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Although most upper extremity regional anesthesia is accomplished by
means of various approaches to the brachial plexus, there are occasions when
individual terminal nerves or their branches are blocked selectively. There
are generally three instances in which the anesthesiologist desires to
perform these selective nerve blocks. First, some surgical sites are
partially innervated by sensory nerves that are not part of the brachial
plexus or not consistently anesthetized with plexus blocks. This chapter
describes how and when to anesthetize the most common of these nerves—the
supraclavicular, the suprascapular, and the intercostobrachial. The second
indication is when blocking the entire brachial plexus block is not
necessary for the planned procedure. In this case, selective upper extremity
cutaneous anesthesia or analgesia may involve blocking terminal nerves
(radial, median, or ulnar nerves) or their branches (lateral and medial
antebrachial cutaneous nerves) distally at the elbow. A final and
controversial indication for selective upper extremity nerve blocks is their
use as a supplement to an incomplete brachial plexus block.
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This chapter discusses individual nerve blocks as a means of furthering
the reader's understanding of the indications and contraindications for
selective upper extremity regional anesthesia. When considering the
application of these various blocks, the reader is reminded that innervation
of the upper extremity is often variable and overlapping.1
Therefore, when faced with the choice of performing a single nerve block
versus blocking several adjacent nerves, it is advisable to err on the side
of multiple blocks, particularly in those adjacent cutaneous areas that
represent potential crossover innervation (Figures 31–1 and 31–2). The relevant anatomy will be covered with specific nerve block
description.
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Local Anesthetic & Adjuvant Selection
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Local anesthetics for individual upper extremity nerve blocks are
selected for their desired duration of anesthesia and/or analgesia. If
intermediate-acting local anesthetics are selected (lidocaine or
mepivacaine), duration can be increased with either adjuvant epinephrine
(2.5 mcg/mL) or clonidine (0.5 mcg/kg). Neither adjuvant significantly
increases duration when a long-acting local anesthetic such as bupivacaine or
ropivacaine is chosen.1
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The supraclavicular nerve provides sensory innervation to the “cape”
of the shoulder (Figure 31–3). Commonly anesthetized as a
component of cervical plexus block for carotid surgery, the supraclavicular
nerve may also require blockade for surgery involving the shoulder or
supraclavicular area. Local anesthetic spread in an interscalene approach to
brachial plexus block is often adequate to block the supraclavicular nerve,
but the nerve is frequently not anesthetized with a ...