Nerve Block: Median

Revision as of 03:17, 9 April 2017 by TJYE (talk | contribs) (Procedure)

Background

  • Useful for lacerations across multiple fingers/palm instead of multiple digit blocks
  • Useful for exploration of flexor tendons of digits 1-3
  • Ultrasound guidance significantly increases the success rate of this block [1]
The yellow area indicates the area of the hand innervated by the median nerve

Indications

  • Trauma or need to perform painful procedure on area innervated by median nerve

Contraindications

  • Infection overlying injection site
  • Previous allergic reaction to local anesthesic used
  • Distortion of anatomic landmarks

Equipment Needed

  • Topical anesthesia (LET, EMLA)
  • local anesthesia
    • Lidocaine 1% (lasts 30-60 minutes or longer if given with epinephrine, rapid onset)
    • Mepivacaine 3% (lasts 45-90 minutes, slower onset)
    • Bupivacaine 0.5% (lasts 2-4 hours, slowest in onset)
  • 18G needle to draw up anesthetic
  • 25-30G needle to inject
  • 10 cc syringe
  • Gauze pads

Procedure

Median nerve lies between palmaris longus and flexor carpi radialis.
  • Time out, confirm correct patient and laterality
  • Apply topical anesthesia if needed
  • Draw up 5-10 mL of anesthetic into syringe
  • Before any nerve block, perform neurovascular exam (often includes 2 patient discrimination with paperclip)

Wrist Block

  • Median nerve is within the carpal tunnel
  • Between palmaris longus and flexor carpi radialis
  • Insert needle perpendicular between tendons, 2-3 cm proximal to the distal crease of the wrist
  • Aspirate; if no blood inject a few mL's of anesthetic slowly
  • Test sensation to pain distal to block

Elbow Block

Upper Extremity Nerves
  • Cleanse the skin overlying the antecubital fossa with chosen antiseptic
  • Create a sterile field using sterile drape
  • In a sterile fashion, apply a small wheel of local anesthetic to the area immediately proximal to the antecubital fossa
  • Palpate the brachial artery to be aware of its path
    • The median nerve should be approximately 1 cm medial to the brachial artery at this point
  • Insert the needle approximately 1-2 cm proximal to the flexor crease and advance with negative pressure applied to the syringe
  • At 1-2 cm deep, aspirate prior to injection to rule out intravascular placement
  • Inject 5-10 mL of local anesthetic

Ultrasound Guided Block

  • Place a linear probe on the volar aspect of the midforearm
  • The median nerve takes the appearnce of a "chocolate chip cookie" in the axial orientation and lies between the flexor digitorum profundus and supeficialis
  • Clean and prep the patient's arm under sterile conditions, and insert a 25 g needle in the long axis under ultrasound guidance next to the nerve
  • Aspirate to prevent inadvertent intravascular injection
  • Inject 5 mL of local anesthetic so that it basks the nerve

Complications

  • Bleeding
  • Infection
  • Pain
  • Needle fracture
  • Neurapraxia

See Also

External Links

References

  1. Liebmann O, Price D, et al. [Feasibility of Forearm Ultrasonography-Guided Nerve Blocks of the Radial, Ulnar, and Median Nerves for Hand Procedures in the Emergency Department]. Ann Emerg Med 2006; 48(5):558-62.