Inclusion Criteria:  Female patients, aged between 18 and 70 years, electively scheduled for mastectomy at Hospital Regional de Sobradinho and Hospital de Base do Distrito Federal; American Society of Anesthesiology (ASA) physical status I, II or III  Exclusion Criteria:  Patient with severe heart disease; Patient with severe liver disease; Patient with severe kidney disease; Patient with a neurological disease; Use of psychoactive drugs; Pregnant women; Patients with allergies to any medication used in the study; Patients with chronic pain; Patients who refused to participate in the study.