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US 11,896,405 B2Granted
System and method of measuring venous oxygen saturation using intelligent pulse averaging with integrated EKG and PPG sensors
AssigneeHemocept Inc.
InventorsEric Raman, Kevin Peterson, Iain Hueton
Life of this patent
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Abstract
A system using combined electrocardiography (EKG) and photoplethysmography (PPG) sensing, to determine venous oxygen saturation is described. The system uses averaging of similar pulses based on Prior (or n−1) R-to-R pulse wave duration, and current (or n) R-to-R pulse wave duration for evaluation of the metabolic reserve and/or stress of the patient.
Claims15
A system for determining venous oxygen saturation, comprising:
- (a) a device positionable against skin of a person;
- (b) at least one PPG sensor mounted on the device for measuring a PPG signal of the person at multiple wavelengths of light;
- (c) a plurality of electrodes for measuring an EKG signal of the person;
- (d) a computer logic system for receiving and analyzing the PPG signal and the EKG signal,
- wherein the computer logic is configured to:
- identify cardiac cycles in the EKG signal;
- segment the PPG signal into a series of PPG signal segments based upon features in the identified cardiac cycles,
- sort the PPG signal segments into a plurality of bins based upon a similarity in durations of prior R-to-R cardiac cycles and a similarity in durations of current R-to-R cardiac cycles,
- generate a composite signal for each of the plurality of bins,
- generate a composite Signal Prime Over Signal (SPOS) for each of the composite signals by calculating a derivative of the composite signal and normalizing the derivative of the composite signal by the composite signal itself,
- measure venous oxygen saturation of the person by:
- (a) calculating arterial oxygen saturation by comparing the composite SPOS 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 SPOS signals measured at different wavelengths of light to the calculated arterial oxygen saturation to determine venous oxygen saturation, and
- output to a display device an indication of the determined venous oxygen saturation to enable noninvasive monitoring of cardiac conditions.
12 more elements
A system for determining venous oxygen saturation, comprising:
- (a) a device positionable against skin of a person;
- (b) at least one PPG sensor mounted on the device for measuring a PPG signal of the person at multiple wavelengths of light;
- (c) a plurality of electrodes for measuring an EKG signal of the person;
- (d) a computer logic system for receiving and analyzing the PPG signal and the EKG signal,
- wherein the computer logic system is configured to:
- identify cardiac cycles in the EKG signal;
- segment the PPG signal into a series of PPG signal segments based upon features in the identified cardiac cycles,
- sort the PPG signal segments into a plurality of bins based upon a similarity in durations of prior R-to-R cardiac cycles and a similarity in durations of current R-to-R cardiac cycles,
- generate a composite signal for each of the plurality of bins by summing or averaging the PPG signal segments in the bin, and
- generate composite Signal Prime Over Signal (SPOS) for each of the composite signals by calculating a derivative of the composite signal and normalizing the derivative of the composite signal by the composite signal itself, and
- measure venous oxygen saturation of the person by:
- (a) calculating arterial oxygen saturation by comparing the composite SPOS 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.
11 more elements
A system for determining venous oxygen saturation, comprising:
- (a) a device positionable against skin of a person;
- (b) at least one PPG sensor mounted on the device for measuring a PPG signal of the person at multiple wavelengths of light;
- (c) a plurality of electrodes for measuring an EKG signal of the person;
- (d) a computer logic system for receiving and analyzing the PPG signal and the EKG signal,
- wherein the computer logic system is configured to:
- identify cardiac cycles in the EKG signal;
- segment the PPG signal into a series of PPG signal segments based upon features in the identified cardiac cycles,
- sort the PPG signal segments into a plurality of bins based upon a similarity in durations of prior R-to-R cardiac cycles and a similarity in durations of current R-to-R cardiac cycles,
- generate a composite signal for each of the plurality of bins comprising a system for removing aberrant PPG signal segments from the calculation of the composite signal by iteratively re-calculating the composite signal, by:
- comparing a SPOS of each of the PPG signal segments used to calculate a composite signal against the SPOS of the calculated composite signal,
- removing outlier PPG signal segments,
- re-calculating the composite signal with the outlier PPG signal segments removed, and
- repeating the iteration until there are no more outlier PPG signal segments, and measure 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.
13 more elements
Dependencies are inferred from the claim text.