Delirium: Recognition, Assessment, Causes and Emergency Management
Clinical Medicine Year 2 • Mental Health Disorders • Emergency Focus 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. Emergency principle: Delirium is a medical emergency until the precipitating cause is found and treated. Stabilise airway, breathing and circulation; check glucose and oxygenation; assess sepsis, stroke, seizure, overdose, withdrawal, hypoxia, electrolyte disturbance, head injury and medication toxicity. 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 Feature What to look for Acute onset New change over hours to days, or clear worsening from a recent baseline Fluctuating course Better and worse periods, often worse at night; document when the patient is most alert Inattention Cannot sustain or shift focus; easily distracted; loses the thread of conversation Altered awareness Hyperalert, lethargic, stuporous or variably responsive Cognitive/perceptual change Disorientation, memory impairment, disorganised thinking, illusions or hallucinations Medical cause Evidence of infection, metabolic illness, medication, intoxication/withdrawal, neurological or other physiological disturbance 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 Condition Distinguishing features Delirium Acute/fluctuating course, impaired attention and altered arousal; medical cause likely Dementia Insidious progressive decline; attention relatively preserved early; delirium may be superimposed Depression Low mood, reduced motivation and slowed thinking but attention usually more consistent; can coexist with delirium Psychosis Delusions/hallucinations with relatively clear attention and arousal in primary psychosis; visual hallucinations and fluctuation suggest delirium Catatonia Marked psychomotor syndrome; may coexist with delirium or be caused by medical illness; rigidity, mutism and posturing need specialist assessment Non-convulsive seizure Episodes of altered awareness or automatisms; EEG may be required 5. Immediate assessment: ABCDE plus attention Airway and breathing: patency, respiratory rate, oxygen saturation, aspiration risk, carbon dioxide retention and respiratory depression. Circulation: pulse, blood pressure, perfusion, temperature, ECG, sepsis screen and intravenous access when needed. Disability: capillary glucose, AVPU/GCS, pupils, seizure activity, focal deficits, pain and signs of intoxication or withdrawal. Exposure: fever, rash, trauma, pressure injury, dehydration, urinary retention, constipation, medication patches and evidence of poisoning. Attention: ask the person to follow a simple conversation, recite months backwards, digit span or sustain eye contact; compare with baseline. 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: Alertness: normal, clearly abnormal hyperalert or drowsy. AMT4: age, date of birth, place and current year. Attention: months of the year backwards or another validated attention task. 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

