Anaesthesia - Digital nerve block
Indications
Digital pain (from injury or procedure)
Contraindications (absolute in bold)
Vascular compromise
Infection at the site of injection
Allergy to local anaesthetic agents
Alternatives
Local infiltration of local anaesthetic
Other regional nerve blocks
Informed consent
Verbal consent
Less complex non-emergency procedure with low risk of complications
Potential complications
Failure
Vasovagal reaction on insertion (syncope)
Allergic reaction
Pain at injection site
Haematoma (particularly if anticoagulated)
Nerve damage
Infection introduced by infiltration
Procedural hygiene
Standard precautions
Aseptic non-touch technique
PPE: non-sterile gloves
Area
Any clinical space
Staff
Procedural clinician
Equipment
5ml syringe and drawing up needle
23g needle for the adult injection
25g needle for paediatric injection
Positioning
Supine or sitting
Limb supported on a flat surface at working height for proceduralist
Injections made through the dorsal surface of the finger just distal to the MCP
Medication
2-5ml lignocaine 1-2% without adrenaline (duration 40 minutes)
2-5ml bupivacaine 0.25% (duration several hours)
1% means 10mg per ml (i.e. a 100% solution is 1000mg in 1ml)
For lignocaine 1%, the 3mg/kg maximum dose is approximately 20ml for a 70kg adult
For bupivacaine 0.25%, the 2mg/kg maximum dose is approximately 50ml for a 70kg adult
Sequence (dorsal approach)
Insert the needle on the dorsal aspect of the finger proximal to the finger web and distal to knuckle
Inject 0.5-1ml subdermally (blocking dorsal digital nerve)
Advance the needle along the bone until the palmer skin tents
Inject 0.5-1ml subdermally (blocking volar digital nerve)
Repeat on the opposite side of the finger
Massage the area for 30 seconds to enhance diffusion of anaesthetic
Wait five minutes for block to become effective
Test sharp sensation prior starting the surgical procedure
Post-procedure care
Inform patient the area may remain numb for up to six hours (bupivacaine)
Document the procedure and any immediate complications
Tips
Higher concentrations can reduce injection volume and discomfort
Cardiac monitoring is recommended for multiple infiltrations of anaesthetic (greater risk of toxicity)
Always confirm the dose of local anaesthetic is within safe limits
Discussion
Digital nerves can be blocked anywhere along their course including sites on the finger, in the webspace and between the metacarpals of the hand.
We have suggested the dorsal approach due to the advantage of thinner, less pain-sensitive skin than encountered on the volar approach. Our generally preferred site is just proximal to the finger webs, due to consistent nerve location and greater soft tissue to accommodate local anaesthetic. More proximal injections between the metacarpals may be required for some injuries.
Peer review
This guideline has been reviewed and approved by the following expert groups:
Emergency Care Institute
Please direct feedback for this procedure to ACI-ECIs@health.nsw.gov.au.
References
Australian and New Zealand College of Anaesthetists. Guidelines for the management of major regional analgesia. PS03. Melbourne, Vic: ANZCA; 2014. Available from: http://www.anzca.edu.au/documents/ps03-2014-guidelines-for-the-management-of-major-r.pdf
NSW Agency for Clinical Innovation. Local and regional anaesthesia. Sydney: ACI; 2019 Sep 2. Available from: https://aci.health.nsw.gov.au/networks/eci/clinical/clinical-resources/procedures/local
Roberts JR, Custalow CB, Thomsen TW. Roberts and Hedges' clinical procedures in emergency medicine and acute care. 7th ed. Philadelphia, PA: Elsevier; 2019.
Dunn RJ, Borland M, O'Brien D (eds.). The emergency medicine manual. Online ed. Tennyson, SA: Venom Publishing; 2019.
Australian medicine handbook online. Adelaide (SA): Australian Medicines Handbook; 2000. Bupivacaine. Australian Medicines Handbook. (updated 2020 Jan). Available from: https://amhonline.amh.net.au
Australian medicine handbook online. Adelaide (SA): Australian Medicines Handbook; 2000. Lidocaine (anaesthesia). Australian Medicines Handbook. (updated 2020 Jan). Available from: https://amhonline.amh.net.au
Baldor R, Mathes BM. Digital nerve block. In: UpToDate. Waltham (MA): UpToDate. 2020 Apr 10. Retrieved July 2019. Available from: https://www.uptodate.com/contents/digital-nerve-block
Knoop K, Trott A, Syverud S. Comparison of digital versus metacarpal blocks for repair of finger injuries. Ann Emerg Med. 1994;23(6):1296‐1300. doi:10.1016/s0196-0644(94)70355-8