Drugs for preventing postoperative nausea and vomiting in adults after general anaesthesia: a network meta-analysis

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: 1. To compare the efficacy and safety of different prophylactic pharmacological interventions (antiemetic drugs) either against no treatment, placebo or against each other (as mono- or combination prophylaxis) for the prevention of postoperative nausea and vomiting in adults undergoing any type of surgery under general anaesthesia. 2. To explore the best dose or dose range of the antiemetic drugs in terms of efficacy and safety. 3. To generate a clinically useful ranking of antiemetic drugs (mono- and combination prophylaxis) according to efficacy and safety.