What is the field triage decision scheme?

Field Triage Decision Scheme

The Field Triage Decision Scheme is a four-step algorithmic tool developed by the American College of Surgeons that guides EMS providers through sequential evaluation of physiologic criteria, anatomic injury patterns, mechanism of injury, and special patient considerations to determine whether injured patients require transport to a trauma center versus a standard emergency department. 1

Purpose and Impact on Mortality

• The Decision Scheme serves as the foundational template for field triage protocols across the majority of EMS systems in the United States, enabling EMS providers to identify patients at greatest risk for severe injury and match them to appropriate facility capabilities. 1

• Transport to a Level I trauma center reduces mortality by 25% for severely injured patients compared to non-trauma facilities. 1

• The scheme balances two competing priorities: avoiding under-triage (missing seriously injured patients who need trauma center resources) while preventing over-triage (overwhelming trauma centers with patients who could be managed at closer facilities). 1

The Four Sequential Decision Steps

The algorithm guides providers through four hierarchical steps, with any positive finding at any step indicating trauma center transport: 1

Step 1: Physiologic Criteria

• Evaluates vital signs and level of consciousness as immediate indicators of physiologic compromise
• Includes Glasgow Coma Scale score, systolic blood pressure, and respiratory rate 1

Step 2: Anatomic Criteria

• Assesses specific injury patterns known to correlate with severe trauma
• Includes penetrating injuries to specific body regions, flail chest, multiple proximal long bone fractures, crushed/degloved/mangled extremities, amputation proximal to wrist/ankle, pelvic fractures, open/depressed skull fractures, and paralysis 1

Step 3: Mechanism of Injury

• Considers the forces involved in the traumatic event as predictors of occult injury
• Includes falls, high-speed motor vehicle crashes, vehicle intrusion, ejection, death of another occupant, and pedestrian/cyclist impacts 1

Step 4: Special Patient Considerations

• Accounts for patient factors that increase vulnerability to poor outcomes
• Includes extremes of age (children and older adults), anticoagulation therapy, pregnancy, and EMS provider judgment 1

Evolution and Endorsement

• Originally published in 1986, the scheme has undergone four major revisions (1990,1993,1999, and 2006) to incorporate evolving evidence. 1

• The 2006 revision was developed through the National Expert Panel on Field Triage, convened by CDC with NHTSA support, including injury-care providers, public health professionals, and federal agency representatives. 1

• The guidelines have been endorsed by over 20 major organizations including the American College of Surgeons, American College of Emergency Physicians, American Academy of Pediatrics, and National Association of EMS Physicians. 1

Trauma Center Classification Context

Understanding the destination options is critical for applying the scheme: 1

• Level I centers provide the highest level of trauma care with 24-hour availability of all surgical subspecialties, continuous operating room access, and research/prevention programs
• Level II centers offer similar immediate resources but may lack certain subspecialties or research infrastructure
• Level III centers provide initial stabilization and emergency surgery with transfer capability to higher-level facilities
• Level IV centers offer initial trauma evaluation and stabilization in rural areas with transfer protocols 1

Critical Implementation Challenges

Research reveals significant gaps between the theoretical scheme and real-world application: 2, 3

• EMS providers emphasize speed over systematic application, relying on initial impressions rather than precise vital sign measurement or methodical progression through all four steps. 2

• Prospective validation studies demonstrate the guidelines have only 66.2% sensitivity for identifying patients with Injury Severity Score ≥16, falling well short of the target of under-triaging less than 5% of seriously injured patients. 3

• Sensitivity decreases dramatically with age, from 87.4% in children to only 51.8% in older adults, indicating the scheme performs poorly in geriatric trauma. 3

• Under-triage rates range from 1.6% to 72.0% depending on patient age and whether the scheme is applied strictly versus as-practiced, with particularly high rates (20.1-72.0%) in older adults. 4

• Over-triage rates range from 9.9% to 87.4%, often exceeding the target range of 25-35%. 4

Local Adaptation

• Individual EMS systems may modify the Decision Scheme to reflect their operational context, including urban versus rural environments, availability of specialized pediatric trauma centers, and local medical director discretion. 1

• Despite local variations, the core four-step structure remains the national standard for field trauma triage decision-making. 1