A method of evaluating or monitoring the medical state of a human subject on the subject includes the steps of: positioning an antenna side of a self-contained radio apparatus for non-invasive, thoracic radio interrogation of a human subject proximally to the heart of the human subject providing a radio frequency interrogation interference signal from the human subject, the radio frequency interrogation interference signal being low frequency components of reflections of a radio interrogation signal transmitted into the thorax of the subject and determining with the apparatus on the subject at least at least one stroke volume value of the subject from radio frequency interrogation interference signal generated by the apparatus.
