Analgesic and anti-inflammatory effects of lidocaine in dogs receiving fentanyl and undergoing thoracolumbar hemilaminectomy for intervertebral disc extrusion.

OBJECTIVE

To evaluate the effects of intraoperative intravenous lidocaine continuous rate infusion (CRI) on postoperative pain and interleukin-6 (IL-6) concentrations in dogs undergoing thoracolumbar hemilaminectomy for intervertebral disc extrusion.

STUDY

DESIGN

Prospective, randomized, blinded, controlled clinical trial.

ANIMALS: A group of 40 client-owned dogs.

METHODS

Dogs were anesthetized with a standardized protocol that included fentanyl CRI for intra- and postoperative analgesia. Dogs received either lidocaine CRI at 100 μg kg-1 minute-1 or NaCl 0.9% (control) intraoperatively. Pain was assessed at presentation, 0, 2, 6, 12, and 24 hours postanesthesia using the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF). IL-6 plasma concentrations were measured on presentation, 0, 6, and 48 hours postanesthesia. A generalized linear mixed model was used to compare IL-6 and end-tidal isoflurane concentration values between groups and over time. A binary mixed model was used to model rescue analgesic required over time and between groups. Wilcoxon rank sum tests were used to compare recovery scores, total hospitalized days, maximum dose of fentanyl used postoperatively, and CMPS-SF scores between groups. Spearman's correlation coefficient was used to assess correlation between IL-6 and CMPS-SF scores. Data are median (interquartile range).

RESULTS

Lidocaine was associated with lower pain scores (1, 1-6) compared to control (2, 1-11) at 0 hours (p = 0.023) with no significant differences between groups at other times. Lidocaine resulted in a lower anesthesia recovery score (1, 0-2) compared to control group (2, 1-3) (p = 0.041). IL-6 concentrations increased over time for both groups (p < 0.0001), with no significant differences between groups and no correlation between IL-6 values and postoperative pain scores.

CONCLUSIONS AND CLINICAL RELEVANCE: Intraoperative lidocaine CRI was associated with a lower CMPS-SF score during the immediate postoperative period, provided smoother anesthesia recoveries, and may be considered for dogs undergoing thoracolumbar hemilaminectomy.