Postoperative Delirium

Postoperative delirium is an acute, fluctuating disturbance of attention and cognition that appears within days of surgery, typically at 1 to 3 days. It is the commonest complication of surgery in older adults.

It occurs in about 15% to 25% of older patients after major surgery and in up to half after hip fracture or cardiac surgery.

Pathophysiology. Surgical stress and anaesthesia trigger neuroinflammation, with additional effects of pain, sleep loss, opioids, blood loss, hypoxia, electrolyte disturbance and urinary retention. Frailty, pre-existing cognitive impairment, sensory loss, polypharmacy and alcohol use increase risk.

Inattention, disorientation, fluctuation, agitation or lethargy, perceptual disturbance and altered sleep. It follows a lucid interval. Complications include falls, pressure injury, pneumonia, longer stay, loss of independence and long term cognitive decline.

Red flags.

• Focal deficit, seizure or sudden onset (stroke).
• Hypoxia, hypotension or sepsis.
• Anastomotic leak, bleeding or wound infection.

Screen daily with a validated tool for 3 days or more after surgery. Check observations, oxygen saturation, glucose, haemoglobin, electrolytes, renal function, culture results when infection is suspected, analgesia and drug charts, and bladder and bowel function. Image the brain for focal deficit or after a fall.

Differential diagnosis.

• Opioid toxicity and anticholinergic effect.
• Alcohol, benzodiazepine and nicotine withdrawal.
• Stroke, hypoxia, sepsis and pain.
• Hypoglycaemia and hyponatraemia.

Prevention is the best treatment: preoperative cognitive and frailty assessment, avoidance of benzodiazepines and anticholinergics, regional anaesthesia where suitable, minimal opioid doses with multimodal analgesia, early mobilisation, and sleep, hydration, nutrition, glasses and hearing aids. Treat established delirium by correcting causes. Use haloperidol 0.25 to 0.5 mg only for severe distress or danger to self.

Special groups. People with dementia need early geriatric co-management, familiar carers and a short fast track route through hospital.

Monitoring. Daily delirium screening until discharge.