Acute cognitive changes and disturbances of consciousness usually as a result of an underlying medical illness or due to a medication.

Delirium manifests as acute, fluctuating failure of the brain to support normal arousal, attention, and organized thinking.

A reversible state of impaired cognition, inattention, and altered level of consciousness

Incidence is high in critically ill patients.

It is the most common manifestation of acute brain dysfunction during critical illness, affecting 50-75% of patients who receive mechanical ventilation in an ICU.

Delirium is associated with increased mortality and decreased long-term cognitive function.

According to the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), the criteria for delirium are:

A. A disturbance in attention (ie, reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment).

B. The disturbance develops over a short time (usually hours to a few days), represents a change from baseline attention and awareness, and tends to fluctuate in severity during the course of a day.

C. An additional disturbance in cognition (eg, memory deficits, disorientation, language, visuospatial ability, perception).

D. The disturbances in attention, awareness, and cognition aren’t better explained by another preexisting or evolving neurocognitive disorder and don’t occur in the context of a severely reduced level of arousal.

E. History, physical, or laboratory findings show that the disturbance is caused by the direct physiologic consequences of a general medical condition, substance intoxication/withdrawal, exposure to a toxin, or multiple etiologies.

Individual 65 years or older especially those with dementia, evidence of prior cognitive decline, or prior neurological insult are at increased risk of delirium.

Delirious patients stay hospitalized longer and are more likely to be discharged to a facility instead of home.

Consequences of delirium include increased in-hospital and one year mortality rates, as well as worsened neurocognitive outcomes.

Patients with delirium have a higher mortality, longer periods of mechanical ventilation and hospital stays, higher costs, higher risk of long-term cognitive impairment in patients who do not have delirium.

An estimated 20-30% of elderly patients admitted to hospital wards experience delirium.

Agitated delirium is problematic in patients receiving mechanical ventilation because it increases the risk of self-extubation and removal of other essential medical devices.

Interferes with medical care with hyperactive delirium leading to unplanned removal of devices, and hypoactive delirium preventing participation in nursing interventions, physical therapy, and occupational therapy.

Associated with altered and shifting mental status and inability to focus, sustain or shift attention.

Associated with memory impairment, disorientation as to time or place, and language disturbance.

Clinical diagnosis based on the presence of 2 major features: disruption of attention and disruption of the sleep-wake cycle, leading to fluctuations in symptoms over the course of a day.

May be associated with impaired perception seeing or hearing things that are not present, abnormal speech, abnormal movements such as tremors or picking at clothing, disruptive behavior and sudden changes in emotional status.

Associated with a decreased ability to focus, to sustain or shift attention, and impaired cognition, possible perceptual disturbance that tends to fluctuate over the course of a day.

Clinical features include: acute onset, fluctuating course, disorganization, inability to maintain attention, altered level of consciousness, disorientation, impaired memory, perceptual abnormalities, altered psychomotor activity, and disturbance in the sleep-wake cycle (Inouye SK).

it is distinguishable from dementia and at its onset is extremely acute and rapid, whereas dementia is a more gradual process in its progression.

It is distinguishable from dementia, as well, by the presence of alteration in level of consciousness.

Presents in one of two major forms-hypoactive or hyperactive.

Hypoactive delirium is characterized by lethargy and slowed psychomotor functioning.

Hyperactive delirium characterized by agitation, hallucinations, and increased vigilance,

Hypoactive delirium is often not recognized by caregivers, while the hyperactive form is much more easily noted.

Patients may fluctuate between hypo active and hyperactive behavior (Liptzin B).

A transient global disorder of condition that is commonly hospitalized patients.

Almost 30% of older patients age 65 or older experience delirium at some time during hospitalization, and 40% of older patients in ICUs have delirium.

ICU delirium associated with an increased mortality, prolonged mechanical ventilation, prolonged hospitalization stay, and cognitive impairment in patients discharged.

When associated with hospitalization and older patients is an independent marker for increased mortality during the first 12 months after hospitalization (McCusker J).

Associated with a longer hospital stay, increased risk of hospital acquired complications, persistence of impaired cognition, and increased rates of discharge to long-term care facilities.

The process is frequently undiagnosed and when diagnostic criteria defined in The Diagnostic and Statistical Manual of Mental Disorders (DSM- III) applied to 133 consecutively admitted patients to an acute medical facility, led to the diagnosis in 20 patients, only one of which was recognized by the primary physician (Cameron DJ).

Frequently associated with iatrogenic processes including drug reactions, complications of procedures, stress, and forced immobilization ( Inouye SK).

Refers to an onset of short duration from hours to days and change over the course of a day.

May be the most common acute cognitive dysfunction in hospitalized patients occurring in 11%-26% of elderly medical or geriatric patients.

Cost of care $100 billion annually.

Elderly at high risk.

Risk factors include dementia, stroke, Parkinson’s disease, sensory impairment, polypharmacy, infection, dehydration, the use of restraints, and catheters.

Predisposing factors include preexisting dementia, severe illness, comorbidity, advanced age, chronic renal insufficiency, dehydration, malnutrition, depression, surgery, visual or hearing impairment, polypharmacy and myocardial infarction.

Common causes include: Metabolic derangements such as hypoglycemia or liver failure, infections such as sepsis or pneumonia, toxic effects of drugs or alcohol use, withdrawal states from alcohol or benzodiazepines, fluid and electrolyte disturbances such as hyponatremia, primary brain disorders such as meningitis, seizures, strokes, or Wernecke’s encephalopathy, low perfusion states such as heart failure or hypoxemia, phyysical disorders such as fractures, postoperative states, and reactions to medications.

Associated with prolonged hospital stay, functional decline, morbidity, mortality and nursing home placement.

Prevalence about 20% in elderly hospitalized medical patients, and can be as high as 60% after some types of surgery, and approaches 80% for elderly individuals admitted to a critical care unit.

Risk of delirium after hip repair in the elderly among the highest of surgical procedures.

Associated costs of more than $100 billion annually.

Associated with a threefold greater likelihood of placement in the long-term healthcare facility and a twofold higher one-year mortality.

Cause suggested to be a reversible impairment of cerebral oxidative metabolism along with neurotransmitter abnormalities.

Relationship exists between cholinergic and dopaminergic pathways in the brain.

Impaired cholinergic transmission occurs when anticholinergic drugs are used or with Alzheimer’s disease resulting in heightens risk for delirium.

Delirium is also seen with increased dopaminergic transmission.

Primary treatment for delirium is control of symptoms with antipsychotic or sedative medications which may provide short-term symptom relief.

Antipsychotic and sedative medications may prolong the duration of delirium and worsen clinical outcomes and overall do not improve the patient’s prognosis.

Anti-dopaminergic medications commonly used for treatment included haloperidol, risperidone, olanzapine, and quetiapine are not recommended for older patients.

Haloperidol, a typical antipsychotic medication often used to treat delirium, despite randomized trials that show no shorter duration of delirium in the ICU than placebo.

In ICU delirium treated with haloperidol did not lead to a significantly greater number of days alive and out of the hospital at 90 days than placebo.

In a large double-blind randomized placebo controlled trial there was no evidence that the use of haloperidol or ziprazadone had an effect on the duration of delirium among patients with respiratory failure or shock in the ICU (MIND-USA Investigators).

Prevention is the primary therapeutic goal.

Postoperative delirium is a common important complication for elderly patients and may relate to the dose of anesthetic drugs used.

Bispectral index utilizes an EEG from three frontotemporal electrodes using algorithms to generate a single number from 0 to 100 that represents the level of consciousness.

Meta analyses of trials report that EEG guided anesthetic administration reduces postoperative delirium by 1/3 to 1/2.

It is suggested postoperative delirium reduction may be due to the avoidance of burst suppression, an electroencephalographic pattern suggesting excessively deep anesthesia.

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