Abstract / Summary
Administration of lidocaine at acupuncture points has been shown to reduce analgesic requirements and cytokine levels in human surgical patients. This study aimed to compare the effect of lidocaine pharmacopuncture and lidocaine constant rate infusion (CRI) on perioperative analgesia and serum interleukin levels in bitches undergoing ovariohysterectomy. Following methadone (0.3 mg/kg IM) administration, anesthesia was induced with propofol intravenously dosed to effect and maintained with isoflurane. After intubation, 27 dogs were randomly assigned ( n = 9 per group) to receive lidocaine (1 mg/kg) at the Stomach 36 and Spleen 6 acupoints (LAP group), lidocaine CRI (2 mg/kg; 50 µg/kg/min; LIV group), or saline CRI (2 mL/kg; 2 mL/kg/min; SAL group). Intraoperatively, cardiopulmonary variables, anesthetic and analgesic requirements were monitored. Fentanyl (2.5 µg/kg) was given to control cardiovascular responses to surgical stimulation. Sedation and pain were assessed preoperatively and at predetermined time points up to 24 h post-extubation using sedation scoring and the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF). Methadone (0.3 mg/kg, IM) was administered as rescue analgesia when the CMPS-SF score was ≥ 6/24 or ≥ 5/20 when mobility could not be assessed. Serum interleukin (IL-6 and IL-10) concentrations were measured preoperatively and 24 h post-surgery. Data were analyzed using Fisher’s exact test, Wilcoxon and Friedman tests ( p < 0.05). Cardiopulmonary variables, isoflurane requirements, interleukin levels, pain, and sedation scores did not differ among groups, while perioperative analgesic requirements were lower in the LAP than in SAL group ( p = 0.049). Analgesic intervention was required in 1/9 dogs in the LAP group (fentanyl and methadone, n = 1), 5/9 in the LIV group (fentanyl and methadone, n = 3; methadone, n = 2), and 6/9 in the SAL group (fentanyl, n = 3; fentanyl and methadone, n = 1; methadone, n = 2). Compared with baseline, IL-6 decreased postoperatively only in the LAP group ( p = 0.031). Lidocaine pharmacopuncture resulted in lower analgesic requirements than other treatments, with a significant difference only compared with saline CRI, and was associated with lower IL-6 levels 24 h after surgery than preoperative values.