Effect of pulmonary venous pressure on steady-stage collateral resistance

Steady-state collateral resistance (Rcoll), residual volume (RV), and lung pressure-volume (PV) relations were determined in an isolated perfused dog lung as pulmonary venous pressure (Ppv) was increased. Increased Ppv had no effect on the lung PV curve except for a significant increase in RV when Ppv equaled or exceeded 20 Torr. When compared to the value at Ppv = 5 Torr, significant decreases in Rcoll occurred when Ppv was raised to 15 Torr or above at transpulmonary pressure, PL = 0 cmH2O, to 20 Torr or above when PL = 2 cmH2O, and to 25 Torr or above when PL = 4 cmH2O. In most dogs the decrease in Rcoll with increased Ppv could be explained by increased lung volume.