Triage is a fundamental medical process used to sort and categorize injured or ill individuals based on the urgency of their need for care. The term originates from the French word trier, meaning “to sort,” and establishes treatment priority when medical resources are limited. While used daily in hospitals, this organizational tool is especially relevant in mass casualty situations where providers are outnumbered by patients. The ultimate goal of any triage system is to maximize the number of survivors by ensuring timely intervention for those who will benefit most.
The Military Origins of Triage
The birth of modern triage occurred during the French Revolutionary and Napoleonic Wars, when battlefield medicine was rudimentary. Previously, army regulations dictated that wounded soldiers were left on the field until the battle concluded and medical wagons could retrieve them. This delay meant many soldiers died from preventable blood loss or shock.
The system was revolutionized around 1792 by Baron Dominique Jean Larrey, Napoleon Bonaparte’s chief surgeon, who developed the ambulance volante, or “flying ambulance.” This innovation used light, horse-drawn carriages to rapidly transport medical staff and supplies directly onto the battlefield. Larrey’s teams provided initial treatment and evacuated the wounded quickly.
Larrey’s most lasting contribution was the formalized method of sorting the wounded for immediate care. He insisted that priority be given to the most severely wounded, regardless of their military rank. This classification, based solely on the severity of the wound, was the initial application of triage principles.
Shifting Triage from Priority to Prognosis
Larrey’s initial concept focused on treating the most severe injuries to prevent rapid death, but the philosophy evolved significantly in later conflicts. The massive casualties of World War I and World War II forced refinement of the sorting process. Triage shifted from prioritizing the most severely injured to prioritizing those with the greatest chance of survival if treated immediately.
This introduced the principle of “the greatest good for the greatest number.” Treatable, life-threatening injuries took precedence over minor wounds or catastrophic injuries unlikely to survive. This approach ensured limited resources were allocated where they could be most effective in saving multiple lives.
This formalization led to the use of color-coding and numerical systems. Triage officers began assessing prognosis and the likelihood of maximizing collective survival. This methodology preserved capacity by ensuring resources were not expended on individuals unlikely to survive.
Triage in Modern Civilian Medicine
The military concept of triage was eventually adapted for civilian medical use, evolving into two distinct applications: routine hospital care and mass casualty incident (MCI) response.
Routine Hospital Care: Emergency Severity Index (ESI)
In the hospital setting, the Emergency Severity Index (ESI) is the most widely adopted system in the United States, used by approximately 94% of Emergency Departments (EDs). The ESI is a five-level scale, with Level 1 indicating the most urgent need for life-saving intervention and Level 5 representing the least urgent.
The ESI is unique in that it incorporates both patient acuity and the prediction of resources needed for their care. For patients who are not immediately life-threatened (Levels 3, 4, and 5), the triage nurse assesses how many resources, such as laboratory tests, X-rays, or specialized consultations, the patient is likely to consume. This resource-based component helps manage patient flow and waiting times, distinguishing it from systems used in resource-scarce disaster environments.
Mass Casualty Incidents: START
For mass casualty incidents, like natural disasters or large accidents, a simpler, faster system is required. The most common is Simple Triage and Rapid Treatment (START), developed in 1983. START allows first responders to rapidly classify victims in 30 seconds or less using a four-category color-code: Red (Immediate), Yellow (Delayed), Green (Minor/Ambulatory), and Black (Deceased/Expectant).
The START system relies on assessing three physiological parameters: Respiration, Perfusion, and Mental Status (RPM). For instance, a patient with a respiratory rate over 30 breaths per minute or who cannot follow simple commands is immediately tagged Red, indicating a need for urgent attention. START is an expedient method designed to be performed by minimally trained personnel to quickly sort patients for transport and is not intended to determine definitive resource allocation.