FRCA Notes

Paediatric Regional Anaesthesia & Analgesia

The curriculum asks us to provide 'correct postoperative pain management, including the use of regional and local anaesthetic techniques' in paediatric patients.

Resources

  • Regional anaesthesia can provide excellent post-operative analgesia in children, and should be used as part of a multi-modal analgesic approach
Benefits of regional anaesthesia in paediatrics
↓ exposure to general anaesthetic agents
Improved haemodynamic stability
↓ PONV
Earlier return of gut function and feeding
↓ opioid use
↓ post-operative pain scores
↓ incidence of respiratory complications
Suppresses stress response
May prevent long-term behavioural responses to pain
May reduce risk of chronic post-surgical pain


Difference Clinical implication
Nerves, vessels and tendons are smaller, more superficial,
more compact and with less adipose tissue		 Higher risk of injury to nerves and structures
Ultrasound a must; associated with ↓ needle passes and better outcomes
Endoneurium has less connective tissue
Nerves are smaller diameter
Nerves have incomplete myelin sheaths		 Early onset sensory and motor block
Risk of prolonged motor block even with low concentrations of LA
The dural sac ends at S3–S4 (S2 by 2yrs as in adults)
The intercristal line is at L5-S1 (L4–L5 in older children and adults)
Spinal cord terminates at L3 (L1 in adults) 		Care during caudal epidural to avoid dural puncture
Perform spinals below L4
Thoracic spinous processes less caudally angulated in neonates Altered needle trajectory
Absence of thoracic kyphosis Greater cephalad spread of drugs
Higher CSF volume in neonates (4ml/kg) than adults (2ml/kg)
Higher cardiac output Faster systemic absorption
Shorter block duration
Higher proportion of cardiac sodium channels are in open state ↑ risk of cardiac toxicity
Hepatic metabolism of LA is not fully functional until 9 months
↓ ɑ1-acid glycoprotein levels until 1yr		 Higher risk of drug accumulation with repeated doses or infusions
Lumbar sympathetic component immature in children Less prone to hypotension, vasoplegia or cardiovascular instability after neuraxial block


  • Benefits as above, as well as avoiding ventilation in a population which may have increase airway reactivity or lung disease associated with prematurity

  • Options include:
    • Spinal anaesthesia
    • Thoracic epidural
    • Lumbar epidural
    • Caudal epidural (see separate page)

Spinal anaesthesia

  • Spinal anaesthesia may be used for inguinal, urological, and lower limb surgery
  • Often uses 0.5% heavy bupvacaine;
    • Weight <5kg; 1ml/kg
    • Weight 5-15kg; 0.4ml/kg
    • Weight >15kg; 0.3ml/kg
  • 0.5% tetracaine is another option

  • Due to anatomical and physiological differences, only 45-60mins anaesthesia is achievable without the use of adjuncts
  • Associated with reduced frequency of early post-operative apnoea and fewer severe apnoea events (but no overall difference in risk of any apnoea within 12hrs)

Epidural anaesthesia

  • Generally performed asleep
  • Radiological assessment of epidural LA spread in babies <5kg demonstrates high variability in quantity & extent of spread, with filling defects & skipped segments being common
  • Depth to the epidural space can be assessed with ultrasound, which may be easier than in adults due to incomplete ossification (or one can use the '1mm/kg' rule of thumb)
  • Epidurography, ECG guidance, nerve stimulation, and ultrasound may all be used to assess the position of the catheter tip
  • Patients with epidural catheters in situ should be reviewed daily by an acute pain service and through the transition to systemic analgesia

  • Essentially the same gamut of regional anaesthetic options exist for paediatric patients as they do for adults
  • Local anaesthetics include (levo)bupivacaine 0.25% or ropivacaine 0.2%
  • The indications for upper and lower limb blocks generally mirror those in adults

Upper limb

Block Volume of LA
Supraclavicular 0.5-1.5ml/kg
Axillary 0.5-1.5ml/kg
Forearm nerves 0.5-0.6ml/kg

Lower limb

Block Volume of LA
Femoral nerve 0.5-1.5ml/kg
Lateral femoral cutaneous nerve 0.5-1ml/kg
Saphenous nerve
(subsartorial or adductor canal approaches)		 0.5-1ml/kg
Obturator nerve 0.5-0.75ml/kg
Sciatic nerve at the popliteal fossa 0.5-1.5ml/kg

Thorax and abdomen

Block Indications Volume of LA
Paravertebral Pectus excavatum repair (Nuss/Ravitch procedures)
Thoracotomy		 0.1-0.2ml/kg
Serratus anterior plane Coarctation repair
Thoracoscopy
Nuss procedure
Lateral chest wall surgery		 0.4ml/kg of 0.125%
Pecs 1/2 Anterior chest wall surgery 0.15-0.3ml/kg
Transversus abdominis plane Intra-abdominal surgeries 0.2-0.5ml/kg
Rectus sheath Anterior abdominal wall incisions 0.2-0.5ml/kg
Ilioinguinal/iliohypogastric Inguinal hernia repair 0.1-0.2ml/kg
Pudendal nerve Any indication for caudal epidural 0.3-0.4ml/kg

Local anaesthetics

  • Bupivacaine 0.25%
  • Levobupivacaine 0.25%
  • Ropivacaine 0.2%

Adjuncts

  • Advanatages of using adjuncts in blocks include:
    • Prolongs duration of analgesia (>50%) without increasing motor blockade
    • Earlier block onset
    • Reduced LA dose and therefore risk of LAST
    • Reduced use of opioid analgesia

  • However, one must be aware of issues such as prolonged sedation/apnoea, hypotension & bradycardia, delayed discharge or masked compartment syndrome (see below)
  • Naturally adjuncts should be of the preservative-free variety
Adjuncts in paediatric regional anaesthesia
Morphine (10-30μg/kg for neuraxial block)
Clonidine (1-2μg/kg)
Dexmedetomidine (1-2μg/kg)
Ketamine (0.5mg/kg, not intrathecally)
Fentanyl (e.g. 0.2μg/kg for spinal )
Diamorphine
Adrenaline (2-4μg/kg for neuraxial block)


  • The overall rate of complications for regional anaesthesia in the paediatric population is in the region of 0.1% (0.09 - 0.12%)
    • The complication rate may be higher for caudal /epidural techniques alone (0.66%)
  • The most common issue is technical i.e. failure to establish or maintain the block

  • Other complications:
    • Prolonged motor block
    • Urinary retention
    • Catheter-associated issues e.g. leaking, occlusion, disconnection, displacement/removal (4%)
    • Transient neurological deficit (0.024%)
    • Serious adverse events are rare (0.01%) e.g. nerve injury, LAST, infection, pressure area injury

Local anaesthetic toxicity

  • Very rare (incidence 0.76 - 1.6 per 10,000)
  • Methods to reduce risk include:
    • Continuous monitoring including ECG
    • Strict compliance with recommended LA doses
    • Gentle aspiration prior to injection, with subsequent slow and fractionated injection
    • Avoid conditions enhancing toxicity e.g. hypoxaemia, acidaemia and hypercarbia

  • Management is similar for adult local anaesthetic toxicity
    • ABCDE
    • Treat hypotension with ephedrine e.g. 1μg/kg
    • Treat seizures with benzodiazepines e.g. midazolam 0.05-0.1mg/kg/min
    • Administer intralipid
      • 1.5ml/kg bolus
      • 0.25ml/kg/min infusion, increased by 0.5ml/kg/min if cardiovascular stability not restored
      • Repeat bolus dose every 5 mins
      • Max dose 10ml/kg

Compartment syndrome

  • Some concern that regional anaesthesia in trauma patients may mask symptoms of compartment syndrome, thus delaying diagnosis and treatment
  • The incidence of compartment syndrome in children (0.02%) is lower than that of adults
  • No convincing evidence that regional anaesthesia complicates the diagnosis of acute compartment syndrome if patients are adequately monitored and assessed
  • Methods to reduce the risk of masking compartment syndrome include:
    • Using low concentrations of local anaesthetics for blocks and continuous infusions e.g. 0.1% levobupivacaine/ropivacaine
    • Restrict both volume and concentration of LA in high risk surgeries e.g. tibial compartment surgery
    • Being cautious with use of adjuncts in this patient cohort, as they increase block density and duration
    • Regular monitoring
    • Follow-up by an acute pain service
    • Ability to monitor compartment pressures

Awake vs asleep blocks

  • Awake blocks benefit from early detection of LAST and reduced risk of intra-neural injection and its negative sequelae
  • However, they suffer from impracticality and a potential increased risk of failure or harm
  • Generally felt that asleep blocks are acceptable given the prolonged safety record of doing so