Treatment of active hemorrhage, hemorrhagic shock, and prevention of re-bleeding is the name of your game in combat trauma. There are two big killers on the battlefield: severe brain injury and hemorrhage. You can’t do a lot about the former, but through preparation and attention to detail, you can significantly impact the latter. Assume every injured patient you receive has active bleeding until proven otherwise. Look at your watch when the patient arrives, and keep that ticking clock in mind during your initial trauma evaluation and resuscitation. The whole philosophy of damage control resuscitation (DCR) can be summarized by the observation that “Patients bleed warm whole blood, not just red cells. Therefore, we should replace this with warm whole blood or the equivalent, not cold and coagulopathic packed red blood cells, starting from minute one of the resuscitation.”

Hemorrhagic shock and exsanguination are responsible for a large number of deaths in civilian and military trauma, accounting for more than 80% of deaths in the operating room and nearly 70% of deaths in the first 24 h after injury. Fortunately, only approximately 10% of military trauma patient admissions will require a massive transfusion. Newer definitions of massive transfusion are being evaluated to better identify these patients earlier in the resuscitation process. These include rolling rate-based definitions, the “critical administration threshold” (CAT) of greater than 3 units of PRBCs in an hour. Others have used a similar approach, but broadened the definition to include 3 units of any resuscitation product. This group of patients who require massive transfusion will account for the majority of blood utilization in deployed military treatment facilities (MTF). The recent conflicts in Southwest Asia have been the major stimulus to the rapid development, evaluation, and acceptance of damage control resuscitation (DCR). Multiple authors have demonstrated improved survival by using increased amounts and earlier use of predefined ratios of blood products, early in the care of these severely injured patients, in both military and civilian settings with the goal of approximating what is provided by whole blood. Rapid processing and preparation of such a large amount of blood and blood products in a short period of time requires significant planning and prior coordination of personnel and dedicated resources to ensure delivery of these products in an immediate and sustained fashion.

Previous descriptions of the coagulopathy from trauma were based on laboratory data from the operating room, and the conclusion was that abnormal coagulation laboratory values were not found in the first hours after injury and were associated with dilution. However, we now know that at least 25% of trauma patients arrive at the trauma center with abnormal laboratory values suggesting a coagulopathy. However, by using the DCR approach, only 6% are clinically coagulopathic, but those patients have very high mortality rates. The coagulopathy of trauma is a separate entity characterized by nonsurgical bleeding that can occur with or without appropriate concentrations of coagulation factors. Therefore, it has become paramount to have strategies in place (DCR) to directly address this coagulopathy in the severely injured patient. Always assume that the severely injured casualty is coagulopathic on admission and should be treated accordingly.

The damage control concept has been available as an alternative approach to management of the exsanguinating trauma patient who becomes cold and coagulopathic during laparotomy since the early 1980s. In the 1990s several authors applied the term “damage control” to this surgical resuscitation strategy and delineated damage control into three separate and distinct phases . Phase one consists of the abbreviated laparotomy, with the addressing of life-threatening hemorrhage and gross bowel spillage. The second phase involves the restoration of the patient to “normal” physiology through correction of acidosis, hypothermia, and trauma-associated coagulopathy. Phase three involves the return to the operating room for definitive repair and reconstruction of injuries temporized during phase one. Phase three occurs after restoration of “normal” physiology is achieved. Damage control resuscitation (DCR) spans all three of these phases and adds the pre-hospital as well.

The concept of DCR evolved out of this same approach. In the patients anticipated to need a massive transfusion, we have developed the concept of a special type of resuscitation (damage control resuscitation). DCR is composed of three basic components : (1) permissive hypotension – maintain palpable distal pulses in an awake patient, (2) minimizing crystalloid-based resuscitation strategies (prevention of ongoing hypothermia and dilution), and (3) the immediate release and administration of predefined blood products (packed red blood cells, plasma, and platelets) in ratios (1:1:1) similar to that of whole blood or the actual delivery of whole blood when blood components are unavailable. This aggressive delivery of blood products begins prior to any laboratory-defined anemia or coagulopathy in patients who have been identified as having life-threatening hemorrhage. This approach directly attacks the entire lethal triad which is often present in this small group of patients who are seriously wounded. However, no resuscitation strategy will work unless you are simultaneously addressing the source of the lethal triad – hemorrhage, shock, and hypothermia.

In civilian and military trauma populations, several authors have shown a significant laboratory-based coagulopathy already present at the time of admission. This represents a complex interplay of both hypercoagulability and hypocoagulability due to immunoinflammatory and hemostatic responses to injury. Several terms have been proposed to describe this pathophysiologic response, including acute coagulopathy of trauma shock (ACoTS), acute traumatic coagulopathy (ATC), and trauma-induced coagulopathy. Furthermore, the characteristics of this coagulopathy can change over time, with early evidence of activation of Protein C and depletion of fibrinogen. The cause of these changes has further been defined as primary (endogenous) vs. secondary (exogenous) which may be driven by aspects of our resuscitative efforts. This coagulopathy is driven by the shock state and is associated with a sharp increase in mortality, which makes it one of the immediate focuses of DCR.

Thromboelastography (TEG) is an old technology now in a resurgence in several fields including cardiac surgery, transplant surgery, and of course trauma. As opposed to common coagulation parameters such as PTT, INR, and ACT, TEG provides rapid assessment of the entire coagulation system (absent in the endothelium) which gives significant assistance to the clinician combating the coagulopathy of trauma. While an early empiric platelet- and plasma-first approach during damage control resuscitation is key in preventing the propagation of this coagulopathy, TEG may be the next step in an individualized and directed resuscitation strategy . We advocate checking it early and as often as needed. A quick reference for TEG interpretation can be seen in Fig. 4.1.

Currently, most resuscitations start with a ratio-driven approach and transitions to TEG-based (goal-directed) when bleeding slows enough that laboratory values are returned in a reasonable time from. Thus resuscitation is neither solely ratio driven nor goal directed but rather a combination of both, based on the rate of bleeding and local logistics. For now, TEG still faces some hurdles in widespread implementation. It requires surgeons, emergency physicians, and anesthesiologists comfortable enough with its use to interpret and make decisions with the information TEGs provide. Fortunately, this skill is easily learned. Additionally, TEGs have been traditionally time and personnel intensive for laboratories as they require special instrumentation, calibration, and to be run in controlled settings where ambient environmental conditions including vibration of the table they are being run on must be held constant to yield valid results. Fortunately, advancing technology is overcoming these obstacles, and in the near future, point-of-care TEG devices may find their way into the armamentarium of pre-hospital care.

It may be difficult for you to rapidly identify this group of patients. While there are currently no uniformly accepted criteria to identify the patients who will benefit from DCR, several groups have developed scoring systems (using a variety of anatomic, physiologic, and laboratory variables) to correctly identify the patient who will likely require a massive transfusion. While each of these scoring systems is quite accurate, there are two scoring systems which are most applicable to the setting of a combat support hospital or forward surgical team (Table 4.1). Each of these scoring systems relies on physiologic data, and each has its own limitations. The ability to apply these scoring systems will depend on your resources at your MTF. It is important to note, however, that each of these scoring systems should be used to augment, not replace, a surgeon’s clinical gestalt and decision making. Many severely injured patients will obviously require DCR (the casualty with a systolic pressure of 50 and thoracoabdominal injures). However, many young patients in excellent shape will initially “fake you out.” These patients “look good,” right up until they undergo cardiovascular collapse. Trust your clinical judgment. You will find certain injury patterns help augment your decision making to initiate DCR (Table 4.2). For example, one experience-based rule used in the Baghdad CSH was to give one “code red” pack (4 units PRBC, 4 units FFP) per severely mangled or amputated extremity regardless of the initial clinical appearance. Be aggressive. In our opinion, it is better to start with an aggressive hemostatic resuscitation and then shut it off early, as opposed to waiting until you are certain a patient will require a MT and starting the hemostatic resuscitation late. To that end, scoring systems such as the revised Massive Transfusion Score are even being suggested as a marker to end MT if parameters correct at the 3- or 6-h mark. More investigation is needed, but you will remain safest if you keep in mind the philosophy “stay out of trouble as opposed to getting out of trouble.”

Another useful tool at your disposal to identify patients in need of DCR is noninvasive tissue saturation oxygen monitoring (StO₂). This technology utilizes commercially available infrared spectrometry devices that provide real-time measurement of tissue perfusion which can be invaluable to the provider during a resuscitation. Initial StO₂ levels <70% or >90% taken at the time of arrival to the emergency department have been shown to correlate better than many traditional markers of resuscitation (i.e., tachycardia, lactate, base deficit) to predict the need for blood product transfusion, increased ICU length of stay and mortality in trauma and ICU patients. Its use in a pre-hospital setting has shown similar correlation in a yet to be published series. It can also be useful for its continuous real-time feedback, allowing you to gauge response to resuscitation efforts as they are being performed .

Ideally, DCR will start at the point of injury with first responders and pre-hospital medical personnel. This pre-hospital care has been termed remote or forward damage control resuscitation (RDCR). It is incumbent upon the medical officers to teach and direct our combat medics on the basic tenets of DCR for application in the setting. Tactical combat casualty care principles teach that casualties with severe hemorrhage are to be transported with limited crystalloid infusion and permissive hypotension. The patient who is awake or has a palpable radial pulse does not need much, if any, crystalloid en route to higher levels of care. Therefore, the medic can focus on prevention of blood loss using hemostatic adjuncts (to be discussed in more detail below) and hypothermia prevention. As you can see, two of three important components of DCR are under the immediate control of the combat medics. The third aspect of DCR, the rapid delivery of blood products, is usually currently under the control of physicians at the medical treatment facility level though this border is starting to blur as well and warrants further discussion .

When injury occurs in a far-forward environment or in a combat situation where immediate evacuation of casualties may not be possible due to an unsecured threat, your “golden hour” may have run out long before the patient hits the door. Considering that the clock starts ticking at the time of injury, the earlier all DCR principles can be put in place to start addressing the lethal triad, the better chance we have of achieving a favorable outcome for the injured patient. This is especially important in the setting of delayed (>60 min) or prolonged (>6 h) evacuations. Stabilizing a casualty by providing limited lifesaving interventions, stopping visible bleeding with direct pressure, permissive hypotension, and EVAC as quickly as possible to the nearest hospital for medical care are being augmented by starting treatment at the point of injury with the principles of DCR. Many topics discussed in this chapter as they apply to DCR such as mechanical and injectable hemostatic adjuncts and even blood product administration can be done pre-hospital. Storage and shelf life of blood products is the primary limiting factor and will be discussed in more detail later in this chapter as it applies to fixed hospitals. Suffice it to say, pre-hospital availability of blood products is primarily limited to medical evacuation teams, where the blood components are based out of a hospital where it can be appropriately stored and sent out with them when massive transfusion is anticipated. This may also present a potential application for the use of drones. At present the only freeze-dried product that is field ready is plasma, which has been used successfully by The Israeli Defense Forces at the point of injury as well as by both German and French Role 2 and 3 hospitals in Afghanistan. Under a special IND, some elements of the US Special Forces are carrying dried plasma pre-hospital. It provides hope for development of other components, though these are still likely years away from widespread application in the USA. Commitment from medical providers to the concept that care starts at the point of injury in the pre-hospital environment with dedication of resources (both tangible and time for training) will be the only way to close this gap.