Optimizing the Use of Ketamine to Reduce Chronic Postsurgical Pain

Inclusion Criteria: * Woman 18 years of age or older * Undergoing elective breast surgery for oncologic indication as follows: unilateral or bilateral mastectomy, prophylacticmastectomy, +/- lymph node dissection, +/- immediate or delayed reconstruction. * No distant metastases Exclusion Criteria: * History of cognitive impairment or clinical signs of altered mental status (AMS) that may interfere with adherence to study procedures and/or participant safety. Clinical signs of AMS may include but are not limited to: confusion, amnesia, disorientation, fluctuating levels of alertness, etc. * Past ketamine or phencyclidine misuse or abuse * Schizophrenia or history of psychosis * History of post-traumatic stress disorder * Known sensitivity or allergy to ketamine * Liver or renal insufficiency * History of uncontrolled hypertension, chest pain, cardiac arrhythmia, stroke, head trauma, intracranial mass or hemorrhage, glaucoma, porphyria, uncontrolled thyroid disease, or other contraindication to ketamine * Lamotrigine, alfentanil, physostigmine, or 4-aminopyridine use * Currently Pregnant * Body mass index (BMI) equal to or greater than 41 * Non-English or non-Spanish speaker * Currently participating in another pain interventional trial * Unwilling to comply with all study procedures and be available for the duration of the study * Patient is American Society of Anesthesiologists (ASA) physical status 4, 5, or 6 * Patient has started or undergone hormone therapy for gender transition into male. * Patient scheduled for any bilateral (or greater) flap reconstruction