What is the best technique for a digital ring block?

Best Technique for Digital Ring Block

The traditional dorsal digital block is the recommended technique for digital ring block due to its high success rate, complete anesthesia coverage, and established safety profile. 1

Anatomy and Principles

• Digital nerves include two dorsal digital nerves (radial and ulnar aspects) and two volar digital nerves (radial and ulnar aspects)
• Complete digital anesthesia requires blocking all four nerves
• Proper technique minimizes pain while maximizing anesthetic distribution

Recommended Technique: Traditional Dorsal Digital Block

Equipment

• 1% lidocaine without epinephrine (3-5 mL)
• 25-27 gauge needle
• Sterile preparation supplies

Procedure Steps

1. Position the patient's hand with palm facing down
2. Identify the web space at the base of the finger
3. Insert the needle at the dorsal web space between the target finger and adjacent finger
4. Advance the needle to the volar aspect without penetrating too deeply
5. Aspirate to ensure no intravascular placement
6. Inject 1-2 mL of anesthetic
7. Repeat on the opposite side of the digit
8. Wait 1-3 minutes for complete anesthesia before beginning procedure

Anesthetic Selection

• First choice: 1% lidocaine without epinephrine
  • Onset: 1-3 minutes
  • Duration: 1.5-2.5 hours
  • Maximum dose: 4-5 mg/kg (not to exceed 300 mg total) 1
• For longer procedures (>1.5 hours): Consider 0.75% ropivacaine
  • Onset: 3.5-5.5 minutes
  • Duration: 19-23 hours 1

Alternative Techniques

Single Injection Techniques

• Volar Subcutaneous Block: Single injection at the volar aspect of the digit base

  • Advantages: Single injection, less painful
  • Limitations: May not reliably anesthetize dorsal proximal phalanx 2

• Transthecal Block: Injection into the flexor tendon sheath at the palmar digital crease

  • Advantages: Single injection, rapid onset
  • Limitations: More technically challenging, risk of tendon injury 3, 4

• Combined Technique: Combination of subcutaneous and transthecal approaches

  • Advantages: Highest rate of complete digital block
  • Limitations: More invasive 2

Important Safety Considerations

• NEVER use epinephrine-containing solutions in digits due to risk of ischemia and necrosis 5, 1
• Use sterile technique to avoid introducing infection
• Do not perform blocks through infected or severely burned tissue
• Monitor distal circulation after the block, especially with circumferential injuries
• Do not exceed maximum recommended doses of local anesthetics
• Consider adding sodium bicarbonate to reduce pain of local anesthetic infiltration 5

Efficacy Comparison

A systematic review and meta-analysis found no significant differences in time to anesthesia, duration of anesthesia, and pain of injection between different digital nerve block techniques 6. However:

• Traditional dorsal approaches provide better coverage of the proximal dorsal surface 6
• Single-injection volar approaches may be preferred by patients due to less pain 6, 7
• Success rates range from 60% to 100% depending on technique 7

Clinical Pearls

• Test block success before beginning procedure by checking sensation in all areas of the digit
• When performing the dorsal approach, keep the needle superficial to avoid digital artery puncture
• For procedures involving the dorsal aspect of the proximal phalanx, the traditional dorsal approach is preferred
• For procedures limited to the volar aspect or distal/middle phalanges, single injection techniques may be adequate

The traditional dorsal digital block remains the gold standard for digital anesthesia due to its reliability in providing complete anesthesia of the entire digit with minimal complications.