Patent ID: 7970462

Claim:
An implantable medical device comprising: 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.