ECG rhythm advisory method

• US 7,565,194 B2
• Filed: 05/12/2004
• Issued: 07/21/2009
• Est. Priority Date: 05/12/2004
• Status: Expired due to Fees

• Current Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Original Assignee: Zoll Medical Corporation (Asahi Kasei Corporation)
• Inventors: Freeman, Gary A., Tan, Qing, Brewer, James E., Geheb, Frederick
• Primary Examiner(s): Layno; Carl H
• Assistant Examiner(s): Gedeon; Brian T
• Application Number:
  US10/844,253
• Publication Number:
  US 20050256415A1
• Time in Patent Office: 1,896 Days
• Field of Search: 600508-509, 600/513, 600/515, 600/518, 607/2, 607/5, 607/9
• US Class Current: 607/2
• CPC Class Codes: A61B 5/347 Detecting the frequency distribution of signals
• CPC Class Codes: A61B 5/361 Detecting fibrillation
• CPC Class Codes: A61B 5/363 Detecting tachycardia or bradycardia
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61H 2201/5015 using specific interfaces or standards, e.g. USB, serial, parallel
• CPC Class Codes: A61H 2230/04 Heartbeat characteristics, e.g. E.G.C., blood pressure modulation
• CPC Class Codes: A61H 31/005 with feedback for the user
• CPC Class Codes: A61N 1/39 Heart defibrillators
• CPC Class Codes: A61N 1/3904 External heart defibrillators [EHD]
• CPC Class Codes: A61N 1/39044 in combination with cardiopulmonary resuscitation [CPR] therapy
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising transforming one or more time domain electrocardiogram (ECG) signals into a frequency domain representation comprising a plurality of discrete frequency bands, combining the discrete frequency bands into a plurality of analysis bands, wherein there are fewer analysis bands than discrete frequency bands,

determining the content of the analysis bands, and determining the type of treatment based on the content of the analysis bands.

Claims

1. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

transforming one or more time domain ECG signals into a frequency domain generally containing a plurality of peaks;

processing the frequency domain representation to characterize at least a plurality of the peaks, wherein the plurality of parameters constitute less than the full frequency domain representation of the peak, wherein characterizing a peak comprises determining a plurality of parameters characterizing the peak;

determining a reference frequency from the frequency domain;

determining a variance of the energy of the frequency domain using the reference frequency;

determining that the victim is in a sinus arrhythmic state if the variance of the energy of the frequency representation is below a threshold, and

determining the type of treatment based on the parameters characterizing at least some of the peaks, wherein determining the type of treatment comprises determining that the type of treatment is to defibrillate the victim'"'"'s heart if the following conditions are met;

the victim is determined to be in the sinus arrhythmic state;

a frequency of a largest amplitude frequency peak is less than a first threshold; and

the number of peaks is less than a second threshold.

2. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

transforming one or more time domain ECG signals into a frequency domain generally containing a plurality of peaks;

processing the frequency domain representation to characterize at least a plurality of the peaks, wherein the plurality of parameters constitute less than the full frequency domain representation of the peak, wherein characterizing a peak comprises determining a plurality of parameters characterizing the peak;

determining a reference frequency from the frequency domain,

determining a variance of the energy of the frequency domain using the reference frequency;

determining that the victim is in a sinus arrhythmic state if the variance of the energy of the frequency representation is below a threshold, and

determining the type of treatment based on the parameters characterizing at least some of the peaks, wherein determining the type of treatment comprises determining that the type of treatment is chest compressions to the victim if the following conditions are met;

the victim is determined to be in the sinus arrhythmic state; and

a frequency of a largest amplitude frequency peak is greater than a first threshold and if the number of peaks is less than a second threshold.

3. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

transforming one or more time domain ECG signals into a frequency domain generally containing a plurality of peaks;

processing the frequency domain representation to characterize at least a plurality of the peaks, wherein the plurality of parameters constitute less than the full frequency domain representation of the peak, wherein characterizing a peak comprises determining a plurality of parameters characterizing the peak; and

determining the type of treatment based on the parameters characterizing at least some of the peaks,

wherein determining parameters comprises measuring a change of one or more parameters of the peaks in a range of a frequency spectrum over multiple digital time samples,

wherein the plurality of the peaks comprise a largest amplitude frequency peak and peaks having a fraction of an amplitude of the largest amplitude frequency peak,

wherein the parameters comprise a frequency of a peak, an amplitude of the peak, and a width of the peak, and

wherein determining the type of treatment comprises comparing an oscillation cycle rate of the change to a cycle rate band and if the cycle rate is in the band, determining that the type of treatment is to defibrillate the victim'"'"'s heart.

4. The method of claim 3 wherein determining the type of treatment further comprises determining that a defibrillating shock to the victim'"'"'s heart is suitable therapy when the oscillation is at or near a maximum.

5. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

transforming one or more time domain ECG signals into a frequency domain generally containing a plurality of peaks;

processing the frequency domain representation to characterize at least a plurality of the peaks, wherein the plurality of parameters constitute less than the full frequency domain representation of the peak, wherein characterizing a peak comprises determining a plurality of parameters characterizing the peak; and

determining the type of treatment based on the parameters characterizing at least some of the peaks,

wherein determining parameters comprises measuring a change of one or more parameters of the peaks in a range of a frequency spectrum over multiple digital time samples,

wherein the plurality of the peaks comprise a largest amplitude frequency peak and peaks having a fraction of an amplitude of the largest amplitude frequency peak,

wherein the parameters comprise a frequency of a peak, an amplitude of the peak, and a width of the peak, and

wherein, for two or more peaks the change is a relative decrease, and wherein determining the type of treatment comprises comparing the relative decrease to a threshold, and if the relative decrease is above the threshold, the type of treatment is chest compressions and then defibrillation.

6. The method of claim 5 wherein the one or more parameters comprises amplitudes of the peaks, the threshold is about fifteen percent, and the multiple digital time samples cover at least a ten second interval.

7. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

transforming one or more time domain ECG signals into a frequency domain generally containing a plurality of peaks;

processing the frequency domain representation to characterize at least a plurality of the peaks, wherein the plurality of parameters constitute less than the full frequency domain representation of the peak, wherein characterizing a peak comprises determining a plurality of parameters characterizing the peak; and

determining the type of treatment based on the parameters characterizing at least some of the peaks,

wherein determining parameters comprises measuring a change of one or more parameters of the peaks in a range of a frequency spectrum over multiple digital time samples,

wherein the plurality of the peaks comprise a largest amplitude frequency peak and peaks having a fraction of an amplitude of the largest amplitude frequency peak,

wherein the parameters comprise a frequency of a peak, an amplitude of the peak, and a width of the peak, and

wherein, for two or more peaks, the change is a relative increase, the parameters comprise frequency of the peaks, amplitude of the peaks, or width of the peaks, and wherein determining the type of treatment comprises comparing the relative increase to a threshold, and if the relative increase is above the threshold, the type of treatment is defibrillation.

8. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

transforming one or more time domain ECG signals into a frequency domain generally containing a plurality of peaks;

processing the frequency domain representation to characterize at least a plurality of the peaks, wherein the plurality of parameters constitute less than the full frequency domain representation of the peak, wherein characterizing a peak comprises determining a plurality of parameters characterizing the peak; and

determining the type of treatment based on the parameters characterizing at least some of the peaks,

wherein determining parameters comprises measuring a change of one or more parameters of the peaks in a range of a frequency spectrum over multiple digital time samples,

wherein the plurality of the peaks comprise a largest amplitude frequency peak and peaks having a fraction of an amplitude of the largest amplitude frequency peak,

wherein the parameters comprise a frequency of a peak, an amplitude of the peak, and a width of the peak, and for two or more peaks, the change is a decrease, and the parameters comprise variance of the frequency of the peaks, and wherein determining the type of treatment comprises comparing the decrease to a threshold, and if the decrease is below a threshold, the type of treatment is defibrillation.

9. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

transforming one or more time domain ECG signals into a frequency domain generally containing a plurality of peaks;

processing the frequency domain representation to characterize at least a plurality of the peaks, wherein the plurality of parameters constitute less than the full frequency domain representation of the peak, wherein characterizing a peak comprises determining a plurality of parameters characterizing the peak; and

determining the type of treatment based on the parameters characterizing at least some of the peaks,

wherein determining parameters comprises measuring a change of one or more parameters of the peaks in a range of a frequency spectrum over multiple digital time samples,

wherein the plurality of the peaks comprise a largest amplitude frequency peak and peaks having a fraction of an amplitude of the largest amplitude frequency peak,

wherein the parameters comprise a frequency of a peak, an amplitude of the peak, and a width of the peak, and

wherein the range of the frequency spectrum is six to twelve Hertz.

10. A method of automatically determining which type of treatment is most appropriate for a cardiac arrest victim, the method comprising:

relying on a ventricular fibrillation (VF) or a ventricular tachycardia (VT) advisory algorithm to determine whether the victim is in VF or VT, and

determining when to deliver a shock to a victim that is in VF or VT by;

transforming one or more time domain ECG signals into a frequency domain representation;

processing the frequency domain representation to characterize the content of the frequency domain representation in a band from about 6 to about 12 Hz; and

determining when to deliver a shock based on the content in the about 6 to about 12 Hz band.

11. The method of claim 10 wherein the content in the band comprises a quantitative measure representative of approximately the total energy in the band.