Skip to Main Content


Key Clinical Questions

  • image What is the prevalence of delirium in hospitalized patients?

  • image What are the most common causes of delirium?

  • image Why is it important to detect delirium?

  • image What are the symptoms of delirium?

  • image How is delirium diagnosed?

  • image How can delirium be prevented and treated?

Delirium is common in hospitalized patients. The prevalence of delirium may be as high as 80% in mechanically ventilated patients in the intensive care unit (ICU), 50% in geriatric postoperative patients, and 10% to 40% in general medical patients. Patients who develop delirium frequently have multiple risk factors. These include nonmodifiable factors, such as increased age, pre-existing cognitive impairment, and a history of prior stroke or brain injury. Important modifiable risk factors include (1) exposure to deliriogenic medications, (2) infection, (3) metabolic derangement, (4) organ failure, (5) dehydration, (6) malnutrition, (7) surgery, (8) immobility, (9) use of physical restraints, (10) sensory impairment, (11) sleep deprivation, (12) pain, and (13) drug withdrawal or intoxication.


Delirium as a red flag

  • Delirium is a nonspecific warning sign, like fever or hypotension, indicating that something serious may be wrong and requires further investigation. Thirty-nine percent of inpatients with delirium die within one year. Do not ignore this red flag.

Delirium is associated with increased mortality, morbidity, and length of stay. Estimates of annual US health care costs attributed to delirium range from $40 billion to $150 billion. Delirious patients require extra care following discharge from acute inpatient units and are at increased risk of being discharged to a skilled nursing facility rather than directly home. Patients often suffer from frightening memories of delirious episodes while hospitalized. Such experiences may result in appreciable anxiety and preoccupation long after delirium has cleared, impacting the patient’s quality of life for months to years. Family members are often distressed by the changed demeanor and behavior of their loved one, making care and support more challenging.


The central feature of delirium is an acute disturbance of consciousness accompanied by altered cognition or perception. Disruptions in brain function occur in the brainstem, thalamus, prefrontal cortex, fusiform cortex, and parietal lobes. This widespread cortical dysfunction is typically associated with diffuse and symmetric slowing of electrical activity on electroencephalography (EEG), although fast electrical activity occurs in some cases, especially in alcohol or sedative withdrawal.


  • The diagnosis of delirium requires diminished attention and awareness, evolving over a short period of time (hours to days), waxing and waning in severity, and associated with other disturbances in cognition, such as memory deficits and disorientation. Delirium cannot be wholly explained by a pre-existing neurologic disorder. History, physical examination, laboratory testing, and imaging should reveal one or more inciting factors, such as electrolyte disturbances, infections, adverse effects of medications, or drug and alcohol withdrawal syndromes.

Figure 81-1 depicts numerous potential pathways to delirium and underscores its ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.