Choice of Needle and Injection Rate for Fascial Plane Injection: a Randomised Controlled Study in the Soft-Embalmed Thiel Cadaver

Editor—Fascial plane blocks show variable efficacy. Spread of local anaesthetic is unpredictable, yet physical mechanisms have not been investigated.1,2 There is a need to understand how fascial plane blocks both work and fail to guide clinical practice and research.3,4 We hypothesised that: (1) injection through single-bevelled needles generate higher pressures than through Tuohy needles; (2) higher pressures are associated with reduced tissue displacement; (3) fascial penetration meets with a wide range of needle-tip insertion forces; and (4) the soft-embalmed Thiel cadaver is a robust model of repeated injection.