Mental Health

Delirium

An acute, fluctuating disturbance of attention and awareness caused by an underlying illness, substance effect or withdrawal: treat it as a medical syndrome until the cause is found.

In a nutshell

Think delirium when attention or awareness changes over hours to days and fluctuates. Stabilise, obtain collateral history, use 4AT (CAM-ICU/ICDSC in critical care or recovery), find and treat causes, deliver the prevention/support bundle, and reserve short-term haloperidol for severe distress or safety risk after de-escalation.

Classic presentation

A new fluctuating change in attention, awareness or behaviour, with inattention, altered alertness, disorientation, hallucinations, agitation, withdrawal or sleep disturbance in a patient with an acute illness, medication effect or withdrawal risk.

Key points

Acute onset and fluctuation are clues; inattention and altered alertness matter more than the vague label of confusion.
Hypoactive delirium can look like sleepiness, depression or quiet recovery. Ask for collateral history and assess at-risk patients at least daily.
Use the 4AT when indicators are present; use CAM-ICU or ICDSC in critical care or the postoperative recovery room, then confirm the diagnosis clinically.
Search for multiple precipitants: infection, hypoxia, dehydration, constipation or retention, pain, metabolic disturbance, medicines, intoxication, withdrawal, trauma and neurological disease.
Prevention and treatment are multicomponent: orientation, familiar staff, sensory aids, fluids, nutrition, mobility, pain control, sleep, avoiding unnecessary moves and medication review.
Haloperidol is not first line. If severe distress or safety risk persists after de-escalation, use the lowest clinically appropriate dose for the shortest time, with ECG/electrolyte and extrapyramidal-risk precautions.
If delirium persists, repeat the cause search, reassess cognition for possible dementia and communicate the diagnosis and follow-up plan to primary care.

First-line investigation

Immediate ABCDE and observations, collateral baseline history, 4AT when indicators are present, and targeted tests guided by the suspected reversible cause.

Management

Stabilise and recognise the dangerous branch

Use ABCDE, glucose, observations and focused neurological assessment; escalate for reduced consciousness, hypoxia, shock, sepsis, seizure, poisoning, focal neurology or rapidly worsening risk.^1,2
Take collateral history immediately: establish baseline, onset, fluctuation, medication/substance changes and withdrawal risk.^1,2

Confirm and investigate without over-testing

Use the 4AT when indicators are present; use CAM-ICU or ICDSC in critical care or recovery, then obtain a clinical diagnosis and document it.^1,5
Choose targeted bloods, microbiology, ECG, imaging or other tests from the examination and suspected cause; repeat assessment when the mental state changes.^1,2

Treat causes and deliver the bundle

Correct the precipitant or precipitants: oxygenation, glucose, infection, hydration, pain, constipation, retention, metabolic disturbance, medication toxicity, intoxication or withdrawal and neurological disease.^1,2
Start tailored prevention/support within 24 hours for people at risk: orientation, familiar team, sensory aids, fluids, nutrition, mobility, sleep, pain and avoidance of unnecessary moves.^1,6

Manage distress safely

Use calm communication, reassurance, reorientation and verbal/non-verbal de-escalation first while maintaining safety and dignity.^1,6
Only if severe distress or safety risk persists, consider short-term haloperidol at the lowest clinically appropriate dose; use ECG/electrolyte and extrapyramidal precautions and avoid or seek specialist advice in Parkinson's disease or Lewy body dementia.^1,4

Reassess, communicate and safety-net

If delirium persists, repeat the cause search, review medication and withdrawal, reconsider neurological and other differentials, and assess for possible dementia once the acute state permits.^1,3
Document delirium in the clinical and primary care records, explain recovery and warning signs to family/carers, and provide a named follow-up and return-advice plan.^1,3,2

Exam traps

A patient diagnosed with dementia after an overnight change may have delirium, dementia, or both; manage the acute delirium first.
A normal temperature, one normal observation set or a negative initial test does not exclude delirium or its precipitant.
Do not use a positive 4AT as the whole diagnosis: a clinician with relevant expertise should confirm delirium.
Do not use the 4AT in critical care or the postoperative recovery room when CAM-ICU or ICDSC is the recommended tool.
Quiet withdrawal and reduced movement are hypoactive delirium, not reassurance.
Haloperidol follows failed de-escalation and has important cardiac, electrolyte and extrapyramidal risks; avoid or seek specialist advice in Parkinson's disease and Lewy body dementia.
Persistent delirium requires a renewed search for causes and later cognitive follow-up, not simply a prolonged prescription for sedation.

Illustrations

4AT screening toolLayout of the 4AT tool showing alertness, AMT4 orientation, attention and acute change or fluctuation as the four bedside screening components for delirium.PassFinals · original

Delirium precipitants and prevention bundleA central acute change in attention and awareness surrounded by modifiable precipitant and prevention domains: oxygenation, hydration, infection, pain, medicines, mobility, nutrition, constipation, sensory support, orientation and sleep.PassFinals · original

Hyperactive, hypoactive and mixed deliriumComparison diagram showing agitation and heightened arousal, quiet withdrawal and reduced movement, and fluctuation between both phenotypes, all arising from the same acute delirium syndrome.PassFinals · original

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.