Evaluation of the Analgesic Efficacy of Undiluted Intraperitoneal and Incisional Ropivacaine for Postoperative Analgesia in Dogs after Major Abdominal Surgery

Abstract

Recommendations for intraperitoneal (IP) and incisional (INC) administration of local anaesthetics after visceral surgery exist, but evidence is scarce. This prospective, randomized, blinded, controlled, clinical trial compared postoperative pain in dogs undergoing major abdominal surgery. Sixteen client-owned dogs were anaesthetized with a standardized balanced protocol including opioids and received either 2 mg/kg ropivacaine IP (0.27 mL/kg) and a 1 mg/kg INC splash (0.13 mL/kg) or equal volumes of saline. Influence of the treatment on heart rate (HR) and postoperative pain was assessed using the Short Form of the Glasgow Composite Pain Scale (GCPS-SF), a dynamic interactive visual analogue scale (DIVAS) and mechanical nociceptive threshold testing (MNT). Data was tested with mixed ordinal regression and log linear mixed models for 0.5, 1, 2, 3, 4, 6, 8, 10 and 12 h after extubation. Rescue analgesia was given to 3/8 dogs after ropivacaine and 0/8 dogs after saline. GCPS-SF and MNT were not different between groups. DIVAS was slightly higher after ropivacaine (odds increased by 5.44 (confidence interval (CI) 1.17-9.96, p = 0.012)), and HR after ropivacaine was 0.76 * that after saline (CI 0.61-0.96, p = 0.02) with no effect of time (p = 0.1). Undiluted ropivacaine IP and INC was not beneficial for postoperative analgesia.

Keywords: anaesthesia; analgesia; canine; companion animals; laparotomy; locoregional; pain; visceral surgery.

Figure 1

Visualised analgesic protocol and interventions for 16 dogs undergoing major abdominal surgery, and receiving either ropivacaine 2 mg/kg intraperitoneally and 1 mg/kg incisionally (group Ropivacaine), or an equal volume of isotonic saline (group Control), until extubation. Note that the distances on the chart are not true to real time scale. The green bar displays the part of the study the animal spent in the surgical theatre. IM = intramuscular, IV = intravenous, CRI = continuous rate infusion, IP = intraperitoneal, INC = incisional.

Figure 2

(a–c). Pain scores as attained with (a) the Short Form of the Glasgow Composite Pain Scale (GCPS-SF), (b) the dynamic interactive visual analogue scale (DIVAS), and (c) values for mechanical nociceptive threshold testing (MNT) of eight dogs in group Control and group Ropivacaine, respectively, represented as boxplots. The median and the upper (75%) and lower (25%) quartile are depicted with the box while the whiskers indicate the range. The dotted line in the GCPS-SF diagram represents the cutoff value at which rescue analgesia was administered.