System and Method of Measuring Venous Oxygen Saturation Using Intelligent Pulse Averaging With Integrated EKG and PPG Sensors

A system for determining venous oxygen saturation, comprising:

• (a) a device positionable against a person's skin;
• (b) at least one PPG sensor mounted on the device for measuring the person's PPG signal at multiple wavelengths of light;
• (c) a plurality of electrodes for measuring the person's EKG signal;
• (d) a computer logic system for receiving and analyzing the PPG signal and the EKG signal, wherein the computer logic system further comprises:
• (i) a system for identifying cardiac cycles in the EKG signal;
• (ii) a system for segmenting the PPG signal into a series of PPG signal segments based upon features in the identified cardiac cycles,
• (iii) a system for sorting the PPG signal segments into a plurality of bins, each bin based upon durations of prior R-to-R cardiac cycles and current R-to-R cardiac cycles,
• (iv) a system for generating a composite signal for each of the plurality of bins, and
• (v) a system for measuring a person's venous oxygen saturation by:
• (a) calculating arterial oxygen saturation by comparing composite signals measured at different wavelengths of light,
• (b) sub-sampling composite signals at two consecutive signal maxima measured at different wavelengths of light, and
• (c) comparing the sub-sampled composite signals measured at different wavelengths of light to the calculated arterial oxygen saturation to determine venous oxygen saturation.