肺シンチグラフィーによるインピーダンス脈波の評価

抄録

Distribution of transthoracic electrical impedance pulse in pulmonary diseases was evaluated by perfusion studies using ^99mTc-macro aggregated albumin (MAA) on 27 subjects.
Impedance was measured at six points in the upper, middle and lower regions of the left and right thorax by a tetrapolar electrode configuration system using a 50kHz current. Pulse height (ΔZ) and the time differential dZ/dt were measured and compared with radioactivity following intravenous administration of ^99mTc-MAA.
In the right and left lung the ratio of radioactivity (Y) to impedance pulse (X) was Y=1.16X, with a correlation coefficient of 0.963.
The shift of pulmonary blood flow before and after bronchography was investigated, and it was found out that after bronchography the amplitude of the impedance pulse decreased and showed the same tendency as the decrease of radioactivity in the lung in which bronchography was performed. Ventilatory volume, calculated from transthoracic electrical impedance variation, decreased in the lung in which bronchography was performed and displayed a strong correlation with changes in the distribution of ^99mTc-MAA. From these results it may be thought that impedance pulses obtained at the thoracic wall may reflect changes in the pulmonary blood flow. Perfusion lung scintigraphy by ^99mTc-MAA is useful in geographically assessing pulmonary blood flow while the impedance method is a useful extra-corporal method for short-term repeated examinations or long term monitoring of pulmonary hemodynamics.