ESRA19-0618 Vulnerability of different nerves to intrafascicular injection with different needle bevel types and needle angles: a mathematical model

Background and aims Intrafascicular injection of a local anesthetic, its toxicity, and direct needle trauma to nerve tissue are generally considered the primary reasons for nerve injury after intraneural injection. We hypothesize that the only way that the local anesthetic can enter the fascicle is if at least 80% of the distal needle orifice is inside the fascicle. the aim of this study was to calculate the theoretical vulnerability of nerve fascicles given their actual sizes and that of different needle openings. Methods We superimposed microscopic images of two routinely used nerve block needles (a 22-G, 15 ‘StimuplexOD’ needleand a 22-G, 30 ‘StimuplexOUltra 360O’ needle) over microscopi…