Delirium

last authored: Feb 2012, David LaPierre
last reviewed:

 

 

Introduction

Delirium is a disturbance in consciousness, along with a change in cognition (memory, disorientation, language disturbance), due to a general medical condition. It is very common, underdiagnosed, and can have a significant impact of health of the patient and the comfort of everyone involved, especially family and caregivers.

Delirium is distinguished from other changes in mental status such as dementia by it's occurrence over a short period of time (hours to days), and its tendency to fluctuate.

 

Delirium can be the only sign of illness, and should prompt a thorough investigation into potential causes. Unfortunately, it is often unrecognized by health care providers.

 

It can have signficant impact the patient's management and outcomes. There is a loss of independence, increased risk of morbidity and mortality, with rates as high as 22-76% (ref).

 

 

 

Symptoms tend to be present from each of the following categories:

• consciousness and attention
• cognition (illusions and hallucinations, impaired thinking and comprehension, inhcoherence)
• psychomotor (hypo- or hyperreactivity, increased reaction time, increased or decreased speech)
• sleep disturbance (wake cycle disruption, daytime drowsiness, nocturnal worsening of symptoms, disturbing dreams or nightmares)
• emotional (depression, anxiety, irritability, euphoria, apathy, perplexity)

 

 

 

 

 

The Case of Ms. Dewar

Ms. Dewar is an 86 year-old woman admitted to the hospital with a hip fracture. Post-operative day two, her nurse nitces she is agitated, yelling at her roommates and attempting to climb out of her bed.

• how would you diagnose delirium?
• what investigations would you order?
• how would you treat her symptoms?

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Causes and Risk Factors

Infection and medications are most common causes of delirium.

Medications:  alcohol: intoxication, withdrawal, Wernicke-Korsakoff antidepressants: SSRIs, TCA anticholinergics: tri-cyclic antidepressants, muscle relaxants atropine, benztropine, scopolamine, warfarin sedatives, narcotics, anesthetics, anticonvulsants, dopinergic agents, steroids, insulin, glyburide, NSAIDs lithium digoxin	Organ failure shock congestive heart failure hepatic failure azotemia hypothyroidism hypoxia, hypercapnia hypertensive encephalopathy hypothermia
Infection:  urinalysis pneumonia encephalitis, meningitis abscess, sepsis	Acute metabolic disorder:  ketoacidosis hypo, hyperglycemia hypomagnesemia hypercalcemia parathyroid adrenal
Other constipation pain trauma: head injury, postoperative CNS pathology: stroke, hemorrhage, tumour, seizures, Parkinson's, vasculitis hypoxia: anemia, cardiac failure, pulmonary embolus deficiencies: vitamin B12, folic acid, thiamine  Heavy metals: arsenic, lead, mercury

 

Risk factors for developng delirium include:

• hospitalization (incidence 10-40%), major surgery, ICU stay
• nursing home residents (incidence 60%)
• childhood (febrile illness)
• old age (65+)
• male
• previous delirium
• unfamiliar settings
• multiple medications
• poor social contacts
• poor baseline vision or hearing
• poor nutrition or dehydration
• catheterization
• severe illness: cancer, AIDS
• pre-existing cognitive impairment
• recent anesthesia
• substance abuse

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Pathophysiology

There is no pathophysiologic explanation for delirium, though it likely results from interplay between acute illness and cognitive frailty. There is usually some global cortical dysfunction underlying the condition.

 

Theories for the precipitation of delirium include:

• alterations in neurotransmitters: decreased GABA, increased dopamine, increased acetylcholine
• decreased cerebral blood flow
• altered blood brain barrier function

Nocturnal diurnal variation is common in dementia.

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Signs and Symptoms

Disturbance in consciousness can include reduced clarity of awareness of the environment, with reduced ability to focus, sustain, or shift attention. These disturbances develop over a short time (usually hours to days) and tend to fluctuate over the course of a day. This is in contrast to dementia, which shows an irreversible decline over time. 

 

Upon history, physical exam, or lab findings, direct physiological causes can be found.

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Investigations

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Differential Diagnosis

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Prevention

The NICE has produced a set of evidence-based recommendations for the prevention and management of delirium (O'Mahony et al, 2011).

Pain management is important

Provide activities for patients to perform at the time.

Melatonin and tryptophan can be used to regulate sleep.

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Treatments

The NICE has produced a set of evidence-based recommendations for the prevention and management of delirium (O'Mahony et al, 2011).

Stop unnecessary medications.

Start low, go slow, and go all the way.

Benzodiazepine withdrawal can lead to rebound effect.

Removing unnecessary medications allow the most desired medications to bind.

Behavioural management options are best.

 

Antipsychotics have increased risk of mortality. The risk appears greatest with haldoperidol >olanzapine >risperidone >valproic acid > quetiapine.

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Consequences and Course

2x mortality, 7x if not detected (Siddiqi, 2006)

Up to 50% mortality rate one year after an episode of delirium.

Up to 76% mortality rates in hospitalized pts

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Additional Resources

O'Mahoney R. 2011. Synopsis of the National Institute for Health and Clinical Excellence guideline for prevention of delirium. Ann Intern Med. 154(11):746-51.

Wong CL et al. 2010. Does this patient have delirium? value of bedside instruments. JAMA. 304(7):779-86.

Siddiqui. 2006 Age Aging

Inouye  2006. NEJM. 354:1157-65.

Preventing Delerium (NEJM, 1999)

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Topic Development

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