“…Outcomes analyzed were postoperative pain (pain scores after leaving the operation room) [2]–[5], [8]–[23], postoperative (24 hours) analgesic requirements (either doses or percentage of patient receiving postoperative opioids or nonopioids analgesics)[2]–[4], [8]–[10], [12]–[14], [16], [19], [20], [22]–[25], time to first analgesic administration (opioid or nonopioid analgesics administered with a defined pain intensity target)[3]–[5], [8]–[10], [12]–[14], [18], [22], [23], [26], time to first oral uptake [2], [5], [13], [14], postoperative nausea and vomiting (percentage of patients or dose of antiemetics) [2], [8], [9], [12]–[18], [24], [25] and the occurrence of psycho-mimetic manifestations including nightmares [9], [10], [18], sleep pattern change (percentage of patients) [9], [10], [12], [19], hallucinations (percentage of patients) [5], [8], [18], [19], [25] or sedation (sedation scores) [4], [5], [8], [9], [11], [15], [17], [24]. These outcomes were compared with preoperative ketamine ...…”