SYSTEMS AND METHODS FOR MONITORING BLOOD PRESSURE

• US 20150057554A1
• Filed: 08/23/2013
• Published: 02/26/2015
• Est. Priority Date: 08/23/2013
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Watson, James, Manning, Keith, Addison, Paul S.
• Granted Patent: US 10,226,188 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02241 of small dimensions, e.g. adapted to fingers
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• 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 5/7246 using correlation, e.g. template matching or determination of similarity

Abstract

Various methods and systems for blood pressure monitoring are provided. A device for monitoring blood pressure may include a memory storing instructions for receiving one or more signals representative of one or more patient parameters, wherein at least one of the one or more signals comprises a plethysmography signal. The memory also stores instructions for determining a change in a pulse shape metric of the plethysmography signal and determining a change in a blood pressure signal over a period of time based on the one or more signals. The memory also stores instructions for determining a confidence level of the blood pressure signal based at least in part on a correlation between the change in the blood pressure signal and the change in the pulse shape metric over the period of time. The device also includes a processor configured to execute the instructions.

Claims

1. A device for monitoring blood pressure comprising:

a memory storing instructions for;

receiving one or more signals representative of one or more patient parameters, wherein at least one of the one or more signals comprises a plethysmography signal;

determining a change in a pulse shape metric of the plethysmography signal;

determining a change in a blood pressure signal over a period of time based on the one or more signals; and

determining a confidence level of the blood pressure signal based at least in part on a correlation between the change in the blood pressure signal and the change in the pulse shape metric over the period of time; and

a processor configured to execute the instructions.

2. The device of claim 1, wherein the pulse shape metric is a skew of a first derivative of the plethysmography signal.

3. The device of claim 1, wherein determining a confidence level based at least in part on a correlation comprises determining whether the change in the blood pressure signal and the change in the pulse shape metric change in the same direction.

4. The device of claim 3, wherein the memory stores instructions for determining a high confidence level of the blood pressure signal if the blood pressure signal and the pulse shape metric change in the same direction.

5. The device of claim 3, wherein the memory stores instructions for determining a low confidence level of the blood pressure signal if the blood pressure signal and the pulse shape metric do not change in the same direction.

6. The device of claim 1, wherein determining a confidence level based at least in part on a correlation comprises determining a difference between the change in the blood pressure and the change in the pulse shape metric and comparing the difference to a predetermined tolerance.

7. The device of claim 6, wherein the memory stores instructions for determining a high confidence level of the blood pressure signal if the difference between the change in the blood pressure signal and the change in the skew of the first derivative is within the predetermined tolerance.

8. The device of claim 6, wherein the memory stores instructions for determining a low confidence level of the blood pressure signal if the difference between the change in the blood pressure signal and the change in the pulse shape metric is outside of the predetermined tolerance.

9. The device of claim 1, wherein the device is configured to provide the blood pressure signal on a display if a high confidence level is determined.

10. The device of claim 1, wherein the memory stores instructions for discarding the blood pressure signal received over the period of time if a low confidence level is determined.

11. The device of claim 1, wherein the blood pressure signal is based on a differential pulse transit time.

12. A method for determining a confidence level of a blood pressure signal comprising:

using a processor;

receiving a blood pressure signal;

receiving a plethysmography signal;

determining a change in the blood pressure signal over a period of time;

determining a change in a pulse shape metric of the plethysmography signal over the period of time; and

determining whether there is an expected correlation between the change in the blood pressure signal and the change in the pulse shape metric over the period of time.

13. The method of claim 12, wherein the pulse shape metric is a skew of a first derivative of the plethysmography signal.

14. The method of claim 12, comprising determining a high confidence level of the blood pressure signal if the expected correlation is present.

15. The method of claim 14, comprising providing an indication of the confidence level on a display.

16. The method of claim 12, comprising determining a low confidence level of the blood pressure signal if the expected correlation is not present.

17. The method of claim 16, comprising disabling an alarm if the low confidence level is determined.

18. A system for monitoring blood pressure comprising:

a sensor configured to obtain a plethysmography signal;

a monitor comprising circuitry configured to;

receive the plethysmography signal and a blood pressure signal;

calculate a change in the blood pressure signal over a period of time;

calculate a change in a pulse shape metric over the period of time;

compare the change in the blood pressure signal to the change in the pulse shape metric over the period of time to determine a degree of correlation; and

display information related to the blood pressure signal if the degree of correlation is within a threshold.

19. The system of claim 18, wherein the pulse shape metric is a skew of a first derivative of the plethysmography signal.

20. The system of claim 18, wherein the monitor is configured to determine a confidence level of the blood pressure signal over the period of time based at least in part on the degree of correlation.

21. The system of claim 20, wherein the monitor is configured to determine a high confidence level of the blood pressure signal if the blood pressure signal and the skew of the first derivative of the plethysmography signal change in the same direction.

22. The system of claim 18, wherein the monitor is configured to monitor blood pressure based on a scaled skew of the first derivative of the plethysmography signal if the degree of correlation is low.

23. The system of claim 18, wherein the monitor is configured to initiate another blood pressure measurement if the degree of correlation is low.