Emergence Delirium

Emergence delirium is an acute disturbance of attention, awareness and cognition on waking from general anaesthesia, with agitation, disorientation, thrashing and inconsolable crying in children. It is usually brief (5 to 30 minutes) and self-limited.

Epidemiology. In children it affects about 10% to 30% overall (up to 80% in some series) and peaks at ages 2 to 6 years. In adults it affects about 5% to 20%. It is commoner after sevoflurane and desflurane.

Risk factors. Preschool age, preoperative anxiety, ENT, ophthalmic and dental surgery, rapid emergence, pain, full bladder, hypoxia and, in adults, older age, preexisting cognitive impairment, benzodiazepines, anticholinergics and alcohol use.

Pathophysiology.

The mechanism is unclear. Contributors are rapid, uneven recovery of cortical function, residual agent effects on neurotransmitters, pain and anxiety. Emergence delirium is distinct from postoperative delirium, which appears hours to days later.

Agitation, thrashing, non-purposeful movement, lack of eye contact, disorientation, failure to recognise parents, tearfulness, combative behaviour, pulling at lines and risk of injury.

Red flags.

• Hypoxia, airway obstruction or laryngospasm.
• Severe pain.
• Hypoglycaemia.
• Agitation persisting over 30 minutes or relapse after calm.
• Focal neurological signs.

Score with the Paediatric Anaesthesia Emergence Delirium scale (a score of 10 or more is positive) in children, and with the Richmond Agitation-Sedation Scale or Confusion Assessment Method in adults. Exclude pain, hypoxia, hypercapnia, hypoglycaemia, full bladder, nausea and drug withdrawal.

Differential diagnosis.

• Pain.
• Hypoxia.
• Hypercapnia.
• Hypoglycaemia.
• Urinary retention.
• Residual anaesthetic effect.
• Alcohol or drug withdrawal.
• Anticholinergic toxicity.

Treat the cause, ensure safety, give analgesia, and reunite the child with a parent in a quiet area.

• Dexmedetomidine (prevention or treatment): 0.3 microgram/kg IV over 10 minutes at the end of surgery in children, 0.2 to 0.5 microgram/kg in adults; single dose; maximum 1 microgram/kg in this use; monitor heart rate, blood pressure and sedation; reduce in older adults and hepatic impairment; avoid in heart block.
• Propofol (rescue): 0.5 to 1 mg/kg IV, repeated once; maximum 2 mg/kg cumulative; monitor airway and blood pressure; reduce in older adults and shock.
• Fentanyl (pain related): 0.5 to 1 microgram/kg IV, repeated once after 5 minutes; maximum 2 microgram/kg; monitor respiratory rate and saturation; reduce in older adults and hepatic impairment.
• Paracetamol: 15 mg/kg IV or orally in children every 6 hours, maximum 60 mg/kg in 24 hours (neonates need lower doses); adults 1 g every 6 hours, maximum 4 g in 24 hours; reduce with hepatic impairment or malnutrition.

Prevention. Reduce preoperative anxiety, use a propofol dose of 1 mg/kg at the end of sevoflurane anaesthesia, give analgesia before emergence, avoid sevoflurane at high concentration in at risk children, and consider total intravenous anaesthesia for high risk patients.

Monitoring. Emergence scores every 5 to 15 minutes, saturation, heart rate, pain and glucose when unexplained.

Referral and escalation. Senior anaesthetic review if over 30 minutes or if a neurological cause is suspected. Geriatric or psychiatric review for adults with persistent delirium.

Special groups. Preschool children need parental presence. Older adults need delirium prevention and avoidance of benzodiazepines.