Patent ID: 6625487
Filing Date: 2003-09-23
Classification: A61B,A61N

Abstract:
A multivariate impedance measurement module, for use in an electrotherapy device, said module comprising:a multiple electrode pair control circuit adapted to provide an alternating current, said control circuit connected to at least three electrodes, the electrodes external to the control circuit and adapted to be placed at predetermined relative locations on a patient's body; a controller for controlling said multiple electrode pair control circuit to (a) successively apply the alternating current to all possible pairs of the at least three electrodes, and, during each such application of alternating current, successively measure a voltage across all remaining electrode pairs other than the electrode pair to which the current is being applied; and (b) short each combination of two of the at least three electrodes and apply the alternating current and measure a voltage across each combination of shorted electrodes and the remaining non-shorted electrode, wherein said controller further comprises a resistive network model of the patient's body, said model defined by voltage/current equations having terms representing an impedance of each current path between the at least three electrodes through the patient, wherein the controller solves the equations for the terms representing the impedance of each current path between the at least three electrodes with information obtained by said controller in (a) and (b).