Use of Transversus Abdominis Plane and Intercostal Blocks in Bitches Undergoing Laparoscopic Ovariectomy: A Randomized Controlled Trial

Abstract

In humans and dogs, loco-regional anesthesia is associated with lower peri-operative opioid consumption and less related side effects. The combination of transversus abdominis plane (TAP) and intercostal blocks can be used to desensitize the entire abdominal wall in dogs. The aim of this study was to evaluate the effectiveness of TAP and intercostal blocks in bitches undergoing laparoscopic ovariectomy. Twenty client-owned bitches were enrolled in this double-blinded randomized controlled trial. After premedication with dexmedetomidine, methadone and ketamine, the animals were randomized into two groups. Dogs in the TAP group received intercostal blocks from T8 to T10 and a TAP block with ropivacaine. Dogs in the FEN group received a fentanyl bolus and a constant rate infusion for the entire duration of the procedure. Intra-operative cardiovascular stability, post-operative pain scores, rescue opioid requirement, dysphoria during recovery, time to attain sternal recumbency and interest in food at 6 h post-extubation were compared. Bitches in the TAP group received a statistically significant lower amount of rescue fentanyl intra-operatively and methadone post-operatively. Pain scores were lower in the TAP group until 6 h post-extubation. No difference was found for dysphoric recoveries, time to attain sternal recumbency and appetite at 6 h post-extubation. No adverse event was recorded for any of the dogs. The combination of TAP and intercostal blocks can be part of an effective multi-modal analgesic strategy in bitches undergoing laparoscopic ovariectomy.

Evaluation of the Two-Point Ultrasound-Guided Transversus Abdominis Plane Block for Laparoscopic Canine Ovariectomy

“…The present study demonstrated that the combination of the TAP block with inhalational anesthesia significantly reduced the requirements of isoflurane needed to maintain the anesthetic plane suitable to perform the LapOV. This result contradicts one finding of the only study on TAP for LapOV, which did not find any difference in the median EtISO with their control group [ 19 ]. However, both studies show substantial differences in their design.…”

“…However, both studies show substantial differences in their design. For instance, while the TAP and control groups in the present study differ only in the TAP block, the comparison group in the study of Paolini et al received a fentanyl-loading dose, followed by a constant rate infusion during the inhalation anesthesia [ 19 ]. The difference in the anesthetic protocol between the groups might have biased the results, as the authors themselves noted [ 19 ].…”

“…However, that was a single, non-comparative study including only three dogs [ 24 ]. The study on TAP for LapOV previously mentioned speculates that the blocks may have resulted in some degree of visceral analgesia [ 19 ]. On the contrary, a recent study assessing the analgesic efficacy of the TAP for canine ovariectomy did not observe any difference in the intraoperative variables measured between the group of dogs with TAP and the control group, supporting the hypothesis of the ineffectiveness of the TAP in blocking the visceral nociceptive stimulation [ 18 ].…”

“…On the contrary, a recent study assessing the analgesic efficacy of the TAP for canine ovariectomy did not observe any difference in the intraoperative variables measured between the group of dogs with TAP and the control group, supporting the hypothesis of the ineffectiveness of the TAP in blocking the visceral nociceptive stimulation [ 18 ]. Furthermore, the effectivity of the TAP block to desensitize the abdominal skin, subcutaneous tissues, abdominal muscles, and underlying peritoneum is demonstrated [ 7 , 10 , 19 ]. Thus, the painful stimuli due to stretching the peritoneal tissues and the abdominal wall and the peritoneal irritation after the CO 2 insufflation could result in alleviation.…”

“…In human medicine, the TAP block has been used successfully for pain relief in a wide variety of laparoscopic procedures [ 12 , 13 , 14 , 15 , 16 ]. Although the studies are less widespread in veterinary medicine, single-injection TAP blocks for conventional [ 17 , 18 ] and laparoscopic ovariectomy (LapOV) [ 19 ] in dogs have been recently reported. Different ultrasound (US)-guided TAP block approaches have been described in canine cadavers [ 5 , 10 , 20 , 21 ].…”