[Tetrapolar modification of integral body impedance plethysmography]

A decrease in the amplifying ratio of inlet high-frequency amplifiers makes it possible to use PPG2-02 apparatus for tetrapolar modification of integral body impedance plethysmography (IBIP) without the currently used accessory device - divider. In 15 subjects impedance was measured using PPG-01 apparatus in the modification of M. I. Tischenko (intended for bipolar IBIP) or PPG2-02 apparatus. A direct close correlation (r = 0.982) has been established between impedance value, as measured by PPG2-02 apparatus and calculated according to linear regression equation, and impedance value, as measured by PPG2-02 apparatus. Mean deviation of the impedance value measured by PPG2-02 apparatus from that measured by PPG-01 apparatus was 2.8% and did not exceed 6%. The impedance value measured may be used for the determination of the cardiac output and extracellular fluid volume according to M. I. Tishchenko's formulas.