Emergence delirium short note for md anaesthesia exam .
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Emergence Delirium - Short Note for MD Anaesthesia
Definition
Emergence delirium (ED) is a dissociative state of consciousness occurring in the first 15-30 minutes after emergence from general anaesthesia, characterized by altered cognition, reduced awareness of the environment, perceptual disturbances, and psychomotor agitation. It is distinct from postoperative delirium (which develops later, over hours to days) and from inadequately treated pain.
Incidence
- Predominantly a paediatric phenomenon - incidence 10-80% in children
- Highest in preschool children aged 2-7 years (peak around 3-5 years)
- Adult incidence is much lower but under-recognized
- More frequent after ENT and ophthalmologic procedures
Clinical Features
ED typically manifests as:
| Feature | ED | Pain |
|---|---|---|
| Eye contact with caregiver | Absent | Present |
| Awareness of surroundings | Absent | Present |
| Purposeful activity | Absent | May be present |
| Inconsolability | Present | Present |
| Facial expression / crying | May be absent | Prominent |
The child may thrash, kick, scream, and be completely unresponsive to the parents' voice or touch. It is self-limited, lasting typically 5-20 minutes, but can cause IV catheter dislodgement, surgical site bleeding, patient or staff injury, and caregiver distress.
Two phenotypes exist:
- Hyperactive (most common): agitation, thrashing, inconsolability
- Hypoactive (less recognized): inactivity, unresponsiveness - less risk of injury but still delirium
Pathophysiology
The definitive etiology is unknown. Proposed mechanisms:
- Premature or dissociated arousal - incomplete recovery of brain network connectivity on awakening, particularly in frontal lobe networks. EEG studies show increased frontal brain region connectivity in children with ED, suggesting emergence from an intermediate state of consciousness without complete brain integration.
- Volatile anaesthetic effect - sevoflurane and desflurane strongly associated; likely related to rapid offset allowing partial awakening before full cortical integration
- Rapid emergence - sudden restoration of awareness without adequate sensorimotor integration
- GABA-receptor theory - residual effect of volatile agents on GABAergic and cholinergic systems
Risk Factors
Patient factors:
- Age 2-7 years
- Preoperative anxiety (patient and caregiver)
- Pre-existing maladaptive/behavioural problems
- Baseline anxious temperament
- Negative behaviour during induction
Anaesthetic factors:
- Volatile maintenance (especially sevoflurane, also desflurane)
- Rapid emergence from anaesthesia
Surgical factors:
- Ophthalmology procedures (highest risk)
- Otorhinolaryngology (adenotonsillectomy, etc.)
- Prolonged or painful surgery
Assessment - PAED Scale
The Pediatric Anesthesia Emergence Delirium (PAED) scale (Sikich & Lerman, 2004) is the validated scoring tool:
| Item | Not at all | Just a little | Quite a bit | Very much | Extremely |
|---|---|---|---|---|---|
| Makes eye contact with caregiver | 4 | 3 | 2 | 1 | 0 |
| Actions are purposeful | 4 | 3 | 2 | 1 | 0 |
| Aware of surroundings | 4 | 3 | 2 | 1 | 0 |
| Child is restless | 0 | 1 | 2 | 3 | 4 |
| Child is consolable | 0 | 1 | 2 | 3 | 4 |
Total score 0-20. Score ≥ 10 is diagnostic of ED.
Key differentiating point: absence of eye contact + lack of awareness of surroundings = ED. Crying, abnormal facial expression, and inconsolability alone are more suggestive of pain.
Differential Diagnosis of PACU Agitation
Must exclude before labelling ED:
- Pain (most common confounder)
- Urinary retention / full bladder
- Hypoxia / hypercarbia
- Hypoglycaemia / metabolic derangement
- Hyponatraemia
- Residual neuromuscular blockade
- Restrictive casts, tight bandages
- Parental separation anxiety / "tantrum"
Prevention
Preoperative
- Treat preoperative anxiety with play therapy, distraction, parental presence at induction
- Ketamine premedication - shown benefit
- Melatonin premedication - shown some benefit
- Midazolam premedication - NOT shown to reduce ED
Intraoperative
| Strategy | Evidence |
|---|---|
| Propofol TIVA (instead of sevoflurane) | Strong - ED rare after TIVA |
| Dexmedetomidine IV 0.5-1 mcg/kg | Meta-analyses confirm reduction; decreases incidence from 47% to 2.8% (alpha-2 agonists oral/IV/caudal all effective) |
| Propofol 2-3 mg/kg bolus prior to emergence | Effective |
| Fentanyl (opioid analgesia) | Effective - pain control reduces ED |
| Clonidine | Effective (alpha-2 agonist) |
| Adequate analgesia throughout | Essential |
Note: Dexmedetomidine in a RCT at 0.5 mcg/kg following induction reduced ED from 53.3% (placebo) to 31.1% in 2-7 year olds undergoing tonsillectomy with sevoflurane maintenance (Barash, Clinical Anesthesia 9e).
Processed EEG depth of anaesthesia monitoring has not been shown to correlate with or prevent ED incidence in the paediatric population.
Treatment
When ED occurs in the PACU:
- Ensure safety - padded cot sides, close monitoring, prevent IV/surgical site dislodgement
- Exclude and treat reversible causes - pain (administer appropriate analgesia), hypoxia, urinary retention
- Parental presence - allow parents in PACU if feasible
- Pharmacological treatment (if persistent / high PAED score):
| Drug | Dose | Notes |
|---|---|---|
| Dexmedetomidine (first line) | 0.5 mcg/kg IV | Analgesic + antiemetic + sedative effects |
| Propofol | 0.5-1 mg/kg IV | Rapid but short-acting |
| Opioids (fentanyl/morphine) | Titrated doses | If pain component |
| Physostigmine | 0.02-0.04 mg/kg IV | Evidence limited; may help in anticholinergic component |
| Midazolam | Variable | Evidence poor for ED specifically |
Dexmedetomidine is the preferred first-line agent due to demonstrated efficacy, additional analgesic properties, and antiemetic effects (Miller's Anaesthesia 10e, Barash 9e).
Complications
- Accidental IV cannula removal
- Dislodgement of monitoring devices / drains
- Bleeding from or injury to surgical site
- Patient and provider injury
- Persistent negative postoperative behavioural changes (night terrors, separation anxiety, enuresis)
- Prolonged PACU stay
- Unplanned hospital admission
Key Exam Points
- ED is not simply pain - PAED scale distinguishes the two; absence of eye contact and awareness are hallmarks
- Sevoflurane > desflurane > halothane in propensity to cause ED; propofol TIVA essentially eliminates it
- PAED score ≥ 10 = ED; max score 20
- Dexmedetomidine is both the best preventive and therapeutic agent
- Midazolam premedication does NOT prevent ED (common exam trap)
- Ketamine and melatonin premedication have shown benefit
- Adult ED exists but is less common; same principles apply
- The condition is self-limited (5-20 min) but requires active management to prevent morbidity
Sources:
- Barash, Cullen & Stoelting's Clinical Anesthesia, 9e, Chapter 43 (PACU, Pediatric Complications)
- Miller's Anesthesia, 10e, Chapter 72 (Pediatric Anesthesia)
- Cummings Otolaryngology Head and Neck Surgery, Chapter 184
- Sikich N, Lerman J. Development and psychometric evaluation of the PAED scale. Anesthesiology 2004;100(5):1138-1145
- ESAIC updated postoperative delirium guidelines 2024 (PMID: 37599617)
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