Figure 1. Near-infrared spectroscopy (NIRS) record of the changes in cerebrovascular hemoglobin oxygen saturation (Delta Sc^O2) illustrating the points at which Delta Sc^O2was captured and the deoxygenation curve during circulatory arrest. The patient was aged 9 months undergoing a hemi-Fontan operation. B = baseline at normothermia; 1 = on deep hypothermic cardiopulmonary bypass (cCPB); 2 = at the end of circulatory arrest (arrest); 3 = on recirculation 3 min after resuming CPB (rCPB); 4 = normothermic CPB (wCPB); 5 = after CPB (end). By definition, Delta Sc^O2= 0 at baseline.