System and method for detection of unstable oxygen saturation

• US 20070179369A1
• Filed: 01/30/2006
• Published: 08/02/2007
• Est. Priority Date: 01/30/2006
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Nellcor Puritan Bennett Incorporated (Medtronic Plc)
• Inventors: Baker, Clark
• Granted Patent: US 7,706,852 B2
• Time in Patent Office: Days
• US Class Current: 600/323
• CPC Class Codes: A61B 2503/06 Children, e.g. for attention deficit diagnosis
• CPC Class Codes: A61B 5/14551 for measuring blood gases

Abstract

Methods and systems are described for simplified detection of unstable oxygen saturation of a patient by analysis of statistical variations in blood oxygen. One method for automatic detection of unstable oxygen saturation of a patient using a pulse oximeter comprises receiving at least a single time series input of oxygen saturation values and computing at least two metrics based on statistical properties of the single time series input of the oxygen saturation values.

Claims

1. A method for automatic detection of unstable oxygen saturation of a patient using a pulse oximeter, the method comprising:

receiving at least a single time series input of oxygen saturation values; and

computing at least two metrics based on statistical properties of the single time series input of oxygen saturation values.

2. The method as in claim 1, further comprising averaging the statistical metrics.

3. The method as in claim 2, further comprising determining a relationship between the statistical metrics.

4. The method as in claim 3, further comprising providing an output if the relationship exceeds a threshold value.

5. The method as in claim 4, wherein exceeding the threshold value is indicative of cyclic saturation variations.

6. The method as in claim 4, wherein the output comprises sounding an audio alarm.

7. The method as in claim 4, wherein the output comprises displaying a visual alert.

8. The method as in claim 4, wherein the threshold value slope is in a range from about 60% to about 90% of a ratio of time intervals used for quantifying saturation changes.

9. The method as in claim 1, wherein the statistical metrics are associated with ventilation or airway instability.

10. The method as in claim 1, wherein the statistical metrics are associated with sleep apnea.

11. The method as in claim 1, wherein the statistical metrics in combination are sensitive to both magnitude and frequency range of oxygen saturation variations.

12. The method as in claim 1, wherein at least one statistical metric comprises a magnitude of saturation changes over 0.5 to 5 second intervals.

13. The method as in claim 12, wherein a second statistical metric comprises a magnitude of saturation changes over 10 to 30 second intervals.

14. The method as in claim 1, wherein at least one statistical metric comprises a skewness of the single time series input of oxygen saturation values.

15. The method as in claim 1, wherein at least one statistical metric comprises a kurtosis of the single time series input of oxygen saturation values.

16. The method as in claim 1, wherein cyclic saturation variations may be detected with a period of at least 35 seconds to 5 minutes.

17. The method as in claim 1, wherein receiving, computing, averaging, determining, and providing steps are carried out by a processor.

18. The method as in claim 1, further comprising modifying the statistical metrics based on one or more signal quality metrics.

19. The method as in claim 1, further comprising modifying the statistical metrics depending on a magnitude of the oxygen saturation values.

20. The method as in claim 1, further comprising determining whether the oxygen saturation values correspond to unstable oxygen saturation by comparing the oxygen saturation values to multiple thresholds.

21. A method for automatic detection of unstable oxygen saturation of a patient using a pulse oximeter, the method comprising:

receiving at least a single time series input of oxygen saturation values;

computing at least two metrics based on statistical properties of the single time series input of the oxygen saturation values;

modifying the statistical metrics based on one or more signal quality metrics;

averaging the statistical metrics;

determining a relationship between the statistical metrics; and

providing an output if the relationship exceeds a threshold value.

22. A patient monitoring system for automatically detecting unstable oxygen saturation of a patient, the system comprising:

a pulse oximeter for measuring at least a single time series input of oxygen saturation values; and

a processor programmed to compute at least two metrics based on statistical properties of the single time series input of oxygen saturation values.

23. The system as in claim 22, wherein the processor is further programmed to average the statistical metrics.

24. The system as in claim 22, wherein the processor is further programmed to determine a relationship between the statistical metrics.

25. The system as in claim 24, wherein the processor is further programmed to provide an output if the relationship exceeds a threshold value.

26. The system as in claim 25, wherein the statistical metrics are associated with one of cyclic saturation variations, ventilation or airway instability, and sleep apnea.

27. The system as in claim 22, wherein the at least two statistical metrics in combination are sensitive to both magnitude and frequency range of oxygen saturation variations.

28. The system as in claim 22, wherein at least one statistical metric comprises a skewness of the single time series input of oxygen saturation values.

29. The system as in claim 22, wherein at least one statistical metric comprises a kurtosis of the single time series input of oxygen saturation values.

30. The system as in claim 22, wherein the statistical metrics are modified depending on a magnitude of the oxygen saturation values.

31. The system as in claim 22, wherein the oxygen saturation values are determined to correspond to unstable oxygen saturation by comparing the oxygen saturation values to multiple thresholds.

32. A computer-readable storage medium having a computer-readable program embodied therein for directing operation of a computer system, the computer system including a communications system, a processor, and a memory device, wherein the computer-readable program includes instructions for operating the computer to automatically detect unstable oxygen saturation of a patient in accordance with the following:

receiving at least a single time series input of oxygen saturation values; and

computing at least two metrics based on statistical properties of the single time series input of the oxygen saturation values.