Active-pulse blood analysis system
An active-pulse blood analysis system has an optical sensor that illuminates a tissue site with multiple wavelengths of optical radiation and outputs sensor signals responsive to the optical radiation after attenuation by pulsatile blood flow within the tissue site. A monitor communicates with the sensor signals and is responsive to arterial pulses within a first bandwidth and active pulses within a second bandwidth so as to generate arterial pulse ratios and active pulse ratios according to the wavelengths. An arterial calibration curve relates the arterial pulse ratios to a first arterial oxygen saturation value and an active pulse calibration curve relates the active pulse ratios to a second arterial oxygen saturation value. Decision logic outputs one of the first and second arterial oxygen saturation values based upon perfusion and signal quality.
1. An active-pulse blood analysis system comprising:
an optical sensor that illuminates a tissue site with multiple wavelengths of optical radiation and that outputs sensor data responsive to the optical radiation after attenuation by pulsatile blood flow within the tissue site;
one or more filters configured to receive the sensor data and separate the sensor data into arterial pulse data and active-pulse data, wherein the one or more filters comprise a first bandpass filter having a first passband configured to generate the arterial pulse data and a second bandpass filter having a second passband configured to generate the active-pulse data;
one or more memory devices storing an arterial calibration curve that relates arterial pulse ratios to oxygen saturation values;
one or more processor configured to:
receive the arterial pulse data and active-pulse data,
generate an arterial ratio from the arterial pulse data,
generate an active-pulse ratio from the active-pulse data,
output an arterial saturation value (SpO 2 ) by comparing the generated arterial ratio to the arterial calibration curve, and
output a venous oxygen saturation value (SpvO 2 A ) by comparing the generated active-pulse ratio to the arterial calibration curve.
2. The active-pulse blood analysis system of claim 1 , wherein the arterial calibration curve is numerically-derived by correlating arterial blood draws with corresponding sensor data responsive to pulsatile arterial blood flow.
3. The active-pulse blood analysis system of claim 2 , wherein the arterial calibration curve comprises a lookup table.
4. The active-pulse blood analysis system of claim 1 , wherein the first pass band is at a lower range of frequencies and the second pass band is at a higher range of frequencies.
5. An active-pulse blood analysis method comprising:
receiving sensor data responsive to optical radiation after attenuation by pulsatile blood flow within the tissue site from an optical sensor that illuminates a tissue site with multiple wavelengths of optical radiation;
filtering the sensor data to separate the sensor data into arterial pulse data and active-pulse data using a first bandpass filter that has a first passband configured to generate the arterial pulse data and a second bandpass filter that has a second passband so as to generate the active-pulse data;
calculating an arterial ratio from the arterial pulse data;
calculating an active-pulse ratio from the active-pulse data;
outputting an arterial saturation value (SpO 2 ) by comparing the calculated arterial ratio to an arterial calibration curve that relates arterial pulse ratios to oxygen saturation values;
outputting a venous oxygen saturation value (SpvO 2 A ) by comparing the generated active-pulse ratio to the arterial calibration curve.
6. The active-pulse blood analysis method of claim 5 , wherein the arterial calibration curve is numerically-derived by correlating arterial blood draws with corresponding sensor data responsive to pulsatile arterial blood flow.
7. The active-pulse blood analysis method of claim 6 , wherein the arterial calibration curve comprises a lookup table.
8. The active-pulse blood analysis system of claim 5 , wherein the first pass band is at a lower range of frequencies and the second pass band is at a higher range of frequencies.
9. An active-pulse blood analysis method comprising:
inputting optical sensor data;
filtering the optical sensor data into arterial pulse data at a lower range of frequencies and active pulse data at a higher range of frequencies using a first bandpass filter that has a first passband configured to generate the arterial pulse data and a second bandpass filter that has a second passband so as to generate the active-pulse data;
calculating arterial pulse ratios from the arterial pulse data;
calculating active pulse ratios from the active pulse data;
applying an arterial calibration curve stored in one or more memory devices to the arterial pulse ratios so as to generate an SpO 2 parameter indicative of arterial oxygen saturation; and
applying the arterial calibration curve stored in the one or more memory devices to the active pulse ratios so as to generate an SpvO 2 A parameter indicative of venous oxygen saturation.
10. The active-pulse blood analysis method of claim 9 , wherein the arterial calibration curve is numerically-derived by correlating arterial blood draws with corresponding sensor data responsive to pulsatile arterial blood flow.
11. The active-pulse blood analysis method of claim 10 , wherein the arterial calibration curve comprises a lookup table.