A method for analysis of pulmonary arterial and venous occlusion data

Recently, we presented a compartmental model of the pulmonary vascular resistance (R) and compliance (C) distribution with the configuration C₁R₁C₂R₂C₃ (J. Appl. Physiol. 70: 2126-2136, 1991). This model was used to interpret the pressure vs. time data obtained after the sudden occlusion of the arterial inflow (AO), venous outflow (VO), or both inflow and outflow (DO) from an isolated dog lung lobe. In the present study, we present a new approach to the data analysis in terms of this model that is relatively simple to carry out and more robust. The data used to estimate the R's and C's are the steady-state arterial [Pa(0)] and venous [Pv(0)] pressures, the flow rate (Q̇), the area (A₂) encompassed by Pa(t) after AO and the equilibrium pressure (Pd) after DO, and the average slope (m) of the Pa(t) and Pv(t) curves after VO. The following formulas can then be used to calculate the 2 R's and 3 C's: [Pa(0) - Pv(0)]/Q̇ = R₁ + R₂ = RT, R₁C₁ ≃ A₂/[Pa(0) - Pd], R₁ ≃ [Pa(0) - Pd]/Q̇, Q̇/m = C₁ + C₂ + C₃ = CT, and C₂ = CT - (RTC₁/R₂).