Delirium is common in older emergency department (ED) patients. Although associated with significant morbidity and mortality, it often goes unrecognized. A consistent approach to evaluation of mental status, including use of validated tools, is key to diagnosing delirium. Identification of the precipitating event requires thorough evaluation, including detailed history, medication reconciliation, physical examination, and medical work-up, for causes of delirium. Management is aimed at identifying and treating the underlying cause. Meaningful improvements in delirium care can be achieved when prevention, identification, and management of older delirious ED patients is integrated by physicians and corresponding frameworks implemented at the health system level.
Key points
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Delirium is common and associated with significant morbidity and mortality.
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Evaluate mental status in all older patients presenting to the emergency department; do not rely on gestalt—use a validated tool to assess for delirium.
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Obtain a thorough medication list (including over-the-counter medications), paying special attention to medications with anticholinergic properties.
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Utilize nonpharmacologic measures, such as reorientation and decreasing unfamiliar stimuli, for high-risk individuals to prevent and treat delirium.
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Consider using low-dose antipsychotics in agitated delirious patients who are at imminent risk of harm.
Case
Mrs Penelope Jones, an 86-year-old woman, presents to the emergency department (ED) after falling. She is brought in by ambulance after being found on the floor in her apartment. Her past medical history includes hypertension, hypothyroidism, and remote stroke. Her medications include hydrochlorothiazide, levothyroxine, and clopidogrel.
On assessment, Mrs Jones is asleep in the bed. She rouses to voice and states she tripped on the carpet. She denies hitting her head. Her only complaint is right wrist pain. Further review of systems is unremarkable. Throughout the interview, she is noted to lose focus on the conversation, occasionally closing her eyes and requiring prompting to answer questions. Her physical examination is unremarkable aside from an obviously deformed right wrist. A radiograph is ordered and some collateral history gathered from Mrs Jones’ daughter.
Learning points
Definition of Delirium
The American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) classifies delirium as a minor neurocognitive disorder. To be diagnosed with delirium, a patient must meet the 5 criteria outlined in Table 1 .
| Criteria A | A disturbance in attention (ie, reduced ability to direct, focus, sustain, and shift attention) and awareness (reduced orientation to the environment) |
| Criteria B | The disturbance develops over a short period of 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. |
| Criteria C | An additional disturbance in cognition (eg, memory deficit, disorientation, language, visuospatial ability, or perception) |
| Criteria D | The disturbances in criteria A and C are not better explained by another preexisting, established, or evolving neurocognitive disorder and do not occur in the context of a severely reduced level of arousal, such as coma |
| Criteria E | There is evidence from the history, physical examination, or laboratory findings that the disturbance is a direct physiologic consequence of another medical condition, substance intoxication or withdrawal (ie, due to a drug of abuse or to a medication), or exposure to a toxin, or is due to multiple etiologies. |
Delirium has been described using various phenotypes, including the psychomotor impact, arousal state, and severity. Psychomotor subtypes include hyperactive, hypoactive, or mixed. Hypoactive is the most common, least likely to be identified, and associated with worse outcomes in hospitalized patients. Patients with delirium may exhibit increased, decreased, or normal level of arousal. Delirious older ED patients with normal levels of arousal have an increased risk of six-month mortality. The measurement of delirium severity may be useful to monitor clinical course and treatment response. Increased delirium severity is associated with increased mortality and subsequent cognitive impairment. , ,
Delirium Prevalence in the Emergency Department
Delirium is common in older patients presenting to the ED. Prevalence may be as high as 17%. Literature consistently has shown that health care providers are poor at recognizing delirium in older ED patients despite the development of multiple validated tools to identify delirium over the past two decades. , , A recent study showed that delirium was missed in 84.6% of older ED patients. Up to 28% of patients with undiagnosed delirium are discharged home from the ED, and, for those who are admitted, it remains unrecognized in the majority.
Sequelae of Delirium
Delirium is an acute medical emergency. It has a devasting impact on patients, their families, and the health care system. Delirium in older ED patients is associated with an increase in hospital admission, intensive care unit admission, hospital length of stay, , likelihood of discharge to a higher level of care, and death. , , , , Delirium has been shown to cause significant psychological distress to patients and their families. , Additionally, the economic impact of delirium is huge; in 2011 it was estimated to be greater than $164 billion per year in the United States. ,
Delirium results from acute brain failure; however, its sequelae may have more prolonged consequences than originally thought. There is mounting evidence that it results in adverse long-term outcomes. Delirium has been shown to persist up to twelve months in up to 50% of patients and furthermore is known to be a risk factor for subsequent cognitive , , and functional decline.
Physiology/Pathophysiology of Delirium
Multiple hypotheses have been proposed regarding the pathophysiology of delirium, including neuronal aging; oxidative stress; neuroinflammatory, neuroendocrine, and neurotransmitter dysfunction; and circadian rhythm dysregulation. , The investigation of neurotransmitters and biomarkers that can validate the underlying basis of these theoretic models is an area of rapidly expanding research. Advanced neuroimaging also may have a role to play in identifying structural abnormalities of the brain in patients suffering from delirium. ,
Given the multiple proposed hypotheses, it is likely that delirium is the end result of multiple abnormalities that are unique to that individual, based on predisposing factors and precipitating insults. , The expression of delirium is as unique and variable as the pathophysiologic basis from which it arose in that specific individual.
Predisposing factors and precipitating insults for delirium
Predisposing Factors
Delirium occurs in vulnerable patients who possess underlying predisposing factors and subsequently are exposed to a precipitating insult. There are many underlying risk factors predisposing older patients to delirium development ( Table 2 ). The most common predisposing factor is dementia, which is present in at least half of the patients presenting with delirium.
| Predisposing Factors | Precipitating Insults |
|---|---|
| Dementia Age Premorbid functional impairment Visual or hearing impairment Preexisting psychiatric illness (bipolar disorder, schizophrenia Underlying stroke or seizure disorder Chronic use of medications, for example, narcotics and benzodiazepines Alcohol or drug use disorder | Infections, for example, UTI and pneumonia Medications and toxins Intracranial diseases, for example, stroke, meningitis/encephalitis, seizures, neoplasm, and hypertensive encephalopathy Cardiovascular disease, for example, ACS and CHF Metabolic disorders, for example, electrolyte abnormalities, hepatic and uremic encephalopathy, and thiamine deficiency Endocrine disorders, for example, thyroid disorders and adrenal disorders Dehydration and malnutrition Iatrogenic, for example, prolonged ED stay, restraints, pain |
Precipitating Insults
Precipitating insults are summarized in Table 2 . The resultant delirium may be delayed by 24 hours or more and often is multifactorial. , The most common precipitating insult is infection, accounting for approximately 50% of presentations. , An underlying infection may be missed in older adults because they often present atypically and may lack a fever, leukocytosis, or localizing symptoms.
Medications, whether prescribed or over the counter, are implicated in up to 30% of patients presenting with delirium. , Medications with anticholinergic properties are particularly deliriogenic. , Older adults are more susceptible to adverse drug events due to altered pharmacokinetics and pharmacodynamics; this is compounded by the presence of polypharmacy. Commonly implicated medications are listed in Table 3 . Alcohol use and illicit drug use are relatively common in older adults, and intoxication and withdrawal syndromes should be considered as causes of delirium.
| Antihistamines a | Muscle relaxants |
| Antiemetics | Opioids a |
| Dihydropyridines a | Sedative-hypnotics a |
| Diuretics |
Iatrogenic causes that precipitate delirium, in addition to medications, include prolonged ED length of stay (>10 hours), use of physical restraints, sleep deprivation, undergoing a procedure, and under-treatment of pain. Pain, which may result from an acute medical condition or injury, urinary retention, constipation, or hunger, frequently is undertreated in the geriatric population. Furthermore, eliciting the presence of pain may be challenging in patients with cognitive impairment, necessitating the utilization of a standardized scale, such as the Pain Assessment in Advanced Dementia.
Clinician recognize that Mrs. Jones is vulnerable to delirium given her age and history of stroke. Clinician suspect that the pain from the fracture and the long wait in the ED may increase her risk. Clinician wonder what other elements of the history and physical examination are relevant and whether clinician should order any additional tests.
History
The clinician should use the interview as an opportunity to observe the patient’s mental status. Many patients with altered mental status may deny the existence of a problem, whether due to lack of insight, stoicism, or fear of losing independence. Obtaining collateral history provides the clinician with a better understanding of a patient’s baseline mental status, an appreciation for the time course and progression of the current illness, and clues to the precipitating insult(s). Obtaining an accurate medication list (including over-the-counter medications), in addition to recent changes or the possibility of an overdose, is essential.
Physical examination
General Examination
Apparently normal vital signs should not falsely reassure the emergency practitioner, because fever, tachycardia, and hypotension may be attenuated in older adults despite being critically ill. An accurate respiratory rate should be obtained, because tachypnea is the most sensitive vital sign for infection.
Fully undressing patients is necessary to perform a thorough examination. Subtle signs of trauma should be sought out because history of injury may not be apparent, due to stoicism or elder abuse. A skin examination looking for signs of infection, medication patches, or indwelling catheters is prudent. Localizing signs of infection, such as abdominal tenderness or neck stiffness, may be absent and should not deter the astute emergency physician from pursuing the appropriate diagnosis.
Mental Status Evaluation
Multiple guidelines advocate for the evaluation of mental status in all older patients presenting to the ED to assess for the presence of delirium. A complete mental status evaluation includes assessment of consciousness, perception (such as hallucinations and delusions), and cognition (orientation, attention, memory, executive function, language, and visuospatial ability).
Making the diagnosis
More than twenty delirium screening tools have been developed; however, not all are suitable for the ED. Several tools have been validated in the ED and are summarized in Table 4 . , The Geriatric Emergency Department Guidelines, a research-based and consensus-based best practices report, advocates the use of the Delirium Triage Screen (DTS) and Brief Confusion Assessment Method (bCAM) for mental status evaluation. Flowsheets, training manual, and videos can be accessed at http://eddelirium.org/delirium-assessment/dts/ and http://eddelirium.org/delirium-assessment/bcam/ for the DTS and bCAM, respectively. Their diagnostic characteristics are presented in Table 5 .
| 4AT | Modified CAM for the ED |
| Brief CAM | Month of the year backward test |
| CAM for the intensive care unit | Ottawa 3DY |
| Four-item Abbreviated Mental Test | RASS |
| Test | Sensitivity (95% CI) | Specificity (95% CI) | Negative Likelihood Ratio (95% CI) | Positive Likelihood Ratio (95% CI) |
|---|---|---|---|---|
| DTS | 98.0% (89.5–99.5) | 54.8% (49.6–59.9) | 0.04 (0.01–0.25) | 2.17 (1.92–2.45) |
| bCAM | 84.0% (71.5–91.7) | 95.8% (93.2–97.4) | 0.17 (0.09–0.32) | 19.94 (11.97–33.19) |
The DTS ( Fig. 1 ) is highly sensitive (98%), takes less than twenty seconds to administer, and does not require the use of additional instruments, making it ideal as a screening test to rule out delirium. It is composed of two parts: the Richmond Agitation-Sedation Scale (RASS) and spelling “lunch” backwards. The RASS ( Table 6 ) is a ten-point scale that measures patient arousal. The score is determined by observing a patient’s response to verbal or physical stimulation. If a patient scores anything other than zero, then the patient screens positive for delirium. If the patient is alert and calm (RASS = 0), then the patient is asked to spell the word “lunch” backwards. If the patient is able to do so with only one error or less, then delirium has been ruled out and no further testing is required. If the screen is positive, the diagnosis of delirium should be confirmed with a highly specific formal test for delirium, such as the bCAM.
| Score | Term | Description |
|---|---|---|
| +4 | Combative | Overtly combative or violent; immediate danger to staff |
| +3 | Very agitated | Pulls on or removes tube(s) or catheters) or has aggressive behavior toward staff |
| +2 | Agitated | Frequent nonpurposeful movement or patient-ventilator dyssynchrony |
| + 1 | Restless | Anxious or apprehensive but movements not aggressive or vigorous |
| 0 | Alert and calm | |
| −1 | Drowsy | Not fully alert, but has sustained (more than 10 s) awakening, with eye contact, to voice |
| −2 | Light sedation | Briefly (<10 s) awakens with eye contact to voice |
| −3 | Moderate sedation | Any movement (but no eye contact) to voice |
| −4 | Deep sedation | No response to voice, but any movement to physical stimulation |
| −5 | Unarousable | No response to voice or physical stimulation |
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The bCAM ( Fig. 2 ) was adapted from the confusion assessment method for the intensive care unit and contains the four cardinal features of delirium. Its algorithmic approach, with objective questions to test inattention and disorganized thinking, makes it simple to perform in less than two minutes. Tips on scoring are summarized in Table 7 .
Clinician gather collateral history from Mrs Jones’ daughter, who tells clinician that her mother, whom she last spoke with two days ago, is normally “sharp as a tack.” Evaluating her now, clinician find her confused to place, unable to correctly name the months of the year backwards, and drowsy. Mrs. Jones scores positive on the bCAM. Clinician think she has delirium but clinician are not sure why.
