What is the procedure for a digital nerve block?

From the Guidelines

A digital block is a local anesthesia technique used to numb fingers or toes for minor surgical procedures or pain relief, and it should be performed by injecting 1-2 mL of anesthetic, typically 1% lidocaine without epinephrine, at the base of the digit on both sides, after cleaning the area with an antiseptic solution. To perform a digital block, first clean the base of the digit with an antiseptic solution like chlorhexidine or povidone-iodine.

• Use a 27-30 gauge needle to inject the anesthetic.
• For fingers, inject at the web spaces on both sides of the digit at the metacarpophalangeal joint level, targeting the digital nerves.
• For toes, inject at the base on both sides.
• Wait 5-10 minutes for complete anesthesia before beginning any procedure. The anesthetic blocks the digital nerves that run along both sides of the digit, preventing pain signals from traveling to the brain.
• Lidocaine without epinephrine is preferred because vasoconstriction in end arteries could potentially compromise circulation, as noted in various studies 1.
• The effect typically lasts 1-2 hours, providing sufficient time for most minor procedures.
• Always aspirate before injecting to avoid intravascular injection, and be aware that patients may experience a burning sensation during injection. Regional anesthesia techniques, including digital blocks, are effective in both adults and children in site-specific surgery, with strong recommendation and high-quality evidence 1.
• The use of perineural/local analgesia techniques is indicated in case of major interventions characterized by moderate-to-severe pain, and the most frequently used peripheral nerves block is the use of the rectus sheath block and the transversus abdominis plane (TAP) block 1.
• Local anesthetics would directly block transmission of pain from nociceptive afferents from the wound surface, and local anesthetic may also inhibit local inflammatory response to injury 1.

From the FDA Drug Label

LIDOCAINE HYDROCHLORIDE INJECTION, FOR INFILTRATION AND NERVE BLOCK, SHOULD BE EMPLOYED ONLY BY CLINICIANS WHO ARE WELL VERSED IN DIAGNOSIS AND MANAGEMENT OF DOSE-RELATED TOXICITY AND OTHER ACUTE EMERGENCIES THAT MIGHT ARISE FROM THE BLOCK TO BE EMPLOYED To avoid intravascular injection, aspiration should be performed before the local anesthetic solution is injected The needle must be repositioned until no return of blood can be elicited by aspiration.

A digital block is a type of local anesthesia that involves injecting a local anesthetic, such as lidocaine, around the nerves that supply the digits. The key steps to perform a digital block include:

• Preparation: Ensure the immediate availability of oxygen, resuscitative drugs, cardiopulmonary equipment, and personnel needed for proper management of toxic reactions and related emergencies 2.
• Aspiration: Perform aspiration before injecting the local anesthetic solution to avoid intravascular injection 2.
• Injection: Inject the local anesthetic solution around the nerves that supply the digits.
• Monitoring: Monitor the patient for signs of methemoglobinemia, such as cyanotic skin discoloration and/or abnormal coloration of the blood 2.

From the Research

Digital Block Procedure

A digital block is a procedure used to anesthetize the fingers or toes, and it involves injecting an anesthetic agent into the digital nerves. The principal nerves in the wrist and the digital nerves in the hand or fingers are anatomically superficial, making them easily accessible for percutaneous injection of anesthetic agents such as lidocaine, bupivacaine, and mepivacaine 3.

Anesthetic Agents

The choice of anesthetic agent is crucial in digital block procedures. Studies have compared the efficacy of different anesthetic agents, including lidocaine, bupivacaine, and a combination of lidocaine and bupivacaine. One study found that bupivacaine 0.25% digital block induces anesthesia in the same period of time and with equivalent pain of injection as a 1:1 lidocaine 1%/bupivacaine 0.25% combination 4.

Use of Epinephrine

The use of epinephrine in digital nerve blocks has been a topic of debate. Some studies have suggested that epinephrine may increase the risk of digital necrosis, while others have found no evidence to support this claim. A literature review found that epinephrine 1:100,000-200,000 (5-10 μg/mL) is safe to use in digital nerve blocks in healthy patients, and that physiological studies show epinephrine-induced vasoconstriction to be transient 5. Another study found that the addition of epinephrine to the anesthetic solution reduces the need for the use of tourniquets and large volumes of anesthetic, and provides better and longer pain control during digital procedures 6.

Key Considerations

When performing a digital block, it is essential to consider the following key points:

• Careful selection of the anesthetic agent and type of nerve block can provide safe and effective anesthesia for many surgical procedures of the hands and fingers 3.
• Proper injection technique and adequate selection of patients are mandatory to minimize complications 6.
• The use of epinephrine in digital nerve blocks may be safe in healthy patients, but caution should be exercised in patients with risk factors for poor peripheral circulation 5.
• The advantages of adding epinephrine to the anesthetic solution should be weighed against the potential risks of the procedure 7.