Caudal block

 

Background knowledge:

Anatomy

Sacral hiatus:

·      Triangular gap between sacrum and coccyx

·      Two cornua at the base, median crest at the apex

·      Covered by sacrococcygeal ligament (= ligamentum flavum)

Neuraxis:

·      Epidural space is underneath the ligament

·      Epidural-spinal distance is 1cm in neonates, 3cm in adults

·      N.B. injectate leaks out to bathe sacral nerves; hence long duration

Landmarks:

·      Imaginary south-pointing equilateral triangle

·      Two PSIS at the base

·      Sacral hiatus at the apex

Contraindications

Practical:

·      Child >20kg (carry limit)

Medical:

·      Coagulopathy

·      Localised infection

·      Spinal malformation

·      Neurological disorder

Complications

Needle:

·      Too shallow: failure

·      Too deep: dural puncture, high spinal

·      Too far south: rectal perforation

·      In nerve: catastrophic damage

·      In vessel: LAST, epidural haematoma

·      In marrow: LAST

Block:

·      Urinary retention

·      Respiratory depression (if opioid)

·      High block

 

Procedure:

Equipment

·      Sterile regional kit

·      Sterile gloves

·      0.5% Chlorhexidine / 70% alcohol lollipop

·      0.5% bupivacaine

·      20mL syringe

·      21g needle

Monitoring

·      Sat probe

·      NIBP

·      ECG (risk of LAST)

Positioning

·      Left lateral decubitus

·      Spine, hips, knees flexed

Mechanics

·      Palpate cornua with thumb of other hand

·      Pierce skin at 60 degrees

·      Flatten out to 30 degrees

·      Advance until ‘pop’

·      Aspirate for blood

·      Inject

Dose

Bupivacaine:

·      0.5mL/kg circumcision

·      0.75mL/kg herniorraphy

·      1mL/kg orchidopexy – go to dose

Additives:

·      Clonidine 1-2mcg/kg

 

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