Thrifty effect of subanesthetic-dose S-ketamine on postoperative opioids and its safety and analgesic effectiveness: A prospective, triple-blind, randomized controlled, polycentric clinical trial.

Aim: To investigate the thrifty effects of subanesthetic-dose S-ketamine on postoperative opioids and its safety and analgesic efficacy.

Methods: Four-hundred and twenty patients were divided into the control group (CON group), the S-ketamine 0.2 mg/kg group (ES0.2 group), and the S-ketamine 0.3 mg/kg group (ES0.3 group) randomly. Major indicators include the Visual Analogue Scale (VAS), the times of compression with analgesic pumps after surgery, and analgesic drug consumption from anesthesia induction to 48 h after surgery. Minor records include vital signs, the use of vasoactive drugs, the Ramsay scores, the occurrence of adverse events including nervous system reaction, and the patient's satisfaction with anesthesia.

Results: Compared with the CON group, VAS scores decreased in the ES0.2 and ES0.3 groups ( < 0.05). At 10 min after extubation, the VAS scores of the ES0.3 group were lower than that of the ES0.2 group ( < 0.05). The total number of compression with analgesic pumps of the ES0.3 group was lower than that of the CON group ( < 0.05). The opioid consumption after surgery of the ES0.3 group was lower than those of the CON group and the ES0.2 group ( < 0.05). The ES0.3 group's heart rate (HR) was faster but the use of vasoactive, drug consumption was less than the other two groups ( < 0.05). There were no significant differences in the incidence of postoperative adverse events and anesthetic satisfaction among the three groups.

Conclusion: Subanesthetic-dose S-ketamine at 0.2-0.3 mg/kg especially the 0.3 mg/kg in general anesthesia induction can safely and effectively reduce postoperative pain and save postoperative opioid consumption.