Apparatus and method for non-invasively determining oxygen saturation of venous blood and cardiac output using NIRS

An apparatus for determining a venous oxygen saturation value (SvO2) of a subject, comprising:

• a plurality of NIRS oximeter sensors, each operable to selectively emit light at one or more predetermined wavelengths into an independent tissue region, and sensing light traveling through the tissue region at the predetermined wavelengths, and produce sensed light signals representative of the sensed light;
• a processor in communication with the NIRS oximeter sensors, which processor is adapted to determine a tissue oxygen saturation value (StO2) for each region using the sensed light signals from the respective tissue region, and which processor is further adapted to assign a coefficient to each region, each of which coefficients reflects a portion of the StO2 value for the region attributable to venous blood, and which processor is further adapted to determine a SvO2 value for the subject using the StO2 region values and the respective coefficients.