Delirium
Formal Definition
An acute neuropsychiatric syndrome characterized by a disturbance in attention, awareness, and cognition that develops over hours to days, fluctuates over time, and is caused by a medical condition, substance, or medication; classified as hyperactive (agitation, combativeness), hypoactive (quiet, withdrawn — most common and most missed), or mixed; a medical emergency requiring urgent identification and treatment of the underlying cause.
How It's Used on the Ward
"Delirious" or "sundowning" (nighttime worsening) or "acute confusion" — altered mental status that is always secondary to something medically wrong.
Example
""76-year-old post-op day 2, was oriented yesterday, now fluctuating between agitation and somnolence, not recognizing family, worse at night: acute delirium. CAM assessment positive. Starting the delirium bundle: reorientation, sleep hygiene, glasses and hearing aids on, minimize sedating meds, early mobilization, pain control. Working up for precipitants: infection, metabolic, pain, urinary retention, constipation.""
Clinical Context
CAM (Confusion Assessment Method): acute onset + fluctuating course + inattention + either disorganized thinking OR altered level of consciousness = delirium (sensitivity 94–100%). Predisposing factors: age, dementia, sensory impairment, immobility. Precipitating factors (AEIOU TIPS mnemonic): Alcohol/drugs, Electrolytes, Infection, Oxygen deficit, Uremia, Trauma, Intracranial, Pain, Seizure, Sepsis. Hyperactive delirium is visible; hypoactive is missed (looks like depression or sedation). Avoid Haldol as first-line — reserve for safety risk only; it does not treat underlying cause. Non-pharmacological bundle (HELP protocol) is more effective than medications. ICU delirium independently associated with longer hospital stay, higher mortality, and long-term cognitive impairment.