Simultaneous measurements of shifts of the center of gravity caused by ventilation and cardiac motions towards three body axes

A method is described for the simultaneous measurements of three dimensional shifts of the gravitational center of the body caused by ventilatory and cardiac motions. The measuring system consists fundamentally of three load cells which support an aluminum die-casting platform. Measurement of the shift towards the X axis (front-to-back) was achieved by double integration of the outputs of load cells in order to convert acceleration into a shift of gravity. The records of a volunteer subjects measured with ECG and ventilatory flow showed two cardinal oscillations; one coinciding with the heat rate and the other with the ventilatory frequency. This became clear when recorded through either a low-pass or high-pass filter. Animal who breathed a SF6-O2 mixture into one side of the lungs or those with partial occlusion of a bronchus showed distinct changes in the pattern of the Y axis (right-to-left). These preliminary experiments convinced us that the system can serve as a non-invasive monitoring system of cardiopulmonary functions.