Analgesic Efficacy of Bupivacaine or Bupivacaine-Dexmedetomidine After Intraperitoneal Administration in Cats: A Randomized, Blinded, Clinical Trial

Abstract

The aim of this study was to compare the analgesic efficacy of intraperitoneal bupivacaine vs. bupivacaine-dexmedetomidine in combination with intramuscular buprenorphine in cats undergoing ovariohysterectomy. Sixty healthy adult cats (2.8 ± 0.7 kg; n = 30/group) were included in a randomized, prospective, blinded, clinical trial after owners' written consent. After premedication with acepromazine (0.02 mg/kg) and buprenorphine (0.02 mg/kg) intramuscularly, anesthesia was induced with propofol to effect (6.2 ± 1.4 mg/kg) and maintained with isoflurane. Bupivacaine 0.25% alone (BG; 2 mg/kg) or bupivacaine (same dose) with dexmedetomidine (BDG; 1 μg/kg) were instilled/splashed over the ovarian pedicles and caudal aspect of uterus before ovariohysterectomy. Final injectate volume was standardized between groups. Sedation was evaluated using a five-point simple descriptive scale. Pain was evaluated using the short-form UNESP-Botucatu composite pain scale (SF-CPS) before, and at 0.5, 1, 2, 3, 4, 6, 8, 12, and 24 h after surgery. Rescue analgesia was provided with buprenorphine (0.02 mg/kg intravenously) and meloxicam (0.2 mg/kg subcutaneously) when SF-CPS ≥ 4. The Mantel-Haenszel chi-square test was used for analyzing ordinal variables (e.g., SF-CPS pain scores). The effect of time in SF-CPS scores was assessed with the Cochran-Mantel-Haenszel test for repeated measures. The alpha level for each contrast was adjusted downward with the sequential Benjamini-Hochberg procedure. The number of cats receiving rescue analgesia was analyzed using χ2 test (p < 0.05). The prevalence of rescue analgesia was the same for the two treatments (p = 1.000) [BG, n = 6, 20%; BDG, n = 6, 20%] and similar for timing of rescue analgesia (p = 0.16). The SF-CPS scores were significantly increased between 1 and 12 h in BG, and between 0.5 and 8 h in BDG when compared with baseline values. Median (interquartile range) pain scores were higher in BG [1 (1–2)] than BDG [1 (0–1)] at 12 h (p = 0.023). Sedation scores were not significantly different between groups throughout the study. In terms of prevalence of rescue analgesia, but not duration of action, the analgesic efficacy of bupivacaine-dexmedetomidine was similar to bupivacaine alone after intraperitoneal administration in cats receiving buprenorphine.

Peer Review #2 of "Clinical applicability of the Feline Grimace Scale: real-time versus image scoring and the influence of sedation and surgery (v0.1)"

“…Alternatively, the evaluation of the LOA in relation to the analgesic threshold has been 337 proposed ). The LOA observed in the present study, although narrow (LOA 338 final score : -0.351 to 0.237), spans the analgesic threshold of 0.39 out of 1.0 previously determined 339 for the FGS (Evangelista et al 2019). This would mean that FGS-RT scores that are close to the 340 analgesic threshold (slightly lower or higher than 0.39) should be interpreted with caution since 341 this threshold is a suggestion for the administration of rescue analgesia based on the probability 342 of being painful above that score.…”

Clinical applicability of the Feline Grimace Scale: real-time versus image scoring and the influence of sedation and surgery

“…Furthermore, the mean elimination half-life of bupivacaine was 4.8 ± 2.7 and 10.5 ± 10.3 h after intraperitoneal administration of bupivacaine alone and in combination with dexmedetomidine, respectively, in cats (Benito et al, 2016;Benito et al, 2018). Significant differences in pain or sedation scores, and the prevalence of rescue analgesia were not found between cats receiving intraperitoneal bupivacaine alone or in combination with dexmedetomidine (Benito et al, 2019). For this reason, the FGS scores considered in the present study were analyzed together.…”

“…Eighty-one adult female domestic cats from local shelters were admitted to the veterinary teaching hospital (Centre Hospitalier Universitaire Vétérinaire) of the Faculty of Veterinary Medicine, Université de Montréal for elective OVH between June and October 2018. The study was designed to evaluate the analgesic efficacy of intraperitoneal administration of bupivacaine alone or in combination with dexmedetomidine (Benito et al, 2019). The current study occurred in parallel to evaluate changes in the FGS.…”

“…Anesthetic and surgical procedures are described thoroughly elsewhere (Benito et al, 2019). In brief, food was withheld for 8-12 h before general anesthesia; cats were premedicated with acepromazine (0.02 mg/kg) and buprenorphine (0.02 mg/kg) intramuscularly; anesthesia was induced with propofol intravenously to allow endotracheal intubation (4-6 mg/kg) and maintained with isoflurane in oxygen.…”

Intraperitoneal and incisional analgesia in small animals: simple, cost‐effective techniques

“…These adjuvant drugs produced delayed absorption and a longer terminal half-life when compared with bupivacaine alone (Benito et al 2018). However, the prevalence of rescue analgesia was not significantly different between IP bupivacaine alone and bupivacaine in combination with dexmedetomidine in a clinical trial involving 60 cats undergoing ovariohysterectomy (Benito et al 2019). It appears that the use of such vasoactive drugs for IP analgesia is not supported by strong evidence at this time.…”