Caudal Epidural Block

Injection of LA into the epidural space:

Indications

Intra- and post-operative analgesia up to the umbilicus.

Contraindications

*This covers contraindications specific to caudal epidural anesthesia. General contraindications to neuraxial techniques are covered under principles of neuraxial anaesthesia.

Relative:

  • Abnormal sacral anatomy
    Pigmentation, dimples, and hair may be associated with spina bifida or a tethered cord - normal neuroanatomy should be confirmed prior.
  • Significance of motor weakness
    Often not done once mobilising or too big for a pram/stroller.

Anatomy

Predominantly a landmark technique. Identify:

  • Coccyx
    Identifies midline.
  • Posterior sacroiliac joints
  • Sacral cornuae
    Tubercles of the inferior articular processes.
    • Palpate cranial-caudal to identify the location of the ligament
      This should be located midline, at the point forming an equilateral triangle with each SI joint.

Equipment

  • Sterile preparation
  • Syringe
  • Needle
    • 25G to 23G needle
      Finer needles associated with IV or SAH injection.
  • Cannula
    Good alternative to needle.
    • Reduced incidence of dural puncture
    • Less likely to migrate during injection
    • 20G appropriate for most children
    • 22G if <8kg
    • 24G in premature babies

Drug prepration::

  • Local anaesthetic
    • 0.25% levobupivacaine
    • 0.2% ropivacaine
      Less motor block than levobupivacaine.
  • Additives
    • Clonidine 1.5μg/ml
      Prolongs caudal analgesia.
  • Total injectate volume determines block height:
    • Sacral: 0.5ml/kg
    • Lower thoracic: 1ml/kg
      Common dose used.
    • Upper thoracic: 1.25ml/kg
      May have significant cephalad spread.

Technique

Preparation

  • Obtain IV access
  • Apply ECG monitoring
  • Identify site

Procedure

  • Apply sterile preparation
  • Identify sacral hiatus
  • Cannulate sacral hiatus
    • Bevel facing posteriorly
    • Pop or loss of resistance should be felt as needle passes through sacrococcygeal membrane
    • Do not advance needle more than 2-3mm in space
  • Leave open to air to rule-out inadvertant IV or intrathecal placement With a cannula, this time can be used to draw up solution.
  • Perform aspiration test
  • Slowly inject selected dose

Post-Procedure

  • Ensure parents know to watch & return if:
    • Signs of weakness
    • Urinary retention
    • Local infection

Complications

  • Failure
    ~10%.
  • Urinary retention
  • Motor block
    Common and significant in older children.
  • Inadvertent dural puncture
  • Systemic LA toxicity

References