What type and dose of lidocaine (local anesthetic) is recommended for a digital block?

Lidocaine for Digital Block

For digital blocks, 1% lidocaine with epinephrine (1:100,000) is recommended at a volume of 2.5-5 mL per digit, not exceeding 7 mg/kg total dose. 1, 2

Type and Concentration of Lidocaine

• 1% lidocaine with epinephrine (1:100,000) is the preferred agent for digital blocks, providing adequate anesthesia with a duration of 90-200 minutes 1, 3
• Plain lidocaine (without epinephrine) can be used at 1-2% concentration but has a shorter duration of action (60-90 minutes) 1, 2
• The use of epinephrine in digital blocks is now considered safe in patients without vascular compromise, contrary to traditional teaching 3, 4

Dosing Recommendations

• Typical volume for digital block: 2.5-5 mL per digit 5, 4
• Maximum safe dose of lidocaine with epinephrine: 7 mg/kg (not to exceed 500 mg total) 1, 2
• Maximum safe dose of plain lidocaine: 4.5 mg/kg (not to exceed 300 mg total) 1, 2
• For children: 3.0-4.5 mg/kg with epinephrine; 1.5-2.0 mg/kg without epinephrine 1

Technique Considerations

• Digital blocks can be performed using dorsal or transthecal approaches 4
• Aspirate before injection to avoid intravascular administration 1
• Use the lowest effective volume to minimize risk of compartment syndrome 1
• Buffering lidocaine with sodium bicarbonate (1:9 or 1:10 ratio) can reduce injection pain 1

Alternative Options

• For longer procedures or extended postoperative analgesia:
  • 0.5% bupivacaine provides longer duration (180-600 minutes) but has a similar onset time to lidocaine 1, 6
  • 0.75% ropivacaine (2.5 mL) offers prolonged anesthesia (up to 21 hours) but has a slower onset (4.5 minutes vs 1.3 minutes for lidocaine) 5
• For patients with true lidocaine allergy (rare, <1% of adverse reactions):
  • Consider ester-type local anesthetics 1
  • 1% diphenhydramine can be used but has slower onset and limited efficacy 1
  • Bacteriostatic saline (0.9% benzyl alcohol in normal saline) is another alternative 1

Safety Considerations

• Signs of local anesthetic systemic toxicity (LAST) include circumoral numbness, facial tingling, slurred speech, metallic taste, auditory changes, and hallucinations 1
• Advanced LAST can progress to seizures, CNS depression, and cardiac arrest 1
• Reduce risk by using the lowest effective dose, aspirating before injection, and administering incremental injections 1
• The addition of epinephrine reduces the need for tourniquets and provides better hemostasis and longer pain control 3
• Avoid epinephrine in patients with thrombotic conditions, vasospastic disorders, or uncontrolled hypertension 3

Common Pitfalls

• Exceeding maximum recommended doses can lead to systemic toxicity 1
• Using excessive volumes can cause compartment syndrome 1
• Failing to aspirate before injection increases risk of intravascular administration 1
• Avoiding epinephrine unnecessarily (based on outdated dogma) may result in shorter anesthesia duration and poorer hemostasis 3, 4
• Using bupivacaine with sodium bicarbonate can cause precipitation and decreased efficacy 1

By following these recommendations, clinicians can provide safe and effective anesthesia for digital procedures while minimizing complications and optimizing patient comfort.