Prolonged neuromuscular blockade in a horse following concomitant use of vecuronium and atracurium.

This research article discusses a case wherein the concomitant administration of vecuronium and atracurium resulted in an extended neuromuscular blockade (NMB) in a horse. The detailed report provides an in-depth analysis of the entire medical procedure carried out on the horse and the unusual consequences the medication combination led to.

Background

• The research centers around a case where a 7-year-old Irish Sports Horse was treated for corneal laceration.
• Various drugs like Acepromazine, romifidine, Gentamycin, ketamine, and diazepam were administered for sedation and anesthesia. The horse was then put on ventilator support and sevoflurane was used to maintain anesthetic state.
• Additionally, neuromuscular function was assessed using an acceleromyograph.

Use of Vecuronium and Atracurium

• During the procedure, the horse was administered with an initial dose of Vecuronium. Five minutes after the Vecuronium administration, twitching was noticed but there were no alterations in eye position.
• Atracurium was introduced afterward, After two minutes of its administration, absence of twitches was recorded and the globe of the eye of the horse was observed at a central position.

Observations Post Administration

• The surgical repair was completed within 20 minutes of atracurium administration.
• However, 52 minutes post atracurium administration, twitching was observed again.
• The train of four ratio (T4/T1 ratio), which is a measure of neuromuscular blockade, failed to exceed 0.5 even after the administration of edrophonium, a drug used to reverse the effects of neuromuscular blockade.

Interpretation and Conclusion

• Following multiple administrations of edrophonium in the next hour, the T4/T1 ratio fluctuated but eventually settled above 0.9, indicating that the neuromuscular blockade had been successfully reversed.
• Therefore, even if the eventual recovery from anaesthesia was smooth, the researchers noted that the neuromuscular blockade (NMB) lasted longer than expected, likely due to the concomitant use of vecuronium and atracurium.
• The research suggests that the combination of vecuronium and atracurium may lead to an extended neuromuscular blockade in horses, implying that veterinary practitioners should exercise caution when using this combination of drugs.