The effect of low dose ketamine on postoperative quality of recovery in patients undergoing breast cancer surgery: a randomized, placebo controlled trial

Abstract Background: Intraoperative low dose ketamine has been widely studied for postoperative multimodal analgesia. However, the effect of low dose ketamine on postoperative quality of recovery in female patients undergoing breast cancer surgery has not been studied. The primary aim of this study was to assess the effects of low dose ketamine on postoperative quality of recovery in these patients using the 40-Item Quality of Recovery (QoR-40) scale. The second aim of this study was to evaluate the effects of intraoperative infusion of low-dose ketamine on chronic postoperative surgical pain (CPSP). Methods: In this prospective, randomized, double-blind trial, 100 patients planned for modified radial mastectomy were randomly assigned to one of two groups: control group (group C) and ketamine group (group K). After induction of anesthesia and before surgical incision, a bolus dose of 0.5 mg/kg ketamine or an equivalent volume of normal saline was injected followed by 0.25 mg/kg/h ketamine or normal saline infusions until skin closure. Postoperative recovery profiles, including the QoR-40 scores on postoperative day 1, numeric rating scale (NRS), and douleur neuropathique 4 (DN-4) questionnaire at postoperative month 3 were evaluated. In addition, patient characteristics, perioperative parameters, and safety outcomes were assessed. Results: Global QoR-40 scores on postoperative day 1 were not significantly different between both groups (p = 0.139). Of the five dimensions, emotional state and pain scores were significantly higher in group K than in group C (p = 0.044 and 0.023, respectively). At postoperative month 3, CPSP and neuropathic pain (NP) were not significantly different between groups (p = 0.259 and 0.959, respectively). The incidence of safety outcomes were similar between groups. Conclusion: Low dose ketamine did not improve overall quality of recovery or chronic pain in patients undergoing breast cancer surgery.