Delirium is a topic covered in the 5-Minute Clinical Consult.

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  • A temporary neurologic complication of illness and/or medication(s), especially common in older patients, manifested by new confusion and impaired attention
  • A medical emergency requiring immediate evaluation to decrease morbidity and mortality
  • System(s) affected: neurologic
  • Synonym(s): acute confusional state, altered mental status, organic brain syndrome, acute mental status change, encephalopathy


  • Predominant age: older persons
  • Predominant sex: male = female

  • >50% in older ICU patients
  • 11–51% in postoperative patients
  • 10–40% in hospitalized older patients
  • 8–17% in older ED patients
  • 14% in older postacute care patients

Etiology and Pathophysiology

  • Multifactorial: believed to result from a decline in physiologic reserves with aging, resulting in a vulnerability to new stressors
  • Neuropathophysiology is not clearly defined; cholinergic deficiency, dopamine excess, and neuroinflammation are leading hypotheses.
  • Often interaction between predisposing and precipitating risk factors
  • With more predisposing factors (i.e., frail patients), fewer precipitating factors needed to cause delirium
  • If few predisposing factors (e.g., very robust patients), more precipitating factors needed to cause delirium
  • Multicomponent approach addressing contributing factors can reduce incidence and complications.

Risk Factors

  • Predisposing risk factors
    • Advanced age, >70 years
    • Preexisting cognitive impairment
    • Functional impairment
    • Dehydration; high BUN:creatinine ratio
    • History of alcohol abuse
    • Malnutrition
    • Hearing or vision impairment
    • Multiple comorbidities
  • Precipitating risk factors
    • Severe illness in any organ system(s)
    • Medical devices (urinary catheter, restraints)
    • Polypharmacy (≥5 medications)
    • Specific medications, especially benzodiazepines, opioids meperidine, and anticholinergics diphenhydramine, high-dose neuroleptics
    • Pain
    • Any iatrogenic event
    • Surgery
    • Sleep deprivation

General Prevention

Follow treatment approach.

Commonly Associated Conditions

Multiple but most common are the following:

  • New medicine or medicine changes
  • Infections (especially lung, urine, and blood stream, but consider meningitis as well)
  • Toxic metabolic (especially low sodium, elevated calcium, renal failure, and hepatic failure)
  • Heart attack or stroke
  • Alcohol or drug withdrawal
  • Preexisting cognitive impairment increases risk.

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