Ultrasound guided supraclavicular brachial plexus block (BPB) has been extensively
studied and recommended as a sole anesthetic for upper extremity surgeries. The
supraclavicular BPB is often touted to be the 'spinal of the upper extremity' as it
produces anesthesia of the entire upper extremity except for the T2 dermatome.
However, based on clinical experience, such a claim is grossly unsubstantiated. This is
evident from the finding that supraclavicular BPB is associated with 2-36% inferior trunk
or ulnar nerve sparing. In addition, since the suprascapular nerve takes off more
proximally from the superior trunk and the supraclavicular BPB is performed distally at
the supraclavicular fossa, the effect of supraclavicular BPB on the suprascapular nerve,
which predominantly supply the shoulder and proximal humerus, is not known and has not
been objectively documented.
Nonetheless, supraclavicular BPB has been successfully used for shoulder surgery albeit
with a large local anesthetic (LA) volume (50-60 ml) or combined with interscalene BPB, a
hybrid BPB technique using 30-50 ml LA volume, for proximal humerus fracture surgeries.
But such high LA volume is invariably associated with potential complications in the high
risk population and therefore not used in contemporary clinical practice.
Since all major nerves supplying the upper extremity, including suprascapular nerve,
passes through the trunks of the brachial plexus, we proposed that by selectively
identifying and blocking the three trunks of the brachial plexus with small doses of
LA-selective trunk block (SeTB), it is feasible to produce anesthesia of the entire upper
extremity, i.e., from shoulder to hand. This is further confirmed from the results of our
research evaluating the efficacy of ultrasound-guided (USG) SeTB for surgical anesthesia
of the entire upper extremity and cadaver anatomic study evaluating the spread of the
injectate after a simulated SeTB. Although these are encouraging results, there is a
paucity of data on the sensorimotor blockade and incidence of hemidiaphragmatic palsy
comparing SeTB and supraclavicular BPB techniques which this study aims to evaluate. We
hypothesize that USG SeTB is superior to supraclavicular BPB in anesthetizing the entire
upper extremity from shoulder to hand.
