Patent ID: 8473050

Claim:
An ambulatory medical device comprising: an impedance module including inputs configured to receive impedance signals from respective different electrode configurations associated with a subject's thorax; a cardiac stroke module coupled to the impedance module, the cardiac stroke module configured to: extract corresponding cardiac stroke signals from the impedance signals; and extract corresponding cardiac stroke amplitudes from the cardiac stroke signals; a respiration module coupled to the impedance module, the respiration module configured to: extract corresponding respiration signals from the impedance signals; and extract corresponding respiration amplitudes from the respiration signals; and a processor configured to: compute a comparative measurement between each cardiac stroke amplitude and each corresponding respiration amplitude from the same electrode configuration; and select, based on relative values of the comparative measurement associated with each electrode configuration, a particular electrode configuration for use in obtaining at least one of a cardiac stroke signal or a respiration signal for use in a diagnostic or therapeutic algorithm.