Wearable cardioverter defibrillator (WCD) alarms

Patent metadata

Field	Value
Publication number	US-11160990-B1
Application number	US-201916382575-A
Country	US
Kind code	B1
Filing date	Apr 12, 2019
Priority date	Feb 14, 2018
Publication date	Nov 2, 2021
Grant date	Nov 2, 2021

Abstract

A wearable cardioverter defibrillator (WCD) comprises a plurality of electrocardiography (ECG) electrodes, a right-leg drive (RLD) electrode, and a plurality of defibrillator electrodes to contact the patient's skin when the WCD is delivering therapy to the patient, a preamplifier coupled to the ECG electrodes and the RLD electrode to obtain ECG data from the patient as one or more ECG vectors, a processor to receive ECG data from the preamplifier and an abort signal from a user interface, an isolation barrier to isolate the preamplifier from the processor, and a high voltage subsystem to provide a defibrillation voltage to the patient through the defibrillator electrodes in response to a shock signal received from the processor. A shock is provided when an abort signal is not received within a predetermined time period of a shock criterion being met. Less than one false alarm occurs every ten patient-days.

First claim

What is claimed is:

1. A wearable cardioverter defibrillator (WCD), comprising:
a plurality of electrocardiography (ECG) electrodes, a right-leg drive (RLD) electrode, and a plurality of defibrillator electrodes to contact the patient's skin when the WCD is delivering therapy to the patient;
a user interface;
a preamplifier coupled to the ECG electrodes and the RLD electrode to obtain ECG data from the patient as one or more ECG vectors;
a processor to receive ECG data from the preamplifier and an abort signal from the user interface;
an isolation barrier to isolate the preamplifier from the processor; and
a high voltage subsystem to provide a defibrillation voltage to the patient through the plurality of defibrillator electrodes in response to a shock signal received from the processor;
wherein the processor is to determine when a shock criterion is met based on the ECG data from the preamplifier, and to provide the shock signal in the event the shock criterion is met and the abort signal is not received within a predetermined time period of the shock criterion being met;
wherein the predetermined time period comprises a confirmation period when the shock criterion is met and the shock criterion is for ventricular fibrillation (VF) and wherein the predetermined time period comprises an extended confirmation period different from the confirmation period when the ECG data indicates the shock criterion is met and the shock criterion is for ventricular tachycardia (VT), the shock criterion for VT being different than the shock criterion for VF.

2. The WCD of claim 1 , wherein the processor is to determine QRS width data and heart rate data from the ECG data, and to determine when the shock criterion is met based on the QRS width data and the heart rate data.

3. The WCD of claim 1 , wherein the preamplifier includes one or more analog-to-digital converters (ADCs) to convert the ECG data into digitized ECG data that is provided across the isolation barrier to the processor.

4. The WCD of claim 1 , wherein the one or more vectors comprises four vectors.

5. The WCD of claim 1 , wherein the processor is to monitor the one or more ECG vectors, and is configured to determine when the shock criterion is met when one or more of the ECG vectors is noisy or when one or more of the plurality of ECG electrodes is in a lead-off condition.

6. The WCD of claim 1 , wherein the preamplifier is configured to receive the ECG data as differential signals using a voltage of the RLD electrode as a common mode signal or a common mode potential.

7. The WCD of claim 1 , wherein the preamplifier has a dynamic range at an input that is an order of magnitude or greater than a magnitude of the ECG data.

8. The WCD of claim 1 , wherein the ECG data received by the processor from the preamplifier is processed using one or more digital filters including a matched filter to determine QRS width data and/or heart rate data.

9. The WCD of claim 1 , wherein one or more of the plurality of ECG electrodes comprises a dry electrode to directly contact the patient's skin without using a gel or an adhesive.

10. The WCD of claim 1 , wherein one or more of the ECG electrodes comprises a silver disk, a silver plated copper disk, or a resistive electrode, or a combination thereof.

11. The WCD of claim 1 , wherein the processor is to process the ECG data received from the preamplifier in segments of ECG data, wherein the shock criterion is met when a string of a predetermined number of segments indicate a shock decision should be made.

12. The WCD of claim 1 , wherein the processor incurs less than one false alarm every ten patient-days indicating the shock criterion has been met.

13. The WCD of claim 12 , wherein a false alarm is due to an issue with contact of one or more of the plurality of ECG electrodes with the patient's skin.

14. The WCD of claim 1 , wherein, the extended confirmation period is used for VF when noise is detected in the ECG data.

15. A method to determine whether a defibrillation shock should be applied with a wearable cardioverter defibrillator (WCD), the method comprising:
receiving electrocardiography (ECG) data from a patient using the WCD with a preamplifier coupled to one or more ECG electrodes and a right-leg drive (RLD) electrode coupled to the patient's skin to obtain ECG data from the patient as one or more ECG vectors;
receiving ECG data from the preamplifier with a processor through an isolation barrier to electrically isolate the preamplifier from the processor;
determining with the processor if a shock criterion is met based on a combination of heart rate data and a width of one or more QRS pulses identified in the ECG data;
signaling the patient that the defibrillation shock is about to be applied; and
applying the defibrillation shock to the patient unless a stop shock signal is caused by the patient within a predetermined period of time after signaling the patient;
wherein the predetermined time period comprises a confirmation period when the shock criterion is met and the shock criterion is for ventricular fibrillation (VF) and wherein the predetermined time period comprises an extended confirmation period different from the confirmation period when the ECG data indicates the shock criterion is met and the shock criterion is for ventricular tachycardia (VT), the shock criterion for VT being different than the shock criterion for VF.

16. The method of claim 15 , further comprising identifying the one or more QRS pulses in the ECG data using a matched filter in the processor.

17. The method of claim 15 , further comprising processing the ECG data with the processor in segments of ECG data, wherein the shock criterion is met when a string of a predetermined number of segments indicate a shock decision should be made.

18. The method of claim 15 , further comprising incurring less than one false alarm every ten patient-days indicating the shock criterion has been met.

19. The method of claim 18 , wherein a false alarm is due to an issue with contact of one or more of the ECG electrodes with the patient's skin.

Assignees

• West Affum Holdings Corp

Inventors

• Sullivan Joseph L
• Finch David P
• Medema Douglas K
• Buchanan Robert R
• Kotlarchik Garrett M
• Kim Jaeho
• Cowan Kenneth F

Classifications

• A61B5/6805

  Vests, e.g. shirts or gowns · CPC title

• A61B5/363

  Detecting tachycardia or bradycardia · CPC title

• A61N1/3993

  User interfaces for automatic external defibrillators · CPC title

• A61N1/3987

  characterised by the timing or triggering of the shock · CPC title

• A61N1/39046 Primary

  User protection from shock · CPC title