Venous reservoir ($d{V}_v=C_{v}d{p}_v$)

A lumped venous reservoir stores blood at a pressure determined by its volume and vascular compliance. If its inflow and outflow are $Q_{\mathrm{in}}$, $Q_{\mathrm{out}}$, the constant-compliance approximation gives $C_v{\dot{p}}_v=Q_{\mathrm{in}}-Q_{\mathrm{out}}$. It forms the filling side of a three-compartment ventricular circulation model.