All About Delirium .info: Delirium

Delirium, acute confusional state, acute brain syndrome, acute cerebral insufficiency, or toxic-metabolic encephalopathy, is a disturbance of consciousness and cognition that develops over a short period of time, usually hours to days, fluctuates throughout the course of a day, and can be caused by a host of medical conditions, medications, or substances of abuse.

Delirium itself is NOT a disease, but rather a clinical syndrome (a set of symptoms), which result from an underlying disease or intoxication or withdrawal from an ingested substance.

Prevalence of Delirium

The overall prevalence of delirium in the community is just 1-2%, but approximately 15 – 75% of elderly people experience a delirium prior to or during a hospitalization (higher when more specialized populations are considered and in postoperative, intensive-care, subacute and palliative care settings). For example, in the general population the highest prevalence of delirium (often 50% to 75% of people) is generally seen in critically ill patients in the intensive care unit or ICU.

Age Is a Very Strong Predictor of Risk for Delirium

Age is also a very strong predictor of risk for delirium, and at least 20% of hospitalized patients over 65 years of age experience complications during hospitalization because of delirium each year. Also postoperative delirium occurs in 15-53% of surgical patients over the age of 65 years, and elderly patients admitted to an intensive care unit (ICU) experience delirium at a rate of 70-87%.

Dementia Is One of the Most Prominent Risk Factors for Delirium

Having dementia is one of the most prominent risk factors for delirium, with two-thirds of all cases of delirium occurring in patients with dementia. It appears that delirium and dementia are both associated with decreased cerebral blood flow or metabolism, inflammation, and cholinergic neurotransmitter deficiency.

The Major Causes of Delirium

The major causes are diseases of the central nervous system, major internal organs, fluid and electrolyte imbalances, and either intoxication or withdrawal from medications or substances of abuse.

Mechanisms of Delirium

Evidence suggests that hypoxemia, metabolic derangements, drug toxicity, inflammation and acute stress responses can all contribute markedly to disruption of neurotransmission leading to delirium. Neurotransmitters with possible roles in delirium include acetylcholine, dopamine, serotonin, norepinephrine, glutamate and alpha-aminobutyric acid; so the contributing mechanisms disrupt the normal amounts and availability of one or more of these neurotransmitters thereby leading to delirium.

Hypoxia or Metabolic Derangement Can Cause Delirium

Hypoxia or metabolic derangements lead to impairment of brain metabolism and in turn causes decreased synthesis and release of one or more neurotransmitters. This neurotransmitter imbalance in turn leads to disruption of normal nerve transmission resulting in delirium.

Substances and Medications Can Induce a Delirium

Substances and medications that can induce a delirium include; alcohol, amphetamines, cocaine, LSD, marijuana, peyote, psilocybin, phencyclidine, Ambien, Lunesta, barbiturates, benzodiazepines, meprobamate, Soma, opiate pain pills, heroin, and others. The common mechanism appears to be disruption of neurotransmitter balance leading to disruption of normal nerve transmission eventuating in delirium.

Systemic Inflammation Can Induce a Delirium

Inflammation releases cytokines, which are signaling molecules used extensively in intercellular communication, causing neurotransmitter imbalance and disruption of nerve transmission. Trauma, infection or surgery can lead to increased production of proinflammatory cytokines causing severe inflammation and impart a direct neurotoxic effect in the brain. Research has demonstrated that proinflammatory cytokine levels have been shown to be elevated in patients with delirium.

In addition, low-grade inflammation associated with chronic neurodegenerative changes in the brains of patients with dementia might explain why these individuals are at an increased risk for developing delirium.

The Acute Stress Response Can Induce a Delirium

High levels of cortisol associated with acute stress have been hypothesized to precipitate and/or sustain delirium. In elderly patients, feedback regulation of cortisol is often impaired, resulting in higher levels of baseline cortisol and thereby predisposing this population to delirium. Additionally, a number of studies have identified elevated levels of cortisol in people who developed postoperative delirium.

Duration of Delirium

The duration of delirium is typically affected by the underlying cause.

Treatment of Delirium

Treatment of delirium requires treatment of the underlying cause, and delirium can initiate a cascade of events that lead to a downward spiral of functional decline, loss of independence, institutionalization, and, ultimately, death.

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The Confusion Assessment Method (CAM) Diagnostic Algorithm for Detection of Delirium

The Confusion Assessment Method (CAM) to Detect Delirium

Delirium is an emergent condition, and prompt intervention is warranted to identify and treat the underlying cause and provide supportive care.

Risk factors for delirium include older age, prior cognitive impairment, presence of infection, severe illness or multiple co-morbidities, dehydration, psychotropic medication use, alcoholism, vision impairment and fractures.

Approximately 15 – 60 % of elderly people experience a delirium just prior to or during a hospitalization but the diagnosis is usually missed in up to 70% of cases.

Delirium is associated with poor outcomes in the hospital including prolonged hospital stays, functional decline, and increased use of chemical and physical restraints. After hospitalization, delirium increases the risk of subsequent nursing home admission.

Therefore,  people in the hospital at high risk for delirium should be assessed daily using a standardized tool to facilitate prompt identification and management.

The Confusion Assessment Method (CAM)

The Confusion Assessment Method (CAM) was originally developed in 1988-1990, to improve the identification and recognition of delirium.

The Confusion Assessment Method tool can be administered in less than 5 minutes, it identifies the presence or absence of delirium, but does NOT assess the severity of the delirium, making it less useful to detect clinical improvement or deterioration..

The Confusion Assessment Method (CAM) includes two parts. Part one is an assessment instrument that screens for overall cognitive impairment. Part two includes only those four features that were found to have the greatest ability to distinguish delirium or reversible confusion from other types of cognitive impairment.

Consider the diagnosis of delirium if 1 and 2, AND either 3a or 3b are positive:

1. Acute Onset and Fluctuating Course

Is there evidence of an acute change in mental status from the person’s normal baseline?

Did the (abnormal) behavior fluctuate during the day (tend to come and go, or increase and decrease in severity)?

2. Inattention

Did the person have difficulty focusing attention (e.g. being easily distractible) or have difficulty keeping track of what was being said?

3a. Disorganized Thinking

Was the person’s thinking disorganized or incoherent: such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject?

3b. Altered Level of Consciousness

Overall, how would you rate this person’s level of consciousness? (alert [normal], vigilant [hyper-alert], lethargic [drowsy, easily aroused], stupor [difficult to arouse], or coma [un-arousable]).

Positive for any answer other than “alert”.

Validation with psychiatric diagnosis revealed sensitivity of 94-100% and specificity of 90-95%.

Ref: Inouye, SK et al Annals Int Med 1990;113:941-48

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Delirium in Elderly Adults

Delirium in the Elderly

Delirium is a common and serious acute neuropsychiatric syndrome with core features of inattention and global cognitive dysfunction. Delirium is characterized by inattention and acute cognitive dysfunction, and it is a transient, reversible syndrome that is acute and fluctuating.

Etiologies of delirium are diverse, multifactorial and often reflect the pathophysiological consequences of an acute medical illness, medical complication or drug intoxication or withdrawal.

Delirium develops through a complex interaction between different risk factors, modifiable and non-modifiable alike. Delirium risk can result from a combination of predisposing, non modifiable factors, such as preexisting dementia or serious medical illness, or modifiable factors, such as ingestion of sedative medications, infections, abnormal electrolyte or metabolite levels, or surgery.

Overall prevalence of delirium in the community is just 1-2%, and delirium in general hospital admission is 14-24%. Delirium arising during a hospital stay ranges from 6% to as high as 56% (higher when more specialized populations are considered and in postoperative, intensive-care, subacute and palliative care settings).

However, in hospitalized patients over 65 years of age 20% experience complications during hospitalization,  15-53% develop postoperative delirium, and ICU psychosis (delirium) incidence can reach 70-87% in patients admitted to an intensive care unit (ICU).

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