Method for improved oxygen saturation estimation in the presence of noise
View Patent ↗The present disclosure relates, according to some embodiments, to devices, systems, and methods for estimating a physiological parameter in the presence of noise. For example, the disclosure relates, in some embodiments, to devices, systems, and methods for assessing (e.g., estimating, measuring, calculating) oxygen saturation (SpO2). Methods of assessing SpO2 may include assessing a noise metric associated with motion artifact. In some embodiments, a percentage (e.g., an empirically determined percentage) of a noise metric may be simply added to the SpO2 estimate to produce a corrected SpO2 estimate. An oximetry algorithm may include, according to some embodiments, combining multiple internal SpO2 estimates and associated noise and/or signal quality metrics (e.g., using a radial basis neural network) to produce a modified (e.g., corrected) SpO2 estimate (e.g., rather than merely selecting the estimate from a finite number of candidates). A modified SpO2 estimate may include little or no movement-based error.
1. A method for estimating oxygen saturation in the presence of noise, the method comprising:
determining a change in estimated oxygen saturation comprising calculating a difference between a first estimated oxygen saturation value at a first time and a second estimated oxygen saturation value at a second time;
determining a change in a saturation noise estimate between a first saturation noise estimate at the first time and a second saturation noise estimate at the second time, wherein the change in the saturation noise estimate attends the change in estimated oxygen saturation;
selecting either the first estimated oxygen saturation value or the second estimated oxygen saturation value based at least in part on a comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate; and
displaying the selected estimated oxygen saturation value.
2. The method of claim 1 , wherein the comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate comprises determining whether the change in the estimated oxygen saturation is at least a certain percentage larger than the change in the saturation noise estimate.
3. The method of claim 1 , comprising initiating an alarm if the selected estimated oxygen saturation value exceeds an alarm threshold.
4. The method of claim 1 , comprising processing the selected oxygen saturation estimate value using a radial basis neural network to produce a modified oxygen saturation estimate.
5. A system for estimating oxygen saturation in the presence of noise, comprising:
a processor configured to:
determine a change in estimated oxygen saturation comprising calculating a difference between a first estimated oxygen saturation value at a first time and a second estimated oxygen saturation value at a second time;
determine a change in a saturation noise estimate between a first saturation noise estimate at the first time and a second saturation noise estimate at the second time, wherein the change in the saturation noise estimate attends the change in estimated oxygen saturation;
select either the first estimated oxygen saturation value or the second estimated oxygen saturation value based at least in part on a comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate; and
a display configured to display the selected estimated oxygen saturation value.
6. The system of claim 5 , wherein the comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate comprises determining whether the change in the estimated oxygen saturation is at least a certain percentage larger than the change in the saturation noise estimate.
7. The system of claim 5 , wherein the processor is configured to process the selected oxygen saturation estimate value using a radial basis neural network to produce a modified oxygen saturation estimate.
8. A method for estimating oxygen saturation in the presence of noise, the method comprising:
determining a change in estimated oxygen saturation comprising calculating a difference between a first estimated oxygen saturation value at a first time and a second estimated oxygen saturation value at a second time;
determining a change in a saturation noise estimate between a first saturation noise estimate and a second saturation noise estimate, wherein the change in the saturation noise estimate attends the change in estimated oxygen saturation;
selecting either the first estimated oxygen saturation value or the second estimated oxygen saturation value based at least in part on a comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate, wherein the comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate comprises determining whether the change in the estimated oxygen saturation is at least a certain percentage larger than the change in the saturation noise estimate; and
displaying the selected estimated oxygen saturation value.
9. The method of claim 8 , comprising processing the selected oxygen saturation estimate value using a radial basis neural network to produce a modified oxygen saturation estimate.
10. The method of claim 8 , wherein the comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate comprises determining whether the change in the estimated oxygen saturation is at least one hundred percent larger than the change in the saturation noise estimate.
11. The method of claim 10 , comprising selecting the first estimated oxygen saturation value if the change in the estimated oxygen saturation is less than one hundred percent larger than the change in the saturation noise estimate.
12. The method of claim 10 , comprising selecting the second estimated oxygen saturation value if the change in the estimated oxygen saturation is equal to or greater than one hundred percent larger than the change in the saturation noise estimate.
13. A method for estimating oxygen saturation in the presence of noise, the method comprising:
determining a change in estimated oxygen saturation comprising calculating a difference between a first estimated oxygen saturation value at a first time and a second estimated oxygen saturation value at a second time;
determining a change in a saturation noise estimate between a first saturation noise estimate and a second saturation noise estimate, wherein the change in the saturation noise estimate attends the change in estimated oxygen saturation;
selecting either the first estimated oxygen saturation value or the second estimated oxygen saturation value based at least in part on a comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate;
processing the selected oxygen saturation estimate value using a radial basis neural network to produce a modified oxygen saturation estimate; and
displaying the modified oxygen saturation estimate.
14. The method of claim 13 , wherein the comparison between the change in the estimated oxygen saturation and the change in the saturation noise estimate comprises determining whether the change in the estimated oxygen saturation is at least 100 percent larger than the change in the saturation noise estimate.
15. The method of claim 13 , wherein displaying the selected estimated oxygen saturation value comprises displaying the modified oxygen saturation estimate.
16. The method of claim 13 , wherein the radial basis neural network comprises a single-hidden-layer network.
17. The method of claim 16 , wherein the single-hidden-layer network comprises n unique inputs, m nodes in a hidden layer, and a single linear node in an output layer.
18. The method of claim 13 , comprising comparing the modified oxygen saturation estimate to a hypoxia oxygen saturation threshold.
19. The method of claim 18 , comprising initiating an alarm if the modified oxygen saturation estimate is less than or equal to the hypoxia oxygen saturation threshold.
20. The method of claim 13 , wherein the modified oxygen saturation estimate is based at least in part on a combination of the selected oxygen saturation estimate value and a corresponding signal quality metric.
21. The method of claim 13 , wherein the modified oxygen saturation estimate has less noise bias than the selected oxygen saturation estimate value.