Inclusion Criteria:  Patients undergoing radical mastectomy for pathology "breast cancer" Patient undergoing anesthetic technique due to erector spinae plane block Informed consent to perform the anesthesia technique. Karnofsky> 80 points  Exclusion Criteria:  Emergency surgery Patient with mental pathology that prevents pain assessment. Rejection of anesthetic technique. Patient with allergy to local anesthetics Patient with local infection of the puncture site for application of the erector spinae block