Ultrasound-guided caudal quadratus lumborum block combined with the greater ischiatic notch plane block as motor-protective analgesia for the pelvic limb in dogs

Abstract

Objective To develop an ultrasound-guided caudal quadratus lumborum block (C-QLB) technique in canine cadavers and to compare sensory and motor blockaderesulting from the combination of ultrasound-guidedgreater ischiatic notch (GIN) plane and C-QLB approaches(GIN-CQLB group) versus a lumbosacral plexus (LSP group)approach [combination of lateral pre-iliac (LPI) and parasacral (PS) techniques] in dogs.Study design Descriptive anatomical study and prospectiverandomized, blinded, experimental crossover trial.Animals A total of six canine cadavers and six adult Beagledogs.Methods Phase I: following ultrasound-guided C-QLB injections of 0.3 mL kge1 of dye, using the interfascial planelocated lateral to the quadratus lumborum muscle at thelevel of the sixth lumbar vertebra (L6) as injection point, thespread of injectate and nerve staining was evaluated usinggross anatomical dissection. Phase II: sensory and motorblockade achieved with the GIN-CQLB or LSP blocks inBeagle dogs were evaluated and compared. The assignedtechnique was performed with 2% lidocaine: 0.2 mL kge1for the GIN and PS approaches and 0.3 mL kge1 for the CQLB and LPI approaches.Results Dissection revealed distribution of dye around thelumbar hypaxial musculature, extending into the paravertebral spaces, with staining of 3 (2e4) [median(interquartile range)] spinal nerves, spanning L3 to L6. Themedian motor blockade in the GIN-CQLB and LSP groupswas 7 (7e8) versus 16 (10e16) (p ¼ 0.026), whereas themedian sensory blockade was 5 (4e5) versus 3 (3e3) (p ¼0.025), respectively.Conclusion and clinical significance The GIN-CQLBapproach desensitized the thigh dermatomes effectively.Compared with the LSP approaches, GIN-CQLB exhibits amotor-protective effect by preserving tonic muscle function.