Fast identification of shockable or non-shockable rhythms in ECG data
Methods and systems that analyze electrocardiogram (ECG) data to identify whether it would be beneficial for a caregiver to administer an electric shock to the heart in an effort to get the heart back into a normal pattern and a consistent, strong beat. By conducting a running check for conditions that are pre-validated by a comprehensive patient database to have high predictive value (e.g., with a low false-positive rate), a shockable rhythm can be identified fast (e.g., less than 6 seconds, less than 3 seconds, possibly in less than a second) and without having to analyze ECG data for longer time segments than would otherwise be required using conventional methods.
1. A defibrillator comprising:
one or more capacitors for delivering a defibrillating shock to a patient;
one or more electronic ports for receiving signals from at least one sensor for obtaining indications of an electrocardiogram (ECG) for the patient;
a patient treatment circuit executable on one or more processing devices configured for:
receiving data representing an ECG signal,
processing a variable-length time segment of the ECG signal comprising an initial time period, wherein the processing comprises
identifying one or more features of the variable-length time segment based on an initial rule set corresponding to the initial time period, for determining whether an ECG rhythm represented by the ECG signal is shockable or non-shockable,
based on the initial rule set, determining whether the ECG rhythm represented by the ECG signal is shockable or non-shockable or whether to extend the variable-length time segment for further analysis,
extending the initial time period of the variable-length time segment by one or more additional time periods,
identifying one or more features of the variable-length time segment based on an adjusted rule set corresponding to an adjusted time period, for updating the determination of whether the ECG rhythm is shockable or non-shockable; and
a delivery circuit configured to deliver a treatment to the patient based on the determination.
2. The defibrillator of claim 1 wherein the initial time period is between 0.1 second and approximately 3 seconds.
3. The defibrillator of claim 1 wherein extending the variable-length time segment comprises extending the variable-length time segment by an additional time period of between 0.1 second and approximately 3 seconds.
4. The defibrillator of claim 1 wherein the determination of whether the ECG rhythm is shockable or non-shockable is made after processing the variable-length time segment of the ECG signal for less than 6 seconds.
5. The defibrillator of claim 1 wherein the length of the time segment being processed varies based on identity of the one or more features being used to make the determination of whether the ECG rhythm is shockable or non-shockable.
6. The defibrillator of claim 1 wherein the processing comprises identifying whether an interruption in chest compressions has occurred, and analyzing the variable-length time segment of the ECG signal during the chest compression interruption according to the initial rule set.
7. The defibrillator of claim 6 wherein identifying whether the interruption in chest compressions has occurred comprises processing signals produced from at least one of an ECG electrode and a motion sensor.
8. The defibrillator of claim 1 wherein the initial rule set includes one or more clauses representing constraints on one or more features of the ECG signal, each of the one or more features of the ECG signal representing a characteristic of a waveform of the ECG signal within the variable-length time segment.
9. The defibrillator of claim 1 wherein the processing comprises analyzing the variable-length time segment of the ECG signal during chest compressions according to a continuous analysis rule set prior to the initial time period.
10. The defibrillator of claim 9 wherein the analyzing the variable-length time segment of the ECG signal during chest compressions according to the continuous analysis rule set occurs prior to identifying whether an interruption in chest compressions has occurred.
11. The defibrillator of claim 10 wherein determining whether the ECG rhythm represented by the ECG signal is shockable or non-shockable comprises comparing analysis of the ECG signal during the chest compression interruption according to the initial rule set with analysis of the ECG signal during chest compressions according to the continuous analysis rule set.
12. The defibrillator of claim 1 wherein the one or more processing devices are configured for storing the ECG data in a buffer configured to hold data representing the variable-length time segment of the ECG signal.
13. The defibrillator of claim 1 wherein the one or more processing devices are configured for causing the one or more capacitors to begin a charging sequence if the ECG rhythm is determined to be shockable.
14. The defibrillator of claim 1 , comprising an output circuit that is configured to present a user interface configured for providing feedback indicating if the ECG rhythm is shockable or non-shockable.
15. The defibrillator of claim 1 , wherein the initial rule set includes at least one high accuracy clause and the adjusted rule set includes at least one clause different from the at least one high accuracy clause.
16. The defibrillator of claim 1 , wherein the adjusted rule set employs a voting scheme that divides the variable-length time segment into a plurality of voting segments, each voting segment providing a voting determination of whether the ECG rhythm represented by the ECG signal during the respective voting segment is shockable or non-shockable.
17. The defibrillator of claim 16 , wherein the determination of whether the ECG rhythm is shockable or non-shockable is based on the voting determination of the plurality of voting segments.
18. The defibrillator of claim 1 , wherein the defibrillator comprises a wearable ambulatory medical device including a garment configured to:
be worn about a torso of the patient for an extended period of time,
support one or more components of the defibrillator, and
receive at least one ECG sensing electrode for sensing the ECG signal of the patient and at least one therapy electrode for providing a therapeutic shock to the patient.
19. The defibrillator of claim 1 , wherein the defibrillator is configured to substantially continuously monitor the ECG signal of the patient and provide a therapeutic shock on detecting a shockable ECG rhythm.
20. The defibrillator of claim 1 , wherein extending the variable-length time segment comprises extending the variable-length time segment by an additional time period of between 0.1 and 2 seconds.
21. A defibrillator comprising:
one or more capacitors for delivering a defibrillating shock to a patient;
one or more electronic ports for receiving signals from at least one sensor for obtaining indications of an electrocardiogram (ECG) for the patient;
a patient treatment circuit executable on one or more processing devices configured for:
receiving data representing an ECG signal,
processing a variable-length time segment of the ECG signal comprising an initial time period of between 0.1 second and approximately 3 seconds, the initial time period, wherein the processing comprises
identifying whether an interruption in chest compressions has occurred,
analyzing the variable-length time segment of the ECG signal during the chest compression interruption according to an initial rule set based on the initial time period, for determining whether an ECG rhythm represented by the ECG signal is shockable or non-shockable,
based on the initial rule set, determining whether the ECG rhythm represented by the ECG signal is shockable or non-shockable or whether to extend the variable-length time segment for further analysis,
generating an output based on the determination of whether the ECG rhythm represented by the ECG signal is shockable or non-shockable; and
a delivery circuit configured to deliver a treatment to the patient based on the determination.
22. The defibrillator of claim 21 wherein identifying whether the interruption in chest compressions has occurred comprises processing signals produced from at least one of an ECG electrode and a motion sensor.
23. The defibrillator of claim 21 wherein the initial rule set includes one or more clauses representing constraints on one or more features of the ECG signal, each of the one or more features of the ECG signal representing a characteristic of a waveform of the ECG signal within the variable-length time segment.
24. The defibrillator of claim 23 wherein the patient treatment circuit is configured for generating a prompt instructing a user to stop CPR chest compressions, and wherein identifying the chest compression interruption occurs after generating the prompt instructing the user to stop CPR chest compressions.
25. The defibrillator of claim 24 , wherein the patient treatment circuit is configured for generating a subsequent prompt instructing a user to stop CPR chest compressions based on whether the chest compression interruption has been identified.
26. The defibrillator of claim 21 wherein analyzing the variable-length time segment of the ECG signal occurs approximately 1.5 seconds or less after identifying the chest compression interruption.
27. The defibrillator of claim 21 wherein the processing comprises analyzing the variable-length time segment of the ECG signal during chest compressions according to a continuous analysis rule set prior to the initial time period, and prior to identifying whether the interruption in chest compressions has occurred.
28. The defibrillator of claim 27 wherein determining whether the ECG rhythm represented by the ECG signal is shockable or non-shockable comprises comparing analysis of the ECG signal during the chest compression interruption according to the initial rule set with analysis of the ECG signal during chest compressions according to the continuous analysis rule set.
29. The defibrillator of claim 21 comprising extending the initial time period of the variable-length time segment by one or more additional time periods, and analyzing the variable-length time segment based on an adjusted rule set corresponding to an adjusted time period, for updating the determination of whether the ECG rhythm is shockable or non-shockable.
30. The defibrillator of claim 21 , wherein the comprising an output circuit that is configured to present a user interface configured for providing feedback indicating if the ECG rhythm is shockable or non-shockable.
31. The defibrillator of claim 21 , wherein the defibrillator comprises an ambulatory medical device including a garment configured to:
be worn about a torso of the patient for an extended period of time,
support one or more components of the defibrillator, and
receive at least one ECG sensing electrode for sensing the ECG signal of the patient and at least one therapy electrode for providing a therapeutic shock to the patient.
32. The defibrillator of claim 21 , wherein analyzing the variable-length time segment of the ECG signal occurs approximately 0.5 seconds or less after identifying the chest compression interruption.