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[L. delirium, madness, insanity]
An acute, reversible state of disorientation, inattention, and confusion.

Delirium is exceptionally common among older and hospitalized patients. It is found (in different surveys) in as few as 10% and as many as 90% of these populations.

Common causes include withdrawal from drugs and/or alcohol; side effects of medication; infections (esp. sepsis); pain; surgery or trauma; hypoxia; electrolyte and acid-base imbalances; sensory deprivation or sensory overload; dementia; hospitalization (esp. admission to an intensive care unit for longer than two days); depression (esp. but not exclusively in people 65 years or older).

Delirium is marked by disorientation without drowsiness; hallucinations or delusions; difficulty in focusing attention; inability to rest or sleep; and emotional, physical, and autonomic overactivity.

The health care professional should consider delirium whenever an acute change in mental status occurs and esp. when the mental status of patients is sometimes clear but at other times is profoundly confused and disoriented. There is no diagnostic clinical laboratory, physiological, or imaging test for delirium.

Preventive measures may sometimes reduce the risk of delirium in hospitalized patients. Such measures include providing glasses and hearing aids to patients with known sensory defects; mobilizing patients or providing range-of-motion activities several times each day and as early as possible during hospitalization; avoiding multiple new medications; maintaining hydration by encouraging oral fluid intake; using holistic measures to promote relaxation; introducing structured sleep protocols; reducing anxiety; and engaging family members or people with the care of delirious patients.

Treatment involves determining the cause of the delirium and removing or resolving it if possible.

Patients who experience an episode of delirium have reduced longevity compared to hospitalized patients with similar illnesses who do not; they also have an increased risk of prolonged cognitive impairment after the delirium resolves.

Supportive care consists of minimizing unanticipated, frightening, or invasive procedures; integrating orienting statements into normal conversation; and providing confused patients with a calm, supportive presence. When patients express deluded thoughts, it is important not to try to convince them that their perceptions are distorted. Speaking in a calm, clear voice, talking directly to the patient, using only simple statements and questions, and maintaining eye contact may be helpful. Maintaining caregiver consistency and encouraging family visiting are esp. beneficial. Delirious patients should be placed close to nursing stations so that they can be frequently observed. Physical protection from self-injury should be provided by bed alarms, wander guards, or mattresses placed on the floor to decrease the likelihood of patients' falling. Delirious patients should be permitted to sleep without interruption. Pain that they experience should be treated with analgesic drugs that do not affect mental status. Large calendars and clocks should be provided to aid orientation. Natural light should be used to distinguish day and night. Other useful preventive interventions include limiting interfacility transfers and room changes as much as possible and providing complementary therapies to decrease agitation and aggression, e.g., music therapy, massage, and shared activities. Antipsychotic drugs and benzodiazepines may be used cautiously when other nonpharmacological interventions have failed.

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