Vector-based shock indication

• US 9,907,477 B2
• Filed: 07/18/2016
• Issued: 03/06/2018
• Est. Priority Date: 03/14/2014
• Status: Active Grant

• Current Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Original Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Inventors: Quan, Weilun, Freeman, Gary A.
• Primary Examiner(s): Johnson, Nicole F
• Application Number:
  US15/212,371
• Publication Number:
  US 20160338609A1
• Time in Patent Office: 596 Days
• Field of Search: 600508, 600510
• CPC Class Codes: A61B 5/0531 Measuring skin impedance
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/341 Vectorcardiography [VCG]
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/4848 Monitoring or testing the effects of treatment, e.g. of medication
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• 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: A61N 1/3925 Monitoring; Protecting
• CPC Class Codes: A61N 1/3987 characterised by the timing or triggering of the shock
• CPC Class Codes: A61N 1/3993 User interfaces for automatic external defibrillators
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A system for managing care of a person receiving emergency cardiac assistance includes one or more capacitors arranged to deliver a defibrillating shock to a person; one or more electronic ports for receiving a plurality of signals from sensors for obtaining indications of an electrocardiogram (ECG) for the person; and a patient treatment module executable on one or more computer processors using code stored in non-transitory media and to provide a determination of a likelihood of success from delivering a future defibrillating shock to the person with the one or more capacitors, using a mathematical computation applied to a vector value defined by signals from at least two of the plurality of signals.

Claims

1. A system for managing care of a person, the system comprising:

an external defibrillator, configured to monitor electrocardiogram (ECG) data from a person receiving emergency cardiac assistance, the ECG data defining a vector from multiple ECG signals; and

one or more processors configured to perform operations comprising;

performing a vectorized mathematical transform of the ECG data that defines the vector from a time domain to a frequency domain using a window in the time domain, determining a likelihood of future defibrillation shock success using at least the mathematical transformation, and

affecting control of the external defibrillator based on an identification of whether a present defibrillation shock will likely be effective.

2. The system of claim 1, wherein the mathematical transform comprises one or more vectorized Fast Fourier Transforms (FFTs).

3. The system of claim 2, wherein the mathematical transform comprises one or more amplitude spectrum area (AMSA) calculations.

4. The system of claim 1, the operations comprising applying a pre-transform to a plurality of signals before applying the mathematical transform so as to make the plurality of signals orthogonal or near orthogonal.

5. The system of claim 4, wherein the pre-transform is applied in response to determining that the plurality of signals were not previously orthogonal or near orthogonal.

6. The system of claim 5, the operations comprising applying the mathematical transform to the vector value by calculating FFT for each of the plurality of signals to create processed values, and then combining the processed values.

7. The system of claim 6, wherein combining the processed values comprises determining a root of a sum of the processed values.

8. The system of claim 1, wherein the mathematical transform comprises a transform from a time domain to a frequency domain on a window of data.

9. The system of claim 1, wherein the mathematical transform comprises a transform from a time domain to a frequency domain on a window of ECG data.

10. The system of claim 9, wherein the window comprises a tapered window.

11. The system of claim 10, wherein the tapered window comprises a Tukey window.

12. The system of claim 10, wherein the tapered window is between about one second and about two seconds wide.

13. The system of claim 10, wherein the tapered window is selected from a group consisting of Tukey, Hann, Blackman-Harris, and Flat Top.

14. The system of claim 9, wherein the mathematical transform comprises a Fast Fourier Transform.

15. The system of claim 1, wherein determining a likelihood of future defibrillation shock success comprises determining a value that is a function of electrocardiogram amplitude at particular different frequencies or frequency ranges.

16. The system of claim 15, wherein determining a likelihood of future defibrillation shock success comprises determining an amplitude spectrum area (AMSA) value for the ECG data.

17. The system of claim 16, wherein determining a likelihood of future defibrillation shock success further comprises adjusting the determined AMSA value using information about a prior defibrillation shock.

18. The system of claim 17, the operations comprising determining whether the adjusted AMSA value exceeds a predetermined threshold value.

19. The system of claim 18, the operations comprising providing to a rescuer a visual, audible, or tactile alert that a shockable situation exists for the person receiving emergency cardiac assistance, if the adjusted AMSA value is determined to exceed the predetermined threshold value.

20. The system of claim 1, the operations comprising determining whether a prior defibrillation shock was at least partially successful, and based at least in part on the determination of whether the prior defibrillation was at least partially successful, modifying a calculation of the likelihood of success from delivering the future defibrillating shock.

21. The system of claim 1, wherein determining a likelihood of success from delivering a future defibrillating shock comprises performing a calculation by an operation selected form a group consisting of logistic regression, table look-up, neural network, and fuzzy logic.

22. The system of claim 1, where the likelihood of success from delivering a future defibrillating shock is determined using at least one person-dependent physical parameter separate from a person ECG reading.

23. The system of claim 22, wherein the at least one person-dependent parameter comprises an indication of trans-thoracic impedance of the person receiving emergency cardiac care.

24. The system of claim 23, wherein the indication of trans-thoracic impedance is determined from signals sensed by a plurality of electrocardiogram leads that also provide the ECG data.

25. The system of claim 1, further comprising cyclically repeating the actions of monitoring, determining, identifying, and affecting the control.

26. The system of claim 1, the operations comprising identifying compression depth of chest compressions performed on the person receiving emergency cardiac assistance, using a device on the person'"'"'s sternum and in communication with the external defibrillator, and providing feedback to a rescuer performing the chest compressions, the feedback regarding rate of compression, depth of compression, or both.

27. The system of claim 1, wherein affecting control of the defibrillator comprises preventing a user from delivering a shock unless the determination of whether a shock will be effective exceeds a determined likelihood level.

28. The system of claim 1, wherein affecting control of the defibrillator comprises electronically displaying, to a user, an indicator of the determined indication of whether a shock will be effective.

29. The system of claim 28, wherein displaying an indicator comprises displaying a value, of multiple possible values in a range that indicates a likelihood of success.

30. The system of claim 29, wherein the calculation of the likelihood of current shock success is determined or modified using a determination of a value of trans-thoracic impedance of the person.

31. A non-transitory machine-readable storage defibrillation device for treating cardiac arrhythmia, the machine-readable storage device storing instructions that are executable by one or more processors to perform operations comprising:

acquiring electrocardiogram (ECG) signals from a person receiving emergency cardiac assistance;

determining an ECG vector representation of the plurality of ECG signals comprising at least two orthogonal or near orthogonal signals indicative of the ECG electrical vector of the person, wherein the ECG vector representation includes information of both magnitude and direction of the ECG electrical vector;

performing a mathematical transformation of the ECG vector representation from a time domain representation to a frequency domain representation of the ECG electrical vector;

determining a likelihood of shock success of delivering a defibrillating shock to the person with one or more capacitors based on the frequency domain representation; and

affecting control of an external defibrillator based on the determined likelihood of shock success.