Summary
Epidemiology
Levels of consciousness
- Hyperalert: heightened arousal with increased sensitivity to immediate surroundings. Hyperalert patients can be verbally and physically threatening, restless, and/or aggressive.
- Confused: disoriented; bewildered, and having difficulty following commands.
- Delirious: disoriented; restless, hallucinating, sometimes delusional.
- Somnolent: sleepy, responding to stimuli only with incoherent mumbles or disorganized movements.
- Lethargic: reduced level of alertness with decreased interest in the surrounding environment.
- Obtunded: similar to lethargy; the patient has a lessened interest in the environment, has slowed responses to stimulation, and tends to sleep more than normal with drowsiness in between sleep states.
- Stuporous: profoundly reduced alertness and requiring continuous noxious stimuli for arousal.
- Comatose: state of deep, unarousable, sustained unconsciousness.[6]
Urgent Considerations
Acute neurologic events
Severe systemic infection
- age under 1 year
- age over 75 years
- frailty
- impaired immunity (due to illness or drugs)
- recent surgery or other invasive procedures
- any breach of skin integrity (e.g., cuts, burns)
- intravenous drug misuse
- indwelling lines or catheters
- pregnancy or recent pregnancy.
- Measure lactate level, and remeasure lactate if initial lactate is elevated (>18 mg/dL [>2 mmol/L]).
- Obtain blood cultures before administering antibiotics.
- Administer broad-spectrum antibioticsĀ (with methicillin-resistant Staphylococcus aureus [MRSA] coverage if there is high risk of MRSA) for adults with possible septic shock or a high likelihood for sepsis.
- For adults with sepsis or septic shock at high risk of fungal infection, empiric antifungal therapy should be administered.
- Begin rapid administration of crystalloid fluids for hypotension or lactate level ā„4 mmol/L (ā„36 mg/dL). Consult local protocols.
- Administer vasopressors peripherally if the patient is hypotensive during or after fluid resuscitation to maintain MAP ā„65 mm Hg, rather than delaying initiation until central venous access is secured. Norepinephrine is the vasopressor of choice.
- For adults with sepsis-induced hypoxemic respiratory failure, high-flow nasal oxygen should be given.
Gastrointestinal
Cardiac events
Psychiatric events
Respiratory disorders
Medication effects
Toxidromes
Endocrinopathies
Metabolic abnormalities
Glucose abnormalities
Etiology
Cerebrovascular
Traumatic
Neurologic
Cardiac and pulmonary
Psychiatric
Metabolic
Endocrinologic
Infectious
Gastrointestinal
Exogenous
Differential Diagnosis
Diagnostic Approach
- The Confusion Assessment Method (CAM), the CAM Short Form (CAM-S), and the brief CAM (bCAM) can be used to diagnose delirium, focusing on four cardinal features:[28] [29] [30] [31]
- Acute onset and fluctuating course
- Inattention
- Disorganized thinking
- Altered level of consciousness.
CAM is a well-validated tool for evaluating delirium, with a reported sensitivity of 87% to 100% and specificity of 80% to 100%.[32] CAM is specific for evaluating incident delirium in critically ill older patients (although its sensitivity may be lower than that of some other screening tools), and it is commonly used to determine delirium severity (as are the Delirium Rating Scale [DRS] and the Memorial Delirium Assessment Scale).[33] [34]
- The Observational Scale of Level of Arousal (OSLA) is a bedside evaluation tool, which has a sensitivity of over 90% and a specificity of over 80% for diagnosing delirium in older patients.[35] The evaluation is based on patient observations in four clinical areas: eye contact, eye opening, posture, and movement.
- Alertness: anything less than A on the alert, voice, pain, unresponsive (AVPU) scale
- AMT4: four questions from the Abbreviated Mental Test (age, date of birth, place, and current year)
- Cognition: recite the months backward (December to July only)
- Acute change or fluctuating course.
History
- Previous cognitive status: it is imperative to establish a baseline cognitive and functional status before the onset of symptoms. In most cases, a rough assessment of previous cognitive status can be obtained from the patient's family. A previously obtained assessment of cognition can also be compared with a current screen to determine whether symptoms related to cognitive changes are acute or chronic in nature. The Folstein Mini-Mental State Examination (MMSE) is still the most widely used cognitive screening test.[37] However, it has been increasingly shown in the literature to be poorly sensitive in differentiating mild cognitive impairment from a dementia syndrome, due largely to the MMSE's lack of executive function testing.[38] [39] [40] There are several other tests available, including the 10-minute Montreal Cognitive Assessment Scale (MoCA).[41] [42] [43] Some instruments, such as the Mini-Cog test and Addenbrooke's Cognitive Examination-Revised (ACE-R), have been shown to perform as well as the MMSE in terms of detecting dementia.[40]Ā Existing tools for evaluating delirium superimposed on dementia lack robust evidence to support their utility; however, results obtained with the CAM and CAM-ICU are promising.[44] [45]
- It is noteworthy that fluent aphasia (e.g., Wernicke encephalopathy) can sometimes be mistaken for delirium or AMS, particularly when other neurologic signs are not present. Therefore, short tests for aphasia (e.g., object naming, phrase repetition, following simple commands) should be conducted in differentiating this condition.
- Previous functional status: care should be taken to determine whether the patient has deficiencies in activities of daily living, hearing impairment, or vision impairment.
- Medication usage: medication lists should be carefully scrutinized. Potentially high-risk medications should be discontinued whenever possible. Herbal remedies, nonprescription medications, and illicit substances should also be considered in a medication review.
- Comorbid conditions: particularly neurologic diseases (e.g., stroke, Parkinson disease, dementia), cardiovascular diseases (e.g., myocardial infarction [MI], angina), and a history of renal/metabolic diseases (e.g., hyponatremia, hypernatremia, chronic renal failure).
- Pain levels: the presence of severe pain is often associated with AMS. Chest pain (often described as heavy, or tight) radiating to arms, back, neck, or jaw is typical with MI, although chest pain may be absent in older adults and people with diabetes.
- Alcohol and drug use: alcohol intoxication and withdrawal are frequently associated with AMS.
- Nonspecific irritability: together with typical symptoms of sweating, palpitations, weight loss, may suggest thyrotoxicosis.
- Environmental factors: key issues such as sleep deprivation, multiple procedures or surgery, restraint use, and intensive care stay are associated with delirium and might be causative. Hypothermia may be suspected if there is a recent history of exposure to the cold for a prolonged period of time, or with inadequately warm clothing. This is more common in older adults, or in young children and infants. Alternatively, heat stroke may be suspected following intense exercise under hot, humid conditions.
Physical examination
- Pupillary response: might suggest drug intoxication, drug withdrawal, or stroke.
- Vital signs: may be particularly revealing, either in a toxidrome pattern, such as anticholinergic toxicity (e.g., fever, tachycardia, hypertension), or in a pattern of autonomic dysfunction, as in alcohol withdrawal, although this may be blunted in older people. Bradycardia and hypotension reflect possible myxedema coma or heart block. Bradycardia and hypertension can be signs of elevated intracranial pressure. Tachycardia and hypotension may suggest shock either from cardiogenic or hypovolemic etiologies.
- Fever: may be helpful for distinguishing infection. Hyperthermia (e.g., with heat stroke) is generally associated with core temperatures >104Ā°F (>40Ā°C). Sweating, together with palpitations, weight loss, and irritability, may suggest thyrotoxicosis.
- Core body temperature: lowered to <95Ā°F (<35Ā°C) if hypothermic. Low-reading infrared tympanic membrane thermometers should be used.
- Neck stiffness: meningitis or encephalitis should be considered.
- Lung exam: decreased breath sounds and rales might indicate infection (e.g., pneumonia) or diseases commonly associated with hypoxia such as congestive heart failure (CHF) and COPD.
- Cardiovascular exam: physical findings evident with coronary disease or MI should be evaluated.
- Abdominal exam: might suggest intra-abdominal infection. If the history and physical exam findings suggest constipation, secondary causes need to be ruled out. Features of intestinal obstruction may be present.
- Suprapubic tenderness or palpable bladder: might suggest urinary tract infection (UTI) or obstruction.
- Hip tenderness: might suggest occult hip fracture, a frequently missed trigger for delirium in frail older patients, particularly if they are bed-bound.
- Neurologic findings: focal findings might suggest stroke or neurologic insult. The investigation should include cranial nerve testing (including visual fields); motor exam (to assess focality and possible parkinsonism); sensory (often difficult in a patient with AMS), cerebellar, and verbal abilities; and gait.
Investigations
- Plasma glucose should be the first test in any patient presenting with AMS; it is quick and easy to perform, and abnormalities are readily treatable. If the test is not immediately available, empiric glucose should be given.
- CBC to confirm suspected anemia and help in the diagnosis of infection.
- Chemistry panel, including glucose levels, to rule out metabolic disturbances.
- Thyroid function tests if thyrotoxicosis or myxedema coma is suspected.
- Urinalysis to rule out UTI.
- Chest x-ray to help detect pneumonia, CHF, or other potential causes of hypoxia.
- Drug levels in patients on digoxin, lithium, quinidine, and alcohol (if a history of alcohol abuse is suspected).
- ECG and cardiac enzymes to rule out MI.[6]
- Arterial blood gas or pulse oximetry to evaluate for hypoxia and lactate, commonly found in sepsis, or hypercapnia.
- If liver dysfunction is suspected, liver function tests, including bilirubin, are warranted; coagulation studies may be abnormal. Plasma ammonia measurement should be performed in patients with delirium/encephalopathy and liver disease.[46]
- If infection is suspected, blood and urine culture should be obtained. Lumbar puncture is recommended in the presence of nuchal rigidity and fever, or if encephalitis is suspected.
- If a hip fracture is suspected as a cause of AMS (e.g., with a history of a fall and age above 65 years), a pelvic x-ray and consideration of a hip computed tomography (CT) scan (e.g., in patients with persistent pain, concerning exam findings, no obvious fracture visible on x-ray) or bone scan may be helpful.
- Neurologic imaging (CT and/or magnetic resonance imaging).
- Holter monitor, exercise testing, and/or cardiac electrophysiology studies to assess for arrhythmias.
- Coronary angiography to rule out ischemic heart disease.
- Echocardiography to assess for cardiac failure and cardiomyopathy.
- B-type natriuretic peptide to assess for cardiac failure.
- CT pulmonary angiogram or ventilation-perfusion scan to evaluate for pulmonary embolism as a cause of hypoxia.
- Glomerular filtration rate may be useful in uremia.
- Abdominal imaging and/or endoscopy if abdominal pathology such as acute appendicitis or bowel ischemia is suspected.
- EEG to rule out seizure activity and encephalopathy. Diffuse slowing of the EEG may be helpful in highlighting delirium.[47]
- A therapeutic trial of parenteral thiamine if Wernicke encephalopathy is suspected.
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