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- A 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: Nervous
- Synonym(s): Acute confusional state; Altered mental status; Organic brain syndrome; Acute mental status change
- Predominant age: Older persons
- Predominant sex: Male = Female
>50% in high-risk older patients
- 10% in older emergency room patients
- 10–40% in hospitalized older patients
- 25% in older post–acute care patients
- Highest rates (>50%) in intensive care unit (ICU), post–hip fracture repair, post–cardiothoracic surgery
- Predisposing risk factors:
- Advanced age
- Prior cognitive impairment
- Functional impairment
- High BUN:Creatinine ratio
- Hearing or vision impairment
- Precipitating risk factors:
- Severe illness in any organ system(s)
- Need for a urinary catheter
- >3 medications
- Specific medications, especially long-acting sedative hypnotics (e.g., diazepam and flurazepam), narcotics (especially meperidine), and anticholinergics (especially diphenhydramine)
- Any adverse iatrogenic event
Follow treatment approach.
- 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 is a leading hypothesis.
- Multicomponent approach addressing contributing factors can reduce incidence and complications.
- Usually multifactorial
- Often interaction between predisposing and precipitating risk factors
- With more predisposing factors (i.e., frail patients), fewer precipitating factors are needed to produce delirium.
- If few predisposing factors (e.g., very robust patients), more precipitating factors are needed to manifest delirium.
Commonly Associated Conditions
Multiple, but most common are:
- New medicine or medicine changes
- Infections (especially lung and urine, but meningitis needs consideration as well)
- Toxic-metabolic (especially low sodium, elevated calcium, renal failure, and hepatic failure)
- Heart attack
- Alcohol or drug withdrawal
- Pre-existing cognitive impairment increases risk.