Inclusion Criteria:  Patients between 45 and 75 years old who undergo surgery of coronary bypass with CPB, univalvular replacement, bivalvular or coronary bypass plus univalvular on a scheduled basis at the UC-Christus Clinical Hospital (HCUC) and that have ASA II-III classification.  Exclusion Criteria:  BMI> 35, history of chronic liver damage, kidney damage with estimated creatinine clearance <60 ml / min, severe ventricular dysfunction (EF <30% or severe dysfunction in ventriculography), recent cerebrovascular accident (CVA) or sequelae, endocarditis, use of intraoperative ultrafiltration or methadone in the previous 36 hours.