What is the procedure for performing a digital block on a pinky finger?

Digital Block Procedure for the Pinky Finger

A digital nerve block of the pinky finger should be performed using a single-injection technique with lidocaine (with or without epinephrine), injected at the base of the digit to anesthetize all four digital nerves, as this approach is safe, effective, and minimizes patient discomfort compared to traditional multi-injection ring blocks. 1, 2

Recommended Technique Options

Single-Injection Transthecal Approach (Preferred for Simplicity)

• Insert a 25-gauge needle at the palmar flexion crease at the base of the digit, directing it into the flexor tendon sheath at the midpoint between the proximal digital crease and the proximal interphalangeal joint crease 3
• Inject 2-3 mL of 1% lidocaine (or a 1:1 mixture of 1% lidocaine and 0.5% bupivacaine for prolonged effect) into the flexor tendon sheath 4, 3
• The anesthetic diffuses centrifugally through the sheath to anesthetize all four digital nerves rapidly 3
• This technique has demonstrated 94% success rate in pediatric populations and near 100% success in adults 4, 3

Tumescent Single-Injection Technique (Alternative)

• Inject 1% lidocaine into the volar subcutaneous space at the proximal digit until the tissue becomes firm and turgid (tumescent state) 5
• Volume should be adjusted based on digit size, typically 2-3 mL for an adult pinky 5
• This approach achieved 100% success rate in 123 consecutive patients with no adverse events 5

Anesthetic Selection

Lidocaine as Primary Agent

• Use 1% lidocaine as the standard anesthetic, as it is FDA-approved for peripheral nerve blocks and provides reliable digital anesthesia 2
• Plain lidocaine provides adequate anesthesia for most procedures 6

Addition of Epinephrine (Safe and Beneficial)

• Epinephrine can be safely added to lidocaine for digital blocks, contrary to historical teaching 7
• Adding epinephrine prolongs anesthesia duration by 3.2 hours (95% CI 2.48-3.92 hours) and reduces intraoperative bleeding (risk ratio 0.35,95% CI 0.19-0.65) 7
• No cases of digital ischemia or gangrene have been reported in modern studies when epinephrine is used appropriately 7

Extended Duration Option

• Consider mixing 1% lidocaine with 0.5% bupivacaine (1:1 ratio) when prolonged postoperative analgesia is desired 4

Procedural Steps

1. Position the patient with the hand supinated and fingers extended
2. Prepare the injection site with antiseptic solution
3. Use a 25-gauge needle attached to a 3 mL syringe 3
4. Insert the needle at the chosen site (palmar crease for transthecal approach or volar subcutaneous space for tumescent technique)
5. Aspirate before injection to ensure the needle is not intravascular
6. Inject slowly to minimize discomfort and tissue trauma 5, 3
7. Wait 5-10 minutes for complete anesthesia to develop 4
8. Test sensation with pinprick on both dorsal and volar surfaces before proceeding 5, 4

Critical Safety Considerations

Avoid Traditional Ring Blocks

• Traditional circumferential ring blocks requiring multiple injections are more painful and no more effective than single-injection techniques 5, 4
• The single-injection approach reduces procedure time (mean 113 seconds) and patient discomfort 4

Volume Limits

• Keep total volume to 2-3 mL for adult digits to avoid compartment syndrome 5, 4, 3
• Smaller volumes (1.5-2 mL) may be appropriate for the smaller pinky finger 5

Common Pitfalls to Avoid

• Do not inject directly into the nerve, as this can cause nerve injury; inject adjacent to or around the nerve 6
• Do not use excessive pressure during injection, which may indicate intraneural placement 3
• Ensure adequate wait time before testing anesthesia; premature testing may lead to unnecessary repeat injections 4

Expected Outcomes

• Complete loss of pinprick sensation on both dorsal and volar aspects of the digit within 5-10 minutes 5, 4
• Duration of anesthesia: 2-4 hours with plain lidocaine, 5-7 hours when epinephrine is added 7
• Success rate exceeds 94% when technique is performed correctly 4, 3
• Adverse events are rare when proper technique is used; no cases of digital necrosis reported in recent studies 5, 4, 7