Neuromuscular block monitoring after the administration of 1mg/kg intravenous cis-atracurium in the anaesthetized pig.

Abstract

Neuromuscular blocking agents should be included as part of a balanced anaesthetic protocol to improve anaesthetic management, although doses are not always established for each species. Cis-atracurium is a benzylisoquinolinium neuromuscular blocking agent with an intermediate duration of action devoid of significant adverse effects previously used in pigs with a wide dosage range. Cis-atracurium was administered at 1mg/kg bolus to sixteen pigs to establish its time profile and effects. The pigs were premedicated intramuscularly with 4mg/kg azaperone, 8mg/kg ketamine and 0.2mg/kg morphine IM and maintained with isoflurane in oxygen. After cis-atracurium administration, neuromuscular monitoring via acceleromyography was started until the recovery of the 90% of the train of four ratio. Complete decrease in the train of four ratio was accomplished in eleven pigs. Onset of action was 70s, with a recovery of the fourth twitch at 26min and a recovery of a train of four ratio greater than 90% in 60min. In conclusion, 1mg/kg intravenous cis-atracurium in the pig allowed for a rapid onset of action and a complete recovery after 60min although high variability in the time profile is seen.