Effects of lidocaine administration via continuous rate infusion on the minimum alveolar concentration of isoflurane in New Zealand White rabbits (Oryctolagus cuniculus)

• Autores: Rodney W. Schnellbacher, James W. Carpenter, Butch KuKanich
• Localización: American Journal of Veterinary Research, ISSN-e 1943-5681, ISSN 0002-9645, Vol. 74, Nº. 11, 2013, págs. 1377-1384
• Idioma: inglés
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• Resumen

  • Objective—To evaluate the effect of a continuous rate infusion (CRI) of lidocaine on the minimum alveolar concentration (MAC) of isoflurane in rabbits.

    Animals—Five 12-month-old female New Zealand White rabbits (Oryctolagus cuniculus).

    Procedures—Rabbits were anesthetized with isoflurane. Baseline isoflurane MAC was determined by use of the tail clamp technique. A loading dose of lidocaine (2.0 mg/kg, IV) was administered followed by a CRI of lidocaine at 50 μg/kg/min. After 30 minutes, isoflurane MAC was determined. Another loading dose was administered, and the lidocaine CRI then was increased to 100 μg/kg/min. After 30 minutes, isoflurane MAC was determined again. Plasma samples were obtained for lidocaine analysis after each MAC determination.

    Results—Baseline isoflurane MAC was 2.09%, which was similar to previously reported values in this species. Lidocaine CRI at 50 and 100 μg/kg/min induced significant reductions in MAC. The 50 μg/kg/min CRI resulted in a mean plasma lidocaine concentration of 0.654 μg/mL and reduction of MAC by 10.5%. The 100 μg/kg/min CRI of lidocaine resulted in a mean plasma concentration of 1.578 μg/mL and reduction of MAC by 21.7%. Lidocaine also induced significant decreases in arterial blood pressure and heart rate. All cardiopulmonary variables were within reference ranges for rabbits anesthetized with inhalation anesthetics. No adverse effects were detected; all rabbits had an uncomplicated recovery from anesthesia.

    Conclusions and Clinical Relevance—Lidocaine administered as a CRI at 50 and 100 μg/kg/min decreased isoflurane MAC in rabbits. The IV administration of lidocaine may be a useful adjunct in anesthesia of rabbits.