Efficacy of Ketamine for Opioid-Free Anesthesia (OFA) in Patients Undergoing Mastectomy: A Randomized Controlled...

Opioid-free anesthesia (OFA) is an emerging practice in cancer care, providing adequate analgesia with reduced side effects. The objective of the study is to evaluate whether ketamine can replace morphine for performing OFA by assessing the acute pain relief achieved and to evaluate its effect on chronic pain.

A total of 182 women undergoing modified radical mastectomy were recruited and randomized into the morphine group and the ketamine group. Participants in the morphine group received 0.05 mg/kg morphine 20 minutes before induction, and those in the ketamine group received 0.40 mg/kg bolus and 1.00 mg/kg/hour ketamine infusion until axillary dissection. The numerical rating pain scale (NRS) at 0, 2, 6, 12, and 24 hours postsurgery was recorded, and the Revised American Pain Society Patient Outcome Questionnaire (APS-POQ-R) was filled out the next day. The chronic pain score at 3 and 6 months after surgery was noted.

The mean NRS at 24 hours was 2.385 ± 0.965 in the ketamine group and 2.240 ± 0.996 in the morphine group (P = 0.336). The APS-POQ-R showed that, on average, patients in the ketamine group and the morphine group experienced moderate to severe pain for and 28.00% and 27.72% of the time in a day, respectively, and rescue analgesia usage was also comparable. The incidence of chronic pain was 28.9% and 21.2% (P = 0.31) at 3 months and 32.1% and 21.2 % (P = 0.19) at 6 months in the ketamine group and the morphine group, respectively, and not statistically significant.

The results demonstrated that both ketamine and morphine provided similar levels of acute pain relief during the procedure, with no significant difference in pain outcomes between the two groups. These findings suggest that ketamine may be a viable alternative to morphine in the management of pain during OFA, with similar efficacy in both acute and chronic pain relief.