This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To evaluate the efficacy and tolerability of ketamine administered intravenously during general anaesthesia or perioperatively for the treatment or prevention of acute postoperative pain in adult patients. We plan to carry out a subgroup analysis of studies in which postoperative hyperalgesia has been assessed and evaluate studies where nitrous oxide has been used as a component of general anaesthesia.