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. A blood analysis method comprising:
inputting optical sensor data;
determining arterial pulse data from the optical sensor data;
calculating arterial pulse ratios from the arterial pulse data;
determining active pulse data from the optical sensor 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 determined from an arterial pulse;
applying an active pulse calibration curve stored in the one or more memory devices to the active pulse ratios so as to generate an SpO 2 AP parameter indicative of arterial oxygen saturation determined from an active pulse; and
choosing between the SpO 2 parameter and the SpO 2 AP parameter so as to generate an SpO 2 M output parameter, the SpO 2 M output parameter comprising either the SpO 2 parameter or the SpO 2 AP parameter based on signal conditions of the optical sensor data a Boolean signal quality (BSQ) and a Boolean perfusion index (BPI).
2. The blood analysis method of claim 1 , wherein the SpO 2 M output parameter is indicative of an arterial oxygen saturation measurement tolerant to at least one of motion, low perfusion, and low signal quality.
3. The blood analysis method of claim 1 , further comprising measuring a perfusion index (PI), and wherein the Boolean perfusion input (BPI) is zero when the perfusion index (PI) is below a first threshold boundary.
4. The blood analysis method of claim 3 , further comprising measuring an acceleration of an optical sensor, and wherein the Boolean signal quality (BSQ) is zero when the measured acceleration is above a second threshold boundary.
5. The blood analysis method of claim 4 , wherein the first threshold boundary is a perfusion index (PI) of 1%.
6. The blood analysis method of claim 5 , wherein the second threshold boundary is an acceleration of 0.3 g.
7. The blood analysis method of claim 1 , wherein the arterial calibration curve relates arterial pulse ratios to oxygen saturation values.
8. The blood analysis method of claim 7 , wherein the active pulse calibration curve relates active pulse ratios to oxygen saturation values.
9. A blood analysis system comprising:
an optical sensor configured to transmit multiple wavelengths of light into a tissue site and to detect the transmitted light after attenuation by arterial blood flow and active pulsed blood flow within the tissue site so as to generate optical sensor data;
one or more memory devices storing an arterial calibration curve and an active pulse calibration curve; and
a processor configured to:
determine arterial pulse data from the optical sensor data and determine arterial pulse ratios from the arterial pulse data;
determine active pulse data from the optical sensor data and determine active pulse ratios from the active pulse data;
apply the arterial calibration curve to the arterial pulse ratios so as to generate an SpO 2 parameter indicative of arterial oxygen saturation determined from an arterial pulse;
apply the active pulse calibration curve to the active pulse ratios so as to generate an SpO 2 AP parameter indicative of arterial oxygen saturation determined from an active pulse; and
select between the SpO 2 parameter and the SpO 2 AP parameter so as to generate an SpO 2 M output parameter, the SpO 2 M output parameter comprising either the SpO 2 parameter or the SpO 2 AP parameter based on a Boolean signal quality (BSQ) and a Boolean perfusion index (BPI) of the optical sensor data.
10. The blood analysis system of claim 9 , wherein the SpO 2 M output parameter is indicative of an arterial oxygen saturation measurement tolerant to at least one of motion, low perfusion, and low signal quality.
11. The blood analysis system of claim 9 , wherein the processor is further configure to determine a perfusion index (PI), and wherein the Boolean perfusion input (BPI) is zero when the perfusion index (PI) is below a first threshold boundary.
12. The blood analysis system of claim 11 , further comprising an accelerometer associated with the optical sensor, and wherein the Boolean signal quality (BSQ) is zero when a measured acceleration is above a second threshold boundary.
13. The blood analysis system of claim 12 , wherein the first threshold boundary is a perfusion index (PI) of 1%.
14. The blood analysis system of claim 13 , wherein the second threshold boundary is an acceleration of 0.3 g.
15. The blood analysis system of claim 9 , wherein the arterial calibration curve relates arterial pulse ratios to oxygen saturation values.
16. The blood analysis system of claim 9 , wherein the active pulse calibration curve relates active pulse ratios to oxygen saturation values.