Residency · Residency · Emergency Medicine
Mass Casualty Incident Triage and Disaster Response
Introduction
A mass casualty incident (MCI) occurs when the number of patients exceeds the available resources of the responding healthcare system. Effective disaster response requires a fundamental shift from individual patient-centered care to population-based care. Emergency physicians must be proficient in triage systems, incident command structures, and surge capacity planning to lead during these high-stakes events.
Incident Command System (ICS)
Structure and Roles
The Incident Commander holds overall authority for the response; in hospital-based events, this is typically the senior emergency physician or designated administrator. The Operations Section directs tactical activities including patient care areas, triage, and treatment zones. The Planning Section collects and evaluates situational information and develops action plans. The Logistics Section manages resources, supplies, staffing, and equipment. The Finance/Administration Section tracks costs, personnel time, and procurement.
Hospital Incident Command System (HICS)
The Hospital Emergency Operations Plan (EOP) must be activated rapidly, and pre-designated roles reduce confusion. Surge capacity involves expanding bed availability through early discharges, canceling elective procedures, and converting non-clinical spaces. Staff call-back protocols and credentialing of volunteer providers are essential components.
<image>Organizational chart of the Hospital Incident Command System showing the hierarchy from Incident Commander through Operations, Planning, Logistics, and Finance sections with ED-specific roles highlighted</image>
Field Triage Systems
START Triage (Simple Triage and Rapid Treatment)
START triage is designed for first responders and categorizes patients in under 60 seconds each. The assessment sequence evaluates ability to walk, then respiratory status, then perfusion (radial pulse or capillary refill), and finally mental status (ability to follow commands). Patients are categorized as Green (Minor, ambulatory "walking wounded"), Yellow (Delayed, non-ambulatory but stable and able to tolerate delay in treatment), Red (Immediate, life-threatening conditions amenable to rapid intervention), or Black (Expectant/Deceased, dead or with injuries incompatible with survival given available resources).
| Category | Color | Criteria | Priority | Action |
|---|---|---|---|---|
| Minor | Green | Ambulatory ("walking wounded") | Lowest | Delayed treatment acceptable |
| Delayed | Yellow | Non-ambulatory but stable; RR < 30, pulse present, follows commands | Second | Can tolerate treatment delay |
| Immediate | Red | Life-threatening but salvageable; RR > 30, no pulse/cap refill > 2 sec, or not following commands | Highest | Immediate intervention |
| Expectant/Dead | Black | Dead or non-survivable injuries | None | No treatment with current resources |
JumpSTART Triage
JumpSTART is the pediatric modification of START for children ages 1 to 8. It accounts for developmental differences, recognizing that children who are not walking may still be categorized as Yellow. It includes a trial of 5 rescue breaths for apneic children with a pulse before assigning a Black category.
SALT Triage (Sort, Assess, Lifesaving Interventions, Treatment/Transport)
SALT is the CDC-recommended national guideline that integrates elements of multiple systems. It adds a lifesaving interventions step that includes hemorrhage control, airway opening, chest decompression, and auto-injector administration. It introduces an Expectant category as distinct from Dead, identifying patients who are alive but unlikely to survive given current resources.
Secondary (Medical) Triage
Secondary triage is performed at the hospital entrance or treatment area by physicians. It re-evaluates field triage assignments with dynamic reassignment based on clinical trajectory. Tools include SALT re-triage and the Sacco Triage Method, which is evidence-based and uses physiologic scoring.
<image>Side-by-side comparison diagram of START and SALT triage algorithms showing decision points, color categories, and key differences in assessment steps</image>
Types of Disasters
Natural Disasters
Earthquakes produce crush injuries, rhabdomyolysis, and compartment syndrome, with delayed renal failure from myoglobinuria. Hurricanes and floods lead to wound infections, waterborne illness, and displacement-related chronic disease exacerbation. Pandemics require surge planning, PPE allocation, ventilator triage, and ethical allocation frameworks.
Human-Caused Disasters
Active shooter and mass violence events prioritize hemorrhage control using TECC (Tactical Emergency Casualty Care) principles with a tourniquet-first approach. Chemical exposures (HAZMAT) require decontamination before treatment; nerve agents (organophosphates) require atropine plus pralidoxime, and provider safety must be maintained. Radiological and nuclear events may produce acute radiation syndrome, and potassium iodide provides thyroid protection with dose-dependent triage. Biological agents including anthrax, smallpox, plague, and botulism require a high index of suspicion from epidemiologic patterns and public health notification.
Decontamination
Gross decontamination involves removing clothing (which removes approximately 80 percent of the contaminant) and copious water irrigation. Technical decontamination includes soap and water scrub and specific antidotes as indicated. The decontamination corridor is established upwind and uphill from the incident, and runoff must be contained. Provider safety requires appropriate PPE (Level A through D) based on the agent, with SCBA for unknown exposures.
Crisis Standards of Care
When resources are overwhelmed, crisis standards shift the goal from individual optimization to the greatest good for the greatest number. Ventilator allocation frameworks use objective criteria such as SOFA scores and comorbidity assessments to guide resource distribution. Ethical principles include fairness, transparency, proportionality, and accountability, while avoiding allocation based on social worth or ability to pay. Palliative care integration is essential for patients triaged to the expectant category.
<image>Diagram of a hospital decontamination corridor layout showing zones of contamination (hot, warm, cold), patient flow direction, and PPE requirements for providers at each stage</image>
Communication and Coordination
Unified command is used when multiple agencies (fire, EMS, law enforcement, hospital) share jurisdiction. Medical Emergency Radio Communications (MERCI) and dedicated disaster frequencies prevent channel overload. Patient tracking systems such as Salamander and EMTrack use barcoded triage tags to monitor patient location and status. The Public Information Officer (PIO) manages media and public communication to prevent misinformation.
After-Action Review
A hot debrief immediately following the event captures time-sensitive observations. A formal after-action report (AAR) identifies strengths, areas for improvement, and corrective actions. Psychological support for providers includes Critical Incident Stress Management (CISM), peer support, and access to mental health resources.
Clinical Pearls
In an MCI, doing the greatest good for the greatest number replaces individual patient optimization -- this is the hardest cognitive shift for emergency physicians. START triage can categorize a patient in under 60 seconds, and perfection is the enemy of speed in field triage. Decontamination must occur before patients enter the ED, as a contaminated patient in the department can shut down the entire hospital. Crisis standards of care should be pre-established, ethically vetted, and legally supported before a disaster occurs. Regular disaster drills with multidisciplinary participation and honest after-action review are the foundation of preparedness.
References
- Cone DC, Koenig KL. "Mass Casualty Triage in the Chemical, Biological, Radiological, or Nuclear Environment." European Journal of Emergency Medicine. 2005;12(6):287-302.
- Lerner EB, et al. "Mass Casualty Triage: An Evaluation of the Science and Refinement of a National Guideline." Disaster Medicine and Public Health Preparedness. 2011;5(2):129-137.
- Christian MD, et al. "Development of a Triage Protocol for Critical Care During an Influenza Pandemic." CMAJ. 2006;175(11):1377-1381.
- FEMA. National Incident Management System (NIMS). 3rd ed. Washington, DC: Department of Homeland Security; 2017.
