Pulse oximetry data confidence indicator

• US 20040133087A1
• Filed: 12/18/2003
• Published: 07/08/2004
• Est. Priority Date: 01/07/1999
• Status: Active Grant

• Current Assignee: Ammar A.L. Ali, Divya S. Breed, Jerome J. Novak, Massi E. Kiani
• Original Assignee: Ammar A.L. Ali, Divya S. Breed, Jerome J. Novak, Massi E. Kiani
• Inventors: Kiani, Massi E., Novak, Jerome J., Ali, Ammar Al, Breed, Divya S.
• Granted Patent: US 6,996,427 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7405 using sound
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A data confidence indicator includes a plurality of physiological data and a plurality of signal quality measures derived from a physiological sensor output, and a plurality of comparator outputs each responsive to one of the measures and a corresponding one of a plurality of thresholds. An alert trigger output combines the comparator outputs. A low signal quality warning is generated in response to the alert trigger output, wherein the thresholds are set so that the warning occurs during a time period when there is low confidence in the data. The alert may be in the form of a message generated on the pulse oximeter display to warn that the accuracy of saturation and pulse rate measurements may be compromised. A confidence-based alarm utilizes signal quality measures to reduce the probability of false alarms when data confidence is low and to reduce the probability of missed events when data confidence is high.

Claims

1. A device capable of displaying physiological data and an indication of the reliability of the physiological data, the device comprising:

a plurality of physiological data acquired from an output of a physiological sensor, wherein the output is related to one or more physiological parameters of a patient;

a plurality of signal quality measures derived from the physiological sensor output;

a confidence measure derived from at least one of the plurality of signal quality measures and corresponding to at least one of the plurality of physiological data; and

a display presenting data representative of the confidence measure and presenting data representative of the plurality of physiological data.

2. The device of claim 1, wherein the display includes an audio transducer and wherein the transducer presents the data representative of the confidence measure as an audible signal.

3. The device of claim 2, wherein a volume of the audible signal is varied to indicate the confidence measure.

4. The device of claim 3, wherein the volume is raised as the confidence measure becomes more positive and lowered as the confidence measure becomes less positive.

5. The device of claim 2, wherein the audible signal comprises a plurality of beeps.

6. The device of claim 1, wherein the display presents the data representative of the confidence measure in a bar display.

7. The device of claim 6, wherein the bar display pulses with a pulse of the patient.

8. The device of claim 6, wherein a height of the bar display is varied to indicate the confidence measure.

9. The device of claim 8, wherein the height of the bar display is raised as the confidence measure becomes more positive and lowered as the confidence measure becomes less positive.

10. The device of claim 1, further comprising:

a buffer configured to timeshift the plurality of physiological data by a delay to generate a delayed data set;

a threshold setting a limit for the plurality of physiological data and the delayed data set; and

a warning generated when levels of the plurality of physiological data and the delayed data set are beyond said threshold.

11. The device of claim 10, wherein the delay is a function of the confidence measure.

12. The device of claim 1, further comprising:

a smoothing filter for the plurality of physiological data;

an adjustment for the smoothing filter that is a function of the confidence measure; and

an alarm generated when the plurality of physiological data passed through the smoothing filter falls below an alarm threshold.

13. The device of claim 1, wherein the confidence measure depends on at least one of an integrity measure, a pulse rate density measure and a harmonic ratio measure.

14. The device of claim 14, wherein an alert is provided when each of the integrity measure, the pulse rate density measure, and the harmonic ratio measure falls below one or more thresholds associated with each of the integrity measure, the pulse rate density measure, and the harmonic ratio measure.

15. A method of providing a caregiver an indication of signal quality acquired from a physiological signal output from a physiological sensor, the method comprising:

acquiring a physiological data set from the physiological sensor output, wherein the physiological sensor output is related to one or more physiological parameters of a patient;

deriving a plurality of signal quality measures from the physiological sensor output;

comparing the plurality of signal quality measures to a corresponding plurality of thresholds to determine a confidence measure, the confidence measure corresponding to the physiological data set; and

presenting data representative of the confidence measure and data representative of the physiological data set.

16. The method of claim 15, wherein the step of presenting the data representative of the confidence measure further comprises issuing an audible signal.

17. The method of claim 16, wherein the step of issuing the audible signal further comprises varying a volume of the audible signal to indicate the confidence measure.

18. The method of claim 17, wherein the step of varying the volume of the audible signal further comprises raising the volume as the confidence measure becomes more positive and lowering the volume as the confidence measure becomes less positive.

19. The method of claim 16, wherein the audible signal comprises a plurality of beeps.

20. The method of claim 15, wherein the step of presenting further comprises presenting a bar display.

21. The method of claim 20, wherein the step of presenting the bar display further comprises pulsing the bar display with a pulse of the patient.

22. The method of claim 20, wherein the step of presenting the bar display further comprises varying a height of the bar display to indicate the confidence measure.

23. The method of claim 22, wherein the step of varying the height of the bar display further comprises raising the height of the bar display as the confidence measure becomes more positive and lowering the height of the bar display as the confidence measure becomes less positive.

24. The method of claim 15, further comprising the steps of:

timeshifting the physiological data set by a delay to generate a delayed data set;

comparing the physiological data set and the delayed data set to a threshold; and

generating a warning when levels of the physiological data set and the delayed data set are beyond said threshold.

25. The method of claim 24, wherein the delay is a function of the confidence measure.

26. The method of claim 15, further comprising the steps of:

applying a smoothing filter to the physiological data set;

adjusting parameters of the smoothing filter as a function of the confidence measure; and

generating an alarm when the physiological data set passed through the smoothing filter falls below an alarm threshold.

27. The method of claim 15, wherein the confidence measure depends on at least one of an integrity measure, a pulse rate density measure and a harmonic ratio measure.

28. The method of claim 27, further comprising the step of generating an alert when each of the integrity measure, the pulse rate density measure, and the harmonic ratio measure falls below one or more thresholds associated with each of the integrity measure, the pulse rate density measure, and the harmonic ratio measure.

29. A data confidence indication method comprising the steps of:

acquiring a signal from a physiological sensor;

calculating a physiological data set from said signal;

calculating a plurality of signal quality measures from said signal;

setting an alarm threshold for said data set; and

delaying an alarm trigger when said data set exceeds said threshold as a function of at least one of said signal quality measures so as to reduce the probability of false alarms.

30. The method of claim 29, further comprising the step of comparing the plurality of signal quality measures to a corresponding plurality of thresholds to determine a confidence measure, the confidence measure corresponding to the physiological data set.

31. The method of claim 30, further comprising the step of presenting data representative of the confidence measure and data representative of the physiological data set.

32. The method of claim 31, wherein the step of presenting the data representative of the confidence measure further comprises issuing an audible signal.

33. The method of claim 32, wherein the step of issuing the audible signal further comprises varying a volume of the audible signal to indicate the confidence measure.

34. The method of claim 33, wherein the step of varying the volume of the audible signal further comprises raising the volume as the confidence measure becomes more positive and lowering the volume as the confidence measure becomes less positive.

35. The method of claim 32, wherein the audible signal comprises a plurality of beeps.

36. The method of claim 31, wherein the step of presenting further comprises presenting a bar display.

37. The method of claim 36, wherein the step of presenting the bar display further comprises pulsing the bar display with a pulse of the patient.

38. The method of claim 36, wherein the step of presenting the bar display further comprises varying a height of the bar display to indicate the confidence measure.

39. The method of claim 38, wherein the step of varying the height of the bar display further comprises raising the height of the bar display as the confidence measure becomes more positive and lowering the height of the bar display as the confidence measure becomes less positive.