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Lecture

DeliriumNotes.docx

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Department
Nursing
Course Code
NURSING 2LA2
Professor
Kirsten Culver

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Pathophysiology: Delirium *Areas in italics are portions dictated throughout module. *Notes begin on slide #3. Slide: Delirium  Common, life threatening and potentially preventable clinical syndrome, induced by a variety of physical causes.  Often defined as an acute decline in the cognitive processes of the brain, namely attention and cognition.  Most strongly associated with hospitalized patients 65 years of age and older.  Patients with delirium may exhibit periods of inattention, disorganized thinking, changes in LOC, disorientation, delusions, perceptual disturbances, as well as impaired memory, speech, sleep, and psychomotor activity.  These changes in cognitive function can fluctuate in severity throughout the day and as such, delirium is often under-recognized and under-treated.  Estimated that 2/3 of patients go unreported.  This can be attributed to the syndromes fluctuating nature and the wide range of symptoms and patient characteristics associated with the syndrome.  Some clinicians continue to use the term confusional state or encephalopathy, when diagnosing delirium, further complicating the proper identification, management and treatment of this life- threatening syndrome. Slide: Delirium  As mentioned, delirium frequently accompanies acute illness in hospitalized elderly patients.  Historically, delirium was accepted as a harmless process, however, data collected over the past 15 years has shown that this clinical syndrome is linked to poor clinical outcomes and should be regarded as a marker for severe illness and mortality.  In North America, delirium complicates the hospital stays of approx. 20% of patients, 65 years of age and older.  More concerning, is the evidence that the one year mortality rate associated with cases of delirium in the elderly, is 35-40%.  Current studies investigating delirium and its outcomes suggest that the development of delirium in the hospitalized elderly initiates a cascade of events that culminate in the loss of a patients independence, increased risk for morbidity and mortality, and increased health care costs due to longer hospital stays, rehabilitation, need for formal home health care, or long-term institutionalized care.  Despite this evidence, it is estimated that only 40% of clinicians routinely screen delirium in hospitalized elderly patients. Slide: Diagnostic Criteria for Delirium  Currently, the DSM-IV defines delirium by the presence of disturbed consciousness and a change in cognition or the development of a perceptual disturbance that is not better accounted for by a pre-existing, established or evolving dementia.  This disturbance in consciousness must develop over a short period of time and should fluctuate over the course of the day.  Moreover, there must be evidence from clinical history, physical examination and/or lab findings that the disturbance is caused by the physiological consequences of a medical condition. Slide: Clinical Features of Delirium  Introduction: Characteristics of Delirium o In addition to the core symptoms outlined by the DSM-IV, the clinical features shown are also hallmark characteristics of delirium.  Acute Onset: o Occurs abruptly, usually over a period of hours or days. o Reliable information often needed to ascertain the time course of onset.  Fluctuating Course: o Symptoms tend to come and go or increase and decrease in severity over a 24-hour period o Characteristic lucid intervals  Inattention: o Difficulty focusing, sustaining, and shifting attention o Difficulty maintaining conversation or following commands  Disorganized Thinking: o Manifested by disorganized or incoherent speech o Rambling or irrelevant conversation or an unclear or illogical flow of ideas  Altered LOC: o Clouding of consciousness, with reduced clarity of awareness of the environment  Cognitive Deficits: o Typically global or multiple deficits in cognition, including disorientation, memory deficits, and language impairment  Perceptual Disturbances: o Illusions or hallucinations in about 30 percent of patients  Psychomotor Disturbances: o Psychomotor variants of delirium o Hyperactive: marked by agitation and vigilance o Hypoactive: marked by lethargy, with a markedly decrease level of motor activity o Mixed  Altered Sleep-Wake Cycles: o Characteristic sleep-cycle disturbances o Typically daytime drowsiness, night-time insomnia, fragmented sleep, anxiety, depression, irritability, apathy, anger, or euphoria  Emotional Disturbances: o Common o Manifested by intermittent and labile symptoms of fear, paranoia, anxiety, depression, irritability, apathy, anger, or euphoria Slide: Delirium, Dementia & Depression  While reviewing the clinical features of delirium listed in the previous slide, you may have noticed that many of the symptoms observed in patients with delirium are also observed in patients with other neuro-psychiatric diseases or medical illnesses.  This likely represents another reason as to why patients with delirium may be difficult to identify, especially to an inexperienced health care worker.  Consequently, it is crucial that the health care team perform both a careful and detailed history and physical examination of the patient to distinguish between delirium and other types of mental illness or dementia.  As discussed, in cases of delirium, the onset of altered consciousness, cognitive disturbances or hallucinations, is typically acute and presents in the context of mental illness, surgery, or medication change.  To the untrained eye, these features can sometimes be mistaken for a psychotic disorder, especially when auditory or visual hallucinations predominate.  In such cases, it is important to remember that schizophrenia tends to have a gradual onset and appears in late adolescence and early adulthood; it is also preceded by a phase of social isolation that lasts weeks to months.  Moreover, disorientation and fluctuations in LOC are rare in schizophrenia but are a hallmark feature of delirium.  Delirium may also be mistaken for dementia; in patients with dementia the LOC is typically intact and inattention is either absent or mild when compared to other cognitive deficits.  Patients with dementia rarely exhibit fluctuations in their cognitive function, another distinguishing feature between dementia and delirium.  Finally, delirium may also be mistaken for depression, especially when the patient’s symptoms are hypoactive in nature.  Unlike delirium, depression has a more gradual onset of psychomotor slowing and the cognitive deficits tend to reflect disinterest rather than disorientation commonly seen in patients with delirium. Slide: Types of Delirium  Adding to its complexity, delirium exists in three different subtypes: hyperactive, hypoactive and mixed subtypes.  Hyperactive delirium is often characterized by symptoms of restlessness, constant movement and agitation, insomnia, hyper-vigilance, irritability, distractibility, rapid speech, uncooperativeness, and wandering behaviour are also observed.  Given these features, the hyperactive subtype of delirium is often mistaken schizophrenia, bipolar disorder, or agitated dementia.  In contrast, a slowing or lack of movement, paucity of speech, with or without prompting, and unresponsiveness characterize hypoactive delirium.  Apathy and decreased alertness are also typical in patients with the hypoactive subtype of delirium.  Not surprisingly, this is the subtype most often mistaken for depression.  The hypoactive subtype of delirium is more common in the elderly with more than 50% of hospitalized patients presenting with a hypoactive form of the syndrome.  Due to its almost silent nature, this form is the most difficult to identify especially if the patients baseline has not been established.  The mixed subtype is characterized by alternating hyperactive and hypoactive states  Of the three, those with severe hypoactive delirium have the lowest 6-month survival rate.  This may be because those with hyperactive delirium are more likely to be referred to psychiatrists and receive appropriate therapy or interventions due to the more disruptive and potentially self-harming nature of the subtype.  In contrast, hypoactive delirium may be mistaken for compliance, fatigue or simply behaviours incorrectly ascribed to old age. Slide: Screening for Dementia  Since the vast majority of elderly patients fall into the hypoactive delirium subtype, the risk of not identifying a patient with delirium is high.  Given that unmanaged delirium is associated with a significant risk of mortality in the first year, the use of effective screening tools for the diagnosis of delirium is critical.  The confusion assessment method instrument (CAM) has been widely accepted as the most useful scale for diagnosing delirium.  This screening tool diagnoses the delirious state by a yes or no answer to a four-point algorithm based on the DSM-IV criteria.  Proper use of this instrument has the potential to enhance the detection of delirium in hospital settings and reduce the number of delirious patients who go undiagnosed and untreated.  For those patients that are intubated or ventilated, this scale has been adapted so the direct communication is not required.  This is called the CAM-ICU.  While the CAM is an excellent means by which to diagnose delirium, it is not able to rate symptom severity, such that the delirium rate scale is often use to rate symptom severity, follow the course of the syndrome, and assess that patient symptoms are improving with interventions and treatment.  Introduction: The questions associated with the CAM Instrument are listed under the bullets below. For most questions, a “yes” or “no” answer by the health care professional is all that is required.  Acute Onset: o 1) Is there evidence of an acute change in mental status from the client’s baseline?  Inattention: o 2a) Did the client have difficulty focusing attention, for example, being easily distractible, or having difficulty keeping track of what was being said? [ ] not present at any time during the interview; [ ] present at some point during the interview, but in mild form; [ ] present at some time during the interview, in marked form; [ ] uncertain. o 2b) (If present or abnormal) Did this behaviour fluctuate during the interview, that is, tend to come and go or increase and decrease in severity? [ ] Yes; [ ] No; [ ] Uncertain; [ ] Not applicable. o 2c) (If present or abnormal) please describe this behaviour.  Disorganized Thinking: o 3) Was the client’s thinking disorganized or incoherent, such as rambling or irrelevant conversation, unclear or illogical flow of ideas, or unpredictable switching from subject to subject?  Altered LOC: o 4) Overall, how would you rate this client’s level of consciousness? [ ] Alert (normal); [ ] Vigilant (hyper alert, overly sensitive to environmental stimuli, startled very easily); [ ] Lethargic (drowsy, easily aroused); [ ] Stupor (difficult to arouse); [ ] Coma (unarousable); [ ] Uncertain.  Disorientation: o 5) Was the client disoriented at any time during the interview, such as thinking that he or she was somewhere other than the hospital, using the wrong bed, or misjudging the time of day?  Memory Impairment: o 6) Did the client demonstrate any memory problems during the interview, such as inability to remember events in the hospital or difficulty remembering instructions?  Perceptual Disturbances: o 7) Did the client have any evidence of perceptual disturbances, for example, hallucinations, illusions, or misinterpretations (such as thinking something was moving when it was not)?  Psychomotor Agitation and Retardation: o Psychomotor agitation  8) Part 1 – At any time during the interview, did the client have an unusually increased level of motor activity, such as restlessness, picking bedclothes, tapping fingers, or making frequent sudden changes in position? o Psychomotor retardation  8) Part 2 – At any time during the interview, did the client have any unusually decreased level of motor activity, such as sluggishness, staring into space, staying in one position for a long time, or moving very slowly?  Altered Sleep-Wake Cycle: o 9) Did the client have evidence of disturbance of the sleep-wake cycle, such as extensive daytime sleepiness with insomnia at night?  Scoring: To have a positive CAM result, the client must have: o 1) Presence of acute onset and fluctuating course AND o 2) Inattention AND EITHER o 3) Disorganized thinking OR o 4) Altered LOC. Slide: Causes of Delirium  Delirium is rarely caused by a single factor, rather, it is multifactorial, involves a complex interaction between the vulnerable patient and their exposure to precipitating factors.  Predisposing factors include any baseline characteristic present at the time of admission that is patient dependent.  Predisposing factors make the patient vulnerable to delirium and thus be considered predictive of those at risk of developing the syndrome.  In contrast, precipitating factors refer to any noxious insults or factors related to hospitalization that contribute to a patient’s risk of developing delirium.  In 1993 and 1996, (Name?) et al., showed that the effects of baseline and precipitating factors on the risk for developing delirium are cumulative.  Specifically, they showed that the presence of 3 or more delirium risk factors increases the odds that an individual will develop delirium by 60%.  In light of this evidence, it is unlikely that addressing only one risk factor would result delirium in an elderly hospitalized patient.  Consequently, all risk factors, predisposing and precipitating, should be addressed.  Fortunately, most of the risk factors outlined in these two tables are modifiable and amenable to intervention.  We will discuss the different types of interventions used to prevent and manage delirium later on in the module.  Predisposing Factors: o Baseline characteristics present at the time of admission (patient dependent).  Demographic Characteristics: o Age of 65 years or older; o Male sex  Cognitive Status: o Dementia; o Cognitive impairment – related to a 2.82 times increased risk for delirium; o History of delirium; depression.  Functional Status: o Functional dependence; o Immobility; o Low level of activity; o History of falls.  Sensory Impairment: o Visual impairment – relate to a 3.51 times increased risk for delirium; o Hearing impairment.  Decreased Oral Intake: o Dehydration – related to a 2.02 times increased risk for delirium; o Malnutrition.  Drugs: o Treatment with multiple psychoactive drugs; o Treatment with many drugs; o Alcohol abuse.  Coexisting Medical Conditions: o Severe illness – related to a 3.49 times increased risk for delirium; o Multiple coexisting conditions; o Chronic renal or hepatic disease; o History of stroke; o Neurologic disease; o Metabolic derangements; o Fracture of trauma; o Terminal illness; o Infection with HIV.  Precipitating Factors: o Noxious insults or actors related to hospitalization (environment/illness dependent).  Drugs: o Sedative hypnotics; o Narcotics; o Anticholinergic drugs; o Treatment with multiple drugs – related to a 2.9 times increased risk for delirium; o Alcohol or drug withdrawal.  Primary Neurologic Disease: o Stroke, particularly non-dominant hemispheric; o Intracranial bleeding; o Meningitis or encephalitis.  Incurrent Illnesses: o Infections; o Latrogenic complications; o Severe acute illness; o Hypoxia; o Shock; o Fever or hypothermia; o Anemia; o Dehydration; o Poor nutritional status; o Low serum albumin level – related to a 4 times increased risk for delirium; o Metabolic derangements (e.g. electrolyte, glucose, acid-base).  Surgery: o Orthopedic surgery; o Cardiac surgery; o Prolonged cardiopulmonary bypass; o Noncardiac surgery.  Environmental: o Admission to an intensive care unit; o Use of physical restraints – related to a 4.4 times increased risk for delirium; o Use of bladder catheter – related to a 2.4 times increased risk for delirium; o Use of multiple procedures; o Pain; o Emotional stress.  Prolonged sleep deprivation Slide: Causes of Delirium: Predisposing and Precipitating Factors  As discussed, it is the interrelationship between predisposing and precipitating factors that puts a patient at risk for developing delirium.  While each factor has its own independent effect, the synergy between the vulnerable patient and their exposure to noxious stimuli represents a strong predictive model of which most hospitalized patients are at most risk for delirium.  Based on the model outlined on this slide, patients who are highly vulnerable to delirium, such as those with dementia, will develop delirium after exposure to a minor insult, such as a single dose of a sedative drug.  In contrast, in patients who are not predisposed to delirium, the condition will only manifest after exposure to a number of noxious insults such as general anaesthesia, major surgery, and multiple psychoactive medications.  Taken together, this information can be used to predict which patients are at high or low risk for during the first 9 days of their hospital stay.  With this information in hand, interventions for the prevention of delirium can then be targeted to those at risk for delirium. Slide: Multifactoral Model of Delirium  As discussed, a wide variety of factors or noxious insults can precipitate delirium.  Similarly, a wide variety of factors can influence a patient’s vulnerability to developing delirium in response to a noxious stimulus.  For example, in elderly patients, age is a predisposing factor.  However, for young to middle aged adults, age is a protective factor.  Similarly, poor cognitive function, even full blown dementia, is a predisposing factor for delirium, whereas healthy cognitive function or cognitive reserve reduces a patients risk for delirium by exerting a protective effect.  The same can be said for sensation; good vision and hearing are protective factors against delirium.  While hearing or visual impairments increase a patients risk for developing delirium, especially in a hospital setting.  Not surprisingly, overall health influences the risk of developing delirium.  Those that are healthy and fit are at reduced risk for developing delirium in response to a noxious stimulus than those who are of poorer health and weaker functional status. Slide: Pathophysiology of Delirium  Unfortunat
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