Article Text
PDF
Abstract
Background and Aims Ultrasound-guided regional anaesthesia requires needling expertise to minimise the risk of nerve damage – the needle tip should be neither too far from the nerve nor within the nerve, but in the “near-nerve” zone. Whilst block phantoms exist to allow trainees to learn this skill without putting patients at risk, generally they do not provide feedback as to needle tip position relative to the nerve – the trainee may think they are visualising the tip but actually it may be somewhere else.
Methods ADAMgel (Aqueous Dietary fibre Antifreeze Mix gel, a tissue-simulating ultrasound medium [1]) was used to form a tubular coating (representing the near-nerve zone) around a copper rod (the nerve), then wrapped in an insulating layer. This was embedded in more ADAMgel, along with a fluid-filled balloon to simulate a blood vessel. A latex sheet formed the skin. Electrodes connected to the ADAMgel layers, the copper nerve, and the needle tip were fed to an Arduino programmable microcontroller, which was connected to a liquid-crystal display (LCD) (Figure 1). C++ code uploaded to the Arduino allowed it to detect change in resistance as the needle tip advanced through the layers.
Results When a needle with conducting tip was advanced through the ADAMgel towards the nerve, the LCD indicated whether the distance from the nerve was >10mm,≤10mm, or touching the nerve (Figure 2).
Conclusions A prototype block phantom with needle-position feedback was created. With further refinement, for example reducing the near-nerve zone to 3mm, this offers the potential to improve needling technique training.