Fig. 3.

Example of a venous return curve obtained by the heart–lung interactions method. In this example, end-expiratory and end-inspiratory holds were performed. The 4 pairs of values of central venous pressure and cardiac output obtained during these holds were plotted on a graph, with cardiac output on the y-axis and central venous pressure on the x-axis. The regression line of these points could be equated to the venous return curve. The mean systemic filling pressure (Pmsf) was estimated as the pressure corresponding to the x-intercept of the extrapolated regression line. The resistance to venous return (RVr) was estimated as the inverse of the slope of the regression line