medicine 4.7 - confusion and delirium
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CALDERON, GARCIA, HARDIN, MANABAT, SOLIS 1 of 8
PLM CM
CONFUSION AND DELIRIUM 4
Hi guys! This trans is purely Harrisons-based (18th ed.)
OUTLINE INTRODUCTION CLINICAL FEATURES OF DELIRIUM RISK FACTORS EPIDEMIOLOGY PATHOGENESIS APPROACH TO THE PATIENT: DELIRIUM o HISTORY o PHYSICAL EXAMINATION o ETIOLOGY o LABORATORY AND DIAGNOSTIC EVALUATION
TREATMENT: DELIRIUM PREVENTION
INTRODUCTION Confusion a mental and behavioral state of reduced
comprehension, coherence, and capacity to reason
one of the most common problems encountered in medicine
accounting for a large number of emergency department visits, hospital admissions, and inpatient consultations
Delirium an acute confusional state remains a major cause of morbidity and mortality
rates costing billions of dollars yearly in health care
costs in the United States alone often goes unrecognized despite clear evidence
that it is usually the cognitive manifestation of serious underlying medical or neurologic illness.
CLINICAL FEATURES OF DELIRIUM Delirium is a clinical diagnosis that can be made only at the
bedside. Terms used to describe delirium
encephalopathy acute brain failure acute confusional state postoperative or intensive care unit (ICU)
psychosis Manifestation many clinical manifestations
defined as a relatively acute decline in cognition that fluctuates over hours or days.
Hallmark of Delirium
a deficit of attention, although all cognitive domainsincluding memory, executive function, visuospatial tasks, and languageare variably involved.
Associated symptoms
altered sleep-wake cycles perceptual disturbances such as
hallucinations or delusions affect changes autonomic findings that include heart rate and
blood pressure instability Clinical categories
Two broad clinical categories: o Hyperactive Subtype
-Classic example: cognitive syndrome associated with severe alcohol withdrawal -prominent hallucinations, agitation, and
hyperarousal, often accompanied by life-threatening autonomic instability -easily recognized
o Hypoactive Subtype -Exemplified by: opiate intoxication -withdrawn and quiet, with prominent apathy and psychomotor slowing -overlooked more often -associated with worse outcomes
Based on differential psychomotor features A useful construct, but patients often fall
somewhere along a spectrum between the hyperactive and hypoactive extremes, sometimes fluctuating from one to the other within minutes.
Therefore, clinicians must recognize the broad range of presentations of delirium to identify all patients with this potentially reversible cognitive disturbance.
Reversibilty of delirium
Emphasized because many etiologies, such as systemic infection and medication effects, can be treated easily.
long-term cognitive effects of delirium remain largely unknown and understudied
Some episodes of delirium continue for weeks, months, or even years
In some instances, delirium does not disappear because there is underlying permanent neuronal damage.
Even after an episode of delirium resolves, there may be lingering effects of the disorder.
A patients recall of events after delirium varies widely, ranging from complete amnesia to repeated reexperiencing of the frightening period of confusion in a disturbing manner, similar to what is seen in patients with posttraumatic stress disorder.
Persistence and High recurrence rates
may be due to inadequate treatment of the underlying etiology of the syndrome
RISK FACTORS
Effective primary prevention strategy for delirium
begins with identification of patients at highest risk, including those preparing for elective surgery or being admitted to the hospital
no single validated scoring system has been widely accepted as a screen for asymptomatic patients
multiple well-established risk factors for delirium
Two Most consistently identified risks
older age and baseline cognitive dysfunction
Individuals who are over age 65 or exhibit low scores on standardized tests of cognition develop delirium upon hospitalization at a rate approaching 50%.
Its uncertain if the two is truly independent risk factors.
Other predisposing factors:
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o sensory deprivation ( preexisting hearing and visual impairment)
o indices for poor overall health (baseline immobility, malnutrition, and underlying medical or neurologic illness)
In-hospital risks for delirium
use of bladder catheterization physical restraints sleep and sensory deprivation addition of three or more new medications Avoiding such risks remains a key
component of delirium prevention as well as treatment.
Development of postoperative delirium
Surgical and anesthetic risk factors: o specific procedures such as those
involving cardiopulmonary bypass o inadequate or excessive treatment of
pain in the immediate postoperative period
Relationship between delirium and dementia
complicated by significant overlap between the two conditions
not always simple to distinguish between them
serve as major risk factors for delirium: o Dementia o preexisting cognitive dysfunction
at least 2/3 of cases of delirium occur in patients with coexisting underlying dementia
Dementia with Lewy bodies
A form of dementia with parkinsonism characterized by:
o fluctuating course o prominent visual hallucinations o parkinsonism o attentional deficit that clinically
resembles hyperactive delirium.
Delirium in elderly
often reflects an insult to the brain that is vulnerable due to an underlying neurodegenerative condition
Development of delirium
sometimes heralds the onset of a previously unrecognized brain disorder.
EPIDEMIOLOGY
Delirium a common disease reported incidence has varied widely with the
criteria used to define the disorder Estimates of delirium in hospitalized patients
range from 14 to 56%, with higher rates reported for elderly patients and patients undergoing hip surgery.
Older patients in the ICU have especially high rates of delirium that range from 70 to 87%.
not recognized in up to 1/3 of delirious inpatients Delirium in the ICU:
o Diagnosis is problematic (cognitive dysfunction is often difficult to appreciate in the setting of serious systemic illness and sedation)
o should be viewed as an important manifestation of organ dysfunction not unlike liver, kidney, or heart failure.
Outside the acute hospital setting o delirium occurs in nearly 2/3 of patients in
nursing homes and in over 80% of those at
the end of life. These estimates emphasize the remarkably
high frequency of this cognitive syndrome in older patients, a population expected to grow in the upcoming decade with the aging of the baby boom generation.
In previous decades
an episode of delirium was viewed as a transient condition that carried a benign prognosis.
Now Delirium now has been clearly associated with
substantial morbidity rate and increased mortality rate and increasingly is recognized as a sign of serious underlying illness.
Recent estimates of in-hospital mortality rates among delirious patients have ranged from 25 to 33%, a rate similar to that of patients with sepsis.
Patients with an in-hospital episode of delirium have a higher mortality rate in the months and years after their illness compared with age-matched nondelirious hospitalized patients.
Delirious hospitalized patients have a longer length of stay, are more likely to be discharged to a nursing home, and are more likely to experience subsequent episodes of delirium; as a result, this condition has enormous economic implications.
PATHOGENESIS
Pathogenesis and anatomy of delirium
incompletely understood
Attentional deficit serves as the neuropsychological hallmark of delirium
appears to have a diffuse localization with the brainstem, thalamus, prefrontal cortex, and parietal lobes.
Focal lesions such as ischemic strokes rarely, have led to delirium in
otherwise healthy persons right parietal and medial dorsal
thalamic lesions have been reported most commonly, pointing to the relevance of these areas to delirium pathogenesis
Cortical and subcortical regions
Widespred disturbances in these regions cause delirium
Cause of delirium in most cases rather than a focal neuroanatomic cause
Electroencephalogram (EEG)
usually show symmetric slowing, a nonspecific finding that supports diffuse cerebral dysfunction, in persons with delirium
Acetylcholine deficiency
often plays a key role in delirium pathogenesis
Medications with anticholinergic
can precipitate delirium in susceptible individuals,
Therapies with cholinergic properties
designed to boost cholinergic tone e.x. cholinesterase inhibitors have, in small trials, been shown to
relieve symptoms of delirium Dementia patients susceptible to episodes of delirium
Those with Alzheimers pathology o known to have a chronic
cholinergic deficiency state due to degeneration of acetylcholine-producing
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neurons in the basal forebrain
Dementia with Lewy bodies o Another common dementia
associ- ated with decreased acetylcholine levels
o clinically mimics delirium in some patients
Other neurotransmitters
are also likely to be involved in this diffuse cerebral disorder
For example, increases in dopamine can also lead to delirium. o Patients with Parkinsons
disease treated with dopaminergic medications can develop a delirium-like state that features visual hallucinations, fluctuations, and confusion.
reducing dopaminergic tone with dopamine antagonists such as typical and atypical antipsychotic medications has long been recognized as effective symptomatic treatment in patients with delirium.
Not all individuals exposed to the same insult will develop signs of delirium
low dose of anticholinergic: o may have no cognitive
effects on a healthy young adult
o may produce a florid delirium in an elderly person with known underlying dementia.
extremely high dose of the same anticholinergic may lead to delirium even in healthy young persons.
This concept of delirium developing as the result of an insult in predisposed individuals is currently the most widely accepted pathogenic construct.
if a previously healthy individual with no known history of cognitive illness develops delirium in the setting of a relatively minor insult such as elective surgery or hospitalization, an unrecognized underlying neurologic illness such as a neurodegenerative disease, multiple previous strokes, or another diffuse cerebral cause should be considered.
delirium can be viewed as the symptom resulting from a stress test for the brain induced by the insult.
Exposure to known inciting factors
such as systemic infection and offending drugs
can unmask a decreased cerebral reserve
can herald a serious underlying and potentially treatable illness
APPROACH TO THE PATIENT: DELIRIUM Diagnosis clinical and is made at the bedside
careful history and physical examination is necessary in evaluating patients with possible confusional states
Screening tools
can aid physicians and nurses in identifying patients with delirium o Confusion Assessment Method (CAM) o Organic Brain Syndrome Scal o Delirium Rating Scale o Delirium Detection Score (in ICU) o ICU version of the CAM
These scales are based on criteria from the American Psychiatric Associations Diagnostic and Statistical Manual of Mental Disorders (DSM) or the World Health Organizations International Classification of Diseases (ICD)
These scales do not identify the full spectrum of patients with delirium.
Using CAM diagnosis of delirium is made if there is
acute onset and fluctuating course inattention accompanied by either disorganized thinking or altered level of consciousness.
Acutely confused patients
should be presumed delirious regardless of their presentation due to the wide variety of possible clinical features.
Not essential for diagnosis
A typical course that fluctuates over hours or days and may worsen at night (termed sundowning)
Observation Will reveal an altered level of consciousness or a deficit of attention.
Other hallmark features
alteration of sleep-wake cycles thought disturbances such as hallucinations or
delusions autonomic instability changes in affect.
HISTORY
Accurate history
difficult to elicit in delirious patients who have altered levels of consciousness or impaired attention
Information from collateral source
such as a spouse or another family member is invaluable.
3 Most important pieces of history
patients baseline cognitive function the time course of the present illness current medications
Premorbid cognitive function
can be assessed through the collateral source or, if needed, via a review of outpatient records
Delirium by definition
represents a change that is relatively acute, usually over hours to days, from a cognitive baseline.
As a result, an acute confusional state is nearly impossible to diagnose without some knowledge of baseline cognitive function.
Without this information, many patients with dementia or depression may be mistaken as delirious during a single initial evaluation.
Patients with a more hypoactive, apathetic presentation with psychomotor slowing may be identified as being different from baseline only through conversations with family members.
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A number of validated instruments have been shown to diagnose cognitive dysfunction accurately by using a collateral source: o modified Blessed Dementia Rating
Scale o Clinical Dementia Rating (CDR).
Baseline cognitive impairment is common in patients with delirium.
Even when no such history of cognitive impairment is elicited, there should still be a high suspicion for a previously unrecognized underlying neurologic disorder
Time course of cognitive change
Establishing this is important not only to make a diagnosis of delirium but also to correlate the onset of the illness with potentially treatable etiologies such as recent medication changes or symptoms of systemic infection.
Medications remain a common cause of delirium, especially compounds with anticholinergic or sedative properties
1/3 of all cases of delirium are secondary to medications, especially in the elderly.
Medication histories should include o all prescription as well as over-the-
counter o herbal substances taken by the patient o any recent changes in dosing or
formulation o substitution of generics for brand-name
medications. Other important elements of the history
screening for symptoms of organ failure or systemic infection, which often contributes to delirium in the elderly
common in younger delirious patients: o A history of illicit drug use o Alcoholism o toxin exposure
other symptoms that may accompany delirium, such as depression and hallucinations, may help identify potential therapeutic targets.
PHYSICAL EXAMINATION
General Careful screening for signs of infection o Fever o Tachypnea o pulmonary consolidation o heart murmur o stiff neck
fluid status should be assessed; both dehydration and fluid overload with resultant hypoxemia have been associated with delirium, and each is usually easily rectified
appearance of the skin can be helpful o jaundice in hepatic
encephalopathy o cyanosis in hypoxemia o needle tracks in patients using
intravenous drugs Neurologic requires a careful assessment of
mental status Patients with delirium often present
with a fluctuating course diagnosis can be missed when one
relies on a single time point of
evaluation Some but not all patients exhibit the
characteristic pattern of sundowning, a wors- ening of their condition in the evening.
In these cases, assessment only during morning rounds may be falsely reassuring.
Altered level of consciousness
ranging from hyperarousal to lethargy to coma is present in most patients with delirium
can be assessed easily at the bedside
Patients w/ normal level of consciousness
screen for an attentional deficit (classic neuropsychological hallmark of delirium)
Attention can be assessed while taking a history
from the patient Tangential speech
o fragmentary flow of ideas, or inability to follow complex commands often signifies an attentional problem
There are formal neuropsychological tests to assess attention, but a simple bedside test of digit span forward is quick and fairly sensitive.
In this task, patients are asked to repeat successively longer random strings of digits beginning with two digits in a row.
Average adults can repeat a string of five to seven digits before faltering; a digit span of four or less usually indicates an attentional deficit unless hearing or language barriers are present.
Forman neuropsychological testing
can be extraordinarily helpful in assessing a delirious patient
usually too cumbersome and time-consuming in the inpatient setting
Simple Mini Mental Status Examination (MMSE)
can provide some information regarding orientation, language, and visuospatial skills
performance of some tasks on the MMSE such as spelling world backward and serial subtraction of digits will be impaired by delirious patients attentional deficits alone and are therefore unreliable
New focal neurologic deficits
Focus of remainder of the screening neurologic examination
Focal strokes or mass lesions in isolation o rarely the cause of delirium, but
patients with underlying extensive cerebrovascular disease or neurodegenerative conditions may not be able to cognitively tolerate even relatively small new insults
Signs of neurodegenerative conditions
Screen for parkinsonism, which is seen not only in idiopathic Parkinsons disease but also in other dementing conditions such as Alzheimers
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disease, dementia with Lewy bodies, and progressive supranuclear palsy.
Motor examination presence of multifocal myoclonus or asterixis is nonspecific but usually indicates a metabolic or toxic etiology of the delirium.
ETIOLOGY Etiologies Some can be easily discerned through a
careful history and physical examination others require confirmation with laboratory
studies, imaging, or other ancillary tests A large, diverse group of insults can lead
to delirium, and the cause in many patients is often multifactorial.
Prescribed, pver-the-counter, and herbal medications
common precipitants of delirium Drugs with anticholinergic properties,
narcotics, and benzodiazepines are especially common offenders, but nearly any compound can lead to cognitive dysfunction in a predisposed patient.
elderly patient with baseline dementia may become delirious upon exposure to a relatively low dose of a medication
less susceptible individuals may become delirious only with very high doses of the same medication
importance of correlating the timing of recent medication changes, including dose and formulation, with the onset of cognitive dysfunction
Illicit drugs and toxins
common causes of delirium, especially in younger patients
increase in delirious young persons presenting to acute care settings due to recent rise in availability of so-called club drugs, o methylenedioxymethamphetamine
(MDMA, ecstasy), o -hydroxybutyrate (GHB) o phencyclidine (PCP)-like agent
ketamine Many common prescription drugs such as
oral narcotics and benzodiazepines are often abused and readily available on the street.
Alcohol intoxication with high serum levels can cause confusion
withdrawal from alcohol o more commonly leads to a classic
hyperactive delirium Alcohol and benzodiazepine withdrawal
o should be considered in all cases of delirium
o patients who drink only a few servings of alcohol every day can experience relatively severe withdrawal symptoms upon hospitalization
Metabolic abnormalities
electrolyte disturbances of sodium, calcium, magnesium, or glucose o can cause delirium
mild derangements o can lead to substantial cognitive
disturbances in susceptible individuals
Other common metabolic etiologies:
o liver and renal failure o hypercarbia and hypoxemia o vitamin deficiencies of thiamine
and B12 o autoimmune disorders including
central nervous system (CNS) vasculitis
o endocrinopathies such as thyroid and adrenal disorders.
Systemic infections
often cause delirium, especially in the elderly
common scenario o involves the development of an
acute cognitive decline in the setting of a urinary tract infection in a patient with baseline dementia.
Pneumonia, skin infections such as cellulitis, and frank sepsis also can lead to delirium.
septic encephalopathy o often seen in the ICU o probably due to the release of
proinflammatory cytokines and their diffuse cerebral effects.
CNS infections o such as meningitis, encephalitis,
and abscess o less common etiologies of delirium o high mortality rates associated with
these conditions when they are not treated quickly,
o clinicians must always maintain a high index of suspicion.
Exposure to unfamiliar environment of a hospital
In some susceptible individuals, this can lead to delirium.
usually occurs as part of a multifactorial delirium
should be considered a diagnosis of exclusion after all other causes have been thoroughly investigated
Many primary prevention and treatment strategies for delirium involve relatively simple methods to address the aspects of the inpatient setting that are most confusing.
Cerebrovascular etiologies
usually due to global hypoperfusion in the setting of systemic hypotension from heart failure, septic shock, dehydration, or anemia.
Focal strokes in the right parietal lobe and medial dorsal thalamus o rarely can lead to a delirious state
new focal stroke or hemorrhage o more common scenario causring
confusion in a patient who has decreased cerebral reserve
o sometimes difficult to distinguish between cognitive dysfunction resulting from the new neurovascular insult itself and delirium due to the infectious, metabolic, and pharmacologic complications that can accompany hospitalization after stroke.
Seizures intermittent seizures o may be overlooked when one is
considering potential etiologies,
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because a fluctuating course often is seen in delirium
nonconvulsive status epilepticus and recurrent focal or generalized seizures followed by postictal confusion o can cause delirium o EEG remains essential for this
diagnosis. Seizure activity spreading from an
electrical focus in a mass or infarct can explain global cognitive dysfunction caused by relatively small lesions.
Terminal restlessness
patients experience delirium at the end of life in palliative care settings
must be identified and treated aggressively
an important cause of patient and family discomfort at the end of life
It should be remembered that these patients also may be suffering from more common etiologies of delirium such as systemic infection.
LABORATORY AND DIAGNOSTIC EVALUATION Cost-effective
approach to the diagnostic evaluation of delirium that allows the history and physical examination to guide tests
No established algorithm for workup will fit all delirious patients due to the staggering number of potential etiologies o one stepwise approach is detailed in
Table 25-2. If a clear precipitant is identiied early
o such as an offending medication o little further workup is required
If no likely etiology is uncovered with initial evaluation o an aggressive search for an underlying
cause should be initiated Basic screening labs
Should be obtained in all patients w/ delirium: o complete blood count o electrolyte panel o tests of liver and renal function
In elderly patients o screening for systemic infection is
important o chest radiography o urinalysis and culture o possibly blood cultures
In younger individuals o serum and urine drug and toxicology
screening may be appropriate early in the workup.
patients in whom the diagnosis remains unclear after initial testing
o Additional laboratory tests addressing other autoimmune, endocrinologic, metabolic, and infectious etiologies should be reserved.
Brain imaging
often unhelpful if the initial workup is unrevealing
o most clinicians quickly move toward imaging of the brain to exclude structural causes.
noncontrast CT scan o can identify large masses and
hemorrhages o relatively insensitive for discovering an
etiology of delirium MRI Able to identify most acute ischemic strokes provides neuroanatomic detail that gives clues to
possible infectious, inflammatory, neurodegenerative, and neoplastic conditions
test of choice MRI techniques are limited by:
o availability o speed of imaging o patient cooperation o contraindications to magnetic exposure
Many clinicians begin with CT scanning and proceed to MRI if the etiology of delirium remains elusive
Lumbar puncture (LP)
must be obtained immediately after appropriate neuroimaging in all patients in whom CNS infec- tion is suspected.
Spinal fluid examination o can also be useful in identifying
inflammatory and neoplastic conditions and
o diagnosis of hepatic encephalopathy
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through elevated cerebrospinal fluid (CSF) glutamine levels.
LP should be considered in any delirious patient with a negative workup.
EEG does not have a routine role in the workup of delirium
remains invaluable if seizure-related etiologies are considered
TREATMENT: DELIRIUM Management of delirium
begins with treatment of the underlying inciting factor o patients with systemic infections should
be given appropriate antibiotics o underlying electrolyte disturbances
judiciously corrected These treatments often lead to prompt
resolution of delirium. Blindly targeting the symptoms of delirium
pharmacologically o only serves to prolong the time patients
remain in the confused state o may mask important diagnostic
information medications used to boost cholinergic
tone in delirious patients o led to mixed results o not currently recommended
Simple methods of supportive care
can be highly effective in treating patients with delirium
Can reduce confusion: o Reorientation by the nursing staff and
family o visible clocks and calendars o outside-facing windows
Sensory isolation o should be prevented by providing
glasses and hearing aids to patients who need them
Sundowning o can be addressed to a large extent
through vigilance to appropriate sleep-wake cycles.
During the day o a well-lit room should be accompanied
by activities or exercises to prevent napping.
At night o a quiet, dark environment o limited interruptions by staff o assure proper rest
sleep-wake cycle interventions o important in the ICU setting as the
usual constant 24-h activity commonly provokes delirium
Attempting to mimic the home environment as much as possible o has been shown to help treat and even
prevent delirium. Visits from friends and family throughout
the day o minimize the anxiety associated with
the constant flow of new faces of staff and physicians.
Allowing hospitalized patients to have access to home bedding, clothing, and nightstand objects o makes the hospital environment less
foreign and therefore less confusing. Simple standard nursing practices:
o Ex. maintaining proper nutrition and volume status
o Ex. managing incontinence and skin breakdown
o help alleviate discomfort and resulting confusion
Acute management
required in some instances where patients pose a threat to their own safety or to the safety of staff members
Bed alarms and personal sitters vs physical restraints o more effective o much less disorienting
Chemical restraints o should be avoided o when necessary, very low dose typical
or atypical antipsychotic medications administered on an as-needed basis are effective.
association of antipsychotic use in the elderly with increased mortality rates o underscores the importance of using
these medications judiciously and only as a last resort
Benzodiazepines
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o not as effective as antipsychotics o often worsen confusion through their
sedative properties. o Still used by many clinicians to treat
acute confusion o use should be limited to cases in which
delirium is caused by alcohol or benzodiazepine withdrawal
PREVENTION
It is extremely important to develop effective strategy to prevent delirium in hospitalizations, because of: o high morbidity associated with delirium o tremendously increased health care costs that
accompany it First step:
o Successful identification of high-risk patients followed by:
o initiation of appropriate interventions One trial randomized more than 850 elderly inpatients to
simple standardized protocols used to manage risk factors for delirium, including cognitive impairment, immobility, visual impairment, hearing impairment, sleep deprivation, and dehydration.
Significant reductions in the number and duration of episodes of delirium were observed in the treatment group, but unfortunately, delirium recurrence rates were unchanged.
Recent trials in the ICU have focused on identifying sedatives, such as dexmedetomidine, that are less likely to lead to delirium in critically ill patients.
All hospitals and health care systems should work toward developing standardized protocols to address common risk factors with the goal of decreasing the incidence of delirium.