Median 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 PCH ED staff in the use of median nerve block.

Definition

A median nerve block uses local anaesthetic to block the nerve at the wrist, allowing procedures on the radial side of the palm, palmar surface and tip of the thumb, index and middle finger and (variably) the ring finger.

Median nerve block local anaesthetic areas

Pre-procedure

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

Indications

  • Suitable for use in injuries requiring procedures on the radial side of palm, palmar surface and tip of the thumb, index, middle and ring fingers where treatment of duration less than 30-45 minutes such as:
    • finger or hand lacerations requiring suturing
    • removal of foreign body from palm or medial fingertips
    • part of a hand block (with radial and ulnar nerve blocks)
  • Not suitable for joint or fracture manipulation without doing a radial nerve block as well

Preparation

Equipment

  • Dressing pack with antiseptic (chlorhexidine or similar)
  • 5mL syringe filled with lignocaine 1% or 2% (with or without adrenaline)
    • Maximum dose of lignocaine is 3 mg/kg
  • Warm lignocaine to body temperature (i.e. in your hand) to reduce discomfort
  • 25 gauge needle (orange) for the injection
  • Consider EMLA® application over injection site
  • Consider nitrous oxide for sedation whilst injections are occurring.

Procedure

Positioning and technique

  • Position patient with palm held upwards and slightly flexed
  • Drape wrist appropriately and prepare with aseptic technique
  • Inject site 1-2 cm proximal to the proximal wrist crease with the needle vertical just radial to the palmaris longus tendon or the midline (ulnar side of flexor carpi radialis) if the tendon is absent (palmaris longus is absent in up to 14% of the population)
  • Advance the needle until there is no resistance
  • Aspirate the needle to ensure that it is not in a blood vessel
  • If parasthesia is felt do not inject (this indicates that the needle lies within the nerve and will cause damage)
  • Inject 2-3 ml of lignocaine slowly (should be easy to inject if in the right place)
  • Allow up to 10 minutes for the block to become effective. If the area still has some sensation, a repeat injection can improve the effect (after another 5-10 minutes).

Bibliography

  1. Fleisher GR, Ludwig S. Textbook of Pediatric Emergency Medicine. 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2010.
  2. Paediatric Emergency and Critical Care Procedures Editor  R Dieckmann Mosby

Endorsed by:  Director, Emergency Department   Date:  Apr 2018


 Review date:   Apr 2021


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