Protocols of Care at the Site of Injury
Hemorrhage is the major cause of death in combat casualties.
— Ronald Bellamy, M.D., 1998
A valid approach to fluid resuscitation in the wounded combatant should be based on both military considerations and scientific evidence. In Chapter 1, we reviewed the nature of combat injuries and the importance of treating severe blood loss on the battlefield. Chapter 2 outlined the major pathophysiologic events in hemorrhagic shock. Chapter 3 summarized the laboratory evidence and clinical experiences with various resuscitation fluids. Next, it is necessary to consider the specific needs of the injured combatant in a far-forward area, so that treatment protocols can be developed to address those needs. This chapter provides an overview of the combat environment, describes the resuscitation needs of the injured combatant, and makes recommendations for immediate treatment on the battlefield.
The Combat Environment
As mentioned in Chapter 1, the battlefield of the 21st century will likely differ from that of the past in scale and pace. The U.S. military expects that future battles will be fought by smaller groups of combatants, over shorter time intervals, and with fewer casualties at any point in time (Secretary of Defense, 1999). Future battles, however, are expected to be fought in challenging settings, such as cities and towns or remote areas where air and ground transport may be difficult (Bruttig, 1998). These new battlefield environments have implications for the physical condition of the combatant, and for the type of care that should be provided in the field.
Expected Condition of Combatant on the Battlefield
The U.S. military expects that military operations in the near future will more frequently resemble activities of the Special Operations forces (Secretary of Defense, 1999). That is, conflicts will develop quickly and troops will be delivered to the battlefield on short notice, as compared with prior wars that involved large numbers of ground troops engaged in prolonged conflicts over large areas. Because of the rapid deployment, it is unlikely that combatants will be chronically dehydrated or malnourished. However, engagements may take place in desert or arctic environments as well as in jungles or mountainous regions. Precipitation, humidity, altitude, and extremes of hot and cold can all affect the condition of the combat casualty.
Limits of Battlefield Care for the Injured Combatant
Although many of the approaches to trauma care evolved from clinical research in the civilian sector, there are substantial differences between the injured combatant and the injured civilian. Civilian trauma patients encompass a broad spectrum of age, weight, coexisting disease, and cardiovascular conditioning. In addition, ethanol or illicit drug intoxication is a frequent component of civilian trauma. In contrast, military combatants are uniformly young, healthy, and physically fit, and ethanol or drug intoxication is a rare occurrence on the battlefield. As described in Chapter 1, battlefield injuries differ from those in the civilian sector in that civilian injuries often involve blunt trauma, whereas penetrating wounds are more common on the battlefield. Penetrating injuries in civilians are the result of bullets or knives, whereas penetrating battlefield wounds are usually due to shrapnel. Finally, civilian trauma is commonly associated with very rapid transport to an advanced medical facility (emergency department or trauma center), whereas military medical transport is often delayed for the wounded combatant.
Fluid therapy and other first-line treatments also differ between military and civilian environments. Battlefield care is characterized by limited resources, limited expertise, and delayed transport to medical facilities. Initial combat care is often provided by a medic or other combatant who carries limited medical supplies in addition to weaponry. Approaches to battlefield care and fluid resuscitation must be designed for the remarkably challenging conditions that face the first responders who care for casualties in far-forward deployment areas.
Because of the likely locations of future conflicts, immediate evacuation by air may be difficult or impossible. As a result, initial and even ongoing treatment of casualties may be significantly extended. As mentioned above, lifesaving medical treatment may well come from a fellow combatant or a medic—both of whom are included in the term "first responder." First responders are likely to be young, inexperienced in combat, and without medical training or experience.
Often, they will need to initiate immediate care while under fire, returning fire, or otherwise consumed by the chaos and confusion of battle.
Appropriate fluids and fluid protocols will play an integral part in the preservation of life until the wounded can be evacuated to a site where advanced medical expertise is available. Because the military first responder is severely limited in what he or she can carry into the field, approaches to resuscitation as well as other therapies must be streamlined and efficient. Supplies and equipment must be of low weight and small volume. Initial treatment protocols must consider both the needs of the average wounded combatant and the limitations of the battlefield environment.
Resuscitation Needs of the Injured Combatant on the Battlefield
For the reasons stated above, initial treatment protocols must be simple and should focus on the most critical needs of the typical combat casualty. Those needs are (1) establishing or ensuring an adequate airway and breathing, (2) controlling external hemorrhage, and (3) fluid resuscitation of hypovolemia and shock. In addition, the first responder must initiate and facilitate rapid evacuation to deliver live casualties to organized medical care behind the lines of battle. Critical tasks for resuscitative care include:
- establishment of an adequate airway,
- control of massive hemorrhage,
- circulatory support by intravascular fluid replacement,
- detection and treatment of hemo- or pneumothorax (including tension pneumothorax), and
- immobilization of fractures.
Immediate Versus Delayed Fluid Resuscitation
Regarding the unresolved issue of immediate versus delayed fluid resuscitation, Bickell and colleagues (1994) reported interesting findings in an inner city served by an efficient paramedic system with short times of transport to definitive care. These investigators concluded that the group of patients in whom fluid resuscitation was delayed had a lower mortality rate. Because the transport times were far shorter than they would be in the battlefield, it is not clear that their findings would apply to the military setting. In addition, the methodology of that work has been criticized on the basis of the lack of comparability of the two treatment groups, bias in patient selection, the small difference in the actual amounts of fluids that the two groups received in the prehospital setting, and the differences in the times to operative intervention. In view of the above and the likely delays to definitive therapy in the combat environment, immediate fluid resuscitation seems more appropriate for wounded combatants.
Certain small subsets of military combatants (notably Special Operations forces corpsmen and medics, referred to as "trained responders" below) receive training based on the Advanced Trauma Life Support® (ATLS®) course (American College of Surgeons, 1997). Essential elements of this approach include control of hemorrhage, airway and breathing support, and intravenous fluid resuscitation.
Because exsanguination is the single major cause of death in potentially salvageable battlefield casualties (see Chapter 1), control of external hemorrhage, preferably by pressure but even by tourniquet if necessary, is an essential and immediate priority. The effectiveness of subsequent fluid resuscitation will depend greatly on the extent to which bleeding is controlled.
According to ATLS® protocol, the trained responder should ensure that the airway is clear. If the wounded combatant is conscious and breathing, then airway intervention is not necessary. If the wounded combatant is unconscious and respiration is labored, efforts should be made to clear the airway. The first approaches involve the chin-lift or jaw-thrust maneuvers. When clearing the airway of the unconscious victim on the battlefield, the first responder should not worry about cervical spine immobilization, because cervical spine injury is uncommon in combatants (Butler et al., 1996). Attention to cervical spine immobilization is secondary to evacuation from the front line.
Tension pneumothorax may also cause inadequate breathing. As noted in Chapter 1, 10 percent of the deaths in the battlefield during the Vietnam conflict were due to tension pneumothorax. Successful treatment of battlefield injuries requires that this condition be addressed by the trained responder (Coats et al., 1995; Deakin et al., 1995; Glinz, 1986; Krome, 1983). As outlined by Butler and colleagues (1996), respiratory distress occurring in a combat casualty with a penetrating chest wound should be assumed to represent tension pneumothorax. The diagnosis of a tension pneumothorax can be strengthened by visually identifying other signs, but this is not essential and may not be possible at night or while under fire. Although the trained responder will likely be inexperienced with needle thoracostomy, any additional trauma caused by this intervention is not expected to worsen the combat casualty significantly, whether or not a tension pneumothorax is present (Cameron et al., 1993). Current protocols used by Special Operations forces medics for treatment of injury on the battlefield are summarized in Box 5-1.
Items 1 through 5 of the protocol in Box 5-1 relate to the special focus of this committee. The committee finds at least two limitations to these approaches: (1) the use of large-volume (1,000 ml) solutions limits their availability on the battlefield, and (2) fluid resuscitation protocols based on intravenous access limit the number of personnel who could provide care on the battlefield. Together, these limitations inevitably restrict fluid resuscitation to only a few of the many who might benefit from such treatment. Both limitations are addressed as part of the committee's conclusions and recommendations.
BOX 5-1 Basic Tactical Casualty Management Plan for U.S. Special Forces Medics
Conclusions and Recommendations
The greatest opportunity for reducing the rate of mortality among combat casualties occurs on the battlefield. Unfortunately, the battlefields of the future may be less accessible than those of the past. Because conflicts in high-density urban or remote locations may lead to delays in evacuation by air, the committee concluded that immediate and subsequent ongoing treatment of casualties in far-forward areas should be improved. The committee's recommendations address approaches to the targets of injury, protocols for treatment in the field, and methods of evaluating and improving these protocols in the future.
Training First Responders
Initial care can be improved substantially by training more combatants to administer lifesaving measures to their fellow soldiers. The Israeli army trains half of its combatants to be medics. Although this may be unrealistic for the U.S. military, small mobile combat units should include a significant number of individuals with emergency medical training to provide the care that is outlined below. Larger units would require a smaller percentage of combatants so trained. Today there are excellent courses—such as the Prehospital Trauma Life Support (PHTLS) advanced trauma life-support course for prehospital providers developed by the American College of Surgeons (McSwain et al., 1994), the Basic Trauma Life Support (BTLS) advanced trauma life support course for prehospital providers developed by the American College of Emergency Physicians (ACEP) (Campbell, 1996), and the British Battlefield Advanced Trauma Life Support (BATLS) course—which could be used as a structure on which to base such training. The signs and symptoms of shock or tension pneumothorax, and all of the medical interventions recommended below, are taught in these courses. In view of the marked differences between the battlefield conditions and the civilian environment, the committee believes that it would be valuable to design a modified ATLS® course (Military Trauma Life Support) to train significant numbers of military first responders who could supplement the efforts of corpsmen and medics.
Recommendation 5.1 The number of trained first responders in the combat environment should be increased through development of a Military Trauma Life Support course.
Available Approaches for Treatment of Injury
The injuries that are responsible for the majority of fatalities and that are potentially treatable are exsanguinating hemorrhage, airway compromise, and tension pneumothorax (Bellamy, 1984, 1987b). The resuscitation and maintenance of life in a combat casualty (or civilian trauma victim) requires multiple
skills that could be learned by first responders as described in Recommendation 5.1 and summarized in Box 5-2.
The protocol for the treatment of battlefield casualties by a single first responder is presented in the airway-breathing-circulation format. Most of these recommendations represent a departure from traditional therapies administered in the battlefield. There is ample evidence (from experience in civilian emergency medical systems) that nonphysician first responders can be trained to administer aggressive lifesaving therapies in the field. However, these skills must be taught in carefully constructed training courses and administered by simple and clear protocols. Use of these protocols will represent a new era in battlefield therapy.
The proposed protocols for the fluid resuscitation of battlefield casualties are based on a modification of those presented by the medical command of the U.S. Navy Seals (Butler et al., 1996). The goal of therapy will be to stop hemorrhage, expand volume rapidly, increase cardiac output, and sustain effective perfusion.
Based on evidence about available resuscitation fluids that is discussed in Chapter 3, taking into consideration the large number of studies that have demonstrated both safety and efficacy, the need for simplicity, the limited volume that can be carried in the field, and relative cost, the committee concluded that 7.5 percent saline should be used for immediate fluid resuscitation on the battlefield.
Recommendation 5.2 The initial fluid resuscitation of the hemorrhaging battlefield casualty should be a 250 ml bolus of 7.5 percent saline delivered by a rapid-infusion system.
First responders in the field should be equipped with a rapid systemic infusion system consisting of a small plastic bag containing a 250 ml bolus of hypertonic (7.5 percent) saline. Both the composition and amount of the initial bolus are based on clinical trials outlined in Chapter 3.
The bag containing hypertonic saline would be placed under low pressure or accompanied by a simple, sturdy pumping device that could be mechanical or electric. Systemic accesses would be achieved via an intraosseous needle (Dubick and Kramer, 1997; Guy et al., 1993), placed into the anterior tibia. In extreme conditions where time and the condition of the wounded combatant dictate, the intraosseous needle with trocar in place could be placed directly through clothing. The possibility of infection is recognized, but this could be treated at a later point. If time and the condition of the wounded combatant allow, clothing could be cut away and a sterile field obtained. Intravenous access
could be provided also, but the committee concluded that the intraosseous route would be easier to teach to nonmedical combatants.
The use of hypertonic saline is recommended only as the initial intervention until definitive fluid resuscitation can be provided by more skilled medical personnel (again, consistent with the approaches used in clinical trials). If future research justifies it, additional compounds, such as those that carry oxygen or other novel therapies (see Chapter 4), could be added to the hypertonic saline solution.
Repeat Administration of Hypertonic Saline
Repeat administration of hyper-tonic saline would depend on the environment and the wounded combatant's physical condition. Regardless, an established limit as to the total amount of hypertonic saline that is infused would be necessary to avoid the complications that could occur with large infusions (Dubick and Wade, 1994; Lyons, 1996; Vassar et al., 1990). It is recommended that a total limit of 500 ml be set, and that the second bolus be given only if there is extended time to evacuation. Since the typical combatant will be a young healthy male, the likelihood is reduced that he will be highly sensitive to perturbations that might occur from a second bolus of hypertonic saline.
Airway and Breathing
The success of any fluid resuscitation depends on continued breathing and oxygenation. Although airway maintenance was not part of the charge to this committee, it was still felt that recommendations to ensure the integrity of the airway and breathing should be made. Without such efforts, any fluid resuscitation protocol would be futile. To this end, first responders should be instructed in securing the airway by administering chin lift, jaw thrust, and the use of adjuncts such as the intubating laryngeal mask airway (LMA). The LMA has been used in Europe for a number of years (Benumof, 1992; Davies et al., 1990; Martin et al., 1993; Pennant and Walker, 1992; Pennant and White, 1993; Reinhart and Simmons, 1994; Smith and Joshi, 1993; Somerson and Sicilia, 1993; Stone et al., 1994; Tolley et al., 1992; Walker et al., 1993). Its use can rapidly be taught to lay personnel, and the success rate maintained at a high level (Davies et al., 1990; Tolley et al., 1992; Walker et al., 1993). Recent work has indicated that after 5 minutes of training, lay personnel trained to use the intubating LMA on mannequins had a 90 percent success rate, a rate maintained over a period of at least 1 week (Richard Levitan, personal communication). Proper placement should be confirmed with an inexpensive disposable end tidal carbon dioxide (CO2) device (Goldfarb and Cohen, 1990; Vukmir et al., 1991).
Tension pneumothorax is a relatively common problem in combat casualties, accounting for 10 percent of the deaths in the battlefield during the Vietnam conflict (Figure 1-2). A substantial number of civilian paramedic systems in the United States have trained their medics to recognize the major signs of a tension
pneumothorax (i.e., massive jugular venous distention, shifted trachea, and decreased breath sounds) and to treat it successfully with the relatively simple intervention of needle thoracostomy (Cameron et al., 1993; Lavery et al., 1992). In addition, segments of the military already train their medics to treat casualties with needle thoracostomies (Butler et al., 1996). It therefore seems appropriate to train military first responders similarly as a means of reducing mortality from tension pneumothorax. The committee concurs with Butler and colleagues (1996), who recommended that any combatant with severe progressive respiratory distress resulting from a unilateral penetrating chest wound should be considered to have a tension pneumothorax. When under fire, presumed tension pneumothorax should be treated by immediate needle (14 gauge) thoracostomy. When not under fire, the signs of a tension pneumothorax could be evaluated before therapy.
Recommendation 5.3 First responders should ensure that the airway of a battlefield casualty is patent and that breathing is adequate.
BOX 5-2 Summary of Treatment Protocol for First Responders in the Combat Environment
In addition to the treatment protocols and training recommendations made above, the committee identified some additional considerations. These include the need for prompt evacuation and the development and use of miniaturized physiological monitoring equipment.
Prompt Aeromedical Evacuation
The United States and many parts of Europe have seen the development of extensive sophisticated civilian aeromedical emergency care and helicopter evacuation systems (Mabry et al., 1993). In some settings, trauma patients are no more than 5 minutes from the closest aeromedical units. These systems have treated and evacuated thousands of trauma victims and have saved countless lives (DeLorenzo, 1997; Gearhart et al., 1997; Hotvedt et al., 1996; Young et al., 1998; Zalstein and Cameron, 1997). Unless conditions are totally prohibitive, the committee encourages the military to emulate the civilian sector in this regard. The long evacuation times from the battlefield that occurred as recently as Operation Desert Storm, deserve substantial attention and remediation. Resuscitation of casualties in the field will never replace definitive surgical intervention, and if mortality is to be reduced in the future, aggressive field resuscitation must be followed immediately by aggressive aeromedical evacuation.
Recommendation 5.4 If accessible, all severely injured battlefield casualties should be evacuated to a front-line high-echelon care site in less than 1 hour.
The committee endorses the use of miniaturized physiological monitoring equipment as well as the continued research into its further development (Gopinath et al., 1995; Robertson et al., 1995, 1997). These devices could provide passive monitoring of the most critical vital signs of all combatants. Specific modalities that should be monitored are:
systolic blood pressure,
end tidal CO2.
Other potentially useful monitoring systems are under development. These include cardiac output monitors and the self-contained monitoring medical litter.
These seem more suited for secondary evacuation and transport. At this time, it is unclear whether having these litters on the battlefield would be realistic. In addition, systems are needed to monitor real-time physiological data at remote sites and, in turn, to direct medical care on the battlefield based on these data.