Effects of constant rate infusion of lidocaine and ketamine, with or without morphine, on isoflurane MAC in horses.
Authors: Villalba M, Santiago I, Gomez de Segura I A
Journal: Equine veterinary journal
Summary
# Editorial Summary: Isoflurane-Sparing Effects of Lidocaine, Ketamine and Morphine in Equine Anaesthesia Maintaining stable, light planes of anaesthesia whilst minimising volatile agent exposure is a longstanding challenge in equine surgery, as excessive isoflurane carries metabolic and recovery costs. Villalba and colleagues investigated whether constant rate infusions (CRI) of lidocaine and ketamine—with or without morphine—could reduce the minimum alveolar concentration (MAC) of isoflurane needed to maintain surgical anaesthesia in horses. Using a randomised crossover design, the team measured isoflurane MAC requirements under four protocols: lidocaine-ketamine alone, lidocaine-ketamine-morphine, and two control comparisons, assessing haemodynamic stability and recovery quality alongside anaesthetic depth. Both lidocaine-ketamine and the three-drug combination significantly reduced isoflurane MAC requirements, though morphine's addition provided no further sparing effect, whilst maintaining excellent cardiovascular stability and promoting smooth recoveries. For practitioners, this finding validates CRI protocols with lidocaine and ketamine as effective tools for reducing isoflurane exposure during routine and prolonged equine procedures, potentially lowering postoperative complications, though the addition of morphine offers no additional anaesthetic advantage despite its other recovery benefits.
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Practical Takeaways
- •Using lidocaine and ketamine infusions during isoflurane anaesthesia in horses allows you to reduce inhalation anaesthetic depth, lowering costs and improving recovery quality
- •Adding morphine to the lidocaine-ketamine combination provides additional anaesthetic sparing without compromising cardiovascular or respiratory stability
- •This multimodal approach enables lighter, safer anaesthesia with improved post-operative analgesia in equine patients
Key Findings
- •Lidocaine and ketamine constant rate infusion reduce isoflurane MAC in horses
- •Morphine addition to lidocaine-ketamine CRI further decreases isoflurane MAC requirements
- •Triple drug combination (lidocaine, ketamine, and morphine) demonstrates isoflurane-sparing effect without adverse haemodynamic and ventilatory changes
- •Morphine CRI improves recovery quality when used with isoflurane anaesthesia in horses