Patent ID: 6044294
Filing Date: 2000-03-28
Classification: A61N

Abstract:
Apparatus implantable in a patient's body for determining the impedance of the patient's body, the apparatus being compatible with external devices which detect a desired body signal, the external device having second order low pass filtering characteristics corresponding to a second order integration of the desired body signal, comprising:impedance signal generating means for generating an impedance measurement signal having a series of substantially equally spaced multiphasic impedance measurement waveforms, each multiphasic impedance measurement waveform having a zero DC component and zero average after a first order integration by the external device, whereby the multiphasic waveform results in a zero value after the second order integration by the external device;means for applying the impedance measurement signal to the body and thus producing a resulting signal across the body;means for measuring the resulting signal; andmeans for determining the impedance of the body by analyzing the resulting signal.