Author: Steve Fordham / Editor: Clifford J Mann / Reviewer: Liz Florey, Mohamed Elwakil, Sandi Angus / Codes: ELC2, ELC8, ELP1, SLO1, SLO7Published: 14/08/2023


Delirium is among the most common of medical emergencies. Prevalence is around 20% in adult acute general medical patients, and higher in particular clinical groups, such as patients in intensive care units. It affects up to 50% of those who have hip fracture and up to 75% in intensive care [1].

Patients with delirium have:

  • Increased length of hospital stay
  • Higher risk of complications in both medical and surgical settings
  • Higher mortality, both in hospital and up to 6 months following discharge [2]
  • High risk of developing dementia in future [3]

Preventative measures can reduce the incidence of delirium [1]. It is an essential skill for emergency physicians to be able to identify, rationally assess and implement effective initial treatment strategies in confused elderly patients.


The diagnosis of delirium is clinical. The DSM-V criteria for defining delirium are [3,4]:

  • Disturbance of consciousness i.e. reduced clarity of awareness of the environment, with reduced ability to focus, sustain or shift attention
  • A change in cognition such as memory deficit, disorientation, language disturbance or the development of a perceptual disturbance.
  • The presence of a ‘general medical condition’ – In practice this is usually assumed rather than specified in each case.

NICE guideline [2] describes delirium, also known as ‘acute confusional state’, as disturbed consciousness, cognitive function or perception with an acute onset and fluctuating course. It develops over a short period of time, usually over a couple of days, and may lead to poor outcomes [2].

Three clinical subtypes of delirium are recognised: Hypoactive, Hyperactive and Mixed [2].

Subtype Feature
  • Heightened arousal
  • Restless
  • Agitated and sometimes aggressive
  • Decreased alertness
  • withdrawn
  • Quiet and sleepy

Key features of delirium [1]:

  • Recent onset of fluctuating awareness
  • Impairment of memory and attention
  • Disorganised thinking

Risk Stratification

In hospitalised patients, there are a number of risk factors for:

Developing delirium

Risk Factors for Developing delirium [2]:

  • Age >65
  • Cognitive impairment past/present
  • Dementia
  • Current hip fracture
  • Severe illness, likely to deteriorate

Precipitating delirium

Precipitating Factors for delirium [2]:

  • Disorientation
  • Dehydration
  • Constipation
  • Hypoxia
  • Infection
  • Immobility/reduced mobility
  • Pain
  • Polypharmacy
  • Poor nutrition
  • Sensory impairment (e.g. hearing or visual impairment)
  • Poor sleep

High-risk patients should be identified in the ED and appropriate prevention strategies implemented.


The ADEPT tool was developed to help Emergency Medicine professionals provide adequate and thorough care for older adults suffering from agitation or delirium. ADEPT stands for the following core principles: assess, diagnose, evaluate, prevent, and treat [6].

Fig. 1 ADEPT tool [6]


A detailed history is often difficult to obtain in delirious patients. Effort should always be made to obtain information from:

  • Carers
  • General practitioners
  • Others close to the patient

In addition to standard questions, useful points to remember, and document, are:

  • Onset and course of delirium
  • Previous intellectual function, e.g. ability to manage household affairs, pay bills, compliance with medication, use of telephone and transport
  • Full drug history, including non-prescribed drugs and recent drug cessation
  • Alcohol history
  • Functional status – activities of daily living (ADL)
  • Aids used (hearing/glasses etc.)

Learning Bite

Many patients with delirium are unable to provide an accurate history. Wherever possible, corroboration should be sought from the carer, general practitioner or any source with good knowledge of them.


A full examination should be performed to search for evidence of underlying causes of the confusion and a 4AT [7] should be completed.

Distinguishing between delirium, dementia and primary psychiatric illness can be challenging as neuropsychiatric symptoms such as psychosis and depression often co-exist in patients with dementia. NICE recommends that if there is difficulty distinguishing between them, to manage the delirium first.

The following table may help with the differentiation between them.

Table 1 Distinguishing features between delirium, dementia, and psychosis [6]

Characteristic Delirium Dementia Psychosis
Onset Acute Gradual Variable
Course Fluctuating Progressive* Chronic
Diminished level of consciousness May be present (hypoactive/mixed delirium) Absent Absent
Orientation Fluctuating Impaired Normal
Duration Hours to months Months to years Months to years
Hallucinations Common Rare until end stage Common
Attention Impaired Preserved until end stage May be Impaired
Sleep-wake pattern Disrupted Normal or fragmented Variable

*Exception: fluctuations in cognition are present in Lewy body dementia.

Investigations should be directed towards potential risk factors for, or causes of, the delirium found from the history and examination.

Routine investigations

The following should be routine in any confused patient:

At the bedside:

  • Oxygen saturation
  • Blood glucose (finger prick)
  • Electrocardiogram
  • Urine dipstick +/- MSU
  • Chest x-ray

In the laboratory:

  • Full blood count
  • U&E
  • Glucose

Specific laboratory tests

Other specific laboratory tests to consider, depending on initial assessment findings, are:

  • Arterial blood gases +/-carboxyhaemoglobin
  • LFT
  • Coag
  • TFT
  • Blood cultures
  • Drug levels (e.g. theophylline, digoxin)
  • B12, folate, VDRL, autoimmune screen
  • D-Dimer (only as part of focussed DVT/pulmonary embolism work up)

Computerised Tomography (CT) scanning

There is no evidence for the use of routine CT head scanning in the initial investigation of acute delirium. Indications for CT in the investigation of acute delirium are:

  • Focal neurologial signs
  • Confusion after a head injury or fall
  • Evidence of raised intracranial pressure

Lumbar puncture (LP)

LP should be reserved for patients in whom meningitis, or another central nervous system (CNS) infective cause, is suspected.

There is no evidence for its routine use.

The most important task in the management of delirium is the identification and treatment of the underlying cause.


Infection is one of the most common causes of delirium. If infection is suspected, it is essential to commence prompt antibiotic treatment directed at likely organisms, following the collection of appropriate cultures.

However, it is important to remember that it is not the only cause and not present in all cases. UTIs, in particular, are often over-diagnosed [8].

Drug History

Drug history should be reviewed and medications withdrawn, as necessary.

Anticholinergic drugs are particularly implicated in precipitating acute confusional states. Polypharmacy has a role to play in delirium, so consider the indications, potential side-effects and the potential anticholinergic burden [8]. (see next page)

Typical offending medications include [8]:

  • Tricyclic antidepressants e.g. amitryptilline
  • Antimuscarinics e.g. oxybutynin
  • Antihistamines e.g. cetirizine, loratadine, hydroxyzine
  • H2 receptor antagonists e.g. ranitidine
  • Opioids e.g. codeine
  • Benzodiazepines e.g. lorazepam
  • Gabapentin
  • Theophylline
  • Hyoscine


If alcohol abuse, or withdrawal is suspected, remember parenteral thiamine

Biochemical Abnormalities

Biochemical abnormalities (e.g. sodium) do not always occur acutely, and normalisation should proceed cautiously.

The approach to this is multifactorial and includes [9]:

  • Identifying and managing each underlying cause or combination of causes
  • Effective regular communication with the patient
  • Regularly reorientating the patient. Consider involving friends, family and carers to help with this.
  • Nursing in a suitable care environment
  • Educating caregivers, using written information such as the following leaflet from BGS/RCPsych [9].

Anticholinergic Drugs

Drugs with anticholinergic activity are commonly used in older people [10]. Examples are shown in the table below.

Table 1 Anticholinergic drugs

Type of drug Example
Antihistamine Hydroxyzine, diphenhydramine
Antispasmodic Alverine, hyoscyamine
Tricyclic antidepressant Amitriptyline
Benzodiazepine Lorazepam
Analgesic Codeine
Antiarrhythmic Digoxin
Diuretic Furosemide
Antiparkinsonian Orphenadrine, benzatropine (US vs. UK)
Bladder stabiliser Oxybutynin
Bronchodilator Theophylline

When several of these are co-prescribed, the anti-cholinergic burden (ACB) is increased and leads to greatly increased risk of adverse effects in the elderly [11].

Preventative and Nursing Measures

Some strategies that are simple to implement in the ED include:

  • Appropriate lighting levels for time of day
  • Regular and repeated cues to improve personal orientation
  • Use of clocks to improve orientation
  • Hearing aids and spectacles in good working order
  • Communication with relatives as to the cause and treatment measures for delirium
  • Encourage family to visit (may help calm patient) and to bring in familiar objects from home

What medical treatment considerations would be considered to minimise confusion?

  • Regular analgesia if in pain
  • Optimise fluid balance to prevent dehydration
  • Elimination of unexpected and irritating noise or other unfamiliar distractions (e.g. pump alarms)
  • Give fluids/medications orally, if possible


  • Use of physical restraint
  • Constipation
  • Catheters, where possible
  • Anticholinergic drugs
  • Unnecessary inter/intra ward transfers

Drug Therapy

Drug therapy in the management of delirium should be avoided, if possible. Sedation may be required in the following situations [2]:

  • To carry out essential investigations or treatment
  • To prevent the patients endangering themselves or others
  • To relieve distress in a highly agitated or hallucinating patient

If drug treatment is necessary

If drug treatment is necessary, haloperidol is the current initial medication of choice. An appropriate starting dose would be 0.5-1 mg, administered orally or IM, with regular reassessment and titration up to a maximum of 5mg. It is best to avoid haloperidol in reduced GCS or clinical significant cardiac conditions.

There is no evidence to support the use of newer antipsychotic medications (e.g. olanzapine, risperidone) in the management of delirium [12].

Side effects

Side effects include extrapyramidal symptoms, which patients experience from dopamine-receptor blocking agents such as the first-generation antipsychotics haloperidol and phenothiazine neuroleptics [13]. For this reason, haloperidol should be avoided in patients with Parkinson’s or Lewy body dementia.

The symptoms of extrapyramidal side effects are debilitating and affect mobility, communication and day-to-day activities [13].

Regular electrocardiography (ECG) monitoring should be performed to ensure that the QT interval does not become prolonged.

For delirium due to alcohol withdrawal, or those not suitable for haloperidol, a benzodiazepine would be suitable. Lorazepam, at an initial dose of 2 mg (IM/IV), with regular reassessment and titration to effect, is preferred.

Safety Pearls and Pitfalls

  • Failure to consider the diagnosis, particularly the hypoactive subtype
  • Failure to routinely assess the mental state of all elderly in the emergency department
  • Failure to obtain a corroborate history from relatives, carers or friends. This is particularly important when trying to distinguish between delirium and dementia
  • Failure to obtain a full drug history
  • Failure to appreciate that injury (particularly head injury) and pain are important causes of acute confusion
  • Requesting insufficient or inappropriate investigations. A full set of all blood tests/x-rays/CT scans is not needed in the initial management of many patients
  • Failure to appreciate that environmental factors are vitally important in the prevention and treatment of delirium
  • Avoid sedating patients unless absolutely indicated.
  1. British Geriatrics Society. SIGN 157: Risk reduction and management of delirium. Clinical guidelines. 2019.
  2. National Institute for Health and Care Excellence. Delirium: prevention, diagnosis and management in hospital and long-term care. NICE [CG103], 2010. Last updated: 18 Jan 2023.
  3. MacLullich AMJ, Shenkin SD, Goodacre S, et al. The 4 ‘A’s test for detecting delirium in acute medical patients: a diagnostic accuracy study. Southampton (UK): NIHR Journals Library; 2019 Aug. (Health Technology Assessment, No. 23.40.) Chapter 1, General introduction.
  4. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th edn. Washington, DC: American Psychiatric Association; 2013.
  5. Hustey FM, Meldon SW. The prevalence and documentation of impaired mental status in elderly emergency department patients. Ann Emerg Med. 2002 Mar;39(3):248-53.
  6. Shenvi C, Kennedy M, Austin CA, Wilson MP, Gerardi M, Schneider S. Managing Delirium and Agitation in the Older Emergency Department Patient: The ADEPT Tool. Ann Emerg Med. 2020 Feb;75(2):136-145.
  7. Rapid Clinical Test for Delirium – 4AT
  8. British Geriatrics Society. 14. CGA in Primary Care Settings: Patients presenting with confusion and delirium. Good Practice Guide, 2019.
  9. Delirium. Royal College of Psychiatrists (RCPsych) Public Engagement Editorial Board, 2019.
  10. Young J, Inouye SK. Delirium in older people. BMJ. 2007 Apr 21;334(7598):842-6.
  11. Rudolph JL, Salow MJ, Angelini MC, McGlinchey RE. The Anticholinergic Risk Scale and Anticholinergic Adverse Effects in Older Persons. Arch Intern Med. 2008;168(5):508–513.
  12. Lonergan E, Mehta S, et al. Antipsychotics to treat delirium in hospitalised patients. Cochrane Database of Systematic Reviews 2018, Issue 6. Art. No.: CD005594.
  13. D’Souza RS, Hooten WM. Extrapyramidal Symptoms. [Updated 2023 Jan 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-.
  14. Siddiqui, N, Harrison JK, et al. Interventions to prevent delirium in hospitalised patients. Cochrane Database of Systematic Reviews 2016, Issue 3. Art. No.: CD005563.
  15. Mohr E, Mendis T, Hildebrand K, De Deyn PP. Risperidone in the treatment of dopamine-induced psychosis in Parkinson’s disease: an open pilot trial. Mov Disord. 2000 Nov;15(6):1230-7.