METHOD OF DETERMINING THE STROKE VOLUME AND THE CARDIAC OUTPUT OF THE HUMAN HEART

摘要

Method of determining the stroke volume of the human heart from the pulse-typeblood-stream pressure signal derivedfrom the aorta and consisting in each case of a systolic and a diastolicperiod. Said method comprises calculating the flow q(t)from the pressure p(t) and integrating the flow over the systolic period, theaorta being regarded as a transmission line supple-mented with a windkessel compliance and the pressure/volume relationship inthe aorta as an arctangent relationship. The pres-sure represented by the pressure signal - for each stroke prior to thecalculation of the flow - is linearised by means of the arctan-gent relationship, for fixed aorta length, of the aorta pressure crosssection, the values, associated with the final diastolicpressure, of the characteristic impedance of the transmission line andwindkessel compliance being adhered to or is used withoutmodification. The characteristic impedance of the transmission line and thewindkessel compliance are continuously adapted tothe pressure of the windkessel compliance for each stroke concerned.Additionally, to calculate the flow, the flow through the pe-ripheral resistance is added.