Clinical comparison of two regimens of lidocaine infusion in horses undergoing laparotomy for colic.

This research compares the effects of administering or omitting a loading IV bolus of lidocaine prior to a steady infusion rate (CRI), in horses undergoing colic surgery. The study found that a preloading lidocaine bolus did not significantly influence the requirements of isoflurane, an anesthetic, nor did it substantially affect cardiopulmonary effects or recovery time compared to no preloading bolus.

Objective

Primarily, this study aimed to evaluate and compare the outcome of two different regimens of lidocaine infusion in horses during laparotomy for colic. The two methods varied in terms of whether a loading intravenous bolus was administered prior to constant rate infusion of lidocaine.

Methodology

• The study was a prospective, randomized clinical study involving thirty-six client-owned horses.
• Horses were randomly assigned to one of two groups: those receiving a loading bolus of lidocaine prior to the CRI (Group LB) and those which didn’t receive the loading bolus (Group L).
• Lidocaine infusion was initiated within 20 minutes of induction of general anesthesia and was discontinued roughly 30 minutes prior to the end of the surgical procedure.
• Various parameters such as anesthetic depth, end-tidal isoflurane concentration (Fe’ISO), intra-operative physiological values, and recovery quality were measured and compared between the two groups.
• Data were analysed using a set of statistical tests including one-way ANOVA, t-test, Fisher test, Wilcoxon, and Kruskal-Wallis tests.

Findings

• No significant difference was found in the mean end-tidal isoflurane concentration between the two groups.
• The heart rate was significantly higher in the non-loading bolus group at certain time points compared to the loading bolus group.
• No noticeable difference was observed between the two groups regarding other physiological values measured, nor in any measures taken to enhance these parameters.
• All horses, except for one pregnant horse in the non-loading group which fractured a femur during recovery, experienced comparable and satisfactory recovery phases.

Conclusion

The study concluded that a loading dose of lidocaine prior to constant rate infusion did not confer any significant advantage in horses undergoing laparotomy for colic. Particularly, it did not influence isoflurane requirements, show significant cardiopulmonary effects, or facilitate recovery compared to the non-loading bolus method.