Delirium Algorithm · Reasoning GP

Safety

Red flags — immediate life threats in acute confusion

Done

Screen FIRST. Acute confusion can mask immediately life-threatening conditions. Any red flag → call 999 or arrange same-day emergency assessment.

Meningism / purpuric rash Neck stiffness, photophobia, petechiae → 999 (bacterial meningitis / meningococcal sepsis)

GCS ≤13 / AVPU ≤V Drowsy, unresponsive → 999 (encephalitis, SDH, stroke, hypoglycaemia)

Hypoglycaemia BM <4 mmol/L → treat immediately (glucose gel/IV dextrose), call 999 if not responding

Sepsis 6 criteria HR >90, RR >20, T <36 or >38.3, confusion → 999 (septic encephalopathy)

Focal neurology / sudden onset New hemiplegia, dysphasia, facial droop → 999 (stroke/TIA, SDH)

Status epilepticus / post-ictal Witnessed seizure, tongue biting, incontinence → 999 if ongoing; assess if post-ictal

Hypertensive crisis BP >180/120 + confusion, headache, papilloedema → same-day emergency (hypertensive encephalopathy)

Drug overdose / toxidrome Opioid miosis/bradypnoea, cholinergic syndrome, serotonin syndrome → 999 + naloxone if opioid

Delirium is a clinical syndrome (not a diagnosis) — the cause must be found. Missing septic encephalopathy carries 20–40% mortality. Hypoglycaemia is reversible but causes permanent brain injury within minutes if untreated. SDH is easily missed especially in elderly on anticoagulants. NICE NG193 mandates same-day assessment for all new acute confusion in older adults.

Diagnose

Confirm delirium — use validated screening tool

Done

Distinguish delirium from dementia, depression or functional psychosis. Use the 4AT (validated for GP/ED use, takes <2 minutes).

4AT Score

0 = No delirium | 1–3 = Possible cognitive impairment | 4+ = Probable delirium. Score 4+ = act as delirium until proven otherwise. Available free at www.the4AT.com

4AT Items

1. Alertness (abnormal=1pt) 2. AMT4 (≤7/10=1pt, ≤6/10=2pt) 3. Attention test (months backwards, errors=1–2pt) 4. Acute change/fluctuation (yes=4pt)

Collateral Hx

ESSENTIAL. Ask carer/family: "What is their normal baseline? When did this start? Has it fluctuated?" A fluctuating course distinguishes delirium from dementia

Timeline

Delirium: acute onset (hours–days), fluctuating. Dementia: gradual over months. Depression: weeks–months, no fluctuation

Delirium subtype

Hyperactive (agitated, restless — 25%) | Hypoactive (drowsy, withdrawn — 50%, most missed) | Mixed (25%)

Hypoactive delirium is missed in up to 70% of cases in hospital settings because patients are quiet and compliant. The 4AT has sensitivity 76–94% and specificity 65–95% (Annals of Emergency Medicine 2019). Collateral history is non-negotiable — patients cannot accurately self-report fluctuation.

Diagnose

Identify the underlying cause — PINCH ME mnemonic

Done

Delirium is always caused by something. Systematically screen for reversible precipitants using PINCH ME (NICE NG193).

P — Pain

Uncontrolled pain (urinary retention, constipation, fracture). Check bladder, bowel, new injury

I — Infection

UTI, chest infection, skin/wound infection, COVID-19. Most common cause in older adults

N — Nutrition

Dehydration, malnutrition, thiamine deficiency (Wernicke's in alcohol dependency)

C — Constipation

Check last bowel movement. Faecal impaction common precipitant

H — Hydration

Dry mucous membranes, reduced urine output, recent vomiting/diarrhoea, poor fluid intake

M — Medication

New drugs or dose changes: opioids, anticholinergics, benzodiazepines, steroids, digoxin, antiepileptics, antihistamines. Check Anticholinergic Burden (ACB) score

E — Environment

Unfamiliar setting, sensory deprivation (missing glasses/hearing aids), sleep disruption, restraint

Medications are precipitants in up to 40% of cases — always review the drug chart with an ACB score calculator. Wernicke's encephalopathy is underdiagnosed and irreversible without IV thiamine — suspect in any alcoholic or malnourished patient. UTI is over-attributed in older adults (asymptomatic bacteriuria is common); look for systemic signs of infection.

Diagnose

Targeted examination

Done

Focused clinical examination to identify reversible causes and assess severity.

Vital signs

Full NEWS2: BP, HR, RR, SpO₂, temperature, BM. Abnormal → guides cause (sepsis, hypoxia, hypo/hyperglycaemia)

Neurological

GCS/AVPU, focal signs, cranial nerves, pupils (unequal → SDH/herniation), neck stiffness (meningitis)

Chest

Crackles/consolidation → pneumonia; wheeze → COPD exacerbation; raised JVP → cardiac cause

Abdomen

Suprapubic tenderness/palpable bladder → urinary retention; distension/tenderness → constipation/obstruction

Skin

Rash (meningococcal, herpes zoster), jaundice (hepatic encephalopathy), pressure sores (sepsis source), turgor (dehydration)

Medication review

Check Rx, OTC, and PRN medications for anticholinergics, opioids, benzodiazepines, polypharmacy (>5 drugs = high risk)

Urinary retention is a common, easily missed cause — always check the bladder in an older confused patient, especially in men with BPH. SpO₂ <92% explains delirium in COPD patients without needing CT head. A proper medication review changes management in >40% of delirium presentations in older adults.

Diagnose

Investigations

Done

Targeted bloods guided by history and examination. Avoid unnecessary investigation but cast a broad net for reversible causes.

First-line Bloods

FBC (infection, anaemia), U&E + Cr (AKI, hypo/hypernatraemia), LFTs, TFTs, CRP/ESR, glucose, calcium, Mg, phosphate

Urine MSU

Dipstick + MC&S. Note: positive dipstick alone in elderly ≠ UTI cause. Nitrites + leukocytes + systemic signs required

Blood cultures

If temperature >38°C or <36°C, or clinical sepsis suspected. Two sets before antibiotics

ECG

AF (new onset), ischaemia, QTc prolongation (if starting antipsychotic), digoxin toxicity

CXR

If respiratory signs, fever without obvious source, or new O₂ requirement

CT head

Same day if: focal neurology, head injury, anticoagulated, GCS <13, no obvious medical cause found. NOT routine

Consider

Thiamine level + blood cultures if alcohol dependency | LFTs + ammonia if liver disease | Troponin if cardiac cause suspected

Hyponatraemia causes delirium at Na <125 mmol/L (and sometimes higher in rapid onset) — commonly missed on clinical exam. Hypercalcaemia from malignancy causes confusion before other symptoms. TFTs pick up myxoedema coma. CT head should not be reflexively ordered — it is negative in >80% of delirium presentations without focal neurology, wastes time and exposes patients to radiation.

Refer

Referral criteria — when to admit

Done

Most delirium should be managed in the least restrictive environment possible. Avoid hospital admission where safe to do so (admission itself worsens delirium).

999 Emergency

GCS ≤13, sepsis criteria met, suspected meningitis/encephalitis, suspected stroke, active seizures, suspected Wernicke's (IV thiamine needed)

Same-day Acute

Delirium with no identifiable/treatable cause in primary care | Unable to manage safely at home | Severe agitation posing risk to self/others | Suspected SDH (anticoagulated patient with fall)

Urgent Geriatrics

Recurrent delirium without clear cause | First delirium episode prompting post-recovery cognitive assessment | New delirium superimposed on known dementia

Home management

Clear reversible cause identified + treated (e.g., UTI, constipation, medication) + adequate carer support + home is safe + daily review possible

Social care

If patient lives alone and lacks capacity → safeguarding referral + contact next of kin/DoLS if admission necessary

Hospital admission increases delirium duration by exposing patients to noise, disrupted sleep, immobility and unfamiliar environments. NICE NG193 recommends home management when clinically safe. However, 30-day mortality for delirium in older adults is 14% — do not under-triage. Patients admitted to hospital with delirium have a 5-fold increased risk of subsequent dementia.

Treat

Management — treat the cause first; non-pharmacological priority

Done

Treat the underlying cause. Non-pharmacological approaches are first-line for all delirium. Sedation is a last resort.

Treat cause

Non-pharm First-line

Sleep hygiene

Protect night-time sleep: avoid unnecessary obs, reduce noise, avoid bright lights. Avoid night sedation if possible

Step 1Non-pharmacological only — for all patients. Address PINCH ME causes. Reassure and reorient repeatedly

Step 2Pharmacological only if: patient at risk of harm to self/others AND non-pharmacological measures have failed. NOT for distress alone

Drug option AHaloperidol 0.5 mg oral/IM (elderly: start 0.25 mg). Max 1–2 mg/24h. Caution QTc prolongation, Parkinson's disease (avoid), Lewy body dementia (absolutely contraindicated — can cause fatal NMS)

Drug option BLorazepam 0.5–1 mg oral/IM — preferred in alcohol withdrawal, Parkinson's, Lewy body. Risk of paradoxical agitation and respiratory depression in elderly

AvoidBenzodiazepines as routine first-line (worsens delirium duration) | Promethazine | High-dose antipsychotics | Physical restraint (worsens agitation and causes injury)

NICE NG193 (2023): pharmacological sedation does not shorten delirium duration and is associated with increased mortality. Haloperidol NNT for symptom control ≈6 but increases mortality risk if used routinely. Lewy body dementia affects 10–15% of dementia patients — antipsychotics cause severe neuroleptic sensitivity in 50–60%, with 2–3x mortality risk. Always check dementia subtype before prescribing.

Lifestyle

Prevention — reducing future delirium risk

Done

Delirium is preventable in 30–40% of cases. Proactive prevention in at-risk patients (elderly, dementia, frailty, polypharmacy) reduces incidence and mortality.

Medication review Annual ACB scoring. Deprescribe anticholinergics, benzodiazepines, opioids where possible. Target polypharmacy (>5 drugs = high risk)

Sensory aids Ensure glasses and hearing aids are prescribed, functional and always accessible. Sensory deprivation doubles delirium risk

Hydration Target 6–8 glasses fluid/day. Encourage oral fluids proactively in hot weather or during illness

Sleep hygiene Regular sleep-wake cycle. Avoid sedating medications at night. Treat sleep disorders (OSA, insomnia) without benzodiazepines

Constipation prevention Regular aperients if opioids prescribed. High-fibre diet. Adequate mobility. Laxative review at every medication review

Cognitive stimulation Social engagement, cognitive activity (crosswords, conversation). Reduces incident dementia and delirium vulnerability

Advance care planning Document baseline cognitive function in notes. Agree delirium management plan with carer/family — reduces inappropriate hospital admissions

Carer education Provide NICE delirium information leaflet. Teach PINCH ME to carers of high-risk patients

The HELP (Hospital Elder Life Program) showed non-pharmacological prevention reduced delirium incidence by 34% (NEJM 1999). Anticholinergic burden is a modifiable risk factor — ACB score >3 doubles delirium risk and is associated with 26% increased dementia incidence (BMJ 2019). Every episode of delirium accelerates cognitive decline.

Safety

Follow-up, monitoring & safety-netting

Done

Delirium can take days–weeks to resolve. Post-delirium cognitive assessment is mandatory. Safety-net carers clearly.

24–48h

Daily review if managed at home. Check: delirium resolving? Cause identified and treated? Carer coping? Medications reviewed?

1 week

Review investigation results. Reassess cognition (4AT). If no improvement → consider admission or specialist referral

4–6 weeks

Post-delirium cognitive assessment (MMSE or MoCA when fully recovered). 30–40% of patients have underlying dementia unmasked by delirium — refer to memory clinic if cognitive deficit persists

3 months

Medication review — deprescribe contributing drugs. Falls risk assessment. Formal frailty assessment (eFI or Rockwood CFS)

999 safety-net

Sudden deterioration in consciousness, new seizure, focal neurology, petechial rash, respiratory arrest — call 999 immediately

Same-day GP

Delirium not improving after 48–72h | New fever developing | Increasing agitation despite treatment | Carer no longer able to cope | Suspected medication side effect

Documentation

Record: delirium episode, cause, treatment, cognition at recovery. Flag as high-risk in notes for future hospital/care admissions

Persistent delirium beyond 7 days significantly worsens prognosis — 1-year mortality doubles compared to delirium resolving in <48h (Lancet 2014). Post-delirium dementia screening detects otherwise missed dementia in ~35% of cases. NICE NG193 mandates written information for carers about delirium recognition and what to do. Recurrent delirium without clear cause warrants specialist geriatric assessment.