Feasibility of lateral vs. transmuscular quadratus lumborum block in calves: a cadaver study

IMPORTANCE: The quadratus lumborum block (QLB) may provide locoregional analgesia of the trunk. OBJECTIVE: To investigate the feasibility of 2 ultrasound-guided QLB approaches - lateral (QLB-L) and transmuscular (QLB-T) - in calf cadavers. METHODS: Ten calf cadavers underwent bilateral QLB at L1 using QLB-L (n = 5) or QLB-T (n = 5). Each cadaver received 0.4 mL/kg on one side and 0.6 mL/kg on the other. A 1:2 iohexol:methylene blue mixture was injected under ultrasound guidance. Computed tomography and gross dissection assessed craniocaudal spread and staining of ventral rami and sympathetic trunk segments. RESULTS: The number of stained nerves was similar for both approaches. L1 and L2 were stained in all injections; T13 was stained in all but 1 QLB-L small-volume injection; T12 staining occurred most often with QLB-T small-volume injections (4/5) and in 2/5 injections in the remaining groups; T11 staining was limited (1/5 QLB-L and 2/5 QLB-T; both volumes); T10 to T4 staining occurred once (QLB-T large volume). CONCLUSIONS AND RELEVANCE: Both approaches were anatomically feasible in calf cadavers and produced injectate spread consistent with potential abdominal wall target coverage. Clinical trials are needed to determine analgesic efficacy and safety.