Free tool · Triage algorithm · ER
ESI Triage — Emergency Severity Index.
A plain-language walk through the five-level ED triage approach, one decision at a time. Work the A–D decision points and land on an acuity level (1 = needs an immediate life-saving intervention, down to 5 = no resources expected). We've written this in our own words and it only captures the decision flow — for the authoritative criteria, the full resource definitions, and the age-specific vital-sign danger zones, use the official materials hosted by AHRQ (current edition maintained by the ENA). Triage is a clinical judgment — the level supports it, it doesn't replace it.
Walk the decision points
Work top to bottom; the tool stops as soon as the algorithm reaches a level.
What counts as a resource?
Counts (1 each)
- Labs (blood, urine)
- ECG, X-ray, CT, MRI, ultrasound
- IV fluids (hydration)
- IV / IM / nebulized medications
- Specialty consult
- Simple procedure = 1 (e.g. laceration repair, Foley); complex = 2 (e.g. conscious sedation)
Does not count
- History & physical / exam
- Point-of-care testing
- Saline or heparin lock (placement)
- PO medications
- Prescription refill
- Phone call to PCP
- Simple wound care, splint, sling, crutches
- Tetanus immunization
These are common examples of what does and doesn't count as a resource, described in our own words and consistent with the publicly available AHRQ ESI materials. For the authoritative current list, use the official AHRQ/ENA materials.
Answer the decision points to see the ESI level.
The five levels [1]
| Level | Meaning | Reached when |
|---|---|---|
| 1 | Resuscitation | A = Yes (immediate life-saving intervention) |
| 2 | Emergent | B = Yes (high-risk / altered / severe distress), or up-triaged from D |
| 3 | Urgent | 2+ resources, vitals not in danger zone |
| 4 | Less urgent | 1 resource |
| 5 | Nonurgent | 0 resources |
The algorithm flows A → B → C → D. A "Yes" at A makes it Level 1; a "Yes" at B makes it Level 2; otherwise the resource count (C) sets 5 / 4 / 3, and at Level 3 the vital-sign check (D) can up-triage to Level 2.[1] Exact resource definitions and age-specific danger-zone vitals live in the handbook.
References
- Agency for Healthcare Research and Quality (AHRQ). Emergency Severity Index (ESI): A Triage Tool for Emergency Department Care. ahrq.gov/patient-safety/settings/emergency-dept/esi.html. (Publicly available implementation materials describing the five-level A–D triage approach and resource concept.)
- Emergency Nurses Association (ENA). Emergency Severity Index (ESI) Implementation Handbook (current edition). ena.org. (The current edition is maintained and copyrighted by the ENA; consult it for the authoritative, full criteria — referenced here only.)
This walkthrough was written in our own words to capture the A–D decision flow and the level meanings; the detailed criteria, exact resource list, and danger-zone vital signs belong to the official materials — start with the free AHRQ ESI page. ESI® is a registered trademark of the ENA; BrainSheets is not affiliated with or endorsed by the ENA. Your ED's triage protocol takes precedence.