Evaluation of the isoflurane-sparing effects of lidocaine infusion during umbilical surgery in calves

Abstract

ObjectiveTo evaluate the isoflurane-sparing effects of lidocaine administered by constant rate infusion (CRI) during umbilical surgery in calves. Study designRandomized ‘blinded’ prospective clinical study. AnimalsThirty calves (mean 4.7 ± SD 2.5 weeks old) undergoing umbilical surgery. MethodsAfter premedication with xylazine (0.1 mg kg−1, IM), anaesthesia was induced with ketamine (4 mg kg−1, IV) and maintained with isoflurane in O2 administered through a circle breathing system. The calves were assigned randomly to receive a bolus of 2 mg kg−1 lidocaine IV after induction of anaesthesia, followed by CRI of 50 μg kg−1 minute−1 (group L, n = 15) or a bolus and CRI of 0.9% sodium chloride (NaCl, group S, n = 15). End-tidal isoflurane was adjusted to achieve adequate depth of anaesthesia. Heart rate, direct arterial blood pressure and body temperature were measured intraoperatively. Groups were compared by t- tests, anova or Mann–Whitney rank sum test as appropriate. ResultsThe end-tidal concentration of isoflurane (median, IQR) was significantly lower in group L [1.0% (0.94–1.1)] compared to group S [1.2% (1.1–1.5)], indicating a 16.7% reduction in anaesthetic requirement during lidocaine CRI. Cardiopulmonary parameters and recovery times did not differ significantly between groups. Conclusion and clinical relevanceLidocaine CRI may be used as a supplement to inhalation anaesthesia during umbilical surgery in calves in countries where such a protocol would be within the legal requirements for veterinary use in food animals. This study did not show any measurable benefit to the calves other than a reduction in isoflurane requirement.