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How To Do a Digital Nerve Block

By

Richard Pescatore

, DO, Delaware Division of Public Health

Last full review/revision Oct 2021| Content last modified Oct 2021
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A digital nerve block anesthetizes a finger.

Indications

  • Laceration or other surgically treated lesion of a finger*

  • Ring removal

A digital nerve block has advantages over local anesthetic infiltration; it typically causes less pain, provides better anesthesia, and does not distort wound edges, which is important because there is little extra space in the fingers.

* This includes fracture, dislocation, fingernail removal, infection.

Contraindications

Absolute contraindications

  • History of allergy to the anesthetic agent or delivery vehicle (choose a different anesthetic)

  • Absence of anatomic landmarks needed to guide needle insertion (eg, due to trauma)

Relative contraindications

* Therapeutic anticoagulation (eg, for pulmonary embolism) increases the risk of bleeding with nerve blocks, but this must be balanced against the increased risk of thrombosis (eg, stroke) if anticoagulation is reversed. Discuss any contemplated reversal with the clinician managing the patient's anticoagulation and then with the patient.

Complications

Most complications result from inaccurate needle placement.

Equipment

  • Nonsterile gloves

  • Barrier precautions as indicated (eg, face mask, safety glasses or face shield, cap and gown)

  • Antiseptic solution (eg, chlorhexidine, povidone-iodine, alcohol)

  • Injectable local anesthetic* such as lidocaine 2% with epinephrine† 1:100,000, or for longer- duration anesthesia, bupivacaine 0.5% with epinephrine† 1:200,000

  • Syringe (eg, 3 mL) and needle (eg, 25 or 27 gauge) for anesthetic injection

† Maximum dose of local anesthetics: Lidocaine without epinephrine, 5 mg/kg; lidocaine with epinephrine, 7 mg/kg; bupivacaine, 1.5 mg/kg. NOTE: A 1% solution (of any substance) represents 10 mg/mL (1 g/100 mL). Epinephrine causes vasoconstriction, which prolongs the anesthetic effect. Patients with cardiac disease should receive only limited amounts of epinephrine (maximum 3.5 mL of solution containing 1:100,000 epinephrine); alternatively, use local anesthetic without epinephrine.

Additional Considerations

Relevant Anatomy

  • Each finger is innervated by 4 nerves: bilateral dorsal and palmar digital.

  • The palmar digital nerves originate from the medial and ulnar nerves.

  • The dorsal digital nerves originate from the cutaneous branches of the ulnar and radial nerves that wrap around to innervate the dorsum of the hand.

  • Digital nerve blocks are traditionally placed in the web space adjacent to the metacarpal head, with one needle insertion on each side of the finger.

  • The middle 3 fingers can be anesthetized by blocking only the palmar digital nerves of those fingers.

  • The thumb and little finger are anesthetized by blocking both their palmar and dorsal digital nerves.

Positioning

  • Position the patient with the arm supported. The hand is supinated for volar injections and pronated and flat for dorsal injections (eg, ring block).

Step-by-Step Description of Procedure

  • Check sensation of the finger (palmar and dorsal surfaces).

  • Wear gloves and use appropriate barrier precautions.

  • Cleanse the site with antiseptic solution.

Bilateral dorsal injections (traditional ring block)

  • Place the hand and wrist prone (palm down).

  • On one side of the finger, insert the needle perpendicularly into the dorsal web space, adjacent to the medial aspect of the metacarpal head. Slowly inject about 1 mL of anesthetic to block the dorsal digital nerve. Then continue to advance the needle downward into the palmar space, while slowly injecting another 1.5 mL of anesthetic to block the palmar digital nerve. Take care not to penetrate the palmar aspect of the finger.

  • To complete the digital block, duplicate the needle insertion and injection on the other side of the finger.

Single volar injection

  • Place the hand and wrist supine (palm facing up).

  • Identify the digital-palmar crease (where the finger joins the palm). If necessary, have the patient flex the finger against resistance to make the crease more prominent.

  • Insert the needle vertically at the midpoint of the crease and advance the tip subcutaneously.

  • Aspirate to exclude intravascular placement, and then slowly inject about 3 mL of anesthetic.

  • Massage the injection area to spread the anesthesia.

  • If paresthesia occurs during needle insertion, withdraw the needle 1 to 2 mm before injecting.

  • Allow about 5 to 10 minutes for the anesthetic to take effect.

Aftercare

  • Ensure hemostasis at the injection site.

  • Instruct patient regarding anticipated time to anesthesia resolution.

Warnings and Common Errors

  • To minimize the risk of needle breakage, do not bend the needle, insert it to its full depth (ie, to the hub), or attempt to change direction of the needle while it is inserted.

  • To help prevent nerve injury or intraneural injection, instruct patients to report paresthesias or pain during the procedure.

  • To help prevent intravascular injections, aspirate before injecting.

Tricks and Tips

References

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