Triage (from the French "to sort") is the rapid sorting of clients by urgency so that the sickest receive care first and resources go where they help most. The key question is always: is there a threat to life, limb, or organ, and how soon will this person deteriorate? The intensity of pain, time of onset, or order of arrival are secondary.

Triage works differently in two settings:

Principles common to both

• Triage is a rapid, focused assessment, not a full examination (ESI initial assessment usually takes a few minutes; START about 30–60 seconds per casualty).
• ABCs and mental status drive decisions: airway, breathing, circulation, disability.
• Re-triage is continuous — a client's condition can worsen while waiting; acuity can be raised at any time.
• Under-triage (assigning too low a priority) endangers the client; over-triage wastes scarce resources, especially in an MCI. Older adults, clients on beta blockers or steroids, and people affected by bias are at higher risk of under-triage.

Across-the-room look (first seconds): general appearance, work of breathing, skin color, level of consciousness, obvious bleeding.

Focused triage assessment

• Chief complaint and brief history (onset, allergies, medications, relevant history)
• Airway patency, respiratory rate and effort, SpO₂
• Heart rate, blood pressure, skin temperature, capillary refill
• Mental status using AVPU (Alert, responds to Voice, responds to Pain, Unresponsive) or GCS
• Pain score, temperature, and in children, weight and immunization status
• Vital signs must be interpreted in context: beta blockers can hide tachycardia; steroids and older age can blunt fever

Findings that signal high risk (ESI level 2)

• Chest pain suspicious for acute coronary syndrome but not needing an immediate lifesaving intervention
• Signs of stroke; sudden severe ("thunderclap") headache; headache with fever, neck stiffness, or altered mental status
• New confusion, lethargy, or disorientation
• Severe pain or distress from a systemic cause (renal colic, sickle cell crisis)
• Suspected sepsis, fever in immunocompromised clients (chemotherapy, transplant)
• Suicidal or homicidal ideation; possible ectopic pregnancy; neurovascular compromise of a limb

ESI algorithm (version 5, 2023) — decision points are used in order.

ESI 1 presentations: intubated, unresponsive, pulseless, apneic, severe respiratory distress, profound hypotension, hypoglycemia, flaccid infant. Unresponsive means acutely nonverbal and not following commands, or responding only to pain or not at all (P or U on AVPU).

High-risk vital signs for adults (older than 18 years): HR > 100/min, RR > 20/min, SpO₂ < 92%. Pediatric thresholds are higher and age-based (for example, HR > 190 and RR > 60 under 1 month). In version 5, vital signs are reviewed before finalizing levels 3, 4, and 5, not only level 3.

What counts as a resource

A CBC plus electrolytes is one resource (both labs); a CBC plus a chest radiograph is two.

Pediatric fever

• 1–28 days with temperature > 38.0°C (100.4°F): at least ESI 2
• 1–3 months with temperature > 38.0°C: consider ESI 2
• 3 months and older: consider ESI 2 or 3 if temperature > 39°C (102.2°F) or < 36°C (96.8°F), incomplete immunizations, or no obvious source

Worked examples

Mass casualty triage

START (adults) — assesses walking, breathing, respiratory rate, perfusion, and mental status:

1. Can walk? → Green (minor), direct to a collection point.
2. Not breathing? → reposition the airway. Still not breathing → Black (expectant/deceased). Breathes after repositioning → Red (immediate).
3. Respiratory rate > 30/min → Red.
4. No radial pulse or capillary refill > 2 seconds → Red (control bleeding).
5. Cannot follow simple commands → Red.
6. Otherwise → Yellow (delayed).

JumpSTART (children, about 1–8 years): if not breathing but a pulse is present, give 5 rescue breaths before tagging; RR < 15 or > 45 → Red; absent peripheral pulse → Red; inappropriate response to pain or unresponsive on AVPU → Red.

SALT (Sort, Assess, Lifesaving interventions, Treatment/Transport):

• Global sort: those who are still or have obvious life threats are assessed first, those who wave or move purposefully second, those who walk last
• Lifesaving interventions (only if quick and within scope): control major hemorrhage, open the airway (2 rescue breaths in children), chest decompression, autoinjector antidotes
• Individual assessment: obeys commands or makes purposeful movements, has a peripheral pulse, no respiratory distress, major bleeding controlled → Yellow or Green; any "no" → Red unless unlikely to survive with current resources → Gray (expectant); not breathing → Black (dead)

Triage categories and colors

Expectant clients receive comfort measures and are re-triaged as resources become available. In hospitals during a surge, secondary triage is repeated at arrival and reverse triage discharges stable inpatients to make room.

Listed in priority order.

1. Ensure safety — scene safety in the field; in the ED, standard precautions and isolation of clients with possible airborne infection (fever with rash, cough with suspected tuberculosis or measles)
2. Recognize and act on life threats immediately — move ESI 1 clients straight to resuscitation; do not delay care to finish vital signs; in an MCI, perform only brief lifesaving interventions (tourniquet, airway positioning) and move on
3. Assign the acuity level using the facility's tool; use the highest level that applies
4. Initiate protocols within scope — ECG within 10 minutes for suspected acute coronary syndrome, stroke alert, sepsis screen, ice and elevation for injuries, analgesia per standing orders
5. Reassess waiting clients at set intervals and whenever condition changes; raise acuity if worse; do not downgrade because of crowding or staffing — acuity should reflect current risk
6. Document time, findings, acuity, and interventions; attach triage tags in an MCI
7. Communicate — clear handoff to the treating team; keep clients and families informed of expected waits and when to alert staff

• Explain that clients are seen by how urgent their condition is, not by arrival order
• Tell waiting clients and families to report immediately any new chest pain, breathing difficulty, fainting, confusion, worsening pain, or bleeding
• Do not eat or drink until assessed if surgery or sedation may be needed, unless staff say otherwise
• In a disaster, follow instructions of responders; people who can walk help keep treatment areas clear for the critically injured
• For non-urgent problems, use primary care or urgent care when appropriate, but never delay care for emergency warning signs

• Core question: threat to life, limb, or organ? — not pain score or arrival order
• ESI: A lifesaving intervention → 1; B high risk, confused/lethargic, severe pain → 2; C resources 2+ → 3, one → 4, none → 5; D high-risk vitals → consider upgrade
• Adult high-risk vitals: HR > 100, RR > 20, SpO₂ < 92%
• Count types of resources; oral meds, splints, crutches, saline lock, tetanus shot are not resources
• Febrile infant ≤ 28 days (> 38.0°C) = at least ESI 2
• START: walking → Green; RR > 30, no radial pulse or capillary refill > 2 s, cannot follow commands → Red; otherwise Yellow; not breathing after airway repositioning → Black
• JumpSTART: 5 rescue breaths if pulse present; RR < 15 or > 45 → Red
• SALT: sort (still → wave → walk), 4 lifesaving interventions, Gray = expectant, Black = dead
• Red immediate, Yellow delayed, Green minor, Black expectant/dead
• MCI goal: greatest good for the greatest number; re-triage often