S-ketamine Infusion on Chronic Postoperative Pain Following Breast Cancer Surgery: A Randomized Double-Blind Placebo-Controlled Trial

Chronic postoperative surgical pain (CPSP) is a frequent complication following breast surgery and poses a challenge in terms of treatment. We hypothesized that the incidence of CPSP would be reduced at 3 months post-breast surgery with the administration of S-ketamine compared to a placebo.

Participants were recruited and randomly assigned to either the S-ketamine group (S) or the control group (C). In group S, S-ketamine was administered as a 1.5 mg kg^-1 bolus followed by 2 mg kg^-1h^-1 infusion, while in group C, a placebo of 0.9% saline was administered in the same volume and rate as S-ketamine. The primary outcome was the incidence of CPSP, measured using a 0-10 numeric rating scale (NRS), at 3 months postsurgery.

A total of 72 patients scheduled for mastectomy were enrolled (group S, n = 33; group C, n = 32). The incidence of CPSP at 3 months postsurgery was significantly lower in group S compared to group C (18.2% vs. 48.3%, P < .05). There was no statistical difference between the 2 groups in terms of the incidence of moderate to severe pain. NRS scores for postoperative pain at rest and during movement were significantly lower at 4 h and 24 h post-surgery (P < .05, respectively). Patients in Group S had lower Patient Health Questionnaire-9 (PHQ-9) scores at one week and 3 months post-surgery compared to Group C (P < .05, respectively).

S-ketamine infusion reduces the incidence of CPSP 3 months after breast surgery.