The Beginnings of Military/Operational Medicine

Wilderness medicine practitioners and disaster, humanitarian, and nongovernmental organization workers venture into environments that are complex, often with unique geography, political/governmental systems (or lack thereof), and unfamiliar cultures; economic and resource situations may be constrained or desperate. These areas may be involved in conflict, so it is beneficial to have an understanding of the nature of combat casualty care.

The first “operational wilderness medicine” courses and training were created centuries ago by military forces. Operational and wilderness medicine requirements have shared a long and symbiotic relationship with exchange of information, lessons learned, and equipment between the military and those physicians and responders willing and able to work in austere environments. Much of the knowledge, both remotely and recently, has benefited emergency care in general and wilderness medicine in particular. Much of the equipment and expertise now used by the military have resulted from improvements and refinement of wilderness medicine professionals. One of the first wilderness medicine experts to document wilderness medicine knowledge was Ibn Al Jazzar (circa AD 895-979) a physician from the Medical School of Kairouan in what is now Tunisia, once known as Carthage, the home of Hannibal (circa 200 BC). He wrote the then landmark wilderness medicine manuscript, Zad El Mousa Fir-Wa Qaout El Hadhir (Provisions for a Voyager Traveling Afar and for the Day’s Subsistence).⁵⁶

The word for healer in ancient Greek was iatros, meaning remover of arrows. Whether removing arrows in ancient Greece or shrapnel in the 21st century, the unfortunate reality of conflict as part of the human condition requires health care providers to be involved in operational and military medicine. Since the beginning of recorded history, advice for medical response to be applied during conflict has come from those often noted for medical progress unrelated to conflict. Hippocrates (460-370 BC) is known as the Father of Medicine and for the concept, “First, do no harm.” He also gave the advice that “He who would become a surgeon should join the army and follow it.”

Early accounts of medicine in war came from the classic literature, such as Homer’s The Iliad and Virgil’s The Aeneid. The Romans learned from these wars and trained medics (medici vulnerarii); each soldier carried his own bandages, which is similar to the Improved First Aid Kit (IFAK) carried today by soldiers and wilderness trekkers. In these accounts, medicine was rudimentary. Medical intervention concentrated on basic issues of bleeding, infection, and injury. These were the leading early killers in war though the ages and remain so to this day.

Introduction

In ancient times any significant injury was likely to result in death. In the Revolutionary War, lethality of combat injury was 42%. In the Civil War, the combat mortality rate was 33% for persons wounded; this decrease was due to improvements made in evacuation from the field with an ambulance corps and surgical care closer to the field. Even with the horrors of chemical munitions and trench warfare, World War I showed a decrease in war injury deaths to 21%. Great strides were made in World War II, including antibiotics and blood/plasma replacement; however, the combat mortality rate remained high at 30%. Korea moved Mobile Army Surgical Hospitals to the front and was the first conflict to routinely use air transport to get injured soldiers to the surgeons. The Korean conflict mortality fell to 25%. Vietnam further emphasized quick evacuation to combat hospitals, but the mortality rate remained steady at 24%.⁵⁶ In Vietnam, fewer than 3% died after arrival at a combat hospital, attributed to meaningful medical interventions being made earlier.^28,29,34 Most deaths were due to hemorrhage and airway/breathing compromise. Desert Storm in 1991, with a short but very intense combat phase, recorded 159 deaths from 626 total traumatic injuries, for a mortality rate of 25%. Military medical leadership studied previous lessons and created a better medical field response. The rates of mortality in the current conflicts of Operation Iraqi Freedom and Operation Enduring Freedom are the lowest seen in the history of conflict. Combat lifesavers (first responders) and then combat medics are at the scene immediately and buy time for injured soldiers. The likelihood of coming home is over 90%^{24,28,29,34,40} (Table 26-1).

In addition, disease, nonbattle injury (DNBI) has been a constant concern for the field surgeon and medic. The outcome of many conflicts has been determined by DNBI. Athens fell to Sparta in 430 BC as a result of an unknown communicable disease. DNBI affecting the outcome of conflict played out again in the trench warfare of World War I, and DNBI was deadly even in the same region of Gallipoli where the British and Australians lost many soldiers to dysentery and other nonbattle injuries.³³ In the U.S. Civil War, for every death due to trauma, there were three deaths due to DNBI and starvation. In the Russian-Afghan war over the course of 10 years, the war’s outcome was influenced greatly by disease; some contend that Russia was “beaten by the bugs.”³⁷

Combat by its very nature is a chaotic, dynamic, and unpredictable environment in which military medicine must function well to save lives. The methods and technologic advances used to kill and maim have increased the numbers of injured and the seriousness of the injuries. The nature of war has become less focused on armed conflict between sovereign nations fought by professional militaries and become an undertaking of insurgents, child soldiers, and terrorists. Battlefields often have “no front lines,” and conflict is more dangerous for soldiers, as well as deliberately targeted noncombatant civilians; military medical providers are using new skills to care for these patients.

Forward military medicine, performed before reaching combat support hospitals (CSHs), shares attributes with wilderness medicine. These include minimal equipment, harsh climates, remote and austere settings, and sometimes primal conditions. In militaries of the past, operational and wilderness medicine were taught after initial training as “on-the-job training.” Today they are primary medical training and education.

Austere conditions typically connote an image of uncivilized remoteness, but they are also found in large populated areas where medical conditions may be impacted by armed conflict, supply shortages, bad weather, and impassable evacuation routes. For persons who deliver prehospital care on the battlefield, in disaster or humanitarian situations, whether urban or rural, working in the “wilderness” is the norm, not the exception.

Regardless of environment, combat units within a battle space require medical capability. This capability is also used for injured civilians and forces that have laid down their arms. As strong as military medicine is as a force multiplier, it is also often used as a national engagement tool to shorten conflict, because medicine’s center of gravity and power is science and humanity, not geography, religion, or politics. When used in this manner, medicine may enhance progress toward peace.⁶⁰

This chapter reviews a few lessons learned from military medicine, with the battlefield as the construct. The intent is to provide operational civilian health care providers an understanding of unique military medical capabilities, the continuum of care, and unique battlefield injuries, as well as describe some of the medical treatments and evacuation issues from the point of wounding to definitive medical care. We thank the hard work and sacrifice of military medical providers throughout history who have advanced medicine on every front and in many cases have forged a path for others to follow.

Combat Medicine Compared With Standard Civilian Prehospital Care

In conflict environments, completion of the mission and preserving one’s own forces take precedence. Medicine has a place in the tactical environment but is relegated to a secondary role at certain points. Mission-focused combat care is divided into three distinct classifications designed to support the mission: decrease loss of life using principles of triage, take care of immediate life threats with simple interventions of proved benefit, and save as many lives as possible through rapid evacuation. These phases of care do not normally rely on a complete assessment, physical examination or evaluation of past medical history, as might be expected in a secure location in a routine field emergency situation.^17,18

The first phase of care, also known as care under fire, can be thought of as any event in which one is called on to render aid in an uncovered, unsecure, or potentially life-threatening situation. One cannot and should not “treat in the street” in a hostile environment. The first action will be to return fire and take cover (or take cover and return fire if more appropriate). There are many reflexive and simultaneous actions that will take place in this phase if the soldiers have been trained and drilled to an adequate degree of fine muscle memory. If one is able to provide care in this phase, the clinical intervention is likely to be only the most basic, such as moving the patient to a covered area to avoid further injury or placing a tourniquet. The usual protocols for ABCs (airway, breathing, circulation) may be reordered to CAB in order to focus on the interventions most likely to have the greatest impact on outcome in the working time frame.⁶³

Care under fire may simply determine whether or not a person is still alive. Mortal wounds or conditions such as an unresponsive patient without a carotid pulse are circumstances in which cardiopulmonary resuscitation would not be performed. After this phase is over, it is important to not forget security issues. These are easily overlooked because of euphoria that may result from the relief of surviving, or the need to begin to care for one’s comrades.^18,63

Field medics have long noted that one of their most critical first actions is to provide a confident demeanor. If the casualty is alert and responsive, the medic asks, “Where are you hurt?” and uses words and body language to let the victim know, “I’ve got you, and we’re going to get you out of here.” This is important because the casualty will be trying to determine his or her survivability and prognosis from the medic’s reaction. Major Shon Compton (U.S. Army physician assistant) teaches, “If the mind quits or doubts its chances; the body soon follows …”

Tactical field care is rendered after the situation is secure and allows care to proceed. Depending on how quickly the patient is extracted, tactical field care may be the first care provided.

The next phase of care is casualty tactical evacuation, in which the patient is stabilized and transported to a more definitive level of care. Evacuation platforms most often are “nonstandard” and nonmedical vehicles that are quickly drafted into use for critical casualty evacuation (CASEVAC).

Scopes of Practice for Combat Lifesaver, Combat Medic

Injured soldiers are unlikely to see a physician at the point of wounding. The Army has taken the civilian trauma system lessons of the “golden hour” to the next stage in what it calls the “platinum 10 minutes,” using combat lifesavers and combat medics to provide initial response on the battlefield. Many military emergency physicians note that in that first few minutes, there should be no qualitative difference in the response to traumatic injury between the medic and the physician. Given the same aid bag, the same set of circumstances, and the same patient, the expectation is that the same immediate lifesaving interventions will be made.⁶³

Combat lifesavers are first responders that are sometimes called the “battle buddy” of the medic. They buy time for the patient after the initial trauma. Their primary military occupational specialty may be that of infantry, aviation, maintenance, or other military nonmedical specialty, but after the situation is secured, they offer an extra set of hands for the medic. In addition to basic first aid, they are able to provide such skills as to deploy nasopharyngeal airways, apply tourniquets, or perform needle chest decompression for breathing difficulty after a penetrating wound to the chest (Figure 26-1).⁵ They do not, however, initiate intravenous (IV) lines or perform certain other advanced skills.

FIGURE 26-1 Core skill requirements. ACLS, Advanced Cardiac Life Support; CLS, combat lifesaver; ECG, electrocardiogram; MD, physician; PA, physician assistant; RN, registered nurse.

The combat medic is also known by the designation 68W (68 Whiskey). The scope of practice of the combat medic is most analogous to an EMT-Intermediate, with some special skills training in combat operational medicine based on the security, sick call, and unit issues with which the medic must deal. Additional airway skills include use of an adjunct such as a Combitube or King LT device and surgical cricothyrotomy (see Figure 26-1). The 68W is also taught the skills of needle chest decompression and chest tube placement. The 68W has the ability, with special training, to place an IV or intraosseous line and in certain cases administer blood products. The 68W has additional training in management of shock, including resuscitation from hypotension and prevention of hypothermia. Because closed head injury, burns, and stress reactions are prevalent wounds of the Iraq and Afghanistan conflicts, combat medics are entrusted with the initial evaluations of these problems. If the patient cannot be evacuated in a timely fashion, the combat medic may initiate protracted care, to include the placement of a nasogastric tube and urinary catheter. Combat medics also have the capacity to perform limited primary care, using protocols for minor sick call problems, and assist with monitoring for DNBI. They are given training in international humanitarian law (Geneva Law) focused on the rights, duties, and responsibilities of combat medics in areas of armed conflict, as well as caring for detainees.

Levels of Care and Capabilities

Military Health System Echelons of Care

The continuum of care in the military extends from the point of wounding to a battalion aid station (BAS), usually staffed by a physician assistant and/or physician, to the forward surgical team (FST) to the CSH (Figure 26-2).²⁶ At each point of care, the level of surgical and holding capability increases. Military medical planning includes support at each of these levels.^3,27,31,54

FIGURE 26-2 Taxonomy continuum of health care capabilities.

(From Defense Medical Readiness Training Institute: Joint operations medical managers course guide, San Antonio, Tex, 2009.)

Level I

The first medical care a soldier receives occurs at Level I, which may begin at the point of wounding. Initially, these first responder actions are provided by soldiers with combat lifesaver training, and later with assistance from the combat medic. If the service member is transported to a BAS, care is augmented by a senior medic or physician assistant. Level I initiates triage, patient collection, resuscitative care, and medical evacuation to higher levels of care. If the injuries or illness are minor, treatment is given and the disposition is “return to duty.” If the care required is more than minor, the patient is evacuated to a Level II or Level III facility. The decision is made based on the security situation, distance, and nature of the injuries. The civilian equivalent is similar to a first responder ambulance squad with advanced skills.

Level II

Level II is broken down into Levels IIA and IIB. Level IIA is an expanded care hub for the BAS, called an area support medical battalion (ASMB); this is similar to an urgent care clinic. This level of care duplicates Level I and augments services, with limited dental, laboratory, optometry, preventive medicine, health service logistics, mental health services, and patient-holding capabilities. The ASMB can further evaluate a casualty to determine if evacuation to a CSH (Level III) is warranted. In remote locations, Level II facilities are often teamed with an FST, also designated as Level IIB, to provide initial damage control surgery. The FST has an orthopedic surgeon, two or three general surgeons, two anesthetists, and critical care nursing capability. It is configured to be able to complete 10 major surgeries per day. Level IIB is similar to an emergency department with emergency surgical services.

Level III

Level III may be a CSH, a hospital ship, or Air Force facility. These facilities are in the combat zone and are analogous to regional trauma centers, with a full complement of medical and surgical services. There are intensive care and patient wards. These facilities are modular and can expand from 44 to 248 beds. If the patient requiring rehabilitation or extended treatment can be evacuated in less than 48 hours, or will have a prolonged recovery time, he or she is evacuated out of the theater. Local national civilian patients are not evacuated out of the theater, and civilian care may require extended hospitalization and rehabilitation that was not initially planned.

Level IV

The backstop of theater military care is the regional trauma medical center. This facility is within the theater, but on the evacuation pathway out of the combat zone. Definitive care, rehabilitation, and medical specialty services are available. The average stay is short for patients not expected to return to duty. These patients are further stabilized and evacuated out of theater for continued care at a Level V facility.

Level V

Definitive care describes Level V (primarily continental United States/CONUS) care. The Department of Defense and U.S. Department of Veterans Affairs hospitals provide this care. There are mechanisms to increase bed space using civilian hospitals in the National Disaster Medical System if this is vital to the effort.

Medical planning considerations loom large in the military because of the effects of practicing in an area of armed conflict often exacerbated by austerity of the environment itself. At one time an afterthought, military medical planning is now routinely considered at mission planning events. As for any wilderness medicine expedition, the specific characteristics of military health service support are determined by the mission, the threat, intelligence, anticipated number of patients, duration of the operation, the theater patient movement policy, available lift, and hospitalization and movement requirements. Military medical planners are expected to have an understanding of all the areas below:

• Threats/medical intelligence considers opposing force actions; occupational, environmental, geographic, and meteorological; endemic diseases and psychological stressors; and weapons of mass destruction.

• Patient movement and all this entails from planning, equipping, and patient care perspectives often have the greatest impact on the structure of the health service support design. Delays in transport will require holding capability and more assets for care . As for any expedition, weather, terrain and distance contribute greatly to decisions.

• Preventive medicine and health surveillance

• Prevention of stress casualties—The medical system is responsible for care related to mental health issues; however, a great deal can be done to prevent problems through establishment of a collaborative relationship with unit leadership.

• Veterinary service—The working dogs, civilian livestock in humanitarian situations, and any local animal issues such as rabies or disease reservoirs need to be considered in planning. Working dogs, in particular, are critical to many missions, such as security. These animals are considered soldiers in every sense of the word and may need full trauma resuscitation, including blood transfusions.

• Dental readiness needs should be addressed before deployment. Dental pain is a frequent reason for movement to the rear in unprepared soldiers.

• Medical care for prisoners of war and detained personnel—The care for this population may be more labor intensive than anticipated due to previous lack of medical care and significant traumatic injuries.

• Mass casualty situations preparation

Theater Trauma System

Much of the improvement in survival rates in the Afghanistan and Iraq conflicts is directly attributable to implementation of a trauma system. In both military and civilian populations, large numbers of patient requiring treatment for trauma or illness are best served through a “system approach.” The best systems have a designated trauma system director who is responsible for data acquisition, critical review of collected records, development of medical policy and practice guidelines, and ongoing evaluation of medical resources utilization, including staffing.³⁷

Joint Theater Trauma Registry

The Joint Theater Trauma Registry (Figure 26-3) is a key component of the Joint Theater Trauma System and was implemented in November 2004. As would any civilian trauma system, it collects the usual demographic and mechanism of injury data points. In addition, it collects information on unique transportation solutions, protective gear, service affiliation of the injured, and some unique aspects of conflict injuries (e.g., chemical, nuclear). This information has been analyzed extensively to develop and improve clinical practice guidelines, protective measures, medical and nonmedical training and best practices for patient care from the prehospital resuscitation, to damage control surgery, through rehabilitative care. The data have a very high fidelity in the fixed facilities but are less complete directly from the field.^20,15,16,30

FIGURE 26-3 Joint theater trauma registry.

Field collection of information is more difficult to obtain due to communications problems, the chaotic and insecure environments inherent in combat operations, and initial care and evacuation by nonmedical responders. The military recognizes field collection of data as a critical link in combat care and is exploring many areas for improvement, if not full resolution of field data collection issues. The preliminary findings are the same as those found in civilian trauma systems; the solution needs to be simple, lightweight, fast, and easy to append to patient records.

The military has experimented with the Battlefield Medical Information System–Tactical (BMIST), an electronic data collection system. It is still the goal to use an electronic patient care recorder. Though relatively lightweight, the BMIST weighs 11.1 to 14.1 oz; every item in a combat medic’s aid bag increases difficulty in mobility and decreases treatment items. Currently, as a fail-safe method, a simple tactical combat casualty care (TCCC; also referred to as TC3 in other venues) card (Form DA 7656) is used and carried in the soldier’s IFAK. If the soldier is injured, this card is completed as best possible and moves with the patient to the treatment facility, where it is able to be scanned into the record. It is a better method of recording trauma data than was the previous field medical card (Figure 26-4).

FIGURE 26-4 Form DA 7656.

Unique Aspects of Military Triage and Other Considerations

As in civilian mass casualty situations, triage attempts to provide the greatest good for the greatest number of victims. In most cases, military triage categories mirror those for civilians: immediate, delayed, minimal, expectant. In military triage situations, the security situation is often grim, transportation may be delayed, and the triage category of wounded soldiers, who in a less dire situation might have a survivable injury, becomes “expectant.” In addition, the military trains for scenarios involving chemical, nuclear, and radiologic incidents to practice continued combat effectiveness. Triage and treatment may be delayed because of mission requirements. The apportionment of resources may be based on the need for mission success.

An interesting illustration of the need for continued combat effectiveness was described in World War II, where penicillin was first used extensively for wound infections. Penicillin was very effective in the treatment of sexually transmitted diseases (STDs), also seen in the military population. Because of its limited availability, penicillin was rationed and at times used first for those soldiers with sexually transmitted diseases rather than for the badly wounded, to keep the fighting forces at the front.⁵³

Military triage has a component related to international humanitarian law. Soldiers who have laid down their weapons are offered the same opportunity in triage for care and treatment of their combat-related injuries. Triage for persons experiencing an emotional stress reaction, with or without wounding, require disarming before care can proceed.

Clinical Applications of Lessons Learned

Soldier Medical First Aid Kits (Figures 26-5 to 26-7) and Warrior Aid and Litter Kit

Improved survival rates in the current conflicts have been evaluated to search for further improvements. The reasons given for the 90% survival, even with increased lethality of wounding agents, are improved personal protective equipment, adherence to TCCC precepts, faster evacuation, and better-trained medics. The IFAK (see Figure 26-5) was developed based on the continuous review of injuries and is carried by every deployed soldier. It contains the essential items to address the major causes of preventable combat death: compressible hemorrhage, airway compromise, and tension pneumothorax. The IFAK contains a combat application tourniquet (CAT), kaolin-impregnated rolled gauze (Combat Gauze) that promotes hemorrhage control, 15.2-cm (6-inch) compression dressing (Israeli Trauma Bandage), nasopharyngeal airway, and 8.9-cm (3.5-inch) 14-gauge IV catheter for needle chest decompression. Hemorrhage is the leading cause of combat death. Interestingly, combat injuries have remained relatively similar in distribution since the Civil War; extremity injuries are the most common.

FIGURE 26-5 Improved First Aid Kit (IFAK) components. MOLLE, Modular lightweight load-carrying equipment.

(From Army Medical Department Center and School: Briefing on Combat Equipment, 2007.)

FIGURE 26-6 World War II aid bag.

(From Army Medical Department Center and School: Briefing on Combat Equipment, 2007.)

FIGURE 26-7 M5 Vietnam aid bag. IV, Intravenous.

(From Army Medical Department Center and School: Briefing on Combat Equipment, 2007.)

A Warrior Aid and Litter Kit (Figure 26-8) is carried on vehicles, although it can also be easily dismounted and carried via shoulder straps to the point of wounding. The additional equipment increases a unit’s capabilities to provide self-aid/buddy-aid for multiple casualties and interventions for the three leading causes of death on the battlefield. Furthermore, it provides a military squad the ability to evacuate a nonambulatory casualty (folding litter) and increases survivability during dispersed operations (i.e., improvised explosive device [IED]/rocket-propelled grenade [RPG] attack on convoy).

FIGURE 26-8 Warrior Aid and Litter Kit (WALK).

(From Army Medical Department Center and School: Briefing on Combat Equipment, 2007.)

Hemostatic Agents and Tourniquets

I am afeard there are few die well that die in a battle; for how can they charitably dispose of anything when blood is their argument?

WILLIAM SHAKESPEARE, THE LIFE OF KING HENRY THE FIFTH

Tourniquets are the number 1 instrument that a medic can employ to lower the KIA (killed in action) numbers.

COMMITTEE ON TACTICAL COMBAT CASUALTY CARE

The U.S. Army Institute of Surgical Research in San Antonio, Texas, finds that one-half of those injured in combat suffer “potentially survivable” wounds. Eighty percent of these are hemorrhage. In these bleeding events, 30% are in the extremities and “compressible,” where a tourniquet can be used to stop bleeding; 20% are in the neck, groin, axillae, or areas where a tourniquet cannot be used, but pressure can be applied to stop bleeding; and thorax or abdominal account for the remaining 50%, where surgical intervention is necessary.^8,20,23

Jean Louis Petit, a French surgeon, developed a screw device in 1718. He coined the term tourniquet from tourner (to turn).⁶⁴ The earliest known usage of a tourniquet dates back to 199 BC. Tourniquets were used by the Romans to control bleeding, especially during amputations. These tourniquets were narrow straps made of bronze covered with leather (Figure 26-9). These look remarkably similar to the CAT (Figure 26-10) used today.

FIGURE 26-9 Roman tourniquet.

(Courtesy Science Museum, London. http://www.sciencemuseum.org.uk/broughttolife/objects/display.aspx?id=4304.)

FIGURE 26-10 Combat application tourniquet (CAT).

The CAT was selected after extensive testing and research. Other methods, such as a triangular bandage and sticks, can be used if a CAT is unavailable. The imperative is to occlude the distal pulse. It may take multiple tourniquets to accomplish obliteration of the pulse. Do not remove previously applied tourniquets if bleeding continues; tighten the tourniquet further if possible, or apply another tourniquet proximal to the first.⁶³

TCCC teaches to attempt to control all sources of bleeding and consider and assess for any bleeding not immediately detectable. The TCCC protocol for life-threatening compressible external hemorrhage or amputation is tourniquet application. The tourniquet is placed on the skin 5.1 to 7.6 cm (2 to 3 inches) above the wound. For neck, groin, and axilla hemorrhage, Combat Gauze is used. It is packed in the wound, and direct pressure is applied for at least 3 minutes. Then, a pressure dressing is placed over the wound site if possible. For anatomic reasons, a pressure dressing may have to be innovative. It is impossible to circle the neck with a pressure dressing because the blood supply to the brain and airway will be disrupted.

All tourniquet sites should be exposed and clearly marked using an indelible marker with the time of tourniquet application. A “T” drawn on the patient’s forehead is a common designation.

A bandage that stops bleeding has been sought for centuries. Combat Gauze, which is a kaolin-impregnated Kerlix gauze, is the best hemostatic dressing at this time. Other agents have been reviewed and/or used but had drawbacks. Factor concentrators, such as QuikClot, that removed water from blood, created a significant exothermic reaction, were difficult to use in some environments, and were difficult to wash out of wounds. WoundStat used concentrated clotting factors without a significant increase in temperature, but caused some tissue damage and embolic episodes. Mucoadhesive vehicles, such as HemCon, Chitoflex, TraumaStat, and Celox, were made of shrimp exoskeletons. Although tissue damage was not seen, the hemostatic properties were not as robust as those seen with Combat Gauze. Combat Gauze is a procoagulant supplement that uses gauze impregnated with Kaolin (active agent is aluminum silicate) and is the hemostatic dressing issued to the U.S. military for combat use. In the future, fibrin dressings and spray-on sealants may become available.^{1,13,22,44–46}

Combat Gauze may be used after the initial application of a tourniquet has stopped bleeding or if a tourniquet is not essential on inspection of the wound after the care under fire phase. It is vital to continually monitor bleeding if a tourniquet is placed or if other techniques are used, because these may become dislodged or the patient may start to bleed after fluids are replenished or the patient is warmed. Hypotensive resuscitation to avoid normalization of blood pressure and “blowing the clot” until surgical control is achieved is a key principle. Before releasing any tourniquet on a casualty who has been resuscitated for hemorrhagic shock, to ensure a positive response to resuscitation efforts, one should have applied a pressure dressing and be ready to reapply the tourniquet.

Tourniquets cause ischemia in the treated extremity. Release of a well-placed and functioning tourniquet after several hours releases lactic acid and potassium generated by anaerobic metabolism and cell injury. Before removal of a tourniquet that has been in place for any significant period of time, make sure the patient is well hydrated and as fully resuscitated as is reasonably possible, and consider adding 50 mEq of sodium bicarbonate to a liter of IV fluid for administration. Release the tourniquet slowly. If cardiac arrhythmias occur, reapply the tourniquet and wait to remove it until after further fluid resuscitation and sodium bicarbonate is administered. If the limb is “dead,” the overriding tenet is “life over limb.” Consider a fasciotomy (four compartment) in any lower extremity with extensive tourniquet time (over 2 hours).¹⁰

Control of bleeding is paramount in combat care. Adequate bleeding control may turn an “immediate” category patient into a “delayed” category patient, able to wait for secure transport. Tourniquets and hemostatic agents (QuikClot Combat Gauze) are the current best methods of bleeding control. Blind attempts at clamping vessels in bleeding wounds cause more damage than good and should be avoided. Bandages should be inspected frequently because they can hide continued bleeding.

The Airway in Combat

The protective equipment worn by the military is working well to decrease injuries to the thorax. However, the face remains relatively exposed, with the result that 10% to 15% of combat casualties sustain maxillofacial trauma. Penetrating facial/airway trauma often presents a frightening picture but is often manageable if taken one step at a time.

In emergency medicine, clinicians are always taught to control cervical spine (c-spine) movement by using a hard collar and immobilizing the patient on a spine board. However, this approach may cause further airway complications in a patient with significant penetrating facial trauma. Blunt forces cause c-spine injury in 2% to 6% of patients in civilian studies and may be up to 10% in patients with extensive blunt facial trauma. Unstable cervical spine trauma is uncommon in neurologically intact patients with penetrating (as opposed to blunt) force injuries.^12,48,51

In many cases, simple positioning or use of a nasopharyngeal airway will allow an adequate airway until definitive treatment is available. If the patient is able and wants to sit up, it is preferable to allow this rather than suffer an airway loss. The contraindications for combat nasopharyngeal airway placement are severe head or facial injuries, evidence of a basilar skull fracture (e.g., Battle’s sign, raccoon eyes, cerebrospinal fluid/blood from ears), or known coagulopathy. Loss of a marginal airway can occur quickly if medications with sedating properties are used, so it is best to defer these until medical personnel are ready to manage the airway. If pain medications are used, be prepared to take over the airway.¹⁰

The usual interventions are IV access, monitoring, suction, and supplemental oxygen. Before taking over definitive airway management for the patient, everyone should be ready to perform it and those with the most expertise should be in attendance. If sedation is required, IV ketamine in titrated doses allows the patient to maintain breathing and some protective reflexes. Difficulties arise from inadequate suction and bleeding into the field of vision. If oral endotracheal intubation is impossible, cricothyrotomy is performed. Alternatively, video intubation scopes are small, lightweight, and very portable and are a useful adjunct, although visualization is still difficult in situations with brisk bleeding or in the absence of suction. In environments where use of a laryngoscope could garner unwanted attention from the enemy, a cricothyrotomy might be necessary even if oral intubation is an option. In mass casualty situations, the threshold for cricothyrotomy is decreased due to time and resource constraints.

Hypothermia

Hemorrhage and trauma can be precipitating events for hypothermia. The combination of hypothermia (defined as core body temperature under 35° C [95° F]), acidosis, and coagulopathy put trauma patients at greater risk for multisystem organ failure and death. This triad was first described in 1982 as the “bloody vicious cycle.” Hypothermia itself inhibits coagulation. Under 32.2° C (90° F), hypothermia is life threatening by affecting cardiac and respiratory function. Hypothermia is seen commonly in trauma patients, even in environments where heat injury might seem more likely. The Joint Theater Trauma System noted that patients evacuated to the combat support hospitals were hypothermic, and the system developed a hypothermia clinical practice guideline, which is emphasized by the Committee on Tactical Combat Casualty Care and its training recommendations.^3,7,39

Prevention measures are protection from the environment, removal of wet clothing (blood or other fluids), keeping the patient covered, and using adjuncts such as the Hypothermia Prevention Management Kit (HPMK). The latter is especially useful during the CASEVAC phase, where prevention of hypothermia may be difficult due to altitude, flying with open doors, and the injury. The HPMK has a self-heating, four-cell shell liner that is able to sustain continuous dry heat, and a skull cap to keep the patient warm.⁶³ Also, if portable fluid-warming devices, such as the Thermal Angel Blood Warmer, are available, they should be used on all IV fluid sites. If adjuncts are unavailable, one uses whatever is at hand, such as dry blankets and sleeping bags. Wool blankets alone are not particularly good at keeping the patient warm, but a “hot pocket” has shown good results to prevent passive heat loss. This method puts the patient in a body bag, covered in two wool blankets and a space blanket, with an opening for an endotracheal tube.^2,10

Damage Control Surgery

The goal of damage control surgery is to prevent the physiologic derangements caused by trauma and severe hemorrhage. The surgery does not reestablish normal anatomy but is rather a planned series of surgeries to normalize function.

Damage control is a planned management of the patient with three defined phases:

This care continues as the patient is moved through the evacuation process to definitive care.^3,10,57

Blood

The U.S. Army clinical practice guideline for damage control resuscitation (with massive transfusion defined as >10 units of red blood cells [RBCs] in under 24 hours) was instituted in March 2006. It endorsed a 1 : 1 fresh frozen plasma (FFP) to RBC transfusion ratio with less emphasis on crystalloid use.^49,59,62

In most cases blood component therapy is used. However, in austere circumstances use of fresh whole blood (FWB) may be a way to augment the blood bank with “fresh” donors, especially if FFP and platelets are in limited supply or nonexistent.

There is some indication that FWB may blunt the inflammatory response and organ failure seen in hemorrhagic shock states. In addition, oxygen-carrying capacity and decreased hemolysis (associated with hyperkalemia) are seen with FWB.

Factor VIIa

Factor VII initiates the process of coagulation in conjunction with tissue factor, which is found on the outside of blood vessels and therefore is normally not exposed to the bloodstream. Upon vessel injury, tissue factor is exposed to the blood and circulating factor VII. Factor VII is activated to factor VIIa. Factor VIIa is a procoagulant that was first used in uncontrollable bleeding seen in hemophilia patients with factor VIII or IX deficiency and inhibitors against replacement coagulation factor.

Factor VIIa was first reported used for trauma in 1999 for an Israeli soldier in extremis due to a high-velocity gunshot wound with disruption of the inferior vena cava.⁴³ In the U.S. military, factor VIIa is used in uncontrollable hemorrhage with significant coagulopathy as an addition to FFP and packed red blood cells in a 1 : 1 ratio. Platelets are given if massive transfusion is necessary. Factor VIIA requires adequate platelets for optimal results. Acidosis must be corrected in order for it to work. There is a theoretic risk for deep vein thrombosis, pulmonary embolism, and myocardial infarction. However, prospective randomized trials and retrospective trials on combat wounded have not shown any increase in thromboembolic events.

Wounds

Combat wounds range from minor to devastating. All require meticulous care and can initially be deceiving as to extent. For the initial combat wound, the soldier takes antibiotics that are supplied in the combat pill packs. The usual antibiotic is moxifloxacin 400 mg orally (PO) once a day. If the soldier is unable to take oral medications, then cefotetan 2 g IV or intramuscularly (IM) every 12 hours (or ertapenem 1 g IV or IM) once a day is administered. Even though most soldiers have current immunizations, one must consider tetanus immunization status in all wounds. This is especially true in nonmilitary personnel. Antibiotic prophylaxis is included for any penetrating wounds to the eyes/globe.*

Wounds from blast injury include burns, tissue loss, and/or extensive maceration. These injuries should all be treated as though there is underlying structural injury until proved otherwise; these patients are often candidates for damage control resuscitation and surgery. Initially bleeding may be unimpressive, but it can increase with improvement in blood pressure, warming, and manipulation during exploration, debridement, and irrigation. Primary closure of wounds is rarely considered.^10,50 After debridement, the wound should be packed with rolled gauze. If necessary, the skin is sutured over the packing for tamponade of bleeding. This is a temporary measure for life-threatening bleeding until damage control resuscitation is under control.^3,10

Injuries to large arteries and veins need to be controlled and may require a tourniquet, pressure dressing, vascular shunt, or ligation. In initial damage control surgery, a nasogastric tube or IV tubing can be used as a temporary vascular shunt, and the aorta can be shunted with a small pediatric chest tube. If a shunt is performed and the patient is to be transferred, a tourniquet should be placed loosely (i.e., not tightened) proximal to the shunt for transport in case of shunt dislodgment. Similarly a nontightened tourniquet should be placed before evacuation after amputation to be prepared for bleeding.¹⁰

Unique aspects of blast injuries are the extensive damage and the path the blast may follow up the bone in an extremity. Although physicians are taught to spare as much tissue as possible during debridement, in blast/land-mine injuries a common problem is underestimation of the depth of the injury.

Wound Vacuum-Assisted Closure (VAC)

Wound care has been a defining characteristic of military medical care through the ages. The principles are cleansing, debridement, and elimination of effects harmful to the wound (such as wound cautery used in the Middle Ages and early Renaissance). In today’s battlefield, more soldiers survive blasts, high-velocity missile strikes, and other combat injuries because of better protective gear, highly trained combat medics, and faster evacuation to surgical care. These survivors have complex wounds with high probability of infection that are unable to be closed primarily. They require not only adherence to the basics, but new modalities and a team approach to care that involves physical and emotional care.^3,10,50,54

Wound VAC devices are used extensively with good results for massive wounds with tissue loss seen in combat injuries. Other circumstances that benefit from this therapy are pressure ulcers, partial-thickness burns, orthopedic injuries with tissue loss, skin grafts, and abdominal wounds that are left open after damage control surgery. This therapy can decrease healing time and reduce risk for infection and other complications. Commercial devices consist of a dressing that is fitted with a tube and attached to the wound VAC device.

Before use of the device, the wound is meticulously debrided, irrigated, and cleansed. A sterile sponge (or reticulated open-cell foam) is cut to fit inside the wound, the wound is sealed with a film to prevent leaks, and a suction tube is placed in the sponge. The opening of the tube through the skin is also sealed and connected to a wound VAC device. The suction pressures are usually 50 mm Hg to 200 mm Hg (average 125 mm Hg). The device is turned off for dressing changes.

For drainage, a wound VAC can be highly beneficial. The interval between dressing changes can be extended because the VAC drains fluids from the wound and leaves less media for bacteria. In cases that may compromise circulation because of edema, a wound VAC improves blood flow to the wound and surgical area.

Vacuum wound closure systems and their benefits as an important adjunct to modern combat wound care are discussed in the U.S. Department of Defense’s Emergency War Surgery,³ First to Cut: Trauma Lessons Learned in the Combat Zone,¹⁰ and War Surgery in Iraq and Afghanistan: A Series of Case Studies, 2003-2007.⁵⁴ These also describe field-expedient methods to produce a wound VAC system with available equipment.

Burns

Prehospital burn care is the same as that for civilians with a few additional considerations. The burn patient in a combat zone must be considered for additional injuries, wounds, hemorrhage, and possibly blast injury. If this is the situation, Hextend is used as per the shock protocols along with crystalloid (lactated Ringer’s) burn resuscitation. The amount of Hextend used should not exceed 1000 mL. The U.S. Army Institute of Surgical Research Burn Center, which serves as the U.S. Department of Defense burn center, developed a new fluid resuscitation “rule of 10” used for burns greater than 20%. It is based on current research regarding burn resuscitation.^10,21

Pain Management

Homer’s The Iliad has some of the first descriptions of war wounds and their treatment; pain relief was recognized as a principal tenet of combat medicine. The need remains the same today.

FIGURE 26-11 Achilles taking care of Patroclus.

(Courtesy Wikipedia. http://en.wikipedia.org/wiki/Achilles_and_Patroclus.)

Pain is a common manifesting symptom in injuries directly related to combat. In the deployed environment, there are also other more ordinary causes of pain, such as motor vehicle accidents, long periods in confined spaces, heavy personal protective equipment, and lifting and training accidents.^9,38

The military is performing ongoing research into pain relief on the battlefield. The challenges are distance, security situations that may delay transport, provider inexperience, and severity of the injuries.^9,38 Causalgia (reflex sympathetic dystrophy) was a common diagnosis seen after the Civil War, and chronic pain states are still seen today in patients without adequate pain management. Current studies indicate that the cause or exacerbation of post-traumatic stress disorder (PTSD) is related to poorly or untreated, unrelenting pain.³⁸

The standard is that all casualties with pain are given analgesia. The determinants of type and route of medication are as follows: (1) is the casualty conscious? (2) is the casualty able to fight? and (3) is there IV access?

At the point of wounding for severe pain, the combat medic (68W) is able to give morphine 5 mg in titrated doses IV (preferred), IO, or via IM injection. Oral transmucosal fentanyl citrate 400 to 800 mcg^6,32 is an alternative to morphine for use before arrival at a combat support hospital. Naloxone is available for respiratory depression. Promethazine 25 mg (IV/IM/IO) every 6 hours as needed has been added to the prehospital pain medication regimen to treat the nausea that is common with injury and often seen with narcotic administration. If the patient is treated with these medications, his or her weapon is secured and the patient is no longer able to fight. Splinting, positioning, and emotional support are provided as the patient is prepared for evacuation.

Military members in combat carry a combat pill pack, which is taken as soon as possible after injury or wounding. These are oral medications: meloxicam 15 mg (a cyclooxygenase-2-inhibitor selective nonsteroidal antiinflammatory drug) once a day and acetaminophen 650 mg (bilayer caplet) two pills every 8 hours. These medications were chosen for the ability to relieve moderate pain without causing platelet dysfunction or decrease in mental alertness. The soldier is still able to carry a weapon and able to fight if necessary. An antibiotic is carried in the combat pill pack and used for all open combat wounds. Currently the antibiotic of choice is moxifloxacin 400 mg PO once a day.⁶³

After arrival at a BAS, FST, or CSH, other medications and modalities are available. Low-dose ketamine is an excellent analgesic. In the future, intranasal ketamine may be an option¹⁰ Clonidine may be used in stable patients.^9,38 Peripheral nerve blocks and regional blocks (if trained personnel are available) offer excellent relief. A fascia iliaca block is useful for pain relief of injuries involving the hip, anterior thigh, and knee. This block is useful for fractures of the hip and proximal femur, especially before prolonged transport. Intercostal blocks are beneficial for chest wall pain after trauma, especially in the presence of rib fractures.

Telemedicine

Telemedicine has been used successfully to diagnose dermatologic conditions, send radiologic studies for interpretation, and give reports on patients being evacuated to higher levels of care. Combat medics in remote sites have used e-mail contact with their unit physician assistant or physician to make determinations of evacuation or therapy for ill or injured soldiers. The U.S. Army Medical Research and Materiel Command and the Telemedicine and Advanced Technology Research Center have worked on surgical robots and mentoring programs to assist in surgery. Colonel Bruce Adams has successfully experimented with camera observation and advice to combat medics for assistance in performance of surgical cricothyrotomy on manikins. Although telemedicine currently has limitations because of bandwidth, privacy issues, and urgency of trauma patient consultations, it holds promise for the future.⁴⁷

Casualty Evacuation (CASEVAC)

Wilderness medicine providers operating in conjunction with the military should be aware that evacuation platforms, both ground and air, are tremendously different when compared with the civilian evacuation system. Civilian evacuation platforms (ground and air) are generally equipped to provide en route care (oxygen, diagnostics, medications, communication with medical control) and are staffed with paramedics with advanced training. Military evacuation platforms are essentially patient transport platforms with very little en route patient care. The military places greater emphasis on casualty stabilization before evacuation because of this configuration. The military evacuation system is designed for speed of transport into and out of combat areas with active small arms fire. Hence, the ability of a lightweight, agile, fast, and rugged platform (ground and air) to enter and exit an active skirmish, while providing a modicum of safety to the patient and medical attendants, is vital. The speed and effectiveness of the military medical patient transport system are often overlooked; however, the success of the system is reflected in the less than 10% dead on arrival (DOA) rate seen in current conflicts.

At the point of wounding, the evacuation platform is more often going to be a tactical vehicle than any sort of ambulance. Due to increased use of IEDs and RPGs, most vehicles are armored or hardened. The space is very limited, so to the greatest extent possible, any control of bleeding, placement of tourniquets, and other medical procedures are accomplished before transport. It is also important to work with equipment such as litters to make sure they will fit in the vehicles. During transport, it is critical to ensure medical interventions, such as control of bleeding, remain intact. For the badly injured casualty, evacuation from the time and point of wounding to the closest and most appropriate initial care at an FST or CSH averages about 1 hour. If the determination is that there is a lesser injury, the patient can be taken to a BAS for a determination of injury and evacuated to a higher level later if required.⁵⁴

Casualty evacuation is a multifaceted transport system designed to enhance patient evacuation based on proximity of stage evacuation assets, not based on injuries. Regardless of the type of injury, a triage category and then an evacuation category will be assigned. During casualty evacuation planning, all platforms and locations are plotted to facilitate entry into the evacuation system.

Helicopters are used extensively for casualty transport. In combat situations, a white light, such as that in a laryngoscope, in the helicopter compartment may be forbidden. Because the doors are often left open for security reasons, protection of the patient from the wind and hypothermia becomes more critical.

If the patient is in a helicopter and the time to a CSH is not significantly greater than the FST, the decision may be made to go directly to the CSH. Although the FST has a great deal of surgical capability, its roles are lifesaving interventions and limited surgery to stabilize the patient to allow evacuation to the CSH.

Transportation after initial advanced-level care often involves an intubated (and possibly ventilated) patient. Sedation and analgesia are essential for these transfers. In addition, no paralytic agent should ever be given without a potent sedative. Some evidence suggests that the administration of sedation and pain relief may decrease the probability of later PTSD. Absent hypovolemia, a sign of inadequate pain and sedation may be persistent tachycardia. The airway and patient should be adequately prepared because loss of the airway during combat evacuation is a major life threat. Reestablishment in a limited space with inability to hear breath sounds may necessitate a surgical airway. The attendant in transfer must have sufficient medications and doses to keep the patient comfortable and sedated and be able to provide an airway if the patient is extubated. For the most critical airways, the endotracheal tube may be wired onto the teeth.¹⁰

For any ground or air transport, including longer transports such as aeromedical (Air Force flying hospital; C-17) transfer out of the combat zone, a pretransport check to ensure necessary medical items (e.g., oxygen, tourniquets, sedation, analgesia, antibiotics, IV fluids, decompression needles, urinal) is important because the transferring facility is responsible for the patient’s medical equipment needs during movement. A patient with a minimal pneumothorax or on positive pressure ventilation is susceptible to a tension pneumothorax during transport, so the attendant must be able to address this. Other possible causes, such as a kinked tube or mucus or blood clot in the tube, need to be quickly ruled out. It is difficult to evaluate a patient in a helicopter; if there is any question as to which side is under tension treatment, a 3.25-inch 14-gauge needle is inserted into the second intercostal spaces bilaterally. If there is a question of pneumothorax before transport, a chest tube should be placed before transport.

Any patient who has had a tourniquet placed in the field, is a postoperative amputee, or has had a vascular repair is at risk for hemorrhage. As the patient becomes normotensive or coagulopathic, the area can rebleed when a tourniquet or suture is dislodged with movement. The same can happen with a vascular repair or vascular shunt. During transport, at least two tourniquets for each injured/operated extremity is judicious. The tourniquet can be preplaced on the injured extremity, to be tightened if there is the onset of exsanguinating hemorrhage.

Death

In the midst of the savagery of war, it is critical to maintain the tether to humanity. Care of the deceased is an important service, not only for the soldier’s family, but for the unit’s morale and well-being. Although the care of remains is under the direction of the Quartermaster Corps, it is usual that no matter where the death occurs, the unit will bring the body to the medical personnel in the area. The body is cooled if at all possible. As in any medical examiner’s case in the United States, all medical procedure items are placed in the body bag with the deceased. Clothing and operational gear are transported with the remains. Any records of the incident are preserved and sent with the remains. A full autopsy is completed by the military to determine the cause of death and enter the data into the trauma registry. In response to the loss, the unit holds a memorial service, where the deceased soldier is represented by the Fallen Soldier Battle Cross. The cross consists of the soldier’s rifle with bayonet attached and stuck into the ground; the helmet is placed on top, accompanied by dog tags that hang from the rifle with the boots of the fallen soldier in front of it (Figure 26-12). Its purpose is to show honor and respect for the fallen at the battle site. The ceremony for the lost comrade is formal and used as a ritualized means to collectively acknowledge the commitment and sacrifice of the soldier and to mourn his or her loss. Commanders are cognizant of the distress brought by the death of a unit member, especially if the unit has suffered multiple losses. Commanders use this ceremony to reaffirm with unit members the sense of unity, cohesion, and commitment to each other as they pursue their shared sense of mission.

FIGURE 26-12 Example of the Fallen Soldier Battle Cross and the memorial service.

Veterinary Issues

Dogs in conflict areas are ubiquitous. Despite education and warnings, soldiers often voluntarily interact with local dogs. U.S. military working dogs are vaccinated against rabies; the likelihood of rabies in local animals may be considerable. Dog bite treatment is similar to that in any emergency department, except that the ability to catch and monitor the animal is decreased, so watchful waiting to determine vaccination status of an animal is not an acceptable approach. Therefore postexposure rabies immunization is started.¹⁰

The lessons learned have been consideration of preexposure rabies vaccination for personnel with high exposure to local dogs; this requires that adequate supplies of rabies vaccine are reasonably available. It is better to have the rabies vaccine on hand than have to transfer the service member to another location for treatment; this is especially true if the environment is not secure.

Working dogs may be seen as patients in emergency treatment areas of the hospital, especially if a veterinarian is not immediately available. Care of working dogs is described in First to Cut: Trauma Lessons Learned in the Combat Zone.¹⁰ Basic damage control principles are used for resuscitation and surgery.

Unexploded Ordnance*

Unexploded ordnance (UXO) may include aerial bombs, rockets, artillery and mortar shells, grenades, and mines. Any location where a war has been fought within the past century has potential for retaining these items. Crews excavating streets in urban areas of England, France, and Germany often uncover UXO from World War I or World War II. Many areas of the United States that have been used for bombing or artillery ranges are adjacent to wilderness regions. Although they are usually well marked as impact areas, they still may pose a risk for the unwary traveler. Many areas of the shallow ocean accessible to scuba divers contain sunken munitions transports and warships that contain massive amounts of unexploded bombs, shells, and torpedoes. Another problem that has arisen is the use of mines and booby traps to protect marijuana and opium fields and illegal drug laboratories.

Currently, unexploded land mines represent a significant health problem in Southeast Asia, the Balkans, Central America, Egypt, Iran, and Afghanistan. The International Red Cross estimates that someone is killed or injured by a land mine every 22 minutes. The average number of mines deployed per square mile in Bosnia is 152; in Iran, 142; in Croatia, 92; and in Egypt, 59. There are a total of 23 million mines in Egypt alone.¹⁰

Land mines may be commercially manufactured or produced locally from available materials (Figure 26-13). Commercial land mines currently produced in the United States have a limited active life and self-destruct after their active life has expired. Unfortunately, this is not true of older types of mines or mines produced by other countries. Locally produced mines have no standard size, shape, or detonation pattern and may be very difficult to detect and defuse. These types of land mines are used extensively in El Salvador, Malaysia, and Guatemala.

FIGURE 26-13 An example of an antipersonnel mine manufactured by the Soviet Union.

Land mines have two primary functions, the first of which is to cause casualties—the so-called antipersonnel mines. These may be blast or fragmentation type. Fragments may be accelerated at 4,500 ft/sec (3068 mph), or double the speed of a high-velocity rifle. The fragmentation type may be either directional or nondirectional (Figure 26-14). Antipersonnel mines may cause lethal or nonlethal injuries in several persons. Wounded soldiers require more care than do killed soldiers, and the tactical effect may be the same. The second primary function is to destroy vehicles, such as tanks, so mines intended for this purpose are usually much larger.

FIGURE 26-14 A, An improvised mine, or booby trap, manufactured from a hand grenade and materials at hand. B, A directional type of mine used against unarmored vehicles or personnel.

All mines have three basic components: (1) triggering device, (2) detonator, and (3) main explosive charge. The triggering device differs depending on the type of mine. Blast mines usually involve a pressure type of trigger and occasionally are command detonated, especially for antitank purposes. Many antitank mines will not explode unless a pressure of 136 to 181 kg (300 to 400 lb) is applied. The M14 blast antipersonnel mine needs only 9 to 14 kg (20 to 30 lb) of pressure to trigger detonation. Fragmentation mines are usually triggered by trip wires or similar “touch” devices. The M18A1 fragmentation mine, or claymore mine, can also be command detonated by an electronic trigger.

Booby traps other than land mines may be mechanical, chemical, or explosive. During the Vietnam War, venomous snakes were used, as well as the notorious sharpened bamboo spikes known as punji or tiger traps.

The distribution of mines usually entails spreading them on the surface of the ground; by air along roads, railways, and defensive positions; or hiding them by burying or camouflage along trails or suspected routes of approach. The energy transmitted from blasts may cause extensive damage. When a detonation occurs, a solid or liquid is converted into a gas under pressure with extreme energy release. Detonation of a high-speed chemical reaction also causes high temperatures and pressures. Factors influencing the blast wave are the Mach stem, reflection, absorption, flow of the pressure wave, and the medium in which the blast occurs (e.g., air, water, soil). Injuries from land mines depend on several factors: type of mine (blast versus fragmentation), position on the ground, method of detonation, whether it explodes above the ground, position of the victim, environment, and type of soil.

Four general patterns of injuries occur with land mines. Pattern A injuries occur with small blast mines, such as the U.S. M14 and the Chinese Type 72. These injuries usually involve only the leg below the knee. Complete or partial foot amputations are most common, and trunk or head injuries are rare. Pattern B injuries are caused by larger blast mines, such as the Russian PMN. These mines contain four to six times as much high-explosive material, and the cone of explosion is much larger. The injuries seen with this type of land mine usually involve massive soft tissue injuries to both legs below and above the knee and also commonly the pelvis, abdomen, and chest. Pattern C injuries are generally caused by Russian PFM-1, or “butterfly,” mines. These mines are usually distributed by air, and the wings are designed to help spread the mines. They are triggered by pressure applied to the wings; handling the mine commonly does this. Most of the injuries involve amputation of the hand at the wrist; often the head, neck, and chest are also injured. Unfortunately, loss of one or both eyes is not uncommon with this mine. Pattern D injuries are caused by fragmentation mines. These may be bounding mines, such as the U.S. M16 or the Russian OZM, or directional mines, such as the U.S. M18A1 or the Russian MON. They are designed to spread metallic fragments over a wide area at the height of a person’s waist. The fragments lose their energy much faster than a bullet projectile but at close range can be devastating. The lethal range is usually 25 to 50 m (82 to 164 feet), with casualties occurring out to 200 m (656 feet). The injuries are quite similar to gunshot wounds and are often multiple.

Large, unexploded artillery shells or bombs may cause a combination of blast and fragment injuries but on a larger scale, sometimes involving scores of victims. Many military and civilian casualties are caused by IEDs, which may be conventional explosives; improvised from fertilizer, propane, or other unconventional explosives; artillery, mortar, or other ordnance; or explosive charges removed from such ordnance. IEDs are commonly used by terrorist groups, which may detonate the devices either by timing mechanisms or by command, sometimes in suicidal attacks. These devices are usually detonated in crowded areas or near important political or military targets to create the greatest impact. Examples are attacks on Oklahoma City’s Alfred P. Murrah Federal Building, the Beirut Marine barracks, and multiple incidents in Iraq.

Injuries from explosives can include any combination of blunt, penetrating, burn, or blast wave/pressure injury. Injury patterns are usually worse with closer proximity. These injuries can also involve cavitation, crush, embolism, fractures, lacerations, and perforations of organs. The primary blast injury is due to the pressure wave and the direct effects of the pressure pulses, both overpressure and negative pressures. Significant blast winds can be produced because of the detonation. Injury is most often associated with the gas-filled organs, middle ear, lungs, and intestines. Lung injuries cause the greatest morbidity and mortality. Rapid acceleration of shrapnel to 50 ft/sec (34.1 mph) lacerates tissue, and at 400 ft/sec (272.7 mph) shrapnel is able to penetrate body cavities. Because the wounds are deceptive, the need for amputation may first be recognized later. Tetanus prophylaxis must be rendered. The tertiary injuries involve the victim being accelerated by the blast and thereby impacting other objects when thrown any distance. The median lethal dose (LD₅₀) of being thrown is about 26 ft/sec (17.7 mph), and the limit of human tolerance is about 10 ft/sec (6.8 mph). The other injuries that commonly may occur are burns, crush (from building collapse), and chemical exposures. A very important aspect of the care for any patient with an explosive munition mechanism of injury is the possible lack of any initial overt manifestation of injury. There must be a high index of suspicion because many victims will not manifest for several hours. The first sign of respiratory failure is usually increased respiratory rate. Acute respiratory distress syndrome may not manifest for 24 hours. Treatment of these injuries can be very complex and involves vascular, orthopedic, soft tissue, abdominal, and craniofacial procedures. In most of these injuries, massive debridement is necessary. Rarely, UXO may be embedded in soft tissues and body cavities and must be removed in the operating room, possibly endangering the lives of medical personnel. Initial treatment involves airway control, treating tension pneumothorax, and controlling hemorrhage. Tourniquets are often necessary to control the bleeding from amputated limbs. Splinting the injured extremity and covering the wound to prevent further contamination is necessary. Initial debridement must be done carefully; removal of fragments may cause bleeding to recur. Penetrating injuries of the pelvis and abdomen usually require laparotomy, and soft tissue injuries may require multiple reconstructive procedures. The wounds are usually highly contaminated with soil, clothing, and fragments that may be driven deeply into tissue proximal to the obvious injuries.³⁹ Broad-spectrum antibiotics and tetanus prophylaxis are appropriate in all cases, and fluid resuscitation is usually indicated with extremity injuries. Postsurgical infection of mine injuries is common and greatly increases morbidity and mortality. Most victims who survive never completely regain normal function, especially if the initial treatment was delayed or inadequate.

Air-filled organs are most susceptible to damage. The tympanic membrane can rupture at a pressure of approximately 150 kPA (kilopascal) or 5 to 7 psi over atmospheric pressure. Blast injuries without fragmentation may cause tympanic membrane rupture, blast lung resulting from alveolar rupture, and intestinal rupture, although the latter is more common with underwater mine explosions. Pulmonary blast injury may manifest as contusions and hemoptysis. The victim may have subcutaneous emphysema, respiratory distress, and tachypnea. Arterial air embolism may occur with cardiac and neurologic manifestations. The mechanism is production of an overpressure wave that travels through tissue of various densities and causes tearing injuries at membrane interfaces. These injuries must be suspected in any victim involved in a blast, whether from a land mine or other explosive device. Solid organs, although more protected from overpressure, are very susceptible to missiles. Neurologic and head injuries are commonly associated with blast injury. Blast winds can cause extremity injury as severe as traumatic amputation.

Scuba divers and swimmers who are involved in underwater explosions may have more serious injuries because of the increased speed of sound in a liquid medium. This can cause more severe tearing of membranes at the fluid–air interface and additional trauma secondary to a “water hammer” effect and spalling. The position of the victim and the number of shock waves caused by reflection of the blast wave off walls and ground may increase the amount of damage. Victims in contact with solid objects, such as the hull of a ship or vehicle, may have increased injuries because of increased velocity of the blast wave through solids. Burns and translational injuries, whereby the victim is thrown by the blast and has injuries similar to a fall or motor vehicle crash, also occur.

Traumatic brain injury (TBI) is common in blast injuries and is referred to as the “hallmark injury” of the current Iraqi and Afghani conflicts. Symptoms can range from coma to mild cognitive dysfunction, depression, and behavioral changes. PTSD is often associated with TBI.

Generally speaking, the closer the victim is to the blast, the greater the injury. The tympanic membrane will rupture at overpressures of 5 to 7 psi. This causes acute hearing loss, pain, and tinnitus. Blast lung is caused by the overpressure wave passing through the chest wall and may involve one or both lungs. Chest pain, dyspnea, and hemoptysis may manifest immediately or be delayed up to 48 hours. Chest radiograph may show patchy or diffuse infiltrates, pneumothorax, subcutaneous air, and hemothorax. Implosion of air into the vascular system may cause air embolism and sudden death. Abdominal injuries in air blast are uncommon, but in water blast may manifest as abdominal pain, nausea, vomiting, and tenesmus. Sigmoid and transverse colon injuries are most often seen, followed by small bowel and solid organ (such as liver and spleen) injuries from the water hammer effect. Abdominal injuries may have a delayed (up to several days) presentation. The key to therapy is to be suspicious of occult injuries in any victim of a blast, whatever the cause. Most injuries will manifest within the first hour; however, because injuries may be delayed in presentation, observation and close follow-up are critical. Treatment is generally supportive for ear and lung injuries and operative for abdominal injuries.*

Traumatic Emotional Stress in Austere Environments: The Continuum of Effects

Traumatic emotional stress is a common and serious problem that is especially relevant to the field of austere medicine. The military has found that all military members, including enlisted soldiers and officers, can benefit from an overview of the causes and signs and symptoms that define the continuum of traumatic stress. This section reviews basic precepts, describes the general concept of traumatic stress, and cites some of the management strategies that have demonstrated their utility in the field.

If the patient is armed, a safety issue that needs to be addressed is disarming the patient and ensuring safety of the team and the injured individual. Frederick M. Burkle, MD, stated,

This certainly pertains to military personnel in areas of armed conflict and also holds true for other responders and aid workers.

Mild Traumatic Brain Injury

Mild traumatic brain injury (MTBI) is commonly known as concussion; it is rarely life threatening (Figure 26-15). Gioia and Collins stated the following:

FIGURE 26-15 2000-2010: Traumatic brain injury categories.

(From Defense and Veterans Brain Injury Center: Military Acute Concussion Evaluation. http://www.pdhealth.mil/downloads/MACE.pdf.)

Further, the American Congress of Rehabilitation Medicine⁵² characterizes MTBI as “a traumatically induced physiologic disruption of brain function which involves at least one of the following: 1) any period of loss of consciousness; 2) any loss of memory for events immediately before or after the accident; 3) any alteration in mental state at the time of accident (e.g. feeling dazed, disoriented, or confused); 4) focal neurologic deficit(s) that may or may not be transient.”

Specific causes of MTBI commonly include a blow to the head or violent shaking often caused by motor vehicle accidents, falls, and sports injury; among military personnel, the most common source is overpressure wave blast caused by explosion. Although not life threatening, the symptoms of MTBI can be serious and a meaningful threat to quality of life.