The daily operations of EMS systems focus on providing care and transport to individual patients with (usually) unlimited resources. This approach allows prehospital providers to attempt to maximize the chances of an individual’s survival and reduce the morbidity they may experience from their injury or illness. In situations involving multiple/mass casualties incidents and disasters, the principles of “routine” field triage and transport decisions can change significantly, as the goals of patient care shift from doing the most good for a singular patient, to doing the most good for the most patients. Recognizing the regional variability inherent in prehospital emergency care, it is imperative for EMS physicians to understand the concepts in this chapter globally, but also to apply and understand them in the context of their local/regional EMS system(s). Specific aspects of daily operations are discussed elsewhere in the text.

• 
  

  Describe the theory behind the need for trauma triage in mass casualty incidents.

  
  
• 
  

  Describe the major field triage methods, and detail their use.

  
  
• 
  

  Describe the medical triage, transport, and treatment areas setup during an MCI.

  
  
• 
  

  Discuss the role of the EMS physician in assisting the triage officer(s) and transport officer(s) in their duties.

  
  
• 
  

  Discuss the pros and cons of the EMS physician limiting their role to aiding in the treatment area during an MCI.

  
  
• 
  

  Discuss field triage and retriage in prolonged events, or during times of limited hospital/transportation resources.

Triage, from the French trier meaning to sort, is a term initially ascribed to the process of sorting coffee beans. The transition from an agrarian process to a part of the medical evaluation process began with the efforts of Baron Dominique-Jean Larrey, Chief Surgeon of Napoleon’s Army. Baron Larrey is credited with devising a system to identify and sort casualties of war on the battlefield and evacuate them via ambulances volantes to field hospitals.¹ In this first use of medical triage, the goal was to identify soldiers with injuries that were survivable, with focus placed on providing the care needed to return the soldier to the battlefield as quickly as possible in order to maintain a sufficient fighting force. Following the Napoleonic wars, the battlefields of subsequent military engagements saw further refinement of the triage processes as the technology of health care and warfare developed. The development of antibiotics and advanced surgical techniques, recognition and treatment of shock, utilization of helicopters, and institution of “buddy care” to initiate immediately lifesaving interventions all had a significant role in the reduction of combat fatalities from a rate as high as 30% during World War II to a rate of less than 10% in the Afghan and Iraqi wars.¹

As with much of our present-day trauma care practices, civilian triage methods were subsequently derived from wartime practices that have been adapted to peacetime needs stemming from natural, industrial, and criminal/terror-related disasters and multiple/mass casualty incidents. Now, the medical literature is plentiful with acronyms such as START, JumpSTART, SAVE, SALT, and TSS, and products such as triage kits containing color-coded tags, flags, tarps, vests, and other items are common in the consumer retail markets. For the end user, it can be challenging to determine which of several protocols and products are best chosen and implemented to maximize survival rates while maintaining a triage method that is cost-effective. One of these challenges is the lack of a universally accepted triage standard.

Several challenges exist behind the development and utilization of current triage methods, not the least of which is a paucity of evidence-based information on which to critically assess the accuracy and effectiveness of these schemes.

According to the World Health Organization, a disaster occurs when “normal conditions of existence are disrupted and the level of suffering exceeds the capacity of the hazard-affected community to respond to it.”² The World Medical Association goes on to explain “from the medical standpoint, disaster situations are characterized by an acute and unforeseen imbalance between the capacity and resources of the medical profession and the needs of survivors who are injured or whose health is threatened, over a given period of time.”³

Disasters are usually on a very large scale and involve a large geographic area, with examples including the 2010 Haiti earthquake, Hurricanes Katrina and Rita in the US Gulf Coast in 2005, and the 2004 Indian Ocean Tsunami. More common are mass casualty incidents (MCIs), defined as “a situation that places a significant demand on medical resources and personnel but in which local response capabilities are not overwhelmed despite a large number of patients requiring triage and medical treatment.”⁴

In our daily prehospital and inhospital medical care, we expend significant resources with the goal of providing the greatest chance of survival for individual patients, that is, providing the “greatest good for the individual.” In the vast majority of events, scarcity of resources during disasters and MCIs necessitates a paradigm shift toward rationing and equitable utilization of resources so we may provide the “greatest good for the greatest number.”⁵ In very limited circumstances, an exception to this premise exists. The concept of reverse triage deserves special mention with regard to the overall concept of utilization of resources. Two applicable definitions of this term apply. In the civilian setting, reverse triage refers to focusing care resources on the most critically injured or “expectant” patients. In this form, reverse triage is specifically applicable to the allocation of resources for multiple victims of a lightning strike, where there is a high potential for survivability of patients in cardiac arrest if they receive prompt CPR and defibrillation. For further discussion of care of the lighting-strike victim, the reader is referred to Chapter 47. In the military or tactical setting, reverse triage refers to prioritization of resources to the least injured personnel in order to return them to duty as quickly as possible in order to maintain strength of defending forces or control of the tactical environment. After an appropriate fighting or defensive/protective force is preserved, care can be provided to more critically injured personnel who are deemed salvageable by applicable triage and treatment schemata based on the combat or tactical environment and available treatment and evacuation resources.

Triage exists as part of a larger, comprehensive and integrated response to an MCI or disaster. As such, it must be recognized that triage operations do not exist in a silo, as they are affected by and affect the actions of other responding entities. Bostick et al discuss a concept of systemic triage and define four orders of triage that occur in the recognition, response, and recovery stages of a disaster.⁶

In systemic triage, first-order triage is established in the general community that may be or has been affected by the incident. First-order triage is used by public health to help disseminate information that may help prevent injury, decrease exposure to a threat, and help resources from becoming overwhelmed by providing risk-specific information to the community about appropriate self-protection practices, indications for seeking medical care, and appropriate venues to seek shelter or care. Examples of steps taken in first-order triage may be shelter in place, community evacuation, or specific disease call centers such as the Canadian SARs Hotline. Second-order triage occurs in the prehospital setting and involves the identification, sorting, treatment, and evacuation of casualties to appropriate locations for definitive care. Third-order triage occurs at sites of secondary or definitive care and involves assessment of the medical needs of arriving patients, stabilization and transfer to definitive care, or provision of definitive care. Use of treatment protocols and redistribution of patients are actions taken in this order of triage. Finally, Fourth-order triage occurs at the regional level and involves monitoring of the disaster and appropriate resource allocation, including actions like activating the strategic national (pharmaceutical) stockpile or redistributing human, supply, and equipment resources within the affected area.⁶ Such a systemic approach allows for integration of the disaster response entities and maximizes the potential for increased casualty survival at each point of contact with victims and those at risk for disaster-related injury or illness. The coordination of response that is established by systemic triage is needed in order to provide victims of an MCI or disaster equal opportunity of survival, meaning all affected individuals are afforded equity in triage and the receipt of medical care that is consistent with their injuries and projected survivability, as well as prevailing resource constraints. This notion of equal opportunity in triage does not, however, guarantee either treatment or survival for all patients potentially affected by a catastrophic event.⁶

This chapter will focus second-order triage, the operations of triage in the identification of patients, their categorization, and prioritization for treatment and evacuation from an MCI/disaster scene. For more discussion regarding the role of EMS in disaster response, please see Section 12.

With the exception of chemical, biologic, radiation, and nuclear (CBRN)-related events, an important concept to recognize about patients injured in disasters and MCIs is that their injuries tend to be similar to those that medical providers encounter in their regular daily trauma care.⁵ Thus, most prehospital providers already possess the skills needed to evaluate and care for these patients. Although fortunately, as Frykberg discusses, “the great majority of initial survivors are not critically injured,” the often large number of noncritical patients who must be assessed may make it more difficult to identify and provide immediate treatment to the 10% to 25% of patients who are critically injured.⁵ Additional challenge exists in determining which patients may or may not be salvageable, and one of the most difficult principles for triage providers to adapt to is that circumstances may require them to abandon casualties that would normally (in day-to-day operations) undergo heroic measures regardless of their chances of survival.

CBRN events may add an additional level of complexity to the assessment of disaster and MCI victims. This is especially true because most EMS providers do not usually encounter patients injured by CBRN mechanisms during their daily operations and thus have less experience and potentially less knowledge and understanding of disease and toxicology mechanisms on which to base their assessment and categorization of CBRN injured patients. The issues of EMS provider safety, when, which type, and how to use personal protective equipment, and when, where, and how to perform patient decontamination increase the complexity of triage decisions.

Victims of chemical exposure may experience immediate or delayed injuries in the absence of physical trauma. Patients may initially be well-appearing casualties that later deteriorate and experience life-threatening conditions such as cholinergic toxicity. Thus frequent retriage is a necessity. Providers also face challenges in the provision of immediately lifesaving treatment of chemically injured victims due to the availability, efficacy, and difficulty in administration of antidotes (ie, atropine and 2-PAM autoinjectors, the number of doses needed for effective treatment, etc). Furthermore, chemically exposed patients may pose an exposure risk to rescuers and require decontamination, which can slow the progress of moving patients from an incident scene to primary treatment and evacuation areas. Chemical-related events may occur in a discrete area or may be dispersed over a large geographic area depending on prevailing weather conditions and the nature of the chemical agent (a gas, vapor, or liquid).

Unlike chemical exposures, biologic exposures are unlikely to cause immediate injury and may have a latency period typically on the order of days. Although the initial exposure may have occurred at a discrete location, when patients begin to exhibit symptoms of their exposure they are unlikely to be confined to a discrete scene (ie, distributed over a larger geographic area). Therefore, the utilization of most primary triage methods is less likely to be effective during a biologic event.

The threat of a radiation exposure must be considered when developing a triage method that can be applied to “all hazards.” Although capable of inflicting a significant psychological impact on a large population, radiation dispersion devices (RDD) or dirty bombs are more likely to inflict life-threatening traumatic injury that is a direct result of the explosion/blast forces rather than immediately life-threatening injury from the radiation exposure itself. Unless a patient is contaminated with radioactive material, the radiation-exposed patient poses no radiation risk to the rescuer (ie, a patient who gets an x-ray is exposed to radiation, but is not a risk to other people). Although the number of physically injured victims may be small, the psychological impact of RDDs may result in a large number of “worried well.” While these patients are not likely to consume physical medical resources (medications, wound care supplies, etc) they do consume a significant number of personnel resources as they seek assessment and medical care. When considering the primary causes of injury in a dirty bomb event, it has been suggested that “no substantial revisions need to be made to MCI triage methods to account for radiation exposure.”⁷

In difference to an RDD event, victims from a nuclear event are likely to suffer life-threatening injuries resulting from blast, thermal, and ionizing radiation mechanisms. The type of radiation exposure (α and β particles, and γ-rays), intensity of exposure, degree of contamination, and duration of exposure are likely to be higher in a nuclear event compared to an RDD detonation. Because sources of ionizing radiation are dispersed in the environment, ongoing exposure can occur for both victims and rescuers who remain in the primary contamination zone. Patients close enough to the source of the nuclear incident to receive enough radiation exposure to result in acute radiation sickness are also likely to be within the primary lethal blast zone (blast area roughly double the area where “survival possible” exposure of 2 to 4.5 Gy.⁸

A common theme among many of the literature resources reviewed for the development of this chapter is discussion regarding the lack of sufficient data on which to base evaluation of the efficacy of existing triage methods. Of the few articles that have attempted to validate existing triage methods, because there is little existing data available regarding outcomes from real-life utilization of triage methods to actual MCIs and disasters, most studies are based on data surrogates such as retrospective application of protocol assessment criteria to patients in trauma registries. Considering that prospective assessment of a particular triage method is likely impossible due to barriers in predicting disasters, lead time in training providers, and certain ethical challenges, the use of these surrogates for data and efficacy assessment are necessary.

In addition to the lack of adequate data, many articles also cited the lack of a universally accepted gold standard or outcome measure with which to compare various triage methods. However, several different concepts have been identified as critical variables that must be considered when evaluating or developing a triage method.

Frykberg discusses the concept of the critical mortality rate, the percentage of deaths only among the critically injured, suggesting that “the outcome of critically injured casualties is the best indication of the success of medical care in an MCI.” By using this measure, triage methods would be compared based on their ability to identify and correctly categorize the critically injured patients, and would be judged on this specific survival score rather than on the overall disaster mortality rate (which would include the on-scene/immediate deaths as part of the entire fatality census).⁵

Several factors may influence the critical mortality rate achieved by a particular triage method. Ideally a triage method would correctly categorize each patient 100% of the time. However, certain rates of undertriage, inappropriate assignment of critically injured victims with life-threatening problems to a delayed category, and overtriage, assignment of noncritical casualties to immediate care, often occur. Undertriage places critical patients at risk of not receiving appropriate priority for treatment and transport. This may occur when victims have somewhat innocuous appearing injury patterns externally, but have significant internal injury (ie, small penetrating trauma from shrapnel). Conversely, casualties that have severe external injuries but have a low likelihood of survival may be overtriaged to the immediate category, rather than an “expectant” category. In either case, overtriage will lead to the consumption of resources that would best be utilized to care for the true “immediate” patients. Of the two, studies of MCI bombing events indicate that overtriage has been shown to have a greater negative impact, illustrating “a direct linear relationship between the rate of overtriage and the critical mortality rate of survivors”.⁹

Both over- and undertriage can be an effect of the triage method or of the rescuer who is using the method. Intrarater reliability occurs when an instrument results in identical triage categorization if the same evaluator rates the same patient twice within a short time period.¹⁰ Interrater reliability occurs when an instrument results in identical triage categorization of the same patient when evaluated by two different raters.¹⁰ In a well-developed triage method, rates of intra- and interrater reliability would be high.

When authors discuss the “testing” of a triage method, it is important to understand exactly what is being tested. Is one testing whether the scheme can predict patient outcomes, whether providers use the scheme accurately, or whether use of the scheme improves outcomes? In other words, when looking at the patient outcomes when a particular triage method has been utilized, it may be difficult to separate whether there was a success or failure of the tool itself, or success or failure in the ability of the providers to accurately/correctly use the tool.

The concept of construct validity, the ability of a test or process to assess what it is intended to assess, can be applied both to the validity of the triage method and in the tools used to assess the effectiveness of the method.¹¹ The construct validity of several primary triage methods (START, SMART, CareFlight) has been assessed in a few studies, but no such assessment has been applied to secondary triage methods.¹⁰

In the initial chaos of an MCI or disaster, a certain amount of inaccuracy of triage must be expected and accepted. This inaccuracy can be mitigated, however, by utilizing secondary and tertiary triage at each point in the patient evacuation process (ie, arrival at a treatment zone, just prior to departure from a treatment zone, upon arrival at a destination hospital, etc). Such serial reassessments can help increase the accuracy of their diagnosis, can increase triage accuracy, and decrease the rates of under- and overtriage.

Several triage methods have been proposed, and they are utilized to various degrees across the United States and internationally. In 2008, a consortium of specialists was convened in the United States to develop and propose a national standard triage guideline. In their review of existing literature and products, they identified nine existing triage methods. Several commonalities were identified between these systems, although it was found that there is a lack of uniformity in aspects such as patient assessment principles and commonality of language (ie, Priority I, II, III; Immediate, Delayed, Minimal; Emergent, Urgent, Nonurgent, etc) that may result in confusion, especially if neighboring jurisdictions use differing triage methods. This panel focused their efforts on reviewing primary triage methods, including START, JumpSTART, Homebush, Triage Sieve, Pediatric Triage Tape, CareFlight, Sacco Triage Method, Military Triage, and CESIRA. Table 53-1 provides a summary comparison of these primary triage methods.