Optimizing the Use of Ketamine to Reduce Chronic Postsurgical Pain

This is a phase 3, multicenter, randomized, double-blind, placebo-controlled trial to study the effectiveness of ketamine in reducing PMPS. In a 3-arm, parallel-group study, approximately 750 adult women undergoing mastectomy or prophylactic mastectomy for oncologic reasons will be randomized to one of three arms. Participants in the first arm will receive continuous ketamine infusion starting after anesthetic induction (0.35 mg/kg dose after induction, followed by a 0.25 mg/kg/hr infusion during surgery (with a maximum infusion of 6 hours) plus a postoperative saline dose, and continuation of 0.25 mg/kg/hr ketamine infusion for 2 hours postoperatively). Participants in the second arm will receive a dose of saline after induction, followed by a saline infusion during the surgery plus a single dose of 0.6 mg/kg of ketamine in the PACU, and 2 hours of saline infusion after surgery. The final group will serve as the control group and receive an intraoperative dose of saline, followed by saline infusion plus a postoperative saline dose and 2 hours of saline infusion after surgery. Participants will be followed at 1 and 7 days and 1, 3, 6, and 12 months after surgery.