Distribution of blood flow and ventilation in saline-filled lung

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Abstract
The airways of degassed greyhound lungs were filled with saline and the lung suspended in a saline bath and perfused with blood. The distribution of blood flow was measured by injecting aggregated I131-labeled albumin into the pulmonary artery and scanning the lung from bottom to top when the particles had been trapped by the small vessels. After equilibrating the alveolar saline with more inhaled iodinated albumin and scanning again, blood flow per unit alveolar volume could be calculated. With vascular pressures which have been shown to cause great topographical inequality of blood flow in the gas-filled lung, blood flow was evenly distributed on the average in the saline-filled preparation, presumably because the hydrostatic pressures difference in the blood vessels were balanced by corresponding pressures in the airways. The topographical distribution of a single breath of iodinated albumin in saline was found to be uniform but there was striking stratified inhomogeneity along the airways. This was due to the slow diffusion rate of albumin in saline and similar effects were seen with inhaled radioactive oxygen and carbon dioxide dissolved in saline. The results show that when the mammalian lung breathes saline, diffusion limitations for oxygen and carbon dioxide within the airways may be an important factor. aerosols; hydrostatic pressures; increased acceleration; airways diffusion; topographical differences; gas exchange; pressure-flow relations Submitted on March 18, 1965