Effects of subanesthesia dose S‐ketamine induction on postoperative psychiatric complications after gynecological surgery

Ketamine may become an important drug for multimodal analgesia regime again because of its strong analgesic effects and retaining the advantage of spontaneous breathing. The present study was designed to explore the influences of different dosages of S‐ketamine anesthesia induction regimes on psychiatric complications and postoperative prognosis in patients undergoing gynecological operations. In this prospective, triple‐blinded, randomized, controlled study, patients undergoing elective gynecological surgery were randomized to one of three treatment groups: low‐dose S‐ketamine (LDSK) group (a 0.3 mg/kg bolus for anesthesia induction), minimal‐dose S‐ketamine (MDSK) group (a 0.2 mg/kg bolus for anesthesia induction), and placebo (CON) group (a saline bolus for anesthesia induction). The main outcome measures were as follows: intraoperative vital signs, extubation time, anesthesia recovery time and postanesthesia care unit (PACU) stay duration, incidence of psychiatric complications, Ramsay sedation scale (RSS) 1, 2, 24, and 48 h, postoperatively, and overall prognosis. One hundred and eighty female participants were finally included in this study from April 2021 to December 2021. Significant differences were not observed in age, height, weight, American Society of Anesthesiologists physical status classification, or history of mental illness between the groups. No statistically significant differences were discovered with regard to intraoperative vital signs, extubation time and PACU stay duration, incidence of psychiatric complications, and RSS scores at 1, 2, 24, and 48 h postoperatively in the three groups. However, the visual analog scale (VAS) scores of the CON group at 10 min after extubation and at the time point leaving PACU were much higher than that of the LDSK and MDSK groups. The VAS scores at 48 h after surgery in the MDSK group were also lower than that of the CON group and the CON group had received more analgesic drug treatment in the surgical wards consequently. Postoperative nausea and vomiting (PONV) occurrence at 24 and 48 h, postoperatively, increased sharply in the CON group than in the other two experimental groups, which led to an increase in the use of postoperative antiemetic drugs in this group. According to the postoperative satisfaction survey, patients in the CON group had lower medical satisfaction. Our data demonstrate that a small dosage of S‐ketamine anesthesia induction can reduce postoperative pain and the incidence of PONV without increasing hemodynamic fluctuations or psychiatric complications.