Blood concentration of bupivacaine and duration of sensory and motor block following ultrasound-guided femoral and sciatic nerve blocks in dogs

Abstract

Peripheral nerve blocks are becoming increasingly popular for perioperative use as anesthetics and analgesics in small animals. This prospective study was performed to investigate the duration of motor and sensory blockade following use of bupivacaine for ultrasound-guided femoral and sciatic nerve blocks in dogs and to measure the plasma concentrations of bupivacaine that result from these procedures. Six dogs were anesthetized twice using a randomized cross-over design. At the first anesthetic, dogs were assigned to receive either an ultrasound-guided femoral nerve block or sciatic nerve block with 0.15 mL kg-1 of bupivacaine 0.5%. Two months later, the other nerve block was performed during a second anesthetic. At 5, 10, 15, 20, 30 and 60 minutes after injection, arterial blood samples were collected for laboratory measurement of bupivacaine. After 60 minutes, dogs were recovered from anesthesia. Starting at two hours post-injection, video-recordings of the dogs were made every two hours for 24 hours. The videos were randomized and the degree of motor and sensory blockade was evaluated using a three-point scoring system (0 = no effect, 1 = mild effect, 2 = complete blockade) by two blinded assessors. The median (range) times to full recovery from motor blockade were 11 (6–14) hours (femoral) and 12 (4–18) hours (sciatic), and 15 (10–18) hours (femoral) and 10 (4–12) hours (sciatic) for sensory blockade. There were no differences in the median times to functional recovery for the two techniques. Plasma concentrations of bupivacaine were no different following the blocks and were less than 0.78 μg mL-1 at all times. These results suggest that these ultrasound-guided nerve blocks do not result in potentially toxic systemic levels of local anesthetic and that their duration of action is useful for providing anesthesia and analgesia for pelvic limb procedures.

Opioid requirements after locoregional anaesthesia in dogs undergoing tibial plateau levelling osteotomy: a pilot study

“…In animals, the technique of ultrasound guidance for the blockade of large peripheral nerves such as the sciatic and the femoral nerves have been described in anatomical studies (Campoy et al 2010;Shilo et al 2010). The large majority of studies describing ultrasound-guided sciatic and femoral nerve block were performed on cadavers, experimental or healthy dogs (Costa-Farr e et al 2011;Cathasaigh et al 2018;Marolf et al 2019). Ultrasound-guided sciatic and femoral nerve blocks are now commonly used in clinical practice to control nociception in canine patients undergoing pelvic limb surgery (Campoy et al 2012).…”

Analgesic efficacy of a bilateral erector spinae plane block versus a fentanyl constant rate infusion in dogs undergoing hemilaminectomy: a retrospective cohort study

“…During the first 12 hours methadone requirement was reduced, but no difference was found between 12 and 24 hours. Therefore, it is plausible that the effect recorded was related to the duration of the levobupivacaine [ 34 ]. Nevertheless, the postoperative analgesic protocol was not standardised, and multiple contributing factors should be considered.…”

Evaluation of targeted bupivacaine for reducing acute postoperative pain in cats undergoing routine ovariohysterectomy

“…One attractive property of bupivacaine is its long duration of action. In veterinary medicine, bupivacaine’s duration of action is commonly reported to be 4–6 h. 7 In a recent report in dogs, the median time to return of full recovery from sensory blockage was up to 15 h. 26 There are numerous reports in humans of bupivacaine lasting ⩾8 h, and, although equivocal, there is a reported period of analgesia persisting after the return of sensation. 7,27,28 With this long duration of action, bupivacaine potentially reduces the need for opioid analgesics postoperatively.…”