Pulmonary single circulation dilution curves of T-1824, sodium, and tritiated water in intact piglets

In order to assess pulmonary endothelial permeability to sodium in the immature lung, 15 multiple indicator dilution curves were done in eight intact piglets. An indicator bolus consisting of T-1824, 22Na, and tritiated water (THO) was delivered into the right atrium and blood was sampled from the aorta. The concentration of sodium, expressed as a fraction of the quantity injected and of the corresponding fractional concentration of T-1824, was averaged for the samples prior to recirculation. The permeability-surface area product calculated from these data is 2.0 X 10(-5) cm sec-1, and is virtually identical with the value reported elsewhere for adult dogs. Extravascular lung water obtained from the triated water and T-1824 curves averaged 64%, whereas that obtained from the 22Na and T-1824 curves averaged 23% of blood-free lung water.