Pediatric Spinal Anesthesia Dosing with Bupivacaine
For pediatric spinal anesthesia, use bupivacaine 1 mg/kg in neonates and infants under 1 year of age, and 0.5 mg/kg in children over 1 year of age. 1
Age-Based Dosing Algorithm
Neonates and Infants (<1 year)
- Administer 1 mg/kg of hyperbaric bupivacaine 0.5% 1
- This dose provides approximately 60-90 minutes of surgical anesthesia 2, 3
- Expected sensory level: T4-T8 2
Children (>1 year)
- Administer 0.5 mg/kg of hyperbaric bupivacaine 0.5% 1
- For children 6-12 years, this produces analgesia duration of 4.5 hours with motor block lasting 2.5 hours 4
- Expected sensory level: T6-T10 4
Weight-Based Refinement (Alternative Approach)
If using weight-based dosing instead of age-based 2:
- <5 kg: 0.5 mg/kg
- 5-15 kg: 0.4 mg/kg
- >15 kg: 0.3 mg/kg
This approach achieved 97.1% success rate with minimal complications 2
Alternative Age-Based Formula
An alternative formula (age/5 = mg of bupivacaine) has been studied in children 2-12 years for infraumbilical surgeries, achieving sensory levels of T6-T10 with approximately 60 minutes of anesthesia duration 5. However, the ESRA/ASRA consensus recommendations should take precedence 1.
Tetracaine Alternative
For spinal anesthesia with tetracaine 0.5%, use 0.07-0.13 mL/kg 1. The maximum dose is 1.5 mg/kg with epinephrine or 1 mg/kg without epinephrine 6.
Critical Safety Considerations
Technical Success
- First attempt success rate: 58-70% 2, 3
- Overall success rate: 95-97% within 1-2 attempts 2, 3, 4
- Perform after surgeon is scrubbed to minimize delays 3
Hemodynamic Monitoring
- Bradycardia (<100 bpm) occurs in approximately 2% of cases without desaturation 3
- Hypotension is rare (2%) in pediatric patients 2
- High spinal block can occur (0.6%) but typically without hemodynamic compromise 3
Sedation Requirements
- Approximately 28% of children require supplemental IV sedation (midazolam 0.1-0.2 mg/kg) for crying or restlessness 3
- Some patients may need ketamine 0.25 mg/kg for additional calming 5
Common Pitfalls to Avoid
- Do not use weight-based dosing in older children - this leads to excessive doses; age-based dosing is more appropriate as the vertebral column grows with age, not weight 5
- Do not expect the same hemodynamic instability as adults - pediatric patients maintain cardiovascular stability remarkably well during spinal anesthesia 2, 3
- Do not delay attempting the block - have the surgeon ready to minimize time pressure 3
- Conversion to general anesthesia is rare (1-4%) but have equipment immediately available 2, 3
Expected Clinical Outcomes
Onset and Duration
- Sensory onset: 2-3 minutes 4
- Motor block onset: <3 minutes 4
- Two-segment regression time: 44 minutes 2
- Time to ambulation: 4 hours 4
- Complete motor recovery: 112 minutes 2
Block Characteristics
- Modified Bromage score of 3 achieved in 96% of patients 2
- Over 70% recover to Bromage 2-3 by surgery completion 4
- Sensory level typically T6-T8 at peak 2, 4