Assessment of pulmonary vascular injury

The assessment of pulmonary injury in experimental and clinical situations remains a challenge. A method of quantifying pulmonary vascular aberrations in animal models and human clinical situations is described. A multiple-indicator dilution technique is employed to assess changes in lung capillary permeability--surface area product, extravascular lung water, and cardiac output. A mixture of 51Cr-RBC, 125I-albumin, tritiated water, and [14C]urea is injected into a central vein. Samples of the subject's blood are collected at timed intervals and counted for beta and gamma activity. Time concentration curves for each isotope are constructed. The capillary permeability--surface area product is calculated from the extraction pattern for [14C]urea. Extravascular lung water is calculated from the extraction pattern of tritiated water and cardiac output is calculated from the inverse of the area under the 51Cr curve. Normal reference curves are constructed for all subject groups. Significant changes occurred in capillary-permeability surface area product and extravascular lung water in various experimental models producing injury, in the patient population manifesting adult respiratory distress syndrome, and in those patients who have received cardiopulmonary transplants. The multiple-indicator dilution technique represents a sensitive tool for evaluating pulmonary vascular changes.