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Challenges, solutions, and advances in ultrasound-guided regional anaesthesia

M Henderson MB ChB, FRCA, J Dolan BSc (Hons), MSc (Distn), PhD, MB ChB, FFARCSI, EDRA
DOI: http://dx.doi.org/10.1093/bjaed/mkw026 374-380 First published online: 19 May 2016
  • 2G03
  • 3A09

Key points

  • Challenges to successful ultrasound-guided regional anaesthesia include the acquisition of acceptable ultrasound images of the nerve while avoiding artifacts.

  • The most common ultrasound artifacts are acoustic or anatomic.

  • Physiological and pathological factors attributable to the patient affect image quality and interpretation.

  • Needle artifacts may cause confusion and error during ultrasound-guided nerve blocks.

  • The combination of ultrasound guidance and peripheral nerve stimulation, ‘dual guidance’, may offer reassurance when the nerve or needle image is suboptimal.

Ultrasonography offers significant advantages in the practice of regional anaesthesia, including faster sensory onset and improved success rates compared with landmark-based techniques.1 Adequate visualization of neural and surrounding structures together with monitoring the spread of local anaesthetic (LA) are absolute prerequisites for the safe and successful practice of ultrasound-guided regional anaesthesia (USGRA). The creation of an ultrasound (US) image is based on the physical properties of the US beam formation, propagation of sound in matter, interaction of sound with reflective interfaces, echo detection, and machine processing. However, there are often a number of significant challenges to acquiring the optimal US images necessary to achieve successful nerve blocks. Such challenges include the acquisition and interpretation of optimal US images of the target structure and needle while avoiding tissue and needle artifacts. Other difficulties may include physiological, pathological, and anatomical factors attributable to the patient and which may affect image quality and interpretation. This article will describe some of these problems, discuss strategies to avoid them, and highlight current and future advances which may assist the practice of USGRA.

Challenges presented by the ultrasound machine

The spatial resolution of any imaging system is defined as its ability to distinguish two points as separate entities in space. Spatial resolution is commonly subcategorized into axial and lateral resolution.2 Axial resolution is defined as the US machine's ability to differentiate two objects located at different …

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