Triage Systems

Triage Frameworks for Emergency Nursing Certification

Triage is the systematic sorting of patients to determine priority of care, ensuring that limited emergency department (ED) resources are allocated to those who need them most urgently. Mastery of triage systems is a core competency for the Certified Emergency Nurse (CEN) and is heavily tested on the exam. A structured triage approach reduces under‑triage (missing critical illness) and over‑triage (wasting resources on non‑urgent cases) and directly impacts patient safety and flow.^[1]

The Emergency Severity Index (ESI) is the most widely used triage system in U.S. EDs, endorsed by the Emergency Nurses Association (ENA) and the American College of Emergency Physicians (ACEP).^[2] Understanding the 5‑level ESI algorithm, as well as the START system for mass casualty incidents, is essential for exam success.

ESI Level Classifications and Triage Terminology

Triage – From the French trier (to sort). The process of determining the urgency of a patient’s condition and assigning treatment priority.
ESI Level 1 – Resuscitation – Patient requires immediate life‑saving interventions (e.g., cardiac arrest, severe respiratory distress). No resource prediction needed; these patients are unstable.
ESI Level 2 – Emergent – High‑risk situation (e.g., chest pain with diaphoresis, altered mental status). The patient may be stable now but is in danger of deterioration; often placed in a “fast‑track” resus area.
ESI Level 3 – Urgent – Patient is stable but needs two or more resources (e.g., labs, IV fluids, ECG, X‑ray) AND has abnormal vital signs or a complex chief complaint (e.g., acute abdominal pain).
ESI Level 4 – Less Urgent – Needs one resource (e.g., simple laceration repair, urinalysis). Patient is stable and vital signs are normal.
ESI Level 5 – Non‑Urgent – Needs no resources (e.g., prescription refill, minor sore throat). Patient can wait and be treated in a clinic or fast‑track.
Resource count – In ESI, “resources” include labs, imaging, IV fluids, medications, consultations, or procedures expected within 2 hours. (Counting does not include vital signs, physical exam, basic history, or observation time.)
START – Simple Triage and Rapid Treatment – For mass casualty incidents (MCIs) using a 4‑category system: Immediate (RED), Delayed (YELLOW), Minor (GREEN), and Deceased/Expectant (BLACK).
Triage decision point – The first step in ESI: “Is this patient dying or clearly unstable?” If yes → assign Level 1 or 2; if no → move to resource prediction.^[3]

ESI Algorithm and START Triage Workflow

ESI Algorithm (5‑Level)

Step 1: “Is the patient dying?” – Unambiguous airway, breathing, or circulation compromise? If yes → ESI Level 1 (resuscitation).
Step 2: “Is this a high‑risk situation or new‑onset confusion/pain?” – If the patient appears unstable or has a complaint that could rapidly deteriorate (e.g., chest pain, hemoptysis, anaphylaxis), assign ESI Level 2 even if they are not actively dying.
Step 3: “How many resources will this patient need?” – Predict what tests, treatments, or consultations will be ordered within 2 hours. Count each resource once.
Step 4: “Are vital signs abnormal or is this a high‑risk chief complaint?” – If the patient is stable and needs ≥2 resources, check vital signs. Abnormal vitals (e.g., HR >100, RR >20, SpO₂ <92%, age‑adjusted hypotension) or a “dangerous” mechanism/complaint (e.g., fall in elderly, high‑speed MVC) → ESI Level 3. If vitals normal and no high‑risk criteria → ESI Level 2 (actually level 2? No – careful: For a patient with ≥2 resources and normal vitals, it is **ESI Level 3**; only if the patient is truly high‑risk per Step 2 would it be Level 2. The algorithm rechecks: if vitals are abnormal in a stable patient needing ≥2 resources → Level 3; if vitals are normal → still Level 3 unless the chief complaint is high‑risk (e.g., intractable pain) which then makes them Level 2. See ENA guidelines.)
Step 5: “Fewer than 2 resources?” – Patient needs 1 resource → ESI Level 4; needs 0 resources → ESI Level 5. Vital signs are normal or not required to make this determination.

Note: The ESI algorithm is a two‑branch system: first decide if the patient needs immediate life‑saving intervention (Level 1 or 2), then count resources to assign 3/4/5.^[4]

START Triage (Mass Casualty)

RPM approach – Assess Respirations, Perfusion (capillary refill or radial pulse), and Mental status.
Step 1: Respirations – If no respirations after opening airway → BLACK (deceased). If respirations >30/min → RED (immediate). If respirations normal → move to perfusion.
Step 2: Perfusion – Check radial pulse and/or capillary refill. If absent radial pulse or capillary refill >2 sec → RED. If present → move to mental status.
Step 3: Mental status – If patient can follow simple commands → GREEN (minor). If they cannot follow commands → RED.
Additional: Any patient with uncontrolled hemorrhage or severe burns is often upgraded to RED. Patients with moderate injuries who can eventually walk are YELLOW (delayed).

ENA stresses that all nurses must be able to perform START triage during drills and real disasters.^[5]

Pediatric Triage (JumpSTART)

For children ≤8 years old, use JumpSTART modification: assess respiratory rate; if apneic, give 5 rescue breaths. If still apneic → BLACK; if breathing resumes → RED.
Pediatric normal RR is 15–45/min (age‑dependent); use >45/min as threshold for RED.
Palpable carotid pulse (not radial) is used for perfusion check.^[6]

Clinical Indicators for Triage Severity Assignment

Immediate life‑threat indicators (ESI Level 1): Apnea, cardiac arrest, severe hypotension, massive hemorrhage, unresponsive with no pulse.
High‑risk complaints (ESI Level 2): Chest pain with ST changes, status epilepticus, anaphylaxis, severe respiratory distress, overdose with GCS <9, acute visual disturbance, labor with complications.
Abnormal vital signs that may move a patient to Level 3:
- Adult: HR >100 bpm, RR >20, SpO₂ <92%, SBP <90 or >180, temperature >38.5°C or <35°C.
- Pediatric: Use age‑based tables (e.g., infant HR >180, RR >50).
- Pain scale >7 / 10 (severe) with abnormal vitals often qualifies as Level 2.
“Danger zone” mechanisms: Falls from height >20 ft, high‑speed MVC with ejection or death of another occupant, penetrating trauma to head/chest/abdomen.^[7]

Triage Assessment Parameters and Resource Prediction

Primary survey (A–B–C–D–E) – Always performed within the first 30–60 seconds of triage to identify immediate threats.
Vital signs – Obtain quickly (BP, HR, RR, SpO₂, temperature). Use age‑appropriate norms.
Resource prediction – Based on chief complaint, history, and clinical judgment. Common resources: CBC, CMP, blood culture, ECG, plain X‑ray, CT scan, IV fluids, IV antibiotics, specialty consult.
Inter‑rater reliability – The CEN exam may test that triage nurses must be appropriately trained to avoid both under‑ and over‑triage. ENA recommends annual competency validation.^[8]

Emergency Nursing Interventions by Triage Level

ESI Level 1: immediately place in resuscitation bay, start CPR if needed, attach monitor, call code team, initiate IV/IO access, administer life‑saving drugs per protocol.
ESI Level 2: move to treatment room within 10 minutes, start IV, obtain ECG, apply oxygen, expedite labs/imaging, notify attending physician.
ESI Level 3: place in acute care area, start IV if needed, complete workup in ≤60 minutes, monitor for deterioration.
ESI Level 4: direct to fast‑track or minor care; treat within 1–2 hours.
ESI Level 5: provide self‑care instructions or refer to clinic; wait times may exceed 2 hours.
Mass casualty / MCI: use START tags (RED/YELLOW/GREEN/BLACK) and direct patient flow to respective treatment areas. The triage nurse must constantly re‑triage as patients deteriorate or improve.^[9]

Risk Mitigation and Common Triage Errors

Under‑triage – Assigning a level too low (e.g., Level 3 instead of Level 2). This can delay critical interventions and increase morbidity/mortality.
Over‑triage – Assigning a level too high (e.g., Level 2 instead of Level 4). This wastes resources, increases waiting times for truly urgent patients, and contributes to ED crowding.
ESI resource counting errors: Common mistakes include counting physical exam or vital signs as resources, or counting multiple of the same test (e.g., two CT scans = 1 resource since it’s imaging category). Only one resource per category per patient encounter.
Pediatric pitfalls: Children can compensate until sudden decompensation. Use age‑appropriate vital signs and the JumpSTART algorithm in MCIs. Never use adult vitals for children under 12.
Patient re–evaluation: Any patient with a change in condition (e.g., new chest pain, syncope) must be re‑triaged immediately, even if they were previously Level 4/5.
Ethical and legal considerations: Triage decisions must be based solely on clinical need, not age, race, insurance, or social status.^[10]

CEN Exam Triage Strategies and Memory Aids

Remember the ESI “D” word: Dying → Level 1; Danger zone → Level 2; Determine resources → Level 3/4/5.
Common test questions:
- “Which ESI level for a patient with chest pain, diaphoresis, and BP 80/50?” → Level 1 (unstable).
- “Which level for a 6‑year‑old with respiratory rate 50 and SpO₂ 90%?” → Level 2 (high‑risk, abnormal vitals).
- “START: apneic patient who resumes breathing after airway opening → color?” → RED.
- “What is the maximum number of resources for ESI Level 4?” → 1.
Memory aid for START RPM: “Resps → Perfusion → Mental status” (RPM).
Priority for exam: Triage scenarios appear on every CEN exam. Focus on practical application of the ESI algorithm, START categories, and common pitfalls.
Know that ESI Level 3 is the most common level assigned and the hardest to differentiate. Practice resource counting for typical complaints (e.g., abdominal pain with labs and CT = 2 resources → Level 3).
Pediatric vital sign thresholds: Infants: HR >180, RR >50; School‑age: HR >140, RR >40; Adolescents: same as adult. Memorize age‑based tables for the exam.