Ventilation and perfusion of the nonventilated lung in pigs during two-lung ventilation 90 min after a 90-min period of one-lung ventilation. Ventilation has returned completely to its initial two-lung value, but perfusion remains significantly less (*P < 0.01) than its initial two-lung value due to residual hypoxic pulmonary vasoconstriction. (Based on data from reference ⁹⁹.)