Clinical efficacy of an ultrasound-guided bilateral rectus sheath block for umbilical hernia repair in calves: A prospective randomized trial

Abstract

IntroductionSurgical umbilical hernia repair is a frequent procedure in newborn calves, requiring mandatory pain management. This study aimed to develop an ultrasound-guided rectus sheath block (RSB) and to evaluate its clinical efficacy in calves undergoing umbilical herniorrhaphy under general field anesthesia.MethodsGross and ultrasound anatomy of the ventral abdomen and the diffusion of a new methylene blue solution after injection within the rectus sheath were described in seven fresh calf cadavers. Then, fourteen calves undergoing elective herniorrhaphy were randomly assigned to receive either bilateral ultrasound-guided RSB with 0.3 mL/kg of bupivacaine 0.25% and 0.15 µg/kg of dexmedetomidine or 0.3 mL/kg of 0.9% NaCl (control). Intraoperative data included cardiopulmonary variables and anesthetic requirements. Postoperative data included pain scores, sedation scores and peri-incisional mechanical threshold assessed by force algometry at specific time points after anesthetic recovery. Treatments were compared using Wilcoxon rank-sum, Student's t-test, and Cox proportional hazard model as appropriate. Mixed effect linear models on rank, with random effect calf; fixed effects time, treatment, and their interaction were used to compare pain scores and mechanical thresholds over time. Significance was set at p = 0.05.Results and DiscussionCalves receiving RSB recorded lower pain scores between 45 – 120 minutes (p < 0.05) and at 240 min after recovery (p = 0.02). And they recorded higher mechanical thresholds between 45 and 120 min after surgery (p < 0.05). Ultrasound-guided RSB provided effective perioperative analgesia in calves undergoing herniorrhaphy under field conditions.

Use of subcostal and lateral transverse abdominal plane blocks as part of multimodal analgesia in a calf undergoing omphalitis surgical correction

“…Nevertheless, these calves reported lower postoperative pain and higher mechanical thresholds than the control group. 28 A 0.5 mL/kg injection volume provided better T8 to L2 ventral branch coverage, 24 similar to Mirra et al's results. 9 The authors opted to perform the subcostal and lateral USguided TAP block for the management of this case, as they were more familiar with the technique and there is a body of literature supporting the use of the TAP block across various species.…”

“…Indeed, calves undergoing umbilical hernia repair that received bilateral US‐guided rectus sheath block with bupivacaine 0.25% (0.3 mL/kg) and dexmedetomidine (0.15 μg/kg) needed repeated doses of ketamine and xylazine to maintain adequate anaesthesia plane. Nevertheless, these calves reported lower postoperative pain and higher mechanical thresholds than the control group 28 . A 0.5 mL/kg injection volume provided better T8 to L2 ventral branch coverage, 24 similar to Mirra et al.’s results 9 …”

“…In our case, a total volume of 0.7 mL/kg of lidocaine 2% was utilised, meaning that a dose of 14.2 mg/kg was administered locally. This dose exceeded the maximum safe dose reported in the literature, which ranged between 3, 28 6 23 and 10 mg/kg 30,32 in cattle, but the overall amount (60 mL) was still within the manufacturer's recommended dose for local infiltration (60–100 mL).…”

“…26 The rectus sheath block, a US-guided technique to provide analgesia for abdominal surgery, has been considered in cattle. 27,28 However, when compared to the combination of subcostal and lateral TAP blocks, it showed less coverage of the T8 to L2 ventral branches with a 0.25 mL/kg volume. Indeed, calves undergoing umbilical hernia repair that received bilateral US-guided rectus sheath block with bupivacaine 0.25% (0.3 mL/kg) and dexmedetomidine (0.15 μg/kg) needed repeated doses of ketamine and xylazine to maintain adequate anaesthesia plane.…”

“…The rectus sheath block, a US‐guided technique to provide analgesia for abdominal surgery, has been considered in cattle 27,28 . However, when compared to the combination of subcostal and lateral TAP blocks, it showed less coverage of the T8 to L2 ventral branches with a 0.25 mL/kg volume.…”