Limits on the continuous distribution of pulmonary vascular resistance versus compliance from outflow occlusion

Rapid occlusion of the venous outflow from a lung lobe perfused with constant flow causes the arterial and venous pressure to increase with time. Pressure values obtained by linear extrapolation of the nearly linear portions of the resulting arterial and venous pressure versus time curves back to the instant of occlusion provide data which can be used to place limits on the actual unknown distribution of resistance versus compliance. This has been proven deductively for the case of compartmental models having a small number of resistances and compliances. For compartmental models having a large number of resistances and compliances approaching a continuous distribution, an inductive approach was used in which a large number of simulations indicated that the actual continuous distribution is confined by the experimental data to the same limits as those for the small number of resistances and compliances.