How To Do a Radial Nerve Block

Laceration or other surgically treated lesion of the dorsum of the radial (lateral) half of the hand, including the thumb through the radial half of the ring finger, excluding the fingertips from the index finger through the radial half of the ring finger*

Ring removal

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)

Infection in the path of needle insertion: Use procedural sedation How To Do Procedural Sedation and Analgesia Procedural sedation and analgesia (PSA) is the administration of a short-acting sedative-hypnotic or dissociative agent, with or without an analgesic, for patients undergoing anxiety-provoking... read more or other anesthesia.

Coagulopathy*: When feasible, correct prior to procedure, or use a different means of analgesia.

Adverse reaction to the anesthetic or delivery vehicle Local anesthesia for laceration treatment (eg, allergic reaction to the anesthetic [rare] or to methylparaben [a preservative])

Toxicity due to anesthetic overdose (eg, seizure, cardiac arrhythmias) or sympathomimetic effects due to epinephrine (if using an anesthetic-epinephrine mixture)

Intravascular injection of anesthetic or epinephrine

Hematoma

Neuritis

Spread of infection, by passing the needle through an infected area

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, 10 mL) and needle (eg, 25 or 27 gauge, 3.5 cm long) for anesthetic injection

For ultrasonography: Ultrasound machine with high-frequency (eg, 7.5 MHz or higher) linear array probe (transducer); probe cover (eg, transparent sterile dressing, single-use probe cover); sterile, water-based lubricant, single-use packet (preferred over multi-use bottle of ultrasound gel)

Document any preexisting nerve deficit before doing a nerve block.

Stop the nerve block procedure if you are unsure where the needle is or if the patient is uncooperative. Consider sedation How To Do Procedural Sedation and Analgesia Procedural sedation and analgesia (PSA) is the administration of a short-acting sedative-hypnotic or dissociative agent, with or without an analgesic, for patients undergoing anxiety-provoking... read more for patients who are unable to cooperate or remain still.

The radial nerve lies along the radial aspect of the wrist, just lateral (radial) to the radial artery at the proximal wrist crease.

The dorsal cutaneous branches of the nerve wrap around the radius to innervate the dorsum of the radial side of the hand.

Position the patient with the arm resting with the palm facing up.

Check sensation and motor function of the radial nerve.

Wear gloves and use appropriate barrier precautions.

Palpate the radial artery at the radial styloid.

Needle-entry site: The needle will be inserted just lateral to the radial artery at the proximal wrist crease.

Cleanse the site with antiseptic solution.

Place a skin wheal of anesthetic, if one is being used, at the needle-entry site.

Insert the needle and advance it equal to the depth of the artery.

If paresthesia occurs during insertion, withdraw the needle 1 to 2 mm, aspirate to exclude intravascular placement, and then slowly (ie, over 30 to 60 seconds) inject about 2 mL of anesthetic.

If paresthesia does not occur, aspirate and then slowly inject about 2 to 5 mL of anesthetic.

Next, anesthetize the dorsal branches of the radial nerve: Withdraw and reposition the needle. Then inject another 5 mL of anesthetic subcutaneously from the initial insertion site to the dorsal midline of the wrist.

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

Ensure hemostasis at the injection site.

Instruct patient regarding anticipated time to anesthesia resolution.

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.

If using ultrasound, always maintain ultrasound visualization of the needle tip during insertion.

The distribution of the radial nerve is less predictable than the distribution of other nerves of the hand and wrist, thus a generous amount of anesthesia may be needed if ultrasound guidance is not used.

Minimize the pain of injection Local anesthesia for laceration treatment by injecting slowly (eg, 30 to 60 seconds), warming the anesthetic solution to body temperature, and buffering the anesthetic.