SYSTEMS AND METHODS FOR MEASURING ELECTROMECHANICAL DELAY OF THE HEART

• US 20110245690A1
• Filed: 03/31/2010
• Published: 10/06/2011
• Est. Priority Date: 03/31/2010
• Status: Active Grant

• Current Assignee: Nellcor Puritan Bennett Ireland
• Original Assignee: Nellcor Puritan Bennett Ireland
• Inventors: Addison, Paul Stanley, Watson, James N., Stoughton, Robert
• Granted Patent: US 9,451,887 B2
• Time in Patent Office: Days
• US Class Current: 600/485
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/6814 Head
• CPC Class Codes: A61B 5/6816 Ear lobe
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6826 Finger

Abstract

Systems and methods are disclosed herein for measuring the electromechanical delay of the heart of a patient. An electrocardiogram (EKG) signal may be used to detect heart electrical activity. Photoplethysmograph (PPG) signals may be used to detect heart mechanical activity. The electromechanical delay may be calculated based at least in part on the timing of an EKG signal and at least two PPG signals.

Claims

1. A system for measuring electromechanical delay of the heart of a patient, the system comprising:

at least two PPG sensors attached to the patient for generating at least two PPG signals;

an EKG sensor attached to the patient for generating an EKG signal;

a processor coupled to the at least two PPG sensors and the EKG sensor, wherein the processor is capable of;

determining at least one differential pulse transit time (DPTT) value based at least in part on the at least two PPG signals,

determining at least one EKG to PPG transit time value based at least in part on the EKG signal and one of the at least two PPG signals,

calculating an electromechanical delay value based at least in part on the determined DPTT value and the determined EKG to PPG transit time value; and

an output device coupled to the processor.

2. The system of claim 1, wherein the EKG to PPG transit time values comprise a substantially constant electromechanical delay component and a variable pulse transit time component, wherein the variable pulse transit time component scales substantially linearly with DPTT.

3. The system of claim 2, wherein the relationship between the EKG to PPG transit time and DPTT is

E=A·

T+D

or a mathematical equivalent thereof, wherein E is an EKG to PPG transit time value, T is a DPTT value, D is the electromechanical delay value, and A is a constant.

4. The system of claim 1, wherein the processor is further capable of:

determining a further EKG to PPG transit time value based at least in part on the EKG signal and a second PPG signal; and

calculating an electromechanical delay value based at least in part on the determined DPTT value and the further EKG to PPG transit time value.

5. The system of claim 4, wherein the processor is further capable of calculating an electromechanical delay value based at least in part on the determined DPTT value and the EKG to PPG transit time values determined from the first and the second PPG signals.

6. The system of claim 1, wherein the processor is further capable of assessing a condition of the patient'"'"'s heart based at least in part on the electromechanical delay value.

7. The system of claim 6, wherein the processor is further capable of:

monitoring the electromechanical delay value over time;

determining a change in the electromechanical delay value; and

triggering the output device to generate an alert.

8. The system of claim 1, wherein the processor is further capable of calculating a blood pressure value of the patient based on at least one of:

(a) the differential pulse transit time values and (b) the electromechanical delay value and EKG to PPG transit time values.

9. The system of claim 8, wherein the processor is further capable of:

detecting a signal degradation of at least one PPG signal; and

calculating a blood pressure value of the patient based on the electromechanical delay value and EKG to PPG transit time values from at least one other PPG signal in response to detecting the signal degradation.

10. A method for measuring electromechanical delay of the heart of a patient, the method comprising:

obtaining at least two PPG signals from at least two respective PPG sensors attached to the patient;

obtaining an EKG signal from an EKG sensor attached to the patient;

determining at least one differential pulse transit time (DPTT) value based at least in part on the at least two PPG signals;

determining at least one EKG to PPG transit time value based at least in part on the EKG signal and one of the at least two PPG signals; and

calculating an electromechanical delay value based at least in part on the determined DPTT values and the determined EKG to PPG transit time value.

11. The method of claim 10, wherein the EKG to PPG transit time values comprise a substantially constant electromechanical delay component and a variable pulse transit time component, wherein the variable pulse transit time component scales substantially linearly with DPTT.

12. The method of claim 11, wherein the relationship between the EKG to PPG transit time and DPTT is

E=A·

T+D

or a mathematical equivalent thereof, wherein E is an EKG to PPG transit time value,

T is a DPTT value, D is the electromechanical delay value, and A is a constant.

13. The method of claim 10, further comprising:

determining a further EKG to PPG transit time value based at least in part on the EKG signal and a second PPG signal; and

calculating an electromechanical delay value based at least in part on the determined DPTT value and the further EKG to PPG transit time value.

14. The method of claim 13, further comprising calculating an electromechanical delay value based at least in part on the determined DPTT value and the EKG to PPG transit time values determined from the first and the second PPG signals.

15. The method of claim 10, further comprising assessing a condition of the patient'"'"'s heart based at least in part on the electromechanical delay value.

16. The method of claim 15, further comprising:

monitoring the electromechanical delay value over time;

determining a change in the electromechanical delay value; and

triggering the output device to generate an alert.

17. The method of claim 10, further comprising calculating a blood pressure value of the patient based on at least one of:

(a) the differential pulse transit time values and (b) the electromechanical delay value and EKG to PPG transit time values.

18. The method of claim 17, further comprising:

detecting a signal degradation of at least one PPG signal; and

calculating a blood pressure value of the patient based on the electromechanical delay value and EKG to PPG transit time values from at least one other PPG signal in response to detecting the signal degradation.

19. A computer-readable medium for use in measuring electromechanical delay of the heart of a patient, the computer-readable medium having computer program instructions recorded thereon for:

obtaining at least two PPG signals from at least two respective PPG sensors attached to the patient;

obtaining an EKG signal from an EKG sensor attached to the patient;

determining at least one differential pulse transit time (DPTT) value based at least in part on the at least two PPG signals;

determining at least one EKG to PPG transit time value based at least in part on the EKG signal and one of the at least two PPG signals; and

calculating an electromechanical delay value based at least in part on the determined DPTT value and EKG to PPG transit time value.