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Clinical Trial
. 2025 Apr;134(4):1153-1160.
doi: 10.1016/j.bja.2024.12.010. Epub 2025 Jan 23.

Respiratory impact of local anaesthetic volume after interscalene brachial plexus block with extrafascial injection: a randomised controlled double-blinded trial

Yves Renard  1 , Sina Grape  2 , Erin Gonvers  1 , Jean-Benoit Rossel  3 , Patrick Goetti  4 , Eric Albrecht  5
Affiliations
Clinical Trial

Respiratory impact of local anaesthetic volume after interscalene brachial plexus block with extrafascial injection: a randomised controlled double-blinded trial

Yves Renard et al. Br J Anaesth. 2025 Apr.

Abstract

Background: We have previously demonstrated that an extrafascial injection of 20 ml of local anaesthetic for interscalene brachial plexus block (ISB) reduces the rate of hemidiaphragmatic paralysis by 70% compared with an intrafascial injection, with similar efficacy. In this double-blind trial, we tested the hypothesis that a local anaesthetic volume of 10 ml injected extrafascially would reduce the rate of hemidiaphragmatic paralysis vs a volume of 20 ml, while providing similar analgesia.

Methods: Sixty ASA physical status 1-3 patients scheduled for elective shoulder surgery under general anaesthesia were randomised to receive ultrasound-guided extrafascial ISB using ropivacaine 0.75% 20 ml (control group) or 10 ml (low-volume group) injected lateral to the brachial plexus sheath. The primary outcome was incidence of hemidiaphragmatic paralysis (diaphragmatic excursion reduction of >75%), measured by M-mode ultrasonography, at 30 min after the procedure. Secondary outcomes included duration of analgesia and i.v. morphine consumption at 24 h after surgery.

Results: The 30-min hemidiaphragmatic paralysis rate was 80% (95% confidence interval [CI] 61-91%) in the control group and 19% (95% CI 8-40%) in the low-volume group (P<0.001). Participants in the low-volume vs control group had a shorter duration of analgesia (550 vs 873 min; P<0.01) and higher i.v. morphine consumption (20 vs 12 mg; P=0.03).

Conclusions: A low volume of local anaesthetic injected extrafascially reduced the rate of hemidiaphragmatic paralysis, but at the expense of a shorter duration of analgesia compared with standard-dose extrafascial anaesthetic injection.

Clinical trial registration: NCT04726280.

Keywords: brachial plexus block; diaphragm; pain; postoperative analgesia; regional anaesthesia.

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Conflict of interest statement

Declaration of interest EA received grants from the Swiss Academy for Anesthesia Research (SACAR) and the Swiss National Science Foundation, Bern, Switzerland to support his clinical research. All other authors declare no competing interests.

Figures

Fig 1
Fig 1
Ultrasound-guided interscalene brachial plexus block with an extrafascial injection: needle tip position at a distance of 4 mm from the lateral border of the brachial plexus sheath; C5, C5 root; C6, C6 root; C7, C7 root.
Fig 2
Fig 2
Patient flow chart.
Fig 3
Fig 3
Kaplan–Meier curve showing the duration of analgesia based on the volume of local anaesthetic injected (20 ml [control] vs 10 ml [low volume]).
See this image and copyright information in PMC

References

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