Delirium

Definition

Delirium is an acute, often fluctuating, state of confusion characterised by altered consciousness and cognition. It can develop rapidly and is typically reversible if the underlying cause is identified and treated promptly.

Aetiology

Delirium can be caused by a variety of factors, including:

• Infections (e.g., urinary tract infections, pneumonia)
• Medications (e.g., sedatives, anticholinergics)
• Metabolic imbalances (e.g., electrolyte disturbances, hypoglycaemia)
• Alcohol withdrawal
• Surgery and anaesthesia
• Severe illness or injury
• Dehydration

Pathophysiology

Delirium results from a complex interplay of factors leading to altered neurotransmitter activity, particularly involving acetylcholine and dopamine. This disruption affects brain function, leading to the characteristic cognitive and behavioural disturbances.

Risk Factors

• Advanced age
• Pre-existing cognitive impairment or dementia
• Severe illness or multi-morbidity
• Polypharmacy
• Sensory impairments (e.g., poor vision or hearing)
• Alcohol or drug abuse

Signs and Symptoms

• Acute onset of confusion
• Fluctuating levels of consciousness
• Disorganised thinking
• Hallucinations or delusions
• Agitation or lethargy
• Sleep disturbances
• Inattention

Investigations

• Clinical assessment, including history and physical examination
• Blood tests (e.g., full blood count, electrolytes, glucose, renal and liver function tests)
• Urine analysis and culture
• Chest X-ray if respiratory infection is suspected
• Medication review to identify potential causes
• CT or MRI of the brain if structural abnormalities are suspected

Management

Primary Care Management

• Identify and treat underlying causes (e.g., infections, metabolic imbalances)
• Provide supportive care, including hydration and nutrition
• Ensure a safe environment to prevent harm
• Reorient the patient regularly and ensure the presence of familiar objects
• Avoid or minimise the use of sedatives and antipsychotics unless absolutely necessary

Specialist Management

• Referral to a geriatrician, neurologist, or psychiatrist for complex cases
• Comprehensive geriatric assessment for older adults
• Management of severe agitation or behavioural disturbances with low-dose antipsychotics (e.g., haloperidol), only if non-pharmacological measures fail and the patient is at risk of harm
• Consideration of ICU care for severely ill patients

Example Management for Delirium

A patient presenting with acute confusion and suspected delirium should undergo a thorough clinical assessment, including a review of medications and screening for infections and metabolic imbalances. Initial management should focus on treating identified causes, such as starting antibiotics for a urinary tract infection and correcting electrolyte disturbances. Supportive care includes ensuring adequate hydration, nutrition, and a safe environment. If the patient is severely agitated and at risk of harm, low-dose haloperidol may be considered, but regular monitoring and review are essential.

References

1. NICE. (2024). Delirium: Prevention, Diagnosis, and Management. Retrieved from NICE
2. NHS. (2023). Delirium. Retrieved from NHS
3. Inouye, S. K., Westendorp, R. G. J., & Saczynski, J. S. (2014). Delirium in Elderly People. The Lancet.
4. Marcantonio, E. R. (2017). Delirium in Hospitalized Older Adults. New England Journal of Medicine.
5. Young, J., & Inouye, S. K. (2007). Delirium in Older People. BMJ Clinical Evidence.