There is considerable data on injury cause and location for US military forces in conflicts from World War I all the way to the most recent decade of war in Iraq and Afghanistan [1]. It can be reasonably extrapolated that the armed forces of other first-world nations experienced similar injuries over the same time period, both in the cause and affected parts of the body. Far less data exists on the injury patterns experienced by the civilian populations in these same conflicts, or for the combatants representing guerilla armies or insurgent forces not tied to a specific nation. Nevertheless, some general observations can be made on the evolution of wartime injuries for these various groups. For all of these groups, it is important to consider the rise in use of the improvised explosive device (IED) as a cause of injury in the modern era to be of equal or greater or importance than traditional weapons of war.

Nowhere is the shift to IED-related injuries more apparent than for the armies of developed nations. During World War II, a third of injuries were due to gunfire, with the remaining majority coming from mortar rounds, artillery, and grenades. In more recent conflicts in Iraq and Afghanistan, gunfire still accounts for a quarter of injuries, but two-thirds of injuries are now due to IEDs. The injury location and severity have also evolved. Although extremity injuries have always been prevalent, they are now much more likely to be traumatic amputations due to IED blasts rather than simple gunshot or fragment wounds. Significant penetrating injuries to the thorax and abdomen are less common, which is easily explained by the widespread use of high-quality body armor in these areas. Many potentially catastrophic exposures to IED blasts result in no fatalities due to the use of heavily armored vehicles, although traumatic brain injury of varying degrees is quite common for the occupants of these vehicles, as the blast can still easily overturn the vehicle.

In contrast, the civilian population and guerilla or insurgent forces can be considered together, as they often uniformly lack any sort of body armor, helmets, or armored vehicles. For these groups, wartime injuries can and do cross the entire spectrum. In the absence of any protective equipment, exposure to an IED blast results in more battlefield fatalities before these individuals can be brought to any level of medical care.

Preoperative evaluation of wartime casualties begins with ensuring that they can be safely treated by the surgical team. For friendly forces, this includes having a security team remove any weapons, ammunition, and other potentially dangerous items, preferably at a point prior to entering the medical facility. This security search should also look for unexploded ordinance (i.e., an unexploded grenade), which the casualty may not even be aware of depending on the extent of their injury. This search and clearing phase is even more critically important in the case of civilians and insurgent fighters, who are essentially indistinguishable from each other. It would be a simple matter for an insurgent to present a real or simulated injury in order to gain access to the medical facility, and then detonate concealed explosives or attack the health care team with hidden weapons.

Patients may arrive via ground vehicle or on aircraft, although those being transported by air are often met by a ground vehicle at the runway or helipad for final transport to the medical facility. The extent of post-injury pre-hospital care varies greatly by the skill levels of the individuals in the field, combined with their available supplies, and the extent of ongoing hostilities. In the event of active fighting, the priority will be on protecting the fighting forces and enabling medical evacuation instead of rendering care. Likely pre-hospital interventions include obtaining intravenous access and administering crystalloids, or sometimes packed red blood cells. Occasionally, advanced airways will also be placed in the field, whether intubation with an endotracheal tube (ETT) or percutaneously with cricothyroidotomy. For any in-situ advanced airway encountered, it is important to confirm that it is in the trachea. As would be expected, airway devices placed in field conditions have a higher failure rate than those placed in a medical facility. Confirmation should include the presence of end-tidal CO₂ and bilateral breath sounds, with the understanding that a pneumothorax or hemothorax might obfuscate the latter finding. For patients with facial or head injuries, sometimes advanced airways are placed in the field preemptively, despite the patient having a normal level of consciousness and adequate minute ventilation without signs of respiratory distress. In these instances, if the advanced airway from the field is not found to not be in the trachea, consideration should be given as to whether it needs to be urgently replaced.

Unless the patient is in respiratory or cardiac arrest on presentation, securing the airway without patient resistance is usually contingent on first obtaining intravenous (IV) access and administering the appropriate anesthetic and muscle relaxant agents. As with other trauma scenarios, one or more short, large-bore peripheral IV catheters are the most desirable form of initial access. However, in the patient with extensive injuries including multiple traumatic amputations as may be seen with IED blast exposure, peripheral IV access may not be available. These patients are often the ones most in need of early aggressive resuscitation with blood products, so IV access is a high priority. If central venous access is required, an introducer of at least 8.5 French diameter with one or more side arms should be used instead of long, multi-lumen catheters of smaller diameters. For central venous cannulation, any site where access may be obtained quickly is suitable, although there are advantages and disadvantages to each. The internal jugular vein is the easiest for the anesthesia provider to access, but it may be unavailable due to the presence of a cervical collar. The subclavian vein is also an option, although the haste with which these lines are placed in a trauma setting may increase the risk of known complications such as non-compressible vessel injury and pneumothorax. The femoral vein does offer some advantages in the trauma setting:

Once IV access is established, or immediately in the case of cardiac or respiratory arrest, the anesthesia provider’s attention can turn to securing the airway. Indications for endotracheal intubation remain the same as other non-wartime trauma patients. All of these patients should be considered to be at increased risk for aspiration regardless of the timing of their last oral intake, so some version of a rapid-sequence intubation is recommended. It should be expected that any casualty exposed to an IED blast is at risk for cervical spine injury, so those patients should have airway management conducted with manual in-line cervical spine immobilization, regardless of whether they arrive to the medical facility with a cervical collar and other spinal precautions in place. Well-functioning suction and tools for managing difficult airways should be readily available at this time, to include the Eschmann tracheal tube introducer (aka bougie) and other adjuncts such as a video laryngoscope and/or a lighted intubating stylet. Once the patient is intubated, or for patients who arrive with an advanced airway in place, it is recommended to place them on mechanical ventilation in the preoperative phase in order to maximize the ability of the team to focus on other aspects of the patient’s care. Most patients arrive tachypneic as an adaptive response to the trauma and shock. Respiratory rates should be maintained (at least 20 breaths per minute) on the ventilator and then adjusted as blood gas or end-tidal CO₂ readings become available.

Drugs to facilitate intubation for wartime casualties are similar to other trauma situations. Although any induction agent can be utilized, those with minimal hemodynamic effects are better suited for the trauma patient. In the absence of significant myocardial injury, Etomidate is hemodynamically comparatively stable as opposed to Propofol and the barbiturates. Ketamine is also an option, although the expected small increase in sympathetic tone to help support the blood pressure is usually not seen in significant trauma, as these patients already have high sympathetic output. For the severely injured patient, the expectation would be a single endotracheal intubation at the first medical facility providing surgical care, with the ETT remaining in place through most of the critical care phase of the patient’s recovery, to include early follow-up surgeries. Therefore, relative contraindications to succinylcholine such as use more than 24 h after a significant burn or spinal cord injury generally will not apply to this population. If succinylcholine is used to facilitate the intubation, it will likely be of benefit to administer a longer-acting nondepolarizing neuromuscular blocking agent once the airway is secured.

Concurrent with appropriate airway management and following establishment of IV access, volume resuscitation must begin for severely hypovolemic patients with significant blood loss. The later section on transfusion medicine will address issues such as the ratios of blood component therapy and the use of fresh whole blood. However, the preoperative phase is where aggressive resuscitation with blood products must begin for these severely injured patients, with the goal of minimizing the total amount of crystalloid infused. For patients deemed to be appropriate candidates for antifibrinolytic therapy, this is also the time to begin the initial bolus of tranexamic acid (TXA). If rapid transfusion devices are available, they should initially be used in the pre-operative environment, and then follow the patient into the operating room to continue the resuscitation. It is critically important to administer supplemental IV calcium as needed to offset the chelating effect of the additives to various blood products. If time allows, point-of-care testing can be utilized to monitor and maintain the ionized calcium level in the normal range. However, in the midst of a massive transfusion, it may be necessary to simply administer IV calcium empirically, particularly in the setting of new or worsening hypotension without other obvious causes.

For patients with traumatic amputations, the surgeons may desire to release the tourniquets in the preoperative period for a number of reasons. First, they may want to better assess the extent of vascular injury and whether there is ongoing blood loss. In addition, from an orthopedic standpoint, minimizing tourniquet time also decreases the risk of nerve injury. Since the anesthesia provider is usually ultimately responsible for maintaining the patient’s hemodynamics, it is critically important for the surgeons to communicate their intent to release a tourniquet. Likewise, the anesthesia provider should not consent to the release of a tourniquet unless the patient has adequate IV access to permit a massive transfusion, and the immediate availability of blood products to support that transfusion if needed.

Particularly with exposure to IED blasts, it is common for wartime patients to present with closed head injury and the risk of increased intracranial pressure (ICP). Closed head injury can be difficult to assess in the setting of other concomitant significant injuries. Blast victims with a Glasgow Coma Scale (GCS) score of less than 9 with one for both pupils fixed and dilated and asymmetric motor posturing are at the highest risk. In addition to standard efforts to avoid hypoxemia and hypotension, normocarbia should be maintained with a goal PaCO₂ of 35–40, unless there is a need to transiently hyperventilate the patient to acutely decrease the ICP in response to rapid clinical deterioration. In the absence of readily available POCT for arterial blood gases, an end-tidal CO₂ goal of 30–35 can be used for most patients. In addition, a bolus and infusion of 3 % saline can be administered, even to patients who are hypotensive, whereas the second-line agent Mannitol should not be used in the setting of ongoing hypotension and hypovolemia. If serum chemistries are available, the target serum sodium level is 155–160 mEq/L. Despite a long history of controversy in the literature, steroids are not currently indicated in the management of head injury [2]. Although aggressive measures are generally employed to prevent heat loss in trauma patients to prevent hypothermic coagulopathy, head injury patients are one subgroup who should not be allowed to become hyperthermic as a result of warming efforts.