Delirium: Recognition, Assessment, Causes and Emergency Management

Delirium is an acute neuropsychiatric syndrome characterised by a disturbance in attention and awareness that develops over a short period, fluctuates during the day and is caused by an underlying medical, toxicological or medication-related problem. It is common, dangerous and frequently missed, especially when the patient is quiet or sleepy. Delirium is not simply “confusion,” dementia, psychosis or bad behaviour.

Learning objectives

• Define delirium and recognise hyperactive, hypoactive and mixed presentations.
• Use bedside attention and arousal assessment and a structured tool such as the 4AT or CAM.
• Identify common precipitants and red flags for infection, neurological disease, toxicology and metabolic emergencies.
• Plan immediate investigations, non-drug management, medication review and prevention.
• Communicate with family, document fluctuation and arrange follow-up after recovery.

1. Core diagnostic features

2. Types of delirium

• Hyperactive: agitation, restlessness, shouting, aggression, hallucinations, pulling lines or attempting to leave.
• Hypoactive: drowsiness, slowed responses, reduced movement, withdrawal, quiet confusion and poor intake. It is easily mistaken for depression or fatigue.
• Mixed: alternates between agitation and reduced arousal.

Type does not determine severity. Hypoactive delirium may carry a high risk because deterioration is less visible and the cause can be missed.

3. Who is at risk?

• Older age, dementia, previous delirium, frailty or severe cognitive impairment.
• Severe infection, surgery, trauma, burns, pain, dehydration, hypoxia or immobility.
• Renal/hepatic failure, electrolyte or glucose disturbance, anaemia and malnutrition.
• Polypharmacy, anticholinergic medicines, sedatives, opioids, corticosteroids and abrupt withdrawal.
• Alcohol or benzodiazepine withdrawal, stimulant or other drug intoxication.
• Visual/hearing impairment, unfamiliar environment, sleep disruption, urinary retention and constipation.
• Critical illness, mechanical ventilation, neurological disease and severe systemic inflammation.

4. Delirium versus other presentations

5. Immediate assessment: ABCDE plus attention

1. Airway and breathing: patency, respiratory rate, oxygen saturation, aspiration risk, carbon dioxide retention and respiratory depression.
2. Circulation: pulse, blood pressure, perfusion, temperature, ECG, sepsis screen and intravenous access when needed.
3. Disability: capillary glucose, AVPU/GCS, pupils, seizure activity, focal deficits, pain and signs of intoxication or withdrawal.
4. Exposure: fever, rash, trauma, pressure injury, dehydration, urinary retention, constipation, medication patches and evidence of poisoning.
5. Attention: ask the person to follow a simple conversation, recite months backwards, digit span or sustain eye contact; compare with baseline.
6. Collateral: ask family or caregivers exactly when the change began, what is different and what the person’s baseline function was.

6. Structured tools

6.1 The 4AT

The 4AT is a rapid delirium screen with four domains:

1. Alertness: normal, clearly abnormal hyperalert or drowsy.
2. AMT4: age, date of birth, place and current year.
3. Attention: months of the year backwards or another validated attention task.
4. Acute change or fluctuating course: from informant, notes or observation.

A positive score supports further clinical assessment; it does not identify the cause or replace examination. Consider sensory impairment, language, education, aphasia and baseline cognition.

6.2 Confusion Assessment Method (CAM)

CAM requires acute onset and fluctuating course plus inattention, and either disorganised thinking or altered level of consciousness. Use only with training and clinical judgement. Record the actual findings rather than writing “CAM positive” alone.

7. Investigating the cause

7.1 Bedside and immediate tests

• Capillary glucose, oxygen saturation, temperature, pulse, blood pressure and respiratory rate.
• ECG for arrhythmia, overdose, electrolyte disturbance or QT-risk medicines.
• Bladder scan where urinary retention is possible; assess bowel function and pain.
• Pregnancy test where relevant before radiation or teratogenic treatment.

7.2 Laboratory and infection assessment

• Full blood count, electrolytes, urea/creatinine, calcium/magnesium, glucose, liver function and urinalysis.
• Blood cultures, urine culture, malaria testing, HIV/TB or other infection tests according to symptoms, immune status and local epidemiology.
• Blood gas, lactate, ketones, toxicology or drug levels when respiratory failure, shock, diabetic ketoacidosis, poisoning or medicine toxicity is possible.
• Medication reconciliation including anticholinergics, opioids, sedatives, steroids, antihistamines, withdrawal of alcohol/benzodiazepines and recently changed medicines.

7.3 Neurodiagnostics

• Urgent CT for head injury, focal deficit, severe sudden headache, anticoagulation, seizure or concern about bleeding/mass effect.
• MRI for subacute unexplained cognitive change, atypical presentations or suspected encephalitis/structural disease when stable and available.
• EEG for suspected non-convulsive status, unusual spells, post-ictal confusion or persistent unexplained fluctuating consciousness.
• Lumbar puncture for suspected meningitis/encephalitis after contraindication assessment and urgent senior advice; never delay emergency antibiotics when meningitis is suspected.

8. Treating delirium: find and correct the cause

• Infection: cultures and prompt antimicrobial treatment according to local protocol when indicated.
• Hypoxia or respiratory failure: oxygen and ventilatory support; investigate pneumonia, pulmonary disease or opioid/sedative effect.
• Metabolic disturbance: correct glucose, electrolytes, renal/hepatic failure, dehydration and acid-base disorders safely.
• Medication or toxin: stop non-essential contributors; use an antidote only with appropriate toxicology guidance.
• Withdrawal: use a validated local alcohol/benzodiazepine withdrawal pathway; monitor seizures and autonomic instability.
• Pain, urinary retention and constipation: assess actively and treat while avoiding excessive sedation or anticholinergic burden.
• Neurological disease: urgent stroke, seizure, infection, trauma or neurosurgical pathways as indicated.

9. Non-pharmacological management

• Provide a calm, well-lit, familiar environment with a visible clock and calendar.
• Use the patient’s glasses, hearing aids, dentures and preferred language.
• Reorient gently; explain who staff are and what is happening without arguing about perceptions.
• Invite a trusted family member or caregiver when this is safe and calming.
• Promote sleep at night: reduce noise/light, cluster care and avoid unnecessary overnight observations while maintaining safety.
• Encourage hydration, nutrition, mobilisation and physiotherapy; prevent pressure injuries and falls.
• Remove unnecessary lines, catheters and restraints. Restraint can worsen fear, injury and delirium and is a last resort under policy.

10. Medicines for severe distress or danger

Medication is not a cure for delirium. Use it only when non-drug measures fail and the patient has severe distress, psychosis or immediate danger to self/others, or essential treatment cannot be delivered. Seek senior advice, use the lowest effective dose for the shortest period and monitor sedation, airway, blood pressure, ECG and extrapyramidal effects.

• Review Parkinson disease, Lewy-body dementia, QT prolongation, seizure risk, respiratory depression, hepatic/renal impairment and drug interactions before using an antipsychotic.
• Avoid routine benzodiazepines because they can worsen delirium, except in alcohol/benzodiazepine withdrawal, catatonia or specific seizure-related indications.
• Do not use antipsychotics to manage ordinary wandering, sleep disturbance or staff convenience.
• Reassess daily and stop as soon as the indication ends.

11. Prevention bundle

12. Complications and follow-up

• Falls, aspiration, pressure injury, dehydration, malnutrition, functional decline and prolonged admission.
• Self-harm, aggression, accidental removal of lines or wandering.
• Persistent cognitive impairment, PTSD-like distress and increased risk of later dementia or relapse of underlying disease.
• After recovery, reassess cognition, medication burden, function, mood, sleep, driving, capacity and caregiver needs. Explain that recovery can take days to weeks.

13. Documentation

14. Worked cases

Case 1: Hyperactive delirium from sepsis

A patient with fever, tachycardia and pneumonia is shouting that staff are attacking them and trying to leave. The acute fluctuating course and inattention suggest delirium. Stabilise, treat infection and hypoxia, provide a calm environment, involve family and use medication only if severe danger persists.

Case 2: Hypoactive delirium after surgery

A patient is unusually sleepy, answers slowly and eats very little. This is not “just postoperative fatigue.” Check oxygen, glucose, infection, pain, urinary retention, constipation, medicines, electrolytes and baseline cognition. Repeat assessment because hypoactive delirium can be missed.

Case 3: Alcohol withdrawal

A dependent drinker develops tremor, sweating, tachycardia, insomnia and visual hallucinations two days after admission. Assess for severe withdrawal, seizures and delirium tremens, use the local medically supervised withdrawal protocol and monitor closely. Do not use an isolated antipsychotic as the primary treatment for withdrawal physiology.

15. Quick self-test

1. What are the two core cognitive features of delirium?
2. Why is hypoactive delirium dangerous?
3. What does the 4AT assess?
4. Name six reversible precipitants.
5. When should benzodiazepines be considered in delirium?
6. What non-drug measures reduce delirium?
7. Why should antipsychotics not be used for staff convenience?
8. What follow-up is needed after apparent recovery?

Answers

1. Disturbance in attention and awareness, with an acute and fluctuating course.
2. It appears quiet or sleepy, so staff may miss severe infection, hypoxia, metabolic illness or medication toxicity.
3. Alertness, a brief orientation screen, attention and acute/fluctuating change.
4. Infection, hypoxia, glucose/electrolyte disturbance, dehydration, pain, urinary retention, constipation, medication effect, intoxication/withdrawal, seizure and head injury.
5. Alcohol or benzodiazepine withdrawal, catatonia or a specific seizure-related indication under medical supervision; they may worsen other delirium.
6. Orientation, sensory aids, sleep protection, hydration/nutrition, mobilisation, pain/retention/constipation treatment, familiar people and reducing restraints/lines.
7. They can cause sedation, aspiration, falls, QT effects and extrapyramidal symptoms without treating the underlying cause.
8. Cognition, function, mood, medicines, sleep, driving/capacity, caregiver support and the underlying medical cause.

References and further reading

• NICE. Delirium: prevention, diagnosis and management.
• WHO. mhGAP Intervention Guide, version 2.0.
• WHO. mhGAP guideline for mental, neurological and substance use disorders, 2023.
• Use Uganda Ministry of Health protocols for sepsis, malaria, HIV/TB, poisoning, alcohol withdrawal, safeguarding and referral.