By Jointra Editorial Team, Certified EMT
Altered mental status (AMS) is not a diagnosis — it's a symptom. It can result from dozens of different causes, many of which are life-threatening and time-sensitive. The EMS provider's job is not to diagnose the underlying cause (that happens in the hospital) but to identify reversible, immediately life-threatening causes and treat them while providing rapid transport.
A systematic framework for the AMS differential:
A — Alcohol (and other substances) Most common cause of AMS in many EMS systems. But never assume intoxication without ruling out other causes — a drunk patient can also be hypoglycemic or have a subdural hematoma.
E — Epilepsy (seizure and postictal state) Postictal confusion after a seizure can last minutes to hours. Look for tongue biting, incontinence, focal neurological deficits.
I — Insulin (hypoglycemia or hyperglycemia) Check glucose on every AMS patient. Non-negotiable. Hypoglycemia is rapidly reversible with treatment.
O — Overdose or poisoning Consider the toxidrome (see toxidrome article). Check for track marks, pill bottles, drug paraphernalia.
U — Uremia and metabolic causes Kidney failure, liver failure, electrolyte abnormalities (Na, Ca, glucose). Usually subacute onset.
T — Trauma Head injury — look for scalp lacerations, raccoon eyes, Battle's sign, blood in the ear canal, unequal pupils.
I — Infection Meningitis (fever + headache + stiff neck + photophobia), sepsis, encephalitis, UTI (especially in the elderly). Fever is not always present in the elderly.
P — Psychiatric Diagnosis of exclusion in the field. Never attribute AMS to psychiatric illness without ruling out medical causes.
S — Stroke and other structural causes FAST exam, focal neurological deficits, sudden onset. Also consider hypertensive emergency.
Pupils:
Blood glucose: Always. Every time.
Vital signs: Hyperthermia (infection, stimulants, serotonin syndrome), hypothermia, hypertension (hypertensive emergency, stimulants), hypotension (sepsis, overdose, hemorrhage).
Respiratory pattern: Cheyne-Stokes (herniation, CHF), Kussmaul (acidosis), slow and deep (opioids, herniation).
Skin: Diaphoresis (hypoglycemia, shock, MI), dry and flushed (anticholinergic, heat stroke), jaundice (liver failure), track marks (IV drug use).
Everything else waits for the hospital.