Methods and systems for qualifying a calculated value based on baseline and deviation information

• US 9,192,310 B2
• Filed: 09/11/2012
• Issued: 11/24/2015
• Est. Priority Date: 09/11/2012
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Rodriguez-Llorente, Fernando, Engelbrecht, Pirow, Wooder, Nicholas James
• Primary Examiner(s): ZEMAN, MARY K
• Application Number:
  US13/609,500
• Publication Number:
  US 20140073867A1
• Time in Patent Office: 1,169 Days
• US Class Current: 1/1
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00

Abstract

A physiological monitoring system may determine physiological information, such as physiological rate information, from a physiological signal. The system may receive a calculated value indicative of a period associated with a physiological rate. The system may determine a first value indicative of a baseline of the physiological signal and a second value indicative of a deviation of the physiological signal from the baseline. The first value may, for example, be a median value, an average, or a coefficient corresponding to a best fit curve of the physiological signal. The second value may be a standard deviation value, a standard error, or a root mean square value based on the physiological signal. The system may qualify or disqualify the calculated value based on the first and second values.

Claims

1. A subject monitoring pulse oximetry system for updating a display rate for 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;

a pulse oximeter coupled to the pulse oximetry sensor;

a display coupled to the pulse oximeter, wherein the display is configured to display the display rate for the subject, wherein;

the pulse oximeter is configured to;

receive the PPG signal;

receive a calculated value that may be indicative of a physiological rate of the subject;

determine a first value indicative of a baseline of the PPG signal;

determine a second value indicative of a deviation of the PPG signal from the baseline;

qualify the calculated value based on the first value and the second value; and

update the display rate on the display based on the qualified value.

2. The system of claim 1, wherein the first value is selected from the group comprising a median value of the PPG signal, an average of the PPG signal, a coefficient corresponding to a best fit curve of the PPG signal, and a combination thereof.

3. The system of claim 1, wherein the second value is selected from the group comprising a standard deviation value based on the PPG signal, a standard error between the PPG signal and the first value, a root mean square value based on the PPG signal, and a combination thereof.

4. The system of claim 1, wherein the pulse oximeter is further configured to perform signal conditioning on the PPG signal based on the calculated value to generate a conditioned PPG signal, wherein the second value is indicative of a deviation of the conditioned PPG signal from the baseline.

5. The system of claim 1, wherein the pulse oximeter is further configured to calculate a metric based on the following expression:

6. The system of claim 5, wherein the pulse oximeter is further configured to compare the metric to a threshold.

7. The system of claim 5, wherein the pulse oximeter is further configured to compare the metric to a history of metric values calculated at respective previous times.

8. A pulse oximetry processing module for updating a display rate for a subject on a display, wherein the pulse oximetry processing module is coupled to the display and comprises non-transitory computer-readable media configured to store instructions that instruct the pulse oximetry processing module to:

receive a photoplethysmographic (PPG) signal from a pulse oximetry sensor, wherein the pulse oximetry sensor detects light attenuated by the subject and generates the PPG signal based on the detected attenuated light;

receive a calculated value that may be indicative of a physiological rate of the subject;

determine a first value indicative of a baseline of the PPG signal;

determine a second value indicative of a deviation of the PPG signal from the baseline;

qualify the calculated value based on the first value and the second value; and

update the display rate on the display based on the qualified value.

9. The pulse oximetry processing module of claim 8, wherein the first value is selected from the group comprising a median value of the PPG signal, an average of the PPG signal, a coefficient corresponding to a best fit curve of the PPG signal, and a combination thereof.

10. The pulse oximetry processing module of claim 8, wherein the second value is selected from the group comprising a standard deviation value based on the PPG signal, a standard error between the PPG signal and the first value, a root mean square value based on the PPG signal, and a combination thereof.

11. The pulse oximetry processing module of claim 8, wherein the non-transitory computer-readable media is further configured to store instructions that instruct the pulse oximetry processing module to perform signal conditioning on the PPG signal based on the calculated value to generate a conditioned PPG signal, wherein the second value is indicative of a deviation of the conditioned PPG signal from the baseline.

12. The pulse oximetry processing module of claim 8, wherein the non-transitory computer-readable media is further configured to calculate a metric based on the following expression:

13. The pulse oximetry processing module of claim 12, wherein the non-transitory computer-readable media is further configured to store instructions that instruct the pulse oximetry processing module to compare the metric to a threshold.

14. The pulse oximetry processing module of claim 12, wherein the non-transitory computer-readable media is further configured to store instructions that instruct the pulse oximetry processing module to compare the metric to a history of metric values calculated at respective previous times.

15. A method for updating a display rate for a subject on a display, comprising:

receiving, using a 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;

receiving, using the pulse oximeter, a calculated value that may be indicative of a physiological rate of the subject;

determining, using the pulse oximeter, a first value indicative of a baseline of the PPG signal;

determining, using the pulse oximeter, a second value indicative of a deviation of the PPG signal from the baseline;

qualifying, using the pulse oximeter, the calculated value based on the first value and the second value; and

updating, using the pulse oximeter, the display rate on the display based on the qualified value.

16. The method of claim 15, wherein the first value is selected from the group comprising a median value of the PPG signal, an average of the PPG signal, a coefficient corresponding to a best fit curve of the PPG signal, and a combination thereof.

17. The method of claim 15, wherein the second value is selected from the group comprising a standard deviation value based on the PPG signal, a standard error between the PPG signal and the first value, a root mean square value based on the PPG signal, and a combination thereof.

18. The method of claim 15, further comprising performing, using the pulse oximeter, signal conditioning on the PPG signal based on the calculated value to generate a conditioned PPG signal, wherein the second value is indicative of a deviation of the conditioned PPG signal from the baseline.

19. The method of claim 15, wherein qualifying the calculated value comprises calculating a metric based on the following expression:

20. The method of claim 19, wherein qualifying the calculated value is based on comparing the metric to a threshold.

21. The method of claim 19, wherein qualifying the calculated value is based on comparing the metric to a history of metric values calculated at respective previous times.

22. A non-transitory computer-readable medium for use in updating a display rate for a subject on a display, the non-transitory computer-readable medium comprising:

computer program instructions recorded thereon for causing a pulse oximeter 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;

receive a calculated value that may be indicative of a physiological rate of the subject;

determine a first value indicative of a baseline of the PPG signal;

determine a second value indicative of a deviation of the PPG signal from the baseline;

qualify the calculated value based on the first value and the second value; and

update the display rate on the display based on the qualified value.

23. The non-transitory computer-readable medium of claim 22, wherein the first value is selected from the group comprising a median value of the PPG signal, an average of the PPG signal, a coefficient corresponding to a best fit curve of the PPG signal, and a combination thereof.

24. The non-transitory computer-readable medium of claim 22, wherein the second value is selected from the group comprising a standard deviation value based on the PPG signal, a standard error between the PPG signal and the first value, a root mean square value based on the PPG signal, and a combination thereof.

25. The non-transitory computer-readable medium of claim 22, comprising further computer program instructions recorded thereon for causing the pulse oximeter to perform signal conditioning on the PPG signal based on the calculated value to generate a conditioned PPG signal, wherein the second value is indicative of a deviation of the conditioned PPG signal from the baseline.

26. The non-transitory computer-readable medium of claim 22, comprising further computer program instructions recorded thereon for causing the pulse oximeter to calculate a metric based on the following expression:

27. The non-transitory computer-readable medium of claim 26, comprising further computer program instructions recorded thereon for causing the pulse oximeter to compare the metric to a threshold.

28. The non-transitory computer-readable medium of claim 26, comprising further computer program instructions recorded thereon for causing the pulse oximeter to compare the metric to a history of metric values calculated at respective previous times.