Which one of the following statements regarding approaches to the
blocking of the
brachial plexus is TRUE?
a) The axillary approach alone is sufficient for all aspects of awake
hand surgery
b) The interscalene approach blocks the plexus at the level of the
trunks
c) The vertical infraclavicular approach has the highest rate of
pneumothorax
d) An advantage of the supraclavicular approach is, being more
distal, phrenic nerve
block is not a complication
e) The subclavian perivascular approach relies on the plexus being
immediately
posterior to the subclavian artery as it crosses the first rib in between the scalenus
anterior and medius
Answer: e
Explanation
The axillary approach to the brachial plexus is attractive because
of the relative ease of
the technique and low complication rate, but has some significant disadvantages. It will
often spare the intercostobrachial and musculocutaneous nerves
thus tourniquet pain in
awake patients can be a problem if not addressed separately. The
single-shot technique
can also spare the radial nerve, again rendering it unsuitable for
complete anaesthesia for
hand surgery. These problems can be overcome with
ultrasound-guided targeted nerve
blocks at the same level. The interscalene approach blocks the
plexus at the level of the
roots and is likely to miss C8 and T1 giving rise to ulnar
sparing. It is therefore excellent
for shoulder surgery but should not be used as sole anaesthesia
for hand surgery. The
supraclavicular approach has the highest rate of pneumothorax (5%
in one series) but
when ultrasound guided it reliably blocks the whole of the
brachial plexus as the hourglass
nature of the plexus means that the trunks and proximal divisions
are closely
related here. It is sometimes referred to as the ‘spinal of the arm’. Back-tracking of the
local anaesthetic means that phrenic nerve block is still
encountered. The subclavian
perivascular approach is a landmark variant of the supraclavicular
block.
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