Patent ID: 7945318

Claim:
A method for peripheral impedance plethysmography, the method comprising: (a) attaching an electrode to an extremity of a patient, the electrode comprising two outer current electrodes and two inner voltage electrodes; (b) applying an alternating current to the two outer current electrodes; (c) measuring a voltage in each of the two inner voltage electrodes induced by the alternating current; (d) automatically receiving, in a processing device, the voltage measured in step (c) and a value of a distance between the two inner voltage electrodes, wherein the value of the distance is automatically received in the processing device by automatically generating a signal representing the value of the distance and automatically receiving the signal into the processing device; and (e) calculating, in the processing device, a volume change in the extremity in accordance with the voltage measured in step (c) and the value of the distance received in step (d) such that a result of said calculating depends on the value of the distance.