Chapter 21 Wilderness Trauma and Surgical Emergencies*

Kirby R. Gross, Bryan R. Collier, William P. Riordan, Jr., John A. Morris, Jr.

Purpose

This chapter is written to provide physicians and health care practitioners with a concise, pragmatic approach to the management of trauma and surgical emergencies encountered in a wilderness environment. Our focus is directed primarily at the health care professionals responsible for the well-being of expedition members.

Wilderness expedition health care providers will have varied capabilities and experience, but it is the environment (location, time from medical facilities, and conditions) and available resources that will most influence patient outcome. Complex interventions in the field are frequently impractical. With ongoing debate concerning issues ranging from the value of field resuscitation for internal hemorrhage to the method (if any) of closure of animal bite wounds, it remains clear that simple things, such as identifying injuries, establishing an airway, keeping the patient warm, and making expedient evacuation plans, most strongly influence survival.^21,^26,⁷⁴

The key to successful management of wilderness emergencies is preparedness. Knowledge of the Advanced Trauma Life Support (ATLS) protocols provides a scaffold for preparation for wilderness travel. The simple, concise principles contained in ATLS concepts are well suited to management of wilderness emergencies, where resources are scant and prompt response is essential to victim survival. Newer training programs, such as Advanced Wilderness Life Support (AWLS), provide additional wilderness-specific learning opportunities.

In addition to knowledge and skill, physicians in the wilderness environment should prepare by understanding their role in the expedition. Lessons from teamwork management have application to the wilderness environment as well as the sophisticated medical environment. The basic tenets of teamwork are those of (1) team structure, (2) application of problem-solving strategies, (3) communication, (4) execution, and (5) improving team skills.⁷⁹

The provider in an expedition should fully understand his or her role during preparation. Is the physician a team member because he or she has medical training and expertise that has application to the specific environment and potential risks? Is the provider serving in a capacity in which he or she has been directed to become the responsible physician if needed? Or, is the provider in the wilderness to escape from professional responsibilities and enjoy an avocation that can only be appreciated in the austere environment?

The medical director of an expedition takes on a significant responsibility in preparation for the trip. He or she must provide input to the expedition leader regarding local health threats and also assess risk. Screening participants for durability and comorbidities is important. The medical director must be knowledgeable in wilderness medicine protocols. For longer expeditions, diagnostic capability such as handheld ultrasound and point-of-care testing should be considered. Also, establishing contact with evacuation assets before commencing the trip is prudent. The medical director must have a plan for transfer of information to the next level of care. It may be as simple as recording findings on a piece of tape applied to an uninjured location on the casualty. Paper is a poor way to transfer information. In the evacuation process, paper will often be lost because of helicopter rotor wash and jostling during travel. Standard time designations should be used. The casualty may be evacuated across different time zones. Any times recorded for findings or interventions should have the appropriate time zone clearly designated.

In any austere environment, physicians will commonly and immediately be thrust into a position of authority. The time to clarify structure and roles is before the expedition. Understanding the expectations for each provider permits appropriate team preparation. The physician in a position of responsibility would be wise to brief team members about contingencies before entering the austere environment. The specifics of wilderness preparation, equipment, and medical supplies are presented in Chapter 91.

Wilderness Trauma Emergencies

Overview

All three classic mechanisms of trauma (penetrating, blunt, and thermal) may be seen in the wilderness. Particularly in the austere environment, blunt trauma presents pitfalls, because the patient is at risk due to blunt mechanisms. Delayed diagnoses in victims of blunt trauma occur in highly sophisticated medical environments. The possibility of delayed diagnoses in the wilderness is even greater due to lack of diagnostic resources.

The medical literature is limited regarding the incidence of injury incurred during wilderness-related activities. It is estimated that greater than 10 million Americans participate in wilderness backpacking and camping activities annually. A study by Gentile and colleagues ³³ documented the injury and evacuation patterns recorded by the National Outdoor Leadership School over a 5-year period. Injuries occurred at a rate of 2.3 per 1000 person-days of exposure, with orthopedic and soft tissue injuries most frequent. Montalvo⁶⁵ analyzed case incident report files from eight California National Park Service parks and found an injury incidence of 9.2 nonfatal events per 100,000 visits, with 78 fatalities reported in a 3-year period. In a prospective surveillance study evaluating 38,940 days of wilderness exposure on the Appalachian Trail,¹² foot blisters and diarrhea were the most common reasons that hikes were prematurely ended. Leemon and Schimelpfenig⁵² showed that over 50% of evacuated participants in the National Outdoor Leadership School were able to return and finish their courses. These studies document a low risk for injury but highlight the possible morbidity resulting from wilderness injury or illness and the need for rapid, uniform intervention.

A 2001 study from the University of Arizona ³⁶ highlighted wilderness mortalities over the past 13 years. Alcohol was the most common causative factor, involved in 40% of the 59 unintentional trauma deaths. In addition, 80% of these victims died immediately or before evacuation could be completed. This again emphasizes the importance of sound judgment and preparedness as keys to maximizing care to rescuers and expedition members.

Establishing Priorities

There are three immediate priorities in managing wilderness trauma:

1 Control oneself. It is normal to feel anxious when confronted with an injured victim. However, anxiety must not be transmitted to the victim or other members of the expedition team. One must be in control of oneself to take control of the situation.

2 Control the situation. The first priority in controlling the situation is ensuring the safety of uninjured members of the party. Expeditious evacuation of a victim requires that all expedition members function at maximal efficiency; even minor injuries to other members in the group can jeopardize physical strength, functional manpower, and success of the evacuation. Although the physician member of the team may not be the expedition leader, his or her position is automatically elevated during a medical crisis. However, this does not mean that the physician should dominate the evacuation process. Although the expedition leader must rely on the medical assessment provided by the physician, the leader is best prepared to plan the evacuation.

3 Obtain an overview of the situation. The victim’s general condition should be evaluated. Is the victim in immediate distress from a condition that requires relatively simple management, such as airway control? Is the victim in such a precarious environmental situation that he or she needs to be moved before resuscitation? Scene security may be integral to the safety of the injured and caregiver. Is the victim properly protected from the elements, including sun, wind, cold, and water? Hypothermia remains one of the most important contributors to trauma-related coagulopathies.⁹¹

In addition to these three priorities, McSwain and Kerstein ⁶² have described the “golden principles” of prehospital trauma care. Although not intended for wilderness medicine, several key components are applicable: ensure scene and provider safety, use primary and secondary surveys, provide cervical spine immobilization, control external hemorrhage, keep the patient warm and use warm intravenous (IV) fluid resuscitation if possible, initiate early transport, and, above all, do no further harm.

After the victim has been placed in the most stable and safe environment, the examining physician is ready to implement the ATLS-based five steps of wilderness trauma management:³

5 Packaging and transfer preparation

The purpose of the primary survey is to identify and begin initial management of life-threatening conditions by assessing the following (called the ABCDE’s of trauma care):

• Airway maintenance and cervical spine stabilization

• Breathing

• Circulation, with control of significant external hemorrhage

• Disability: neurologic status

• Exposure/environmental control: completely undress the victim with careful attention to prevention of hypothermia

After the primary survey is performed, resuscitation efforts are initiated. The level of resuscitation depends on the equipment and expertise available (see Chapters 23, 91, and 94). At a minimum, resuscitation consists of control of external hemorrhage and, when available, administration of oxygen and provision of warm IV fluids.

The third step is the secondary survey, a head-to-toe evaluation of the trauma victim that uses inspection, percussion, and palpation techniques to evaluate each of the body’s five regions: head and face, thorax, abdomen, skeleton, and skin. A history should be taken at the same time as performance of the secondary survey. The specifics of the mechanism of injury, if unknown to the physician or caregiver, may be of vital importance. Loss of consciousness, head injury, the height of a fall, or the species of attacking animal may influence treatment and evacuation plans, as well as contribute to stability of the scene. The ATLS AMPLE method of rapid history taking is discussed later in detail in the Secondary Survey section. After this survey, the examining physician should formulate a definitive plan. It is useful to document all observations if circumstances permit. Such data may prove of critical importance to field evacuation or hospital personnel.

The first step in formulating a plan is to compile a list of the injuries. The next step is to determine if any injury warrants evacuation. A determination needs to be made as to the route of evacuation: air, land, or water. Aeromedical evacuation is expensive and, depending on the environment, may pose its own risk to both the victim and medical evacuation team. Aeromedical evacuation should be considered only for victims with potentially life- or limb-threatening injuries where the terrain and environment allow safe access, for the purpose of evacuation, to the patient.

Packaging the victim for evacuation is the final step. The evacuation effort requires organization, coordination, and great effort on the part of the expedition team. Transfer protocols are discussed within the respective injury sections.

Preparation for wilderness patient care should address the challenges associated with varying levels of personnel help, minimal medical resources, prolonged prehospital care, and difficult evacuation proceedings. However, with ATLS knowledge, improvisation, and an organized effort, the patient’s outcome can be maximized.

Universal (Body Fluids) Precautions in the Wilderness

A number of life-threatening viruses are transmitted through contact with bodily fluids. The Centers for Disease Control and Prevention (CDC) have established a set of standard precautions to be applied in all cases of contact with human body fluids:

• Goggles

• Gloves

• Fluid-impervious gowns

• Shoe covers and fluid-impervious leggings

• Mask

• Head covering

Created in 1983 and revised in 1987, recommendations for universal precautions and use of the aforementioned equipment have undergone no additional changes over the past decade. Multiple types of body fluids (blood, semen, vaginal secretions, cerebrospinal, pleural, synovial, pericardial, peritoneal, and pericardial) can place a caregiver at risk. In the wilderness setting, the materials necessary for universal precautions are rarely available. However, every victim in the wilderness must be assumed to carry a communicable disease. Every effort should be made to approximate universal precautions, particularly covering the hands and eyes.

Primary Survey

Persons injured in the wilderness should be assessed and their treatment priorities established based on their mechanism of injury, vital signs, and specific injuries. The victim’s vital signs must be assessed quickly and efficiently, with restoration of life-preserving vital functions.

Airway

The upper airway should be assessed for patency (see Chapter 20). This rapid assessment should include inspection for signs of airway obstruction, including foreign bodies and signs of facial or tracheal fractures that sometimes lead to airway obstruction. The chin lift or jaw thrust may be helpful in establishing an airway. If the victim can speak, the airway is likely not jeopardized, but this is not an absolute rule. Frequent repeated evaluation of the patient’s airway, breathing and circulatory status in the familiar ABC format is mandatory. In addition, a Glasgow Coma Scale (GCS) score of 8 or less indicates the possibility of a precarious airway and requires establishment of a definitive airway.

Specific attention should be directed toward the possibility of cervical spine injury. The victim’s head or neck should never be hyperextended, hyperflexed, or rotated to establish or maintain an airway. Approximately 10% of victims with head injuries or facial fractures have a concomitant cervical spine fracture. In one series of patients, 25% (29 of 116 patients) had unstable cervical fractures as defined by needing a halo or surgical intervention.²³ Such a fracture should be assumed to exist in any person with a significant injury above the level of the clavicle. If a situation requires removal of immobilizing devices, in-line stabilization, not traction, must be maintained.

Breathing and Ventilation

The victim’s chest should be exposed and chest wall movement observed. Because oxygenation and carbon dioxide elimination require adequate function of the diaphragm, chest and abdominal musculature, and ribs, any trauma sustained by these structures will alter normal pulmonary mechanics and increase the work of breathing. Establishment of an airway in the primary survey, although critical to patient survival, does not ensure adequate oxygenation or ventilation. All trauma victims must be continuously monitored for the signs and symptoms of hypoxemia and hypercarbia.

Auscultation, observation, and palpation of the chest after establishment of the airway are integral parts of the primary survey. Absent breath sounds may indicate improper placement of an endotracheal tube. This can occur with inadvertent esophageal intubation or intubation of a single lung (right or left mainstem bronchial intubation). Diminished breath sounds or asymmetric chest wall movement can occur with pneumothorax (simple or tension), hemothorax, or tracheobronchial obstruction. Observation and palpation of the chest may identify thoracic injuries such as rib fractures, fractures with flail segments, or pneumothorax (by the presence of subcutaneous emphysema).

Circulation

Evaluation of circulation is divided into assessment of cardiac output and control of major external hemorrhage. Manometric blood pressure measurement is not easily performed in the field, although it may provide useful data. Important information regarding perfusion and oxygenation can be obtained rapidly by determining the victim’s level of consciousness, assessing peripheral and central pulses, looking at skin color, and evaluating capillary refill time.

The pulse should be assessed first. Although the following are only general estimates and carry some inaccuracy, approximations of systolic blood pressure can be used if a palpable pulse is present:

• Radial artery—80 mm Hg

• Femoral artery—70 mm Hg

• Carotid artery—60 mm Hg

When circulating blood volume is reduced, cerebral perfusion pressure may be critically impaired, resulting in altered level of consciousness. Do not assume that altered level of consciousness is attributable to head injury. Altered levels of consciousness may be due to hypoperfusion of the brain.

Peripheral perfusion can be assessed using skin color and capillary refill. Pressure applied to the thumbnail or hypothenar eminence causes underlying tissue to blanch. In a normovolemic person, color returns to the nail bed within 2 seconds. In a hypovolemic, poorly oxygenated person, capillary refill requires more than 2 seconds. There is no direct relation between blood pressure and capillary refill. Capillary refill reflects flow, which is more important than blood pressure.

If hypovolemia is suspected on the basis of either absent pulses or prolonged capillary refill, the examiner should immediately assess the neck veins. Distended neck veins, although a nonspecific sign, may suggest tension pneumothorax or pericardial tamponade in the context of hypotension. Flat neck veins suggest hypovolemia and hemorrhagic shock.

Major hemorrhage can occur in five anatomic areas:

5 External environment

Exsanguinating external hemorrhage should be identified and controlled during the primary survey. Blood loss should be controlled by direct pressure on the wound. Tourniquets should not be used to control external bleeding unless direct pressure fails to control the bleeding. Tourniquets may be considered in the situation where pressure cannot be applied as the patient is being transported. In this situation, a tourniquet may be applied temporarily. As soon as the operational situation permits, the tourniquet may be removed and direct pressure reapplied. The greatest challenge for extremity vascular injuries is hemorrhage, not ischemia. Recent military experience has demonstrated that tourniquets may be used with infrequent untoward consequences.⁵⁰ Proper stabilization of long bone fractures (femur fractures specifically) minimizes blood loss into soft tissues. In the wilderness, little can be done about significant intrathoracic or intra-abdominal hemorrhage. In a modern trauma center, however, less than 5% of blunt trauma patients with intra-abdominal or intrathoracic injuries require surgery to control bleeding. Consequently, even significant blunt injuries in the wilderness carry a real probability for survival if basic ATLS principles are followed.

Rarely, large degloving injuries may be a source of significant blood loss. Hemostatic dressings have been developed to promote hemorrhage control in this type of wound. The hemostatic dressings require the benefit of pressure to be maximally effective. Several commercial products are available that promote clotting by different active agents. The hemostatic dressings are described in detail in Chapter 22.

Disability and Neurologic Assessment

The neurologic assessment of the injury victim conducted during the primary survey should be rapid and efficient. The victim’s level of consciousness should be established. In addition, pupillary size and reactivity should be assessed. Level of consciousness should be assessed using the GCS (Box 21-1). It is critical that the neurologic assessment be repeated hourly, particularly if evacuation is delayed. Deterioration in mental status portends a poor prognosis, although a variety of conditions other than intracranial injury can affect mental status. Hypoxia, hypovolemia, and hypothermia should be expeditiously corrected.

Exposure and Environmental Control

The victim should be fully undressed and exposed, if possible in a protected environment. Garments and gear should be removed if necessary by cutting them away, unless the garments can be dried and are essential for future protection from the environment. Wet clothing must be removed early to prevent hypothermia. It is mandatory to visualize the entire victim to document and assess injury. However, this step of the primary survey should be performed with caution. First, it is imperative to cover the victim immediately after removal of clothing. Hypothermia and its effects on mental status, cardiovascular function, and coagulation are among the most underappreciated entities in care of the trauma victim. The possibility of hypothermia should be entertained in all environments because it is most prevalent in the winter and summer months. Hypothermia reflects the inability of trauma victims to use available stored energy to carry on normal metabolic processes. A severely injured patient may become hypothermic in any ambient environment. Second, clothing and gear should not be removed from the victim unless complete immobilization of injuries can be achieved. Assessment of an area of injury should be performed, but clothing should be left to cover the patient to ensure body temperature is maintained. Expedition members may be wearing a variety of gear and clothing, including biking, skiing, or climbing helmets. Helmets should be removed with in-line stabilization of the cervical spine.

Shock

The shock state has been defined in many ways. Essentially, shock describes the physiologic condition in which oxygen delivery to the tissues of the body is not adequate for the metabolic demands of those tissues. This results in cellular hypoxia, anaerobic metabolism, and, eventually, cell death. Shock was defined historically by John Collins Warren as “a momentary pause in the act of death.” Nowhere is this adage more applicable than in the wilderness setting. Any physician who cares for trauma victims has witnessed an apparently “stable” victim rapidly deteriorate and die. With only clinical acumen, the wilderness physician must be sufficiently astute to identify the subtle early signs of shock.

The treatment for shock is resuscitation, which may be defined as any intervention that restores blood flow and cellular oxygenation. The power of the primary survey lies in the fact that it is essentially a form of resuscitation. Rapid identification and treatment of conditions leading to hypoperfusion facilitate their reversal. A key in resuscitation of the trauma victim is identification of and stopping ongoing hemorrhage.³ Rapid control of external hemorrhage is critical. External sources of hemorrhage can initially be managed with direct pressure. If direct pressure must be interrupted during extrication, other techniques may be used. Exsanguinating hemorrhage from the scalp can be managed with sutures. Tourniquets may be applied to extremities for temporary control.⁵⁰ Although the majority of trauma victims exhibiting signs of shock in the wilderness have sustained acute blood loss, a nonhemorrhagic entity, such as a spinal cord injury or pneumothorax, may be responsible for shock.

Hemorrhagic shock is classified according to the blood volume that has been lost. A central question in caring for victims of blood loss in the wilderness is the reliability of vital signs in quantifying degree of hemorrhage. Associated with each class of hemorrhage are clinical signs that allow a caregiver to quantify blood loss (Table 21-1). It is evident that assessing blood pressure alone is a poor way to predict impending deterioration. When hypotension is present, a normal individual has already lost 30% of his or her blood volume, and salvage may be impossible. Resuscitation should be initiated at the first sign of shock, equating to class II hemorrhage, and evacuation planned accordingly.

TABLE 21-1 Classes of Hemorrhagic Shock

Vascular Access

Vascular access must be obtained promptly. The standard method of obtaining access is by insertion of two large-bore (16-gauge or larger) catheters, preferably into peripheral veins of the upper extremity. Alternatives include using lower extremity veins and obtaining central venous access. If peripheral access cannot be secured, the femoral vein should be the next site attempted. Advantages of femoral vein access include ease of cannulation relative to jugular and subclavian access, and fewer complications.⁹³

Depending on expertise, the internal jugular and subclavian veins may be accessed. Despite a higher incidence of complications compared with peripheral access, central access complication rates in trauma centers have been demonstrated to be less than 5% in most studies.⁹³ If peripheral access is inadequate or unobtainable, it is clear that the next site attempted should be determined by the provider’s level of confidence and expertise. As a last resort, venous cutdown may be considered. Despite fewer complications than central access, cutdowns are experience and equipment dependent and not recommended in the wilderness environment.

Intraosseous access is also to be considered in adults. Several commercially available products are available (Figure 21-1). The manubrium is the target for insertion of the FAST1 intraosseous device. The Bone Injection Gun (BIG) and EZ-IO can be used to access the bone in the proximal tibia and humerus. The FAST1 and BIG are impact-driven devices. The EZ-IO is a drill-based device. Skills to successfully place intraosseous venous access can be acquired with short training times.³⁰

FIGURE 21-1 A, FAST1 intraosseous infusion system. B, Bone Injection Gun (BIG). C, EZ-IO.

Children in the wilderness younger than 6 years of age in whom venous access cannot be obtained should undergo intraosseous resuscitation. This is accomplished by introducing a needle through the periosteum of the tibia just inferior to the tibial tuberosity. Needles that are 18- to 20-gauge are preferable, but any needle strong enough to penetrate the periosteum without bending can be used.

Of the resuscitative therapies that potentially may be initiated in a well-prepared expedition, volume resuscitation deserves considerable attention. Fluid resuscitation in trauma has been a contentious topic, perhaps overly so, relative to fluid type and amounts used. A number of recent studies focusing on the prehospital administration of fluids in trauma victims not only rehashed the fluid composition debate but called into question the efficacy of prehospital resuscitation.⁷⁴ Although further prospective trials are needed relative to fluid type and prehospital use, an impressive compilation of data has been amassed looking at resuscitative fluids in the trauma victim. Past studies have not only compared colloids with crystalloids⁸⁹ but explored the use of blood and plasma substitutes and hypertonic saline. Detailed analyses of these studies is beyond the scope of this chapter, but a summary of fluid recommendations is in order.

In small volumes, hypertonic saline has been shown to be an effective resuscitative fluid, and its efficacy in closed head injury is under evaluation. Currently, no improvement in survival has been demonstrated using hypertonic saline compared with crystalloid, and its use has been associated with hypokalemia, pulmonary edema, and dramatic increases in serum sodium and osmolarity.⁶ The significance of these reported complications in trained hands is questionable, and hypertonic fluids may have a future role in resuscitation. Further study is warranted on the use of hypertonic saline, but its use in the wilderness setting is not recommended at this time.

Based on the current literature, it is clear that both colloids (including hetastarches and albumin) and crystalloids are efficient volume expanders.⁸⁰ Larger volumes of crystalloids than of colloids are needed to achieve similar resuscitative end points, usually in a ratio of 3 to 1. However, no benefit in survival by using colloids has been demonstrated, and recent studies indicate that their use in critically ill patients may increase mortality.^18,⁷¹ In addition, no proved detriment, including increased extravascular lung water, impaired wound healing, or decreased tissue oxygen diffusion, has been demonstrated with the use of large volumes of crystalloids. Crystalloids are safe, nonantigenic, easily stored and transported, effective, and inexpensive. Most experts in trauma care agree that crystalloid is preferable to colloid infusion in the prehospital, early resuscitative phase of trauma care. Accordingly, the resuscitative fluid recommended by ATLS protocol is normal saline.

In expeditions in which weight and space are considerations, colloids may have an advantage. “Colloid fluids will achieve a given increment in plasma volume with only one-quarter to one-third the volume required of crystalloid fluids.”⁵⁸ To restore circulating volume, colloids provide greater efficacy per weight/volume trekked into the austere environment. For the expeditionist carrying resuscitation fluids in a backpack, 1 lb of colloid will provide about three times the volume expansion of 1 lb of crystalloid.

Several animal studies and recent human clinical trials in trauma victims have found that treatment with IV fluids before control of hemorrhage resulted in increased mortality rates.^8,⁶⁰ Although these data are compelling, they have been accumulated in victims with penetrating injuries and short prehospital times, and the definition of prehospital resuscitation in these studies comprised widely varying volumes. Prehospital resuscitative protocols remain in evolution. However, application of these data to the wilderness setting at the current time is dangerous, for a number of reasons. First, the leading cause of death in wilderness trauma is head injury. Many multiple-trauma victims have a head injury, and it may be impossible to discern whether an intracranial lesion is present. Although under continued study, the current approach to management of head injury is aggressive maintenance of cerebral perfusion pressure to control intracranial pressure (ICP). Underresuscitation in the context of an intracranial injury could be catastrophic. Second, the multisystem-injured victim frequently presents with associated orthopedic injuries. A victim with closed extremity fractures with significant contained hemorrhage benefits from fluid resuscitation. Third, a victim with significant external hemorrhage that can be controlled before evacuation benefits from intravascular repletion.

In summary, resuscitation with IV fluids should be initiated in the field, particularly in victims with head injury and unquantified multiple trauma. Victims should have vascular access secured and resuscitative fluids given in the form of normal saline as dictated by severity of injuries and hemodynamics. In patients in whom urinary catheterization can be performed, a target of 30 mL/hr is a good target. In those patients in whom hourly urine output cannot be determined, other measures of perfusion, such as heart rate, blood pressure, and mental status, can determine the efficacy of resuscitation.

Secondary Survey

The secondary survey is an extension of the primary survey and should not be undertaken until the primary survey is complete and the victim has been stabilized. In addition, resuscitative regimens, if available, should have been initiated. The secondary survey is a head-to-toe assessment of the victim, including history and physical examination. The face, neck, chest, abdomen, pelvis, extremities, and skin should be examined in sequence. A more detailed neurologic examination should be completed, including reassessment of the GCS. The neck should be examined independently of the thoracolumbar spinal cord. Examination of the pelvis should not include the traditional “rocking” to determine stability, because in the presence of pelvic fractures, this action may exacerbate existing comminution.

The detailed secondary survey should not delay evacuation packaging. As in the nonwilderness setting, it is imperative to repeat the primary survey as the victim’s condition warrants. Specific examinations are discussed in the sections covering regional injuries.

Adjuncts

Resuscitation should be initiated simultaneously with the primary survey. The degree of resuscitation depends on available resources, experience of the rescuer(s), and environmental conditions. Under the best circumstances, initial management of the wilderness trauma victim provides for airway control, adequate oxygenation and ventilation, appropriate fluid resuscitation, and stabilization of cardiac function while continuing to monitor and reassess the patient’s vital signs. As adjuncts to the secondary survey, it also includes placement of a urinary catheter and nasogastric (NG) tube. This degree of resuscitation will be almost universally unavailable in the wilderness setting. Here, resuscitation may be limited to oral administration of warm, high-calorie fluids and maintenance of victim comfort and body temperature.

An NG tube and indwelling urinary (Foley) catheter should be placed if available and appropriate. Aspiration of gastric contents can be catastrophic in terms of patient survival after trauma. Gastric decompression with an NG tube may help prevent this type of adverse event in patients with a depressed level of consciousness. It should be remembered that children can exhibit significant hemodynamic consequences secondary to massive gastric distention. In this setting, decompression becomes critical. If possible, NG tubes should be placed in persons who are endotracheally intubated in the field. The tube can be aspirated sequentially with a syringe or left open to gravity drainage. Any suspicion of facial fracture should deter attempts to place an NG tube, and orogastric decompression should be chosen instead.

A Foley catheter can assist in volume assessment and hemodynamic status determination in a critically injured victim. Hourly urine output typically does not decrease until the onset of class III hemorrhagic shock, with loss of 30% to 40% of blood volume. Contraindications to urinary catheter placement in the field are blood at the urethral meatus, high-riding prostate, scrotal hematoma, and personnel not experienced in placement.

Injuries to the Head, Face, and Neck

The secondary survey begins with examination of the entire head and scalp for evidence of skull or facial fractures, ocular trauma, lacerations, and contusions. The scalp is thoroughly palpated for tenderness, depressions, and lacerations. The bones of the face, including the zygomatic arch, maxilla, and mandible, are palpated for fractures. Elements of the GCS are repeated.

The wilderness eye is discussed in detail in Chapter 28, but general examination principles are simple. Significant periorbital edema may preclude examination of the globe, so assessment should be carried out early. The globe should be evaluated for visual acuity, pupillary size, conjunctival hemorrhage, lens dislocation, and entrapment. Persons with significant facial trauma have a high incidence of associated ocular or orbital injuries.⁷⁷ Recent studies of ocular injuries in trauma victims have emphasized underappreciation by many disciplines of ocular and periocular signs indicative of significant underlying injury.⁷³

Head Injuries

Approximately 500,000 to 2 million cases of head injury occur in the United States yearly.³⁴ Of these, approximately 10% result in the patient’s prehospital death.³ Long-term disability associated with head injury is significant, with more than 100,000 persons suffering varying degrees of permanent impairment. Because of the high-risk nature of traumatic brain injury (TBI) and the impact of initial management on disability and survival, clinical management objectives must address both immediate survival and long-term outcome. Management guidelines for head injuries in a wilderness do not exist, and a wide range of clinical approaches are used in hospital settings.³⁴ However, the literature suggests that morbidity and mortality can be reduced by means of a protocol that includes early airway control with optimization of ventilation,⁴⁰ prompt cardiopulmonary resuscitation, and rapid evacuation to a trauma care facility.

Initial management of head injury in the wilderness should follow established ATLS protocols. Prompt attention must then be given to victim triage, evacuation strategies, and ongoing resuscitative needs to prevent or minimize secondary brain injury. Expeditious evacuation to a neurosurgery-capable trauma center is essential.

Multiple clinical and experimental studies have demonstrated the detrimental effects of hypoxia on the injured brain. A definitive airway should be established if any degree of neurologic or respiratory compromise exists. Cervical spine injuries are common in patients with TBI. Therefore cervical spine immobilization is paramount in the prevention of further devastating neurologic injury.

After immobilization, attention is directed to the prevention of secondary brain injury. The purpose of the wilderness head injury protocol is to allow individuals with widely varying levels of experience and expertise to identify signs of significant head injury, begin proper resuscitation in the context of prevention of secondary brain injury through airway maintenance and hemodynamic support, and evacuate appropriately.

Anatomy

The scalp comprises five layers of tissue that cover the calvaria: skin, connective tissue, galea aponeurotica, loose areolar tissue, and periosteum of the skull. The galea is a fibrous tissue layer with important ramifications in closure of scalp wounds, discussed later in this chapter. Loose areolar tissue beneath the galea represents the site of accumulation of blood in scalp hematomas. A rich vascular network located between the dermis and the galea supplies the scalp. When lacerated, these vessels can be a significant source of hemorrhage, which may be important if evacuation is impossible or delayed.

The skull is composed of two groups of bones that form the face and cranium. Cranial bones are divided into the calvaria and skull base. The calvaria is composed of frontal, ethmoid, sphenoid, parietal, and occipital bones. Within the skull, the brain is covered by three membranous layers that may be of pathophysiologic importance after injury. However, in the wilderness environment, these layers have little clinical relevance (except in terms of defining an open versus closed brain injury).

Pathophysiology of Traumatic Brain Injury

TBI can be divided into primary and secondary brain injuries. Primary injury consists of the physical or mechanical insult at the moment of impact, and the immediate and permanent damage to brain tissue. Little can be done in the wilderness setting relative to primary brain injury. Secondary brain injury is the biochemical and cellular response to the initial mechanical trauma and includes physiologic derangements that may exacerbate effects of the primary trauma. Such pathophysiologic alterations include hypoxia, hypotension, and hypothermia. Compounding these pathophysiologic alterations is elevation of ICP after TBI. Increased ICP increases cerebral ischemia and exacerbates secondary brain injury.

Many forms of head injury result in elevated ICP, the duration of which is significantly correlated with poor outcome. The Monro-Kellie doctrine states that the volume of intracranial contents must remain constant because the cranium is a rigid container. The normal compensatory response to increased intracranial volume is to decrease venous blood and cerebrospinal fluid (CSF) volume within the brain. If this normal response is overwhelmed, small increases in intracranial volume result in exponential increases in ICP. A rigid bony cranium cannot expand to accommodate increases in brain volume and the resultant increase in ICP. Brain parenchyma becomes compressed and eventually displaced from its anatomic location. In the most devastating circumstances, the brain parenchyma herniates toward the brainstem through the largest cranial opening (the foramen magnum) and death rapidly follows. The volume–pressure curve in Figure 21-2 relates the small, but critical, time period between neurologic symptoms, hemodynamic decompensation, and brainstem herniation. Elevation in ICP directly correlates with secondary brain injury. Therefore the field provider must attempt to minimize ICP of head-injured patients to the greatest extent possible.

FIGURE 21-2 Critical time period between decompensation and brainstem herniation after traumatic brain injury.

The most important priority in minimizing secondary brain injury in the field is optimizing cerebral perfusion pressure (CPP). CPP is related to ICP and mean arterial pressure (MAP) as follows:

A CPP less than 70 mm Hg after head injury correlates with increased morbidity and mortality.^3,³⁹ Cerebral blood flow (CBF) should be maintained at approximately 50 mL/100 g brain tissue per minute.⁵⁷ At 5 mL/100 g per minute, irreversible damage and potential cell death occur.³ Study data have shown a correlation between low CBF and poor outcome.⁵⁷ At a MAP between 50 and 160 mm Hg, cerebral autoregulation maintains CBF at relatively constant levels. Not only is autoregulation disturbed in injured regions of the brain, but a precipitous fall in MAP can further impair autoregulatory function, decreasing CBF and exacerbating ischemia-induced secondary injury. The field provider is able to combat a rise in ICP by simply optimizing MAP through aggressive IV fluid resuscitation.

Diagnosis

The three useful descriptions of head injury that may be applied to field recognition are history, severity, and morphology. History includes mechanism of injury, timing of the event, and related circumstances. This knowledge assists in the decision-making process with regard to resuscitation and evacuation.³ Mechanism of injury is identified as blunt or penetrating trauma. The anatomic demarcation between blunt and penetrating injury is traditionally defined by violation of the outer covering of the brain (dura mater). Blunt injuries in the wilderness setting most often result from falls, falling objects, or assaults. Penetrating injuries are most commonly gunshot or other projectile wounds. Severity of injury can be estimated by quantifying the GCS and pupillary response. The generally accepted definition of coma is a GCS score less than or equal to 8; these patients often require endotracheal intubation. Although GCS score does not directly correlate with the need for intubation, it is essential that all head-injured patients be provided a stable, secure airway by the most appropriate means available. It is important to note the TBI victim’s best initial motor response because this is most predictive of long-term neurologic outcome. Any victim with a GCS score less than 15 who has sustained a head injury should be evacuated if possible. A low or declining GCS score suggests increasing ICP. Abnormal pupil size or asymmetric pupillary responses suggest increased ICP. These clinical deteriorations demand the rapid attention of rescue or evacuation personnel to optimize MAP and CPP, minimize secondary brain injury, and prevent brainstem herniation. Injury morphology may be difficult to assess in the wilderness setting and relies on level of suspicion and clinical signs and symptoms. After attention to the primary survey, including airway provision and spinal immobilization, the physical examination component of the secondary survey is imperative and can provide information about the presence of a TBI.

Injury Classification

Intracranial injuries range from concussion to massive subdural hematoma. Subdural hematomas are more common than are epidural hematomas, constituting 20% to 30% of mass lesions. “Subdurals” result from torn bridging veins between the cerebral cortex and draining venous sinuses. Their prognosis is worse than that of “epidurals,” although prompt recognition and drainage improve patient outcome. Epidural hematomas are most commonly located in the temporal region and result from injury to the middle meningeal artery, often associated with a fracture. These patients may present with loss of consciousness, followed by a lucid interval and subsequent rapid neurologic deterioration. This sequence, however, is not frequently observed. Hemorrhagic contusion is also quite frequent, constituting 35% of traumatic injuries, and has the propensity to significantly increase ICP. Diffuse axonal injury (DAI) is the term used to describe prolonged post-traumatic coma not resulting from a mass lesion or ischemic insult. Similar to hemorrhagic contusion, diffuse axonal injury may result in elevated ICP.

Physical Examination

After the primary survey and initial attempts to resuscitate the victim, a more complete physical examination should be done. However, this examination should not delay patient evacuation. A hallmark of TBI is altered level of consciousness. Determination of the GCS score aids in recognition of TBI and should be regularly reassessed to provide a mechanism for quantifying neurologic deterioration. Physical signs that may denote underlying brain injury include significant scalp lacerations or hematomas, contusions, facial trauma, and signs of skull fracture. Findings specific for basilar skull fracture include ecchymosis behind the ears (Battle’s sign) and periorbital ecchymosis (raccoon eyes). Blood behind the tympanic membrane on otoscopic examination (hemotympanum), frank bleeding from the ears, and CSF rhinorrhea/otorrhea also suggest skull fracture and underlying TBI.

The pupillary examination may provide valuable data in assessing underlying TBI. Herniation of the temporal lobe of the brain may be heralded by mild dilation of the ipsilateral pupil with sluggish response to light. Further dilation of the pupil followed by ptosis (drooping of the upper eyelid below its normal level), or paresis of the medial rectus or other ocular muscle, may indicate third cranial nerve compression by a mass lesion or herniation. Table 21-2 relates pupillary examinations to possible underlying brain lesions. Most dilated pupils (mydriasis) are on the ipsilateral side to the mass lesion. With direct globe injury, traumatic mydriasis may result, making evaluation of TBI more difficult. In addition, 5% to 10% of the population has congenital anisocoria (a normal difference in pupillary size between the eyes). Casual inspection may overlook a prosthetic eye, which is mistaken for a fixed pupil. Neither direct trauma nor congenital anisocoria should be assumed in a head-injured victim exhibiting mental status change in the wilderness.

TABLE 21-2 Interpretation of Pupillary Findings in Head-Injured Victims

Pupil Size	Light Response	Interpretation
Unilaterally dilated	Sluggish or fixed	Third nerve compression secondary to tentorial herniation
Bilaterally dilated	Sluggish or fixed	Inadequate brain perfusion; bilateral third nerve palsy
Unilaterally dilated or equal	Cross-reactive (Marcus Gunn)	Optic nerve injury
Bilaterally constricted	Difficult to determine; pontine lesion	Opiates
Bilaterally constricted	Preserved	Injured sympathetic pathway

After quantification of GCS score, pupillary examination, and examination of the head and face for signs of external trauma, a concise neurologic examination should be performed. The goal of the field neurologic examination is to identify motor or sensory focal deficits suggestive of intracranial injury. Sensory deficits follow the general dermatome patterns shown in Figure 21-3. Unilateral hemiplegia may signify uncal herniation resulting from mass effect in the contralateral cortex because of compression of the corticospinal tract in the midbrain. Ipsilateral pupillary dilation associated with contralateral hemiplegia is a classic and ominous sign of tentorial herniation. Deep tendon reflex changes in the absence of altered mental status are not indicative of TBI. Detailed evaluation of brainstem function cannot be undertaken in the wilderness setting. Performance of gag and corneal reflex evaluations may provide some information helpful in triage and evacuation planning, but their presence would not automatically obviate the need for prompt evacuation.

FIGURE 21-3 Dermatome pattern, showing the skin area stimulated by spinal cord elements. Sensory deficits follow general dermatome patterns.

Resuscitation

Resources and circumstances permitting, resuscitation should be initiated as an adjunct to the primary survey. The primary focus for the head-injured victim, similar to any traumatized victim, is the airway. During the primary survey and performance of the ABCDE sequence, IV access should be established. If IV resuscitation is impossible, it is not advisable to administer fluids orally to the victim with head injury because of the likelihood of vomiting, airway compromise, and aspiration.

Individuals sustaining head trauma have a high incidence of concomitant injuries. Up to 32% of persons with severe head injury have a long bone or pelvic fracture, 20% to 25% a chest injury, and 10% an abdominal injury. A victim who does not have a palpable femoral pulse or presents with other signs of hypotension in the context of suspected head injury must not be assumed to have a neurogenic etiology of shock, so other etiologies must be thoroughly and aggressively investigated. Resuscitation is critical in the setting of head injury for multiple reasons. Management of a head injury should be secondary to other life-threatening injuries, which, if not addressed, may preclude survival. As previously discussed, maintenance of MAP (and thus CPP) is critical in preventing secondary brain injury.

The type of resuscitative fluid administered to trauma victims continues to be controversial. Previously, recommendations warning of the dangers of overhydration in head injury led to recommendations restricting fluids. Restriction of fluid has not been shown to reduce ICP or edema formation in laboratory models of TBI. Theories about limiting cortical free water content in TBI by using hypotonic IV solutions have not been borne out in animal studies.⁸⁸ The need for resuscitation and intravascular volume support has been well established. Possible resuscitative fluids include isotonic crystalloids, hypertonic crystalloids, or colloid solutions. There is convincing evidence that hypotonic fluids are not appropriate in TBI secondary to an increase in whole-brain water content and subsequent elevation in ICP. Recent data from animal studies of TBI suggest that colloid solutions offer no advantage over isotonic crystalloids, such as lactated Ringer’s solution, in terms of augmenting CBF or preventing cerebral edema.⁹⁷ As previously noted, no prospective trial has clearly documented an advantage of colloid over crystalloid administration in the victim with multiple systemic injuries. Evidence is accumulating that hypertonic solutions, particularly hypertonic saline, may be beneficial in TBI.^90,⁹⁴ However, an advantage has not been demonstrated in trauma victims overall, and expertise is necessary for their use. The recommended resuscitative fluid for the head-injured victim in the wilderness setting is isotonic crystalloid, with a target MAP of 85 to 95 mm Hg based on cuff blood pressure determinations or extrapolation from distal pulses evaluation.

Further Management

Numerous adjuncts exist in the management of the head-injured victim, few of which are applicable in the wilderness setting. Once the primary and secondary surveys are complete, the airway is secured, resuscitation has been initiated, and spine immobilization has been achieved, the victim should be placed in a 30-degree head-up position. This position assists in control of ICP, and thus CPP, through augmentation of venous outflow. This maneuver should not be attempted if the spine cannot be adequately immobilized.

If endotracheal intubation is possible, ventilation should be optimized without hyperventilating the victim. Hyperventilation has been used aggressively in the past to promote hypocarbia-induced cerebral vasoconstriction, theoretically to decrease brain swelling. However, if the PaCO₂ falls below 25 mm Hg, severe vasoconstriction ensues, effectively reducing CBF, promoting ischemia, and possibly augmenting secondary brain injury. Studies have demonstrated worse outcomes in victims with severe head injury who were hyperventilated.⁶⁷ Inability to measure or titrate PaCO₂ in the wilderness mandates that respiration be controlled to approximate near-normal minute ventilation.

All bleeding from the scalp or face should be controlled with direct pressure. Scalp hematomas, regardless of size, should not be decompressed. Open wounds, particularly skull fractures, should be irrigated and covered with the most sterile dressing available. Fragments of displaced cranium overlying exposed brain tissue should not be replaced. If signs of skull fracture are present, broad-spectrum antibiotic prophylaxis and immunization against tetanus are recommended as soon as possible.

Although diuretics have been widely used in the intensive care management of intracranial hypertension, no rationale exists for their use in the field. The wilderness trauma victim may have many injuries that are impossible to evaluate fully in the field. In this setting, particularly in the presence of hemorrhagic shock, attempts to induce osmotic diuresis to decrease ICP may be life-threatening. Diuretics such as furosemide or mannitol may exacerbate hypotension, cause metabolic alkalosis, and induce renal complications in the absence of physiologic monitoring.² Corticosteroids have no role in head injury in the field or intensive care unit. Studies have documented no beneficial impact on ICP or survival. Attempts at brain preservation by slowing metabolic rate and oxygen consumption have no role in the wilderness setting. Barbiturates have been used for elevated ICP refractory to other measures, but may induce hypotension, depress myocardial function, and confound the neurologic examination.² Compared with minimizing ICP, these interventions offer no significant benefit.³⁹

Approximately 15% of persons with severe head injury experience post-traumatic seizures. Phenytoin, if available, can be safely administered in the field, but only after a witnessed seizure. Prophylactic administration has not been shown to decrease long-term seizure activity.

Skull Fracture

Skull fracture in the wilderness mandates evacuation. Therapeutic options in the field are few, with intervention limited to identifying the injury and arranging rapid transport. Skull fractures may be open or closed, linear or stellate, and may occur in the vault or skull base. These fractures are associated with a high incidence of underlying intracranial injury. Skull fractures with depression greater than the thickness of the skull may require elevation. No attempt at elevation should be made in the field. Any exposed brain surface should quickly be covered with the most sterile covering available, preferably moistened with crystalloid solution. Loose bone or brain fragments should not be manipulated. If a broad-spectrum antibiotic is available, it should be administered. After attention to the wound and stabilization of associated injuries, the victim should be rapidly evacuated.

Penetrating Head Injuries

The majority of penetrating head injuries in the wilderness are gunshot wounds, although knives and arrows may penetrate the cranium. Such penetrating injuries are usually catastrophic. However, examples of survival exist with small-caliber, low-velocity injuries and tangential wounds.⁵⁹ As with closed head injury, management priorities consist of maintenance of airway, prevention of secondary brain injury, and rapid evacuation. If the cranium has been violated, the victim should receive antibiotics and tetanus immunization in the same manner as for open skull fracture. In the rare instance that the projectile is embedded in the skull, no attempt at removal should be undertaken. If the length of the projectile makes immobilization or transport cumbersome, excess length may be removed, but only if this can be done without displacement of the intracranial segment.

Evacuation

Survival and outcome of head injury in the wilderness correlate directly with rapidity of evacuation. Certain situations dictate immediate evacuation. Any person with evidence of an open or closed skull fracture should be evacuated. The incidence of TBI associated with skull fracture is variable but significant throughout the literature. Recent data predict that 30% to 90% of persons with raccoon eyes or Battle’s sign will show abnormalities on computed tomography (CT) scan.^11,¹⁷ Similarly, any person who sustains a penetrating injury should be evacuated. Decisions concerning evacuation of victims who have sustained closed head injuries can be simplified by dividing the victims into three groups based on probability of injury. A high-risk group, defined as patients with a GCS score of 13 or less, focal neurologic signs, or evidence of decreasing level of consciousness, requires evacuation. The low-risk group includes persons who have suffered a blow to the head but are asymptomatic, did not lose consciousness, and complain only of mild headache or dizziness. Data from recent studies suggest that persons who meet low-risk criteria (including a GCS of 15, no loss of consciousness, minimal symptomatology, and unlikely mechanism) have a minimal chance of having significant TBI and may be closely observed.^11,¹⁷

This group includes patients who have suffered a concussion. The Quality Standards Subcommittee of the American Academy of Neurology ⁷⁸ defines concussion as a trauma-induced alteration in mental status that may or may not involve the loss of consciousness. The neurologic impairment is short-lived and resolves spontaneously without any structural injury to the brain. Close observation includes awakening the patient from sleep every 2 hours and avoidance of strenuous activity for at least 24 hours. The following signs indicate more advanced medical care is necessary: (1) inability to awaken the patient; (2) severe or worsening headaches; (3) somnolence or confusion; (4) restlessness, unsteadiness, or seizures; (5) difficulties with vision; (6) vomiting, fever, or stiff neck; (7) urinary or bowel incontinence; and (8) weakness or numbness involving any part of the body.⁵¹ No prospective validated guidelines for return to activity have been established. Generally, one should not return to an environment in which concussion is a risk (e.g., contact sports) until symptoms have been absent for 7 days.

Patients with a predisposition to bleeding need a much more aggressive approach requiring evacuation and evaluation at a higher level of care.

The group for which the evacuation decision is most difficult is the moderate-risk group. These persons have a history of brief loss of consciousness or change in consciousness at the time of injury, or a history of progressive headache, vomiting, or post-traumatic amnesia. If any of these signs is present in the face of concurrent systemic injury, the victim should be evacuated immediately. Studies associating clinical variables and abnormal results on CT scan have demonstrated the significance of decreased GCS score, symptoms, and loss of consciousness. If these signs are present in isolation and the evacuation can be completed in less than 12 hours, the evacuation should proceed. If the evacuation is impossible or will require longer than 12 hours, the victim should be closely observed for 4 to 6 hours. If the examination improves to normality during the observation period, it is reasonable to continue observation.

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