Hemorrhagic shock is both a local and systemic disorder. In the context of systemic effects, blood loss may lead to levels of reduced oxygen delivery (DO2) sufficient to cause tissue ischemia. Similar to other physiologic debts such as sleep, it is not possible to incur a significant oxygen debt and suffer no consequences for lack of timely repayment. While the linkage between oxygen debt and traditional organ failure (renal, hepatic, lung, and circulation) has been long recognized, we should consider failure in two additional linked and very dynamic organ systems, the endothelium and blood. These systems are very sensitive to oxygen debt and at risk for failing, having further implications on all other organ systems. The degree of damage to the endothelium is largely modulated by the degree of oxygen debt. Thus hypoperfusion is believed to begin a cascade of events leading to acute traumatic coagulopathy (ATC). This combination of oxygen debt driven endothelial damage and ATC might be considered collectively as “blood failure” due to the highly connected networks between these drivers. This article presents the implications of oxygen debt for remote damage control resuscitation strategies, such as permissive hypotension and hemostatic resuscitation. We review the impact of whole blood resuscitation and red blood cell efficacy in mitigation of oxygen debt. At last, this article recognizes the need for simple and durable, lightweight equipment that can detect the adequacy of tissue DO2 and thus patient needs for resuscitative care. Point‐of‐care lactate measuring may be a predictive tool for identifying high‐risk trauma patients and occult shock because it provides information beyond that of vital signs and mechanism of injury as it may help predict the level of oxygen debt accumulation and need for resuscitation. Serial measurements may also be valuable as a tool in guiding resuscitative efforts.

The Trauma Hemostasis and Oxygenation Research (THOR) Network has developed a consensus statement on the role of permissive hypotension in remote damage control resuscitation (RDCR). A summary of the evidence on permissive hypotension follows the THOR Network position on the topic. In RDCR, the burden of time in the care of the patients suffering from noncompressible hemorrhage affects outcomes. Despite the lack of published evidence, and based on clinical experience and expertise, it is the THOR Network's opinion that the increase in prehospital time leads to an increased burden of shock, which poses a greater risk to the patient than the risk of rebleeding due to slightly increased blood pressure, especially when blood products are available as part of prehospital resuscitation.The THOR Network's consensus statement is, "In a casualty with life-threatening hemorrhage, shock should be reversed as soon as possible using a blood-based HR fluid. Whole blood is preferred to blood components. As a part of this HR, the initial systolic blood pressure target should be 100 mm Hg. In RDCR, it is vital for higher echelon care providers to receive a casualty with sufficient physiologic reserve to survive definitive surgical hemostasis and aggressive resuscitation. The combined use of blood-based resuscitation and limiting systolic blood pressure is believed to be effective in promoting hemostasis and reversing shock".

The Blood Far Forward (BFF) research program was established to conduct blood product efficacy and safety studies, donor performance studies, and research on optimal training methods to improve the safety of blood collection and transfusion performed by Norwegian Naval Special Operation Commando soldiers. The use of intravenous fluids for volume replacement during hemorrhagic shock is controversial, but it is currently the standard of care. In the far-forward environment, large volume resuscitation for massive bleeding is a great challenge. Crystalloid and colloid solutions add weight and bulk to the medic's kit, require temperature sensitive storage, and should be warmed before infusion to prevent hypothermia. Excessive use of these solutions causes a dilutional coagulopathy, acidosis, and potentially increased inflammatory injury compared with blood products. Type-specific whole blood from an uninjured combat companion on the other hand is almost always available. It is warm, replaces intravascular volume, and provides oxygen delivery and hemostatic capacity to prevent or treat shock and coagulopathy. Whole blood may be ideal for the resuscitation of combat casualties with hemorrhagic shock. BFF program pilot studies on use of platelet-sparing leukoreduction filters, whole blood transport tolerance, donor performance, and autologous reinfusion of 24-hour ambient temperature stored whole blood have been performed and suggest the feasibility of expanding whole blood use in resuscitation. If successful, the BFF program will change tactics, techniques, and procedures with a new lifesaving capability.

BACKGROUND:To provide whole blood on the battlefield can be a challenge, but a buddy system protocol is both an elegant and the only currently available means to supply blood to a Special Forces team in far-forward locations. Our aim was to investigate donor-safety associated with such a protocol. METHODS:This study was a randomized, doubleblinded, controlled trial that aimed to evaluate the immediate effects of a 450 cc blood donation on physical performance in fatigued and dehydrated Special Forces soldiers. The primary outcome variables were absolute and relative maximal oxygen uptake (VO 2max ), exercise tolerance time (ETT) and heart rate (HR). RESULTS:Relative VO 2max decreased by 7.1% in the donation group between pre and posttest, compared to no change in the control group. Absolute VO 2max decreased by 11.2 and 3.6% between pre and posttest in the donation and control groups, respectively. Mean ETT in the donation group was on average 92 seconds shorter compared to baseline, which represents a decrease of 9.5%.CONCLUSION: Donating blood after a week of strenuous physical activity is feasible for Special Forces personnel. While the donation results in some diminishment of VO 2max , a 3.6%-11.2% decrease in relative VO 2max , and in elevation of submaximal HR levels highly trained personnel continue to perform well both at both sub-maximal and maximal effort levels. INTRODUCTIONK nowledge gained by medical practitioners in military conflicts over the last decade has contributed to significant changes in transfusion strategies addressing traumatic hemorrhagic shock.1 The transition from a crystalloid and/or colloidbased resuscitation approach to one that is blood-based is reflected in the fluid preferences for resuscitation of hemorrhagic shock recommended in the recent Tactical Combat Casualty Care (TCCC) guidelines. TCCC guidelines now recommend that whole blood (WB) be used as the primary resuscitation fluid. 2 This is also a current trend in the civilian EMS services in several countries. 3 And an increasing number of NATO and other allied nations are implementing TCCC guidelines in recognition of the published improvements in the survival of severely injured combat wounded over the course of the decade-long conflict. The guidelines have undergone continuousFrom the

Military experience and recent in vitro laboratory data provide a biological rationale for whole-blood use in the treatment of exsanguinating hemorrhage and have renewed interest in the reintroduction of fresh whole blood and cold-stored whole blood to patient care in austere environments. There is scant evidence to support, in a field environment, that a whole blood-based resuscitation strategy is superior to a crystalloid/colloid approach even when augmented by a limited number of red blood cell (RBC) and plasma units. Recent retrospective evidence suggests that, in this setting, resuscitation with a full compliment of RBCs, plasma, and platelets may offer an advantage, especially under conditions where evacuation is delayed. No current evacuation system, military or civilian, is capable of providing RBC, plasma, and platelet units in a prehospital environment, especially in austere settings. As a result, for the vast minority of casualties, in austere settings, with life-threatening hemorrhage, it is appropriate to consider a whole blood-based resuscitation approach to provide a balanced response to altered hemostasis and oxygen debt, with the goal of reducing the risk of death from hemorrhagic shock. To optimize the successful use of fresh whole blood/cold-stored whole blood in combat field environments, proper planning and frequent training to maximize efficiency and safety will be required. Combat medics will need proper protocol-based guidance and education if whole-blood collection and transfusion are to be successfully and safely performed in austere environments. In this article, we present the Norwegian Naval Special Operation Commando unit-specific remote damage control resuscitation protocol, which includes field collection and transfusion of whole blood. This protocol can serve as a template for others to use and adjust for their own military or civilian unit-specific needs and capabilities for care in austere environments.

Randomized, controlled, double-blinded prospective trial study, level 1.

BACKGROUND The provision of transfusion support to isolated military or civilian projects may require the use of an emergency donor panel (EDP) for immediate warm fresh whole blood (WFWB). The aim of this short discussion article is to raise and resolve some of the practical aspects for the nonspecialist faced with the emergency collection of WFWB whole blood in the austere medical environment (AME). METHODS AND RESULTS A proposed field EDP questionnaire and triage tool (QTT) is presented. It is designed for the hostile, remote, or austere environment that falls outside normal regulated supply of cold‐stored blood products or removed from trained blood collection personnel, where collection may fall to an isolated medical provider. The tool has been drafted based on review of existing guidelines and consultation with practitioners. It serves as a point of reference for local guidelines and has yet to be validated. CONCLUSIONS The use of the EDP is associated with risk; however, it remains the simplest method of providing rapid transfusion support. The best way to manage the risk is to brief and prescreen blood donors before deployment. An abbreviated donor QTT can be an aide to decision making at the time of donation. The tool should be tailored to requirements and underpinned by policy and training.

In planning for future contingencies, current problems often crowd out historical perspective and planners often turn to technological solutions to bridge gaps between desired outcomes and the reality of recent experience. The US Military, North Atlantic Treaty Organization, and other allies are collectively taking stock of 10-plus years of medical discovery and rediscovery of combat casualty care after the wars in Iraq and Afghanistan. There has been undeniable progress in the treatment of combat wounded during the course of the conflicts in Southwest Asia, but continued efforts are required to improve hemorrhage control and provide effective prehospital resuscitation that treats both coagulopathy and shock. This article presents an appraisal of the recent evolution in medical practice in historical context and suggests how further gains in far forward resuscitation might be achieved using existing technology and methods based on whole-blood transfusion while research on new approaches continues.