Combined paravertebral lumbar plexus and parasacral sciatic nerve block (L4-S2) with bupivacaine in the dog.

Studies in people suggest that parasacral sciatic block combined with paravertebral lumbar plexus block results in anesthesia of the entire lower extremity (Gaertner et al, 2004); our aim was to evaluate the effectiveness of this technique in awake dogs. Eight healthy dog (12.4 ± 4.5 kg) received the following treatments with ten days between each treatment: Placebo1- saline 0.2 ml kg-1, Placebo2- 0.4 ml kg-1, B1- 0.2 ml kg-1 bupivacaine 0.25%, B2- 0.2 ml kg-1 bupivacaine 0.5%, B3 0.4 ml kg-1 bupivacaine 0.25%. The total volume was equally divided in four aliquots (one per injection site: L4, L5, L6, Sacrum). After medetomidine administration (10 mcg kg-1 iv), nerve were located using an insulated needle connected to a nerve stimulator (intensity 0.5 mA, 0.1 millisecond). Ten minutes after atipamezole (0.05 mg kg-1 iv) administration, type (partial, absent or complete) and duration of sensitive blockade was determined with the response to prick test as described by clinical evaluation scale (Garcia-Fernandez et al, 2005). Areas considered were 3rd phalange for peroneal nerve and skin over caudal metatarsus for tibial nerve. Data were analyzed using ANOVA and Dunn´s post hoc tests and differences between peroneus and tibial nerves were determinate by a t-student test (Wilcoxon). Partial and complete effects (global blockade) and complete sensitive block (complete blockade) on its own were registered with higher percentage in group B2 compared with other groups (see table). Duration of global blockade was significantly lower in B1 group compared with group B2. In conclusion with this technique sensitive peroneal and tibial nerves blockade appears similar in effect and duration, meanwhile it seems that bupivacaine 0.5% is more effective in order to obtain a complete block.