Implantable medical devices evaluating thorax impedance
First Claim
1. An implantable medical device comprising:
- an impedance determination unit comprisinga constant current source or a constant voltage source having current feed terminals that are connected or can be connected to electrodes for intracorporal placement and that is configured to generate measuring current pulses having a constant current strength or a constant voltage, respectively, to cause a current to be fed through a body via intracorporally placed electrodes;
a measuring unit configured to measure a voltage corresponding to a current fed through a body by said constant current source or a current strength of a current fed through a body by said constant voltage source, respectively;
an impedance value determination unit that is connected to said constant current source or said constant voltage source and to the measuring unit wherein said impedance value determination unit is configured to determine an impedance value for each measuring current pulse; and
,an impedance measuring control and evaluation unit, that is connected to said impedance determination unit and that is configured to control said impedance determination unit and to evaluate a sequence of consecutive impedance values determined by said impedance determination unit; and
said impedance determination unit further configured todetermine at least intrathoracic impedance values and intracardiac impedance values concurrently, wherein the intrathoracic impedance values are sampled with a lower sampling rate than the intracardiac impedance values,determine respiration rate values from said intrathoracic impedance values,determine heart rate values from said intracardiac impedance values,evaluate said sequence of consecutive impedance values based on said respiration rate values and said heart rate values.
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Accused Products
Abstract
Implantable medical device with an impedance determination unit with constant current/voltage source having current feed terminals connected to electrodes for intracorporal placement which generates measuring current pulses having constant current/voltage, for causing a current through a body via intracorporally placed electrodes, a measuring unit for measuring voltage/current strength of voltage/current fed through body, an impedance value determination unit connected to the current/voltage source and adapted to determine an impedance value for each measuring current pulse, and an impedance measuring control and evaluation unit connected to the impedance determination unit which controls the unit and evaluates a sequence of consecutive impedance values, the impedance determination unit further adapted to determine at least intrathoracic and intracardiac impedance values for same period of time, the intrathoracic values sampled with a lower sampling rate than the intracardiac values.
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Citations
31 Claims
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1. An implantable medical device comprising:
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an impedance determination unit comprising a constant current source or a constant voltage source having current feed terminals that are connected or can be connected to electrodes for intracorporal placement and that is configured to generate measuring current pulses having a constant current strength or a constant voltage, respectively, to cause a current to be fed through a body via intracorporally placed electrodes; a measuring unit configured to measure a voltage corresponding to a current fed through a body by said constant current source or a current strength of a current fed through a body by said constant voltage source, respectively; an impedance value determination unit that is connected to said constant current source or said constant voltage source and to the measuring unit wherein said impedance value determination unit is configured to determine an impedance value for each measuring current pulse; and
,an impedance measuring control and evaluation unit, that is connected to said impedance determination unit and that is configured to control said impedance determination unit and to evaluate a sequence of consecutive impedance values determined by said impedance determination unit; and said impedance determination unit further configured to determine at least intrathoracic impedance values and intracardiac impedance values concurrently, wherein the intrathoracic impedance values are sampled with a lower sampling rate than the intracardiac impedance values, determine respiration rate values from said intrathoracic impedance values, determine heart rate values from said intracardiac impedance values, evaluate said sequence of consecutive impedance values based on said respiration rate values and said heart rate values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. An implantable medical device comprising:
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an impedance determination unit comprising a constant current source or a constant voltage source having current feed terminals that are connected or can be connected to electrodes for intracorporal placement and that is configured to generate measuring current pulses having a constant current strength or a constant voltage, respectively, to cause a current to be fed through a body via intracorporally placed electrodes; a measuring unit configured to measure a voltage corresponding to a current fed through a body by said constant current source or a current strength of a current fed through a body by said constant voltage source, respectively; an impedance value determination unit that is connected to said constant current source or said constant voltage source and to the measuring unit wherein said impedance value determination unit is configured to determine an impedance value for each measuring current pulse; and
,an impedance measuring control and evaluation unit, that is connected to said impedance determination unit and that is configured to control said impedance determination unit and to evaluate a sequence of consecutive impedance values determined by said impedance determination unit; said impedance determination unit further configured to determine at least intrathoracic impedance values and intracardiac impedance values concurrently, wherein the intrathoracic impedance values are sampled with a lower sampling rate than the intracardiac impedance values; said impedance measuring control and evaluation unit further configured to determine a respiratory rate from said intrathoracic impedance values and to use respiration rate values thus determined to further evaluate said sequence of consecutive impedance values; determine a heart rate from said intracardiac impedance values and to use heart rate values thus determined to further evaluate said sequence of consecutive impedance values; perform a population analysis based on said sequences of consecutive impedance values and determine population properties through analysis of a cluster of points in at least a three-dimensional space wherein a first dimension is given by a heart rate and a second dimension is given by an impedance and a third dimension is either a time of day or a respiratory rate and wherein each point of said cluster is determined by a triplet formed by a heart rate value, an impedance value and either a time of day value or a respiratory rate value.
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31. An implantable medical device comprising:
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an impedance determination unit comprising a constant current source or a constant voltage source having current feed terminals that are connected or can be connected to electrodes for intracorporal placement and that is configured to generate measuring current pulses having a constant current strength or a constant voltage, respectively, to cause a current to be fed through a body via intracorporally placed electrodes; a measuring unit configured to measure a voltage corresponding to a current fed through a body by said constant current source or a current strength of a current fed through a body by said constant voltage source, respectively; an impedance value determination unit that is connected to said constant current source or said constant voltage source and to the measuring unit wherein said impedance value determination unit is configured to determine an impedance value for each measuring current pulse; and
,an impedance measuring control and evaluation unit, that is connected to said impedance determination unit and that is configured to control said impedance determination unit and to evaluate a sequence of consecutive impedance values determined by said impedance determination unit; said impedance determination unit further configured to determine at least intrathoracic impedance values and intracardiac impedance values concurrently, wherein the intrathoracic impedance values are sampled with a lower sampling rate than the intracardiac impedance values; said impedance measuring control and evaluation unit further configured to compare a recent intrathoracic impedance value to a reference intrathoracic impedance value and to detect a decrease in thoracic fluid if said recent intrathoracic impedance value exceeds said reference intrathoracic impedance value, and compare a recent intrathoracic impedance value to a reference intrathoracic impedance value and to detect a change in thoracic fluid if said recent intrathoracic impedance value shows a corresponding change in said reference intrathoracic impedance value, and compare a recent intracardiac impedance value to a reference intracardiac impedance value and to detect a change in end-systolic volume if said recent intracardiac impedance value shows a corresponding change in said reference intracardiac impedance value, and compare a recent intracardiac impedance value to a reference intracardiac impedance value and to detect an increase in end-systolic volume if said recent intracardiac impedance value is smaller than said reference intracardiac impedance value, and analyse a modulation of a fiducial value in said intracardiac impedance Zcardiac by said intrathoracic impedance Zresp that corresponds to a cardiac function indication of a Frank-Starling curve, and determine absence, decompensation to, presence of, or resolution from heart failure as a prodromal or other confirmatory sign of lung edema.
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Specification