Coracoid/Infraclavicular Brachial Plexus Block

Indications
Surgery of the upper extremities — distal to the shoulder,
e.g., elbow, forearm, hand

Set-Up

• Betadine/alcohol pads
• Ruler and marker
• Nerve stimulator – Braun “stimuplex” system with
  4 inch/10 cm 22G Needle
• Two 30 ml. syringes with local anesthetic (1.5%
  mepivacaine + epinephrine (1:200,000) + HCO3
  - (0.1 mEq/cc)
• For longer acting blocks, 10 ml of 0.75% bupivacaine + epinephrine (1:200,000) may be added.

Anatomy (Fig. 3-1)

• The coracoid process is a bony prominence inferior
  to the clavicle and medial to the humeral head.
• The brachial plexus along with the subclavian vessels
  travel caudad and medial to the coracoid process.
  

Figure 3-1 Illustration by Beth Halasz Western Reserve Medical Art

Technique

• Place the patient supine, placing the hand so that it
  is easily seen while performing the block. Identify
  the coracoid process. Skin entry point is 2 cm medial
  and 2-3 cm caudad to the coracoid process.
  Mark the most prominent (anterior) part of the coracoid
  process and draw a line 2 cm medial. Then
  draw a perpendicular line 3 cm caudad and mark
  2.5 cm. On thin patients, insert needle at 2 cm and
  for heavier patients insert needle at 2.5-3 cm.
• Set the nerve stimulator at 1.5 Amp, 2 Hz. Insert a
  4 inch stimuplex (22G) needle aiming directly posterior.
  The first twitch is usually seen in the pectoralis
  muscle, secondary to direct nerve stimulation.
  Keep going until you find the neurovascular bundle,
  which is usually 4 to 6 cm from the skin. The next
  twitch obtained is often biceps flexion due to stimulation
  of nerve fibers leading to musculocutaneous
  nerve. Do not inject local anesthetic on this response
  or on a wrist twitch. Instead, search for a finger
  or thumb twitch.
• Reposition needle through an arc of 20° caudad, i.e.,
  redirect slightly inferiorly.
• Do not aim needle medially. If necessary, re-orient
  the needle laterally.
• Once the desired motor response is obtained, maximize
  the twitch by manipulating the needle with
  small anterior-posterior movements while reducing
  the current to < 0.5 mAmps. Puncture of the brachial
  artery and vein is possible but usually inconsequential
  with the 22G needle. Puncture of the
  artery with a 17G needle (while placing a perineural
  catheter) may necessitate changing the planned
  anesthetic.
• Incrementally inject 45 to 55 ml of local anesthetic
  with frequent aspiration. Injection should not be
  very difficult nor should it be very painful as these
  may be signs of an injection directly into a nerve
  root.

Limitations

• The proximity to the vessels of the arm make many
  practitioners nervous about catheter placement with
  a large needle.

Complications

• Pneumothorax
• Intravascular Injection

Pearls

• 	Figure 3-2

  Onset may be somewhat slower than axillary or
  interscalene blocks
• If the plan is for block + general, the biceps twitch
  may be acceptable.
• Consider blocking the intercostobrachial nerve with
  subcutaneous infiltration in axilla (e.g., 5 cc of 2%
  lidocaine or 0.5% bupivacaine).

References

1. Koscielniak-Nielsen ZJ, Rotboll Nielsen P, Risby
   Mortensen C, “A comparison of coracoid and axillary
   approaches to the brachial plexus,” Acta anaesthesiol
   Scand. 44(3):274-9 (2000).
2. Wilson JL, Brown DL, Wong GY, Ehman RL, Cahill DR,
   “Infraclavicular brachial plexus block: parasagittal
   anatomy important to the coracoid technique,” Anesth
   Analg 87(4):870-3 (1998).
3. Desroches J, “The infraclavicular brachial plexus block
   by the coracoid approach is clinically effective: an observational
   study of 150 patients,” Can J. anaesth.

These technique descriptions are presented for educational purposes and are not intended to substitute for actual hands-on training.