Methods and systems for determining noise information from a physiological signal
View Patent ↗A physiological monitoring system may determine physiological information, such as physiological rate information, and other information, such as noise information, from a physiological signal. The system may generate a first difference signal based on a first segment of the physiological signal and sort the first difference signal to generate a first sorted difference signal. The system may generate a second difference signal based on a second segment of the physiological signal and sort the second difference signal to generate a second sorted difference signal. The first and second sorted difference signals may be analyzed and a value indicative of noise may be determined based on the analysis.
1. A pulse oximetry monitoring system for determining pulse rate of a subject, comprising:
a pulse oximetry sensor configured to detect light attenuated by the subject and generate a photoplethysmographic (PPG) signal based on the detected attenuated light; and
a pulse oximeter coupled to the pulse oximetry sensor, wherein the pulse oximeter is configured to:
store a rate algorithm;
generate a first difference signal based on a first segment of the PPG signal;
sort the first difference signal to generate a first sorted difference signal;
generate a second difference signal based on a second segment of the PPG signal;
sort the second difference signal to generate a second sorted difference signal;
analyze the first sorted difference signal and the second sorted difference signal;
determine a value indicative of noise based on the analysis of the first sorted difference signal and the second sorted difference signal;
determine an algorithm setting based on the value indicative of noise;
apply the algorithm setting to the rate algorithm stored by the pulse oximeter to thereby update the rate algorithm; and
determine the pulse rate of the subject using the updated rate algorithm and the PPG signal.
2. The system of claim 1 , wherein the pulse oximeter is further configured to:
determine a first line fit having a first slope for the first sorted difference signal;
determine a second line fit having a second slope for the second sorted difference signal; and
determine a difference between the first slope and the second slope.
3. The system of claim 1 , wherein the pulse oximeter is further configured to:
determine a first line fit for the first sorted difference signal;
determine a second line fit for the second sorted difference signal;
determine a goodness of fit associated with the first line fit; and
determine a goodness of fit associated with the second line fit.
4. The system of claim 1 , wherein the pulse oximeter is further configured to determine a goodness of fit between the first sorted difference signal and the second sorted difference signal.
5. The system of claim 1 , wherein the pulse oximeter is further configured to determine a value indicative of differences between the first sorted difference signal and the second sorted difference signal.
6. A pulse oximetry processing module for determining pulse rate of a subject, wherein the pulse oximetry processing module comprises a non-transitory computer readable medium having instructions stored thereon, wherein the instructions comprise a rate algorithm, and wherein the instructions are configured to instruct the pulse oximetry processing module to:
receive a photoplethysmographic (PPG) signal derived from a pulse oximetry sensor output, wherein the pulse oximetry sensor detects light attenuated by the subject and generates the PPG signal based on the detected attenuated light;
generate a first difference signal based on a first segment of the PPG signal;
sort the first difference signal to generate a first sorted difference signal;
generate a second difference signal based on a second segment of the PPG signal;
sort the second difference signal to generate a second sorted difference signal;
analyze the first sorted difference signal and the second sorted difference signal;
determine a value indicative of noise based on the analysis of the first sorted difference signal and the second sorted difference signal;
determine an algorithm setting based on the value indicative of noise;
apply the algorithm setting to the stored rate algorithm to thereby update the rate algorithm; and
determine the pulse rate of the subject using the updated rate algorithm and the PPG signal.
7. The pulse oximetry processing module of claim 6 , wherein the instructions are further configured to instruct the pulse oximetry processing module to:
determine a first line fit having a first slope for the first sorted difference signal;
determine a second line fit having a second slope for the second sorted difference signal; and
determine a difference between the first slope and the second slope.
8. The pulse oximetry processing module of claim 6 , wherein the instructions are further configured to instruct the pulse oximetry processing module to:
determine a first line fit for the first sorted difference signal;
determine a second line fit for the second sorted difference signal;
determine a goodness of fit associated with the first line fit; and
determine a goodness of fit associated with the second line fit.
9. The pulse oximetry processing module of claim 6 , wherein the instructions are further configured to instruct the pulse oximetry processing module to determine a goodness of fit between the first sorted difference signal and the second sorted difference signal.
10. The pulse oximetry processing module of claim 6 , wherein the instructions are further configured to instruct the pulse oximetry processing module to determine a value indicative of differences between the first sorted difference signal and the second sorted difference signal.
11. A method for determining pulse rate of a subject, comprising:
storing, using a pulse oximeter, a rate algorithm;
receiving, using the pulse oximeter, a photoplethysmographic (PPG) signal derived from a pulse oximetry sensor output, wherein the pulse oximetry sensor detects light attenuated by the subject and generates the PPG signal based on the detected attenuated light;
generating, using the pulse oximeter, a first difference signal based on a first segment of the PPG signal;
sorting, using the pulse oximeter, the first difference signal to generate a first sorted difference signal;
generating, using the pulse oximeter, a second difference signal based on a second segment of the PPG signal;
sorting, using the pulse oximeter, the second difference signal to generate a second sorted difference signal;
analyzing, using the pulse oximeter, the first sorted difference signal and the second sorted difference signal;
determining, using the pulse oximeter, a value indicative of noise based on the analysis of the first sorted difference signal and the second sorted difference signal;
determining, using the pulse oximeter, an algorithm setting based on the value indicative of noise;
applying, using the pulse oximeter, the algorithm setting to the rate algorithm stored by the pulse oximeter thereby updating the rate algorithm; and
determining, using the pulse oximeter, the pulse rate of the subject using the updated rate algorithm and the PPG signal.
12. The method of claim 11 , wherein analyzing the first sorted difference signal and the second sorted difference signal comprises:
determining a first line fit having a first slope for the first sorted difference signal;
determining a second line fit having a second slope for the second sorted difference signal; and
determining a difference between the first slope and the second slope.
13. The method of claim 11 , wherein analyzing the first sorted difference signal and the second sorted difference signal comprises:
determining a first line fit for the first sorted difference signal;
determining a second line fit for the second sorted difference signal;
determining a goodness of fit associated with the first line fit; and
determining a goodness of fit associated with the second line fit.
14. The method of claim 11 , wherein analyzing the first sorted difference signal and the second sorted difference signal comprises determining a goodness of fit between the first sorted difference signal and the second sorted difference signal.
15. The method of claim 11 , wherein analyzing the first sorted difference signal and the second sorted difference signal comprises determining a value indicative of differences between the first sorted difference signal and the second sorted difference signal.
16. A non-transitory computer-readable medium for use in determining the pulse rate of a subject, the computer-readable medium comprising:
computer program instructions recorded thereon for causing a pulse oximeter storing a rate algorithm to:
receive a photoplethysmographic (PPG) signal derived from a pulse oximetry sensor output, wherein the pulse oximetry sensor detects light attenuated by the subject and generates the PPG signal based on the detected attenuated light;
generate a first difference signal based on a first segment of the PPG signal;
sort the first difference signal to generate a first sorted difference signal;
generate a second difference signal based on a second segment of the PPG signal;
sort the second difference signal to generate a second sorted difference signal;
analyzing the first sorted difference signal and the second sorted difference signal;
determine a value indicative of noise based on the analysis of the first sorted difference signal and the second sorted difference signal;
determine an algorithm setting based on the value indicative of noise;
apply the algorithm setting to the stored rate algorithm to thereby update the rate algorithm; and
determine the pulse rate of the subject using the updated rate algorithm and the PPG signal.
17. The non-transitory computer-readable medium of claim 16 , comprising further computer program instructions recorded thereon for causing the pulse oximeter to:
determine a first line fit having a first slope for the first sorted difference signal;
determine a second line fit having a second slope for the second sorted difference signal; and
determine a difference between the first slope and the second slope.
18. The computer-readable medium of claim 16 , comprising further computer program instructions recorded thereon for causing the pulse oximeter to:
determine a first line fit for the first sorted difference signal;
determine a second line fit for the second sorted difference signal;
determine a goodness of fit associated with the first line fit; and
determine a goodness of fit associated with the second line fit.
19. The computer-readable medium of claim 16 , comprising further computer program instructions recorded thereon for causing the pulse oximeter to determine a goodness of fit between the first sorted difference signal and the second sorted difference signal.
20. The computer-readable medium of claim 16 , comprising further computer program instructions recorded thereon for causing the pulse oximeter to determine a value indicative of differences between the first sorted difference signal and the second sorted difference signal.