M A Y 2 0 1 6 • O U T PA T I E N TS U R G E R Y. N E T • 1 4 1
1. Place the ultrasound probe inferior to
the clavicle in a paramedian orienta-
tion. At this location you can identify
the axillary artery, vein and pectoralis
major and minor. If a rib is visible, it
will be the 2
nd
rib with the pleura
below.
2. Scan down the chest in a caudad
direction and count the ribs as you
go. Once you identify the 3
rd
rib,
rotate the probe 90 degrees and slide
it toward the lateral aspect of the
chest wall. At this point you'll be
able to identify pectoralis major and
minor, the pectoral branch of the
thoracoacromial artery between
them, the 3
rd
and 4
th
ribs, and the
pleura between them. This is the
optimal position for both blocks.
3. For PECs I, place 20 ml of local anes-
thetic between the pectoralis major and minor in the vicinity of the thoracoacromial artery.
4. For PECs II, simply place the needle between the anterior serratus and pectoralis minor,
inject 20 ml of local anesthetic and, on the way out, inject 10 cc of local anesthetic between
the pectoralis major and minor in the vicinity of the thoracoacromial artery. The injection
sequence is important, because injecting between the pectoralis minor and major first could
compress or distort the anatomy and make it harder to identify the anterior serratus and pec-
toralis major planes. — Mike MacKinnon, CRNA
• LANDMARKS The PEC I and PEC II blocks should be rel-
atively easy to master with practice.
EASY AND RELIABLE
How to Administer a Pectoral Nerves Block
• COVERAGE The PEC I (left) covers the median and lateral pec-
toral nerves, which lie between the pectoralis major and pectoralis
minor muscles. The PEC II covers those plus the axillary area.
Mike
MacKinnon,
CRNA
