FIELD TRIAGE

Field triage identifies severely injured trauma patients at the point of injury in the “field” and triggers a decision to transport severely injured patients to a hospital that has resources commensurate with patient needs. A common field triage decision scheme assesses the injured patient in four steps, each step linked to a determination about patient need for a level of care at a trauma center. The field triage decision scheme presented here (Figure 1), originally developed by the American College of Surgeons Committee on Trauma, was revised through an evidence-based review by an expert panel representing emergency medical services, emergency medicine, trauma surgery, and public health. The panel was convened by the Centers for Disease Control and Prevention (CDC), with support from the National Highway Traffic Safety Administration (NHTSA). Its contents are those of the expert panel and do not necessarily represent the official views of CDC and NHTSA.

Figure 1 Field triage decision scheme.

Step 1 assesses physiology; step 2, anatomy of the injury; step 3, mechanism of injury and high-energy impact; and step 4, special patient or system considerations. Effective implementation of a triage decision scheme is enhanced by simplicity within relevant steps. In other words, scheme complexity harms good triage.

Steps 1 and 2 are screens of the severity of physiologic and anatomic injury, respectively, and rapidly identify the most critically injured patients requiring transport to higher levels of care within the trauma system. The initial physiologic assessment of the patient measures vital signs (systolic blood pressure and respiratory rate) and level of consciousness (Glasgow Coma Scale). Anatomic assessment emphasizes readily visualized or identifiable anatomic injuries, to include centrally located penetrating injuries, severe musculoskeletal injuries, and consequent paralysis. Patients without apparent life-threatening physiologic or anatomic issues are then screened in step 3 for further evidence of high-energy mechanisms that increase the risk for significant injury. Certain characteristics of falls, automobile crashes, pedestrian/bicyclist crashes, and motorcycle crashes are associated with a higher risk of injury that is less obvious, and yet merits further evaluation at a facility within the trauma system. Step 4 looks for patient characteristics antecedent to the traumatic event that exacerbate the consequences of injury (extremes of age, bleeding diatheses, end-stage renal disease, and pregnancy), isolated limb or eyesight-threatening injuries, and burns. The presence of patient characteristics or characteristic injuries prompts consideration for patient transport to specific centers within a trauma system.

The field triage decision scheme emphasizes the importance of explicitly defining the capabilities of facilities within the system of care and matching the patient to the facility with the most appropriate level of care. An inclusive trauma system brings all local prehospital agencies and acute care facilities together as a network for the focused application of system capabilities to the care of each acutely injured patient. The idea is to get the right patient to the right place within the right time. Underestimation of patient injuries can lead to undertriage to facilities without adequate resources for patient needs, and overestimation of patient injuries can lead to overtriage to facilities with resources far greater than patient needs. Effective triage requires an integrated and defined shared mental model of triage across all settings of care.

MASS CASUALTY TRIAGE

Mass casualty incidents are distinguished from multiple casualty situations by available resources: with mass casualties, resources for each patient are limited, whereas with multiple casualties, full resources can be brought to bear on each individual patient. Mass casualty triage begins with recognition that an event has occurred that has generated casualties exceeding available resources.

Triage in a mass casualty incident seeks to put order into chaos by sifting out noncritically injured casualties in order to find those casualties who need acute attention. Triage begins at the scene, following scene risk assessment and implementation of first responder safety and security measures. The “second-hit” phenomenon, whether by secondary building collapse, chemical contamination, or intentional sequential explosives, is real. Failure to pay attention to scene safety can result in secondary casualties, which can include first responders, and the magnitude of the event increases.

The MASS technique is a useful method for limited first responders to separate acute and nonacute care casualties within a large casualty population: Move, Assess, Sort, Send. First, casualties who can walk are directed to move to an easily identified area with a visible care giver; these are the “walking wounded.” Next, the remaining casualties who cannot walk are instructed to raise an arm or leg, indicating that they have cerebral perfusion and anatomic injuries; these are “delayed” in priority. The remaining casualties then fall into one of three areas: those who require immediate attention, those who have injuries incompatible with survival, and those who are dead. Simple airway, breathing, and circulation assessments are conducted through this population using common field triage instruments to identify the primary casualties who need immediate/acute care.

Triage categories help to prioritize the care of casualties and guide the timing of intervention and evacuation. They include immediate, delayed, minimal, expectant, and dead. Following an intervention, the casualty is reassessed and re-triaged based on the result.

Immediate casualties have emergent, life-threatening consequences of injury and require rapid intervention for primary airway, breathing, and circulation issues. Airway compromise, tension pneumothorax, and uncontrolled external hemorrhage are classic examples in which relatively simple interventions can be life-saving. Delayed casualties have stable major wounds without uncontrolled hemorrhage, and include nonhemorrhagic penetrating torso injuries and long-bone fractures. Minimal casualties have non–life-threatening, nonurgent injuries, such as superficial soft tissue wounds and stress responses. Expectant casualties have injuries that are unsalvageable regardless of circumstances, or that are unsalvageable given resource limitations. Examples include severe head injury and high-percentage body surface area burns. This category has been largely unused in the American experience, and represents a potential siphon of resources in a bona fide mass casualty incident. “Dead” is listed as a triage category to prevent inappropriate use of resuscitation resources. External identifiers include missing body parts, open head wounds, and massive open torso wounds. The reality is that the mechanisms underlying mass casualty incidents carry a high scene mortality.

Triage occurs at every level of care and is designed to prevent missed casualties with life-threatening injuries. Transitions between care settings are ideal opportunities for reassessment and re-triage. At each care location, it is important that there is adequate space for casualty disposition, forward casualty flow without backtracking, separate places for expectant and dead, an identified place with care for minimal casualties, a decontamination area preceding the initial care area, and a control point.

Usually, a facility has a designated triage officer at the control point to make initial casualty disposition. This position should be preassigned in the facility’s mass casualty plan. The essential characteristics of the triage officer are experience within the system, ability to make decisions, and ability to communicate. Although there is oneformal triage officer at point-of-facility entry, it bears emphasizing that across a system of triage, there are many caregivers performing triage, even within a facility.

Sequential triage as casualties move along the care pathway creates an efficient, error-tolerant system that minimizes the consequences of persistent undertriage and overtriage. Overtriage keeps “distracting” casualties within the care pathway and increases the critical mortality rate, a more appropriate measure of casualty population outcome than overall mortality (Figure 2). Adequate documentation is essential for casualty tracking and re-triage. As patients move across care levels, pertinent documentation provides the developing story to the next caregivers in line.

Figure 2 Graphic relation of overtriage to critical mortality rate in 10 terrorist bombing incidents from 1969 to 1995. Linear correlation coefficient (r)=0.92. AMIA, Buenos Aires; BE, Beirut; Bol, Bologna; BP, Birmingham pubs; CA, Cragavon; CC, Cu Chi; GP, Guildford pubs; OB, Old Bailey; OC, Oklahoma City; TL, Tower of London.

(From Frykberg ER: Medical management of disasters and mass casualties from terrorist bombings: how can we cope? J Trauma 53:201–212, 2002.)

COMMENTS

Effective triage is a unifying thread through a functioning trauma system. Systems that perform daily care and train disciplines together provide the best preparation for mass casualty incidents—surge capacity and capability are practiced regularly. The Institute of Medicine’s 2006 Report on The Future of Emergency Care offers a cautionary assessment of the current state of emergency and trauma care in the United States: the current situation of overcrowding, fragmentation, and resource shortages must be replaced with system planning, coordination, and financing, so that the needs of acutely injured patients are met individually and as a population.