Digital Nerve Blocks
DIGITAL NERVE BLOCKS -- Dr. Hannah Crowley
Review of digit innervation: Cross-section of digit
Contraindications to digital nerve block:
-Vascular compromise to the digit
-Overlying infection/cellulitis
-Allergy to anesthetic agent
Choice of anesthetic agent:
-Lidocaine 1% or 2%: analgesia for 30-40mins
-Bupivacaine 0.25%: analgesia for several hours
A note on lidocaine with epinephrine: It was previously thought that using epinephrine for digital blocks was contraindicated due to the risk of vasoconstriction and vascular compromise. Studies have not found definitive evidence that lidocaine with epinephrine is contraindicated in digital nerve blocks, however, in patients with PVD or other risk factors for vascular compromise use of epinephrine should be avoided
Further reading on the topic of using epinephrine in digital nerve blocks:
Ilicki J. Safety of Epinephrine in Digital Nerve Blocks: A Literature Review. J Emerg Med. 2015 Nov;49(5):799-809. doi: 10.1016/j.jemermed.2015.05.038. Epub 2015 Aug 4. PMID: 26254284.
Prabhakar H, Rath S, Kalaivani M, Bhanderi N. Adrenaline with lidocaine for digital nerve blocks. Cochrane Database Syst Rev. 2015 Mar 19;2015(3):CD010645. doi: 10.1002/14651858.CD010645.pub2. PMID: 25790261; PMCID: PMC7173752.
Two Common Types of Digital Blocks:
Traditional (finger web-space) Block:
-Cleanse skin overlying the dorsal surface of base of digit
-Insert the needle perpendicular to the finger, just distal to the MCP joint and lateral to the bone
-Slowly advance the needle toward the palmar surface until you see tenting of the palmar skin. Inject while withdrawing the needle, about 1-1.5cc should be sufficient
-Repeat on the opposite side of digit
Transthecal (flexor tendon sheath) Block:
-This technique requires a single injection of anesthetic into the flexor tendon sheath. The anesthetic agent travels along the course of the sheath and causes analgesia of all four nerves.
-Palpate for the flexor tendon sheath at the palmar crease
-Clean overlying skin
-At a 45 degree angle, puncture the skin just distal to the palmar crease
-Once you have entered the sheath, inject 1-2cc of anesthetic agent. If you are correctly in the sheath the anesthetic should flow easily. If you encounter resistance, you are likely against the tendon. If this happens withdraw slightly to correctly position the needle within the sheath
References:
1. Baldor R, Mathes BM. Digital nerve block. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on November 11, 2021)
2. Ilicki J. Safety of Epinephrine in Digital Nerve Blocks: A Literature Review. J Emerg Med. 2015 Nov;49(5):799-809. doi: 10.1016/j.jemermed.2015.05.038. Epub 2015 Aug 4. PMID: 26254284.
3. Prabhakar H, Rath S, Kalaivani M, Bhanderi N. Adrenaline with lidocaine for digital nerve blocks. Cochrane Database Syst Rev. 2015 Mar 19;2015(3):CD010645. doi: 10.1002/14651858.CD010645.pub2. PMID: 25790261; PMCID: PMC7173752.