BACKGROUND The purpose of this study was to evaluate the agreement of cardiac output measurements obtained by electrical velocimetry (CO(EV)) and those that derived from the direct Fick-oxygen principle (CO(F)) in infants and children with congenital heart defects. METHODS Simultaneous measurements of CO(EV) and CO(F) were compared in 32 paediatric patients, aged 11 days to 17.8 yr, undergoin...

Many mathematical models of human hemodynamics, particularly those which describe pressure and flow pulses throughout the circulatory system, require as specified input a modeling function which describes cardiac output in terms of volume per unit time. To be realistic, this cardiac output function should capture, to the greatest extent possible, all relevant features observed in measured physi...

A new approach to characterize the kinetics of intravascular mixing process is presented. The mixing time, defined as the time required for achieving 95% homogeneity, is calculated by numerical simulations using a circulatory model applied to the intravascular marker indocyanine green (ICG). The results suggest that the mixing time is determined by cardiac output and the relative dispersion of ...

The resting output of the normal heart has been investigated by many workers (Krogh and Lindhard, 1912; Christiansen et al., 1914; Stewart, 1921; Grollman, 1928; Hamilton et al., 1932; Nylin, 1933; Berseus, 1943; McMichael and Sharpey-Shafer, 1944; Cournand et al., 1945; Stead et al., 1945; Werko, 1947; Chapman et al., 1950; Doyle, et al., 1953; Donald et al., 1955; Goodyer et al., 1960; Reeves...

Experiments were performed on the anesthetized dog to determine the accuracy of the widely used Fick procedure. Cardiac output values, recorded by an optical rotameter, served as a reliable standard for comparison. Under the conditions of these experiments, comparisons showed excellent agreement. The average variation between the two series of the measurements was ±5 per cent. Twelve of thirtee...

• Since the early studies by Hamilton, Werko, and Doyle, and their colleagues, a variety of indicator dilution techniques have been developed for measuring the cardiac output in man. The most widely accepted have been those requiring the use of the continuously recording cuvette densitometer." Numerous studies have appeared to demonstrate close correlation of values by the Hamilton and by the s...

An understanding of the determinants of cardiac output is essential to both medical specialists in their dealing with heart disease and hypertension, and to surgical specialists who deal with shock states and the maintenance of adequate circulation during surgical procedures. In this program, I'll introduce you to some fundamental yet often misunderstood concepts about the determinants of cardi...

Indicator dilution studies are used to provide estimates for several physiological parameters such as cardiac output as well as intra- and extravascular volumes. This study introduces a novel technique for the estimation of recirculatory parameters. A mathematical model based on a dispersion-convection partial differential equation (PDE), derived from the fractal geometry of the vascular tree a...