During pediatric cardiac surgery up to 4 arterial blood samples may be obtained from a routinely placed indwelling arterial cannula (baseline, before initiating cardiopulmonary bypass (CPB), during CPB, and after CPB). Typically most cases involve 2-3 samples per subject. Depending on the complexity of the case a greater number of blood samples may be obtained for example when a second CPB run becomes necessary or if there is hemodynamic or respiratory instability during the period following CPB. Each of these blood gas samples is analyzed by a blood gas analyzer (radiometer). Amongst many variables the hemoglobin concentration in the blood and the oxygen saturation of the hemoglobin molecule is given. This reading can be compared to the investigational and reference pulse oximeter readings at the time the blood sample was drawn. The number of probes tested depends on how many oximeters the sponsor will provide and their design.

The study oximeter probe readings will be recorded on an Excel spreadsheet by a clinical research coordinator. When the data from the blood gas analyzer becomes available it will also be recorded. At the end of the procedure, the research nurse or the investigator will check for pressure injuries and burns from the pulse oximeter. The devices will not be kept on overnight or when either the PI or Co-PI are not on campus. Convenience sample data will only be recorded by the PI or co-PI in the CICU and OR. The PI or co-PI record the sample values if possible. If the Co- PI or PI is not available to record the data, the blood sample will be drawn and the no data will be recorded. All data collection in the CICU will stop 24 hours after the completion of surgery.