Ultrasound‐guided interscalene blocks: understanding where to inject the local anaesthetic

• Published in: Anaesthesia 2011-06, Vol.66 (6), p.509-514
• Main Authors: Spence, B. C., Beach, M. L., Gallagher, J. D., Sites, B. D.
• Format: Article
• Language: English
• Subjects: Adult; Aged; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthetics, Local - administration & dosage; Arthroscopy; Biological and medical sciences; Brachial Plexus - diagnostic imaging; Clinical trials; Comparative studies; Female; Humans; Injections; Male; Medical sciences; Middle Aged; Movement - drug effects; Nerve Block - methods; Sensation - drug effects; Shoulder; Shoulder Joint - surgery; Surgery; Ultrasonography, Interventional - methods
• ISSN: 0003-2409; 1365-2044
• DOI: 10.1111/j.1365-2044.2011.06712.x

Summary Although ultrasound‐guided regional anaesthesia has gained in popularity, few data exist describing the optimal location(s) to inject local anaesthetic. Our objective was to compare, for interscalene blocks, the effectiveness of an injection between the middle scalene muscle and brachial plexus sheath (peri‐plexus) with an injection within the brachial plexus sheath (intra‐plexus). We enrolled 170 patients undergoing shoulder surgery with general anaesthesia and interscalene block in this randomised, controlled trial. Our primary outcome variable was loss of shoulder abduction. Block quality was also measured and defined by an evaluation of onset time, sensory and motor loss and duration. There was no difference between the two groups in block onset times or block quality. After adjusting for sex, age and volume injected, intra‐plexus blocks lasted a mean of 2.6 h (16%) longer (95% CI 0.25–5.01, p = 0.03) than peri‐plexus blocks.