Determining health condition statuses using subcutaneous impedance measurements

A method for controlling operation of processing circuitry of a computing device comprising:

• determining, by using the processing circuitry, based at least in part on one or more subcutaneous tissue impedance signals of interstitial fluid, a plurality of tissue impedance values, the one or more subcutaneous tissue impedance signals of interstitial fluid being measured using only a plurality of electrodes on a housing of an insertable cardiac monitor (ICM) disposed in a subcutaneous layer of a patient, wherein at least two electrodes of the plurality of electrodes are positioned within 5 centimeters (cm) apart on the housing;
• determining, by using the processing circuitry, based at least in part on the plurality of tissue impedance values, one or more fluid index values determining, by using the processing circuitry, an adaptive threshold based on an absolute impedance value of at least one of the one or more subcutaneous tissue impedance signals;
• performing, by using the processing circuitry, a comparison of the one or more fluid index values and the adaptive threshold;
• and
• determining, by using the processing circuitry, a health condition status of the patient based at least in part on the comparison.

A non-transitory computer-readable storage medium having stored thereon instructions that, when executed, cause one or more processors to at least:

• determine, based at least in part on one or more subcutaneous tissue impedance signals of interstitial fluid sensed via only a plurality of electrodes on a housing of an insertable cardiac monitor (ICM), a plurality of tissue impedance values, wherein at least two electrodes of the plurality of electrodes are positioned within 5 centimeters (cm) apart on the housing;
• determine, based at least in part on the plurality of tissue impedance values, one or more fluid index values;
• determine an adaptive threshold based on an absolute impedance value of at least one of the one or more subcutaneous tissue impedance signals;
• perform a comparison of the one or more fluid index values and the adaptive threshold;
• and
• determine a health condition status based at least in part on the comparison.