Supraclavicular and Interscalene Blocks

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Supraclavicular and Interscalene Blocks
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Interscalene Anatomy
SCM
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Brachial Plexus Sheath

• A sheath surrounds the brachial plexus, from the
  transverse processes all the way down into the
  axilla.

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Relations

• Brachial plexus is contained within a fascial
  sheath.
• Subclavian artery lies medial to plexus as they
  cross the 1st rib together.
• Note location of phrenic nerve and vertebral
  artery.

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Note that either lung or rib may be visualized
with US under the plexus.
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Typical Areas of Block
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Classic Interscalene Technique (1)

• The needle is placed in the groove perpendicular
  to all planes, with a slight caudal angulation.
• The classic entry point is at the level of C6,
  identified by the level of the cricoid cartilage,
  or where the EJ crosses the SCM.

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Supraclavicular BlockStandard Technique

• The goal of this technique is to inject the
  plexus near the 1st rib, where the roots have
  formed into trunks.
• The classic technique involved walking across the
  1st rib to find the plexus. This was associated
  with a 1-5 incidence of pneumothorax.
• Many authors have reported variations in
  technique, to try to reduce the pneumothorax risk.

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Issues With Standard Techniques
Body Size
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Issues With Standard Technique

• Phrenic Nerve Stimulation

If you get hiccuping, you are in front of the
anterior scalene. Move your needle one groove
further back.
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Issues With Standard Technique

• Posterior Muscle Contraction.

Posterior muscle contraction are from nerve that
have exited the sheath, and lie behind The middle
scalene. Move your needle one groove forward.
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Issues With Standard Technique

• Phrenic Nerve Dysfunction

This occurs in 100 of successful interscalene
blocks, because we have anesthetized the roots
that form the phrenic nerve. Its incidence is
lower and variable in supraclavicular blocks
depends on volume of local used.
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Injection Outside Sheath
Issues With Standard Technique
It is possible to get a good twitch and be
superficial to the sheath. Injection at this
location May result in block of the superficial
cervical plexus.
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Supraclavicular Ultrasound Imaging

• Positioning

Place roll under operative shoulder to allow
better access with needle. Keep needle,
transducer and monitor lined up.
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Supraclavicular Imaging

• Start parallel and adjacent to clavicle.
• May have to rotate probe slightly to get a good
  cross section.

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Lateral
Medial
Here is a nice example of the brachial plexus to
the left of the subclavian artery.
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Look for subclavian artery, with plexus sheath
on lateral aspect.
Lateral
Medial
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Medial
Lateral
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Interscalene Imaging

• Scan up from supraclavicular position.

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Moving the probe cephalad.
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Look for brachial plexus bundle between scalene
muscles.
Posterior
Anterior
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Posterior
Anterior
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Supraclavicular Approach

• Use in-plane approach only so position of
  needle relative to lung is always known.

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Lateral
Medial
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Interscalene Approach
Either in plane or out of plane approaches can be
used.
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Posterior
Anterior
Another example. Try to identify the anatomy.
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The brachial plexus is nicely delineated.
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Same patient with inplane approach injection
from the left side of the screen. The needle is
not visualized, but local anesthetic can be seen
entering the sheath.
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Local anesthetic
Same patient needle now imaged. Local
anesthetic can be seen pooling around the plexus.
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ScenarioShoulder Surgery

• Interscalene vs supraclavicular blocks
• GA by LMA or ETT.

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Sensory Innervation for Shoulder Surgery
Brachial plexus skin innervation.
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Sensory Innervation for Shoulder Surgery
Cervical plexus skin innervation.
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Sensory Innervation for Shoulder Surgery
T2-3 skin innervation. Only occasionally required
for shoulder surgery.
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Pros and Cons
IS one injection gets full coverage, but with
phrenic nerve dysfunction. SC doesnt get skin,
but can avoid or reduce phrenic nerve dysfunction.
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• In elderly patients, patients with COPD, or
  sleep apnea, I try to reduce the risk of phrenic
  nerve dysfunction by using supraclavicular
  approach.
• To anesthetize the skin, you can block the
  supraclavicular branches of the cervical plexus
  with a subcutaneous injection above the clavicle,
  starting at the needle entry site from the
  supraclavicular block.