Suspected local anaesthetic systemic toxicity (LAST) after several bupivacaine injections through an epidural catheter in a cat

摘要

A 9-year-old male neutered domestic short hair cat was referred to our practice after a road traffic accident. On presentation, the cat was obtunded, with bilateral hindlimb fractures. The fractures were surgically repaired, and an epidural catheter was placed for perioperative pain management. Postoperative analgesia consisted of bupivacaine administered intermittently through the epidural catheter. In the days after surgery, the cat became duller and more obtunded, and marked bilateral mydriasis with absence of a pupillary reflex was noted. After ruling out different causes for mydriasis and weaning the cat from systemic opioids, local anaesthetic systemic toxicity (LAST) emerged the primary differential diagnosis. Bupivacaine plasma concentrations were measured and found a fourfold increase in concentration over that reported after a perineural block. Mydriasis and absent pupillary light reflex, among other clinical signs, could be early indicators of LAST secondary to accumulation of the local anaesthetic in patients with an epidural catheter.