Adjusting parameters used in pulse oximetry analysis
View Patent ↗Adjusting a pulse qualification criterion includes receiving a signal representing a plurality of pulses, where the signal is generated in response to detecting light scattered from blood perfused tissue. A characteristic is determined. A pulse qualification criterion used for qualifying a pulse is adjusted in accordance with the characteristic. The pulses are evaluated according to the pulse qualification criterion.
1. A method for adjusting a weight of a saturation filtering process, comprising:
receiving a signal from a sensor representing one or more pulses, the signal generated in response to detecting light scattered from blood perfused tissue, the light comprising a first wavelength and a second wavelength; and
using a processor:
determining a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
determining a pulse quality metric indicating the quality of the one or more pulses; and
adjusting a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric, the saturation weight representing a weight used for a filtering process operable to filter a saturation estimate of the blood perfused tissue.
2. The method of claim 1 , comprising:
establishing that the filtering process is in a predetermined response mode.
3. The method of claim 1 , wherein adjusting a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric further comprises:
modifying a noise variance in accordance with the pulse quality metric; and
adjusting the saturation weight in accordance with the modified noise variance.
4. The method of claim 1 , wherein the saturation weight is calculated by a Kalman filter.
5. A method for calculating saturation, comprising:
receiving a signal from a sensor representing one or more pulses, the signal generated in response to detecting light scattered from blood perfused tissue, the light comprising a first wavelength and a second wavelength;
using a processor:
determining a pulse quality metric indicating the quality of the one or more pulses;
determining a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
establishing a ratio-of-ratios weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric;
filtering the ratio-of-ratios in accordance with the ratio-of-ratios weight; and
calculating saturation according to the filtered ratio-of ratios; and
displaying the saturation on a display.
6. The method of claim 5 , comprising:
establishing that the filtering process is in a predetermined response mode.
7. A system operable to adjust a weight of a saturation filtering process, comprising:
an interface operable to:
receive a signal representing one or more pulses, the signal generated in response to detecting light scattered from blood perfused tissue, the light comprising a first wavelength and a second wavelength; and
a processor operable to:
determine a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
determine a pulse quality metric indicating the quality of the one or more pulses; and
adjust a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric, a saturation weight representing a weight used for a filtering process operable to filter the saturation estimate of the blood perfused tissue.
8. The system of claim 7 , the processor further operable to:
establish that the filtering process is in a predetermined response mode.
9. The system of claim 7 , the processor further operable to adjust a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric by:
modifying a noise variance in accordance with the pulse quality metric; and
adjusting the saturation weight in accordance with the modified noise variance.
10. The system of claim 7 , wherein the saturation weight is calculated by a Kalman filter.
11. A system for adjusting a weight of a saturation filtering process, comprising:
an interface operable to:
receive a signal representing one or more pulses, the signal generated in response to detecting light scattered from blood perfused tissue, the light comprising a first wavelength and a second wavelength; and
a processor operable to:
determine a pulse quality metric indicating the quality of the one or more pulses;
determine a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
establish a ratio-of-ratios weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric;
filter the ratio-of-ratios in accordance with the ratio-of-ratios weight; and
calculate saturation according to the filtered ratio-of ratios.
12. The system of claim 11 , the processor further operable to establish that the filtering process is in a predetermined response mode.
13. A system for adjusting a weight of a saturation filtering process, comprising:
means for receiving a signal representing one or more pulses, the signal generated in response to detecting light scattered from blood perfused tissue, the light comprising a first wavelength and a second wavelength;
means for determining a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
means for determining a pulse quality metric indicating the quality of the one or more pulses; and
means for adjusting a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric, the saturation weight representing a weight used for a filtering process operable to filter a saturation estimate of the blood perfused tissue.
14. A system operable to adjust a weight of a saturation filtering process, comprising:
an interface operable to:
receive a signal representing one or more pulses, the signal generated in response to detecting light scattered from blood perfused tissue, the light comprising a first wavelength and a second wavelength; and
a processor operable to:
determine a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
determine a pulse quality metric indicating the quality of the one or more pulses;
establish that the filtering process is in a predetermined response mode; and
adjust a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric, the saturation weight representing a weight used for a filtering process operable to filter a saturation estimate of the blood perfused tissue, the saturation weight calculated by a Kalman filter, the saturation weight adjusted by:
modifying a noise variance in accordance with the pulse quality metric; and
adjusting the saturation weight in accordance with the modified noise variance.
15. A system, comprising:
a sensor comprising:
one or more light sources adapted to emit light at a first wavelength and a second wavelength into blood perfused tissue; and
a photodetector adapted to detect the light scattered from the blood perfused tissue; and
a monitor comprising:
an interface adapted to couple the sensor to the monitor, the interface operable to receive a signal representing one or more pulses based on the detected light; and
a processor operable to:
determine a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
determine a pulse quality metric indicating the quality of the one or more pulses; and
adjust a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric, a saturation weight representing a weight used for a filtering process operable to filter the saturation estimate of the blood perfused tissue.
16. The system of claim 15 , the processor further operable to adjust a saturation weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric by:
modifying a noise variance in accordance with the pulse quality metric; and
adjusting the saturation weight in accordance with the modified noise variance.
17. The system of claim 15 , wherein the saturation weight is calculated by a Kalman filter.
18. A system, comprising:
a sensor comprising:
one or more light sources adapted to emit light at a first wavelength and a second wavelength into blood perfused tissue; and
a photodetector adapted to detect the light scattered from the blood perfused tissue; and
a monitor comprising:
an interface adapted to couple the sensor to the monitor, the interface operable to receive a signal representing one or more pulses based on the detected light;
a processor operable to:
determine a pulse quality metric indicating the quality of the one or more pulses;
determine a ratio-of-ratios variability metric indicating the variation of a ratio-of-ratios, a ratio-of-ratios representing the ratio of absorbances of the first wavelength and the second wavelength;
establish a ratio-of-ratios weight in accordance with the ratio-of-ratios variability metric and the pulse quality metric;
filter the ratio-of-ratios in accordance with the ratio-of-ratios weight; and
calculate saturation according to the filtered ratio-of ratios; and
a display operable to display the calculated saturation.
19. The system of claim 18 , the processor further operable to:
establish that the filtering process is in a predetermined response mode.