Patent Number:
6,253,103
Title:
Method and apparatus for high current electrode, transthoracic and transmyocardial impedance estimation
Abstract:
Impedance across a load, such as a pair of face-to-face electrodes and/or a patient's transthoracic and transmyocardial impedance, respectively, is modeled as a resistor in series with a capacitor, wherein the reactance component of the impedance equals 2.pi.*frequency/capacitance. A reference square wave voltage is applied to the load in series with a selected load resistor, and a response voltage is measured across the load. Both the reference voltage and the response voltage are then used to estimate a transfer function between them. Equating this transfer function to a resistor-capacitor circuit model results in estimation of the actual resistance and capacitance components of the true impedance. Alternately, the impedance may be measured with a high current load, such as during a defibrillator discharge. In this case, the voltage input and outputs are sampled at a much faster rate for the resistance component estimation, with the capacitance initialization adapted for the specific type of defibrillator waveform input.
Inventors:
Baura; Gail D. (San Diego, CA)
Assignee:
Kimberly-Clark Worldwide, Inc.
International Classification:
A61N 1/39 (20060101); A61N 039/39 (); A61B 005/00 ()
Expiration Date:
06/26/2018