Intravenous Versus Perineural Ondansetron as an Adjuvant in Autonomic Neural Blockade for Laparoscopic Sleeve Gastrectomy: A Two-Center, Randomized, Double-Blind, Non-inferiority Trial

Obesity and its associated disorders have significant implications for health, resulting in heightened productivity loss and reduced life expectancy while also negatively impacting the quality of life of patients. Surgical intervention is the most effective way to achieve sustainable weight loss in patients with obesity and to alleviate the associated comorbidities. Despite the current availability of minimally invasive bariatric surgical treatments, postoperative pain remains a significant issue. Vagal and sympathetic afferent signals originating from the gastrointestinal system stimulate the vomiting center, causing nausea and vomiting. Paragastric autonomic neural blockade (PANB) is a new method performed by injecting local anesthetic material into three to four separate points along the border between the lesser omentum and the stomach (from the esophagogastric junction to the distal antrum), the hepatoduodenal ligament, and the area covering the left gastric artery. This procedure aims to prevent visceral pain and symptoms of nausea and vomiting. Ondansetron is a serotonin receptor (5-HT3) antagonist used commonly to manage postoperative nausea and vomiting (PONV) through intravenous (IV) injection. It also has a local anesthetic effect and many studies used it as adjuvant in various regional anesthetic techniques. In this study, investigators will compare the combined antiemetic analgesic effects of IV and perineural (adjuvant to the local anesthetic bupivacaine in PANB) ondansetron. The investigators hypothesized that perineural administration of ondansetron will be non-inferior to the IV route regarding prophylaxis against PONV, and will provide superior postoperative analgesic effects by its local anesthetic enhancing action.