Delirium (sometimes called 'acute confusional state') is an acute, fluctuating syndrome of disturbed consciousness, attention, cognition and perception.  Delirium usually develops over hours to days and behavioural disturbance, personality changes, and psychotic features may occur.  It typically occurs in people with predisposing factors (such as advanced age or multiple comorbidities) when new precipitating factors (such as some medications or infection) are added.  Delirium can be hypoactive or hyperactive but some people show signs of both (mixed). People with hyperactive delirium have heightened arousal and can be restless, agitated and aggressive. People with hypoactive delirium become withdrawn, quiet and sleepy. Hypoactive and mixed delirium can be more difficult to recognise.  The prevalence of delirium among people aged 65 years and over living in long-term care is 10–40%, whilst delirium is thought to affect up to 50% of older people (over 65 years) in hospital


Clinical features

Behaviour change develops acutely (over hours to days).  Usually there is clinical evidence of an underlying precipitating factor such as infection or an adverse drug reaction.  Symptoms typically fluctuate (come and go or increase and decrease in severity). Lucid intervals usually occur during the day with the worst disturbance at night


Behavioural changes may include:

  1. Altered cognitive function — the person may be disoriented, have memory and language impairment, worsened concentration, slow responses, and confusion. The person may not be able to recall details of their current illness, instructions, or names
  2. Inattention — the person may be easily distractIble and have difficulty focusing and moving attention from one thing to another, for example they are unable to maintain a conversation or follow reasonable commands
  3. Disorganised thinking — the person may have disorganised, rambling, or irrelevant conversation, unclear or illogical flow of ideas, and difficulty expressing their needs and concerns
  4. Altered perception — the person may experience paranoid delusions, misperceptions or, visual or auditory hallucinations (in about 30% of people) which may be distressing
  5. Altered physical function:
    1. Hyperactive delirium — the person may have increased sensitivity to their immediate surroundings with agitation, restlessness, sleep disturbance, and hyper-vigilance. Restlessness and wandering are common
    2. Hypoactive delirium (more common) — the person may be lethargic, have reduced mobility and movement, lack interest in daily activities, have a reduced appetite, and become quiet and withdrawn
    3. Mixed — the person will have a combination of signs and symptoms of hyperactive and hypoactive subtypes
  6. Altered social behaviour — the person may have intermittent and labile changes in mood and/or emotions (such as fear, paranoia, anxiety, depression, irritability, apathy, anger, or euphoria). Their behaviour may be inappropriate and they may not co-operate with reasonable requests or become withdrawn
  7. Altered level of consciousness — the person may have a clouding of consciousness, reduced awareness of their surroundings, and sleep-cycle disturbances (such as daytime drowsiness, night-time insomnia, disturbed sleep, or complete sleep cycle reversal). Impaired consciousness can be subtle, and may initially only be apparent as lethargy or distractibility


NOTE:  Falling and loss of appetite are often warning signs for delirium



NOTE:  Delirium is a clinical diagnosis based on a detailed history, examination, and relevant investigations

Take a history from the person and an informed observer (family member or carer) asking about:

  1. The onset, nature, and course of the behaviour change — acute behaviour change (developing over hours or days) which fluctuates is suggestive of delirium
  2. Baseline functional and cognitive state.  (If possible carry out a cognitive screening test)
  3. Precipitating factors such as:
    1. New illnesses (for example infection, urinary retention, or constipation)
    2. Recent discharge from hospital
    3. Falls
    4. Acute or chronic pain
    5. Poor oral intake (fluid and nutrition)
    6. Recent changes in environment
    7. Comorbidities (for example chronic obstructive pulmonary disease, depression, terminal illness, catheterization, or dementia)
    8. Current medication (including over-the-counter medications and herbal remedies), possible deliberate or accidental drug overdose and recent drug cessation (especially benzodiazepines)
    9. Alcohol use
    10. Sensory impairment (for example reduced vision and hearing, use of hearing aids or glasses)


Examine the person:

  1. Check vital signs including temperature, blood pressure, heart rate, capillary refill time, finger-prick blood glucose, and pulse oximetry — to identify fever, hypoperfusion, hyperglycaemia, hypoglycaemia, or hypoxia
  2. Carry out a general examination to identify precipitating factors such as:
    1. Respiratory conditions, for example chest infection, pulmonary embolus, heart failure, or chronic obstructive pulmonary disease
    2. Cardiovascular conditions, for example myocardial infarction and heart failure
    3. Abdominal conditions, for example acute abdomen, constipation, faecal loading (carry out a rectal exam if possible if impaction is suspected), urinary retention, and urinary tract infection
    4. Musculoskeletal conditions, for example hip fracture
    5. Neurological conditions, for example stroke, subdural haematoma, epilepsy, encephalitis, or drug intoxication
    6. Skin conditions, for example infection, pressure sores, or ulcers
    7. Electrolyte imbalance such as dehydration, acute kidney injury, hypercalcaemia, or hyponatraemia
    8. Endocrine and metabolic disorders such as cachexia, thiamine deficiency, or thyroid dysfunction
    9. Sensory impairment, for example impacted ear wax, ill-fitting or non-functioning hearing aids, and spectacles
    10. Pain — look for non-verbal signs of pain, particularly in people with communication difficulties



Confirm a diagnosis of delirium by carrying out a cognitive assessment based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria or the short Confusion Assessment Method (short-CAM)

  1. To make a diagnosis of delirium using the DSM-IC criteria, all four criteria must be present
  2. to make a diagnosis of delirium using the short-CAM criteria, criterion 1 and 2 must be present, plus either criterion 3 or 4



NOTE:  Most people with delirium will need admission for same-day investigation and treatment of precipitating factors

If admission is not appropriate, arrange targeted investigations based on findings from the history and examination, for example:

  1. Urinalysis — to identify conditions such as infection or hyperglycaemia. Arrange a mid-stream urine (MSU) if urinalysis is abnormal
  2. Sputum culture — to identify chest infection
  3. FBC — to identify infection or anaemia
  4. Folate and B12 — to identify vitamin deficiency
  5. Urea and electrolytes — to identify acute kidney injury and electrolyte disturbance (such as hyponatraemia or hypokalaemia)
  6. HbA1c — to identify hyperglycaemia
  7. Calcium — to identify hypercalcaemia or hypocalcaemia
  8. LFTs — to identify hepatic failure and rule out hepatic encephalopathy
  9. ESR and CRP — can help to identify infection or inflammation
  10. Drug levels — to identify drug toxicity, for example if the person has taken digoxin, lithium, or alcohol
  11. TFT — to identify hyperthyroidism or hypothyroidism
  12. Chest X-ray — to identify conditions such as pneumonia and heart failure
  13. ECG — to identify cardiac conditions including arrhythmias


Admission and referral

Most people with delirium should be admitted to hospital for urgent assessment, close monitoring, and treatment. If the person with delirium refuses admission, ask carers or family (if appropriate) to help persuade the person. If this fails, consider admission under the Mental Capacity Act (2005)

Management in primary care may be appropriate if all of the following are present: 

  1. The benefits of management in primary care outweigh the benefits of hospital admission, or the person is clinically well enough to stay at home
  2. The symptoms of delirium are not harmful to the person or others, and can be managed safely in primary care
  3. The cause of delirium is known and treatable
  4. The person can receive constant supervision and care from a healthcare professional trained in the management of delirium — to minimize complications
  5. Close clinical follow-up can be arranged


Management in primary care

If appropriate to manage in primary care:

  1. Correct any precipitating factors (e.g. infection, medications, constipation, urinary retention, dehydration and electrolyte imbalance, pain, sensory impairment)
  2. Optimize treatment of comorbidities (e.g. COPD, dementia, diabetes, heart failure, thyroid disease, Parkinson's disease, CVD)
  3. Advise family and carers that they should provide simple explanations for all activities in a calm manner, try reorientation strategies, maintain safe mobility, and normalize the sleep-wake cycle
  4. If the person with delirium develops challenging behaviour (such as aggression, agitation, or shouting), address any underlying causes for the behaviour (e.g. discomfort), advise moving the person to a safe, low-stimulation environment (such as a quiet room), and advise use of verbal and non-verbal de-escalation techniques (such as active listening, effective verbal responding, pictures, and symbols)
  5. Explain the diagnosis of delirium to the person and their carers and provide written information
  6. Arrange follow up by reviewing the person within 24 hours of initial assessment and regularly thereafter until symptoms have resolved; adjust the management plan if appropriate.  Arrange admission or seek advice from an elderly care physician or psychiatrist, if the person fails to improve or they deteriorate


Delirium in End of Life Care

Managing delirium in end of life care:

  1. Explore the possible causes of delirium with the dying person and those important to them. Be aware that agitation in isolation is sometimes associated with other unrelieved symptoms or bodily needs for example, unrelieved pain or a full bladder or rectum
  2. Consider non-pharmacological management of delirium in a person in the last days of life
  3. Treat any reversible causes of delirium, for example, psychological causes or certain metabolic disorders (for example renal failure or hyponatraemia)
  4. Ensure that suitable anticipatory medicines are prescribed as early as possible. Review these medicines as the dying person's needs change
  5. Consider a trial of an antipsychotic medicine (such as haloperidol or levomepromazine) to manage delirium
  6. Monitor the benefits and side effects of these medicines at least daily and adjust the prescription as the clinical situation changes
  7. Seek specialist advice if the diagnosis of delirium is uncertain, if the delirium does not respond to antipsychotic treatment or if treatment causes unwanted sedation


Confirm a diagnosis of delirium by carrying out a cognitive assessment based on the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria or the short Confusion Assessment Method (short-CAM)

  • To make a diagnosis of delirium using the DSM-IC criteria, all four criteria must be present
  • to make a diagnosis of delirium using the short-CAM criteria, criterion 1 and 2 must be present, plus either criterion 3 or 4

Advice and Guidance is being made available for all specialties, and is being provided by consultant specialists at East Kent Hospitals.  To make a request or to check to if a query has been answered, you will need to log in via the electronic Referral System (eRS)

Click here for the "how to access" e-Referral Advice and Guidance Manual for instructions on how to make a request and check responses

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