Acute deterioration in mental functioning arising over hours or days that is triggered mainly by acute medical illness, surgery, trauma, or drugs

Aetiology

• Most common mental heath problem in hospitalised patients over 65 years

Causes of delirium

• Drugs e.g. anticholinergic agents, anticonvulsants, alcohol, illicit drugs
• Withdrawal e.g. alcohol, sedatives (bensodiazapines)
• Metabolic e.g. AKI, hypoglycaemia, hypothyroid, B12/folate, calcium
• Electrolyte disturbance e.g. hyponatraemia, hypercalcaemia
• Infection
• Head trauma
• Epilepsy
• Reduced sensory input, pain
• Urinary retention/constipation
• Neoplastic diseases
• Vascular disorders

Risk factors

• Age - elderly patients
• Pre-existing cognitive impairment e.g. dementia
• Previous history of delirium
• Perioperative - long surgery, emergency surgery