References
Comparing approaches to sciatic nerve blocks in dogs during tibial plateau-levelling osteotomy
Abstract
The aim of this study was to compare the postoperative analgesic requirements in dogs receiving a sciatic nerve block by either the lateral or transgluteal approach. The secondary aim was to determine if there was a difference in ease of performing the nerve block. Forty-two client-owned dogs were used in this study. Sciatic nerve block was performed by the transgluteal approach (group A), or the lateral approach (group B) combined with a psoas compartment block. All blocks were performed using a nerve stimulator and 0.1 ml/kg bupivacaine 0.5%, per block. The time taken to perform the sciatic nerve block, number of attempts, the current (mA), and intraoperative and postoperative opioid requirements were recorded. Overall, 52% of dogs required methadone intraoperatively, with no difference between groups (P=0.516). Postoperatively, 24% in group A and 12% in group B required methadone (P=0.314). There was no difference in the time taken to perform the sciatic nerve block, current or the number of attempts between groups. Both approaches to the sciatic nerve block conferred similar levels of analgesia and may be used as part of a multimodal analgesic protocol for dogs undergoing pelvic limb surgery.
The use of peripheral nerve blocks in people is an effective technique to provide intraoperative and postoperative analgesia (Roberts and Cowen, 2016; Hutton et al, 2018). There are increasing numbers of publications detailing techniques for performing peripheral nerve blocks in dogs, specifically in comparison to other well-established locoregional anaesthesia techniques such as epidural anaesthesia (Campoy et al, 2012).
The pelvic limb is innervated by the lumbar and sacral plexuses, which in turn give rise to the femoral and sciatic nerve, respectively (Gurney and Leece, 2014). When a local anaesthetic is instilled around these nerves, analgesia can be provided to the majority of the pelvic limb (Dyce et al, 2010; Portela et al, 2018). Multiple approaches can be used to instil local anaesthetic around the sciatic nerve, which can affect the structures blocked. Overall, the sciatic nerve block performed by any technique should result in anaesthesia of the caudolateral stifle, some intra-articular structures, joint capsule, tibia, tarsus, metatarsus and digits. The lateral approach will also result in anaesthesia of the muscular branch. The transgluteal approach provides anaesthesia of the ischiotibial muscles and some sensory branches of the coxofemoral joint (Campoy and Mahler, 2013). The lateral pre-iliac approach to the psoas compartment should provide anaesthesia of the hemipelvis, femur, femorotibial joint, skin of the dorsomedial tarsus and first digit (Campoy and Mahler, 2013; Portela et al, 2013a, 2013b).
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