Ultrasound-Guided Regional Anaesthesia: Visualising the Nerve and Needle

James Bowness (Lead / Corresponding author), Alasdair Taylor

    Research output: Chapter in Book/Report/Conference proceedingChapter (peer-reviewed)peer-review

    14 Citations (Scopus)

    Abstract

    Regional anaesthesia involves targeting specific peripheral nerves with local anaesthetic. It facilitates the delivery of anaesthesia and analgesia to an increasingly complex, elderly and co-morbid patient population. Regional anaesthesia practice has been transformed by the use of ultrasound, which confers advantages such as accuracy of needle placement, visualisation of local anaesthetic spread, avoidance of intraneural injection and the ability to accommodate for anatomical variation.

    An US beam is generated by the application of electrical current to an array of piezoelectric crystals, causing vibration and consequential production of high-frequency sound waves. The sound energy is reflected at tissue interfaces, detected by the piezoelectric crystals in the ultrasound probe, and most frequently displayed as a 2D image.

    Optimising image acquisition involves selection of the appropriate US frequency: this represents a trade-off between image resolution (better with high frequency) and tissue penetration/beam attenuation (better with low frequency). Altering alignment, rotation and tilt of the probe is often required to optimise the view as nerves are best visualised when the ultrasound beam is directly perpendicular to their fibres. Adjusting the focus, depth, and gain (brightness) of the image display can also help in this matter.

    Three key challenges exist in regional anaesthesia; image optimisation, image interpretation (nerve visualisation) and needle visualisation. There are characteristic sonographic appearances of the nerve structures for peripheral nerve blocks, as discussed in this chapter, and the above techniques can be used to enhance their appearance. Much research has been done, and is ongoing, with the aim of improving needle visualisation; this is also reviewed. Image interpretation requires the application of anatomical knowledge and understanding of the typical sonographic appearance of different tissues (as well as the needle). Years of practice are required to attain expertise, although it is hoped that continuing advances in nerve and needle visualisation, as described in this chapter, will expedite that process.

    Original languageEnglish
    Title of host publicationBiomedical Visualisation
    EditorsPaul M. Rea
    Place of PublicationSwitzerland
    PublisherSpringer
    Pages19-34
    Number of pages16
    Volume6
    ISBN (Electronic)9783030376390
    ISBN (Print)9783030376383
    DOIs
    Publication statusPublished - 2020

    Publication series

    NameAdvances in Experimental Medicine and Biology
    ISSN (Print)0065-2598
    ISSN (Electronic)2214-8019

    Keywords

    • Ankle
    • Ankle joint
    • Foot
    • Local anaesthetics
    • Nerve block
    • Ultrasonography

    ASJC Scopus subject areas

    • Orthopedics and Sports Medicine

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