A Guyton-based hypothesis for venous congestion

Figures

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  Figure 1.. The Geometrical Model. This figure shows the detailed equations that predict blood flow, PRA and the right atrial distending venous pressure behind VExUS (PRA minus PPC, see text). In the text, to simplify the discussion, Equations 2 and 3 assume that the pericardial pressure (PPC) is zero; expanded equations show the relationship with VExUS when PPC is included. The pink bars on the x-axis represent the VExUS distending pressure or transmural PRA for each state. The intersection of cardiac function (red) and venous return curve (blue) forms the operating point (OP) which defines the PRA and total blood flow (Q). The GM suggests that the circulation can exist is one of three states that are not mutually exclusive. A.) cardiac limited (or FUR); B.) unlimited (FR); C.) venous limited or venous Starling resistor physiology. PMSF is mean systemic filling pressure and for discussion purposes considered the same as PMSA.

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  Figure 2.. The Geometrical Model and the three types of venous congestion. A.) Shows the approximation of VExUS distending pressure as the pink bar as the base of the cardiac triangle (hypotenuse is 1/RCARDIAC). The pink bar on the x-axis represents PRA minus PPC or the transmural PRA. The intersection of cardiac function (red) and venous return curve (blue) forms the operating point 1 (OP1) which defines the PRA and total blood flow (Q) B.) The difference between increased transmural PRA (i.) versus increased absolute PRA (ii.). The increased transmural pressure (pink bar, x-axis) is from impaired cardiac function (i.e., increased RCARDIAC) while the decreased transmural (green bar, x-axis) but increased absolute PRA (ii.) is caused by elevated PPC. Both i. and ii. have the same operating point 2 (OP2) compared to baseline (OP1). RCARDIAC plateau is not shown for figure clarity C.) Shows the effect of increased PCRIT-1 (e.g., from tumor burden) at operating point 1 (OP1); the initial VExUS is illustrated as the green bar on the x-axis. Reduction of tumor burden decreases PCRIT, increases Q and PRA (OP2) with diminished organ congestion and an increase in VExUS illustrated as the pink bar…