SYSTEM AND METHOD OF MONITORING AUTOREGULATION

• US 20170000423A1
• Filed: 06/27/2016
• Published: 01/05/2017
• Est. Priority Date: 06/30/2015
• Status: Active Grant

• Current Assignee: Covidien LP (Medtronic Plc)
• Original Assignee: Covidien LP (Medtronic Plc)
• Inventors: Addison, Paul S., Watson, James N.
• Granted Patent: US 10,292,663 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02255 the pressure being controlled by plethysmographic signals, e.g. derived from optical sensors
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• 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 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7235 Details of waveform analysis A61B5/349 takes precedence
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders

Abstract

A method for monitoring autoregulation includes receiving a blood pressure signal and an oxygen saturation signal, determining a phase difference between the blood pressure signal and the oxygen saturation signal, and determining a patient'"'"'s autoregulation status based at least in part on a phase difference between the blood pressure signal and the oxygen saturation signal.

Claims

1. A method for monitoring autoregulation comprising:

using a processor for;

receiving a blood pressure signal and an oxygen saturation signal;

determining a phase difference between the blood pressure signal and the oxygen saturation signal; and

determining a patient'"'"'s autoregulation status based at least in part on a phase difference between the blood pressure signal and the oxygen saturation signal.

2. The method of claim 1, comprising processing the blood pressure signal and the oxygen saturation signal using a complex transform to facilitate determination of the phase difference.

3. The method of claim 2, wherein the complex transform is a wavelet transform.

4. The method of claim 3, wherein the wavelet transform comprises a low oscillation Morlet wavelet with a central frequency of less than 5 radians per second.

5. The method of claim 2, comprising calculating a cross-wavelet transform of the blood pressure signal and the oxygen saturation signal, and synchrosqueezing the cross-wavelet transform to generate a synchrosqueezed cross-wavelet transform indicative of the phase difference.

6. The method of claim 1, comprising displaying a measure indicative of the patient'"'"'s autoregulation status.

7. The method of claim 1, comprising determining a cerebral oximetry index (COx) value based on the blood pressure signal and the oxygen saturation signal.

8. The method of claim 7, comprising determining a confidence level related to the COx value based on the phase difference.

9. The method of claim 7, comprising providing an indication of impaired autoregulation status to an output device while the COx value is greater than zero and the phase difference is approximately equal to zero.

10. The method of claim 7, comprising providing the COx value on a display while the COx value is zero or less than zero, and the phase difference is approximately +/−

π

radians, rapidly varying, and/or randomly distributed.

11. A non-transitory computer-readable medium having computer executable code stored thereon, the code comprising instructions to:

receive a blood pressure signal and an oxygen saturation signal;

determine a phase difference between the blood pressure signal and the oxygen saturation signal; and

determine a patient'"'"'s autoregulation status based at least in part on a phase difference between the blood pressure signal and the oxygen saturation signal.

12. The non-transitory computer-readable medium of claim 11, wherein the memory stores instructions for applying a cross-wavelet transform to the blood pressure signal and the oxygen saturation signal to determine the phase difference.

13. The non-transitory computer-readable medium of claim 11, wherein the memory stores instructions for determining a cerebral oximetry index (COx) value based on the blood pressure signal and the oxygen saturation signal.

14. The non-transitory computer-readable medium of claim 13, wherein the memory stores instructions for determining a confidence level related to the COx value based on the phase difference.

15. The non-transitory computer-readable medium of claim 14, wherein the memory stores instructions for providing an indication of impaired autoregulation status to an output device while the COx value is greater than zero and the phase difference is approximately equal to zero.

16. The non-transitory computer-readable medium of claim 11, wherein the memory stores instructions for calculating a cross-wavelet transform of the blood pressure signal and the oxygen saturation signal, and synchrosqueezing the cross-wavelet transform to generate a synchrosqueezed cross-wavelet transform indicative of the phase difference.

17. A system for monitoring autoregulation comprising:

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

a controller comprising a processor configured to;

receive a blood pressure signal and the oxygen saturation signal;

determine a phase difference between the blood pressure signal and the oxygen saturation signal; and

determine a patient'"'"'s autoregulation status based at least in part on a phase difference between the blood pressure signal and the oxygen saturation signal.

18. The system of claim 17, wherein the processor is configured to determine a cerebral oximetry index (COx) value based on the blood pressure signal and the oxygen saturation signal, and to determine a confidence level related to the COx value based on the phase difference.

19. The system of claim 18, wherein the processor is configured to provide an indication of the patient'"'"'s autoregulation status on a display.

20. The system of claim 17, wherein the processor is configured to calculate a cross-wavelet transform of the blood pressure signal and the oxygen saturation signal, synchrosqueeze the cross-wavelet transform to generate a synchrosqueezed cross-wavelet transform, and utilize the synchrosqueezed cross-wavelet transform to determine a confidence level related to the COx value.