What is the recommended spinal dose of local anesthetic (e.g. bupivacaine or ropivacaine) for children?

Spinal Anesthesia Dosing in Pediatric Patients

For spinal anesthesia in children, use hyperbaric bupivacaine at a dose calculated by the formula: age (in years) ÷ 5 = dose in mL of 0.5% hyperbaric bupivacaine, which provides reliable anesthesia for infraumbilical surgeries lasting approximately 60 minutes. 1

Evidence-Based Dosing Strategy

The "Partha formula" (age/5) has been validated in pediatric patients aged 2-12 years for infraumbilical procedures, achieving sensory levels between T6-T10 (mean T8.5) with no intraoperative complications or conversions to general anesthesia. 1 This age-based approach is physiologically sound because the vertebral column and spinal cord grow variedly with age rather than weight, making age-based dosing more appropriate than weight-based calculations for intrathecal administration. 1

Practical Application

• For a 5-year-old child: Administer 1 mL of 0.5% hyperbaric bupivacaine (5 mg) 1
• For a 10-year-old child: Administer 2 mL of 0.5% hyperbaric bupivacaine (10 mg) 1
• Puncture site: Must be performed at L4-L5 or L5-S1 spaces to prevent spinal cord injury 2

Key Pharmacologic Differences from Adults

Children require higher doses per kilogram of local anesthetics compared to adults, but paradoxically experience shorter duration of action and demonstrate greater hemodynamic stability. 2 This explains why the age/5 formula produces adequate but time-limited anesthesia suitable for procedures under 60 minutes. 1

Alternative Agents

While bupivacaine remains the most commonly used agent, tetracaine is also frequently employed for pediatric spinal anesthesia, either alone or with adjuvants. 2 However, the evidence base is strongest for hyperbaric bupivacaine using the age-based formula. 1

Critical Safety Considerations

• Success rate: First-attempt success occurs in 88% of cases; be prepared for a second attempt 1
• Sedation requirements: Approximately 12% of patients may require supplemental sedation (ketamine 0.25 mg/kg IV) for anxiolysis, not for inadequate anesthesia 1
• Failure rates: Published failure rates up to 28% emphasize that pediatric spinal anesthesia requires significant skill and experience 2
• Complications: Rare and typically without long-term consequences, though postdural puncture headache and backache can occur 2

Common Pitfalls to Avoid

• Do not use weight-based dosing for spinal anesthesia in children, as spinal anatomy correlates with age, not weight 1
• Do not puncture above L4-L5 to avoid spinal cord injury, as the conus medullaris extends lower in children 2
• Do not expect adult-duration anesthesia; plan for procedures lasting 60 minutes or less 1
• Do not confuse spinal dosing with epidural or peripheral nerve block dosing, which use entirely different volumes and concentrations (epidural lumbar: 0.5 mL/kg of 0.25% bupivacaine, maximum 15 mL) 3

When Spinal Anesthesia is Particularly Indicated

Spinal anesthesia is the preferred technique for high-risk patients and former preterm infants due to its protective role against postoperative apnea compared to general anesthesia. 2 Despite proven safety and efficacy, spinal anesthesia remains relatively underutilized in pediatric practice compared to general anesthesia. 2