Page 9 - CASA Bulletin of Anesthesiology 2019 Vol 6 No 5

Vol.6, No.5, 2019

Superior Trunk Block: A phrenic-sparing alternative surgical block

to the Interscalene block

David H Kim MD, Yi Lin MD PhD
Attending anesthesiologist, Hospital for Special Surgery, Cornell Medical College, New York, NY, USA

[The following article is a review summary of our latest
publication in Anesthesiology, Published on July 3, 2019 .
doi:10.1097/ALN.0000000000002841]

Highlight: David Kim, MD Yi Lin, MD
Superior trunk block is a surgical block
Superior trunk block was noninferior to interscalene block in regards to pain and patient sat-
isfaction
superior trunk block is associated with much less frequent hemidiaphragmatic paralysis

Review:
Interscalene block has been considered the gold standard in terms of anesthetic technique
for arthroscopic shoulder surgery(1,2,3) . It provides superior surgical anesthesia and profound
postoperative analgesia, expediting discharge and lowering opioid consumption(3) . It has been
used widely for decades and remains a crucial part of any opioid-sparing multimodal arma-
mentarium. However, its benefits are often at the expense of an unacceptably high incidence of
hemidiaphragmatic paralysis via inadvertent blockade of the phrenic nerve, thereby making the

use among patients with pulmonary disease less than ideal . As the technique has been shown to
be associated with almost complete 100% hemidiaphragmatic paralysis(4,5), serious pulmonary
complication and distress can result . This limitation has led to an increased interest in novel
block techniques to improve the brachial plexus block for shoulder surgeries .

The strong interest is evident in a surge of research literature for the last several years that
sought to find ways to provide sufficient anesthesia and analgesia to the shoulder while preserv-
ing the function of the phrenic nerve. Advances in fine-resolution ultrasonography have enabled
investigators to precisely visualize and selectively target nerves and structures of the brachial

plexus. Overall, strategies have revolved around focusing on either defined segments or specific
individual nerves along the brachial plexus, and reducing the local anesthetic concentration and
volume .

Brachial plexus blocks have been traditionally classified according to the anatomic landmark
associated with the level of the injection site . Interscalene blocks target the brachial plexus at the
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