A Method to Calculate Arterial and Venous Saturation from Near Infrared Spectroscopy (Nirs)

For adequate development and functioning of the neonatal brain, sufficient oxygen (O2) should be available. With a fast sampling (fs ≫ 50 Hz) continuous wave NIRS device, arterial (SaO2) and venous (SvO2) saturation can be measured using the physiological fluctuations in the oxyhemoglobin (O2Hb) and total hemoglobin (tHb) concentrations due to heart action and respiration. Before using this technique in a neonatal setting, the method was verified on adult volunteers (n=7) by decreasing inspired oxygen down to an arterial saturation of 70% using a pulse oximeter as reference. NIRS optodes were placed on the left forehead; the pulse oximeter sensor was placed on the right forehead. The experiments were repeated with different optode spacings.