The Effect of Ketamine on Acute and Chronic Wound Pain in Patients Undergoing Breast Surgery: A Meta‐Analysis and Systematic Review

Introduction Perioperative use of ketamine has been discussed widely in many kinds of surgery. The aim of our study was to evaluate the short‐term and long‐term benefits and safety of ketamine after breast surgery. Method We performed a quantitative systematic review. We included randomized controlled trials that compared intravenous administration of ketamine to a placebo control group, or compared bupivacaine in combination with ketamine to bupivacaine alone in thoracic paravertebral blocks or pectoral blocks among patients undergoing breast surgery. The primary outcome was postoperative pain intensity. Secondary outcomes included cumulative opioid consumption during the 0‐ to 24‐hour postoperative period, the effect on postmastectomy pain syndrome, the effect on postoperative depression, and the adverse events associated with the use of ketamine. Results Thirteen randomized controlled trials with 1,182 patients were included for analysis. Compared with placebo, intravenous ketamine was effective in reducing wound pain intensity during the first 6 hours after surgery (weighted mean difference [WMD] −0.83; 95% confidence interval [CI] −1.65, −0.01; P = 0.048) and during the first 24 hours after surgery (WMD −0.65; 95% CI −0.95, −0.35; P