Clinical meaning
ICU delirium is an acute, fluctuating disturbance of consciousness with inattention and disorganized thinking, affecting 60-80% of mechanically ventilated ICU patients and 20-50% of non-ventilated patients. It is independently associated with increased mortality (3.2× in-hospital), prolonged ICU/hospital stay, higher cost, long-term cognitive impairment, and post-ICU PTSD. The pathophysiology is multifactorial: neuroinflammation (systemic inflammation from sepsis/surgery crosses the BBB, activating microglia), neurotransmitter imbalance (dopamine EXCESS + acetylcholine DEFICIT — explains why anticholinergic medications are a major risk factor), disrupted circadian rhythm (loss of melatonin cycling from constant light/noise), impaired cerebral oxidative metabolism, and structural changes (cortical atrophy, white matter disruption). Three motor subtypes exist: hyperactive (agitation, combativeness — 5%, best prognosis, most recognized), hypoactive (lethargy, withdrawal, flat affect — 75%, WORST prognosis, frequently MISSED), and mixed (fluctuating between both — 20%). Screening tools: CAM-ICU (Confusion Assessment Method for ICU — gold standard, sensitivity 93-100%) and ICDSC (Intensive Care Delirium Screening Checklist). Prevention and treatment center on the ABCDEF bundle: Assess/prevent/manage pain, Both SAT (spontaneous awakening trial) and SBT (spontaneous breathing trial), Choice of sedation (avoid benzodiazepines — increase delirium risk 2-4×;...