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

Abstract

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.

Use of wound infusion catheters for postoperative local anaesthetic administration in cats

“…Recently, local anaesthetic systemic toxicity associated with bupivacaine administration has been reported in two cats. 36 , 37 In the first case, bupivacaine was accidentally overdosed (10 mg/kg) during intrapleural administration. 36 In the second case, bupivacaine was delivered epidurally through an epidural catheter over several days, causing toxicity due to accumulation.…”

“… 36 In the second case, bupivacaine was delivered epidurally through an epidural catheter over several days, causing toxicity due to accumulation. 37 However, there are no reports of severe neurotoxicity after subcutaneous or intramuscular administration of LA in cats.…”

Successful treatment of local anaesthetic toxicity using intralipid 20% emulsion following intrathoracic bupivacaine overdose in a cat

“…A case of cumulative bupivacaine leading to signs of LAST has been recently reported following repeat administration of bupivacaine via an epidural catheter in a cat, although the cumulative dose is not clearly reported. 20 Toxic effects from single-dose administration have been reported at doses over 2 mg/kg perineurally and from 1 to 5 mg/kg IV; however, there are case reports of cats developing signs of bupivacaine toxicity at doses as low as 1.16 mg/kg following perineural administration within highly absorptive areas. 1 , 21 The toxic dose is not specifically established for intrapleural administration.…”