ED Triage and ESI

In depth

The one-page summary above is what the PDF prints. These sections go further.

How ESI sorts patients and what v5 changed

ESI asks two questions in order: is the patient unstable or at high risk now (levels 1–2), and, for stable patients only, how many types of resources will a disposition take (levels 3–5)? Wuerz and Eitel built it in 1998; ENA has owned it since 2019 and released v5 in 2023, and about 94% of US EDs use it (Worth 2019, cited in v5). Unlike the Canadian, Australasian and Manchester scales, ESI sets no time-to-clinician target for any level (v5 Ch. 1). Levels are ordinal: report a distribution, never an average, and never use them for billing (v5 Appendix A).

• Point A: 'unresponsive' is defined; epinephrine (including IM for anaphylaxis) joined the lifesaving list and intraosseous access left it; SpO₂ <90% signals ESI 1 only when it is not the patient's norm and comes with respiratory compromise.
• Point B: 'Is this a patient who shouldn't wait?' and the 'last open bed' test are gone, so the level reflects the patient, not bed availability.
• Point D: full vital signs for every patient who is not ESI 1–2; v4 checked danger-zone vitals only when 2 or more resources were predicted.
• Children: six pediatric age bands, adult HR and RR cutoffs from age 12 instead of 8, and a fever rule that runs past age 3, allows ESI 2 and adds T <36 °C.

Decision point A: lifesaving intervention now

Point A asks whether the patient needs an intervention within minutes to secure the airway, support breathing or circulation, or reverse a major change in consciousness: unresponsiveness, active seizure, an occluded airway, failing gas exchange or failing perfusion (v5 Ch. 3). Unresponsive means acutely nonverbal and not following commands, or needing a painful stimulus (P or U on AVPU). Decide from the doorway and move the patient; the resuscitation team takes vital signs if they would delay care.

Worked examples. Found down, RR 6, pinpoint pupils, needs naloxone and bag-mask breaths: ESI 1, even if he goes home in 4 hours; disposition does not set acuity (v5). Chest pain, SBP 80, cool mottled skin: ESI 1. New facial droop, GCS 15, patent airway: ESI 2; the CT is diagnostic, and a stroke alert does not need ESI 1. COPD at a known SpO₂ of 88–90%, speaking in full sentences: not ESI 1; the same number when new, with accessory muscle use, is.

Decision point B: high risk, new confusion, severe pain or distress

Point B is where triage most often fails: nurses matched the reference level at the ESI 2/3 boundary only about 41–43% of the time (Ivanov 2021, cited in v5). Ask whether the situation threatens life, limb, sight or organ or is time-sensitive, whether the patient is likely to deteriorate, whether mental status is newly altered, and whether pain or distress is severe. v5 dropped the bed-availability questions because nurses had been leveling to ED capacity rather than physiology (v5 preface; Wolf 2018).

Pain of 7/10 or more means consider ESI 2, not assign it; v5 calls this an often-misread criterion. Accept the score, treat it at triage and ask what is causing it: severe pain from renal colic, sickle cell crisis or cancer is ESI 2; an isolated ankle injury with intact pulses and sensation gets ice, elevation and standing-order analgesia and is leveled by resources. Severe psychological distress also qualifies: after sexual assault or domestic violence, in acute grief or pregnancy loss, or with behavioral outbursts (v5).

New confusion, lethargy or disorientation is ESI 2; if the baseline is unknown, assume it is new (v5). A patient with known seizures who is now alert and oriented is leveled by physiology and resources; a post-ictal patient is ESI 2.

Decision point C: predicting resources

Point C applies only after A and B are ruled out. Predict what a typical ED would use to reach a disposition for this presentation, not what one provider tends to order; teaching and community hospitals should count the same (v5 Ch. 5). A resource takes people or equipment beyond routine bedside nursing, which is why v4 counted MRI, a psychiatry consult and a one-to-one observer but not a cardiac monitor.

Worked examples. Can't bear weight after an ankle twist: one film, ESI 4. Forearm laceration needing sutures and a tetanus booster: one simple procedure, ESI 4; add a film for glass and it is ESI 3. Vomiting and RLQ pain: labs, IV fluids and CT, ESI 3. Sore throat with a strep test sent to the lab: ESI 4; a bedside rapid test and an oral prescription: ESI 5.

Decision point D: high-risk vital signs

Every patient who is not ESI 1 or 2 gets a full set of vital signs before the level is final, to find the well-appearing ill (v5 Ch. 6). The algorithm lists heart rate, respiratory rate and SpO₂ <92% (when respiratory compromise is possible), but v5 asks you to reassess any vital sign outside the patient's normal, blood pressure and temperature included. Of 551 patients moved from ESI 3 to 2 in an Iranian ED, 88.7% had a high respiratory rate and 97.8% a high respiratory or heart rate (Nejad 2016, cited in v5).

A value over the line means reassess, not automatic ESI 2: recheck it, read it in context, and up-triage if it stays out of range (v5). β-blockers blunt tachycardia and steroids blunt fever, so normal numbers do not clear a worrying story; one marginal value that settles on recheck does not raise the level. A heart rate of 32 or 180 is ESI 1 however well the patient looks (v5).

Children: first look, vital signs and fever

Start with the pediatric assessment triangle from the doorway: appearance (tone, interactiveness, consolability, gaze, cry), work of breathing (retractions, grunting, flaring, head bobbing, noisy breathing) and circulation to the skin (pallor, mottling, cyanosis); any abnormal side sends you to point A or B before the history. Then take full vital signs, counting an infant's respiratory rate for a whole minute. Hypotension is late: systolic under 60 mm Hg in term neonates, under 70 in infants, under 70 + 2 × age in years from 1 to 10, and under 90 after 10 (PALS).

v5 is inconsistent on fever. Its algorithm gives at least ESI 2 for T >38 °C (100.4 °F) at 28 days or younger, consider ESI 2 at 1–3 months, and consider ESI 2 or 3 after 3 months for T >39 °C or <36 °C, incomplete immunizations or no obvious source; Chapter 6 says at least ESI 2 for T >38 °C under 90 days and uses >38.5 °C after 3 months. Below 36 °C is a sepsis flag at any age. A clear source with up-to-date immunizations allows ESI 4 or 5.

Other red flags: a subtle drop in interaction, grunting or belly breathing, a flaccid infant (ESI 1), and a swallowed button battery, worst under age 6 and over 20 mm (v5). Fever with a non-petechial rash and incomplete immunizations should prompt isolation; a child alert and acting normally after a febrile seizure is leveled by physiology and resources.

Children are harder to level: agreement fell from κ 0.77 on written cases to 0.57 on real patients, with more under-triage in general than pediatric EDs (Travers 2009), and nurses matched 46.9% of pediatric versus 66.2% of adult scenarios (Mistry 2018). Black, Hispanic and American Indian children received lower-acuity scores than White children after adjustment (Zook 2016).

Presentations that get under-triaged

Under-triage clusters where illness does not look like the textbook. In older adults, ESI 1 caught 46% (Grossmann 2012) and 42% (Platts-Mills 2010) of those who needed a lifesaving intervention; Grossmann traced most under-triage to overlooked high-risk situations and misread vital signs. In 21 community EDs, 39% of patients with subarachnoid hemorrhage, 30% with aortic dissection and 16% with STEMI were triaged ESI 3, and under-triaged patients waited 33 minutes longer for antihypertensives in hemorrhage and 18 minutes longer for β-blockers in dissection (Sax 2025).

Older adults: IDSA 2008 fever criteria for long-term care residents start at a single oral temperature >37.8 °C (100 °F) or a rise >1.1 °C (2 °F) over baseline, and the 2021 field triage guideline treats SBP <110 mm Hg as a red flag in injured adults 65 and older.

Atypical ACS: a third of 434,877 MI patients had no chest pain; they were older, more often women or diabetic, and died in hospital at 23.3% versus 9.3% (Canto 2000). Women lacked chest pain more often than men, 42.0% versus 30.7% (Canto 2012). Get an ECG within 10 minutes for chest pain or an anginal equivalent (AHA/ACC 2021).

Sepsis: ESI has no sepsis screen; it catches sepsis at point B (fever with immunosuppression, rigors and flank pain in an older adult) and point D. SSC 2021 advises against qSOFA as a single screening tool, and each hour to antibiotics carried about 4% higher odds of death (Seymour 2017).

Stroke: FAST missed 14.1% of ischemic strokes and BE-FAST, which adds balance and eyes, 4.4% (Aroor 2017), and 37% of posterior versus 16% of anterior strokes were missed at first, often presenting as dizziness or vomiting (Arch 2016). Mimics run the other way (hypoglycemia, post-ictal deficits, migraine aura, sepsis): check a fingerstick glucose, record last known well, and keep a deficit at ESI 2 until a clinician excludes stroke; hypoglycemia needing IV dextrose is ESI 1.

Behavioral health and violence risk

Behavioral health visits are more than 12% of US ED visits (Moore 2017, cited in v5). Suicidal, homicidal, psychotic or violent patients are ESI 2 (v4 also named elopement risk), as is severe psychological distress; ESI 1 requires a lifesaving need, such as an overdose with apnea. A calm patient with no safety risk is leveled by resources: a behavioral health evaluation counts as a specialty consultation (v4 FAQ), so evaluation alone is ESI 4 and evaluation plus labs ESI 3.

Screening: The Joint Commission (NPSG 15.01.01) requires a validated suicide screen for patients 12 and older seen primarily for a behavioral condition. The four ASQ questions take about 20 seconds and identified 97% of at-risk youth aged 10–21 (Horowitz 2012); a yes to current thoughts of killing oneself is an acute positive needing an immediate safety evaluation. Universal screening nearly doubled detection (2.9% to 5.7%; Boudreaux 2016), and adding brief intervention cut later suicide attempts by 30% (ED-SAFE, Miller 2017).

Violence: watch for STAMP cues (staring, tone and volume, anxiety, mumbling, pacing; Luck 2007) or score the Brøset checklist (confused, irritable, boisterous, verbal threats, physical threats, attacking objects; >2 is very high risk), built for inpatient psychiatry. De-escalate first (Project BETA 2012: personal space, one speaker, short sentences, choices, clear limits). Restraint for violent or self-destructive behavior needs an order limited to 4 hours for adults, 2 for ages 9–17 and 1 under 9, and a face-to-face evaluation within 1 hour (CMS, 42 CFR 482.13(e)).

Behavior change is medical until shown otherwise: check glucose, SpO₂ and temperature and look for head injury, intoxication, withdrawal and delirium; v5 warns that a psychiatric or substance use history invites biased, lower levels.

Mistriage, reassessment and the evidence

Nurses matched the reference level on 59.2% of standardized scenarios in Brazil, the UAE and the US, 44.1% for high-acuity cases, with no gain from experience (Mistry 2018). Among 5.3 million adult visits at 21 Kaiser EDs, 32.2% were mistriaged, 3.3% under and 28.9% over; sensitivity for critical illness was 65.9%, 61% of visits were ESI 3, and Black patients had higher risk of both errors (Sax 2023).

Under-triage is the safety failure: it delays time-critical treatment. Over-triage is the capacity failure: true ESI 2 patients wait behind inflated ones, and in mass casualty incidents over-triage raised critical mortality by flooding resuscitation areas (Frykberg 2002). Experienced nurses tend to under-triage and newer nurses to over-triage (Levis-Elmelech 2022, cited in v5). Across triage scales, 3–45% of patients later admitted had been triaged level 4 or 5 (Hinson 2019).

Decision support targets the crowded middle: an e-triage model moved more than 10% of ESI 3 patients up, and they needed critical care or an emergency procedure in 6.2% versus 1.7% (Levin 2018); a commercial model matched the reference level 75.7% of the time versus 59.8% for nurses (Ivanov 2021). Both are retrospective comparisons, not outcome trials.

Reassessment: v5 sets no interval, so follow policy (CTAS uses 15, 30, 60 and 120 minutes for levels 2–5). Recheck abnormal vital signs, pain after analgesia and anyone who reports a change. Change the level only upward and only before the patient is placed, and document the change, the reason and your action; do not change it after a physician or APP has seen the patient, and never re-level to meet a door-to-ECG or door-to-CT metric (v5 Ch. 2, Appendix A).

CEN exam emphasis and pearls

The CEN outline effective July 2026 has 150 scored items (175 including 25 unscored pretest items, 3 hours; BCEN). Triage sits under Professional Issues, Prioritization, with mass casualty and patient throughput, in a 12-item domain; Mental Health Emergencies (13 items) covers aggressive and violent behavior and homicidal and suicidal ideation. Work triage items through A, B, C and D in order and ignore bed availability.

• ESI 1 needs an immediate lifesaving intervention; a stroke CT or cath lab in a stable patient is diagnostic
• Unresponsive: acutely nonverbal and not following commands, or P or U on AVPU
• ESI 2: high risk, new confusion (assume new if baseline unknown), or severe pain or distress; tell the charge nurse now
• Pain ≥7/10 means consider ESI 2: renal colic and sickle cell crisis yes, an isolated sprain no
• Count types: all labs 1, plain films 1, film plus CT 2, procedural sedation 2; splints, oral meds, tetanus, point-of-care tests 0
• High-risk adult vitals: HR >100, RR >20, SpO₂ <92%; recheck and up-triage if they persist
• T >38 °C at 28 days or younger: at least ESI 2
• Suicidal, homicidal, psychotic or violent: ESI 2; pregnant or postpartum SBP <90 or >150: ESI 2
• Re-level only upward, before placement, with documentation
• Under-triage risk: older adults, women with chest pain, patients of color, psychiatric or substance use history