Pathophysiology
Clinical meaning
Terminal delirium occurs in up to 88% of dying patients and is characterized by acute onset of confusion, fluctuating consciousness, perceptual disturbances, and psychomotor agitation or withdrawal. It represents the final common pathway of multiple organ system failure affecting brain function through neurotransmitter imbalances, metabolic derangements, cerebral hypoxia, and medication effects. Hypoactive delirium (quiet, withdrawn, reduced awareness) is more common but often underdiagnosed, while hyperactive delirium (agitation, hallucinations, restlessness) is more distressing to families. Mixed delirium alternates between both states. Potentially reversible causes include opioid toxicity (switch opioids or reduce dose), medication side effects (anticholinergics, benzodiazepines, corticosteroids), dehydration, urinary retention, constipation (fecal impaction), and infection. However, in the final hours to days of life, delirium is often irreversible as it reflects dying brain function. Management focuses on treating reversible causes when appropriate for the patient's goals, providing safety, using low-dose haloperidol for symptom management, and supporting the family through this distressing symptom.