Method and apparatus for detecting change in intrathoracic electrical impedance

摘要

A method and apparatus for detection of changes in impedance a patient that includes generating measured impedances, generating an adaptive baseline trend of the measured impedances corresponding to a first time period, generating a short term trend of the measured impedances corresponding to a second time period less than the first time period, determining changes in relative position of the short term trend and the baseline trend, the determined changes in relative position corresponding to determining intersecting of the baseline trend by the short term trend, determining differences between the baseline trend and calculated period average impedances, and accumulating, in response to determining no intersecting of the baseline trend by the short term trend, the determined differences between the baseline trend and the calculated period average impedances.

主权项

1. A method of detecting impedance changes of a cardiac signal in a medical device, comprising:
sensing a plurality of impedances in response to the cardiac signal; determining short term average impedances in response to a predetermined number of sensed impedances of the plurality of sensed impedances sensed per day; determining a baseline impedance in response to a plurality of the determined short term average impedances; determining a relative position of the determined short term average impedance and the determined baseline impedance; and determining whether there is a predetermined change in impedance in response to the determined relative position.