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【課題】心機能の変化による肺インピーダンスの振幅の変化を顕著に捉えることができる。【解決手段】胸壁に植え込まれるカン電極4と、冠静脈に配置される一対の電極5,6と、該一対の電極の一方6とカン電極4との間に定電流を供給する定電流供給部と、一対の電極の他方5とカン電極4との間の電圧を測定する電圧測定部と、定電流供給部によって供給された定電流と電圧測定部によって測定された電圧とを用いてインピーダンスを算出するインピーダンス算出部とを備え、一対の電極5,6は、これら両方の電極が冠静脈内に収容可能な長さ寸法を有するとともに、少なくとも1つは、肺への血流が通常の状態と低下している状態とにおけるインピーダンスの振幅のばらつきの範囲が互いに重ならないような長さ寸法を有する生体インピーダンス測定装置1を提供する。【選択図】図1
