Noninvasive radioisotopic assessment of pulmonary vascular protein leak. Experimental studies and potential clinical applications.

Noninvasive, double-radioisotope measurement of pulmonary vascular protein leak is a specific and sensitive method for assessing pulmonary vascular permeability. It is sensitive enough to detect increases in vascular protein leak that are too small to produce detectable increases in gravimetric lung water. A simple method for calculating protein leak index reliably reflects expected changes in pulmonary vascular permeability in a broad range of lung injury conditions. This method of measurement may have significant experimental and clinical applications in the study of lung-injury-induced edema, and especially in the evaluation of levels of injury associated with increased permeability but not significant edema. In particular, this method may help to distinguish between increased-permeability edema, such as that which occurs in the adult respiratory distress syndrome, and other types of pulmonary edema in humans.