Delirium
Exam Tips
- In OSCEs, diagnose delirium by proving acute onset + fluctuation + inattention, then present likely precipitants systematically (infection, drugs, metabolic, retention/constipation, pain).
- Always seek collateral history to establish baseline cognition and function; this is often the discriminating step versus dementia.
- Hypoactive delirium is common and easily missed; a quiet withdrawn patient with new drowsiness is delirium until proven otherwise.
- State safety priorities explicitly: 1:1 supervision if needed, falls prevention, avoid restraints where possible, and rapid treatment of reversible causes.
- Before haloperidol, mention contraindications (Parkinson's/Lewy body dementia, prolonged QTc) and need for ECG/electrolyte review.
- Image memory aid: see a standard geriatrics textbook figure of the vulnerability-precipitant model (predisposition on one axis, insult severity on the other) to explain why minor insults can trigger delirium in frail patients.
Definition
Delirium is an acute, fluctuating neuropsychiatric syndrome caused by global cerebral dysfunction (acute encephalopathy), with prominent disturbance of attention and awareness plus cognitive or perceptual change. It develops over hours to days, usually on a background of vulnerability (for example frailty or dementia) with one or more acute precipitants such as infection, drugs, metabolic disturbance, or pain.
Pathophysiology
Delirium is multifactorial and best explained by the interaction of baseline vulnerability and acute physiological stressors. Proposed mechanisms include reduced cholinergic transmission, relative dopaminergic excess, neuroinflammation (peripheral cytokines disrupting blood-brain signalling), impaired cerebral oxidative metabolism, circadian dysregulation, and network disconnectivity in attention/executive systems. These processes produce fluctuating inattention, altered arousal, and disorganised thinking, with hypoactive, hyperactive, or mixed motor phenotypes.
Risk Factors
- Age over 65 years
- Pre-existing cognitive impairment or dementia
- Frailty and multiple comorbidities (for example stroke, heart failure, COPD)
- Recent surgery or hip fracture
- Polypharmacy and high-risk medicines (opioids, benzodiazepines, anticholinergics, corticosteroids, some antihypertensives/antiarrhythmics)
- Alcohol excess or withdrawal history
- Visual or hearing impairment
- Functional dependence, immobility, or physical restraint
- Malnutrition or dehydration
- Terminal illness/palliative phase
Clinical Features
Symptoms
- Acute onset confusion with fluctuating severity (often worse at night)
- Reduced attention (cannot sustain or shift focus)
- Memory and language problems (poor recall, word-finding difficulty)
- Disorganised thinking (rambling, illogical flow)
- Perceptual disturbance (visual hallucinations, misperceptions, paranoid ideas)
- Sleep-wake disturbance (daytime drowsiness, night-time insomnia, reversal)
- Emotional lability (anxiety, fear, irritability, apathy, low mood)
Signs
- Altered level of consciousness from hypervigilance to drowsiness
- Inattention on bedside tests (for example months backwards/digit span errors)
- Disorientation to time/place and fluctuating cognition during assessment
- Hyperactive signs: agitation, wandering, restlessness
- Hypoactive signs: reduced movement, withdrawn behaviour, reduced speech
- Falls, poor oral intake, and new functional decline as early warning signs
- Clinical clues to precipitant (fever, urinary retention, constipation, hypoxia, dehydration)
Investigations
Management
Lifestyle Modifications
- Treat the underlying cause(s) urgently (infection, hypoxia, metabolic disturbance, retention, constipation, pain, withdrawal states)
- Deliver a multicomponent non-pharmacological bundle: orientation cues (clock/calendar), regular reorientation, family/carer presence, calm lighting/noise control
- Optimise hydration and nutrition with assisted oral intake where needed
- Correct sensory deficits (ensure glasses/hearing aids are available and functioning)
- Promote sleep hygiene (reduce nighttime interruptions, daytime mobilisation, avoid unnecessary sedatives)
- Early mobilisation, pressure-area care, falls prevention, and minimisation of lines/catheters/restraints
- Medication review: stop or reduce non-essential deliriogenic drugs and simplify regimens
Pharmacological Treatment
Antipsychotic (short-term, only if severe distress or immediate risk after non-drug measures fail)
- Haloperidol 0.5 mg oral initially (or 0.5 mg IM if oral not possible), then 0.5 mg every 2-4 hours if required; use the lowest effective dose for the shortest duration
Avoid in Parkinson's disease and Lewy body dementia; check ECG/QTc and correct K+/Mg2+ before use; caution in cardiovascular disease and with other QT-prolonging drugs; monitor for extrapyramidal effects, oversedation, and aspiration risk.
Benzodiazepine (specific indications)
- Lorazepam 0.5-1 mg oral/IM, repeated cautiously according to response
Reserve for alcohol-withdrawal delirium or when antipsychotics are contraindicated; may worsen non-withdrawal delirium, cause respiratory depression, falls, and paradoxical agitation (especially older adults).
Cause-directed pharmacotherapy
- Paracetamol 1 g oral/IV every 4-6 hours (max 4 g/day; lower max in low body weight/frailty/liver disease)
- Empirical antimicrobials according to local sepsis/source guidelines (for example amoxicillin 500 mg to 1 g three times daily for susceptible chest sources, adjusted for renal function and allergy status)
Do not use antipsychotics as routine treatment for delirium itself; prescribe only for clear indication and review daily for de-escalation.
Complications
- Increased short- and medium-term mortality
- Longer hospital stay and higher risk of hospital-acquired infection
- Falls, pressure ulcers, incontinence, and malnutrition
- Functional decline and loss of independence
- Increased risk of care-home admission and hospital readmission
- Persistent delirium after discharge
- Accelerated cognitive decline and higher long-term dementia risk
- Significant psychological distress for patients and carers
Prognosis
Course is fluctuating: some patients recover within days, but recovery may take weeks to months, especially in older or frail inpatients. Poorer outcomes are linked to pre-existing dementia, hypoactive subtype, greater severity/duration, hypoxic illness, visual impairment, and frailty. Mortality risk remains elevated for months after discharge, and cognitive/functional decline may persist.
Sources & References
💊BNF Drug References(1)
- Haloperidol[management.pharmacological]
✅NICE Guidelines(1)
- Delirium[overview]
📖Textbook References(4)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 284)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1055, 1056)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1056, 1057)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 283, 284)[context]