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Anesthesiology. 2019 Aug 23. doi: 10.1097/ALN.0000000000002919. [Epub ahead of print]

Superior Trunk Block Provides Noninferior Analgesia Compared with Interscalene Brachial Plexus Block in Arthroscopic Shoulder Surgery.

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From the Department of Anesthesiology and Pain Medicine (R.A.K., J.S.J., J.H.L., S.J.C., M.S.G., T.S.H., J.S.K.) the Department of Orthopedics (J.C.Y.), Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea the Department of Anesthesia, Toronto Western Hospital, Toronto, Canada (K.J.C.).



Interscalene nerve block is commonly used for shoulder surgery for anesthesia and postoperative analgesiaUnfortunately, interscalene blocks commonly result in hemidiaphragmatic paralysis WHAT THIS ARTICLE TELLS US THAT IS NEW: When interscalene block was compared with superior trunk block, less frequent hemidiaphragmatic paralysis was seen in the superior trunk block groupSuperior trunk block was noninferior to interscalene block in terms of pain scores for up to 24 h postoperatively, and superior trunk block patients were no less satisfied BACKGROUND:: Interscalene brachial plexus block of the C5-C6 roots provides highly effective postoperative analgesia after shoulder surgery but usually results in hemidiaphragmatic paresis. Injection around the superior trunk of the brachial plexus is an alternative technique that may reduce this risk. The authors hypothesized that the superior trunk block would provide noninferior postoperative analgesia compared with the interscalene block and reduce hemidiaphragmatic paresis.


Eighty patients undergoing arthroscopic shoulder surgery were randomized to receive a preoperative injection of 15 ml of 0.5% ropivacaine and 5 μg · ml epinephrine around either (1) the C5-C6 nerve roots (interscalene block group) or (2) the superior trunk (superior trunk block group). The primary outcome was pain intensity 24 h after surgery measured on an 11-point numerical rating score; the prespecified noninferiority limit was 1. Diaphragmatic function was assessed using both ultrasonographic measurement of excursion and incentive spirometry by a blinded investigator before and 30 min after block completion.


Seventy-eight patients completed the study. The pain score 24 h postoperatively (means ± SDs) was 1.4 ± 1.0 versus 1.2 ± 1.0 in the superior trunk block (n = 38) and interscalene block (n = 40) groups, respectively. The mean difference in pain scores was 0.1 (95% CI, -0.3 to 0.6), and the upper limit of the 95% CI was lower than the prespecified noninferiority limit. Analgesic requirements and all other pain measurements were similar between groups. Hemidiaphragmatic paresis was observed in 97.5% of the interscalene block group versus 76.3% of the superior trunk block group (P = 0.006); paresis was complete in 72.5% versus 5.3% of the patients, respectively. The decrease in spirometry values from baseline was significantly greater in the interscalene block group.


The superior trunk block provided noninferior analgesia compared with interscalene brachial plexus block for up to 24 h after arthroscopic shoulder surgery and resulted in significantly less hemidiaphragmatic paresis.

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