The effect of an ultrasound-activated needle tip tracker needle on the performance of sciatic nerve block on a soft embalmed Thiel cadaver.

Abstract

In this study, we measured the performance of medical students and anaesthetists using a new tracker needle during simulated sciatic nerve block on soft embalmed cadavers. The tracker needle incorporates a piezo element near its tip that generates an electrical signal in response to insonation. A circle, superimposed on the ultrasound image surrounding the needle tip, changes size and colour according to the position of the piezo element within the ultrasound beam. Our primary objective was to compare sciatic block performance with the tracker switched on and off. Our secondary objectives were to record psychometrics, procedure efficiency, participant self-regulation and focused attention using eye-tracking technology. Our primary outcome measures were the number of steps successfully performed and the number of errors committed during each block. Videos were scored by trained experts using validated checklists. Sequential tracker activation and deactivation was randomised equally within subjects. With needle activation, steps improved in 10 (25%) subjects and errors reduced in six (15%) subjects. The most important steps were: needle tip identification before injection, OR (95%CI) 2.12 (1.61-2.80; p<0.001); and needle tip identification before advance of the needle, 1.80 (1.36-2.39; p<0.001). The most important errors were: failure to identify the needle tip before injection, 2.40 (1.78-3.24; p<0.001); and failure to quickly regain needle tip position when tip visibility was lost, 2.03 (1.5-2.75; p<0.001). In conclusion, needle-tracking technology improved performance in a quarter of subjects.