Median

by | Aug 22, 2021

Indications

  • Hand laceration or injury

Contraindications

  • Infection overlying injection site
  • Allergy to local anesthetic
  • Vascular injury/injection: blocking proximal to elbow the median nerve runs with the brachial artery, ensure a negative aspiration prior to injection

Equipment

  • 5cc of local anesthetic of choice
  • 25-27G needle
  • Saline Flush
  • Cleansing solution
  • Ultrasound with high-frequency linear transducer
  • Ultrasound transducer sterile cover

Prepration

Position

Position patient supine with arm abducted to expose the volar forearm.

Ultrasound

Approach #1 (Elbow)

  1. Place the transducer on the radial aspect of the upper arm 2-3cm proximal to the elbow crease.
  2. Identify the brachial artery, the median nerve is just radial to the artery.
  3. Insert the needle in-plane from the radial aspect until the needle tip is adjacent to the nerve.
  4. After negative aspiration, hydrodissect 1-2 mLs of anesthetic to confirm placement, then inject anesthetic until the nerve is surrounded.

Approach #2 (Wrist)

  1. Place the transducer in transverse orientation over the midpoint of the forearm.

  1. The hyperechoic structure found in the fascial plane between the flexor digitorum superficialis and flexor digitorum profundus muscles is the median nerve.
  2. Insert the needle in-plane until the needle tip is adjacent to the nerve.
  3. Hydrodissect 1-2 mLs of anesthetic to confirm placement, then inject anesthetic until the nerve is surrounded.

Examples

In-plane median nerve block, with needle seen entering from screen right (ulnar aspect), with anesthetic deposited deep to median nerve (*). the radial artery can be seen pulsating superficial to and screen left of (radial to) the nerve.

Source

  1. The POCUS Atlas