Delirium: Acute Confusion from Fever or Illness—Symptoms, Causes, and Urgency of Treatment

Definition

Delirium is an acute, fluctuating disturbance in attention, awareness, and cognition developing over hours-days, typically secondary to a medical condition. It is a medical emergency.

Core Features (DSM-5)

• Disturbance in attention (reduced ability to direct, focus, sustain, shift).
• Reduced awareness of environment.
• Cognitive change (memory deficit, disorientation, language disturbance, visuospatial impairment).
• Acute onset, fluctuating course.
• Not better explained by dementia (though can coexist).

Common Causes (PINCH ME Mnemonic)

• Pain, Poisoning (drugs, alcohol withdrawal)
• Infection (UTI, pneumonia, sepsis, COVID-19, meningitis)
• Nutrition (dehydration, electrolyte imbalance, thiamine deficiency)
• Cardiovascular (MI, HF, arrhythmia)
• Hypoxia, Hyper/hypoglycemia, Hyper/hypothyroidism
• Medications (anticholinergics, benzos, opioids, steroids, polypharmacy)
• Environment (ICU, sensory deprivation/overload, sleep deprivation)

Subtypes

• Hyperactive: Agitation, hallucinations, delusions, pulling lines.
• Hypoactive: Lethargy, somnolence, apathy — most common, most missed.
• Mixed: Alternating features.

Urgency of Treatment

• Identify and treat underlying cause(s).
• Non-pharmacologic: reorientation, glasses/hearing aids, sleep hygiene, mobilization, family presence.
• Pharmacologic (if safety risk): Low-dose haloperidol, risperidone, quetiapine; avoid benzodiazepines (except alcohol/benzo withdrawal).
• Delirium ↑ mortality, LOS, functional decline, dementia risk.