Figure 1.

Stepwise increases in RAP lead to declining venous return and cardiac output. At standstill, MSFP can be measured. The Starling curve (cardiac function) and the venous return curve (vascular function) cross each other in equilibrium. The RAP in this equilibrium point reflects the backpressure to venous return for the VR curve and the preload pressure for the Starling curve. The arrow indicates VRdP. VR, venous return; CO, cardiac output; RAP, right atrial pressure; MSFP, mean systemic filling pressure; VRdP, venous return driving pressure.