Introduction Hemidiaphragmatic paresis after ultrasound-guided supraclavicular brachial plexus block is reported to occur in up to 67% of patients. We tested the hypothesis that an injection outside the brachial plexus sheath reduces the incidence of hemidiaphragmatic paresis compared with an intrafascial injection while providing similar analgesia.
Methods Fifty American Society of Anesthesiologists I–III patients scheduled for elective upper limb surgery received a supraclavicular brachial plexus block using 30 mL of 1:1 mixture of mepivacaine 1% and ropivacaine 0.5%. The block procedures were randomized to position the needle tip either within the brachial plexus after piercing the sheath (intrafascial injection) or outside the brachial plexus sheath (extrafascial injection). The primary outcome was the incidence of hemidiaphragmatic paresis 30 min after the injection, measured by M-mode ultrasonography. Additional outcomes included time to surgery readiness, and resting and dynamic pain scores at 24 hours postoperatively (Numeric Rating Scale, 0–10).
Results The incidence of hemidiaphragmatic paresis 30 min after the injection was 9% (95% CI 1% to 29%) and 0% (95% CI 0% to 15%) in the intrafascial and extrafascial groups respectively (p=0.14). Extrafascial injection was associated with a longer time to surgery readiness (intrafascial: 18 min (95% CI: 16 to 21 min); extrafascial: 37 min (95% CI: 31 to 42 min); p<0.001). At 24 hours, resting and dynamic pain scores were similar between groups.
Discussion Ultrasound-guided supraclavicular brachial plexus block with an extrafascial injection does not reduce the incidence of hemidiaphragmatic paresis although it provides similar analgesia, when compared with an intrafascial injection. The longer time to surgery readiness is less compatible with contemporary operating theater efficiency requirements.
Trial registration number NCT03957772.
- brachial plexus
- pain, postoperative
Data availability statement
Data are available on reasonable request.
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Contributors SG: study design, study registration, block performance, manuscript editing; KK: data interpretation, manuscript editing; NZ: patient recruitment, data collection; AB: data interpretation, manuscript editing; EA: study design, statistical analysis, data interpretation, manuscript preparation. EA is the guarantor and takes full responsibility for the conduct of the study and the finished work. Moreover, EA has access to the data, and controlled the decision to publish.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests EA received grants from the Swiss Academy for Anesthesia Research (SACAR), Lausanne, Switzerland, B. Braun Medical AG, Sempach, Switzerland and the Swiss National Science Foundation, Bern, Switzerland to support his clinical research. EA has also received an honorarium from B. Braun Medical AG Switzerland, Sintetica UK and MSD AG Switzerland. SG received a research grant and an honorarium from MSD AG Switzerland.
Provenance and peer review Not commissioned; externally peer reviewed.