How should I evaluate a patient in the emergency department who presents with an acute change in mental status suggestive of delirium?

Delirium Workup in the Emergency Department

Immediate Systematic Screening

Use the Confusion Assessment Method (CAM) or Brief CAM (B-CAM) to objectively diagnose delirium rather than relying on clinical gestalt alone, as bedside clinicians miss delirium in the majority of cases without validated screening tools. 1, 2

• Screen every older adult presenting with acute mental status changes, as 10-35% have delirium on ED arrival but it goes unrecognized in approximately 80% of cases 3
• Document four cardinal features: (1) acute onset with fluctuating course, (2) inattention (test by asking patient to recite months backwards or perform serial 7s), (3) altered level of consciousness, and (4) disorganized thinking 1, 4
• Obtain detailed timeline from a knowledgeable informant about when confusion started and baseline cognitive function, as delirium develops over hours to days versus months to years for dementia 1, 4
• Actively look for hypoactive delirium (lethargy, reduced responsiveness) as this is the most commonly missed subtype and carries higher mortality than hyperactive delirium 4, 1

Essential Laboratory Testing

Order targeted laboratory tests based on clinical evaluation rather than an extensive routine battery, focusing on the most common precipitants. 1

• Complete blood count, comprehensive metabolic panel (including glucose, electrolytes, renal function), and urinalysis are essential first-line tests 1
• Point-of-care glucose and vital signs including oxygen saturation should be obtained immediately 4
• Thyroid function tests when clinically indicated 1
• Infection is the most common precipitating factor—urinary tract infections and pneumonia account for the majority of cases 5, 1

Medication Review

Review ALL current medications with special attention to recent additions or dose changes, as polypharmacy and high-risk medications are frequent culprits. 1

• Focus on anticholinergic drugs, sedatives, narcotics, vasodilators, diuretics, and antipsychotics 1
• Calculate anticholinergic burden and assess for polypharmacy effects 1
• Assess for alcohol use and risk of withdrawal syndrome, as delirium tremens typically peaks 3-5 days after cessation and requires immediate benzodiazepine treatment 6

Selective Neuroimaging

Neuroimaging should be selective and guided by specific clinical features rather than routine for all delirium cases. 5, 1

Indications for CT head without contrast:

• Focal neurological deficits 5, 1
• History of recent head trauma or falls 5, 1
• New onset seizures 5, 1
• Signs of increased intracranial pressure 1
• Unexplained altered mental status despite initial workup 1
• Anticoagulation use 5

When imaging is NOT routinely indicated:

• Delirium with clear precipitant (infection, medication, metabolic) and no focal findings 5
• Intoxicated patients may be observed for symptomatic improvement before imaging, as this is safe practice and prevents unnecessary CT in a large percentage of cases 5

MRI considerations:

• Reserve MRI as second-line when CT is unrevealing but occult pathology suspected (small infarcts, encephalitis, subtle SAH) 5
• Consider MRI first-line only for stable patients with suspected CNS malignancy, inflammatory disorder, or CNS infection 5

Additional Diagnostic Studies

Obtain an electrocardiogram to assess for myocardial ischemia or arrhythmias, and chest radiography to evaluate for pneumonia. 1

• ECG is essential as acute myocardial infarction can present as delirium 1
• Chest X-ray targets pneumonia, the second most common infectious precipitant 1

Common Precipitants to Systematically Evaluate

Two or more coexisting precipitating causes are frequently encountered, so continue searching even after identifying one etiology. 5

• Infections: UTI and pneumonia most common 5, 1
• Metabolic: Hypoglycemia, hyperglycemia, hyponatremia, hypoxia, hypothermia 5
• Medications: Anticholinergics, sedatives, narcotics, polypharmacy 5, 1
• Substance-related: Intoxication or withdrawal (especially alcohol) 5, 6
• Cardiovascular: Acute MI, arrhythmias 1
• Neurologic: Stroke, intracranial hemorrhage, seizure, CNS infection 5
• Environmental: Pain, restraints, stress, sleep deprivation 5

Critical Pitfalls to Avoid

• Never attribute acute confusion to pre-existing dementia without investigating for reversible causes, as delirium commonly occurs superimposed on dementia 1, 4
• Missing delirium doubles mortality risk—early detection is a medical emergency 5, 1
• Failing to recognize hypoactive delirium, which is frequently mistaken for depression or fatigue 1, 4
• Inadequate screening leads to missed diagnosis in the majority of ED cases 1, 3
• Deferring workup in intoxicated patients without establishing a clear improvement timeline 5

Risk Stratification

Patients at highest risk requiring heightened vigilance: 1

• Age ≥65 years
• Pre-existing dementia
• History of hypertension or alcoholism
• High severity of illness at admission
• Recent surgery
• Multiple medications