A 72-year-old woman admitted to the ICU 2 days ago with pneumonia now presents with acute confusion, disorientation, visual hallucinations, and fluctuating consciousness. Her vital signs are unstable (fever 39.2°C, tachycardia, tachypnea). Laboratory tests show elevated inflammatory markers and hypoxia. She was cognitively intact before admission. What is the drug of choice for managing her acute mental status changes?

## Clinical Diagnosis This patient presents with **delirium** superimposed on acute medical illness (pneumonia, hypoxia, infection, ICU setting). ### Diagnostic Features of Delirium **Key Point:** Delirium is characterized by: - Acute onset (hours to days) - Fluctuating course (waxing and waning consciousness) - Disorientation and confusion - Hallucinations (visual > auditory) - Autonomic instability (fever, tachycardia, diaphoresis) - Reversibility with treatment of underlying cause ## Drug of Choice for Delirium **High-Yield:** Haloperidol is the first-line antipsychotic for acute delirium, especially in ICU settings. ### Haloperidol in Delirium Management | Feature | Details | |---------|----------| | **Class** | Typical antipsychotic (dopamine antagonist) | | **Indication** | Acute agitation, hallucinations, confusion in delirium | | **Route** | IV/IM preferred in acute settings (faster onset) | | **Dosing** | 0.5–2 mg IV/IM q30min–q1h; max 20 mg/day | | **Onset** | 15–30 minutes (IV/IM) | | **Advantage** | Minimal sedation; does NOT worsen hypoxia or respiratory depression | | **Adverse effects** | QT prolongation, extrapyramidal side effects, neuroleptic malignant syndrome | **Clinical Pearl:** In ICU delirium, haloperidol is preferred over benzodiazepines because it does NOT suppress respiration or worsen hypoxia. Benzodiazepines are reserved for withdrawal delirium (alcohol, benzodiazepines). ### Atypical Antipsychotics in Delirium - **Olanzapine, risperidone, quetiapine**: second-line alternatives; used when haloperidol contraindicated (QT prolongation, Parkinson's disease). - **Quetiapine**: preferred in Parkinson's disease-related delirium (less extrapyramidal effects). **Mnemonic:** **HAL** = **H**aloperidol for **A**cute **L**oss of consciousness (delirium). Think "HALLUCI" → Haloperidol for Hallucinations in Acute delirium. **Warning:** Do NOT use cholinesterase inhibitors (donepezil) or memantine in acute delirium—they are for chronic dementia, NOT acute reversible confusion. Benzodiazepines alone worsen delirium and increase mortality in ICU patients.