電気的インピーダンス法による胸郭内呼吸・循環情報

第1報: Z₀およびZ脈波に対応する生理学的事象

抄録

To assure eligibility of the electrical impedance plethysmography as a useful, nontraumatic monitor of intrathoracic ventilatory and circulatory events, a series of experimental studies were carried out since 1967.
In this first part of the report, intrapulmonary flux of the electrical current (52kHz, 1.8mA) which was applied directly on the thoracic surface through 2-P or 4-P electrode arrangement, and correlative changes of the relatively non-variable component of the thoracic impedance (Z₀ component) and of the pulsatile impedance variation (pulsatile dz component) superimposed on the Z₀ component to intrathoracic respiratory and circulatory events were analysed during various manipulations of pulmonary blood flow and intrapulmonary gas within the FRC level.
From these experiments, following results were obtained. The current penetrates through the thoracic wall and distributes preferentially within the lung. Volume of the intravascular and extravascular water within the lung and of the air under FRC level affect Z₀ component of the thoracic impedance. The physiological event as the cause of dz component is pulsatile blood volume change within the pulmonary vasculature, not the mechanical movement during these vascular motion as proposed by D. W. Hill.
From these results, it was suggested that the method is capable to detect congestion and edema of the lung in their early stages, uneven distribution of pulmonary perfusion and changes of pulmonary blood flow as though it is qualitative at present. Further investigation will clarify its value as a clinical monitor of these pysiological events.