Method and device for measuring subthreshold defibrillation electrode resistance and providing a constant energy shock delivery
First Claim
1. A method of controlling defibrillator operation including the step of measuring subthreshold defibrillation electrode resistance between two or more defibrillation electrodes, said measuring step further comprising the steps of sourcing a single subthreshold current pulse of predetermined magnitude across said electrodes, sampling the resulting voltage drop across said electrodes, subtracting low frequency noise and electrode polarization voltage artifacts from said resulting voltage drop to derive a defibrillation electrode voltage drop, measuring the voltage of said defibrillation electrode voltage drop, and calculating said resistance from said measured voltage and said predetermined magnitude of said current pulse.
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Accused Products
Abstract
A method and apparatus for measuring subthreshold defibrillation electrode resistance are disclosed. A known subthreshold current pulse is sourced across the electrodes, the resulting voltage is measured and the electrode resistance is calculated from these values. The calculated electrode resistance may be utilized to adjust the energy level of a defibrillation shock used to treat a detected tachyarrhythmia. In one embodiment the calculated resistance and a predetermined leading edge voltage are used to calculate and adjust the duration of the defibrillation shock. In another embodiment the calculated electrode resistance and a predetermined shock duration are used to adjust the leading edge voltage of the defibrillation shock.
203 Citations
47 Claims
- 1. A method of controlling defibrillator operation including the step of measuring subthreshold defibrillation electrode resistance between two or more defibrillation electrodes, said measuring step further comprising the steps of sourcing a single subthreshold current pulse of predetermined magnitude across said electrodes, sampling the resulting voltage drop across said electrodes, subtracting low frequency noise and electrode polarization voltage artifacts from said resulting voltage drop to derive a defibrillation electrode voltage drop, measuring the voltage of said defibrillation electrode voltage drop, and calculating said resistance from said measured voltage and said predetermined magnitude of said current pulse.
- 17. A method of providing a constant-energy defibrillation shock through two or more defibrillating electrodes, comprising the steps of detecting a tachyarrhythmia, sourcing a single subthreshold current pulse across said electrodes, measuring the resulting voltage, calculating the electrode resistance from the measured voltage and the current pulse magnitude, using said calculated electrode resistance to adjust the energy level of the defibrillation shock, and delivering said energy-level-adjusted defibrillation shock through said electrodes to treat said detected tachyarrhythmia.
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18. A method of providing a constant-energy defibrillation shock through two or more defibrillating electrodes, comprising the steps of detecting a tachyarrhythmia, sourcing a single subthreshold current pulse across said electrodes, measuring the resulting voltage, calculating the electrode resistance from the measured voltage and the current pulse magnitude, using the calculated electrode resistance and a predetermined leading edge voltage to calculate and adjust the duration of the defibrillation shock, and delivering a defibrillation shock through said electrodes to treat said detected tachyarrhythmia.
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19. A method of providing a constant-energy defibrillation shock through two or more defibrillating electrodes, comprising the steps of detecting a tachyarrhythmia, sourcing a single subthreshold current pulse across said electrodes, measuring the resulting voltage, calculating the electrode resistance from the measured voltage and the current pulse magnitude, using the calculated electrode resistance and a predetermined shock duration to adjust the leading edge voltage of the defibrillation shock, and delivering a defibrillation shock through said electrodes to treat said detected tachyarrhythmia.
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20. A method of providing a parameter for the control of defibrillation threshold tracking utilizing two or more defibrillating electrodes, comprising the steps of detecting a tachyarrhythmia, sourcing a single subthreshold current pulse across said electrodes, measuring the resulting voltage, calculating the electrode resistance from said measured voltage and the magnitude of said current pulse, comparing said calculated electrode resistance with the last resistance value so-calculated, adjusting the energy level of the defibrillation shock to a maximum value if said last resistance value is exceeded by a specified amount, and delivering said maximum defibrillation shock through said electrodes to treat said detected tachyarrhythmia.
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29. A defibrillation device for reverting tachyarrhythmia in a patient'"'"'s heart, said device including means for detecting a tachyarrhythmia condition in the heart, and means including two or more defibrillation electrodes and a source of defibrillation shock voltage for delivering defibrillation shock therapy through said electrodes to the heart, said device further including circuitry for measuring the resistance between said defibrillation electrodes, comprising:
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means independent of said defibrillation shock voltage and adapted to be coupled to said defibrillation electrodes for a first predetermined period of time for sourcing a single subthreshold current pulse of predetermined magnitude across said electrodes during said predetermined period of time; means adapted to be coupled to said electrodes for sampling the resultant voltage drop across the electrodes; means for subtracting low frequency noise and electrode polarization artifacts from said resulting voltage drop to derive a defibrillation electrode voltage drop; means for measuring the voltage of said defibrillation electrode voltage drop; and
,means for calculating said resistance from said measured voltage and said current pulse magnitude. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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30. A defibrillation device for providing a constant-energy defibrillation shock to revert tachyarrhythmia in a patient'"'"'s heart, said device including means for detecting a tachyarrhythmia condition in the heart, means including two or more defibrillation electrodes and a source of defibrillation shock voltage for delivering defibrillation shock therapy through said electrodes to the heart, and a circuit for measuring the resistance between said defibrillation electrodes, said device further comprising:
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means for switching said defibrillation electrodes into communication with said resistance measuring circuit; means operative during a first predetermined time period for sourcing a single subthreshold current pulse of predetermined magnitude from said resistance measuring circuit across said electrodes; means for measuring the resultant voltage drop; means for calculating the defibrillation electrode resistance from the measured voltage drop and the current pulse magnitude; and
,means responsive to said calculated electrode resistance and operative to adjust the energy-level of said defibrillation shock for delivering said energy-level-adjusted defibrillation shock through said electrodes to treat said tachyarrhythmia.
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31. A defibrillation device for providing a constant-energy defibrillation shock to revert tachyarrhythmia in a patient'"'"'s heart, said device including means for detecting a tachyarrhythmia condition in the heart, means including two or more defibrillation electrodes and a source of defibrillation shock voltage for delivering defibrillation shock therapy through said electrodes to the heart, and a circuit for measuring the resistance between said defibrillation electrodes, said device further comprising:
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means for switching said defibrillation electrodes into communication with said resistance measuring circuit; means operative during a first predetermined time period for sourcing a single subthreshold current pulse of predetermined magnitude from said resistance measuring circuit across said electrodes; means for measuring the resultant voltage drop; means for calculating the defibrillation electrode resistance from the measured voltage drop and the current pulse magnitude; and
,means responsive to said calculated electrode resistance and to a predetermined leading edge voltage of said defibrillation shock, and operative to calculate and adjust the duration of said defibrillation shock, for delivering said duration-adjusted defibrillation shock through said electrodes to treat said detected tachyarrhtyhmia.
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32. A defibrillation device for providing a constant-energy defibrillation shock to revert tachyarrhythmia in a patient'"'"'s heart, said device including means for detecting a tachyarrhythmia condition in the heart, means including two or more defibrillation electrodes and a source of defibrillation shock voltage for delivering defibrillation shock therapy through said electrodes to the heart, and a circuit for measuring the resistance between said defibrillation electrodes, said device further comprising:
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means for switching said defibrillation electrodes into communication with said resistance measuring circuit; means operative during a first predetermined time period for sourcing a single subthreshold current pulse of predetermined magnitude from said resistance measuring circuit across said electrodes; means for measuring the resultant voltage drop; means for calculating the defibrillation electrode resistance from the measured voltage drop and the current pulse magnitude; and
,means responsive to said calculated electrode resistance and to a predetermined defibrillation shock duration, and operative to adjust the leading edge voltage of said defibrillation shock, for delivering said leading-edge-voltage-adjusted defibrillation shock through said electrodes to treat said detected tachyarrhythmia.
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33. A device for providing a defibrillation shock to revert tachyarrhythmia in a patient'"'"'s heart, said device having a parameter for the control of defibrillation threshold tracking, and including means for detecting a tachyarrhythmia condition in the heart, means including two or more defibrillation electrodes and a source of defibrillation shock voltage for delivering defibrillation shock therapy through said electrodes to the heart, and a circuit for measuring the resistance between said defibrillation electrodes, said device further comprising:
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means for switching said defibrillation electrodes into communication with said resistance measuring circuit; means operative during a first predetermined time period for sourcing a single subthreshold current pulse of predetermined magnitude from said resistance measuring circuit across said electrodes, means for measuring the resultant voltage drop; means for calculating the defibrillation electrode resistance from the measured voltage drop and the current pulse magnitude; means for comparing the calculated electrode resistance to the last resistance value so-calculated; and
,means responsive to said comparison and operative to adjust the energy level of the defibrillation shock to a maximum value when said calculated resistance exceeds by a predetermined amount said last resistance value so-calculated, for delivering said maximum defibrillation shock through said electrodes to treat said detected tachyarrhythmia.
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Specification