The Fore-Sight(TM) is a non-invasive monitor for brain tissue oxygenation (SctO2), by projecting harmless near-infrared light trough the skin, skull, and brain via a disposable sensor that is applied on the forehead of patients. In many centres, the Fore-Sight (TM) is part of the routine monitoring of children during cardio-pulmonary bypass for congenital heart surgery. Although the monitor has not been tested for this purpose, it is often continued in the postoperative phase in the intensive care unit (ICU), where it is used to monitor the hemodynamic situation of the patient.