1980s, whole blood fell out of favour to component therapy due to improved technology of blood fractionation and understanding of its component functions for various pathology; however, this practice had few supporting data for haemorrhage resuscitation.10 While civilian medicine shifted towards component therapy, military medicine continued to use fresh whole blood in massive transfusion cases due to the higher quality of red blood cells, platelets and coagulation factors and limitations with logistical support of components in the deployed setting.11
Data from the recent conflicts have suggested that whole blood, specifically WFWB, sometimes referred to as ‘buddy transfusion’ or the ‘walking blood bank’, but more formally an ‘emergency donor panel’ (EDP) provides the best outcomes.12 WFWB refers to the direct infusion of a donor’s blood into a patient shortly after donation without storing and separating blood components and after undergoing limited screening. Compared with reconstituted blood components, WFWB has higher clotting factor activity and less additive solution and is closer to physiological temperature.3 The use of WFWB is dependent on the EDP when stored blood is not available.13 The Committee on Tactical Combat Casualty Care recommends the use of CS-LTOWB as the first-line therapy for resuscitation after haemorrhage.14 This supply is limited, especially in forward-staged areas, and as such the use of EDPs is needed to supplement the blood supply when consumption outpaces available resources.15–17 During future large-scale combat operations, the required blood products may rapidly exceed supply.18 19 This concept is now re-engaged in civilian trauma systems with a Norwegian blood bank developing an EDP programme that enables rural hospitals, prehospital services and municipal healthcare services to initiate blood transfusion in massive haemorrhage when supplies are exhausted.20 The US military has extensive experience with the use of EDPs, yet the frequency in which this is needed remains unclear. Understanding this resource’s frequency of use will enable future mission planning, especially in conflicts where casualty volumes may be substantially higher than the recent wars.18 19
Goal of this study
We describe the frequency of EDP activation during the recent wars, from years 2007 to 2015, before the implementation of the CS-LTOWB programme.
Methods
Data acquisition
We requested all encounters within the Department of Defense Trauma Registry (DODTR) that had at least one intervention or assessment available within the first 72 hours after injury. The US Army Institute of Surgical Research regulatory compliance office reviewed protocol H-23-004x and determined our study met exempt category #4 criteria; thus, institutional review board approval was not required. We requested and were granted HIPAA waiver M-11013. The data were transferred under Defense Health Agency data sharing agreement 23-2977.
DODTR description
The DODTR, formerly known as the Joint Theater Trauma Registry, is the data repository for DoD trauma-related injuries.21 22 The DODTR includes documentation regarding demographics, injury-producing incidents, diagnoses, treatments and outcomes of injuries sustained by US/non-US military and US/non-US civilian personnel in wartime and peacetime (including humanitarian) from the point of injury to final disposition. Short-term outcome data are available for non-US casualties. The DODTR comprises all patients admitted to a Role 3 (fixed-facility) or forward surgical team with an injury diagnosis using the International Classification of Disease 9th Edition (ICD-9) between 800 and 959.9, near-drowning/drowning with associated injury (ICD-9 994.1) or inhalational injury (ICD-9 987.9) and trauma occurring within 72 hours from presentation.
Analysis
We performed all statistical analysis using Microsoft Excel (V.365, Redmond, Washington, USA) and JMP Statistical Discovery from SAS (V.17, Cary, North Carolina, USA). We presented continuous variables as means and 95% CIs and compared them using the t-test. Non-parametric continuous variables and ordinal variables are presented as medians and IQRs and compared using the Wilcoxon rank sum test. Nominal variables are presented as percentages and numbers and compared using the χ2 test or Fisher’s exact test depending on the expected cell counts.
Variables and case selection
We analysed data from 2007 to 2015 to include US, Coalition and contractor casualties that received at least 1 unit of blood product within the first 24 hours and described the frequency of WFWB use. We defined serious injury to a body region as an Abbreviated Injury Scale ≥3.23 24 A massive transfusion was defined using ≥10 units of whole blood and/or packed red blood cells (PRBCs) (standard definition) within the first 24 hours and a submassive transfusion was defined using ≥3 units of whole blood and/or PRBCs within the first 24 hours as noted by our previous work.25 We included only US military, Coalition military and US contractor casualties that required at least 1 unit of blood to ensure homogeneity among the Medical Rules of Eligibility. We exclude casualties from 2016 forward since that was the implementation of the CS-LTOWB programme.26 Since the registry does not delineate the source of the blood product, we operated under the assumption that all whole blood administered prior to the CS-LTOWB programme implementation was the result of a WFWB transfusion.
Results
Within our primary dataset, there were 48 301 documented encounters, of which 3474 met inclusion for this analysis. Of the 3474, there were 290 casualties (8%) that required activation of the EDP. The highest proportion of EDP events was in 2014 (Figure 1), whereas the highest number of EDP events was in 2011 (Figure 2). The ages and proportion of males were similar between recipients and non-recipients. There were more US military recipients (84% vs 73%) whereas there were fewer contractors (4% vs 10%) and Coalition recipients (12% vs 17%). Median injury severity score (ISS) was higher in the recipients, compared with the non-recipients (29 vs 20), as were proportions with serious injuries to the abdomen (43% vs 19%) and extremities (77% vs 65%, Table 1).
Proportion of casualties that received blood from an emergency donor panel by year. EDP, emergency donor panel.
Total number of emergency donor panel activations by year. EDP, emergency donor panel.
Demographics of EDP recipients versus non-recipients
Median crystalloid volumes were higher for EDP recipients. The median number of units of all blood products was higher for recipients as well (Table 2). Of the EDP recipients, the median was 5 units (IQR 2–10) with a maximum documented 144 units. The most blood products transfused to a single patient were 331 units of PRBCs, 48 units of platelets, 155 units of cryoprecipitate and 358 units of plasma and the patient did not survive to hospital discharge. There were four documented cases of EDP recipients receiving >100 units of WFWB with only one surviving to hospital discharge. During the study period, there were a total of 3102 (3%) units of WFWB transfused among a total of 104 288 total units.
Comparison of 24-hour blood product consumption among EDP recipients and non-recipients
Discussion
EDP activation showed a positive trend from 2007 to 2015 by proportion, though the total number of activations has dwindled since its peak in 2011, which generally mirrors the operational tempo of combat activity and thus medical support infrastructure in theatre. The increase in the proportion of EDP could be due to the increased preparedness of the team in response to blood supply depletion as well as a growing body of literature that suggests WFWB transfusion has favourable outcomes.12 Recipients of EDP were more commonly military personnel and sustained injury from explosives and firearms, which in turn resulted in higher injury severity scores. These injuries often result in life-threatening haemorrhage and require massive resuscitation, rapidly consuming stored blood products, requiring the activation of the EDP. Even during times of low-intensity conflict, EDP had to be used as even one severely injured casualty may outstrip supplies. Specifically, injuries to the thorax, abdomen and extremities can damage large blood vessels, causing patients to quickly exsanguinate. EDP activation is often a result of blood supply depletion, due to multiple users of blood products or severe haemorrhage. In the latter case, the EDP recipient may already carry an unfavourable prognosis, demonstrated by the higher ISS, before EDP activation; therefore, these groups have higher mortality rates. EDP recipients also received more crystalloids and colloids, platelets, cryoprecipitate and plasma than non-recipients. Contrarily, EDP recipients received less PRBC. The lower use of PRBC is likely due to a combination of receiving WFWB since the PRBC storage was likely depleted but also potentially fresh blood having an increased ability to oxygenate tissue when compared with stored red blood cell.27 28
EDP carries with it additional challenges which are often not highlighted in previously published papers. The process of activating the EDP takes time. It also takes away resources from the medical treatment facility as they must now screen and obtain WFWB for transfusion.16 17 Moreover, in fixed locations, a limited screening is performed, though the donor pool is likely low risk due to medical screening of military personnel before entering the theatre. A study on 2222 samples of fresh whole blood from military donors in 2003–2005 revealed an infection rate of less than 0.2%, most commonly hepatitis C and HIV.11 Rarely, unscreened donors may also participate in EDP.29 However, we must acknowledge that even prescreened donors may become disease carriers in the time between screening and donation. In the military deployment setting, EDP donors are also limited by number and occupation since teams are not selected based on blood compatibility. Nonetheless, EDP is likely to become more common and serve as a source of whole blood during resuscitation emergencies. Our data provide insight into the activation of EDP with respect to frequency, population, mechanism of injury as well as survival after activation is necessary. This information can help with planning for deployment and preparation of an EDP where explosive and firearm injuries to the thorax and abdomen are likely in an austere setting. For example, it may be logistically favourable to train non-medical personnel to collect WFWB when needed.
This analysis is performed on data prior to the initiation of low titre group O whole blood protocol and may not be appropriate to extrapolate health outcomes after 2016. We operated under the assumption that EDP used WFWB transfusion; however, we do not have data on the exact content, condition or amount of the infusion. More detailed study and record keeping of transfusions would be helpful in future preparation of trauma resuscitation in circumstances where supplies are limited. We also lack data on the current operational environment at the time, available resources, the ability to resupply, as well as the number of casualties that were presented at the time. Such factors would aid in the development of better prediction tools. Additionally, we excluded humanitarian and partner force casualties due to the varying conditions of the medical rules of eligibility which may have skewed the use of an EDP, or blood products all together. As such, these data should be viewed considering that exclusion as it may not apply to theatres of operation where humanitarian and partner forces make up a large proportion of the casualties. Despite DODTR being a valuable resource for assessing trauma-related injury in military medicine, there are some limitations and potential biases. Data from DODTR are collected from hospitals and care teams that have varying capabilities and standards of care, which may introduce confounding variables that cannot be measured. Data entry can also be incomplete or skewed due to differences in workload. Military personnel have a higher representation in this data set, this could be due to medical rules of engagement excluding certain populations. Therefore, this analysis may not be appropriate for application to the civilian or non-combat setting. The database does not provide details on the exact diagnosis and treatment, as well as pre-existing conditions. Post-treatment follow-up is also not available.
Conclusions
We found nearly 1 in 11 casualties who received blood required activation of the EDP. Blood from the EDP accounted for 3% of all units transfused. These findings will enable future mission planning and medical training, especially for units with smaller, limited blood supplies. The lessons learnt here can also enable mass casualty planning in civilian settings.
Data availability statement
Data may be obtained from a third party and are not publicly available.
Ethics statements
Patient consent for publication
Acknowledgments
We would like to thank the Joint Trauma System Data Analysis Branch for their efforts with data acquisition.
References
Footnotes
X @FisherAD1, @armyemdoc
Contributors CYL performed the literature search and drafted the initial manuscript. JH conceptualised the idea and provided critical revisions to the manuscript. ADF, JAR, JBC and MDA provided key subject matter expertise and performed critical revisions of the manuscript. SGS conceptualised the idea, performed the data analysis and is the overall principal investigator on the dataset from which this study was derived. All authors contributed substantially. CYL and SGS act as guarantors and accept overall responsibility for the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Disclaimer The views expressed in this article are those of the authors and do not reflect the official policy or position of the Uniformed Services University of the Health Sciences, US Army Medical Department, Department of the Army, Department of Defense or the US Government.
Competing interests ADF, JAR, JBC, MDA and SGS have all received grants from the Department of Defense for other research.
Provenance and peer review Not commissioned; externally peer reviewed.