Objective and Aims: The pig is a human translational model with increasing use and significance in research. Analgesic protocols for pigs are often limited by technical challenges of administration, lack of trained overnight staff, and lack of dosage validation. Locoregional anesthesia is a potential solution to these problems, as well as a proposed strategy for overall opioid consumption reduction. The TAP block is a locoregional anesthesia technique routinely used in human and veterinary medicine to provide analgesia to the abdominal wall for laparotomies and other abdominal procedures. This study aims to evaluate the quality and duration of liposomal bupivacaine’s ability to reduce nociception in pigs undergoing abdominal surgical procedures, by comparing a liposome encapsulated, slow release preparation of a local anesthetic (bupivacaine) with a plain formulation (bupivacaine HCl). A group with a more conventional analgesic approach using systemic opioids (buprenorphine) and current standard of care, will serve as control.

Experimental Design and Methods: Pigs will be randomly assigned to three groups: TAP block with a liposome encapsulated bupivacaine formulation (NOCI), TAP block with bupivacaine Hcl (BUPI), or a control group with systemic opioids, buprenorphine (BUPRE). Duration and overall quality of the block will be assessed primarily via abdominal wall sensory function. Pain scores, opioid consumption, return to normal behavior (eating, drinking, urinating, defecating) will be compared as well, understanding that the study is powered based on the data available for sensory duration, and may not be sufficient to find statistical significance for this additional data of interest. Linear mixed models will be run for each continuous variable (sensory score, analgesia scores) with the fixed effects of treatment, time, and the interaction of treatment and time. “Time to” variables will be evaluated with survival analysis and the Mantel-Cox test.