approach to altered mental status


Altered mental status carries a wide differential and requires a systematic approach. Traditionally we are taught some long mnemonic like AEIOUTIPS or IWATCHDEATH which are difficult to remember and represents a shotgun approach to assessment, investigations and treatment. It’s easier and more rational to use a systems-based approach, using the common ER mnemonics that reinforce pathophysiology and resuscitation.


B: CHEST: altered from hypoxia or hypercarbia

  • Hyperinflation: COPD causing CO2 narcosis
  • EST: effusion/sick pneumonia/tumour causing hypoxia

C: CARDIOVASCULAR: altered from hypertension or shock

  • RV strain (PE) and Dysfunction LV (MI can give altered mental status, especially in elderly
  • Outflow dissection: aortic dissection can cause stroke
  • Volume depletion Abdominal bleed Soft tissue bleed Child-breaing ectopic: altered from hypovolemic/hemorrhagic shock
  • Urticaria anaphylaxis Lactate sepsis Addisonian Rx: altered from distributive shock

D: NEURO: altered from intracranial process

  • Neuron seizure, including non-convulsive status
  • Encephalitis, meningitis, abscess
  • Unregulated pressure, e.g. VP shunt malfunction
  • RBC bleed, clot
  • Onco tumour

E: ENDO: altered from endocrine/metabolic

  • Electrolyte: hypoglycemia, hypercalcemia, hypo/hypernatremia
  • Normothermia: hypo/hyperthermia
  • D
  • Ormones: hyper/hypothyoid, pheo, hyper/hypoadrenal

F: CREATININE: altered from uremia

G: ABDOMINAL: altered from encephalopathy

  • Ammonia: liver failure


I: INTOX: altered from toxicity

  • Ingest: eg alcohol, marijuana, cocaine, heroin, ecstasy, GHB
  • Naturopathic
  • Treatment, e.g. benzo, opioid
  • OTC
  • X poison, eg carbon monoxide, heavy metals,



This approach emphasizes sequential analysis and resuscitation of body systems, and relevant investigations

  • A: assess airway –> intubate if can’t protect
  • B: assess breathing: resp rate, O2 sat, lung auscultation, lung EDE, consider CXR/ABG –> provide oxygenation/ventilation to correct oxygen/carbon dioxide, treat underlying
  • C: assess perfusion: rhythm, pump, volume, tone: HR, BP, ECG, consider Dimer, trop, Hgb, beta, WBC, lactate –> correct BP, treat underlying cause
  • D: assess neurologically, consider CT/LP –> treat underlying
  • E: check temp/glucose, measure electrolytes, TSH –> correct temperature, electrolytes, hormones
  • F: measure urea
  • G: measure ammonia if liver failure –> lactulose, treat cause
  • H
  • I: assess history of ingestions/withdrawal, prescription and non-prescription medications, and toxic exposures –> treat
  • J


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