Altered mental status (ED workup — undifferentiated AMS)

Call 911 or go to the nearest emergency room right away if you have:

• Fingerstick glucose <70 mg/dL with AMS — D50W 50 mL IV stat; thiamine BEFORE glucose in alcoholics (PMID 32553711)(life-threatening)
• oxygen level (SpO₂) <90% (hypoxic encephalopathy) OR pCO2 >50 on ABG (CO2 narcosis from COPD/OSA) — O2 + BiPAP / intubation per phenotype
• Pinpoint pupils + bradypnea + AMS — naloxone 0.4-2 mg IV/IM/IN; titrate to RR; consider infusion for long-acting opioids (methadone, fentanyl analogs)(life-threatening)
• Infection source (pneumonia / UTI / skin / abdominal / meningitis) + qSOFA ≥2 OR lactate >2 OR SBP <100 + AMS → sepsis-encephalopathy (SSC 2026)
• Sudden focal deficit + AMS + LKW <24 h → STAT non-contrast head CT + CTA + tPA/thrombectomy pathway (Powers AHA 2019)(life-threatening)
• Sudden focal deficit + AMS + acute hypertension + anticoag → STAT non-contrast head CT shows ICH; BP control + reversal of anticoag + neurosurgery (AHA 2022)(life-threatening)
• Thunderclap headache + AMS ± focal deficit + meningismus → STAT non-contrast head CT (sensitivity >95% at 6 h); LP for xanthochromia if CT negative; CTA for aneurysm(life-threatening)
• Active convulsion >5 min OR ≥2 seizures without recovery between → status epilepticus; postictal AMS resolving within 30-60 min may need EEG for nonconvulsive status (Brophy NCS 2012)(life-threatening)
• Fever + AMS + meningismus / petechiae OR temporal-lobe MRI / CSF lymphocytic pleocytosis → empiric ceftriaxone + vancomycin + ampicillin + dexamethasone (bacterial) OR acyclovir (HSV) within 1 h (Tunkel IDSA PMID 22119250)(life-threatening)
• Na <120 mEq/L + AMS / seizure — 3% saline 100 mL bolus q10 min x 3 (max ΔNa 6-8 mEq/L per 24 h to avoid osmotic demyelination) (syndrome.hyponatremia.core.v1)(life-threatening)
• Na >160 mEq/L + AMS — controlled correction with hypotonic fluids; max ΔNa 10-12 mEq/L per 24 h (cerebral edema risk if too fast)
• K >6.5 mEq/L + ECG changes (peaked T, widened QRS, sine wave) + AMS — calcium gluconate + insulin/dextrose + albuterol + Kayexalate/patiromer + dialysis if refractory (syndrome.hyperkalemia.core.v1)(life-threatening)
• Known cirrhosis + AMS + asterixis + elevated ammonia → West Haven grade III/IV; lactulose + rifaximin + treat precipitant (GI bleed, SBP, dehydration, sedatives) (AASLD 2014)
• Hyperglycemia + AMS + (DKA: anion gap acidosis + ketones; HHS: osm >320, profound hyperglycemia >600, minimal ketones) → insulin infusion + IVF + K replacement (endo.dka.core.v1 / endo.hhs.core.v1)
• Thyroid storm (Burch-Wartofsky ≥45 — fever + tachy + AMS + GI + thyrotoxic) → PTU + propranolol + hydrocortisone + iodine; myxedema coma (hypothermia + bradycardia + hyponatremia + AMS + hypothyroid) → levothyroxine + hydrocortisone + passive rewarming (endo.thyroid-storm.core.v1 / endo.myxedema-coma.core.v1)(life-threatening)
• Acetaminophen / salicylate / toxic alcohols / CO / sympathomimetic / sedative-hypnotic / TCA / Na-channel blocker — universal acetaminophen + salicylate level + ethanol + UDS + osmolar gap + ABG with CO-Hb
• Alcohol use disorder or malnutrition + AMS / ataxia / ophthalmoplegia → Wernicke triad; thiamine 500 mg IV q8h x 2 days BEFORE glucose (PMID 32553711)