The present trial is to study the effect of low dose remimazolam on postoperative nausea and vomiting (PONV) in patients at risks of PONV (women, postoperative use of opioid, nonsmokers) undergoing laparoscopic cholecystectomy.

Postoperative nausea and vomiting (PONV) is a common complication in patients undergoing general anesthesia. It is reported that PONV is observed in 50% of patients 24 hours after general anesthesia and upto 80% in high risk patients. The patients experiencing PONV may experience severe discomfort that it is important to prevent PONV. There are several prophylactic agents for PONV. 5 serotonin receptor antagonist(5-HT3 antagonist) is the most commonly used agent and other agents such as corticosteroid, neurokinin-1 receptor antagonist can also be used. Previous studies have reported the efficacy of benzodiazepine(midazolam) in a low targeting dose as a prophylactic agent of PONV. The efficacy of low dose remimazolam (short acting benzodiazepine) on PONV has not been evaluated.

According to Fourth consensus guideline for the management of postoperative nausea and vomiting (2020), three prophylactic anti-emetics are recommended for patients with three or more of the risk factors of PONV. As the patients included in our study have three or more of risk factors of PONV (women, postoperative use of opioid, nonsmokers), three prophylactic anti-emetics are recommended. Our center has routinely been using 5-HT3 receptor antagonist (ramosetron) and corticosteroid (dexamethasone) for women undergoing laparoscopic cholecystectomy. However, we still find many patients complaining nausea and vomiting after operation. Therefore, we are willing to investigate the low supplemental dose of remimazolam on the prophylaxis of PONV.

Inclusion Criteria:

• women undergoing laparoscopic cholecystectomy under general anesthesia.

Exclusion Criteria:

• moderate to severe liver dysfunction (total bilirubin ≧ 3.0 mg/dL / aspartate aminotransferase(AST) or alanine aminotransferase(ALT) ≧ 2.5 times more than normal range)
• moderate to severe renal dysfunction (serum creatinine ≧ 2.0 mg/dL / end-stage renal disease undergoing hemodialysis)
• tolerance to benzodiazepines
• hypersensitivity to anesthetic drugs (Benzodiazepines, Propofol, Remifentanil, Fentanyl citrate, Rocuronium bromide, Flumazenil)
• acute angle glaucoma
• alcohol dependence
• Galactose intolerance, Lactase deficiency, glucose-galactose malabsorption
• pregnant, breast feeding women
• BMI >35 kg/m2
• uncontrolled diabetes mellitus