Delirium: past, present, and future.

Delirium was described by Hippocrates over 2500 years ago and it remains an important clinical problem today. Work continues to improve definition, prevention, diagnosis, and treatment, but relatively young science remains. Delirium affects 12,500,000 patients and costs $152,000,000,000 every year. Up to 80% of mechanically ventilated patients experience delirium, which exists as a spectrum of acute brain organ dysfunction. Multiple theories exist, including contribution from baseline pathology, medications, surgical inflammation, and environment. Biochemical models point to pathophysiology. Delirium remains largely preventable through planning and subgroup identification. Validated objective assessment models aid diagnosis, whereas protocolized multimodal intervention remains best practice. Pharmacotherapy, as chemical restraint, is reserved for cases of potential harm to self or others. Observation obviates mechanical restraint. The contribution of delirium to cognitive decline remains controversial and concerning. As dollars shrink and cost does not, delirium becomes increasingly important. In an aging population of increasing frailty, delirium will contribute increasingly to long-term morbidity and even mortality.