Digital nerve block

Disclaimer These guidelines have been produced to guide clinical decision making for the medical, nursing and allied health staff of Perth Children’s Hospital. They are not strict protocols, and they do not replace the judgement of a senior clinician. Clinical common-sense should be applied at all times. These clinical guidelines should never be relied on as a substitute for proper assessment with respect to the particular circumstances of each case and the needs of each patient. Clinicians should also consider the local skill level available and their local area policies before following any guideline.  Read the full PCH Emergency Department disclaimer.

Aim

To guide Emergency Department (ED) staff in the use of digital nerve block. 

Background

A digital nerve block is used to anaesthetise a finger, thumb or toe for a procedure. It requires injection of local anaesthetic to interrupt nerve signals travelling back from the digit.

Pre-Procedure

A digital nerve block is used to anaesthetise a finger, thumb or toe for a procedure. It requires injection of local anaesthetic to interrupt nerve signals travelling back from the digit.

Indications¹

• Finger or toe injuries requiring treatment that will take less than 30-45 minutes e.g. finger lacerations requiring suturing
• Manipulation of phalangeal fractures or interphalangeal joint dislocations
• Nail bed injuries requiring exploration or repair
• Drainage of paronychia (infection of the nail fold or pulp).

Requirements

• The patient needs to be able to cooperate with injections and hold still for the procedure intended.
• Formal consent is not required but the procedure should be clearly documented.
• A clear explanation of the procedure needs to be provided to the patient.
• Risks need to be explained:
  • Pain as the injection is made.
  • Digital nerve block might not work.
  • Bruising and bleeding at the site of injection
• Ensure the patient is in the appropriate treatment area

Preparation

Equipment and dosing

• Sterile gloves and dressing pack with antiseptic (chlorhexidine 2% or similar).
• 5mL syringe filled with lidocaine (lignocaine) 1% (50mg/5mL) or lidocaine (lignocaine) 2% (100mg/5mL) without adrenaline (epinephrine).
  • Maximum dose of lidocaine (lignocaine) is 3 mg/kg without adrenaline (epinephrine).^3,4

OR

• 5mL syringe filled with lidocaine (lignocaine) 1% with adrenaline (epinephrine) 1:100,000.
  • Maximum dose of lidocaine (lignocaine) is 7 mg/kg (not to exceed adult maximum of 500mg) with adrenaline (epinephrine).3, 5

• Warm lidocaine (lignocaine) to body temperature (i.e. in your hand) to reduce discomfort.
• 25G needle (orange) for the injection.
• Consider topical local anaesthetic e.g. lidocaine (lignocaine) with prilocaine (EMLA®) application over injection site.
• Consider nitrous oxide for sedation whilst injections are occurring. Refer to Nitrous Oxide/Oxygen (50:50): Self Demand - Medication Management Guideline (internal WA Health only).

Procedure

Positioning and technique

• Position the patient lying on a bed with their hand or foot appropriately draped and prepare with aseptic technique.
• Injections will be through the dorsal surface of the digit just distal to the metacarpophalangeal joint/metatarsophalangeal joint.
  • Insert the needle on the side of the digit into the dermis.
  • Advance the needle nearly to the palmar/plantar surface of the digit.
  • Aspirate the needle to confirm that it is not in a blood vessel.
  • Inject approximately 1mL of anaesthetic solution (enough to make the skin slightly bulge) as the needle is slowly withdrawn.¹
  • Repeat on the other side of the digit.
• It is then important to wait several minutes (up to 10 minutes) for the block to become effective. If the digit still has some sensation, it is possible to repeat the injections to improve the effect (and wait for another 5-10 minutes).

References

1. King C, and Henretic F (2008) Textbook of pediatric emergency procedures. Ch 35. Pg 439-468 Philadelphia: Lippincott Williams and Wilkins.
2. Royal Children’s Hospital Melbourne :Lidocaine (lignocaine) | Paediatric Injectable Guidelines Online (health.wa.gov.au). Update 2020. Cited 11 November 2021. Available from: Lidocaine (lignocaine) | Paediatric Injectable Guidelines Online (health.wa.gov.au)
3. Australian Medicines Handbook [Internet]. Adelaide: AMH; c2022. Lidocaine. Available from: Lidocaine (anaesthesia) - Australian Medicines Handbook (health.wa.gov.au
4. Lidocaine (local and regional anaesthetic) and (systemic): Drug information . in: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on January 19, 2021.)
5. Lidocaine and epinephrine: Drug information. in: UpToDate, Post TW (Ed), UpToDate, Waltham, MA. (Accessed on January 19, 2021.)

Endorsed by:	Drugs and Therapeutics Committee	Date:	Feb 2022
		Review date:	Feb 2024

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