SYSTEM AND METHOD FOR MONITORING AUTOREGULATION UTILIZING NORMALIZED REGIONAL OXYGEN SATURATION VALUES

• US 20170095161A1
• Filed: 10/05/2016
• Published: 04/06/2017
• Est. Priority Date: 10/06/2015
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Addison, Paul Stanley, Watson, James N., Montgomery, Dean
• Granted Patent: US 11,096,588 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/7246 using correlation, e.g. template matching or determination of similarity
• CPC Class Codes: A61B 5/7405 using sound
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• 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

Abstract

A method for monitoring autoregulation includes, using a processor, receiving a blood pressure signal an oxygen saturation signal, and a regional oxygen saturation signal from a patient. The method also includes normalizing the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal. The method further includes determining a linear correlation between the blood pressure signal and the normalized regional oxygen saturation signal. The method still further includes providing a signal indicative of the patient'"'"'s autoregulation status to an output device based on the linear correlation.

Claims

1. A method for monitoring autoregulation, comprising:

utilizing a processor to execute one or more routines encoded on a memory for;

receiving a blood pressure signal, an oxygen saturation signal, and a regional oxygen saturation signal from a patient;

normalizing the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal;

determining a linear correlation between the blood pressure signal and the normalized regional oxygen saturation signal; and

providing a signal indicative of the patient'"'"'s autoregulation status to an output device based on the linear correlation.

2. The method of claim 1, comprising providing a cerebral oximetry index value to the output device.

3. The method of claim 2, comprising providing a normalized regional oxygen saturation value derived from the normalized regional oxygen saturation signal to the output device.

4. The method of claim 3, comprising providing a regional oxygen saturation value derived from the regional oxygen saturation signal and corresponding to the normalized regional oxygen saturation value to the output device.

5. The method of claim 1, comprising utilizing historical data to derive the relationship between the oxygen saturation signal and the regional oxygen saturation signal.

6. The method of claim 1, comprising generating a curve based on the oxygen saturation signal and the regional oxygen saturation signal to derive the relationship between the oxygen saturation signal and the oxygen saturation signal.

7. The method of claim 6, comprising fitting a line of best fit to the curve and extracting a gradient of the line.

8. The method of claim 7, comprising utilizing the gradient of the line in normalizing the regional oxygen saturation signal to correct for variation in the oxygen saturation signal.

9. The method of claim 1, comprising determining based on an amount of data gathered from the oxygen saturation signal and the regional oxygen saturation signal whether to utilize historical data or to utilize a gradient extracted from a best fit line of a curve generated from the oxygen saturation signal and the regional oxygen saturation signal to derive the relationship between the oxygen saturation signal and the regional oxygen saturation signal.

10. The method of claim 1, comprising normalizing the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal only if a quality metric of a correlation between the oxygen saturation signal and the regional oxygen saturation is above a threshold value.

11. The method of claim 1, comprising normalizing the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal only if an oxygen saturation value derived from the oxygen saturation signal falls below an oxygen saturation threshold value.

12. The method of claim 1, wherein normalizing the regional oxygen saturation signal to correct for variation in the oxygen saturation signal comprises compensating for a time delay in receiving the oxygen saturation signal.

13. A monitor for monitoring autoregulation, comprising:

a memory encoding one or more processor-executable routines; and

a processor configured to access and execute the one or more routines encoded by the memory, wherein the routines, when executed cause the processor to;

receive a blood pressure signal, an oxygen saturation signal, and a regional oxygen saturation signal from a patient;

normalize the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal;

determine a linear correlation between the blood pressure signal and the normalized regional oxygen saturation signal; and

provide a signal indicative of the patient'"'"'s autoregulation status to an output device based on the linear correlation.

14. The monitor of claim 13, wherein the one or more routines, when executed cause the processor to utilize historical data to derive the relationship between the oxygen saturation signal and the regional oxygen saturation signal.

15. The monitor of claim 13, wherein the one or more routines, when executed cause the processor to generate a curve based on the oxygen saturation signal and the regional oxygen saturation signal to derive the relationship between the oxygen saturation signal and the oxygen saturation signal.

16. The monitor of claim 15, wherein the one or more routines, when executed cause the processor to fit a line of best fit to the curve, to extract a gradient of the line, and to utilize the gradient of the line in normalizing the regional oxygen saturation signal to correct for variation in the oxygen saturation signal.

17. The monitor of claim 13, wherein the one or more routines, when executed cause the processor to normalize the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal only if a quality metric of a correlation between the oxygen saturation signal and the regional oxygen saturation is above a threshold value.

18. The monitor of claim 13, wherein the one or more routines, when executed cause the processor to normalize the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal only if an oxygen saturation value derived from the oxygen saturation signal falls below an oxygen saturation threshold value.

19. A system for monitoring autoregulation:

an oxygen saturation sensor configured to obtain an oxygen saturation signal from a patient;

a regional oxygen saturation sensor configured to obtain a regional oxygen saturation signal from a patient; and

a controller comprising a processor configured to execute one or more routines encoded on a memory that cause the controller to;

receive a blood pressure signal, the oxygen saturation signal, and the regional oxygen saturation signal from a patient;

normalize the regional oxygen saturation signal to correct for variation in the oxygen saturation signal based on a relationship between the oxygen saturation signal and the regional oxygen saturation signal;

determine a linear correlation between the blood pressure signal and the normalized regional oxygen saturation signal; and

provide a signal indicative of the patient'"'"'s autoregulation status to an output device based on the linear correlation.

20. The system of claim 19, comprising the output device, wherein the processor is configured to cause the output device to display a cerebral index value indicative of the patient'"'"'s autoregulation status, a normalized regional oxygen saturation value derived from the normalized regional oxygen saturation signal, a regional oxygen saturation value derived from the regional oxygen saturation signal and corresponding to the normalized regional oxygen saturation value, or any combination thereof.