System and method for identifying autoregulation zones

• US 10,219,705 B2
• Filed: 05/04/2016
• Issued: 03/05/2019
• Est. Priority Date: 05/08/2015
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Addison, Paul S., Montgomery, Dean
• Primary Examiner(s): Bertram, Eric D.
• Application Number:
  US15/146,595
• Publication Number:
  US 20160324425A1
• Time in Patent Office: 1,035 Days
• CPC Class Codes: A61B 5/02028 Determining haemodynamic parameters not otherwise provided for, e.g. cardiac contractility or left ventricular ejection fraction
• 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 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/4064 Evaluating the brain A61B5/031, A61B5/369, A61B5/14553 take precedence
• CPC Class Codes: A61B 5/6801 specially adapted to be attached to or worn on the body surface
• 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
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A method for monitoring autoregulation includes using a processor for receiving one or more physiological signals, determining a correlation-based measure indicative of the patient'"'"'s autoregulation based on the one or more physiological signals, calculating a data clustering metric indicative of a distribution of the correlation-based measure within a window of blood pressures, and determining whether the window of blood pressures is within an intact autoregulation zone or an impaired autoregulation zone based at least in part on the data clustering metric.

Claims

1. A method for monitoring autoregulation, the method comprising:

receiving, by a processor and from one or more sensors, a first physiological signal indicative of a blood pressure of a patient and a second physiological signal indicative of blood oxygen saturation of the patient;

determining, by the processor, a correlation-based measure indicative of the patient'"'"'s autoregulation based at least in part on the first physiological signal and the second physiological signal;

calculating, by the processor, a statistical data clustering metric indicative of two or more spreads of the correlation-based measure, each spread being within a respective window of blood pressures;

determining, by the processor, whether each window of blood pressures is within an intact autoregulation zone or an impaired autoregulation zone based at least in part on the data clustering metric; and

at least one of;

presenting, via a display, information indicative of a patient'"'"'s autoregulation status;

or

outputting, via an audio device, information indicative of the patient'"'"'s autoregulation status,

wherein the information indicative of the patient'"'"'s autoregulation status is based on the determination of whether each window of blood pressure is within the intact autoregulation zone or the impaired autoregulation zone.

2. The method of claim 1, wherein the data clustering metric comprises an entropy metric.

3. The method of claim 1, wherein the data clustering metric comprises a Mean Absolute Derivation.

4. The method of claim 1, wherein the data clustering metric comprises a sum of squares.

5. The method of claim 1, wherein the data clustering metric comprises at least one of a range, an interquartile range, or a variance.

6. The method of claim 1, wherein determining whether each window of blood pressures is within the intact autoregulation zone or the impaired autoregulation zone comprises comparing the data clustering metric to a predetermined threshold.

7. The method of claim 6, comprising, for at least one window of blood pressures, determining that blood pressures within the at least one window of blood pressures are within the intact autoregulation zone if the data clustering metric is greater than the predetermined threshold.

8. The method of claim 1, comprising, for at least one window of blood pressures, determining a quality level related to the determination of whether the at least one window of blood pressures is within the intact autoregulation zone or the impaired autoregulation zone based at least in part on a number of data points of the correlation-based measure utilized to calculate the data clustering metric for the at least one window of blood pressures.

9. The method of claim 1, comprising, for at least one window of blood pressures, determining which autoregulation zone encompasses the at least one window of blood pressures in less than approximately 15 minutes.

10. The method of claim 1, wherein the correlation-based measure includes at least one of a cerebral oximetry index, a hemoglobin volume index, a mean velocity index, or a pressure reactivity index.

11. The method of claim 1, comprising:

determining the autoregulation status of the patient based on the determination of whether each window of blood pressures is within the intact autoregulation zone or the impaired autoregulation zone.

12. A non-transitory computer-readable medium comprising computer executable code stored thereon, the code comprising instructions that, when executed by a processor, cause the processor to:

receive a blood pressure signal and an oxygen saturation signal;

determine a correlation-based measure indicative of the patient'"'"'s autoregulation based at least in part on the blood pressure signal and the oxygen saturation signal;

calculate a statistical data clustering metric indicative of two or more spreads of the correlation-based measure, each spread being within a respective window of blood pressures;

determine whether each window of blood pressures is within an intact autoregulation zone or an impaired autoregulation zone of a patient based at least in part on the data clustering metric; and

at least one of;

present, via a display, information indicative of a patient'"'"'s autoregulation status;

or

output, via an audio device, information indicative of the patient'"'"'s autoregulation status,

wherein the information indicative of the patient'"'"'s autoregulation status is based on the determination of whether each window of blood pressure is within the intact autoregulation zone or the impaired autoregulation zone.

13. The non-transitory computer-readable medium of claim 12, wherein the data clustering metric comprises at least one of an entropy metric, a range metric, a Mean Absolute Derivation metric, a sum of squares, an interquartile range, or a variance.

14. A system for monitoring autoregulation, the system comprising:

an oxygen saturation sensor configured to generate an oxygen saturation signal indicative of blood oxygen saturation of a patient; and

a controller comprising a processor configured to;

receive a blood pressure signal and the oxygen saturation signal;

determine a correlation-based measure indicative of the patient'"'"'s autoregulation based at least in part on the blood pressure signal and the oxygen saturation signal;

calculate a statistical data clustering metric indicative of two or more spreads of the correlation-based measure, each spread being within a respective window of blood pressures;

determine whether each window is associated with an intact autoregulation zone or an impaired autoregulation zone based at least in part on the data clustering metric; and

at least one of;

present, via a display, information indicative of a patient'"'"'s autoregulation status;

or

output, via an audio device, information indicative of the patient'"'"'s autoregulation status,

wherein the information indicative of the patient'"'"'s autoregulation status is based on the identification of whether each window of blood pressure is within the intact autoregulation zone or the impaired autoregulation zone.

15. The system of claim 14, wherein the data clustering metric comprises at least one of an entropy metric, a range metric, a Mean Absolute Derivation metric, a sum of squares, an interquartile range, or a variance.

16. The system of claim 14, wherein the processor is configured to:

determine the autoregulation status of the patient based on the determination of whether each window of blood pressures is associated with the intact autoregulation zone or the impaired autoregulation zone.

17. The system of claim 14, wherein the processor is configured to determine whether each window of blood pressures is within the intact autoregulation zone or the impaired autoregulation zone by at least comparing the data clustering metric to a predetermined threshold.

18. The system of claim 17, wherein the processor is configured to determine, for at least one window of blood pressures, that blood pressures within the at least one window of blood pressures are within the intact autoregulation zone if the data clustering metric is greater than the predetermined threshold.

19. The system of claim 14, wherein the processor is configured to determine, for at least one window of blood pressures, a quality level related to the determination of whether the at least one window of blood pressures is within the intact autoregulation zone or the impaired autoregulation zone based at least in part on a number of data points of the correlation-based measure utilized to calculate the data clustering metric for the at least one window of blood pressures.

20. The system of claim 14, wherein the processor is configured to determine, for at least one window of blood pressures, which autoregulation zone encompasses the at least one window of blood pressures in less than approximately 15 minutes.

21. The system of claim 14, wherein the correlation-based measure includes at least one of a cerebral oximetry index, a hemoglobin volume index, a mean velocity index, or a pressure reactivity index.