What is the recommended technique and medication for a medial digital nerve block?

Medial Digital Nerve Block Technique and Medication

For medial digital nerve block, the recommended technique is a traditional digital block using bupivacaine 0.25% at a dose of 1-2 ml per side without epinephrine, which provides optimal duration of anesthesia with minimal risk. 1

Recommended Medications

First-line Agent:

• Bupivacaine 0.25%
  • Dose: 1-2 ml per side (not to exceed maximum dose of 2.5 mg/kg)
  • Duration: 180-600 minutes (3-10 hours)
  • Advantages: Longest-acting single-agent option 1, 2

Alternative Agents:

• Ropivacaine 0.2%

  • Dose: 1-2 ml per side (not to exceed maximum dose of 2.0 mg/kg)
  • Duration: 180-600 minutes (3-10 hours) 1
  • Advantages: Less cardiotoxic than bupivacaine

• Lidocaine 1-2%

  • Dose: 1-2 ml per side (not to exceed maximum dose of 4.4 mg/kg)
  • Duration: 90-200 minutes (1.5-3.3 hours) 1
  • Advantages: Faster onset (1-3 minutes vs 4-5 minutes for bupivacaine/ropivacaine) 3, 4

Technique for Medial Digital Nerve Block

1. Positioning:

   • Place the hand on a flat surface with palm down for dorsal approach
   • Or palm up for volar approach

2. Injection Sites:

   • Traditional approach: Two injection sites at the base of the digit, one on each side
   • Insert a 25-27G needle at the dorsolateral aspect of the base of the digit
   • Direct needle toward the volar surface along the side of the phalanx
   • Aspirate before injection to avoid intravascular administration

3. Volume and Administration:

   • Inject 1-2 ml of anesthetic solution per side
   • Withdraw needle partially and redirect to ensure complete circumferential spread

Important Considerations

Safety Precautions:

• Calculate maximum dose before administration to prevent toxicity 1
• Avoid epinephrine in digital blocks due to potential risk of ischemia, despite some recent evidence suggesting safety 5
• Monitor for signs of toxicity: circumoral numbness, facial tingling, slurred speech, metallic taste 1
• Have resuscitation equipment and 20% lipid emulsion available for treating local anesthetic toxicity 1

Technique Optimization:

• Consider buffering lidocaine with sodium bicarbonate (9:1 ratio) to reduce pain of injection if using lidocaine 6
• Thoroughly test block success before proceeding with procedure 7
• Allow adequate time for onset of anesthesia (1-3 minutes for lidocaine, 4-5 minutes for bupivacaine/ropivacaine) 3, 4

Special Populations:

• For pediatric patients, reduce doses by 30% in infants younger than 6 months 1
• For prolonged procedures (>1.5 hours), bupivacaine or ropivacaine is preferred over lidocaine 3

Bupivacaine 0.25% provides the longest duration of anesthesia (average 24.9 hours) compared to lidocaine with epinephrine (10.4 hours) or plain lidocaine (4.9 hours), making it ideal for procedures requiring extended post-operative pain control 2.