Numerical simulations showed that mixing time is determined by cardiac output and transit time dispersion, with mixing times >3 min leading to overestimation of blood volume.
What are the determinants of circulatory mixing time in a simulation model?
In states of low cardiac output or high transit time dispersion, slow circulatory mixing can lead to significant overestimation of blood volume when using indicator dilution methods.
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 transit time distribution across the systemic circulation, whereby the rate of mixing increases with increasing cardiac output and decreasing transit time dispersion, and vice versa. The estimation of plasma volume from simulated ICG dilution data using the backextrapolation method shows that slow mixing is accompanied by an overestimation of blood volume. This error may be negligible for mixing times of less than approximately 3 min but high in disease states characterized by low cardiac output and/or high transit time dispersion. In view of the role of transit time dispersion as determinant of intravascular mixing, it would be interesting to know more about the effect of disease states on systemic transit time dispersion.
Michael Weiß (Thu,) reported a other. Numerical simulations using a circulatory model was evaluated on Mixing time (time required for achieving 95% homogeneity). Numerical simulations showed that mixing time is determined by cardiac output and transit time dispersion, with mixing times >3 min leading to overestimation of blood volume.