Introduction Interscalene brachial plexus blocks are a commonly performed procedure to reduce pain following total shoulder arthroplasty. Liposomal bupivacaine has been purported to prolong the duration of brachial plexus blocks for up to 72 hours; however, there has been controversy surrounding the analgesic benefits of this drug. Our hypothesis was that an interscalene block performed with bupivacaine alone would be non-inferior to a combination of liposomal bupivacaine and bupivacaine with respect to opioid consumption following total shoulder arthroplasty.
Methods Subjects presenting for primary total shoulder arthroplasty were randomized in a 1:1 ratio to an ultrasound-guided, single-injection interscalene block with either a combination of liposomal bupivacaine and bupivacaine (LB group) or bupivacaine without additive (Bupi group). The primary outcome of this study was 72-hour postoperative cumulative opioid consumption (in oral morphine equivalents) with a non-inferiority margin of 22.5 mg. Secondary outcomes included pain scores, patient satisfaction with analgesia and patient reported duration of sensory block.
Results Seventy-six subjects, 38 from the Bupi group and 38 from the LB group, completed the study. Analysis of the primary outcome showed a 72-hour cumulative geometric mean oral morphine equivalent consumption difference of 11.9 mg (95% CI −6.9 to 30.8) between groups (calculated on the log scale). This difference constitutes approximately 1.5 tablets of oxycodone over 3 days. No secondary outcomes showed meaningful differences between groups.
Discussion Interscalene brachial plexus blocks performed with bupivacaine alone did not demonstrate non-inferiority compared to a mixture of liposomal bupivacaine plus bupivacaine with regards to 72-hour cumulative opioid consumption following total shoulder arthroplasty. However, the difference between groups did not appear to be clinically meaningful.
- Acute Pain
- Brachial Plexus
Data availability statement
Data are available upon reasonable request.
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Contributors DAE, BCW, SFB and NAH: this author helped design the study, conduct the study, analyze the data and write the manuscript. JRC: this author helped conduct the study, analyze the data, and write the manuscript. CMR, PEA and AES: this author helped analyze the data and write the manuscript. DAE is responsible for the overall content and acted as the guarantor for this study.
Funding Department of Anesthesiology, University of Virginia, Charlottesville, VA, USA.
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.