Measurement of Body Fluid Retention using Inductive Coupling

A system, comprising:

• a transformer comprising a primary coil and a secondary coil, wherein one of the primary coil and the secondary coil is configured to be positioned inside a body of a patient, and the other of the primary coil and the secondary coil is configured to be positioned externally to the body;
• and
• circuitry, configured to:
• estimate a measure of magnetic-field inductive-coupling between the primary coil and the secondary coil of the transformer;
• and
• assess fluid retention in an organ of the patient based on the estimated measure of the magnetic-field inductive-coupling.

A method, comprising:

• generating and applying a time-varying signal to a magnetic-field transducer coupled externally to a body of a patient, so as to generate a time-varying magnetic field outside the body of the patient, for supplying electrical energy by inductive coupling to an electronic device that is positioned inside the body;
• estimating an intensity of the magnetic field that reaches the electronic device;
• and
• assessing fluid retention in an organ of the patient based on the estimated intensity of the magnetic field.