Triage in Healthcare: Process, Colors & Scales

In emergency medicine, the most precious commodities are time and resources. Triage is the non-negotiable process that manages both. This front-line assessment method is designed to rapidly determine the severity of a patient’s illness or injury. 

This guide will delve beyond the surface, exploring the methodologies of triage from chaotic pre-hospital scenarios to the structured environment of a hospital Emergency Department.

What is Triage in Healthcare?

Triage (pronounced tree-ahj), from the French word meaning “to sort,” is a critical process in healthcare designed to ration limited resources by prioritizing patients based on the severity of their condition and their likelihood of benefiting from immediate care. 

The core objective of triage is not merely to determine who is “sickest,” but to identify patients whose conditions are time-critical and pose an immediate threat to life or limb.

Triage in the Pre-Hospital and Mass Casualty Setting (MCI)

In situations of high demand, such as natural disasters, military conflicts, or major accidents (Mass Casualty Incidents or MCIs), field triage uses simple, rapid protocols to maximize the number of survivors based on the best practices for Secure Triage and departmental communication

The S.T.A.R.T. Protocol (Simple Triage and Rapid Treatment)

The S.T.A.R.T. The method is a rapid, 30-60 second assessment that classifies patients based on respirations, perfusion, and mental status (RPM). This leads to the assignment of one of four color tags:

Red (Immediate / P-1):

• Meaning: Life-threatening injuries requiring immediate transport and intervention for survival.
• Criteria: Absent/inadequate respirations (after repositioning), Capillary Refill >2 seconds, OR inability to follow simple commands.

Yellow (Delayed / P-2):

• Meaning: Serious injuries needing medical attention within hours; stable enough to wait.
• Criteria: Adequate respirations, Capillary Refill <2 seconds, AND follows simple commands.

Green (Minor / P-3):

• Meaning: “Walking Wounded”; minor injuries, often self-care or minimal intervention needed.
• Criteria: Can walk away from the scene; often treated and released.

Black (Expectant/Deceased):

• Meaning: Deceased, or injuries so severe that survival is highly unlikely given available resources.
• Criteria: Absent respirations (even after repositioning).

Triage in the Hospital Emergency Department (ED)

In the Emergency Department, triage focuses on clinical acuity, pain management, and efficient patient flow within a controlled environment. The goal shifts from mass survival to individualized care and resource allocation.

Standardized Acuity Scales

EDs use validated, multi-level scales to assign patients a numerical acuity score. These standards improve reliability and inter-rater consistency.

1. Emergency Severity Index (ESI) – Most Common in the U.S.

The ESI is a five-level triage system based on two main criteria: prediction of resource utilization and stability/life threat.

Level 1 (Resuscitation)

• Immediate Life-Saving Intervention? YES. Patient is dying or about to die.
• Risk & Time: High risk; seen Immediately by a physician.

Level 2 (Emergent)

• Immediate Life-Saving Intervention? NO, but high risk of deterioration or severe pain/distress.
• Risk & Time: Needs to be seen within 10 minutes.

Level 3 (Urgent):

• Immediate Life-Saving Intervention? NO. Stable, but requires multiple resources (e.g., labs, X-ray, IV fluids).
• Risk & Time: Needs to be seen within 30-60 minutes.

Level 4 (Less Urgent):

• Immediate Life-Saving Intervention? NO. Requires only one resource (e.g., simple prescription, history/physical exam).
• Risk & Time: Wait time variable.

Level 5 (Non-Urgent):

• Immediate Life-Saving Intervention? NO. Requires no resources.
• Risk & Time: Wait time longest.

Canadian Triage and Acuity Scale (CTAS)

Similar to ESI, the CTAS is a five-level scale focusing on time-to-physician-assessment targets and incorporates more factors related to presenting complaints (e.g., severity of pain, type of injury).

The Indepth ED Triage Assessment

The specialized ED triage nurse must conduct a comprehensive, yet fast, evaluation:

Immediate Visual Scan

Look for obvious signs of distress, hemorrhage, or altered mental status (the “eyeball test”).

Chief Complaint & Focused History

Determine the reason for the visit and elicit key symptoms (e.g., onset, duration, quality of pain).

Core Vitals

Obtain full vital signs, including Blood Pressure, Heart Rate, Respiratory Rate, Oxygen Saturation, Temperature, and Pain Score (using a standardized scale).

“Red Flag” Identification

Screening for critical indicators like signs of sepsis, stroke (FAST), acute coronary syndrome (chest pain), and major trauma.

Intervention Initiation

In high-acuity cases (ESI 1 or 2), the triage nurse may initiate standing orders (e.g., starting an IV, administering aspirin for chest pain, or ordering a rapid EKG) before the patient sees a physician. This is called Nurse-Initiated Protocols and is a cornerstone of modern ED efficiency.

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Reassessment and Flow Management

Triage is a dynamic process. Patients can deteriorate rapidly in the waiting room, turning an ESI 3 into an ESI 1.

Reassessment/Re-triage

Triage nurses must continuously monitor the waiting area, especially for those with high-risk complaints or the elderly. 

Re-triage is performed periodically, and any signs of deterioration (e.g., new shortness of breath, sudden drop in consciousness, increased bleeding) necessitate an immediate upgrade of the triage level.

Flow Management

Triage data is essential for the Charge Nurse to manage hospital flow. It dictates bed assignments, staffing levels, and where the next available provider should be focused.

In times of overcrowding, the triage data justifies critical decisions, including Ambulance Diversion (redirecting ambulances to less-crowded hospitals) to maintain safe patient care capacity.

Conclusion: Triage as a Quality & Safety Imperative

Triage systems are vital for efficient patient flow management, especially during high-demand periods like pandemics or major accidents. Effective, reliable, and consistent triage is important for mitigating risk, and upholding the ethical commitment to provide timely care to those with the greatest need. 

Triage excellence is foundational to the trustworthiness of any emergency healthcare system.