Because the brain is very sensitive to changes in oxygenation, monitoring of SctO2 might provide an indication of critical changes in the hemodynamic state of the patient, and thus serve as a monitor for the general hemodynamic status of the patient. The present study wishes to examine the added value of SctO2 monitoring over the routine monitoring of pediatric patients in PICU, in the postoperative phase after cardiac surgery. Ideally, in order to be of added value, SctO2 changes should precede an episode of hemodynamic deteriorations.