Delirium

ESSENTIAL DIAGNOSIS

Rapid onset and fluctuating course.
Primary deficit in attention rather than memory.
May be hypoactive or hyperactive.
Dementia frequently coexists.

General Considerations

Delirium is an acute, fluctuating disturbance of consciousness, associated with a change in cognition or the development of perceptual disturbances (see also Chapter 25). It is the pathophysiologic consequence of an underlying general medical condition such as infection, coronary ischemia, hypoxemia, or metabolic derangement. Delirium persists in up to 25% of patients and is associated with worse clinical outcomes (higher in-hospital and postdischarge mortality, longer lengths of stay, greater probability of placement in a nursing facility).

Although the acutely agitated elderly patient often comes to mind when considering delirium, many episodes are more subtle. Such quiet, or hypoactive, delirium may only be suspected if one notices new cognitive slowing or inattention.

Cognitive impairment is an important risk factor for delirium. Approximately 25% of delirious patients are demented, and 40% of demented hospitalized patients are delirious. Other risk factors are male sex, severe illness, hip fracture, fever or hypothermia, hypotension,malnutrition, polypharmacy and use of psychoactive medications, sensory impairment, use of restraints, use of intravenous lines or urinary catheters, metabolic disorders, depression, and alcoholism.

Clinical Findings

A number of bedside instruments for the assessment of delirium are available. The confusion assessment method (CAM), which requires (1) acute onset and fluctuating course and (2) inattention and either (3) disorganized thinking or (4) altered level of consciousness, is easy toadminister and performs well.

A key component of a delirium work-up is review of medications because a large number of drugs, the addition of a new drug, or the discontinuation of a medicationknown to cause withdrawal symptoms are all associated with the development of delirium. Medications that are particularly likely to increase the risk of delirium include opioids, benzodiazepines, dihydropyridines, and antihistamines.

Laboratory evaluation of most patients should include a complete blood count, electrolytes, blood urea nitrogen (BUN) and serum creatinine, glucose, calcium, albumin, liver function studies, urinalysis, and electrocardiography. In selected cases, serum magnesium, serum drug levels, arterial blood gas measurements, blood cultures, chest radiography, urinary toxin screen, head CT scan, and lumbar puncture may be helpful.

Prevention

Prevention is the best approach in the management of delirium. Measures include improving cognition (frequent reorientation, activities, socialization with family and friends, when possible), sleep (massage, noise reduction, minimizing interruptions at night), mobility, vision (visual aids and
adaptive equipment), hearing (portable amplifiers, cerumen disimpaction), and hydration status (volume repletion). No medications have been consistently shown to prevent delirium or reduce its duration or severity.

Treatment

Management of established episodes of delirium is largely supportive and includes reassurance and  reorientation, treatment of underlying causes, eliminating unnecessary medications, and avoidance of indwelling catheters and restraints. Antipsychotic agents (such as haloperidol, 0.5–1 mg, or quetiapine, 25 mg, at bedtime or twice daily) are considered the medication of choice when drug treatment of delirium is necessary. Other medications (eg, trazodone, acetylcholinesterase inhibitors, and mood stabilizers) have also been used, but evidence in support of these approaches is weak. In ventilated patients in the intensive care unit setting, dexmedetomidine or propofol (or both) may also be useful alternatives or adjuncts to antipsychotic therapy in patients with delirium.

Most episodes of delirium clear in a matter of days after correction of the precipitant, but some patients suffer episodes of longer duration, and a few never return to their former baseline level of functioning. These individuals merit closer follow-up for the development of dementia if not already diagnosed. 

When to Refer

If an initial evaluation does not reveal the cause of deliriumr if entities other than delirium are in the differential diagnosis, referral to a neuropsychologist, neurologist, or geropsychiatrist should be considered.

When to Admit

Patients with delirium of unknown cause should be admitted for an expedited work-up if consistent with the patient’s goals of care.