Definition & core features

• Acute onset and fluctuating course.
• Disturbance in attention (reduced ability to focus) and awareness.
• Cognitive changes (memory, orientation, language, perception) not better explained by a pre-existing neurocognitive disorder.
• Evidence that disturbance is a direct physiological consequence of another medical condition, substance intoxication/withdrawal, toxin exposure, or multiple causes.

Types and presentations

• Hyperactive delirium: agitation, restlessness, hallucinations, aggression — easier to detect.
• Hypoactive delirium: lethargy, reduced motor activity, withdrawal — frequently missed and associated with poorer outcomes.
• Mixed delirium: fluctuates between hyper- and hypoactive features.
• Persistent or prolonged delirium: lasts weeks to months, often in older, frail patients or when underlying causes are unresolved.

Common precipitants

• Infections (UTI, pneumonia, sepsis).
• Metabolic disturbances (electrolyte imbalance, hypoglycaemia, hepatic/renal failure).
• Hypoxia, hypotension, acute cardiac events.
• Medication effects (anticholinergics, opioids, benzodiazepines, sedatives).
• Withdrawal (alcohol, benzodiazepines, opioids).
• Acute neurological events (stroke, intracranial haemorrhage, seizures).
• Surgical procedures, especially in older adults (post‑operative delirium).

Assessment — practical tools

1. Use brief validated tools: 4AT (rapid), CAM (Confusion Assessment Method) for systematic assessment.
2. Assess baseline cognitive function and gather collateral history from family/caregivers.
3. Evaluate for delirium severity and subtype (hypo vs hyperactive) and document fluctuation pattern.
4. Screen for pain, sensory impairment, bowel/bladder issues and sleep disruption contributing to delirium.
5. Consider capacity assessment for immediate decisions if patient lacks decision-making ability.

Investigations — focused and timely

• Basic tests: CBC, electrolytes, renal & liver function, glucose, calcium, magnesium, phosphate, TFTs.
• Oxygen saturation and arterial blood gas if respiratory compromise suspected.
• Infection screen: urine microscopy/culture, blood cultures, chest x‑ray.
• ECG for arrhythmia or QTc changes if using antipsychotics.
• Neuroimaging (CT/MRI) when focal neurological signs, head trauma, prolonged or atypical delirium.
• EEG if seizures or non-convulsive status epilepticus suspected.
• Consider toxicology, drug levels and pregnancy test when relevant.

Management framework — ABC + STEPWISE

Stabilise the patient, identify and treat underlying causes, and use non-pharmacological measures as first-line. Pharmacology is reserved for severe distress or safety risks.

Stabilise (ABC)

• Address airway, breathing, circulation; give oxygen for hypoxia; correct hypotension and hypoglycaemia promptly.

STEPWISE (Treat causes, Environment, Pharmacology, Prevention)

• Treat causes: antibiotics for infection, fluids/electrolyte correction, manage withdrawal, adjust offending medications.
• Environment: reorientation, ensure glasses/hearing aids, family presence, reduce noise and optimize day/night cues.
• Pharmacology: reserve for severe agitation, psychosis or risk. Low-dose antipsychotics (e.g., haloperidol, quetiapine) guided by ECG and risk profile. Avoid benzodiazepines except in alcohol/benzodiazepine withdrawal.
• Prevention: proactive measures in at-risk patients: avoid polypharmacy, ensure hydration, early mobilisation, sleep protocols, and minimise unnecessary catheter use.

Pharmacological considerations

• Haloperidol — often used for severe agitation; monitor QTc and extrapyramidal side effects.
• Quetiapine/olanzapine — alternatives with lower EPS risk but metabolic/anticholinergic effects to consider.
• Benzodiazepines — use only in withdrawal states or specific indications; they may worsen delirium otherwise.
• Melatonin/melatonin agonists — may help with sleep regulation and prevention in some settings.

Prevention strategies

• Identification of high-risk patients on admission (age, dementia, sensory impairment, polypharmacy).
• Implement multicomponent prevention protocols: orientation, sleep promotion, early mobilization, vision/hearing optimisation, hydration and minimising tethers.
• Medication stewardship — reduce or avoid deliriogenic drugs.
• Staff education and delirium pathways for rapid recognition and response.

Key takeaways

• Delirium is common, serious and often reversible — early recognition and treatment of underlying causes are essential.
• Hypoactive delirium is under-recognised and carries poor prognosis if missed.
• Non-pharmacological approaches and prevention bundles reduce incidence and improve outcomes.
• Document findings, communicate clearly with families and arrange follow-up for unresolved symptoms or cognitive concerns.