Delirium

Overview

Delirium (acute confusional state) is an acute, fluctuating syndrome of inattention, disturbed cognition, and altered consciousness. It is not a diagnosis - always find and treat the underlying cause.

Investigations

🥇 First-line

•CAM assessment; urinalysis and MSU; FBC, U&E, LFTs, CRP, glucose, TFTs, calcium; CXR; blood cultures (if sepsis suspected); medication review; stool and fluid balance chart review

🥈 Second-line

•CT head - if new focal neurology, head injury, or no clear precipitant; ECG - if cardiac cause suspected; EEG - if non-convulsive status epilepticus suspected

Differential Diagnosis

Delirium vs dementia vs depression

Feature	Delirium	Dementia	Depression
Onset	Hours to days	Months to years	Weeks to months
Consciousness	Clouded, fluctuating	Alert (normal)	Alert (normal)
Course	Fluctuating	Progressive, stable day-to-day	Persistent low mood

🎯

Pre-existing dementia is a major risk factor for delirium - the two commonly coexist. An acute deterioration in a known dementia patient = delirium until proven otherwise.

Management

Step 1 · Always first

1. 1Identify and treat the precipitant - antibiotics for infection, laxatives/suppositories for constipation, catheterisation for urinary retention, IV fluids for dehydration, analgesia for pain, stop offending medications

↓

Step 2 · Non-pharmacological

1. 1Reorientation - clock, calendar, familiar faces, consistent nursing staff
2. 2Environmental optimisation - good daytime lighting, quiet at night, hearing aids and glasses in place, encourage mobilisation, avoid unnecessary catheters/restraints

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Step 3 · Pharmacological (if behaviour poses risk to self or others)

1. 1Haloperidol (oral, IM, or IV) - first-line antipsychotic; advantages: multiple formulations, lower risk of sedation and hypotension; use lowest effective dose in elderly
2. 2Risperidone - alternative antipsychotic; not preferred as first-line
3. 3Lorazepam - preferred in alcohol withdrawal delirium, seizure-related delirium, or patients with liver cirrhosis (metabolised by glucuronidation, preserved in cirrhosis); specialist advice for other challenging behaviour

↓

Alcohol withdrawal (normal liver function)

Chlordiazepoxide or diazepam first choice - NOT in liver cirrhosis (CYP450 metabolism impaired, risk of accumulation and toxicity)

Alcohol withdrawal with liver cirrhosis

Lorazepam preferred - glucuronidation preserved even in significant liver impairment

🎯

Haloperidol is first-line pharmacological management for delirium - NOT diazepam or lorazepam (reserved for alcohol withdrawal or specialist use). Avoid benzodiazepines as routine first-line for general delirium - they can paradoxically worsen confusion.

Prevention

•Prescribe laxatives prophylactically when starting constipating medications (opioids, ondansetron)

•Ensure hearing aids and glasses available; adequate hydration and nutrition; maintain mobility; normal sleep-wake cycle

•Review polypharmacy - reduce or stop high-risk medications where possible

Subtypes

Delirium subtypes

Feature	Hyperactive	Hypoactive	Mixed
Behaviour	Agitated, aggressive, hallucinations	Withdrawn, lethargic, slow to respond	Alternates between both
Risk of being missed	Low	High - most commonly missed	Moderate

⚠️

Hypoactive delirium is the most commonly missed subtype - a withdrawn, lethargic patient who is slow to respond is NOT simply tired. Absence of agitation does not equal absence of delirium.

Causes (DELIRIUMS)

DELIRIUMS mnemonic

D - Drugs and alcohol (opioids, anticholinergics, alcohol withdrawal)

E - Eyes, ears, emotional disturbance (sensory deprivation)

L - Low output state (MI, PE, heart failure, COPD)

I - Infection (UTI, pneumonia, sepsis)

R - Retention (urinary retention or constipation)

I - Ictal (post-ictal, non-convulsive status epilepticus)

U - Under-hydration / Under-nutrition

M - Metabolic (electrolytes, thyroid, Wernicke's encephalopathy)

S - Subdural haematoma / Sleep deprivation

💡

Constipation is a commonly missed precipitant - always check the stool chart and look for constipating drugs (opioids, ondansetron) prescribed without laxatives.

Presentation and Diagnosis (CAM)

Delirium is a clinical diagnosis. The Confusion Assessment Method (CAM) requires features 1 AND 2, PLUS either 3 or 4:

1.Acute onset and fluctuating course - change from baseline, waxes and wanes

2.Inattention - difficulty focusing, easily distracted (core feature)

3.Disorganised thinking - rambling, incoherent, illogical

4.Altered level of consciousness - anything other than alert (hyperalert, lethargic, stuporous, comatose)