Systemic and local effects of lidocaine or mepivacaine when used for intravenous regional anaesthesia of the distal limb in standing sedated horses.
Authors: Mendez-Angulo Jose L, Granados Maria M, Modesto Rolf, Serrano-Rodriguez Juan M, Funes Francisco J, Quiros Setefilla, Gomez-Villamandos Rafael J, Zaldívar Sara, Trumble Troy N
Journal: Equine veterinary journal
Summary
# Editorial Summary Intravenous regional limb perfusion (IVRLP) with local anaesthetics is increasingly used clinically alongside antibiotics for distal limb surgery in standing sedated horses, yet evidence supporting its analgesic efficacy and safety profile remains limited. Researchers administered lidocaine or mepivacaine via IVRLP to six horses in a crossover design, measuring nociceptive thresholds using electrical and mechanical stimuli, alongside plasma and synovial fluid drug concentrations over 24 hours. Both agents achieved effective anti-nociception within 10 minutes and maintained it throughout the 30-minute tourniquet application—comparable to perineural nerve blocks—with plasma concentrations remaining safely below 50 ng/mL during tourniquet occlusion; however, analgesia declined gradually after tourniquet release, whereas perineural blocks sustained protection beyond one hour. Peak synovial fluid concentrations occurred 25 minutes post-injection, confirming local tissue penetration. For practitioners, these findings validate IVRLP with either agent as a reliable tourniquet-dependent analgesic technique for distal limb procedures in standing horses, whilst reassuring on systemic safety margins, though the shorter duration post-release compared to perineural approaches should inform case planning and supplementary analgesia decisions.
Read the full abstract on PubMed
Practical Takeaways
- •IVRLP with lidocaine or mepivacaine provides effective anti-nociception comparable to perineural anaesthesia for distal limb procedures in standing sedated horses during the 30-minute tourniquet application window.
- •Both local anesthetics maintain safe plasma and synovial fluid concentrations, making either suitable for clinical use; plan procedural timing around the 30-minute effective window post-injection.
- •Following tourniquet release, expect gradual return of sensation within one hour with IVRLP, so schedule post-operative analgesics and monitoring accordingly.
Key Findings
- •Lidocaine and mepivacaine via IVRLP significantly increased nociceptive thresholds at 10, 20, and 30 minutes, equivalent to perineural anaesthesia, with no difference between the two local anesthetics.
- •Plasma concentrations of both agents remained ≤50 ng/mL while tourniquet was applied, significantly increasing 10 minutes after release, indicating safe systemic levels during the procedure.
- •After tourniquet release at 30 minutes, anesthesia from IVRLP gradually returned to baseline within one hour, whereas perineural anaesthesia remained effective beyond one hour.
- •Maximal synovial fluid concentrations were reached 25 minutes after IVRLP injection, with concentrations remaining below toxic levels throughout the study period.