Inclusion Criteria:  Patients older than 18 years old Patients that are scheduled to major abdominal and thoracic elective surgery in Universtity Hospital Vall d´ Hebrón. Patients ASA I, II and III. Patients that after the intervention have their recovering in the Surgical ICU  Exclusion Criteria:  Patients ASA IV and V. Patients that are hospitilized previous to the surgery. Patients that undergo emergent surgery. Patients with Chronic or Acute Renal Failure previous to the surgery. Patients with past medical history of autoinmune disseases. Patients with an active infection previous to the surgery. Patients in treatment with steroids previous to the surgery