Table 16.8-4. Common causes of delirium


Investigations to consider

Treatment suggestions


All settings: UTI, pneumonia, abdominal, cellulitis, skin ulcers, meningitis

ICU: Venous catheter-associated infection, sepsis

Surgical: Wound and surgical site infections

Culture and image appropriately. Asymptomatic bacteriuria is common in older people and positive urine culture alone does not indicate UTI. Look for other causes of delirium

Appropriate use of empiric antibiotics with adjustment based on culture and sensitivity

Medication changes (new additions or withdrawal)

Medication reconciliation, pill count

Either taper/stop offending medications or treat medication withdrawal accordingly

Alcohol withdrawal

Alcohol level, anion gap, osmolar gap

Treat with benzodiazepines, thiamine, and use CIWA to guide management


Pain scale, eg, PAINAD in those with cognitive impairment

Appropriate pain management with acetaminophen and low-dose opioid medications (eg, hydromorphone). Consider peripheral nerve block or adjunct pain management strategies as appropriate

Metabolic abnormality (eg, hypercalcemia, hyponatremia, hypernatremia)

Blood test including sodium and calcium

Determine cause and correct as indicated

Urinary retention

Bedside bladder US to determine PVR. Given the prevalence of urinary retention in the elderly, we typically check PVR in all cases of delirium.

Urinary catheter for obstruction relief, UTI testing/treatment, urologic consultation if needed


Surgical: Ileus

Abdominal radiographs if indicated

Treatment of constipation


ICU: Ventilatory failure, ventilator-associated pneumonia

Chest radiographs, arterial blood gas, ventilation settings

Treat underlying cause (eg, COPD, heart failure, pulmonary embolism, pneumonia, aspiration)

Serotonin syndrome

Medication review

Stop offending medications and treat with benzodiazepines

Hepatic encephalopathy

Ammonia level in appropriate situations

Lactulose or polyethylene glycol, treatment underlying cause

Uremic encephalopathy

Creatinine and urea

Consider dialysis

Subdural hematoma, intracranial hemorrhage, stroke

Neurologic deficits should prompt urgent CT or MRI of the head. Cardiac and vascular surgeries have particularly high risk for postoperative stroke

Initiate ischemic or hemorrhagic stroke management. Neurosurgical consultation for CNS bleeding

Postoperative complications

Thorough history and physical exam looking for anastomotic leak, DVT, fluid overload, hematoma

Treat causes

Excess sedation (in ICU)

Validated tools (eg, Richmond Agitation-Sedation scale) should be used to assess depth of sedation

Avoid excess sedation

Nonconvulsive status epilepticus

In patients with persistent decreased level of consciousness not explained by structural cause EEG should be performed to exclude nonconvulsive status epilepticus

Treatment of seizure with neurologic consultation


Sometimes an unwitnessed fall leads to fracture or concussion that is manifested by delirium. Thorough physical examination is critical. Imaging of injured areas can be considered

Treat as per injury

CIWA, Clinical Institute Withdrawal Assessment; CNS, central nervous system; COPD, chronic obstructive pulmonary disease; CT, computed tomography; DVT, deep venous thrombosis; EEG, electroencephalography; ICU, intensive care unit; MRI, magnetic resonance imaging; PVR, postvoid residual volume; US, ultrasonography; UTI, urinary tract infection.