Digital Nerve Block: Bupivacaine Selection
For finger blocks in adults, use plain bupivacaine 0.25% without epinephrine, as this concentration provides reliable sensory anesthesia with minimal motor blockade and an acceptable safety profile for peripheral nerve blocks. 1
Concentration and Formulation
- Bupivacaine 0.25% is the standard concentration recommended by the European Society for Paediatric Anaesthesiology for peripheral nerve blocks, including digital blocks 1
- This concentration consistently produces complete sensory anesthesia while minimizing motor blockade 2
- Higher concentrations (0.5% or 0.75%) are unnecessary for digital blocks and increase toxicity risk without improving analgesia for this application 2
Alternative Formulations
If bupivacaine 0.25% is unavailable, acceptable alternatives include:
- Levobupivacaine 0.25%: Equivalent efficacy with potentially reduced cardiac toxicity risk 1, 3
- Ropivacaine 0.2%: Slightly less potent but with improved safety profile; may require marginally higher volumes 1, 3
The clinical differences between these three agents are minimal in practice, with the main distinction being slightly different anesthetic potency (bupivacaine > levobupivacaine > ropivacaine) 3
Volume and Dosing
- For adults: Use 2-4 mL total volume per digit, divided between the two digital nerves 4
- Maximum safe dose: Do not exceed 2.5 mg/kg total dose (equivalent to 1 mL/kg of 0.25% solution) 1
- For a 70 kg adult, this translates to a maximum of 175 mg or 70 mL of 0.25% bupivacaine 1
Critical Safety Considerations
- Never use epinephrine-containing solutions in digital blocks due to risk of digital ischemia from end-artery vasoconstriction 4
- Always aspirate before injection to avoid intravascular administration and systemic toxicity 5
- Calculate total dose in mg/kg, especially when blocking multiple digits, to prevent exceeding toxic thresholds 1, 5
Technique-Specific Notes
The traditional subcutaneous infiltration technique (dorsal approach at the base of the digit) is preferred over transthecal blocks, as it causes significantly less pain during injection (mean pain score 1.6 vs 3.2) and fewer post-procedure complications 6