High Risk surgical patients scheduled for elective abdominal extensive surgery were eligible. After enrollment, the patients were randomized to one of the two groups of treatment (A or B) by a phone system on a 24-hour-a-day, 7-day-a-week basis. Randomization was based on a permuted-block algorithm, allowing stratification for each center. The exclusion criteria from the study were : age below 16 years, preexistent neurologic, or malignant haematologic diseases.