PROBLEM TO BE SOLVED: To make it possible to markedly recognize changes of amplitudes of pulmonary impedance caused by changes of the cardiac function.;SOLUTION: A biological impedance measurement instrument 1 comprises: a can electrode 4 to be implanted in the thoracic wall; a pair of electrodes 5, 6 to be disposed in the coronary vein; a constant current supply part for supplying a constant current between one electrode 6 of the pair of electrode and the can electrode 4; a voltage measurement part for measuring the voltage between the other electrode 5 of the pair of electrodes and the can electrode 4; and an impedance calculation part for calculating the impedance, using the constant current supplied by the constant current supply part and the voltage measured by the voltage measurement part. In this configuration, the pair of electrodes 5, 6 have length dimensions to allow the electrodes to be accommodated in the coronary vein, and at least one electrode of the pair of electrodes has such a length dimension that the range of impedance variations in the state of normal blood flow to the lungs does not overlap the range of impedance variations in the state of decreased blood flow to the lungs.;COPYRIGHT: (C)2014,JPO&INPIT
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