Selection of ensemble averaging weights for a pulse oximeter based on signal quality metrics
A pulse oximeter system is presently disclosed. The pulse oximeter system includes a processor and circuitry. The processor and circuitry are configured to receive light waveforms from a sensor, determine at least one signal quality metric for the light waveforms, calculate at least one weight using a continuously variable weighting function based on the at least one signal quality metric, and ensemble average the light waveforms using the at least one calculated weight.
1. A method for monitoring a physiological status of a patient, comprising:
receiving first and second intensity signals representative of an intensity of light of first and second wavelengths, respectively, after attenuation by a patient's tissue;
identifying and qualifying a first sample of the first or second intensity signal related to a first cardiac pulse;
averaging the first sample with a previous sample based on a first weight to provide an averaged sample;
identifying and qualifying a second sample of the first or second intensity signal related to a second cardiac pulse, the second sample being subsequent in time to the first sample;
averaging the second sample with the first averaged sample based on a second weight, to provide a second averaged sample; and
calculating a physiological parameter based on the second averaged sample, wherein the first and second weights are based at least in part on a degree of correlation between the first and second intensity signals.
2. The method of claim 1 , comprising attenuating a low frequency component of the first sample prior to averaging the first sample with the previous sample.
3. The method of claim 1 , wherein the physiological parameter comprises an oxygen saturation of the patient's tissue.
4. The method of claim 1 , wherein the first and second weights are continuously variable.
5. The method of claim 1 , wherein the first and second weights are adjusted based on a frequency, a shape, a derivative skew, a period variability, an amplitude variability, a ratio of a current amplitude to a long-term average amplitude, a ratio of the current amplitude to a previous amplitude, or a ratio of a current pulse period to an average pulse period, or any combination thereof, of one or more of the first or the second intensity signals.
6. The method of claim 1 , wherein the first and second weights are adjusted based on a degree of arrhythmia of one or more of the first or the second intensity signals.
7. The method of claim 1 , comprising tracking an accumulated amount of averaging and providing an indicator when the accumulated amount passes a threshold.
8. The method of claim 1 , wherein the first and second weights are adjusted based on the degree of correlation between the first and second intensity signals over a period of time.
9. The method of claim 8 , wherein the period of time is about three seconds.
10. The method of claim 1 , wherein the first and second wavelengths are different.
11. The method of claim 1 , wherein identifying the first or second sample related to the cardiac pulse comprises examining an amplitude, a shape, or a frequency of the first or second intensity signals.
12. The method of claim 1 , wherein the light of first and second wavelengths is emitted via one or more emitters of a sensor, and wherein the method comprises determining whether the sensor is positioned off of a surface of the patient's tissue based at least in part on one or more quality metrics of the first or second intensity signals.
13. A method for monitoring a patient, comprising:
receiving first and second intensity signals representative of an intensity of light of first and second wavelengths, respectively, after attenuation by a patient's tissue, wherein the light of first and second wavelengths is emitted via one or more emitters of a sensor;
determining one or more quality metrics of the first or second intensity signal;
identifying and qualifying a first sample of the first or second intensity signal related to a first cardiac pulse;
averaging the first sample with a previous sample based on a first weight to provide an averaged sample, wherein the first weight is based on the one or more quality metrics;
calculating a physiological parameter based on the first averaged sample; and
evaluating the one or more quality metrics to determine whether the sensor is positioned off of a surface of the patient's tissue.
14. The method of claim 13 , comprising identifying a second sample of the first or second intensity signal related to a second cardiac pulse, the second sample being subsequent in time to the first sample.
15. The method of claim 14 , comprising discarding the second sample if it is determined that the sensor is positioned off of the surface of the patient's tissue.
16. The method of claim 14 , comprising averaging the second sample with the first averaged sample based on a second weight, to provide a second averaged sample, if it is determined that the sensor is not positioned off of the surface of the patient's tissue.
17. The method of claim 13 , wherein the first weight is based on the degree of correlation between the first and second intensity signals.
18. The method of claim 13 , wherein the first weight is continuously variable.
19. The method of claim 13 , wherein the one or more quality metrics comprise a frequency, a shape, a derivative skew, a period variability, an amplitude variability, a ratio of a current amplitude to a long-term average amplitude, a ratio of the current amplitude to a previous amplitude, or a ratio of a current pulse period to an average pulse period, or any combination thereof.
20. The method of claim 13 , wherein the first and second wavelengths are different.