This is an observational study. Cerebral and systemic oxymetry (rSO2) using near infrared spectroscopy (NIRS, Invos 5100; Somanet- ics Corporation, Troy, MI) will be performed on all patients with 4 optodes (right and left temporal area, arm and leg). Continuous rSO2 values will be stored on a hard disk with a 15 seconds update within intraoperative period and first 4 hours after the surgery. Desaturation phases (saturation decrease more than 20% of the basal value for more than 15 seconds) will be correlated to operative procedure or events. Postoperative adverse events will be collected. A correlation between desaturation and postoperative adverse events will be done with a multiple linear regression model.