What is the recommended dose of bupivacaine (local anesthetic) for a caudal block?

Recommended Dose of Bupivacaine for Caudal Block

For caudal blocks in children, the recommended dose of bupivacaine 0.25% is 1.0 ml/kg. 1

Dosing Guidelines for Caudal Block

• Bupivacaine 0.25%: 1.0 ml/kg 1
• Levo-bupivacaine 0.25%: 1.0 ml/kg 1
• Ropivacaine 0.2%: 1.0 ml/kg 1

Maximum Dose Considerations

• The maximum dose of bupivacaine 0.25% for peripheral nerve blocks and wound infiltration is 1 ml/kg (equivalent to 2.5 mg/kg) 1
• This maximum dose should not be exceeded when performing caudal blocks to prevent local anesthetic toxicity 1

Adjuvants for Caudal Block

When appropriate and with adequate monitoring, the following adjuvants can be added to enhance and prolong the analgesic effect:

• Preservative-free clonidine: 1 to 2 micrograms/kg 1
• Morphine: 30 to 50 micrograms/kg (only with adequate monitoring for respiratory depression) 1

Volume-Concentration Considerations

• The standard recommendation of 1.0 ml/kg of 0.25% bupivacaine provides optimal spread for procedures requiring mid-to-lower abdominal coverage 1
• For perineal surgery, a lower volume (0.5 ml/kg) may be sufficient 2
• For higher abdominal procedures requiring more cephalad spread, volumes up to 1.25 ml/kg may be needed 2

Clinical Pearls and Caveats

• The spread of local anesthetic in caudal blocks is age-dependent, with younger patients (especially infants <12 months) typically experiencing more extensive cephalad spread for the same volume/kg 2
• Using a larger volume of a more dilute solution (e.g., 1.0 ml/kg of 0.2%) may provide better blockade of peritoneal response during procedures like orchidopexy compared to smaller volumes of more concentrated solutions 3
• Ropivacaine 0.2% at 1.0 ml/kg provides similar analgesic efficacy to bupivacaine 0.25% but with less motor blockade, which may be advantageous for ambulatory procedures 4
• Volumes less than 0.75 ml/kg may result in inadequate analgesia for procedures like herniotomy 5

Continuous Caudal Infusion

For continuous caudal analgesia with adequate monitoring:

• Continuous rate of bupivacaine 0.25%: 0.1-0.3 ml/kg/h 1
• Preservative-free clonidine can be added at 0.2 to 0.4 micrograms/kg/h 1

Safety Considerations

• Always calculate the total dose in mg/kg to ensure it remains below the toxic threshold
• Consider the patient's age, as infants may be more sensitive to local anesthetics
• Ensure appropriate monitoring for potential complications
• Aspirate before injection to avoid intravascular administration
• Consider using a test dose with epinephrine to detect intravascular injection